cranial nerve review 12-9

what are exceptions to the sympathetic fibers that do travel with cranial nerves

Exceptions are the sympathetic fibers found in the deep petrosal nerve, nasociliary, short ciliary & long ciliary nerves

the chorda tympani also contain what type of fibers besides parasympathetic

Remember that the chorda tympani nerve also conveys taste fibers (SA, CN VII, red) from the anterior two‐thirds of the tongue.

what other components besides sympathetic does the greater petrosal nerve carry

Remember that the greater petrosal nerve is also carrying taste information [SA] from the soft palate

what are sympathetic targets in the head?

Sympathetic targets in the head and neck include sweat glands, arrector pili smooth muscle, vascular smooth muscle and two smooth muscles of the eye. These are the superior tarsal muscle and the dilator pupillae muscle.

describe sympathetics innervation to the submandibular and sublingual glands

Sympathetics to these two salivary glands are distributed via the carotid peri‐arterial plexus along the lingual and facial arteries

GSA and GVA sensory cell bodies of cranial nerve 9 are located where

The GSA and GVA sensory cell bodies are located in the inferior sensory ganglion of IX.

describe postganglionic sympathetic distribution of deep petrosal nerve

These postganglionic sympathetic fibers distribute to the lacrimal gland and minor glands in the nasal and oral cavities and the soft palate by hitchhiking along branches of the trigeminal nerve. The remaining postganglionic sympathetic fibers (except those to the smooth muscles of the orbit, ) reach their target primarily by way of the carotid periarterial plexus.

what are the two peripheral sensory ganglia cranial nerve 9 is associated with and which components does it house

associated with two peripheral sensory ganglia, superior and inferior, which house GSA, GVA, and SA sensory cell bodies.

SA (taste) sensory fibers to anterior 2/3 of tongue and soft palate are conveyed via which nerves?

chorda tympani/greater petrosal nerves.

what is the parasympathetic terminal motor ganglia in the head associated with cranial nerve 3

ciliary ganglion

which cranial nerves are pure motor cranial nerves

cranial nerve 3, 4, 6, 11, 12

taste buds on the soft palate are innervated by which nerve

greater petrosal nerve of 7

overview of parasympathetics to the head: CN 10

preganglionic cell body location is in medulla. Terminal ganglion in terminal ganglia in wall of viscera, including structures of the neck, foregut and midgut. Target is smooth muscle and glands of thorax, foregut and midgut.

what is the parasympathetic terminal motor ganglia in the head associated with cranial nerve 7

submandibular ganglion, pterygopalatine ganglion

where does chorda tympani exit the skull

the chorda tympani exits the skull via the petrotympanic fissure.

The glossopharyngeal nerve leaves the brainstem and exits the posterior cranial fossa via

the jugular foramen

Where does GSA fibers of cranial nerve 7 exit

There are also GSA sensory fibers to portions of external ear. These sensory cell bodies are found in the geniculate ganglion and the GSA fibers exit via the stylomastoid foramen along with the BE motor fibers.

cranial nerve 9 gives GSA fibers to?

There are also GSA sensory fibers to the posterior 1/3 tongue, palatine tonsils, oropharynx, mucosa of middle ear and auditory tube and GVA sensory fibers to the carotid body and sinus.

functions of mixed cranial nerve 7

- BE to muscles of facial expression, stapedius, stylohyoid, posterior digastric [2nd pharyngeal arch]. - GVE parasympathetic to lacrimal, submandibular and sublingual glands, and mucous glands of oral cavity, nasal cavity, and palate. - GSA to portion of external ear. - SA (taste) to anterior 2/3 of tongue and soft palate

function of mixed cranial nerve 10 vagus

- BE to muscles of the 4th and 6th pharyngeal arches including muscles of larynx, pharynx [except for stylopharyngeus], and palate [except for tensor veli palatini]. - GVE parasympathetic to smooth muscles and mucous glands of the trachea and esophagus. - GSA to skin of posterior ear and external acoustic meatus, lower third of the pharyngeal mucosa and esophagus, laryngeal mucosa, and root of tongue. - GVA to carotid body. - SA taste to base of tongue and epiglottis.

functions of mixed cranial nerve 9

- BE to stylopharyngeus form 3rd pharyngeal arch. - GVE parasympathetic to parotid gland. - GSA to posterior tongue, palatine tonsils, oropharynx, mucosa of middle ear and auditory tube. - GVA to carotid body and sinus. - SA taste to posterior 1/3 of tongue.

what components do short ciliary nerve contain

- GSA sensory branches of V1. - parasympathetic postganglionic fibers. - sympathetic fibers.

