Clinical anatomy - Head, Neck and Spine

Question 1

how many cranial nerves are there?

Answer 1

12

Question 2

cranial nerve 1

Answer 2

oflactory

Question 3

cranial nerve 2

Answer 3

optic

Question 4

which nerves are the only ones which don’t originate from the brainstem?

Answer 4

olfactory (1) and optic (2)

Question 5

where do the nuclei for cranial nerves 3 and 4 lie?

Answer 5

midbrain

Question 6

where do the nuclei for cranial nerves 5, 6, 7 and 8 predominantly lie?

Answer 6

pons

Question 7

where do the nuclei for cranial nerves 9, 10, 11 and 12 lie predominantly?

Answer 7

medulla oblongata

Question 8

for each cranial nerve, what do I need to know?

Answer 8

CNS pathway above them and anatomical course, individual functions and how to test them, clinical relevance of the examination findings

Question 9

which part of which bone supports the olfactory bulb?

Answer 9

cribriform plate of the ethmoid bone

Question 10

through which foramen does the olfactory nerve (1) run into the cranial cavity ?

Answer 10

foramina of the cribiform plate

Question 11

what is the function of the olfactory nerve (1)?

Answer 11

It relays sensory data to the brain, and it is responsible for the sense of smell.

Question 12

what is the function of the optic nerve? Where does it run through?

Answer 12

transfer visual information from the retina to the vision centers of the brain via electrical impulses. Runs through optic canal

Question 13

what is the third cranial nerve?

Answer 13

occulomotor

Question 14

what is the function of the oculomotor nerve? Where does it enter the orbit?

Answer 14

enters the orbit via the superior orbital fissure and innervates extrinsic eye muscles that enable most movements of the eye and that raise the eyelid.

Question 15

where does the abducent nerve innervate?

Answer 15

lateral rectus muscle of the eye

Question 16

where does the trochlear nerve innervate?

Answer 16

innervates only a single muscle: the superior oblique muscle of the eye

Question 17

which is the fourth cranial nerve?

Answer 17

trochlear

Question 18

which is the fifth cranial nerve?

Answer 18

trigeminal

Question 19

which is the sixth cranial nerve?

Answer 19

abducent

Question 20

what does the trigeminal nerve innervate?

Answer 20

responsible for sensation in the face and motor functions such as biting and chewing; it is the largest of the cranial nerves.

Question 21

where does the facial nerve innervate?

Answer 21

facial muscles

Question 22

where does the intermediate nerve innervate?

Answer 22

is the part of the facial nerve (cranial nerve VII) located between the motor component of the facial nerve and the vestibulocochlear nerve (cranial nerve VIII). It contains the sensory and parasympathetic fibers of the facial nerve. Motor - submandibular, sublingual, lacrimal glands. Taste - anterior 2/3 of tongue in the soft palate. Sensory - external auditory meatus and nasopharynx

Question 23

which is the seventh cranial nerve?

Answer 23

facial nerve

Question 24

which is the eighth cranial nerve? And its function?

Answer 24

vestibulocochlear transmits sound and equilibrium (balance) information from the inner ear to the brain.

Question 25

which is the ninth cranial nerve? And its function?

Answer 25

glossopharyngeal, It receives general somatic sensory fibers (ventral trigeminothalamic tract) from the tonsils, the pharynx, the middle ear and the posterior 1/3 of the tongue. It receives special visceral sensory fibers (taste) from the posterior 1/3 of the tongue.

Question 26

which is the tenth cranial nerve? And its function?

Answer 26

vagus The most important function of the vagus nerve is afferent, bringing information of the inner organs, such as gut, liver, heart, and lungs to the brain. This suggests that the inner organs are major sources of sensory information to the brain.

Question 27

which is the eleventh cranial nerve? And its function?

Answer 27

accessory - Sternocleidomastoid and Trapezius

Question 28

which is the twelfth cranial nerve? And its function?

Answer 28

hypoglossal - provides motor control of the extrinsic muscles of the tongue: genioglossus, hyoglossus, styloglossus, and the intrinsic muscles of the tongue. These represent all muscles of the tongue except the palatoglossus muscle. The hypoglossal nerve is of a general somatic efferent (GSE) type.

Question 29

where is sense of smell detected?

Answer 29

olfactory receptors in the nasal epithelium

Question 30

where does the sensory information from the olfactory nerve reach?

Answer 30

primary olfactory cortex in the temporal lobe of the brain

Question 31

what is anosmia

Answer 31

loss of sense of smell

Question 32

what causes temporary anosmia?

Answer 32

locked nose from a common cold and other upper respiratory tract infections

Question 33

what causes permanent anosmia?

Answer 33

severe head injuries, or tumours that run along the olfactory nerves intracranial path. Also progressive anosmia may occur in neuro degenerative diseases, such as Alzheimer’s disease and some other brain disorders (such as multiple sclerosis).

Question 34

what is the pupillary light reflex?

Answer 34

controls the size of the pupils in response to changes in the strength of light that lands on the retina of the eye.

Question 35

which three limbs does each pupillary light reflex have?

Answer 35

Each pupillary light reflex has an afferent limb (optic nerve) and two efferent limbs (parasympathetic fibres along the oculomotor nerves).

Question 36

where is light turned into impulses

Answer 36

rods and cones of retina

Question 37

how do impulses from light reach the cranial cavity?

Answer 37

These impulses are the transmitted from the retina through the intracranial cavity to the brain by the optic nerve (CN II) through the optic canal.

Question 38

which part of the brain do the optic nerve impulses travel to?

Answer 38

These impulses then pass through the visual pathway within the brain to the primary visual cortex where we appreciate the vision.

Question 39

how does the path of the pupillary light reflex differ to the visual pathway?

Answer 39

pupillary light reflex takes a different and shorter path than the whole visual pathway, as the reflex does not require our appreciation of the light, it works independent of our thought and command.

Question 40

which is the afferent limb of the pupillary light reflex?

Answer 40

The optic nerve is the afferent limb of the pupillary light reflex, sending the sensory impulses via mid brain nuclei to trigger motor impulses through parasympathetic axons running along the oculomotor nerves (efferent limb) to innervate the pupillary sphincter muscles in the eye leading to pupillary constriction (miosis) of both the ipsilateral pupil (same side) and the contralateral pupil (other side)

Question 41

how is the pupillary light reflex tested?

Answer 41

This pathway/reflex is tested by shining a light in each eye individually and because of the two efferent limbs, there is not only a direct pupillary reflex but also a consensual pupillary light reflex.

Question 42

Outline the steps of the test for the pupillary light reflex

Answer 42

1. Ask the patient to look at a distant target 2. Inspect the pupils for size, shape and colour and any presence of ptosis (drooping of eye lid) 3. S​hine one eye with a penlight - observe for the pupillary constriction in the same eye (ipsilateral) 4. T​ake away the light for a few seconds 5. S​hine the penlight in the same eye - observe the pupillary constriction in the other eye (consensual)

Question 43

What is the clinical relevance for testing for the pupillary light reflex?

Answer 43

Direct and consensual pupillary light reflexes are tested to assess the integrity the function of both optic and oculomotor nerves. An Abnormal pupillary reflex can be caused by optic nerve damage, oculomotor nerve damage, brainstem injury, and depressant drugs.