Upper Limb

• Axillary Region Anatomy
• Bones of the Upper Limb
• Brachialis Anatomy
• Fascia Of The Back
• Muscles of the Anterior Forearm Anatomy

• Muscles of the Pectoral Region
• Nerves Of Upper Limb
• Scapula Anatomy
• Wrist And Hand Anatomy

Upper Limb Introduction

• The forelimbs and hind limbs are developed basically for weight bearing and locomotion in the quadriceps.
• In human beings, evolution brought erect posture and forelimbs are now used for prehension and more skilled works and hind limbs for weight bearing and locomotion, hence called upper limbs and lower limbs respectively.

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• Due to this variation in functions, upper limbs are more mobile at the cost of stability and strength whereas lower limbs are more stable, bulkier, and stronger at the cost of mobility.
• However, on the basis of basic anatomy, the upper limb and lower limb can be compared since they share homologous parts.

Upper Limb Question  And Answers

Question 1. What are the homologous parts shared by upper limb and lower limb?
Answer:

Question 2. What are the parts of upper limb?
Answer:

• Upper limb is divided into:
  • Shoulder region
  • Upper arm (brachium)
  • Fore arm (antebrachium)
  • Hand (manus)

Pectoral Region Introduction

• Pectoral region lies on the front of the chest.
• It consists of structures that connect the upper limb to the anterolateral chest wall.

Pectoral Region Question And Answers

Question 1. Briefly mention the superficial fascia of the pectoral region.
Answer:

Superficial Fascia

• It lies under the skin of the pectoral region and is continuous with surrounding superficial fascia. Its contents are:
  • Moderate amount of fat
  • Cutaneous nerves derived from the cervical plexus and intercostal nerves
  • Cutaneous arterial branches from internal thoracic and posterior intercostal arteries
  • Platysma muscle
  • Breast/mammary gland.

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Question 2. Write a short note on platysma muscle.
Answer:

Platysma Muscle:

Question 3. Explain in detail about the breast under the headings—situation and structure, blood supply, nerve supply, and lymphatic drainage.
Answer:

• The breast is a modified sweat gland.
• It is present in both sexes but rudimentary in males whereas well-developed in females after puberty.
• It is an important accessory organ of the female reproductive system and provides nutrition to the newborn in the form of milk.

Situation, Relations, And Extent

• It is situated in the superficial fascia of the pectoral region except for the tail which pierces the deep fascia of the axilla through the ‘foramen of Langer’ and is called the ‘tail of Spence’
• Breast extends:
  • Vertically: From 2nd to 6th rib
  • Horizontally: Lateral border of sternum to midaxillary line.
  • Superficial Relations: Skin and superficial fascia
  • Deep Relations:
    • Retromammary space: Loose areolar tissue separating the breast from the deep pectoral fascia, hence breast is freely movable over the pectoralis major
    • Pectoral fascia
    • 3 muscles over which the base of the gland rests
      • Pectoralis major
      • Serratus anterior
      • External oblique (a part)
    • Structures deeper to them
      • Clavipectoral fascia
      • Pectoralis major

Structure Of Breast

1. The Structure Of Consists Of:
   • Skin
   • Areola
   • Parenchyma
   • Stroma
2. Structure Of Breast Skin
   • It covers the gland and presents the nipple and areola.
   • The nipple is the conical projection situated usually at the
     center of the breast corresponding to the 4th intercostal space.
   • It is pierced by 15–20 lactiferous ducts.
   • It is rich in sensory nerve endings and very sensitive to touch.
3. Structure of Breast Areola
   • It is the circular area of pigmented skin surrounding the base of the nipple.
   • It is rich in sebaceous glands, especially in the outer margin, which produces oily secretion preventing nipple and areola from drying and crusting.
   • In pregnancy, the areola becomes darker and enlarged.
   • Montgomery’s tubercles are the enlarged sebaceous glands around the nipple in pregnancy.
4. Structure of Breast Parenchyma
   • It is the glandular part of the mammary gland which secretes milk.
   • It consists of 15–20 lobes arranged in a radial fashion around the nipple and opens into it through lactiferous ducts.
   • Each lobe consists of lobules which are filled with clusters of acini-secreting milk.
   • Lactiferous sinuses are dilated part of the lactiferous duct that helps to secrete milk.
5. Structure of Breast Stroma
   • It is the supporting framework of the mammary gland.
   • It is made up of fibrofatty tissue.
   • The fibrofatty tissue is modified to form suspensory ligaments of cooper and suspends breast tissue to the skin and pectoral fascia.

Breast Blood Supply The breast is highly vascular. It is supplied by:

1. Branches of lateral thoracic artery;
2. Branches of internal thoracic artery;
3. Branches of acromiothoracic and superior thoracic arteries
4. Branches of 2nd, 3rd and 4th posterior intercostal arteries

• Arterial Supply
  • Internal thoracic artery through its perforating branches
  • Axillary artery through:
    • Lateral thoracic
    • Superior thoracic
    • Acromiothoracic arteries
  • Posterior intercostal arteries through lateral branches.
• Venous Drainage
  • Axillary vein
  • Internal thoracic vein
  • Posterior intercostal vein.
• Nerve Supply
  • Cutaneous supply by 4th, 5th, and 6th intercostal nerves.
• Lymphatic Drainage
  • Lymphatic drainage of the breast is of great importance as they are the common channels through which metastasis of the breast cancer cells occurs to the opposite breast and other organs.
  • The lymph nodes draining the breast are:

1. Axillary Lymph Node:

• They drain about 75% of the lymph from the breast.
• Among them, lymphatics end mainly in the anterior/pectoral group.
• Lymph from the anterior and posterior groups passes to central and lateral groups and through them to the apical group.
• Eventually, lymph reaches the supraclavicular lymph nodes.

2. Internal Mammary Nodes are arranged along the internal thoracic vessels.

• They drain about 20% of the lymph from the breast.
• They drain from both the inner and outer half of the breast.

3. Supraclavicular Nodes.

4. Cephalic/deltopectoral Lymph Nodes.

5. Posterior Intercostal Nodes.

6. Subdiaphragmatic Lymph Nodes.

7. Subperitoneal Lymph Plexus.

• Lymphatic Vessels draining the breast are:
  • Superficial lymphatics drain the skin over the breast except for the nipple and areola to the surrounding lymph nodes (axillary, internal mammary, posterior intercostal nodes) radially.
  • It is important to note that superficial lymphatics of the breast on one side communicate with those of the opposite side. So unilateral breast malignancies become bilateral through metastasis.
  • Deep lymphatics drain the parenchyma of the breast along with the nipple and areola.
  • The subareolar plexus of sappy is a plexus of lymphatics present deep in the areola. They drain into anterior axillary lymph nodes.
  • Lymphatics from the deeper part of the breast drain directly into the apical group of axillary lymph nodes or to the internal mammary lymph nodes.
  • Few lymph vessels from the inner part of the breast communicate with the subdiaphragmatic and subperitoneal lymphatic plexus.

Clinical Anatomy

• Knowledge of lymphatic drainage of the breast is very important as lymphadenopathy is an early and important sign for staging, treatment, and prognosis of breast cancer.
• Though lymphatics cancer cells can communicate with the opposite breast and other organs in the body.
• Self-examination of the breast stands as the simplest, yet important, way to find malignancy in the early stage itself. On examination note:
  • Symmetry of breast and nipple
  • Change in the color of skin
  • Retraction of nipple
  • Discharge from nipple
  • Any palpable lump
• Cancer cells from the breast can shed of to the peritoneal cavity and move to the ovary causing ovarian tumors known as Krukenberg’s tumor.
• Tubercle of Montgomery stands as an important medico-legal evidence of pregnancy.
• The suspensory ligament of Cooper degenerates with aging and the breast becomes pendulous as age advances.
• Gynecomastia is the development of breasts in males due to hormonal imbalance and other reasons.

Question 4. Write briefly about clavipectoral fascia. What are the structures passing through it?
Answer:

Clavipectoral Fascia is a fibrous sheet situated deep in the clavicular part of the pectoralis major muscle.

Clavipectoral Fascia Extend

• Vertically: From the clavicle above to the axillary fascia below.
• Medially: Attached to the first rib and costoclavicular ligament and blend with the external intercostal membrane of the upper two intercostal spaces.
• Laterally: Attached to the coracoids process and blends with coracoclavicular ligament.
• The clavipectoral fascia is split into two laminae in the upper part to enclose the subclavius muscle.
• The anterior lamina is attached to the clavicle while the posterior lamina is continuous with the investing layer of deep cervical fascia.
• It is split into two laminae in the lower part to enclose the pectoralis minor muscle.
• After enclosing the muscle, it extends downwards as the suspensory ligament of axilla which helps to pull up the dome of axillary fascia.

