CRANIAL NERVES

INTRODUCTION

–  12 pairs of cranial nerves

 

 

 

 

–  Table 15.6 summarizes all nerves
-- Table 15.7 lists each nerve in detail

CN I: OLFACTORY:
sensory axons only


–  function:  smell (olfaction)

– olfactory nerves synapse in olfactory bulb

 

–  olfactory bulbs connect to olfactory tracts

–  test for nerve damage: test smell

 

 

CN II: OPTIC:
–  sensory axons only


–  function: vision

 


–  optic chiasm

 

 

–  optic tracts

 

–  test for nerve damage:

 

 

CN III: OCULOMOTOR

- somatic motor and parasympathetic motor axons

–  functions:

1. somatic motor:  supplies 4 eye muscles (superior rectus, inferior rectus, medial rectus, inferior oblique) and a muscle in the upper eyelid (levator palpebrae superioris)


2.  parasympathetic motor: supplies iris, will help constrict pupil

 


–  test for nerve damage:

1.  does pupil constrict?

 

 


2.  does the upper eyelid droop?

 

 


3.  Does person have diplopia?

 

 

CN IV: TROCHLEAR:
–  somatic motor axons


–  function:  supplies superior oblique
–  test for nerve damage: diplopia?

 

 

CN V: TRIGEMINAL:
– somatic motor and sensory axons


–  functions:

1.  motor:  muscles of mastication
2.  sensory:  anterior part of scalp, entire face, nasal cavity, oral cavity, teeth

 

 

 


–  test for nerve damage:


1.

 

2.

 


CN VI: ABDUCENS:
–  somatic motor axons
–  function: supplies lateral rectus
–  test for nerve damage:

 

 

 

SO - NOW YOU CAN REVIEW THE EYE MUSCLES MEMORY MATRIX

 

 

CN VII: FACIAL:
– somatic motor, special sensory, and parasympathetic motor axons

 


–  functions:


1.  somatic motor: muscles of facial expression
2.  sensory: TASTE to anterior 2/3 of tongue

 


3.  parasympathetic motor: increases secretion of lacrimal glands, most salivary glands

 



–  test for nerve damage:

 

 

 

 

 

CN VIII: VESTIBULOCOCHLEAR:
–  contains sensory axons only!

 

 


–  functions: hearing and equilibrium


–  test for nerve damage:

1.  test for hearing loss/deafness
2.  is person experiencing vertigo, lack of balance, dizziness, nausea/vomiting?



CN IX: GLOSSOPHARYNGEAL:
–  contains somatic motor, general & special sensory, and parasympathetic motor axons!


–  functions:

1.  somatic motor:  supplies one pharynx (throat) muscle
2.  general sensory: touch and TASTE sensation of post 1/3 of tongue
3.  parasympathetic motor:  increases secretion to parotid gland


–  test for nerve damage:

 

 

 

CN X: VAGUS:


–  contains primarily somatic motor and parasympathetic motor axons


–  functions:

1.  somatic motor: supplies most pharynx (swallowing) muscles and larynx (voice box) muscles

 

parasympathetic motor: supply muscle in the heart, lungs, most abdominal organs

 

–  test for nerve damage:


1.  does person have difficulty swallowing?
2.  does person have a hoarse voice, permanent loss of voice

 

CN XI: ACCESSORY:
–  contains somatic motor axons

 


–  functions:  innervates trapezius and sternocleidomastoid         

 
–  test for nerve damage:

     

 

 

 

CN XII: HYPOGLOSSAL:
–  somatic motor axons
–  functions:  supplies intrinsic tongue muscles and most extrinsic tongue muscles

–  test for nerve damage:

 

 

 

 


Before you get a cavity filled in your tooth, you HOPE that the dentist will anesthetize (numb) a branch of this nerve:

a.   CN IV (trochlear)

b.   CN V (trigeminal)

c.   CN VII (facial)

d.   CN IX (glossopharyngeal)

e.   CN X (vagus)

 

 

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