Brainstem

Question 1

Features of White Matter seen in the Medulla at the level of Pyramidal decussation.

Answer 1

1. The fasciculus gracilis and fasciculus cuneatus occupy the posterior white column.
2. The ducussation of pyramidal fibres takes place. These are the corticospinal fibres which cross to the opposite lateral white column to form the Lateral Corticospinal Tract.

Question 2

Features of grey matter in the medulla at the level of pyramidal decussation?

Answer 2

1. Central grey matter surrounding central canal.
2. The anterior grey horns separated from the central grey matter by the decussating pyramidal fibres. It contains spinal nucleus of accessory nerve & nucleus of 1st cervical nerve.
3. The nucleus gracilis and cuneatus are continuous with the central grey matter.
4. Laterally, the central grey matter is continuous with the nucleus of Spinal Tract of trigeminal.

Question 3

Grey matter in the midbrain at the level of inferior colliculus?

Answer 3

1. Periaqueductal grey
2. Mesencephalic nucleus of 5th CN
3. Trochlear nerve nucleus
4. Inferior Colliculus which receives fibres from the auditory tract
5. Substantial Nigra

Question 4

White Matter in the midbrain at the level of Inferior colliculus?

Answer 4

In the Tegmentum:

1. The lemnisci- Medial, Trigeminal, Spinal, Lateral
2. Medial longitudinal bundle
3. Tectospinal and Rubrospinal Tract
4. Decussation of Superior cerebellar peduncle

In the Crus cerebri:

1. The parieto- , temporo-, occipito- pontine fibres in Lateral 1/6th
2. Corticospinal and nuclear fibres in middle 4/6th
3. Frontopontine in medial 1/6th

Question 5

Grey matter in the midbrain at the level of Superior Colliculus?

Answer 5

1) Periaqueductal Grey matter
2) it contains mesencephalic nucleus of Trigeminal and the Occulomotor nerve nucleus along with Edinger- Westphal nucleus
3) Pretectal Nucleus
4) Superior Colliculus
5) Red Nucleus

Question 6

White Matter of midbrain at the level of Superior Colliculus?

Answer 6

1) Crus cerebri contains the same fibres
2) Medial, Trigeminal and Spinal Leminisci (Lateral lemniscus terminated in the inferior Colliculus)
3) Two decussations:
• Dorsal Tegmental - Tectospinal and tectobulbar tracts
• Ventral Tegmental -Rubrospinal Tract
4) Medial Longitudinal Bundle