Structures Piercing the Clavipectoral Fascia

• Lateral pectoral nerve
• Cephalic vein
• Thracoacromial vessels
• Lymphatics from the breast and pectoral region to the apical group of axillary lymph nodes.

Question 5. Enumerate pectoral muscles.
Answer:

Enumerate Pectoral Muscles They are:

• Pectoralis major
• Pectoralis minor
• Known as the key muscle of the axilla as it divides the axillary artery into:
  • Subclavius
  • Serratus anterior (not strictly a muscle of the pectoral region).

Question 6. Write a short note on the pectoralis major muscle.
Answer:

Pectoralis Major

Pectoralis Major Origin

• Small clavicular head: Medial half of anterior aspect of the clavicle
• Large sternocostal head:
  • The lateral half of the anterior surface of the sternum up to the 6th rib
  • The medial end of 2nd to 6th costal cartilages
  • The aponeurosis of the external oblique muscle of the abdomen

Pectoralis Major Insertion

• Inserted into lateral lip of intertubercular sulcus by a U shaped bilaminar tendon
• Anterior lamina of tendon is formed by clavicular fiers
• Posterior lamina formed by sternocostal fiers
• Two laminas are continuous inferiorly
• Lower sternocostal and abdominal fibers are twisted in a way such that the lowest fibers are inserted highest

Pectoralis Major Nerve Supply

• Lateral pectoral nerve
• Medial pectoral nerve

Pectoralis Major Actions

• Clavicular Head: Flexes arm
• Sternocostal Head: Adducts and medially rotates the arm.

Question 7. Write about the origin, insertion, nerve supply, and actions of the remaining pectoral muscles.
Answer:

Question 8. Write a note on the serratus anterior muscle.
Answer:

Serratus Anterior Origin

• 8 digitations from the upper 8 ribs
• Fascia covering intervening intercostal muscles

Serratus Anterior Insertion: Costal surface of the scapula along its medial border

Serratus Anterior Nerve Supply: Nerve to serratus anterior (from the root of C5, C6, and C7)

Serratus Anterior Actions

• Pulls scapula forwards around the chest wall (along with pectoralis major)
• Keep the medial border of the scapula in firm contact with the chest wall
• Rotates scapula laterally and upwards during overhead abduction of arm

Mnemonic

• Serratus anterior: Innervation
• SALT: Serratus Anterior = Long Thoracic

Mnemonic Clinical Anatomy

• Injury to the long thoracic nerve (nerve of bell) can occur in:
  • Stab wounds
  • During the removal of a breast tumor
  • Sudden pressure on the shoulder from above
  • Carrying a heavy load on the shoulder
• It results in paralysis of the serratus anterior and results in winging of the scapula

Pectoral Region Multiple-Choice Questions

Question 1. On climbing a tree, which of these two muscles at together?

1. Teres major and teres minor
2. Latissimus dorsi and teres major
3. Pectoralis major and latissimus dorsi
4. Teres major and pectoralis major

Answer: 3. Pectoralis major and latissimus dorsi

Question 2. Ligaments of cooper are modifications of:

1. Axillary fascia
2. Pectoral fascia
3. The fatty tissue of the breast
4. The fibrous stroma of breast

Answer: 4. Fibrous stroma of breast

Question 3. Which among these does not pierce clavipectoral fascia?

1. Lateral pectoral nerve
2. Cephalic vein
3. Thracoacromial vessels
4. Subclavian artery

Answer: 4. Subclavian artery

Question 4. Which among these are not an early warning sign of breast cancer?

1. Change in the color of skin
2. Gliding mass under the skin of the breast
3. Retraction of nipple
4. Discharge from nipple

Answer: 2. Gliding mass under the skin of the breast

Question 5. Which among these is not a pure pectoral muscle?

1. Pectoralis major
2. Pectoralis minor
3. Serratus anterior
4. Subclavius

Answer: 3. Serratus anterior

Axilla Question And Answers

Question 1. What is an axilla and what are its boundaries and contents?
Answer:

• The axilla or armpit is a four side pyramidal space located between the upper part of the arm and the chest wall.
• It has an apex, base, anterior, posterior, medial, and lateral walls.

Axilla Apex:

• Axilla is directed upwards and medially towards the root of the neck.
• Axilla is truncated, not pointed.
• The axillary artery and brachial plexus enter the axilla through the apex and the passage is called the cervicoaxillary canal.

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Axilla Base:

• Axilla is directed downwards.
• The axillais formed by skin, superficial fascia, and axillary fascia.

Axilla Anterior wall:

• Axilla is formed by:
  • Pectoralis major in front
  • Clavipectoral fascia enclosing pectoralis minor and subclavius deep to pectoralis major muscle

Axilla Posterior Wall:

• Axilla is formed by:
  • Subscapularis above
  • Latissimus dorsi and teres major below

Axilla Medial wall:

• Axilla is formed by:
  • 1st to 4th ribs and their intercostal muscles
  • The upper part of serratus anterior muscle

Axilla Lateral wall:

• Axilla is very narrow
• Axilla is formed by:
  • The upper part of the shaft of the humerus
  • Short head of biceps brachia and coracobrachialis

Axilla Contents

• Axillary artery and its branches
• Axillary vein and its tributaries
• Part of brachial plexus below clavicle
• Five groups of axillary lymph nodes and associated lymphatics
• Long thoracic and intercostobrachial nerves
• Axillary fat and areolar tissue

Axilla Multiple Choice Question

Question 1. Which of the following forms the anterior fold of the axilla?

1. Pectoralis major
2. Pectoralis major and pectoralis minor
3. Pectoral muscles and subclavius
4. Clavipectoral fascia

Answer: 1. Pectoralis major

Back Of The Body Question And Answers

Question 1. Briefly mention the skin and fascia of the back.
Answer:

• As the man lies on his back, the skin is thick and strong in the back and is tied to the underlying fascia.
• The superficial fascia of the back is also thick and strong.

Skin And Fascia Of The Back It contains:

• Cutaneous nerves
• Fat
• Cutaneous arteries and veins
  • The deep fascia is dense in texture.

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Question 2. Enumerate and write about the origin, insertion, nerve supply, and actions of the muscles connecting the upper limb with the vertebral column.
Answer:

• The upper limb is connected to the back of the trunk by a number of muscles
• These muscles are called posterior axioappendicular muscles.
• They are:
  • Trapezius
  • Latissimus dorsi
  • Levator scapulae
  • Rhomboideus minor
  • rhomboideus major

Upper Limb With The Vertebral Column Clinical Anatomy

• Paralysis of the trapezius muscle causes drooping of the shoulder which should be differentiated from a collapsed lung as both can be mistaken for each other.
• A small triangular area of auscultation is present in the back near the inferior angle of the scapula.
• It is bounded by:
  • Superior horizontal border of latissimus dorsi
  • The inferior border of the trapezius
  • The floor is formed by the 6th, and 7th intercostal spaces, seventh rib, and rhomboideus major
• This area is not covered by big muscles. So the underlying upper part of the lower lobe can be auscultated through this area.
• Due to the peculiar feature of latissimus muscle, it can be conditioned and used as an autotransplant to repair a surgically removed portion of the heart.

Back Of The Body Multiple Choice Questions

Question 1. Which of the following can extend, adduct, and medially rotate the arm?

1. Teres minor
2. Subscapularis
3. Latissimus dorsi
4. Deltoid

Answer: 3. Latissimus dorsi

Question 2. All among the listed are actions of trapezius except:

1. Elevation of the scapula
2. Retraction of the scapula
3. Depress the scapula
4. None of them

Answer: 4. None of them

Question 3. All among the listed are actions of latissimus dorsi except:

1. Adduction
2. Extension and medial rotation of arm
3. Helps to climb
4. None among them

Answer: 4. None among them

Question 4. Paralysis of which muscle causes drooping of the shoulder?

1. rhomboideus major
2. Rhomboideus minor
3. Trapezius
4. Serratus anterior

Answer: 3. Trapezius

Question 5. Which muscle can be used as an autotransplant?

1. Rhomboideus minor
2. Trapezius
3. Serratus anterior
4. Latissimus dorsi

Answer: 4. Latissimus dorsi

The scapular region consists of the muscles, intermuscular spaces, nerves, vessels, and anastomosis around the scapula.

Scapular Region Question And Answers

Question 1. Enumerate the muscles around the scapula.
Answer:

• Scapular are originating from the scapula and inserted into the humerus, hence called scapulohumeral muscles.
• Scapular are also called intrinsic shoulder muscles.
• Scapular act on the glenohumeral joint.
• Scapular are:
  • Deltoid
  • Supraspinatus
  • Infraspinatus
  • Teres major
  • Teres minor
  • Subscapularis.

