Cranial Nerves_2

Question 1

Describe the course of the facial motor nerve, and how it innervates motor muscles of the face.

Answer 1

Facial motor nucleus is located in the mid to lower pons. It is at the same level as the abducens but makes a genu around the abducens around the facial colliculi. It leaves ventral laterally (more lateral to the abducens). It makes an internal genu, then goes through the internal acoustic meatus. It then travels through the auditory canal, then through the facial canal (the facial canal is medial to the middle ear). It then goes through the stylomastoid foramen, then between the stylohyoid muscle and the posterior belly of the digastric (innervates them), travels with the auriculotemporal nerve in the parotid gland (does not innervate but separates the gland into superficial and deep divisions). After it exits the parotid gland, ti gives rise to 5 motor branches: Temporal, Zygomatic, Buccal, Mandibular, Cervical. It also innervates the stapedius.

Question 2

How does the facial nerve innervate the lacrimal gland?

Answer 2

The salivary nucleus of the facial nerve gives rise to the greater petrosal superficial nerve. This nerve synapses on the pterygopalantine ganglion (sphenopalantine ganglion). From there, the postganglionic parasympathetic fibers from cell bodies in the ganglion is now part of the zygomaticofacial branch of V2. One branch will then travel onto the lacrimal branch of V1, and another will travel with the palatine branch of the trigeminal onto the minor salivary glands of the palate.

Question 3

How does the facial nerve innervate the submandibular and sublingual glands?

Answer 3

The salivary nucleus of the facial nerve gives rise to the chorda tympani. The chorda tympani travels with the facial motor nerve, goes through the IAM, but turns before it goes through the stylomastoid foramen. It synapses on the submandibular ganglion, and from there, the post-ganglionic parasympathetic nerves travel with the lingual nerve of V3 and innervate the sublingual and submandibular gland.

Question 4

Explain how we taste from the anterior 2/3rds of our tongue.

Answer 4

The anterior 2/3rds of our tongue has sensory fibers (chorda tympani) that travel with the lingual nerve of V3 of trigeminal. The fibers pass through the geniculate ganglion (where the primary sensory neurons are..but they don’t synapse here), and then synapse in the nucleus solitarious.

Question 5

Describe Bell’s Palsy

Answer 5

All divisions of facial nerves are impaired. Unilateral face weakness. Hypercusis can occur (stapedius muscle weakness) and dry eyes (decreased lacrimation).

Question 6

Why would Bell’s Palsy cause decreased lacrimation and hypercusis? *(a health condition characterized by increased sensitivity to certain frequency and volume ranges of sound).

Answer 6

Bell’s Palsy occurs due to impared facial nerves. If facial nerve is impaired, then the salivatory nucleus will be impared. The greater petrosal nerve arises from the facial nerve, goes through the IAM, synapses on the pterygopalantine ganglion. From there, the postganglionic parasympathetic fibers travel with the zygomaticofacial V2, then the lacrimal V1 (to lacrimal gland) or palatine branch of V (to minor salivary gland of palate). Hypercusis could occur because the facial nerve also innervates the stapedius muscle.

Question 7

Where does the vestibulocochlear nerve exit the brain stem?

Answer 7

It exits at the PMJ (8 year old likes PB+J sandwiches). It is lateral to the facial nerve.CN VII along with CN VIII exits through the IAM.CN VII is somatosensory, so sensory fibers from the cochlea go to the spiral ganglion then through the auditory canal, go to the PMJ then synpse at the dorsal ventrical cochlear nuclei. Sensory fibers coming from the vestibular apparatus go to the scarps ganglia, travel through the auditory canal, and go to the PMJ then synapse on the dorsal and ventral cochlear nucleus.

Question 8

How is the stylopharyngeus muscle innervated?

Answer 8

It is innervated by nucleus ambiguus nucleus of the glossopharyngeal nerve. The nucleus ambiguus nerve provides skeletal muscle innervation to the stylopharyngeus. This muscle elevates the pharynx, larynx, and dilates the pharynx so that a bolus can pass through.

Question 9

How is the parotid gland innervated?

