Brainstem and cranial nerves (9)

Question 1

What is the order of components in the brainstem from top to bottom?

Answer 1

• midbrain
• pons
• medulla

Question 2

How many cerebellar peduncles connect the cerebellum to the brainstem?

Answer 2

6 (3 on each side: superior, middle and inferior)

Question 3

How many cranial nerves have their nuclei in the brainstem?

Answer 3

9/12 pairs (3–>12 except 11)

Question 4

What is the generic internal structure of the brainstem that follows throughout the midbrain, pons and medulla?

Answer 4

• tectum towards back of brainstem (sits behind cerebral aqueduct)
• tegmentum in front of cerebral aqueduct
• base is the anterolateral portion

Question 5

Which cranial nerves emerge at midbrain level?

Answer 5

III (oculomotor) from anterior aspect and IV (trochlear) from posterior aspect

Question 6

Which cranial nerves emerge at pons level?

Answer 6

V (trigeminal), VI (abducens), VII (facial) and VIII (vestibulocochlear)

Question 7

What are the key features of the medulla?

Answer 7

• rostral continuation of the spinal cord
• anterior surface has mamillary bodies, cerebral peduncles and medullary pyramids (contain descending tracts)
• posterior surface has pineal gland, colliculi and dorsal columns
• posterior surface divided into open and closed
• closed medulla has extension of central canal of spinal cord
• -> canal widens to form 4th ventricle in open medulla

Question 8

Which cranial nerves emerge from the medulla?

Answer 8

IX (glossopharyngeal), X (vagus) and XII (hypoglossal)

Question 9

What do these stand for:
GSE
GVE
GSA
GVA
SVE
SSA

Answer 9

general somatic efferent
general visceral efferent
general somatic afferent
general visceral afferent
special visceral efferent
special somatic afferent

Question 10

What are the superior and inferior colliculi?

Answer 10

• part of tectum
• superior colliculi surround the pineal gland and are involved in the visual pathway
• inferior colliculi involved in auditory pathway

Question 11

What is the difference between the open (upper) and closed (lower) medulla?

Answer 11

• closed medulla: 4th ventricle completely enclosed by neural tissue
• open medulla: 4th ventricle has no roof

Question 12

What arterial system supplies the forebrain?

Answer 12

carotid system supplies most of the cerebral hemispheres

Question 13

What arterial system supplies the brainstem?

Answer 13

vertebrobasilar

Question 14

What are the 2 functions of the oculomotor nerve?

Answer 14

• provide motor neurones to skeletal muscle fibres that move the eye (oculomotor nucleus, GSE)
• role in reflexes: pupillary light reflex and accommodation reflex (Edinger Westphal nucleus, GVE)

Question 15

What is the function of the trochlear nerve?

Answer 15

motor to superior oblique in eye (GSE)

Question 16

What nuclei does the trigeminal nerve have?

Answer 16

3 sensory: mesencephalic, chief nucleus, and spinal nucleus (all GSA)
1 motor: motor nucleus (SVE) to muscles of mastication