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Question 2. Write a note on deltoid muscle.
Answer:

Deltoid Muscle

• The Deltoid Muscle is a thick, powerful, and curved triangular muscle covering the shoulder joint contributing to its rounded contour.
• The Deltoid Muscle resembles the inverted Greek letter delta, hence the name
• Structurally it is divided into 3 parts:
  • Clavicular part (unipennate)
  • Acromion part (multipennate)
  • Spinous part (unipennate)

Deltoid Muscle Origin

• Clavicular Part (Unipennate): Anterior part of lateral 1/3rd of clavicle
• Acromion Part (Multipennate): Lateral border of acromion
• Spinous part (Unipennate): Lower lip spine of the scapula

Deltoid Muscle Insertion

• Deltoid tuberosity of humerus
• Nerve Supply
• Accessory nerve

Deltoid Muscle Actions

• Anterior Fibers: Flexion and medial rotation
• Middle Fibers: Abduction of the arm
• Posterior Fibers: Extension and medial rotation of the arm

Deltoid Muscle Clinical Anatomy

• Intramuscular injections are given commonly in the lower half of the muscle to avoid injury to the axillary nerve which winds around the neck of the humerus under the muscle.
• In the shoulder region, injury to the supraspinatus tendon is common and the patient feels difficulty in the initiation of abduction of the shoulder joint.
• The tendon of supraspinatus may undergo degeneration and subsequent calcification as advances and results in rupture of the tendon.

Question 3. Write about the origin, insertion, nerve supply, and actions of the muscles around the scapula.
Answer:

Question 4. What is the rotator cuff or musculocutaneous cuff of the shoulder joint? Write about its formation and functions.
Answer:

• It is a fibrous sheath formed by the flattened tendons of four scapulohumeral muscles.
• They are:
  • Supraspinatus fusing superiorly
  • Infraspinatus fusing posteriorly
  • Tere minor fusing posteriorly
  • Subscapularis fusing anteriorly
• It is blended with the capsule of the shoulder joint.

Rotator Cuff Or Musculocutaneous Cuff Functions

• It gives strength to the shoulder joint.
• It grasps and holds the relatively larger head of the humerus
• against smaller and shallower glenoid cavities.

Rotator Cuff Or Musculocutaneous Cuff Clinical Anatomy

• The cuff is deficient inferiorly through which inferior dislocation of the humerus from the joint can take place more easily.

Mnemonic Rotator cuff muscles

• The SITS muscles:
  • Clockwise from top:
• Supraspinatus
• Infraspinatus
• Teres minor
• Subscapularis
• A pro baseball pitcher has injured his rotator cuff muscles.
• As a result, he SITS out for the rest of the game and then gets sent to the minor leagues.

Question 5. Write a short note on the subacromial bursa.
Answer:

• Subacromial Bursa is the largest bursa of the body.
• The Subacromial Bursa is situated below the coracoacromial arch and the deltoid muscle.
• Under the bursa, there are:
  • Tendon of supraspinatus
  • Greater trochanter of the humerus.

Subacromial Bursa Functions

• Subacromial Bursa protects supraspinatus tendons against friction with the acromion process.
• Subacromial Bursa facilitates the movements of the greater tubercle of the humerus under the acromion during overhead abduction.

Subacromial bursa Clinical Anatomy

• Subacromial bursitis commonly appears after inflammation of the supraspinatus tendon. It causes pain when pressure is applied just below the acromion.

Question 6. List the intermuscular spaces with their boundaries and contents.
Answer:

• Quadrangular Spaces are two triangular and one quadrangular spaces formed by the muscles in the scapular region.
• Quadrangular Spaces are seen clearly from behind after reflecting the posterior part of the deltoid.
• They are:

Quadrangular Space Boundaries:

• Superior:
  • Teres minor posteriorly
  • Subscapularis anteriorly
  • The capsule of the shoulder joint between the above two muscles
• Inferior: Teres major
• Medial: Long head of triceps
• Lateral: Surgical neck of the humerus.

Structures Passing Through Quadrangular Space:

• Axillary nerve
• Posterior circumflex humeral artery and vein.

Upper Triangular Space Boundaries

• Superior: Teres minor
• Lateral: Long head of triceps
• Inferior: Teres major

Structures Passing Through Upper Triangular Space:

• Circumflx scapular artery.

Lower Triangular Space Boundaries:

• Medial: Long head of triceps
• Lateral: Shaft of the humerus
• Superior: Teres major.

Structures PassingThrough Lower Triangular Space:

• Radial nerve
• Profunda brachii artery and vein.

Scapular Region

Question 1. The following part of the scapula forms the lateral most palpable landmark on the shoulder:

1. Superior angle
2. Glenoid cavity
3. Coracoid process
4. Acromion

Answer: 4. Acromion

Question 2. Subacromial bursa separates coracoacromial arch from the tendon of:

1. Subscapularis
2. Teres minor
3. Supraspinatus
4. Infraspinatus

Answer: 3. Supraspinatus

Question 3. Which of the following has actions similar to that of teres minor?

1. Supraspinatus
2. Infraspinatus
3. Subscapularis
4. Teres major

Answer: 2. Infraspinatus

Question 4. Which muscle does NOT substantially contribute to the stability of the shoulder joint?

1. Subscapularis
2. Supraspinatus
3. Infraspinatus
4. Teres minor

Answer: 1. Subscapularis

Question 5. Which is NOT a boundary of the quadrangular space?

1. Teres major
2. Teres minor
3. The long head of the triceps
4. Latissimus dorsi

Answer: 4. Latissimus dorsi

Arm Introduction

• Arm extends from the shoulder joint to the elbow joint.
• Humerus is the one and only bone present in the arm.
• Apart from the humerus, the arm consists of neurovascular bundles located medially and muscles arranged in compartments.

Arm Question And Answers

Question 1. Briefly explain the fascial compartments of arm.
Answer:

• The deep fascia covers the arm like a sleeve.
• Lateral and medial intermuscular septa extend inwards from this fascial sleeve and attach to the humerus dividing the arm into anterior and posterior compartments.
• The anterior compartment consists of muscles involved in flexion action, hence called as flexor compartment.
• The posterior compartment consists of the triceps muscle involved in extension action, hence this compartment is called the extensor compartment.
• Two additional septa, the transverse and anteroposterior septa divide the flexor compartment into three.

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Question 2. What are the contents of the anterior compartment of the arm?
Answer:

The Contents Of The Anterior Compartment Of Arm It Consists Of:

• Three muscles
  • Biceps brachii
  • Coracobrachialis
  • Brachialis
• Nerves
  • Musculocutaneous nerve
  • Median nerve
  • Radial nerve Nerves passing through the arm
  • Ulnar nerve
• Brachial artery.

Question 3. Write a note on the biceps brachii.
Answer:

Biceps Brachii Origin: It has two heads of origin:

1. Short head from the coracoid process along with coracobrachialis.
2. Long head from the supraglenoid tubercle of the scapula and glenoid labrum.

Biceps Brachii Insertion

• The main tendon to a posterior rough part of the radial tuberosity
• Bicipital aponeurosis to the skin

Biceps Brachii Nerve Supply

• Musculocutaneous nerve

Biceps Brachii Actions

• Flexion of the elbow
• Powerful supinator when the forearm is flexed
• All screwing actions
• Short head flexes the arm
• The long head prevents the upward displacement of the head of the humerus

Biceps Brachii Clinical Anatomy

The biceps reflex is routinely tested in CNS examination to assess the integrity of the musculocutaneous nerve and C5, and C6 spinal segments.

Question 4. Write about the origin, insertion, nerve supply, and actions of coracobrachialis and brachialis.
Answer:

Mnemonic

• Elbow: muscles that flex it
• Three Bs Bend the elbow:
  • Brachialis
  • Biceps
  • Brachioradialis.

Question 5. What are the anatomical peculiarities of the insertion of the coracobrachialis muscle?
Answer:

• The brachial artery comes to the anterior aspect from its medial position in the arm.
• The median nerve crosses from the lateral to the medial side in front of the brachial artery.
• Below this level, the circular shaft of the humerus becomes triangular.
• The basilic vein pierces the deep fascia.
• The nutrient artery enters the humerus.
• The medial cutaneous nerve of the arm and forearm pierces the deep fascia.
• The radial nerve pierces the deep lateral intermuscular septum and goes from the posterior compartment to the anterior compartment.
• The ulnar nerve pierces the medial intermuscular septum and goes to the posterior compartment.

Question 6. Write a note on the cubital fossa mentioning its boundaries and contents.
Answer:

• Cubital Fossa is a triangular hollow present in front of the elbow.
• Cubital Fossa is homologous with the popliteal fossa in the lower limb.

Cubital Fossa Boundaries

• The Lateral Medial border of the brachioradialis muscle
• Medial Lateral border of pronator teres muscle
• Base Directed upwards, represented by an imaginary line joining the front of the lateral and medial epicondyles of the humerus
• Apex Directed downwards, meeting point of lateral and medial border
• Roof From superficial to Deep:
  • Skin
  • Superficial fascia containing median cubital vein, medial and lateral cutaneous nerves of the forearm
  • Deep fascia with bicipital aponeurosis

Cubital Fossa Content: From the medial to the lateral side are:

• Median nerve
• Brachial artery
• Tendon of biceps brachii.