Answer 9

The parotid gland is innervated by the glossopharyngeal nerve. Salivary nucleus gives off the lesser superficial petrosal nerve which synapses in the otic ganglion. From there, the postsynapatic parasympathetic fibers innervate the parotid gland.

Question 10

What is the solidarity nucleus role in XI?

Answer 10

1/3 of the posterior tongue (taste- special visceral sensory) and the carotid sinus and baroreceptors (general visceral sensory) have sensory fibers that are conveyed by the inferior glossopharyngeal ganglion which synapse in the solitarity nucleus of XI.

Question 11

How is general somatic sensory (pain/temp) conveyed from the pharynx, and 1/3 posterior portion of the tongue?

Answer 11

General somatic sensory from the posterior 1/3 of the tongue and pharynx, larynx, are conveyed by superficial and inferior (jugular) glossopharyngeal ganglion. Then synapse in the trigeminal spinal nucleus.

Question 12

What nerve (nucleus) is responsible for the gag reflex?

Answer 12

Vagus:Nucleus ambiguus provides motor innervation to the pharyngeal muscles (swallowing and gag reflex) and laryngeal muscles.

Question 13

What nerve is responsible for conveying sensory information from the baroreceptors and chemoreceptors of the aortic arch?

Answer 13

Vagus nerve.Visceral sensory (general) information from the aortic arch covey sensory information to the nodosal ganglion, which then go to the solitary nucleus. Taste from the pharynx and epiglottis (visceral special information) also covey sensory information to the solitary nucleus.

Question 14

General sensation (pain and temp) from the tongue, pharynx and a small region near the external auditory meatus convey their information where and then synaps where?

Answer 14

general somatic sensation like pain and temp from the tongue, pharynx and a small region of the external auditory meatus convey their information to superior vagal ganglion, then synpase at the trigeminal spinal nucleus

Question 15

A branch of the vagus, the ____ ____ nerve loops back upward from the thoracic cavity to control all intrinsic laryngeal muscles (except for the cricothyroid, which is innervated by the ___ ___ nerve).

Answer 15

recurrant laryngeal nerve loops back upward from the thoracic cavity to control all intrinsic laryngeal muscles (except the cricothyroid , which is innervated by the superior laryngeal nerve).

Question 16

What might cause unilateral vocal cord paralysis and hoarseness?

Answer 16

injury to the recurrant laryngeal nerve

Question 17

Where does spinal accessory nerve arise from?

Answer 17

The first 5 or 6 cervical segments of the spinal cord (NOT FROM THE BRAIN STEM)

Question 18

What does the spinal accessory nerve innervate?

Answer 18

SCM and trapezius

Question 19

Where does XI exit?

Answer 19

jugular foramen

Question 20

The left sternomastoid turns the head ____

Answer 20

right

Question 21

The trapezius is involved in ___ the shoulders.

Answer 21

elevating

Question 22

With pressure on the shoulder from above, trapezius can be tested by having the patient ____ the shoulders.With pressure against the side of the head (black arrow), ____can be tested by having the turn the head up and toward the side (white arrow

Answer 22

With pressure on the shoulder from above, trapezius can be tested by having the patient elevate the shoulder (shrugging the shoulders).With pressure against the side of the head (black arrow), SCM can be tested by having the turn the head up and toward the side (white arrow

Question 23

______ nucleus exits between the medial lemniscus and the inferior olive and innervates 3 tongue muscles (all except palatoglossal muscle).

Answer 23

Hypoglossal nucleus exits between the medial lemniscus and the inferior olive and innervates 3 tongue muscles (all except palatoglossal muscle).

Question 24

Lower motor lesions of CN XI will cause what?

Answer 24

some ipsilateral weakness of shoulder shrug of arm elevation.

Question 25

Upper motor lesion of CN XI will cause what?

Answer 25

cause deficits in head turning, toward the side opposite the lesion.

Question 26

What innervates the muscles of the tongue?

Answer 26

The hypoglossal nerve.

Question 27

Where does the hypoglossal nerve exit?

