The Brainstem

Question 1

What is the brainstem

Answer 1

Region that connects cerebrum and spinal cord
Conduit for ascending and descending pathways
Made up of midbrain, pons and medulla oblongata

Question 2

What structures are found at the brainstem

What is it connected to and with what structures

Answer 2

12 pairs of cranial nerves that innervate the head and neck
-10 connected to the brainstem

Connected to higher centers via crus cerebri and cerebellum via peduncles
Conduit for ascending and descending pathways

Question 3

Describe the order of structures found in the brainstem superior <=> inferior

Answer 3

Midbrain
Pons (adjacent to cerebrum)
Medulla oblongata

Question 4

Describe the structures you can see laterally on the brainstem and their functions

Answer 4

Midbrain

• Crus cerebri, fibre bundle that connects cerebral cortex with brainstem and spinal cord
• Inferior colliculus
• Trochlear nerve IV

Pons
-Middle cerebellar peduncle, largest fibre bundle out of 3 peduncles that connects cerebellum with brainstem

Medulla oblongata
-Olive, neurones that connect to cerebellum

Question 5

Describe the structures you can see dorsally on the brainstem and their functions

Answer 5

Midbrain

• Superior colliculus, processing visual reflexes
• Inferior colliculus, processing auditory info
• Trochlear nerve IV, only nerve on dorsal side

Pons

• Sup, mid, inf cerebellar peduncles, at level of 4th ventricle
• Floor and lateral recess of 4th ventricle

Medulla oblongata

• Cuneate tubercle and fasciculus, proprioceptive info from upper body and limbs
• Gracile tubercle and fasciculus, proprioceptive info from lower body and limbs

Question 6

Describe the structures you can see ventrally on the brainstem and their functions

Answer 6

Midbrain

• Mamillary bodies, not part of brainstem, part of hypothalamus
• Crus cerebri

Pons
-Middle cerebellar peduncle

Medulla oblongata

• Pyramids, formed from fibres of CST/pyramidal tract
• Olive

Question 7

Describe a transverse section of the medulla

What are the effects of a stroke on motor function

Answer 7

Dorsally
Gracile tubercle more medial to cuneate tubercle

Ventrally
Pyramids either side of decussation of pyramids
-85% of CST fibres cross to the other side
-Strokes on one side of the brain => hemiplegia on contralateral side