Cranial Nerves Flashcards
What kind of nerve is CN V? (Trigeminal)
Motor & Sensory
CN V’s primary motor function is…
Chewing
What muscles do CN V innervate?
Muscles to close jaw: masseter, temporalis, medial pterygoid
Muscles to open jaw: lateral pterygoid, ant. belly of digastric, mylohyoid
Tensory veli palatini to close VP/tense velum
Tensory tympani to tense tympanic membrane
What is sensory purpose of CN V?
Pain & tactile from forehead, eyes, nose, lips, maxilla, mandible, teeth, cheeks, gums, cheeks, palate and max. sinus & anterior 2/3 of tongue
Other CN V functions (aside from chewing)
- mastication
- articulation
- hyolaryngeal elevation
- tensing/closing of of soft palate
- sensation to face, teeth, gums and ant 2/3 of tongue
How to test CN V
- Palpate Masseter muscles as patient bites down
- Can patient close jaw against mod. resistance?
- Can patient open jaw freely against resistance?
- Check to see if jaw deviates towards side of weak lateral pterygoid
- Can patient lateralize jaw against resistance? (weakness is expressed as difficulty moving in opposite direction)
No significant motor deficits due to innervation
Unilateral UMN damage
Mandible deviates to the side of paralysis/paresis during opening; muscle hypotonia and atrophy; impaired hyolaryngeal elevation…
LMN damage
Hypertonia, slow movements, restricted haw opening/closing, reduced hyolaryngeal elevation are signs of…
bilateral UMN damage
Hypotonia, significant impaired jaw opening/closing, and significant impaired hyolaryngeal elevation are signs of…
bilateral LMN damage
CN V sensory testing
-assess light touch on face (3 divisions); check right & left
- ophthalmic branch = stroke above eyebrows
-maxillary branch = stroke upper lip or central cheek; gums or hard/soft palate
- mandibular branch = stroke between lower lip and chin; floor of mouth, lower gums, ant. 2/3 of tongue
What kind of nerve is CN VII? (Facial)
Motor & Sensory
What muscles does CN VII innervate? (motor)
- muscles of facial expression
-platysma, stylohyoid, stapedius, and post. belly of digastric - also lacrimal, submandibular, and sublingual glands (visceral motor)
Sensory aspects of CN VII?
-Taste for ant. 2/3 of tongue, floor of mouth, and soft/hard palates
- tactile of external ear and auditory meatus
What are the functions of CN VII?
Movements of facial expression, supporting hyolaryngeal elevation, saliva and tear production, and tase of ant. 2/3 of tongue
Motor testing of CN VII
- Facial symmetry: look for flattening of nasolabial fold, lower face droop, smooth forehead
- Motor Function of upper and lower face: can patient wrinkle forehead, close eyes tightly, spread lips (smile), keep lips compressed against resistance (pucker), or keep cheeks puffed to resistance
Unilateral UMN of CN VII looks like…
Contralateral lower face weakness. No upper face weakness as it is bilaterally innervated.
Bilateral UMN damage looks like…
spastic paralysis of whole face.
Sensory testing of CN VII
test taste on each side of tongue = salty, sour, bitter, sweet
What kind of nerve is CN IX (glossopharyngeal)?
Motor and Sensory
What muscle does CN IX innervate?
Stylopharyngeus muscle (helps elevate larynx and pharynx)
Sensory innervation of CN IX…
General sensation for post 1/3 of the tongue, soft palate, fauces, tonsils, and adenoids. Also taste of post. 1/3 of the tongue.
CN IX is important to trigger what part of swallow?
Pharyngeal stage
What nerve is responsible for gag reflex (sensory)?
CN IX
* can also test gag reflex to test sensory aspect of this nerve
What is the most complex cranial nerve?
Vagus Nerve (CN X)
What are the branches of CN X?
- Laryngeal branch (recurrent and superior: internal and external)
-Pharyngeal branch
Laryngeal branch: recurrent laryngeal nerve
- innervates all intrinsic laryngeal muscles (except cricothyroid)
- general sensation to true VFs and immediately below VFs
Laryngeal branch: superior laryngeal nerve
internal = sensory info from mucous membranes of epiglottis, base of tongue, aryepiglottal folds, and inner surface of larynx (above true VFs)
external = innervates cricothyroid muscle
Pharyngeal branch
Motor innervation for muscles of pharynx and soft palate
What is the motor function of Vagus nerve?
Voice production, VP closure, and swallowing
What is the sensory function of Vagus nerve?
Sensory innervation to base of tongue which plays big role in triggering pharyngeal phase of swallow; above & below VFs to trigger cough reflex; rest of pharynx to allow detection of flood/liquid residue after swallow
Motor testing of Vagus Nerve
Observe palate at rest – look for asymmetry; observe palatal movement during production of “ah”; test gag reflex; check vocal quality (weakness can result in hypophonia); check glottal coup & voluntary cough (blurred attack?)
Bilateral UMN damage of CN V is characterized by…
a strained-strangled vocal quality & will often result in hypernasality
Unilateral LMN damage of CN V will result in …
ipsilateral signs of palatal weakness or VF paresis/paralysis
CN XI is what kind of nerve? (accessory)
Motor only
CN XI innervates what muscles?
palatal muscles, sternocleidomastoid and trapezius
CN XII is what kind of nerve? (Hypoglossal)
Motor only
What muscles does CN XII innervate?
intrinsic muscles of tongue and 3 extrinsic tongue muscles (genioglossus, hyoglossus, styloglossus)
What are the functions of CN XII?
Articulation, oral stage of swallowing, and innervates 1 muscle of pharyngeal stage (geniohyoid = elevation of larynx during swallow)
Motor testing of CN XII
-observe tongue at rest and look for atrophy, fasciculations and tremor or random movements.
- protrude tongue - look for range of motion and symmetry (tongue will deviate towards weak side)
- push tongue inside cheek against resistance - if patient pushes weakly against left cheek, then weakness is on right side
-rapid alternating tongue movements (side to side)
What muscles does CN VII innervate? (motor)
- muscles of facial expression
-platysma, stylohyoid, stapedius, and post. belly of digastric - also lacrimal, submandibular, and sublingual glands (visceral motor)
Unilateral UMN damage of CN XII results in …
Unilateral LMN damage of CN XII results in…
contralateral weakness
ipsilateral weakness
Bilateral UMN or LMN damage of CN XII…
weakness on both sides
Bilateral UMN damage often presents w/ reduced ROM and slow movements
