Brainstem Question And Answers

Brainstem Question And Answers

Question 1. Write a short note on the transverse section of medulla at level of decussation of the pyramid.
Answer:

The transverse section of medulla at level of decussation of the pyramid

Resemble the transverse section of the spinal cord and pass through inferior half of medulla.

Abbreviation: MLF—Medial longitudinal fasciculus

Decussation Of Pyramid Gray Matter

• Pyramidal fiers separate anterior horn from the central gray matter
• Anterior horn forms the spinal nucleus of the accessory nerve
• Central gray matter is pushed backward
• Nucleus gracilis and cuneatus are continuous with central gray matter
• Central gray matter is continuous with the nucleus of spinal tract of trigeminal nerve.

Decussation Of Pyramid White Matter

• Pyramids anteriorly
• Decussation of pyramidal tracts
• Fasciculus gracilis and cuneatus occupy the posterior column
• Other features of white matter is similar to the spinal cord.

Question 2. Write a short note on the transverse section of the medulla at the level of sensory decussation.
Answer:

The transverse section of the medulla at the level of sensory decussation

The section passes through the middle of the medulla and following features are seen.

Abbreviation: MLF—Medial longitudinal fasciculus

Sensory Decussation Gray Matter

• Nucleus gracilis and cuneatus are larger and separate from central gray matter
• Accessory cuneate nucleus which relays unconscious proprioceptive fiers from upper limbs
• Nucleus of the spinal tract of the trigeminal nerve is separated from the central gray matter
• Lower part of inferior olivary nucleus seen
• Central gray matter contains a hypoglossal nucleus, dorsal nucleus of vagus, and nucleus of tractus solitarius.

Sensory Decussation White Matter

• Nucleus gracilis and cuneatus give rise to internal arcuate fibers which cross to the opposite side and form a band of fibers called medial lemniscus
• Pyramidal tracts anteriorly
• Medial longitudinal bundle posterior to the medial lemniscus
• Spinocerebellar, lateral spinothalamic tracts in anterolateral area.

Question 3. Write a short note on the transverse section of the medulla at the level of olives.
Answer:

The transverse section of the medulla at the level of olives

The section that passes through the floor of fourth ventricle shows the following features.

Olives Gray Matter: Nuclei of cranial nerves

• Hypoglossal nucleus
• Dorsal nucleus of vagus
• Nucleus of tractus solitarius
• Inferior and medial vestibular nuclei.

Abbreviation: MLF—Medial longitudinal fasciculus

• The nucleus ambiguity lie deep to the reticular foramen
• The dorsal and ventral cochlear nuclei lie on the surface of the inferior cerebellar peduncle
• The nucleus of spinal tract of trigeminal nerve
• The inferior olivary nucleus is the largest mass of gray matter and appear like crumpled purse
• The arcuate nucleus lies anteromedial to the pyramidal tract.

Olives White Matter

• Inferior cerebellar peduncle in the posterolateral part
• Olivocerebellar fibers
• Stria medullaris is the floor of the fourth ventricle
• Ascending tracts
• Emerging fiers of 9, 10, 11 nerves.

Question 4. Write a short note on the transverse section of pons at the level of facial colliculus.
Answer:

The transverse section of pons at the level of facial colliculus

The section passes through a lower level of pons and the following features are seen.

Abbreviation: MLF—Medial longitudinal fasciculus

Facial Colliculus Gray Matter

• Abducent nerve nucleus lie beneath facial colliculus
• Motor nerve nucleus of facial nerve lies ventrolateral to abducent nucleus
• Superior salivatory, inferior salivatory and lacrimatory nucleus lie medial to motor nuclei of facial nerve
• The nucleus of tractus solitarius lies lateral to superior salivatory nucleus
• Vestibular nucleus lie beneath vestibular area
• Dorsal and ventral cochlear nuclei lie dorsal and ventral to inferior cerebellar peduncle
• The spinal nucleus of trigeminal nerve lie anteromedial to inferior cerebellar peduncle.

Facial Colliculus White Matter

• Trapezoid body present posterior to basilar part of pons
• Medial lemniscus in the anterior part of tegmentum
• Spinal lemniscus lying lateral to medial lemniscus
• Medial longitudinal bundle occupying paramedian position
• Tectospinal tract lying ventral to median longitudinal bundle
• Spinal tract to trigeminal nerve lying lateral and dorsal to motor nucleus of facial nerve.

Question 5. Write a short note on transverse section through the upper part of pons.
Answer:

Transverse section through the upper part of pons

This section passes through the trigeminal nuclei and the following features are seen.

Abbreviation: MLF—Medial longitudinal fasciculus

Upper Part Of Pons Gray Matter

• The motor nucleus of trigeminal nerve is situated beneath the lateral part of the fourth ventricle
• The sensory nucleus of the trigeminal nerve is present lateral to motor nucleus of facial nerve.

Upper Part Of Pons White Matter

• Consists of ascending tracts as in lower part of pons
• Lateral lemniscus is well-formed
• Spinal lemniscus lie in between medial and lateral reminisce
• Trigeminal lemniscus is seen between medial and spinal reminisce
• Superior cerebellar peduncle lie dorsolateral to fourth ventricle
• The medial longitudinal bundle is seen.

Question 6. Write a short note on transverse section of midbrain at the level of inferior colliculus.
Answer:

Transverse section of midbrain at the level of inferior colliculus

The section of midbrain at the level of inferior colliculus shows the following features.

Inferior Colliculus Gray Matter: The central gray matter contains the following

• Trochlear nerve nucleus in vertical part
• The mesencephalic nucleus of trigeminal nerve in lateral part.
• Nucleus of inferior colliculus, an ovoid mass of gray matter below inferior colliculus
• Substantia nigra.

Inferior Colliculus White Matter

• The decussation of superior cerebellar peduncles in the central part
• Arrangement of reminisce to form curved compact band in ventral part
• Medial longitudinal fasciculus (MLF) lies in the side of medial plane ventral to trochlear nerve nucleus.

Question 7. Write a short note on transverse section of midbrain at the level of the superior colliculus.
Answer:

Transverse section of midbrain at the level of the superior colliculus

The section shows gray and white matters with the following features.

Superior Colliculus Gray Matter: The central gray mater containing

• Oculomotor nucleus in ventral part
• Mesencephalic nucleus as in the lower part of midbrain.
• Nucleus of superior colliculus
• Pretectal nucleus lying deep to the superolateral part of superior colliculus
• Red nucleus presents vertical to third nerve nucleus.

Superior Colliculus White Matter

• Decussation of fibers from superior colliculus forming dorsal tegmental decussation
• Decussation of fibers arising from red nuclei forming ventral tegmental decussation
• MLF lying ventrolateral to oculomotor nerve.

Brainstem Multiple Choice Question And Answers

Question 1. The transverse section of the medulla at the level of olives shows all of the following except:

1. Hypoglossal nucleus
2. Nucleus of tractus solitarius
3. Nucleus cuneatus
4. Nucleus ambiguous

Answer: 3. Nucleus cuneatus

Question 2. All of the following nuclei are found in pons at the level of facial colliculus except:

1. Abducent nucleus
2. Motor nucleus of trigeminal nerve
3. Motor nucleus of the facial nerve
4. Cochlear nuclei

Answer: 2. Motor nucleus of trigeminal nerve