Week 1 - H - Anatomy 4 - Cranial nerve anatomy and testing

Question 1

Name the cranial nerves, their nuclei and their fibre types (modalities)

Answer 1

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Question 2

What is the only motor part of the trigeminal nerve?

Answer 2

The mandibular division of the trigeminal nerve is the motor part

Question 3

What is the only cranial nerve not to arise from the brain? What cranial nerves do not arise anteriorly?

Answer 3

The spinal accessory nerve arises from the anterior horns of spinal cord segements C1-5 The trochlear nerve arises from the midbrain posteriorly The vestibulocochlear nerve arises laterally

Question 4

What does the intracranial part of the cranial nerve course refer to?

Answer 4

This refers to between the point the connection to the CNS and their respective base of skull foraminae

Question 5

What is the location of the intracranial nerves?

Answer 5

Olfactory and optic - forebrain Oculomotor and trochlear - midbrain Trigeminal - pons Abducent, facial and vestibulocochlear - pontomedullary junction Glossopharyngeal and vagus - medulla Spinal accessory - anterior horns of spinal cord segements C1-5 Hypoglossal - midline of medulla

Question 6

What are the three divisions of the trigeminal nerve? Which are sensory and which are motor?

Answer 6

Ophthalmic nerve (CN V1) - Superior orbital fissure - sensory Maxillary nerve (CNV2) - foramen rotundum - snesory Mandibular nerve (CN V3) - foramen ovale - sensory and motor

Question 7

What are the muscles which the mandibular nerve supplies?

Answer 7

Supplies the muscles of mastication mainly

Question 8

The trigeminal nerve supplies the areas of the face with sensory innervation What regions of the face are supplied by the opthalmic nerve?

Answer 8

Middle of head to upper eyelid, cornea and all conjunctiva Also the bridge and tip of the nose

Question 9

What area is supplied with sensory innervation by the maxillary nerve?

Answer 9

Skin of maxilla Skin off lower eyelid and ala of the nose Skin/mucosa of the upper lip

Question 10

What area is supplied with sensory innervation by the madnibular nerve? What supplies the angle of the mandible with sensory innervation?

Answer 10

Mandibular nerve - Skin over the mandible and tmj Angle of mandible supplied by the great auricular nerve (C2,3) and helix of ear

Question 11

It is important to remember that the trigeminal nerve also supplies deep structures with sensory innervaton and not just the superficial skin of the face Which nerve supplies the upper anterior and lower posterior nasal cavity? Which nerve supplies the ehtmoidal air cells, frontal sinus and sphenoid sinus with sensory innervation>

Answer 11

Upper anterior nasal cavity - ophthalmic nerve lower posterior nasal cavity - maxillary nerve Ethmoidal air cells, frontal and sphenoid sinus - ophthlmic nerve Maxillary sinus - maxillary nerve

Question 12

What supplies the anterior 2/3rds of the tongue with sensory innervation? What supplied the buccal mucosa with sensory innervation?

Answer 12

Anterior 2/3rds of the tongue - mandibular nerve Buccal mucose - mandibular nerve

Question 13

The trigeminal nerve as stated before supplies the muscles of mastication with motor innervation What are these muscles? Which are the jaw openers and which are the jaw closers? What other muscles are supplied with motor innervation by this nerve?

Answer 13

Mandibular division of the trigeminal nerve (CN V3) Masseter, temporalis, medial pterygoid - jaw closers Lateral pterygoid - jaw openers Also supplies the tensor veli palatini, tensor tympani, anterior belly of the digastric muscle, mylohoid

Question 14

Where does the tensor tympani attach? What doe the tensor veli palatini assist with?

Answer 14

Tensoy tympani attaches to the malleus Tensor veli palatini assists with the elevation of the soft palate

Question 15

What are the attachment points of the muscles of mastication?

Answer 15

Masseter - angle of mandible to zygomatic arch Temproalis - coronoid process of mandible to temporal fossa Medial pterygoid - medial side of mandible to pterygoid plates of sphenoid bone Lateral pterygoid - codyle of mandible and articular disc of TMJ to ptergoid plates of sphenoid bone

Question 16

When testing the sensory innervation of the trigeminal nerve, touch a cotton wool bud to the areas of the face with the patients eyes closed What branch of which trigeminal nerve is the afferent part of the corneal (blink)? What nerve is the efferent? WHat muscles causes eye closure?

Answer 16

Nasociliary branch of the ophthalmic division of the trigeminal nerve is afferent Facial nerve is the efferent part The orbiuclaris oculi causes the eye to close

Question 17

How is the motor function of the temporalis, masseter and lateral pterygoid tested?

Answer 17

Ask person to clench teeth and feel masseter and temporalis Ask patient to open jaw against resistance for the lateral pterygoid

Question 18

What are the different nerve fibres of the facial nerve? Where is its connection to the CNS? What is its course in the skull?

Answer 18

Special sensory, somatic sensory, motor and parasympathetics Enters the internal acoustic meatus in the temporal bone where it travels through the facial canal and exits the skull through the stylomastoid foramen Connects to the CNS at the pontomedullary junction

Question 19

The facial nerve’s (CNs VII) base of skull course through the petrous temporal bone: How does it provide taste to what protion of the tongue? What else does this nerve supply?

Answer 19

Provides taste to anterior 2/3rds of the tongue via the chorda tympani branch of the nerve which exits the skull via the petrotympanic fissure and hitches a ride on the lingual nerve Chorda tympani also provides parasympathetic innervation to the sublingual and submandibular glands

Question 20

What is the smallest muscle in the body? What is the function of this muscle? What inervates this muscle?

Answer 20

The stapedius Reduces stapes movement to protect the ear from excessive noise Innervated by facial nerve (CN VII)

Question 21

What are the branches that the facial nerve gives off to supply the muscles of facial expression? What are the muscles of facial expression?

