L6 Overview of Brainstem

Question 1

What are the basic functions of the brainstem?

Answer 1

Modulation of arousal & conscious states

Reflexive & unconscious behaviour

Question 2

Where does the brainstem extend to & from?

Answer 2

Rostrally from maxillary bodies and caudally to pyramidal decussation

Question 3

What is the pyramidal decussastion

Answer 3

Where the white matter tracts from the motor cortex cross over. Occurs in the medulla & signals the end of the brain stem

Question 4

Describe the gross anatomy of the midbrain

Answer 4

Dorsal: Has 2 pais of bumps - superior and inferior colliculi
Ventral: has 2 cerebral peduncles - huge white matter tracks which come down from the motor cortex

Question 5

What are the superior & inferior colliculi important for?

Answer 5

Hearing & eye movement control

Question 6

Describe the gross anatomy of the pons

Answer 6

Dorsal: linked with the cerebellum - dorsolaterally linked by 2 cerebellar peduncles. Limited by the 4th ventricle

Question 7

Describe the gross anatomy of the medulla

Answer 7

Dorsal: Caudally has dorsal columns, nuceli gracile & cuneate tubercle - important for somatosensory pathways
ventral: Rostrally it has 2 bulged - inferior olivary nuclei

Question 8

What are the peduncles of the brainstem?

Answer 8

White matter tracts
1 pair of cerebral penduncles on the ventral surface of the midbrain - huge tracts from the motor cortex (forebrain)

3 pairs of cerebellar peduncles on the dorsal surface - to/from the cerebellum

Question 9

Describe the 3 internal regions of the brainstem & what they contain

Answer 9

1. Dorsal region = tectum = superior and inferior colliculi of the midbrain
2. Middle region = pons + medulla = tegmemtum. Contains ALL brainstem cranial nerve nuclei, most of reticular formation elements and major ascending tracts (sensory)
3. Ventral region = basilar pons. Contains the motor structures i.e. cranial nuclei, motor tracts i.e. corticospinal tract