what components do long ciliary nerve contain

- GSA sensory branches of V1. - sympathetic fibers.

overview of parasympathetics to the head: CN 9

- preganglionic cell body location: medulla. - preganglionic fiber: tympanic nerve; lesser petrosal nerve. - terminal ganglion: otic ganglion. - course of post ganglionic fibers: auriculotemporal nerve from 5. - target: parotid gland.

overview of parasympathetics to the head: CN 3

- preganglionic cell body location: midbrain. - preganglionic fiber: 3. - terminal ganglion: ciliary ganglion. - course of post ganglionic fibers: ciliary nerves from CN 5. - target: eyeball = ciliary muscle and constrictor muscle of pupil.

overview of parasympathetics to head: CN 7 submandibular

- preganglionic cell body location: pons. - preganglionic fiber: chorda tympani nerve. - terminal ganglion: submandibular ganglion. - course of post ganglionic fibers: lingual nerve from CN 5. - target:

overview of parasympathetics to head: CN 7 pterygopalatine

- preganglionic cell body location: pons. - preganglionic fiber: greater petrosal nerve. - terminal ganglion: pterygopalatine ganglion. - course of post ganglionic fibers: zygomatic and lacrimal nerves from CN 5. - target: lacrimal gland.

where does BE motor fibers to muscles of 2nd arch exit

BE motor fibers to muscles of 2nd arch exit via the stylomastoid foramen and travel through the parotid gland. The BE motor cell bodies are located in the brainstem motor nucleus of VII

recurrent or inferior laryngeal nerve of cranial nerve 10

BE to all other muscles of the vocal folds except cricothyroid, GSA to mucosal lining of the larynx below the vocal folds

external branch of the superior laryngeal nerve of cranial nerve 10

BE to cricothyroid muscle

pharyngeal branch of CN 10

BE to palatoglossus, all muscles of the pharynx [except stylopharyngeus] and all muscles of the soft palate [except tensor veli palatini]

describe pure sensory component of CN 1

CN I is responsible for our sense of smell. It exits the skull via the cribriform foramina in the anterior cranial fossa. Note that the SA cell bodies are not organized into a peripheral sensory ganglia, rather they are diffusely distributed along the olfactory epithelium.

describe pure sensory component of CN 2

CN II is responsible for our sense of sight. It exits the skull via the optic canal in the middle cranial fossa. Note that the SA cell bodies are not organized into a peripheral sensory ganglia, rather they are diffusely distributed in the retina.

describe the pure motor component of cranial nerve 4

CN IV exits the skull via the superior orbital fissure in the middle cranial fossa and is responsible for the innervation of the superior oblique muscle. Lesion of the trochlear nerve would result in weakness in depression, adduction and intorsion of the eyeball. To test the integrity of this nerve, you would ask the patient to look medially and down.

where is the BE motor cell bodies of cranial nerve 9 located

CN IX provides BE innervation to the single muscle of the 3rd pharyngeal arch. The BE motor cell bodies are located in the brainstem motor nucleus of IX and fibers reach the stylopharyngeus muscle via the nerve to the stylopharyngeus on the posterior aspect of the pharynx

describe the pure motor component of cranial nerve 6

CN VI exits the skull via the superior orbital fissure in the middle cranial fossa and is responsible for the innervation of the lateral rectus muscle. Lesion of the abducent nerve would result in inability to abduct the eyeball. To test the integrity of this nerve, you would ask the patient to look laterally. Remember the LR6SO4 mnemonic.

describe pure sensory component of CN 8

CN VIII is responsible for audition and equilibrium. It exits the skull via the internal acoustic meatus in the posterior cranial fossa. Note that the SA cell bodies are found in the spiral and vestibular ganglia.

describe the pure motor component of cranial nerve 11

CN XI exits the skull via the jugular foramen. It travels deep to the SCM, providing its innervation, and then crosses the floor of the posterior triangle of the neck to form the subtrapezial nerve plexus along with fibers from C3 and C4 ventral rami deep to the trapezius muscle. Remember that the accessory nerve is not a true cranial nerve as it takes its origin from the upper cervical spinal cord segments and enters the cranial cavity via the foramen magnum.

describe the pure motor component of cranial nerve 12

CN XII exits the skull via the hypoglossal canal. It passes parallel and inferior to the tendon of the digastric muscle and enters the submandibular triangle on the external surface of the hyoglossus muscle. It innervates all the intrinsic muscles of the tongue and three of the four extrinsic muscles of the tongue [all except palatoglossus].

