Cranial Nerves!!!

Question 1

where do sensory fibers have their cell bodies?

Answer 1

craniospinal ganglia

- dorsal root ganglia; nuclie/ganglia of specific cranial nerves

Question 2

GSA

Answer 2

1. receives enteroceptive impulses (pain, temperature, touch) from epithlium of ectodermal origin- all skin, dura mater, anterior 2/3rds of tongue
2. receives proprioceptive impulses from sensory endings in the body wall, tendons and joints

ECTODERMAL ORIGIN

Question 3

GVA

Answer 3

• Fibers carrying sensory impulses (usually pain) from visceral structures within body lined by epithelium
• posterior third of tongue, ducts of parotid gland, carotid sinus, middle ear, larynx, gut, etc.
• ENDODERMAL ORIGIN
• supply blood vessels, even though they are mesoderamlly derived

Question 4

SSA

Answer 4

Special somatic afferent: found only in cranial nn.

1. ear and eye (vision, hearing, equilibruim from outside)

Question 5

SVA

Answer 5

special visceral afferent - found only in cranial nn.

1. olfactory - smell
2. gustatory - taste
   * * named visceral b/c of the functional association of senation with digestive tract

Question 6

GSE

Answer 6

fibers conveying motor impulses to somatic skeletal muscles

• cell bodies located in ventral motor horn
• 3,4,6,11,12

Question 7

GVE

Answer 7

• cell bodies found in IMLCC
• autonomic fibers which innervate smooth m. of gut tube, blood vessels and cardiac muscle, and fibers for glandular secretion.
• symp: all spinal nn, ANS fibers
• PS: cranial nn: 3,7,9,10

Question 8

SVE

Answer 8

special visceral efferent

• nerves which innervate the skeletal muscles derived from the visceral arch mesoderm (branchiomeric/pharyngeal)
• muscles of mastication, facial expression, pharynx, palate and larynx
• no ANS control

Question 9

SSE

Answer 9

nerve fibers which influence sensory input to the ear - “selective hearing”
-8

Question 10

CN I

Answer 10

Olfactory n.
SVA
- sense of smell
- b/c it assists the body in preparing for eating by causing reflex salivation and an increase in gastric motility, designated as a visceral afferent n.

Question 11

CN II

Answer 11

Optic n.
SSA
- afferent fibers of the retina; primary receptor for the sense of sight

Question 12

CN III

Answer 12

Oculomotor: GSE, GVE-P

GSE: motor component innervates extra-ocular muscles of the eye which assist in rotational movment of the the eye

GVE-P: PS innervation of intra-ocular muscles of the eye responsible for changing the shape of the lens for accommodation and pupilary constriction; via inferior division of CN III

Question 13

CN IV

Answer 13

Trochlear: GSE

1. innervation of one extra-ocular eye muscle: superior oblique (“sad eye muscle” - turns eye down and out)
2. muscle utilizes a pulley to carry out its action: nerve carrier the name of “the pulley”

Question 14

CN V

Answer 14

Trigeminal: GSA, SVE

1. GSA: major sensory nerve of the head (innervates the scalp, most of face, all conjunctiva and provides all proprioceptive fibers to skeletal muscles of head)
2. SVE: motor innervation to skeletal muscles of pharyngeal arch origin- first arch: muscle of mastication (4), mylohyoid, anterior belly of digastric muscle, tensor vli palatinia and tensor tympani muscles.

note: does not contain GVE-P, though GVE-P fibers of CNs III, VII, IX distribute their fibers via this nerve.

Question 15

CN VI

Answer 15

Abducens: GSE

1. innervation of extra-ocular muscle: lateral rectus
2. turns the eye laterally - named for ability to abduct the eye

Question 16

CN VII

Answer 16

Facial: SVE, GSA, SVA, GVA, GVE-P (all but SSA)

1. SVE: motor innervation to skeletal muscles of second arch origin: muscles of facial expression, sylohyoid, posterior belly digastric muscle, stapedius
2. GSA: sensory to a portion of the skin of the external ear and external auditory meatus
3. SVA: taste to anterior 2/3 of tongue via chorda tympani
4. GVA: sensory to uppermost portion of pharynx
5. GVE-P: PS to lacrimal gland, nasal, palatal, oral and pharyngeal mucous glands via greater petrosal n. and pterygopalatine ganglion; to the submandiular and subliqual salivary glands via chorda tympani and submandibular ganglion

Question 17

CN VIII

Answer 17

Vestibulocochlear: SSA, SSE

1. SSA: affarent fibers from organ of Corti (sense of hearing). Afferent fibers from semicircular canals, utricle and saccule of internal ear relative to sense of equilibrium
2. SSE: motor fibers related to modifying auditory input.

Question 18

CN IX

Answer 18

Glossopharyngeal: SVE, GSA, SVA, GVA, GVE-P

1. SVE: motor innervation of arch three: stylopharyngeus
2. GSA: sensory to portion of external ear
3. SVA: taste from posterior third of tongue
4. GVA: sensory to epithelium of endodermal origin which lines the majority of pharynx, middle ear, internal tympanic membrane, tonsils, posterior third of tongue, parotid gland, carotid sinus.
5. GVE-P: secretory fibers to the parotid salivary gland via the lesser petrosal n. and otic ganglion

Question 19

CN X

Answer 19

Vagus: SVE, GSA, SVA, GVA, GVE-P

1. SVE: motor innervation to skeletal muscles or arches 4 and 6: muscles of pharynx, palate, larynx and upper portion of esophagus
2. GSA: Cutaneous innervation of skin of external ear, external auditory meatus, external TM and dura mater of posterior cranial fossa
3. SVA: taste from epiglottic surface of tongue in area of epiglottic valleculae
4. GVA: sensory of tongue, larynx, resp system, heart, gut tube, transverse colon and liver, spleen kidney and gonads
5. GVE-P: PS of mucous glands of larynx, smooth m. glands of gut tube, distal third of transverse colon, resp. system and cardiac.

Question 20

CN XI

Answer 20

Spinal Accessory: GSE

- motor innervation to sternocleidomastoid and trapezius m.

Question 21

CN XII

Answer 21

Hypoglossal: GSE

- motor innervation to muscles of tongue: styloglossus, genioglossus, hyoglossus, and intrinsic muscles of tongue