Cranial Nerves Pt2 Flashcards
What are the branchial motor/SVE functions of the facial nerve (CN VII)?
To supply the stapedius, stylohyoid, posterior belly of digastric, muscles of facial expression including buccinator, platymsa and occipitalis muscles
What is the visceral motor/GVE function of CN VII?
For stimulation of the lacrimal, submandibular and sublingual glands as well as the mucous membrane to the nose and hard/soft palate
What is the general sensory/GSA function of CN VII?
To supply the skin of the concha of auricle, small area of skin behind the ear, possibly to supplement V3 which supplies the wall of the acoustic meatus and external tympanic membrane
What is the special sensory function of CN VII (facial)?
For taste from the anterior 2/3 of the tongue and hard and soft palates
What are two important branches of the CN VII?
Chorda tympani and greater petrosal nerves
What are conditions caused by damage to CN VII?
Decreased tearing (dry eye) and decreased salivation (dry mouth), loss of taste sensation to anterior 2/3 of tongue and/or facial nerve palsy (sometimes called Bell palsy) characterized by paralyzed facial muscles, eyelid droop, sagging at corner of mouth
Branches of facial nerve (CN VII
A tiny zebra bit my cheek Posterior superior auricular Temporal Buccal Mandibular Cervical branch
What does the facial nerve pass through to innervate muscles of facial expression?
Stylomastoid foramen
Deep petrosal nerve of CN VII is what?
Postganglionic sympathetics
Greater petrosal nerve and chorda tympani of CN VII are what?
Preganglionic parasympathetic
Chorda tympani is also special sense (taste)
Describe visceral (parasympathetic) motor innervation to lacrimal gland
Greater petrosal nerve arises from CN VII at geniculate ganglion and emerges from superior surface of petrous part of temporal bone to enter middle cranial fossa ->
Greater petrosal nerve joins deep petrosal nerve (sympathetic) at foramen lacerum to form nerve of pterygoid canal ->
Nerve of pterygoid canal travels through pterygoid canal and entered pterygopalatine fossa ->
Parasympathetic fibers from nerve of pterygoid canal in pterygopalatine fossa synapse in pterygopalatine ganglion ->
Post synaptic parasympathetic fibers from this ganglion innervate lacrimal gland via zygomatic branch of CN V2 and lacrimal nerve branch
Describe visceral (parasympathetic) motor innervation to submandibular and sublingual glands
Chorda tympani branch arises from CN VII just superior to stylomastoid foramen ->
Crosses tympanic cavity medial to handle of malleus ->
Passes through petrotympanic fissure b/w tympanic and petrous parts of the temporal bone to joint the lingual nerve (CN V3) in infratemporal fossa ->
Parasympathetic fibers of chorda tympani synapse in submandibular ganglion and postsynaptic fibers follow arteries to glands
What is the special sensory function of the CN VIII (vestibulocochlear)?
Auditory info from the cochlea (cochlear) and balance information from the semicircular canals (vestibular)
Where does CN VIII originate?
Vestibular branch: hair cells in the vestibule of the inner ear
Cochlear: cochlea of the inner ear
What is the pathway of CN VIII?
Sensory cell bodies of vestibular branch are located in the vestibular ganglion, while sensory cell bodies of the cochlear branch are located in the spiral ganglion near the cochlea
The vestibular and cochlear branches merge and together enter cranial cavity through internal auditory canal and travel to junction of the pons and the medulla oblongata
What conditions are caused by damage to CN VIII?
Lesions in vestibular branch produce loss of balance, nausea, vomiting and dizziness
Lesions in cochlear branch result in deafness (loss of hearing)
What is the branchial motor/SVE function of CN IX (glossopharyngeal)?
To supply the striated muscle (the stylopharyngeus)
What is the visceral motor/GVE function of CN IX?
To supply otic ganglion which sends fibers to stimulate the parotid gland
What is the visceral sensory/GVA function of CN IX (glossopharyngeal)?