Cubital Fossa Clinical Anatomy

• A medial cubital vein in the cubital fossa is the vein of choice for intravenous injection.
• When blood pressure is recorded, the BP cuff is wired around the arm to exert external pressure over the brachial artery.
• Supracondylar fracture of the humerus can lead to injury to the brachial artery and median nerve. In such cases, knowledge of the cubital fossa is essential to reduce the fracture.

Question 7. What are the contents of the posterior compartment of the arm?
Answer:

The Contents Of The Posterior Compartment Of The Arm Its Contents Are:

• 1 muscle: Triceps brachii
• 1 nerve: Radial nerve
• 1 artery: Profunda brachii artery.

Question 8. Write a note on the triceps brachii muscle.
Answer:

Triceps Brachii Muscle Origin It has three heads:

• Long head from the infra glenoid tubercle of the scapula
• The lateral head from the oblique ridge present on the upper part of the posterior surface of the humerus
• Medial head from the large triangular area on the posterior surface of the humerus below the radial groove and the medial and lateral intermuscular septa

Triceps Brachii Muscle Insertion

• The posterior part of the superior surface of the olecranon process

Triceps Brachii Muscle Nerve Supply

• Radial nerve

Triceps Brachii Muscle Actions

• Powerful extensor of the elbow

Triceps Brachii Muscle Clinical Anatomy

If the radial nerve is injured in the radial groove, an extension of the elbow and triceps reflex is not lost because the triceps muscle is innervated by the radial nerve in the axilla.

Question 9. Cross-section at the level of the middle of the arm.
Answer:

Arm Multiple Choice Questions

Question 1. Which is the nerve of the anterior compartment of the arm?

1. Axillary nerve
2. Radial nerve
3. Ulnar nerve
4. Musculocutaneous nerve

Answer: 4. Musculocutaneous nerve

Question 2. Which muscle does not belong to the anterior compartment of the arm?

1. Brachialis
2. Brachioradialis
3. Biceps brachii
4. Coracobrachialis

Answer: 2. Brachioradialis

Question 3. Which among these are considered as powerful supinator?

1. Biceps brachii
2. Triceps brachii
3. Coracobrachialis
4. Deltoid muscle

Answer: 1. Biceps brachii

Question 4. Where is the triceps brachii inserted?

1. Medial epicondyle of humerus
2. Lateral epicondyle of humerus
3. Olecranon process
4. Radial tuberosity

Answer: 3. Olecranon process

Question 5. The bicipital aponeurosis is inserted into where?

1. Radial tuberosity
2. Skin
3. Ulnar tuberosity
4. Medial lateral epicondyle of humerus

Answer: 2. Skin

Antebrachium Or Forearm Question And Answers Introduction

The forearm extends from the elbow joint to the wrist joint.

The forearm has two bones, a radius, and an ulna with their interosseous membrane.

Muscles, arteries, veins, and nerves are present in both the front and back of the forearm.

Antebrachium Or Forearm Question And Answers

Question 1. Briefly explain the fascial compartments of the forearm.
Answer:

• The deep fascia of the forearm covers it like a sleeve.
• Intermuscular septa extend from this fascial sleeve and a few of them are attached to the bones dividing the forearm into anterior and posterior compartments.
• Each compartment has its own muscles, nerves, and blood supply.
• The anterior compartment muscles are involved in flexion movement hence, this compartment is called the flexor compartment.
• Posterior compartment muscles are involved in extension movement hence, the compartment is called the extensor compartment.
• Near the wrist, deep fascia thickens in both the flexor and extensor compartments and is called flexor and extensor retinaculum respectively.

Read And Learn More: Upper Limb

Question 2. List the contents of the front forearm.
Answer:

Contents Of Front Forearm

• 8 Muscles Arranged As:
  • 5 superficial muscles
  • 3 deep muscles.
• 2 Arteries
  • Radial artery
  • Ulnar artery.
• 3 Nerves
  • Medial nerve
  • Radial nerve
  • Ulnar nerve.

Question 3. How are the muscles of the anterior compartment of the arm arranged? Enumerate them separately and write the origin, insertion, nerve supply, and actions of them.
Answer:

The anterior compartment of the arm has 8 muscles arranged in superficial and deep layers.

5 Superficial Muscles

• Pronator teres
• Flexor carpi radialis
• Palmaris longus
• Flexor digitorum superfiialis
• Flexor carpi ulnaris.

All the superficial muscles take common origin from the front of the medial epicondyle of the humerus. This is called common flexor origin.

Mnemonic

• Elbow: Which side has a common flexor origin?
• FM (as in FM Radio): Flexor Medial, so common flexor origin is on the medial side.

Three Deep Muscles

1. Flexor digitorum profundus
2. Flexor pollicis longus
3. Flexor carpi ulnaris.

• Flexor digitorum profundus is a hybrid muscle supplied by both the ulnar nerve and anterior interosseous nerve (branch of median nerve).
• It is the most powerful and bulky muscle of the forearm contributing to the larger portion of the gripping power of hand.

Question 4. What are the contents of the back of the forearm?
Answer:

This compartment is also known as the extensor compartment as the muscles of this compartment extend the wrist joint.

Contents Of Back Of The Forearm

• Muscles: 12 muscles arranged as 7 superficial and 5 deep muscles
• Nerves: Posterior interosseous nerve
• Artery: Posterior and anterior interosseous arteries.

Question 5. How are the muscles of the posterior compartment of the arm arranged? Enumerate them separately and write the origin, insertion, nerve supply, and actions of them.
Answer:

The posterior compartment of the arm has 12 muscles arranged in superficial and deep layers.

Seven Superficial Muscles

• From lateral to medial.
• They are:
  • Brachioradialis
  • Extensor carpi radialis longus
  • Extensor carpi radialis brevis
  • Extensor digitorum
  • Extensor digit minimi
  • Extensor carpi ulnaris
  • Anconeus
• All seven muscles cross the elbow joint.
• They have having common extensor origin from the lateral epicondyle of the humerus.
• Dorsal digital expansion is a small triangular aponeurosis related to each tendon of the extensor digitorum.
• It covers the metacarpophalangeal joint and dorsum of the proximal phalanx.
• A number of muscles are inserted into dorsal digital expansion.

Five Deep Muscles

1. From above downwards, they are:
2. Supinator
3. Abductor pollicis longus
4. Extensor pollicis brevis
5. Extensor pollicis longus
6. Extensor indicis

• In contrast to superficial muscles, none of the deep muscles crosses the elbow joint.

Antebrachium Or Forearm Multiple Choice Questions

Question 1. Which of the following pierces the interosseous membrane?

1. Posterior interosseous artery
2. Anterior interosseous artery
3. Common interosseous artery
4. All the above

Answer: 2. Anterior interosseous artery

Question 2. Which one is not a superficial group muscle of the anterior compartment of forearm?

1. Pronator teres
2. Flexor carpi radialis
3. Palmaris longus
4. Pronator quadratus

Answer: 4. Pronator quadratus

Question 3. Which among these is a hybrid muscle?

1. Flexor digitorum profundus
2. Pronator teres
3. Flexor carpi radialis
4. Palmaris longus

Answer: 1. Flexor digitorum profundus

Question 4. The anterior interosseous nerve is a branch of:

1. Musculocutaneous nerve
2. Median nerve
3. Radial nerve
4. Ulnar nerve

Answer: 2. Median nerve

Question 5. Allen’s test is performed to ascertain the proper functioning of:

1. Median nerve
2. Ulnar artery
3. Radial artery
4. Flexor digitorum profundus muscle

Answer: 3. Radial artery

Wrist And Hand Introduction

The hand is man’s physical asset.

A large area in the motor cortex of the brain is represented by the hand indicating the fine as well as complex movements done by hand.

Wrist And Hand Question And Answers

Question 1. What are the peculiarities of skin and superficial fascia of the palmar aspect of the hand? What are the three modifications of deep fascia in this region?
Answer:

Peculiarities Of Skin

• Peculiarities Of Skin is thick and tough.
• Peculiarities Of Skin is rich in sweat and sebaceous glands.
• The palm creases represent the area of the skin attached to the deep fascia of the hand.
• Skin ridges are provided for gripping and those seen on the finger pads are called ‘fingerprints’.

Read And Learn More: Upper Limb

Peculiarities of Superfiial Fascia

• Made of dense fibrous bands bounding skin to the deep fascia.
• Contains subcutaneous fat and Palmaris brevis muscle.

Peculiarities of Deep Fascia

• The deep fascia is modified:
  • In the wrist to form flexor retinaculum.
  • In the palm to form palmar aponeurosis.
  • In the fingers form a fibrous flexor sheath.

