Organisation Of Brainstem And Cranial Nerves

Question 1

Definition of brainstem

Answer 1

Part of the CNS, exclusive of the cerebellum, that lies between the cerebrum and spinal cord

Question 2

What are the 3 major divisions of the brainstem from top to bottom

Answer 2

Midbrain
Pons
Medulla

Question 3

What is the floor of the 4th ventricle

Answer 3

Pons

Question 4

Which gland is midline and releases melatonin and is important in circadian rhythm

Answer 4

Pineal gland

Question 5

What is the superior colliculus important for?

Answer 5

Coordination of head and eye movements at the same time (watching tennis)

Question 6

What is the inferior colliculus important for?

Answer 6

Auditory reflexes (if there is a loud bang, you will look towards it)

Question 7

Which cranial nerve emerges from the back of the brainstem

Answer 7

Trochlear nerve (CN IV)

Question 8

What does the CN IV supply

Answer 8

One of the extrinsic muscles of the eye

Question 9

Which two main sensory pathways is the dorsal column involved in?

Answer 9

Touch and proprioception

Question 10

Why is the pons very easy to identify

Answer 10

It has transverse fibres running across it which makes it easy to identify

Question 11

What is at the top of the midbrain

Answer 11

Optic chiasm- where optic nerves converge

Question 12

What is immediately behind the optic chiasm

Answer 12

Pituitary stalk (infundibulum)

Question 13

What is behind the infundibulum

Answer 13

Inferior part of the hypothalamus- mamillary bodies

Question 14

Which system do mamillary bodies belong to

Answer 14

Limbic system

Question 15

Which cranial nerve emerges just above the transverse fibres of the pons

Answer 15

Oculomotor nerve (CN III)

Question 16

What is the function of CN III

Answer 16

Main nerve involved in eye movements

Question 17

What is the cerebral peduncle

Answer 17

The main motor fibres coming from the motor cortex down to the spinal cord

Question 18

What is the only cranial nerve that emerges from the lateral part of the pons

Answer 18

Trigeminal (CN V)

Question 19

What is the function of CN V

Answer 19

Touch and sensation throughout the head and neck

Question 20

How many cranial nerves emerge at the pontomedullary junction

Answer 20

Three-
• Most medially (the long one in the middle) -Abducens (CN VI)
• Moving laterally (the nerve the arrow is pointing to) -Facial (CN VII)
. Most lateral of the three -Vestibulocochlear (CN VIII)

Question 21

What is the role of the abducens (CN VI)

Answer 21

Supplies the laterus rectus muscle- last extrinsic muscle of the eye and causes abduction from the midline

Question 22

What is the role of the facial (CN VII)

Answer 22

Innervates the facial muscles involved in expression

Question 23

What is the role of the vestibulocochlear (CN VIII)

Answer 23

Involved in balance and hearing

Question 24

What is Bell’s palsy

Answer 24

Dysfunction of the facial nerve causes a loss of facial muscle tone

Question 25

What is the role of the glossopharyngeal (CN IX)

Answer 25

Sensory and motor innervation of the tongue and pharynx

Question 26

What is the role of the vagus (CN X)

Answer 26

Main parasympathetic nerve that projects down into the viscera

Question 27

What is the role of the accessory (CN XI)

Answer 27

Supplies the sternocleidomastoid (allows turning of the head) and trapezius

Question 28

What is the role of the hypoglossal (CN XII)

Answer 28

Supplies the musculature of the tongue

Question 29

What is the point where 90-95% of fibres cross over at the base of the medulla called?

Answer 29

Pyramidal decussation

Question 30

What are the four functional subtypes of the cranial nerves

Answer 30

General somatic afferent General visceral afferent General somatic efferent General visceral efferent

Question 31

What is the general somatic afferent for?

Answer 31

Sensation from skin and mucous membranes

Question 32

What is the general visceral afferent for?

Answer 32

Sensation from GI tract, heart, vessels and lungs

Question 33

What is the general somatic efferent for?

Answer 33

Muscles for eye and tongue movements

Question 34

What is the general visceral efferent for?

Answer 34

Preganglionic parasympathetic

Question 35

Which spinal cord root does information go into and leave from

Answer 35

Enters- Dorsal | Leaves- Ventral

Question 36

Are motor nuclei for cranial nerves medial or lateral>

Answer 36

Medial, sensory are lateral

Question 37

What does the midbrain look like

Answer 37

Mickey mouse

Question 38

What can you see that lets you know that you're in the midbrain

Answer 38

Cerebral aqueduct

Question 39

What is the most obvious sign that you're in the midbrain (dopaminergic neurones)

Answer 39

Substantia nigra

Question 40

Why is the substantia nigra black?

Answer 40

In normal metabolism, dopaminergic neurones produce neuromelanin which is a pigment that gives its black colour

Question 41

What is just underneath the cerebellum

Answer 41

The pons- in the region of the 4th ventricle

Question 42

What are cerebral peduncles for?

Answer 42

Holding cerebrum onto brainstem

Question 43

What is the main cerebral peduncle?

Answer 43

Middle cerebellar peduncle

Question 44

Which structure changes a lot as you go down the brain stem

Answer 44

Medulla

Question 45

What is the main feature of the medulla

Answer 45

Pyramids

Question 46

What is the inferior olivary nucleus

Answer 46

Bit of a bulge in the side of the medulla- connected to the cerebellum and involved in fine motor movements

Question 47

At the junction of the medulla with the spinal cord, what is the cross section like?

Answer 47

Very round

Question 48

What is the smaller dorsal column

Answer 48

Gracilis- sensory information from lower limb

Question 49

What is the cuneatus

Answer 49

It is more lateral than the gracilis and provides sensory information from the upper limb

Question 50

What can be seen in the cross section of the lower medulla (2 things)

Answer 50

Central canal and pyramidal decussation

Question 51

What causes lateral medullary syndrome

Answer 51

Thrombosis of vertebral artery or posterior inferior cerebellar artery

Question 52

What are the symptoms of lateral medullary syndrome

Answer 52

Vertigo, ipsilateral cerebellar ataxia, ipsilateral loss of pain and Horner's syndrome

Question 53

What is Horner's syndrome?

Answer 53

Loss of sympathetic innervation to head and neck