Answer 21

Temproal branch Zygomatic branch Mainal mandibular branch Buccal branch Cervical branch Frontalis, orbicularis oculi, elevators of lips. orbicularis oris, buccinator, platysma

Question 22

What muscle of facial expression does each of these movements test? frown close eyes tightly - Which part of the orbicularis oculi is tested here? smile puff out cheeks Prevent drooling?

Answer 22

Frown - frontalis Close eyes tightly - orbital part of orbicularis oculi - palpebral part closes eyes gently, orbital part closes eyes tightly Smile - elevators of lips Puff out cheeks - orbicularis oris Prevent drooling - orbicularis oris

Question 23

What is the normally sharp demarcation between the lip and the adjacent normal skin?

Answer 23

This is the vermillion border

Question 24

Where does the glossopharngeal nerve arise in the brainstem? What are the different modalities? How does it exit the skull?

Answer 24

Glossopharngeal arises at the lateral aspect of the medulla Contains special sensory, sensory, motor, visceral afferents and parasympathetics Exits the skull via the jugular foramen

Question 25

Does the glossopharngeal supply the oro or naso pharynx with general sensory? What is the tonsil located in the palatine arches of the soft palate known as? Supplied by CN IX What is the tube connecting middle ear to lateral wall of nasopharynx knwon as?

Answer 25

Glossopharngeal suppleis naso and oropharyx ith general sensory innervation The palatine tonsil Supplies the Eustachian tube with sensory innervyion

Question 26

What does the glossopharngeal provide special sensory to? What does it provide with parasympathetics? What does it supply with visceral afferents?

Answer 26

Special sensory to vallate papillae (with taste buds) of the posteror 1/3rd of the tongue PArasympathetics to the parotid glands Visceral afferents to the carotid sinus and carotid body

Question 27

What supplied by the CN IX is sensitiive to arterial blood pressure? Where doe the nucleus for this sneosry afferent lie? What is the nuclei known as? What muscles is supplied by the glossopharnygeal nerve?

Answer 27

The carotid sinus Solitary nucleus located as the V shape in the medulla The stylopharngeus muscle is suppied with somatic motor from the glossopharyngeal

Question 28

What are the vagus nerve modalities? Where does it connect to CNS? Where does it exit the skull?

Answer 28

Special sensory, sensory, visceral afferents, motor, parasympathetics

Question 29

What does the vagus nerve travel within in the neck? What are the contents of this?

Answer 29

Travels within the carotid sheath Contains the internal jugular vein, common carotid artery and deep cervical lymphatics

Question 30

When does the right and left vagus become the recurrent laryngeal nerves?

Answer 30

• Right vagus arches rround the subclavian artery giving off the right recurrent laryngeal nerve right vagus continues on lateral aspect of aorta - Left vagus arches around the arch of the aorta giving left recurrent laryngeal nerve Left vagus continues on lateral aspect of trachea

Question 31

Where does the vagus nerve innervation off the abdomen end? What innervates the rest of the abdomen?

Answer 31

Ends at the splenic flexure Sacral spinal nerves innervate rest of abdomen

Question 32

How is the function of the vagus nerve tested? What other nerve is tested using this?

Answer 32

Ask patient to say ‘ahh’ and uvula should remian in midline Also tests the mandibular division of the trigeminl nerve as it supplies the tensor veli palatini

Question 33

If there is unilateral pathology when asking the patient to say ahhh, what way will the uvula go?

Answer 33

Uvula will go away from side of pathology ie damaged right vagus nerve, uvula will hang to the left

Question 34

Where is the origin of the spinal accessory nerve? What about the cranial accessory nerve? Where do the two meet? How does the spinal accessory nerve enter and exit the skull? What is its modality? What does it supply?

Answer 34

Spinal accessory originates in the anterior horn of spinal cord segments C1 - C5 and travels up through the foramen magnum Cranial accessory nerve originates in the nucleus ambiguus and joins with the spinal accessory nerve as they exit the skull via the jugular foramen Spinal accessory nerve is motor and supplies the sternocleidomastoid and trapezius muscles

Question 35

Where does the spinal accessory nerve come out at the soft tissue in the neck? What other nerves arise here?

Answer 35

Comes out at nerve point of the neck located at the midline of the posterior border of the sternocleidomastoid muscle Cervical plexus nerves also arise here

Question 36

The spinal accesory nerve and cervical plexus nerves arise deep to the posteriro border of the sternocleidomastoid before arising at the midpoint Which runs deep to trapezius muscles? How is CN XI tested?

Answer 36

The CN XI runs deep to trapezius Cervical plexus do not tested by asking patietn to shrug shoulder or turn head away

Question 37

Where does the hypoglossal nerve arise? Where is the hypoglossal nerve nuclei? Where does it exit the skull? What is the hypoglossal modality and what does it innnervate?

Answer 37

Arisses at the medial aspect of the medulla oblongata The nerve nuclei is the hypoglssal nuclei which runs the length of the medulla Exits the skull via the hypoglossal canal (anterior of foramen magnum) It is somatic motor and supplies all the intrinsic muscles of the tongue and all the extrinsic muscles of the tongue bar 1

Question 38

What are the four extrinsic tongue muscles? Which is not innervated by the hypoglossal nerve and what innervates it?

Answer 38

Genioglossus Stylogossus Hyoglossus Palatagolossus which is innervated by the vagus nerve

Question 39

How is pathology in the hypoglossal nerve tested for?

Answer 39

Ask patient to stick out the tongue If there is hypoglossal nerve pathology the tongue will fall towards the side of pathology If no pathology then will remain in the midline

Question 40

What are the two cranial nerves not to be routinely tested?

Answer 40

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