what are some clinical tests for lesion of CN 10

Clinical tests would include listening to the patient's speech, evaluation of swallowing, testing the gag reflex,and examination of the uvula by having the patient say "Ahh".

auricular nerve of CN 10

GSA to external ear

Internal branch of the superior laryngeal nerve of CN 10

GSA to mucosal lining of the laryngopharynx down to the vocal folds, GVE parasympathetic to glands of the pharynx, GSA to root of tongue and epiglottis, SA (taste) to root of tongue and epiglottis

meningeal nerve of CN 10

GSA to the dura in the posterior cranial fossa

sinus nerve of CN 10

GVA to carotid body

where are GSE body of cranial nerve 4, 6, 11, and 12 located

IV, VI, XI and XII carry a single functional component, GSE. The GSE cell bodies are found in the brainstem motor nuclei associated with these cranial nerves.

what would you see with loss of cranial nerve 9

Loss of the glossopharyngeal nerve would present clinically as the absence of the gag reflex [sensory IX, motor X], along with a dry mouth due to loss of innervation of the parotid salivary gland. Clinical test for the integrity of CN IX is to stimulate the gag reflex. Absence of the gag reflex can be explained by loss of either IX or X, so further testing would be required. One discriminator would be the presence of absence of dry mouth.

cranial nerve V2 provides innervation to which part of the skin

It provides GSA innervation to the skin of the face over the maxilla, upper teeth and gingiva, maxillary sinus, nasal cavity, part of nasopharynx, and the hard and soft palate.

what part of the skin does cranial nerve V3 mandibular innervates

It provides sensory innervation to the skin of the face over the mandible, parotid capsule, floor of the mouth, and the lower teeth and gingiva. Its major motor branches (BE) are the nerves to the masseter, temporalis, medial pterygoid, lateral pterygoid and mylohyoid. It is responsible for BE innervation to the muscles of the first pharyngeal arch.

what would you see in lesion of cranial nerve 7

Lesion of CN VII would result in facial paralysis on the affected side due to loss of BE motor innervation, loss of taste on the anterior two‐thirds of the tongue [loss of SA sensory innervation] and dry eye/dry mouth due to loss of parasympathetic innervation of the submandibular and sublingual salivary glands. Easy clinical tests for CN VII function are asking the patient to smile or raise their eyebrows.

what would you see with a lesion of cranial nerve 12

Lesion of CN XII would result in paralysis of all tongue muscles on the affected side [with the exception of palatoglossus]. To test nerve function, the patient is asked to stick out their tongue. If the nerve is lesioned, the tongue will deviate to the affected side.

lesion of cranial nerve V2 maxillary would result in what

Lesion of V2 would result in loss of general sensation of the skin over the maxilla and of the maxillary teeth.

what would you see with a lesion of cranial nerve V3 mandibular

Lesion of V3 would result in loss of general sensation of the skin over the mandible, the mandibular teeth, tongue, weakness in chewing and deviation of the jaw to the side of the lesion. The GSA sensory cell bodies of each division are found in the trigeminal ganglion. The BE motor cell bodies of V3 are found in the brainstem motor nucleus of V.

what would you see with a lesion of CN 10

Lesion of the CN X would manifest as difficulty swallowing (or dysphagia) due to loss of innervation of pharnygeal muscles, hoarseness or paralyzation of the vocal fold due to loss of innervation of laryngeal muscles, loss of gag reflex, loss of cough reflex, drooping palate and displacement of the uvula away from the side of the lesion.

what would you see with a lesion of cranial nerve 3

Lesion of the oculomotor nerve can result in several clinical manifestations. Loss of parasympathetic innervation to the sphinchter pupillae muscle will result in a dilated pupil with loss of the light reflex on the affected side. Loss of motor innervation to multiple extraocular muscles results in severe ptosis (levator palpebrae superioris), diplopia, external stabismus (eye moves down and out at rest due to unopposed CN IV and VI), and loss of parallel gaze. The easiest clinical test is the pupillary light test.

what would you see if cranial nerve 11 was damaged

Loss of innervation to the trapezius present as a drooping shoulder on the affected side. Loss of innervation to SCM would present as weakness in flexion and/or rotation of the neck on the affected side. A common clinical test for the integrity of CN XI is to ask the patient to elevate the shoulders against force.

postganglionic parasympathetic fibers of lesser petrosal nerve that distribute to the parotid gland hitchhike on which nerve

Postganglionic fibers distribute to the parotid gland by hitchhiking on the auriculotemporal nerve [another GSA sensory branch of V3, which provides GSA to parotid capsule among other things].