Question 2. Write a note on the flexor retinaculum.
Answer:

• Flexor Retinaculum is a strong fibrous band formed by the thickening of deep fascia present in front of the carpus or anatomical wrist.
• Flexor Retinaculum is rectangular in shape and has four borders and two surfaces.

Flexor retinaculum Attachments

• Medial to:
  • Pisiform bone
  • Hook of hamate

1. Palmar cutaneous branch of median nerve;
2. Tendon of palmaris longus;
3. Palmar cutaneous branch of ulnar nerve;
4. Ulnar artery;
5. Ulnar nerve

• Lateral to:
  • Tubercle of scaphoid
  • Crest of trapezium
  • On either side, it gives off a slip.
• Lateral Slip:
• Attached to the medial lip of the groove of the trapezium.
• The slip forms an osseofascial tunnel for the passage of the tendon of the flexor carpi radialis.
• Medial Slip:
  • Attached to the pisiform bone.
  • Ulnar nerve and vessels pass deep to this slip.

Flexor Retinaculum Relations

Flxor Retinaculum Function

• Stabilizes the flexor tendons for smooth action of muscles.

Flexor rRetinaculum Clinical Anatomy

• The median nerve can get compressed in the carpal tunnel called as carpal tunnel syndrome.

Question 3. Write a short note on palmar aponeurosis.
Answer:

It is a well-defined triangular modification of deep fascia in the palm.

Palmar Aponeurosis Boundaries

• Apex:
  • Directed proximally towards the wrist.
  • It blends with the flexor retinaculum.
• Base:
  • Directed distally towards the root of figures.
  • The base is divided into four longitudinal slips, one each for medial 4 figures.
  • The longitudinal slip again splits into two slips which blend with the fibrous sheath of corresponding fingers.
• Medial Border:
  • It is continuous with the deep fascia covering hypothenar muscles.
• Lateral Border:
  • It is continuous with the deep fascia covering the thenar muscles.

Palmar aponeurosis Functions

• Helps to improve the grip of the hand by fixing the skin.
• Stabilizes and protects the underlying structures.

Question 4. Write a short note on the fibrous flexor sheath of the fingers.
Answer:

Deep fascia lying over the anterior aspect of digits thickens to form a fibrous flexor sheath.

Firous Flexor Sheath Of Fingers Extend And Attachments

• Proximally: Continuous with palmar aponeurosis.
• Distally: Attached to the distal phalanx. This forms an osteofascial tunnel through which the flexor tendon passes.

Firous Flexor Sheath Pf fingers Function

• It holds the flexor tendon during the flexion of the fingers.

Question 5. What are the main three synovial sheaths of flexor tendons? Describe each of them.
Answer:

There are mainly 3 synovial sheaths that enclose the tendons of the flexor muscles of the hand.

1. Common flexor synovial sheath/ulnar bursa
   • It encloses the long tendons of both the flexor digitorum superficial and flexor digitorum profundus as they pass through the carpal tunnel.
   • It has two layers the parietal layer lines the walls of the carpal tunnel and the visceral layer lines the tendons.
   • Extend: Upwards up to 5–7 cm into the forearm and downwards into the palm up to the middle of the shaft of the metacarpal bones.
   • The lower medial end is continuous with the digital synovial sheath of the little figure.
2. Radial bursa
   • It encloses the tendons of flxor pollicis longus.
   • Extend
     • Proximally: It coextends with the ulnar bursa
     • Distally: Up to the distal phalanx of the thumb
   • It joins with the digital synovial sheath of the thumb.
3. Digital synovial sheath
   • It encloses the flexor tendons in the fingers and lines the fibrous flexor sheaths.
   • The digital synovial sheath of the little finger is continuous with the ulnar bursa and the digital synovial sheath of the thumb is continuous with the radial bursa.
   • But digital synovial sheaths of index, middle, and ring figures are independent.

Functions Of The Synovial Sheath

• By enclosing the tendons, the synovial sheath reduces friction while the muscle acts.

Clinical Anatomy

• Any penetrating injury caused to the digital synovial sheath can result in tenosynovitis.
• Here, the infection causes distension of the sheath by pus and produces pain.
• If the digital synovial sheath of the thump or little finger is involved, the infection can spread to the radial and ulnar bursa easily due to the continuity.
• It is more dangerous and, if the proximal end of the bursa ruptures, the infection can spread up to the space of the parona. (A fascial space) in forearm.

Question 6. Classify and list out the intrinsic muscles of the hand. Write about their nerve supply and actions.
Answer:

• Intrinsic Muscles are short muscles having origin and insertion within the hand.
• Intrinsic Muscles are responsible for skilled movement and gripping of the hand.
• Intrinsic Muscles can be classified as:

1. Thenar Muscles
   • Abductor pollicis brevis
   • Flexor pollicis brevis
   • Opponents pollicis
2. Hypothenar Muscles
   • Abductor digiti minimi
   • Flexor digiti minimi
   • Opponents digit minimi
3. Adductors Of Thumb
   • Adductor pollicis muscle
4. Muscle Of The Medial Side Of The Palm
   • Palmaris brevis
5. 4 Lubricants
   • Numbered 1–4 from lateral to medial side
6. 4 Dorsal And 4 Palmar Interossei
   • Numbered 1–4 from lateral to medial side

Mnemonics

Interossei Muscles: Actions of dorsal vs Palmar in hand

• PAd And DAb:
  • The Palmar Adduct and the Dorsal Abduct
  • Use your hand to dab with a pad
• Intrinsic Muscles Of The Hand (Palmar Surface) ‘A OF A OF A’:
  • Thenar, lateral to medial:

Question 7. Briefly explain the spaces of the hand.
Answer:

1. Abductor pollicis longus
2. Opponents pollicis
3. Flexor pollicis brevis
4. Adductor pollicis
5. Hypothenar, lateral to medial
6. Opponents digiti minimi
7. Flexor digiti minimi
8. Abductor digiti minimi.

• The fascia and fascial septa of the hand divide the hand into a number of fascial spaces.
• They are potent spaces filled with loose connective tissue but become obvious when they are infected.
• Knowledge of these spaces is of great surgical importance as these spaces can get infected and collected with pus causing distention and pain.
• These spaces are:
  • Palmar Spaces
    • Midpalmar spaces
    • Thenar space
    • Pulp spaces of fingers
  • Dorsal Spaces
    • Dorsal subcutaneous space
    • Dorsal subaponeurotic space
    • The forearm space of the para

Question 8. Write a short note on the mid-palmar space of the hand.
Answer:

Mid-Palmar Space Of the Hand is a triangular-shaped space located under the medial half of the hollow of the palm.

Mid-Palmar Space Of the Hand Boundaries

1. Anterior
   • From superficial to deep:
     • Palmar aponeurosis
     • Superfiial palmar arch
     • Digital nerve and vessels supplying medial 3-and-a-half fingers
     • Ulnar bursa with its tendons
     • 2nd, 3rd, 4th lumbricals
2. Posterior
   • Fascia covering interossei and medial three metacarpals
3. Lateral
   • Intermediate palmar septum
4. Medial
   • Medial palmar septum
5. Proximal
   • Midpalmar space is continuous with forearm space of para
6. Distal
   • Continuous with medial three web spaces through the medial 3 lumbrical canals

Mid-Palmar Space Of the Hand Clinical Anatomy

• The major source of infection in the mid-palmar space is the ulnar bursa.
• When infected, the pus from this space is drained by an incision in the medialmost two web spaces.

Question 9. Write a short note on the thenar space of the hand.
Answer:

Thenar Space Of The Hand is a triangular space located beneath the outer half of the hollow of the palm.

Thenar Space Of The Hand Boundaries

1. Anterior
   • From superficial to deep they are:
     • Palmar aponeurosis
     • Digital nerve and vessels of lateral 1-and-a-half fingers
     • Radial bursa enclosing the tendon of flexor pollicis longus
     • Flexor tendons of index figers
     • First lumbrical
2. Posterior
   • Fascia covering the transverse head of adductor pollicis
3. Lateral
   • Lateral palmar septum
4. Medial
   • Intermediate palmar septum
5. Proximal
   • Only limited space since the anterior and posterior walls fuse in the carpal tunnel
6. Distal
   • Communicates with the first web space through the first lumbrical canal

Thenar Space Of The Hand Clinical Anatomy

• Infections from the radial bursa or synovial sheath of the index finger can reach the thenar space.
• In such cases, pus is drained by an incision in the first web space.

Question 10. Write a short note on the pulp spaces of your fingers.
Answer:

• They are subcutaneous spaces located on the palmar aspect of the tip of the fingers.
• The pulp space is filled with subcutaneous fatty tissue.

Pulp Spaces Of Figures Boundaries

• Superfiial: Skin and superfiial fascia.
• Deeply: Distal 2/3rd of distal phalanx.