Answer 27

Between the pyramid and inferior olivary sulcus. The nerve exists through its own foramen, hypoglossal foramenm and provides somatic motor innervation to all intrinsic and extrinsic tongue muscles except for the palatoglosses, which is innervated by CN X.

Question 28

If you had contralateral tongue weakness, where was the lesion?

Answer 28

In the primary motor cortex or internal capsule.

Question 29

If you had ipsilateral tongue weakness, where was your lesion?

Answer 29

It was in the hypoglossal nucleus,

Question 30

A small branch of the facial nerve provides general somatic sensation for a region near the external auditory meatus that lies adjacent to similar regionns supplied by CN IX, and X. The somatosensory fibers for __, ___, ___ and ___ all synapse in the trigeminal nuclei.

Answer 30

V, VII, IX, and X

Question 31

__ – Mediates leg extension and the Patellar Reflex__ – Dorsiflexion at the ankle __- Mediates Plantar Flexion at the ankle and the Achilles tendon reflex.

Answer 31

L4 – Mediates leg extension and the Patellar ReflexL5 – Dorsiflexion at the ankle S1- Mediates Plantar Flexion at the ankle and the Achilles tendon reflex.

Question 32

__ –Mediates arm abduction__-__ – mediates flexion at the elbow and the Biceps tendon reflex__ – wrist extension__ – elbow extension and the triceps reflex

Answer 32

C5 –Mediates arm abductionC5-C6 – mediates flexion at the elbow and the Biceps tendon reflexC6 – wrist extensionC7 – elbow extension and the triceps reflex

Question 33

___fibers are related to receptors for pain temperature and mechanical receptors in the skin, muscles and joints.___fibers are related to receptors in visceral structures.___fibers are preganglionic autonomic fibers.___fibers innervate skeletal muscle (these are axons of alpha and gamma motor neurons)

Answer 33

General Somatic Afferent (GSA)fibers are related to receptors for pain temperature and mechanical receptors in the skin, muscles and joints.General Visceral Afferent (GVA)fibers are related to receptors in visceral structures.General Visceral Efferent (GVE)fibers are preganglionic autonomic fibers.General Somatic Efferent (GSE)fibers innervate skeletal muscle (these are axons of alpha and gamma motor neurons)

Question 34

The ventral root carries ___ axons out to the spinal nerve to innervate skeletal muscle.The dorsal root carries ___ axons in to the spinal cord from the spinal nerve.

Answer 34

The ventral root carries motor axons out to the spinal nerve to innervate skeletal muscle.The dorsal root carries sensory axons in to the spinal cord from the spinal nerve.

Question 35

___ Matter is enriched with nerve cell bodies or soma.___ Matter contains columns of axons ascending and descending the spinal cord.

Answer 35

Gray Matter is enriched with nerve cell bodies or soma.White Matter contains columns of axons ascending and descending the spinal cord.

Question 36

Spinal nerves are ___ nerve fibers that that contain both sensory and motor fibers and you can characterize the fiber types based upon the information carried.

Answer 36

Spinal nerves are mixed nerve fibers that that contain both sensory and motor fibers and you can characterize the fiber types based upon the information carried.

Question 37

Cell bodies for sensory fibers are located in the ____nervous system in a collection of ganglia known as the dorsal or posterior root ganglia.

Answer 37

Cell bodies for sensory fibers are located in the peripheral nervous system in a collection of ganglia known as the dorsal or posterior root ganglia.

Question 38

___ matter surrounds the ___matter of the spinal cord and are characterized by anatomical position. This white matter consists collections of axons traveling cranially and caudally and are known as anterior, posterior, and lateral funiculi

Answer 38

White matter surrounds the gray matter of the spinal cord and are characterized by anatomical position. This white matter consists collections of axons traveling cranially and caudally and are known as anterior, posterior, and lateral funiculi

Question 39

The cervical spinal cord has a large diameter because all ascending and descending fiber tracts go through the cervical cord.Sensory fibers are successively added to the white matter tracts at progressively ____ levels of the cord.More caudally, many of the ____ motor projections from the brain have terminated and are no longer present.