describe the course of postganglionic sympathetic fibers destined for the head

Postganglionic fibers exit the sympathetic chain and form the carotid peri‐arterial plexus which surrounds the internal and external carotid arteries and their branches to reach their targets in the head. Note that most [>95%] of these fibers do not travel with cranial nerves.

important concept of postganglionic parasympathetic fibers

Postganglionic parasympathetic fibers "hitchhike" primarily on named branches of the three divisions of the trigeminal nerve (CN V) to reach their targets in the head.

parasympathetic innervation of the smooth muscles of the eye via the short ciliary nerve of CN 3: postganglionic course

Postganglionic parasympathetic fibers exit the ganglia and hitchhike along the short ciliary nerves [sensory branches of V1, GSA] to reach their targets.

course of postganglionic parasympathetic of chorda tympani

Postganglionic parasympathetic fibers then leave the submandibular ganglion and travel to the submandibular gland or rejoin the lingual nerve to reach the sublingual gland.

which nerve does postganglionic parasympathetic fibers of greater petrosal nerve of 7 travel with

Postganglionic parasympathetic fibers travel with GSA branches of V1 and V2 to reach the lacrimal gland, including the zygomatic nerve [V2, GSA] and lacrimal nerve [V1, GSA]. Other postganglionic parasympathetic fibers distribute with GSA branches of V2 that originate from the ganglion, such as the palatine nerves and nasal branches. These fibers are destined for minor salivary glands on the soft palate and mucous glands in the nasal cavity.

parasympathetic innervation of the parotid gland via the tympanic/lesser petrosal nerve of CN 9 part 1

Preganglionic fibers from CN IX that are destined for the parotid gland exit the skull along with the rest of CN IX via the jugular foramen. These fibers join the tympanic nerve and ascend to the tympanic cavity through a canal in the bone separating the carotid canal and jugular foramen. This is sometimes called the tympanic cannaliculus. Preganglionic parasympathetic fibers continue beyond the middle ear plexus as the lesser petrosal nerve. This is just a name change.

parasympathetic innervation of the smooth muscles of the eye via the short ciliary nerve of CN 3: preganglionic course

Preganglionic parasympathetic fibers from CN III that are destined to innervate these smooth muscles have their cell bodies in the brainstem motor nuclei of CN III. These preganglionic parasympathetic fibers exit the cranial cavity via the superior orbital fissure along with the rest of cranial nerve III. These fibers enter the orbit and reach the ciliary ganglion via the parasympathetic motor root of III. Within the ciliary ganglion, synapses are formed with postganglionic parasympathetic cell bodies.

parasympathetic innervation of lacrimal gland via greater petrosal nerve of cranial nerve 7 part 1

Preganglionic parasympathetic fibers from CN VII that are destined to innervate the lacrimal gland have their cell bodies in the brainstem and preganglionic fibers enter the internal acoustic meatus along with the rest of cranial nerve VII. These fibers leave the facial canal as the greater petrosal nerve via the hiatus of the greater petrosal nerve and enter the middle cranial fossa. The greater petrosal nerve runs along the floor of the middle cranial cavity in the groove of the greater petrosal nerve. It drops through foramen lacerum to reach the pterygoid canal of the sphenoid bone.

describe course of preganglionic sympathetic fibers destined for the head

Preganglionic sympathetic fibers destined for the head arise from spinal cord segments T1‐T2. Pre‐ ganglionic cell bodies are located in the spinal cord gray matter (lateral horn) of these segments. The preganglionic axons exit the spinal cord via the T1 & T2 spinal nerves to reach the sympathetic trunk. These fibers (shown in dark blue) then ascend in the sympathetic trunk to reach the superior cervical chain ganglion where they synapse with the postganglionic neurons.

other notes on short ciliary nerve

Remember that the short ciliary nerves are also carrying postganglionic sympathetic fibers and GSA sensory fibers. These sympathetic fibers as well as others traveling in the long ciliary nerves are destined to innervate two other smooth muscles of the eye, the dilator pupillae and the superior tarsal muscle.

where are the cell bodies of taste neurons of chorda tympani located

The cell bodies of taste neurons are located in the geniculate ganglion in the genu of the facial canal.

describe the course of the chorda tympani nerve of CN 7 that give parasympathetic innervation to the submandibular and sublingual gland part 2

The chorda tympani nerve joins the lingual nerve [GSA (green) sensory branch of V3] high in the infratemporal fossa, and hitchhikes along with that nerve to the submandibular ganglion, where synapses are formed with postganglionic parasympathetic cell bodies.

The chorda tympani nerve of CN VII , carries which component?