Pulp Spaces Of Fingers Clinical Anatomy

• It is the most exposed part of the digit and can get easily infected.
• When infected, the abscess formed in the pulp space is called whitlow.
• The pus from the pulp space is drained by putting a lateral incision.

Question 11. Briefly explain the dorsum of the hand.
Answer:

Dorsum Of Hand Skin

• Loose and thin when hand is relaxed.

Dorsum Of Hand Superficial Fascia

• Contains:
  • Dorsal venous arch
  • Superficial radial nerve
  • Dorsal cutaneous branch of the ulnar nerve.

Dorsum Of Hand Deep Fascia

• Modified to form extensor retinaculum.

Question 12. Write a note on the extensor retinaculum.
Answer:

• The retinaculum is a strong fibrous band formed by the thickening of deep fascia present in the back of the wrist.
• The retinaculum is directed obliquely downwards and medially.
• The retinaculum is 2 cm wide vertically.

Extensor Retinaculum Attachments

• Medially To:
  • Styloid process of ulna
  • Triquetral bone
  • Pisiform bone
• Laterally To:
  • The lower part of the anterior border of the radius.
• Extensor Retinaculum Compartments
  • The retinaculum sends down septa which are attached to the posterior surface of the lower part of the radius.
  • Thus, six osseofascial compartments are formed and each compartment is provided with synovial sheaths.
  • Structures passing through the compartments from lateral to medial side are:

Extensor Retinaculum Functions

• Stabilizes the tendons of extensor muscles for their smooth action.

Question 13. Write a short note on dorsal digital expansion.
Answer:

• They are triangular aponeurosis formed by the expansion of each tendon of the extensor digitorum muscle.
• It covers the dorsum of the metacarpophalangeal joint.
• It fuses anteriorly with a fibrous flexor sheath.
• The tendons of the lumbrical and interossei are inserted into the expansion.
• The expansion narrows as the tendons of the interossei and lumbrical converge towards it on the dorsum of the proximal phalanx.
• From there, it splits into 3 slips.
• The central slip is inserted into the base of the middle phalanx and lateral slips to the base of the terminal phalanx.

Question 14. What is an anatomical snuff box? What are its boundaries and relations?
Answer:

An anatomical Snuff Box is a triangular depression seen on the lateral side of the dorsum of the hand when the thump is hyper-extended.

Anatomical Snuff Box Boundaries

1. Anterolaterally
   • Tendon of abductor pollicis longus
   • Tendon of extensor pollicis brevis
2. Posteromedially
   • Tendon of extensor pollicis longus
3. Floor
   • Scaphoid
   • Trapezium
4. Roof
   • Skin
   • Superficial fascia
5. Content
   • Radial artery

Structures Crossing The Roof Under The Skin:

• Cephalic vein
• Terminal branches of superficial radial nerve

Anatomical Snuff Box Clinical Anatomy

• In scaphoid bone fracture, tenderness in the anatomical snuff box will be present.
• The cephalic vein can be used to give intravenous fluids at this site.
• Radial artery pulsations can be felt in the anatomical snuff box.

Wrist And Hand Multiple Choice Questions

Question 1. Froment’s test is done to check the integrity of the:

1. Second palmar interosseous
2. Second dorsal interosseous
3. Adductor pollicis
4. First lumbrical

Answer: 3. Adductor pollicis

Question 2. Which of the following is not a modification of deep fascia?

1. Extensor retinaculum
2. Palmar aponeurosis
3. Extensor expansion
4. Fibrous flexor sheath

Answer: 3. Fibrous flexor sheath

Question 3. Hammer thumb deformity is due to the rupture of the tendon of

1. Flexor pollicis longus
2. Abductor pollicis longus
3. Extensor pollicis brevis
4. Extensor pollicis longus

Answer: 4. Extensor pollicis longus

Question 4. Adduction of the middle finger is brought about by:

1. Third dorsal interosseous
2. Third lubricants
3. Second and third dorsal interossei
4. Second and third lubricants

Answer: 3. Second and third dorsal interossei

Question 5. What are the four chief bony attachments of the flexor retinaculum?

1. Hamate, pisiform, trapezium, scaphoid
2. Hamate, capitate, trapezoid, scaphoid
3. Lunate, hamate, capitate, scaphoid
4. Lunate, pisiform, trapezoid, hamate
5. Trapezium, trapezoid, capitate, hamate

Answer: 1. Hamate, pisiform, trapezium, scaphoid

Nerves Of Upper Limb Question And Answers

Question 1. Outline the nerve supply of upper limb.
Answer:

• The brachial plexus (C5, C6, C7, C8, T1) provides nerve supply to the upper limb.
• The major nerves originating from the brachial plexus are:
  • Axillary nerve
  • Musculocutaneous nerve
  • Radial nerve
  • Median nerve
  • Ulnar nerve

Question 2. Write in detail about the brachial plexus and make notes on Erb’s and Klumpke’s paralysis.
Answer:

• Brachial plexus is the plexus of nerves formed by the anterior (ventral) rami of the last four cervical and first thoracic spinal nerves. (C5, C6, C7, C8, T1)
• It is divided into five subunits:
  1. Roots
  2. Trunks
  3. Division
  4. Cords
  5. Branches.

Read And Learn More: Upper Limb

Mnemonic: Brachial Plexus Subunits

• ‘Randy Travis Drinks Cold Beer’:
  1. Roots
  2. Trunks
  3. Divisions
  4. Cords
  5. Branches

1. Roots
   • They constitute anterior primary rami of C5 to T1 spinal nerves.
   • They are located in the neck.
2. Trunks
   • Upper trunk is formed by the union of C5 and C6 roots
   • Middle trunk is formed by C7 alone
   • Lower trunk is formed by union of C8 and T1 roots
     • They are also located in the neck.
3. Divisions
   • Each trunk is divided to form anterior and posterior divisions.
   • They are located behind the clavicle
4. Cords
   • Lateral cord is formed by union of the anterior division of upper and middle trunk.
   • Medial cord is a continuation of anterior division of lower trunk.
   • The posterior cord is formed by the union of the posterior division of all trunks.
   • Cords are located in the axilla.
5. Branches of Brachial Plexus
   • From roots
     • Long thoracic nerve/nerve to serratus anterior
     • Dorsal scapular nerve/nerve to rhomboids
   • From trunks
     • Suprascapular nerve
     • Nerve to subclavius
   • From cords
     • From lateral cord
       • Lateral pectoral nerve
       • Lateral root of median nerve
       • Musculocutaneous nerve
     • From medial cord
       • Medial pectoral nerve
       • Medial cutaneous nerve of arm
       • Medial cutaneous nerve of forearm
       • Medial root of median nerve
       • Ulnar nerve

• • • From posterior cord
      • Radial nerve
      • Axillary nerve
      • Thracodorsal nerve/nerve to latissimus dorsi
      • Upper subscapular nerve
      • Lower subscapular nerve

Mnemonic: Brachial plexus: Branches of the posterior cord

STAR

• Subscapular [upper and lower]
• Thoracodorsal
• Axillary
• Radial

Clinical Anatomy: Two types of lesions occurring in brachial plexus are important.

1. Erb’s paralysis:
   • There is a point in the brachial plexus where six nerves meet called Erb’s point. These meeting nerves are:
     • 5th and 6th cervical roots
     • Upper trunk formed by the union of these nerve roots
     • Suprascapular nerve and nerve to subclavius branching from the upper trunk
   • Any accident which causes an increase in angle between the head and shoulder can cause injury to the upper brachial plexus most commonly at Erb’s point.
   • It results in a specific type of paralysis of the upper limb known as Erb’s paralysis
   • For example A fall on the shoulder, birth injury, following anesthesia, etc.
   • The clinical features are given in the table.
2. Klumpke’s paralysis.
   • It is another type of paralysis of the upper limb caused by accidents that increases angle between the trunk and shoulder making injury to lower brachial plexus.
   • For example Sudden upward pulling of the arm, birth injury, etc.

Question 3. Explain in detail about axillary nerve under headings—origin, root value, course, branches, and innervation. Make a note on the injury to the nerve.
Answer:

• It is called axillary because it runs through the upper part of the axilla.
• It is called circumflex because it courses around the surgical neck of humerus.

Axillary Nerve Origin

• It is smaller terminal branch of posterior cord of brachial plexus.

Axillary Root Value

• Ventral rami of C5, C6 segments.

Axillary Nerve Course

• From the posterior cord, it passes backward through the quadrangular intermuscular space.
  • After reaching back, it divides into anterior and posterior divisions below the capsule of the shoulder joint.
  • The posterior division again divides and one part continues as upper lateral cutaneous nerve and the other part goes to supply deltoid and teres minor with a pseudoganglion in it.
  • The anterior division supplies deltoid muscle and skin over its anteroinferior part (regiment badge).