Carries sensation (subconscious) from the carotid body and from the carotid sinus
What is the general sensory/GSA function of CN IX?
Provides general sensation from the posterior 1/3 of the tongue, the skin of the external ear, and the internal surface of the TM
What is the origin of CN IX?
Sensory fibers originate on taste buds and mucosa of posterior 1/3 of the tongue as well as the carotid bodies
Motor fibers originate in nuclei in the medulla oblongata
What is the pathway of CN IX?
Sensory fibers travel from posterior 1/3 of tongue and carotid bodies along nerve through the inferior or superior ganglion into the jugular foramen and travels to pons
Somatic motor fibers leave cranium via jugular foramen and travel to stylopharyngeus while sensory fibers go to posterior 1/3 of tongue and carotid bodies
Parasympathetic motor fibers travel to otic ganglion and then to parotid gland
What conditions are caused by damage to CN IX?
Reduced salivary secretion (dry mouth) loss of taste sensation to posterior 1/3 of tongue
Potentially loss of control of BP
Describe the visceral (parasympathetic) motor innervation to the parotid gland
Tympanic nerve arises from CN IX and emerges with it from jugular foramen —> tympanic nerve enters middle ear via the tympanic canalilculus in petrous part of temporal bone —> tympanic nerve forms tympanic plexus on promontory of middle ear —> lesser petrosal nerve arises as a branch of tympanic plexus —> less petrosal N penetrates roof of tympanic cavity (tegmen tympani) to enter middle cranial fossa —> LPN nerves cranium through foramen ovale —> parasympathetic fibers synapse in otic ganglion —> postsynaptic fibers pass to parotid gland via branches of CN V3
What are the branchial motor/SVE function of the vagus nerve (CN X)?
To striated muscles of the pharynx, tongue (palatoglossus) and larynx (except stylopharyngeus)
What are the visceral motor/GVE functions of the vagus nerve?
To smooth muscle and glands of the pharynx, larynx and thoracic and abdominal viscera
What are the visceral sensory functions of the vagus nerve?
From the larynx, trachea, esophagus, and thoracic and abdominal viscera, stretch receptors in the walls of the aortic arch, chemoreceptors in the aortic bodies adjacent to the arch
What is the general sensory/GSA function of the vagus nerve (CN X)?
From the skin of the back of the ear and in external acoustic meatus, part of the external surface of the tympanic membrane and pharynx
What conditions are caused by damage to the vagus nerve?
Paralysis leads to a variety of larynx problems including hoarseness, monotone, or complete loss of voice
Other lesions may cause difficulty or impaired GI system mobility
What is the branchial motor/SVE function of the accessory nerve (CN XI)?
To supply sternocleidomastoid and trapezius
What conditions are associated with damage to the accessory nerve?
Paralysis of trapezius and sternocleidomastoid resulting in difficulty in elevating shoulder (trapezius function) or turning head to opposite side (SCM fxn)
Where does the accessory nerve originate?
Cranial root: motor nucleus in medulla oblongata
Spinal root: motor nuclei in spinal cord
What is the pathway of CN XI?
Spinal root travels superiorly to enter skull through foramen magnum
There cranial and spinal roots merge and leave the skull via jugular foramen
Spinal root travels to SCM and trapezius
What is the somatic motor/GSE function of CN XII (hypoglossal)?
To supply all intrinsic and extrinsic muscles of the tongue except palatoglossus
What is the origin of CN XII?
Hypoglossal nucleus in medulla oblongata
What is the pathway of CN XII?
Leaves cranium via hypoglossal canal
Travels inferior to mandible and to inferior surface of the tongue
What conditions are caused by damage to CN XII?
Swallowing and speech difficulties due to impaired tongue movement
If a single hypoglossal nerve (either L or R) is paralyzed a protruded (stuck out) tongue deviates to the side of the damaged nerve
