Lab 4 Cranial Nerves

Question 1

What are the five functional components of CNs 9 & 10:

Answer 1

1) Provide cutaneous innervation for the area behind the ear (IX) and the posterior wall of the external auditory meatus (X).
2) Provide sensory innervation for: mucous membrane of posterior 1/3 of the tongue, the tonsils, and upper pharynx and Eustachian tube (IX) & the pharynx, larynx, trachea, esophagus, and viscera (X)
3) IX and X convey taste impulses to the nucleus solitarius of medulla: for posterior 1/3 of tongue (IX) & for mucosa of the pharyngeal wall and the epiglottis (only children) (X)
4) Preganglionic parasympathetic neurons; The # of neurons for IX are few, while for X a distinct nucleus is observed, DORSAL MOTOR NUCLEUS OF X: the inferior salivatory nucleus gives rise to the preganglionic parasympathetics to the Otic ganglion (the Otic Ganglion innervates the Parotid Gland) (IX), & the dorsal motor nucleus of the vagus provides preganglionic parasympathetic neurons to much of the viscera (X).
5) Innervation of intrinsic muscles of the larynx. IX is the nerves to stylopharyngess muscle, while X is the nerve to intrinsic muscles of Pharynx and Larynx. The cells of origin for both of these components are located in the Nucleus Ambiguus of the medulla. These are typical LMNs and lesions cause IPSILATERAL PARALYSIS of innervated muscles.

Question 2

Where does the Spinal Accessory Nerve (CN XI) arise from?

What do they innervate?

Answer 2

• The motor neurons in the dorsal edge of the ventral horn of C2-C4.
• Sternocleidomastoid and trapezius muscles

Question 3

Describe the path of the CN XI:

Answer 3

• Axons leave the spinal cord,
• separate from ventral root and ascend along the pia to enter foramen magnum and
• then exit via the jugular foramen along with the Glossopharyngeal and Vagus Nerves

Question 4

What does integrity of the CN XI test?

Answer 4

the strength of the SCM and Trapezius muscles

Question 5

Describe the one component of the Hypoglossal nerve (XII):

Answer 5

Nerve supplies the motor innervation to the intrinsic and extrinsic muscles of the tongue.

Question 6

What is the origin of the Hypoglossal Nucleus?

Answer 6

hypoglossal nucleus located in the medulla

Question 7

Where does CN XII exit in the medulla?

Answer 7

rootlets of XII exit between the olive and the pyramids

Draw this!

Question 8

What nerve is the motor nerve to the muscles of facial expression?

Answer 8

Facial Nerve (VII)

Question 9

Describe the 4 components of CN VII:

Answer 9

1) Lower Motor Neurons from the motor nucleus of the facial nerve innervate the ipsilateral muscles of facial expression.
2) Preganglionic Parasympathetic neurons control the lacrimal gland and the submandibular and sublingual glands.

Question 10

Describe the 4 components of CN VII:

Answer 10

1) Lower Motor Neurons from the motor nucleus of the facial nerve innervate the ipsilateral muscles of facial expression.
2) Preganglionic Parasympathetic neurons control the lacrimal gland and the submandibular and sublingual glands.
3) Taste afferents from the ipsilateral anterior two thirds of the tongue. These afferents synapse in the rostral end of the Nucleus Solitarius. These fibers are carried in Chorda Tympani.
4) Cutaneous Sensation from the external auditory meatus end in the spinal nucleus