Axillary Nerve Branches and Innervation

• Trunk Of Axillary Nerve
  • Articular branch to the shoulder joint
• Anterior Division
  • Muscular branch to deltoid-cutaneous branch to the skin over deltoid’s anteroinferior part (regimen badge)
• Posterior Division
  • The cutaneous branch continues as the upper cutaneous nerve of the arm.
  • Muscular branch to teres minor and posterior part of the deltoid.

Axillary Nerve Clinical Anatomy

• The axillary nerve can easily get injured in inferior dislocation of the humerus or in injury to the surgical neck of the humerus.
• The presentation will be:
  • Impaired abduction.
  • Loss of contour of the shoulder due to deltoid muscle wasting.
  • Loss of sensation over the lower half of the deltoid (regimen badge).

Question 4. Explain in detail about musculocutaneous nerve under headings—origin, root value, course, branches, and innervation. Make a note on the injury to the nerve.
Answer:

It is the nerve of front of the arm.

Musculocutaneous Nerve Origin

• Lateral cord of brachial plexus in the axilla.

Musculocutaneous Nerve Root Value

• C5, C6, and C7 spinal segments.

Musculocutaneous Nerve Course

• From the lateral cord of the brachial plexus, it runs downwards and laterally pierces coracobrachialis by supplying it.
• From there, it further descends downwards in between the biceps brachii, and brachialis muscles by innervating them.
• It reaches the lateral aspect of the biceps tendon to pierce the deep fascia just above the elbow joint.
• From there, it continues down as the lateral cutaneous nerve of the forearm.

Musculocutaneous Nerve Branches and Innervation

• Muscular branches supplying
  • Biceps brachii
  • Coracobrachialis
  • Brachialis
• Cutaneous branch (lateral cutaneous nerve of the forearm)
  • Supplies skin over the front and lateral aspect of the forearm.
• Articular branch
  • To the elbow joint

Musculocutaneous Nerve Clinical Anatomy

• Injury to the musculocutaneous nerve though rare can cause loss of
  • Flexion of elbow
  • Biceps tendon reflux
  • Loss of sensation over the lateral aspect of the forearm.

Question 5. Explain in detail about radial nerve under headings—origin, root value, course, branches, and innervation. Write a note on injury to the nerve.
Answer:

• It is the largest nerve of the brachial plexus.
• In general, it is the nerve of the dorsum of the arm, forearm, and hand.

Radial Nerve Root Value

• C5–C8, T1 spinal segments.

Radial Nerve Origin

• It is the continuation of the posterior cord of the brachial plexus.

Radial Nerve Course

• From the posterior cord, the radial nerve descends downwards to enter the axilla.
• In the axilla radial nerve has three branches:
• The posterior cutaneous nerve of the arm
• Nerve to the long head of triceps
• Nerve to medial head of triceps
• From the axilla, the radial nerve enters the posterior compartment of the arm through the intermuscular space between the medial and long head of triceps.
• The radial nerve reaches the spiral groove of the humerus and gives 5 branches:
  1. The lower lateral cutaneous nerve of arm
  2. The posterior cutaneous nerve of arm
  3. Nerve to the lateral head of triceps
  4. Nerve to medial head of triceps
  5. Nerve to anconeus.
• At the lower end of the spiral groove, the radial nerve pierces the lateral intermuscular septum to reach in between the brachialis and brachioradialis.
• It descends further down to run between the brachialis and extensor carpi radialis longus and enters the cubital fossa.
• In the anterior compartment of the arm, above the level of the lateral epicondyle, it gives of 3 branches:
  1. Brachialis
  2. Nerve to brachioradialis
  3. Nerve to extensor carpi radialis longus
• It then divides into superficial and deep branches at the level of the lateral condyle of the humerus in the cubital fossa.
• The deep branch or posterior interosseous nerve supplies 2 muscles:
  1. Extensor carpi radialis brevis
  2. Supinator
• The deep branch further descends down to enter the posterior compartment and supplies:
  • All extensors of the forearm
  • Distal radioulnar, wrist, and carpal joints.
• The superficial branch passes down to the hand over the tendons of the anatomical snuff box to terminate as a cutaneous branch.

Radial Nerve Branches And Innervation

Mnemonic: Radial Nerve: Muscles Innervated

• ‘Try A Big Chocolate Chip Sundae, Double Dip Cherries And Peanuts Preferably Included’:
• In order of their innervation, proximal to distal:
  • Triceps
  • Anconeus
  • Brachioradialis
    • Extenstion Carpi radialis longus
    • Extension Carpi radialis brevis
  • Supinator
    • Extension Digitorum
    • Extension Digiti minimi
    • Extension Carpi ulnaris
  • Abductor poll. longus
    • Extension Poll. brevis
    • Extension Poll. longus
    • Extension Indicis
• For the neighboring words that start with the same letter (for example, chocolate and chip), notice that the longer word in the mnemonic.
• Corresponds to the longer of the two muscle names (example: extensor carpi radialis longus and ext. carpi radialis brevis).

Radial Nerve Clinical Anatomy

• Radial nerves can get injured at various sites.

1. Injury to the radial nerve in the axilla can occur due to pressure from the upper end of crutch called as crutch palsy.
2. Injury to radial nerve in radial or spiral groove can occur due to:
   • Midshaft fracture of humerus
   • The pressure was applied on the radial nerve against the humerus by a drunker who is asleep with the medial aspect of his arm resting over the chair (Saturday night palsy).
     • In such situations, the presentation will be:
       • Loss of extension of wrist and fingers (wrist drop).
       • Loss of supination when the arm is extended.
       • Sensory loss is restricted only to a small area over the dorsum of the hand in between first and second metacarpals.
3. Injury to radial nerve at the elbow
   • It is called radial tunnel syndrome.

Question 6. Explain in detail about the ulnar nerve under headings— origin, root value, course, branches, and innervation. Write a note on injury to the nerve.
Answer:

• The Ulnar Nerve runs along the ulnar side of the upper limb hence the name.
• Ulnar Nerve is the nerve of fie movement and is called the musician’s nerve.

Ulnar Nerve Origin

• Medial cord of brachial plexus.

Ulnar Nerve Root Value

• C8 and T1 spinal segments mainly. C7 also contributes.

Ulnar Nerve Course

1. In the axilla: the Ulnar nerve lies medial to the third part of the brachial artery.
2. In the arm:
   • It enters the arm along the medial side of the brachial artery and runs up to the level of the mid-arm.
   • The ulnar nerve pierces the medial intermuscular septum to reach the back of the arm.
   • From there, the ulnar nerve descends down to pass through the cubital tunnel formed by the medial epicondyle and the fibrous band extending from the medial epicondyle to the olecranon process.
   • The ulnar nerve has no branches in the axilla as well as in the arm.
3. In the forearm:
   • In the upper 1/3rd, the ulnar nerve passes between the two heads of flexor carpi ulnaris to reach underneath the muscle and runs vertically down.
   • In the lower 2/3rd, it becomes superficial and runs downwards along with the ulnar artery being on the lateral side.
   • Branches of the ulnar artery in the forearm are:
   • Proximal forearm Muscular branch:
     • Flexor carpi ulnaris
     • Medial half of flxor digitorum profundus
   • Mid forearm
     • Cutaneous branch: Palmar cutaneous branch
   • Distal forearm
     • Cutaneous branch: Dorsal cutaneous branch

Ulnar Nerve In the Hand

• The ulnar nerve enters the hand superficial to the carpal tunnel through the ulnar tunnel and divides into superficial and deep terminal branches.
• The superficial branch gives sensory supply to the palmar aspect of the medial ½ digits and motor supply to palmaris brevis muscle.
• Deep branches give off
  • Articular branches to the wrist
  • Muscular branches to:
    • 2 medial lumbricals
    • 4 palmar interossei
    • 4 dorsal interossei
    • Flexor digiti minimi (hypothenar muscle)
    • Abductor digiti minimi (hypothenar muscle)
    • Opponents digiti minimi (hypothenar muscle)
    • Adductor pollicis (thenar muscle)

Ulnar Nerve Branches and Supply

Ulnar Nerve Clinical Anatomy: Injury to the ulnar nerve can occur in the elbow or wrist.

1. Injury To The Ulnar Nerve At The Elbow
   • Common causes are:
     • Compression of the nerve in between the two heads of flexor carpi ulnaris
     • Fracture and dislocation of medial epicondyle
     • Valgus deformity of the elbow
     • Thickening of the fibrous roof of the cubital tunnel (cubital tunnel syndrome).

• • • Claw hand deformity affecting ring and little fingures where the metacarpophalangeal joints are extended while the interphalangeal joints are fixed (its actually not a complete claw hand, complete claw hand is seen when both ulnar nerve and medial nerve are injured simultaneously resulting in the hyperextended wrist and metacarpophalangeal joints and fixed interphalangeal joints).
    • Flattening of the hypothenar eminence due to atrophy.
    • Adduction and abduction of figers are affcted.
    • Thmp can not be adducted.
    • Loss of sensation over the palmar and dorsal surface of the medial 1/3rd of hand and medial 1-and-a-half
    • fingers
    • Foments sign will be positive when the integrity of the palmar interossei is tested.
    • The ulnar nerve can also get injured in the wrist. Here, the clawing is more pronounced known as the ulnar paradox.