Answer 39

The cervical spinal cord has a large diameter because all ascending and descending fiber tracts go through the cervical cord.Sensory fibers are successively added to the white matter tracts at progressively higher levels of the cord.More caudally, many of the descending motor projections from the brain have terminated and are no longer present.

Question 40

Where are the expansions located in the spinal cord?

Answer 40

C5-T1L1 - S2

Question 41

The spinal cord is covered by a series of coverings.From out to in: ___ –> ___ –> ___Appreciate the Dura Mater. Note the very real epidural space that exists between the __ __ and the __.There is a potential space between the arachnoid and the Dura (___ space), but a real space between the arachnoid and the pia mater (__ space)

Answer 41

The spinal cord is covered by a series of coverings.From out to in: Dura –> Arachnoid –>Pia.Appreciate the Dura Mater. Note the very real epidural space that exists between the vertebral column and the dura.There is a potential space between the arachnoid and the Dura (subdural space), but a real space between the arachnoid and the pia mater (subarachinoid space).

Question 42

The spinal cord ends on __-___but the rootlets that eventually form spinal nerves will continue to track inferiorly through the Vertebral column and exit the vertebral column through the appropriate intervertebral space. If you want to do a spinal tap, where should you enter?

Answer 42

The spinal cord ends on L1-2 but the rootlets that eventually form spinal nerves will continue to track inferiorly through the Vertebral column and exit the vertebral column through the appropriate intervertebral space.If you want to do a spinal tap you should enter L4-L5

Question 43

There are 31 spinal nerves emerging from the spinal cord. __ Cervical, __ Thoracic, __Lumbar, __ Sacral and __Coccygeal N.

Answer 43

•There are 31 spinal nerves emerging from the spinal cord. 8 Cervical, 12 Thoracic, 5 Lumbar, 5 Sacral and 1 Coccygeal N.

Question 44

•The Spinal Cord terminates at __-__ vertebral levels.•The Spinal Cord is surrounded by 3 layers of connective tissue. The __,the ___, and the ___.

Answer 44

•The Spinal Cord terminates at L1-L2 vertebral levels.•The Spinal Cord is surrounded by 3 layers of connective tissue. The pia, the arachnoid, and the dura.

Question 45

•Specializations in the Pia and Dura Mater stabilize the cord within the vertebral column via the ____ ligaments, the filum terminale internum, and the filum terminale externum.

Answer 45

•Specializations in the Pia and Dura Mater stabilize the cord within the vertebral column via the denticulate ligaments, the filum terminale internum, and the filum terminale externum.

Question 46

Dorsal horn – sensoryVentral horn – motorIntermediolateral cell column – preganglionic autonomic __ - ___.

Answer 46

Dorsal horn – sensoryVentral horn – motorIntermediolateral cell column – preganglionic autonomic T1-L2

Question 47

Can you differentiate between different regions of the spinal cord?

Question 48

Lower ___segments have an enlarged ventral horn, which contains neurons for innervating the forelimb muscles. The posterior columns are subdivided into the fasciculus gracilis (conveys sensations from legs and lower trunk) and the fasciculus cuneatus (conveys sensations from upper trunk and arms).The lower thoracic cord has a lateral horn and small ventral horns. Laminae VII contains a prominent cluster of large neurons called the dorsal nucleus of ___. Below T6, only the fasciculus gracilis is present in the posterior columns.The ____ cord has an enlarged ventral horn, which contains motor neurons that innervate the leg muscles.

Answer 48

Lower cervical segments have an enlarged ventral horn, which contains neurons for innervating the forelimb muscles. The posterior columns are subdivided into the fasciculus gracilis (conveys sensations from legs and lower trunk) and the fasciculus cuneatus (conveys sensations from upper trunk and arms).The lower thoracic cord has a lateral horn and small ventral horns. Laminae VII contains a prominent cluster of large neurons called the dorsal nucleus of Clarke. Below T6, only the fasciculus gracilis is present in the posterior columns.The lumbar cord has an enlarged ventral horn, which contains motor neurons that innervate the leg muscles.