Lecture 19 (4/14) Flashcards
PNS
PNS (Overview)
Lies outside of the skull and vertebral columns
The means by which nervous impulses are conveyed to and from the CNS
Made up of two functional systems:
Autonomic Nervous System
Somatic Nervous System
Somatic Nervous System
One of two functional systems of the PNS
Has two main components:
Spinal Nerves
Cranial Nerves
Cranial Nerves
There are 12 CNs
Most synapse with the CNS in the brainstem
Each of the CNs serves motor info, sensory info, or both
I - Olfactory II - Optic III - Oculomotor IV - Trochlear V - Trigeminal VI - Abducens VII - Facial VIII - Vestibular IX - Glossopharyngeal X - Vagus XI - Spinal Accessory XII - Hypoglossal
Cranial Nerve I
Olfactory
Serves only sensory function
How to test:
The sensation of smell can be tested by having the patient not look at the stimuli or having it wrapped in something and then presenting by asking them to name the smell (onions, peppermint)
Cranial Nerve II
Optic
Serves only sensory function
How to test:
Hold a different object in each hand and have arms spread wide. With the patient looking at the center you move your arms inward until they can see the objects
Determine the integrity of the pupil
Shining a light into the eye - if the pupil is ok it will constrict immediately
Cranial Nerve III
Oculomotor
Serves only motor function - eye movement
Injury to CN III results:
- in drooping of the eyelid, known as ptosis
- -caused by paralysis to the muscles that raise the eyelid
Patients often complain of double vision (diplopia)
Ptosis
Drooping of the eyelid
Diplopia
Double vision
Cranial Nerve IV
Trochlear
Serves only motor function - eye movement
Injury causes upward deflection of the effected eye during forward gaze - patient may also experience diplopia
Cranial Nerve V
Trigeminal
Serves both sensory and motor
Sensory branch has 3 division
Opthalamic
Maxillary
Mandibular
Motor branch
Innervates muscles of mastication
Can be tested by asking the patient to open and close the jaw against resistance
If V is injured patient may not be able to chew
Opthalamic Division
Division of the sensory branch of the Trigeminal nerve
Provides sensation to the eye, upper eyelid, the bridge of the nose, and the anterior scalp
Maxillary Division
Division of the sensory branch of the Trigeminal nerve
Provides sensation to the cheeks, the nose, upper teeth and lip, the hard palate, and the nasopharynx
Mandibular Division
Divison of the sensory branch of the Trigeminal nerve
Provides sensation to the skin of the lower jaw, outer ear, lower teeth and gums, the floor of the mouth, the inside surfaces of the cheek
Corneal Reflex
A test in which a cotton swab is dragged against the eyeball to check for the blinking reflex
Cranial Nerve VI
Abducens
Serves only motor function - eye movement
Injury causes inward deflection of the effected eye
- patient experiences diplopia when looking toward the side of the effected eye
- patient may also experience nystagmus
Nystagmus
Rhythmic oscillation of the eye
Cranial Nerve VII
Facial
Serves both sensory and motor
Motor:
Involved in the motor movement of the muscles of the face for facial expression
If damaged the muscles of facial expression may be paralyzed
- Cant close the eyelid tightly, wrinkle the forehead, or pucker the lips
- in some cases the facial muscles of one side can be paralyzed
Sensory:
Involved in taste, specifically involved in the anterior ⅔ of the tongue
Cranial Nerve VIII
Vestibular
Serves only sensory function - involved in hearing
To test:
Cause use different tasks, such as whispering into the ear of the patient or using a tuning fork or a ticking clock
Cranial Nerve IX
Glossopharyngeal
Serves both sensory and motor
Motor:
Swallowing
Sensory:
Taste: posterior ⅓ of tongue, visceral sensation from palate and oral pharynx
IX and X can be tested together by testing the sensitivity of the posterior wall of the pharynx with a tongue depressor
Cranial Nerve X
Vagus
Serves both sensory and motor
Phonation and swallowing - gag reflex
Cranial Nerve XI
Spinal Accessory
Serves only motor function - Head movement and shoulder elevation
Injury causes:
Damaged side of the body to droop
Can test by asking the patient to raise his shoulders against resistance
Cranial Nerve XII
Hypoglossal
Serves only motor function - tongue movement
Injury to XII can cause the patient’s tongue to deviate toward the side of injury (ipsilateral)
Can test by evaluating the patient’s ability to protrude the tongue and seeing if they can move it from one side or the other. This can also be done against resistance
