Organisation of the brainstem and cranial nerves

Question 1

What is the brainstem?

Answer 1

That part of the CNS, exclusive of the cerebellum, that lies between the cerebrum and the spinal cord.

Question 2

What are the major divisions of the brainstem?

Answer 2

Medulla oblongata Pons Midbrain

Question 3

What is the function of the pineal gland?

Answer 3

Secretes melatonin Vital for maintaining circadian rhythms- hormone release, e.g. cortisol. Day-night cycle.

Question 4

Where is the pineal gland?

Answer 4

Dorsal midbrain, midline structure.

Question 5

What is the function of the superior colliculi?

Answer 5

Coordinated movement of neck, head and eyes- e.g. watching tennis.

Question 6

What is the function of the inferior colliculi?

Answer 6

Auditory reflex- turning head in reaction to loud noise.

Question 7

Which cranial nerve emerges from the dorsal midbrain?

Answer 7

Trochlear nerve, CNIV.

Question 8

What is the function of CNIV, the trochlear nerve?

Answer 8

Supplies superior oblique muscle of the eye.

Question 9

What structure forms the roof of the 4th ventricle?

Answer 9

Cerebellum

Question 10

Which sensory modalities are carried in the dorsal columns?

Answer 10

Touch and proprioception

Question 11

What are the 2 dorsal columns?

Answer 11

Gracile fasciculus (medial) Cuneate fasciculus (lateral)

Question 12

Label the following diagram:

Answer 12

Question 13

What are the mammillary bodies?

Answer 13

Part of the limbic system.

Inferior part of the hypothalamus.

Question 14

Where is the pituitary stalk?

Answer 14

Immediately behind optic chiasm, anteroinferior view of the brainstem.

Question 15

Where does the oculomotor nerve (CNIII) emerge?

Answer 15

Midbrain.

Arises between cerebral peduncles- interpeduncular fossa.

Question 16

What is the function of the oculomotor nerve (CNIII)?

Answer 16

Supplies majority of extrinsic eye muscles

Question 17

What are the cerebral peduncles?

Answer 17

Surface representation of main motor tracts- corticospinal.

Structural and functional role. Fibre tract.

Hold cortex onto brainstem.

Question 18

Which cranial nerve emerges from the pons?

Answer 18

Trigeminal nerve (CNV)

Question 19

Which cranial nerves emerge from the pontomedullary junction (medial to lateral) and what are their functions?

Answer 19

Abducens (CNVI)- supplies lateral rectus muscle of the eye, responsible for abduction.

Facial nerve (CNVII)- supplies muscles of facial expression.

Vestibulocochlear nerve (CNVIII)- balance and hearing, innervates the inner ear in the temporal bone.

Question 20

Which cranial nerves emerge from the lateral aspect of the medulla?

Answer 20

Glossopharyngeal nerve (CNIX)- tongue and pharyngeal movements.

Vagus nerve (CNX)- main parasympathetic nerve to viscera.

Accessory nerve (CNXI)- supplies sternocleidomastoid and trapezius muscles.

Question 21

What is the function of the hypoglossal nerve (CNXII)?

Answer 21

Supplies muscles of the tongue.

Question 22

What are the pyramids?

Answer 22

Basis of contralateral motor control

90-95% of fibres cross over at base of medulla at the pyramidal decussation.

Continuation of corticospinal tract.

Question 23

How are the spinal nerves functionally classified?

Answer 23

General somatic afferent (GSA)- sensation from skin and mucous membranes in the head and neck

General visceral afferent (GVA)- sensation from GI tract, heart, vessels and lungs

General somatic efferent (GSE)- muscles for eye and tongue movements

General visceral efferent (GVE)- preganglionic parasympathetic

Special somatic afferent- vision (CNII), hearing and equilibrium (CNVIII)

Special visceral afferent- smell (olfactory) and taste

Special visceral efferent- muscles involved in chewing, facial expression, swallowing, vocal sounds and turning head (CNXI)

Question 24

Touch sensation from the skin on the forehead is of what functional classification?

Answer 24

General somatic afferent

Question 25

In the embryonic spinal cord, how are the functionally classified cranial nerves arranged?

Answer 25

GSA and GVA are in the alar plate, GVE and GSE are in the basal plate. Basal and alar plates are divided by the sulcus limitans. Dorsal root enters alar plate. Ventral root enters basal plate.

Question 26

In the embryonic rhombencephalon, how are the functionally classified cranial nerves arranged?

Answer 26

GSE and GVE more medial. GVA and GSA more lateral. Alar plate splits and opens up when reaching the brainstem (rhombencephalon).

Question 27

Label the following diagram:

Answer 27

Question 28

Label the following diagram:

Answer 28

Question 29

Label the following diagram:

Answer 29

Question 30

Label the following diagram:

Answer 30

Question 31

Label the following diagram:

Answer 31

Question 32

What is lateral medullary syndrome?

Answer 32

Thrombosis of vertebral artery or PICA- supply lateral medulla. Symptoms: - vertigo - ipsilateral cerebellar ataxia - ipsilateral loss of pain/thermal sense (face) - Horner's syndrome - hoarseness, difficulty in swallowing - contralateral loss of pain/thermal sense (trunk and limbs)

Question 33

Which cranial nerve nucleus receives sensory information concerning taste?

Answer 33

Nucleus solitarius