The chorda tympani nerve of CN VII , carries preganglionic parasympathetic fibers [and also taste fibers].

describe the deep petrosal nerve

The deep petrosal nerve consists of postganglionic sympathetic fibers coming off the internal carotid artery; it joins with the greater petrosal nerve [ which is branch of CN VII, GVE/SA] to form the nerve of the pterygoid canal [ contain sympathetic & parasympathetic GVE, SA].

where does the facial nerve leaves the brainstem

The facial nerve leaves the brainstem and enters the temporal bone via the internal acoustic meatus along with CN VIII.

what is the name of the sensory ganglion of facial nerve

The geniculate ganglion is the sensory ganglion of the facial nerve; it is located at the abrupt bend (genu) taken by the nerve as it turns from the meatus into the facial canal. It houses GSA and SA sensory cell bodies.

parasympathetic innervation of lacrimal gland via greater petrosal nerve of cranial nerve 7 part 2

The greater petrosal nerve joins with the deep petrosal nerve [postganglionic sympathetic fibers] to form the nerve of the pterygoid canal en route to the pterygopalatine ganglion located in the PP fossa where synapses are formed with postganglionic parasympathetic cell bodies.

parasympathetic innervation of the parotid gland via the tympanic/lesser petrosal nerve of CN 9 part 2

The lesser petrosal nerve passes forward through the petrous part of the temporal bone and emerges through the hiatus of the lesser petrosal nerve onto the floor of middle cranial cavity. It crosses floor of the middle cranial fossa in the groove of the lesser petrosal nerve, then exits the skull via foramen ovale (with V3) to reach the otic ganglion in the infratemporal fossa where synapses are formed with postganglionic parasympathetic cell bodies.

describe the distribution of cranial nerve 10

The vagus nerve exits the cranial cavity via the jugular foramen. It carries GSA, GVA, SA, BE and GVE fibers via the following named branches. Sensory cell bodies are located in the superior or inferior sensory ganglia of X. BE motor cell bodies are found in the brainstem motor nucleus of X.

describe the pure motor component of cranial nerve 3

The oculomotor nerve is still a pure motor cranial nerve, but it carries both GSE and GVE fibers. It exits the cranial cavity via the superior orbital fissure in the middle cranial fossa. Once in the orbit, it splits into superior and inferior branches. The superior branch of CN III innervates the levator palpebrae superioris and the superior rectus muscles. The inferior branch of CN III innervates the medial rectus, inferior rectus and inferior oblique muscles.

describe the course of the chorda tympani nerve of CN 7 that give parasympathetic innervation to the submandibular and sublingual gland part 1

The preganglionic cell bodies are located in the brainstem motor nuclei of CN VII. The preganglionic fibers enter the facial canal, bypassing the geniculate ganglion, before entering a separate canal in the bone which conducts it to the middle ear [tympanic cavity]. The nerve passes over the medial surface of the tympanic membrane, arches across the malleus, and leaves the tympanic cavity near the anterior border of the membrane and exits the skull via the petrotympanic fissure.

describe cranial nerve 7 GSA innervation to portion of external ear

The somatosensory innervation of the outer ear structures is a bit complex; the diagram from Thieme (right) shows that there are some sensory fibers (blue dots) from VII that innervate some of the auricle, skin of the auditory canal, and skin behind the ear.

special note on tympanic nerve of CN 9

The tympanic nerve is also carrying GSA fibers to the middle ear and auditory tube. remember that the GSA cell bodies are contained in inferior sensory ganglion of IX.

describe the components of the mixed cranial nerve V1 opthalmic

V1 [GSA] exits the skull via the superior orbital fissure. It has three main branches, frontal, lacrimal and nasociliary. These branches provide GSA innervation to skin of the face & scalp, lacrimal gland and mucous membranes of the nasal cavity. Lesion of V1 would result in loss of general sensation of the skin on the forehead/scalp.

major branches of cranial nerve V2 maxillary

V2 (GSA) exits the skull via foramen rotundum and enters the PP fossa. Its major branches are the orbital branches, zygomatic nerve, infraorbital nerve, posterior superior alveolar nerve, greater & lesser palatine nerves, nasopalatine nerve, lateral nasal branches and pharyngeal nerve.

describe the components of the mixed cranial nerve V3 mandibular

V3 (GSA/BE) exits the skull via foramen ovale and enters the IT fossa. Its major sensory branches are the auriculotemporal nerve, inferior alveolar nerve, lingual nerve and buccal sensory nerve.

what is the parasympathetic terminal motor ganglia int he head associated with cranial nerve 9

otic ganglion