Cranial Nerves Flashcards
CN I
Name: Olfactory
Function: Smell
Origin: Hypothalamus to brainstem (temporal love cortex)
I: olfactory bulb (cribiform plate)
SD: Loss of smell
Testing: Have patient close one nostril and waft familiar smell like coffee or lemon.
CN II
Name: Optic
Function: Vision
Origin: Thalamus to occipital lobe
I: retina
SD: Cortical blindness (patient cannot interpret what is seen.)
Testing: bring eyes to midline, peripheral vision
CN III
Name: Oculomotor
Function: Moves eyeball, pupil and eyelid (controls iris and lens)
Origin: Pons (Superior Colliculus)
I: 4 eye muscles
SD: Inability to move eyes in conjugate or convergent direction, ptosis
Testing: H shape, look for nystagmus, Light in eye to test for equal and reactive pupils,
CN IV
Name: Trochlear Function: Superior oblique muscle Origin: Pons (Inferior Colliculus) I: superior oblique muscle SD: Inability to look down or to the side, diplopia. Testing: H shape
CN VII
Name: Facial
Function: Sensory and motor to muscles of facial expression, wrinkling forehead, closing eyes tightly, pursing and tensing lips. Larynx, salivary glands, taste
Origin: Pons
SD: Mask-like facial features, Bell’s palsy, drooling, difficulty keeping food in mouth, nasolabial fold flattened,
Unilateral: facial asymmetry during movement
Bilateral: decreased ability to retract, puff or purse.
Testing: Facial expressions, closing eyes tight, don’t let clinician open them, raise eyebrows, puff cheeks against resistance, show teeth, sniff
CN V
Name: Trigeminal
Opthalmic branch is sensory to lacrimal gland, eyelid, cornea, iris, mucous memrane of nasal cavity perinasal sinuese, skin to superior facial region and upper scalp.
Maxillary branch: sensory to midface, dura of lower eyelid, mucous membrane, upper mouth nose and pharynx, upper jaw,teeth and palate.
Mandibular branch (largest) both sensory and motor. Lower teeth and gums, mastication, skin of ear, temporal regions and skin of jaw, mucous membrane of anterior 2/3 of tongue.
Origin: Pons
SD: Unilateral: jaw deviation, Bilateral: inability to close jaw Numbness, difficulty chewing, loss of coroneal reflex, trigeminal neuralgia, tic douloureux, increased sensitivity to sound
Testing: test all three branches, drag fingers on forehead, cheekbones and jaw. Open and close and move side to side against resistance. Test coroneal reflex with thread on eye.
CN VI
Name: Abducens Function: Abducts eyes, lateral eye movement Origin: Pons I: lateral rectus muscle SD: Eye pulls toward nasal side Testing: H Shape
CN VIII
Name: Vestibulocochlear
Function: Hearing and balance
Origin: Pons
I: inner ear
SD: Conductive hearing loss and loss of balance
Testing: Whisper test and bone conduction with tuning fork and stand from chair, walk, turn and walk back
CN IX
Name: Glossopharyngeal
Function: Motor to Stylopharyngeus muscle (elevation of pharynx and larynx)
Sensory to taste for posterior 1/3 of tongue, gag reflex
Origin: Medulla
SD: No gag reflex
Testing: Elicit pharyngeal gag reflex, look for rising palate
CN X
Name: Vagus
Function: Motor to muscles of soft palate, pharynx and larynx
Sensory to mucous membranes of epiglottis, base of tongue and larynx. External ear,
Origin: Medulla
SD: Changes in voice and resonance, nasal regurgitation, breathiness, hoarseness
Unilateral: soft palate pulls to weak side on phonation
Bilateral: minimal palatal movement
Testing: Laryngoscopy
CN XI
Name: Spinal Accessory Function: Shoulder and head movement Origin: Medulla (spinal cord) I: trapezius and sternocleidomastoid SD: Testing: Shrug shoulders against resistance, turn head against resistance.
CN XII
Name: Hypoglossal Function: tongue movement Origin: medulla I: tongue muscles SD: irregular movements Testing: Hold tongue out without support look for fasciculation, atrophy or drifting. Push against stick.
Originating in Pons
V, VI, VII, VIII
Originating in Medulla
VIII, IX, X, XI, XII
Originating in Superior Colliculus
CN III