Question 7. Explain in detail about the median nerve under headings—origin, root value, course, branches, and innervation. Write a note on injury to the nerve.
Answer:

• The median nerve is called the median because it runs in the median plane of the forearm.
• It is called the eye of the hand because it gives sensory supply to the pulp of the thumb and index fingers.
• It is also known as the laborers’ nerve.

Median Nerve Origin

• By the union of the medial and lateral cord of the brachial plexus.

Median Nerve Root Value

• C5, C6, C7, C8, T1.

Median Nerve Course

1. In the axilla:
   • The median nerve goes down to enter in the arm from the lateral side of 3rd part of the axillary artery.
2. In the arm:
   • The median nerve lies lateral to the brachial artery.
   • But at the level of the middle of the arm, it crosses the brachial artery and runs medial to enter the cubital fossa.
3. In the cubital fossa:
   • It gives of muscular branches to flexor carpi radialis, flxor digitorum superfiialis and palmaris longus.
   • The median nerve leaves the cubital fossa between two heads of pronator teres and then deep to the fibrous arch of the flexor digitorum superficial.
4. In the forearm:
   • In the forearm, it is adhered to the deep surface of the flexor digitorum superficial and leaves the muscle along its lateral border.
   • It runs deep to the palmaris longus and gives of the palmar cutaneous branch before getting under the carpal tunnel.
5. In the palm:
   • After passing through the carpal tunnel, the median nerve divides into lateral and medial divisions.
   • Lateral division supplies 3 out of 4 thenar muscles, 1st and second lumbricals.
   • Medial division along with the remaining fingers of lateral division provides cutaneous supply to the lateral 3 and half digits and their nail beds including the skin of distal phalanges on their dorsal aspect.

Median Nerve Branches and Innervations

Mnemonic: Median Nerve: Hand Muscles Innervated

‘The LOAF muscles’:

• lumbrical 1 and 2
• Opponents pollicis
• Abductor pollicis brevis
• Flexor pollicis brevis
• Alternatively: LLOAF, with 2 L’s, to recall there is 2 lumbricals.
• To remember that these are the Median nerve muscles, think ‘Meat LOAF’.

Median Nerve Clinical Anatomy

• Injury to the median nerve can occur at various levels and the clinical features vary accordingly.

1. Injury At The Level Of The Elbow
   • It can be due to:
     • Supracondylar fracture of humerus.
     • Entrapment of nerve between the two heads of pronator teres during its course.
     • Tight tourniquet usage during venipunctures.
   • The clinical features are:
     • Loss of pronation as pronator teres is paralyzed.
     • Weak wrist flexion due to paralysis of flexors supplied by the median nerve.
     • The wrist will be adducted due to weakening of the flexor carpi radialis and unopposed action of the flexor carpi ulnaris and medial half of flexor digitorum profundus.

• Benedicts Deformity:
  • Median nerve injury leads to no flexion at interphalangeal joints of the index and middle fingers due to paralysis of the flexor digit running the superficial and lateral half of the flexor digitorum profundus. It results in placing of hand in a position comparable to Benedict’s hand.

• Ape thumb deformity:
  • It is characterized by flttening of thenar eminence with lateral rotation and adduction of thumb due to paralysis of thenar muscles supplied by the median nerve

1. Injury At The Level Of The Forearm

2. Injury At The Carpal Tunnel:

• Median nerve can get compressed in the tightly packed carpal tunnel due to:
  • Myxedema
  • Tenosynovitis of flxor tendons
  • Dislocation of lunate bone following fracture
  • Retention of fluid in pregnancy
  • Osteoarthritis in the wrist joint
• It is presented with:
  • Burning sensation over the area of sensory supply of median nerve in the hand (lateral 3½ digits) more during the night
  • Weakening of thenar muscles
  • Ape thumb deformity, if left untreated
  • Reduced conduction velocity in nerve conduction studies
  • Phalen’s test and Tinel’s test were positive.

Mnemonic: Carpal Tunnel Syndrome Causes

MEDIAN TRAP

• Myxoedema
• Edema premenstrually
• Diabetes
• Idiopathic
• Acromegaly
• Neoplasm
• Trauma
• Rheumatoid arthritis
• Amyloidosis
• Pregnancy

Mnemonic fits nicely since the median nerve is trapped.

Question 8. Write a note on the cutaneous supply of the upper limb.
Answer:

• The upper limb is supplied by C3–T2 spinal segments
• This is via:
  • Supraclavicular nerves (C3 and C4)
  • Nerves from brachial plexus (C5–T1)
  • Intercostobrachial nerve (T2)

1. Pectoral Region
   • Above the 2nd rib by supraclavicular nerves (C3, C4)
   • Below the 2nd rib by intercostal nerves (T2–T6).
2. Axilla
   • Intercostobrachial nerve (T2)
   • Small branches from (T3).
3. Shoulder
   • Upper half of deltoid by supraclavicular nerves (C3, C4)
   • The lower half of the deltoid by the upper lateral cutaneous nerve of the arm.
4. Arm
   • Upper medial part by the intercostobrachial nerve (T2)
   • Lower medial part by the medial cutaneous nerve of the arm (T1, T2)
   • Upper lateral half by upper lateral cutaneous nerve of arm
   • Lower lateral part by lower lateral cutaneous nerve of arm (C5, C6)
   • Posterior aspect of the arm by the posterior cutaneous nerve of the arm (C5).
5. Forearm
   • The medial side of the forearm by the medial cutaneous nerve of the forearm (C8, T1)
   • The lateral side of the forearm by lateral cutaneous nerve of the forearm (C5, C6)
   • Posterior aspect of the forearm by the posterior cutaneous nerve of the forearm (C6, C7, C8).
6. Hand
   • Palmar Surface
     • Lateral 2/3rd of the palm by a palmar cutaneous branch of the median nerve
     • Medial 1/3rd of the palm is supplied by the palmar cutaneous branch of the ulnar nerve.
   • Dorsal surface
     • Lateral 2/3 rd of the dorsum by superficial terminal branch of radial nerve
     • Medial 1/3 rd by dorsal branch/posterior cutaneous branch of the ulnar nerve.
7. Digits
   • Palmar Surface
     • Lateral 3½ digits up to distal half of the middle phalanges by digital branches of median nerve
     • Medial 1½ digits up to distal half of the middle phalanges by palmar digital branch of ulnar nerve
   • Dorsal Surface
     • Lateral 3½ digits up to the proximal half of their middle phalanges by digital branches of radial nerve
     • Lateral 3½ digits up to distal half of the middle phalanges by digital branches of median nerve
     • Medial 1½ digits up to their middle phalanges by digital branches of the ulnar nerve
     • Medial 1½ digits up to the distal half of the middle phalanges by a palmar digital branch of the ulnar nerve.

Question 9. Draw the dermatomes of the upper limb.
Answer:

• The area of the skin supplied by one spinal segment is called a dermatome.
• Dermatomes of the upper limb are given in the picture.

Nerves Of Upper Limb Multiple Choice Questions

Question 1. What is the continuation of ventral rami of 7th spinal cord called?

1. Medial cord
2. Upper trunk
3. Middle trunk
4. Lateral cord

Answer: 3. Middle trunk

Question 2. A patient presents with loss of abduction and weakness of lateral rotation of the arm. This is due to injury to a nerve caused by a fracture of the humerus at:

1. Anatomical neck
2. Midshaft
3. Surgical neck
4. Medial epicondyle

Answer: 3. Surgical neck

Question 3. Which nerve is injured if on trying to make a circle by touching the tip of index finger and thumb, the approximation of palmar spaces of distal phalanx occurs (as in pinching)?

1. Median nerve at wrist
2. Anterior interosseous nerve
3. Recurrent branch of the median nerve
4. Deep branch of ulnar nerve

Answer: 2. Anterior interosseous nerve

Question 4. A sportsman with a severe injury to their right leg had to use crutches for several months. Subsequently, his doctor found that he had restricted abduction of shoulder and extension of the elbow. What is the site of injury to the brachial plexus?

1. Middle trunk
2. Posterior cord
3. Lateral cord
4. Medial cord

Answer: 2. Lateral cord

Question 5. Which dermatome overlies the thumb?

1. T1
2. C8
3. C7
4. C6

Answer: 4. C6

Question 6. The skin overlying the thenar eminence is supplied by:

1. Recurrent branch of the median nerve
2. Palmar cutaneous branch of ulnar nerve
3. Palmar cutaneous branch of the median nerve
4. Lateral proper digital branch of the median nerve

Answer: 3. Palmar cutaneous branch of the median nerve