cranial nerves

The sensory designation ends in ________________. The motor designation ends in ______________.

"A" (e.g. GSA, GVA, or SA) "E" (e.g. GSE, GVE, or BE)

which nerves have parasympathetic components

(III, VII, IX, and X)

you can add classifications using six rules: 1. All cranial nerves that are purely sensory have "S" by their #

(Some [CN I] Say [CN II] and Says [CN VIII]) and have ONLY an SA classification; no other nerves have ONLY an SA classification.

cranial nerve 1 Roman numeral • Name • Classification and function • Foramen (or foramina) that they pass through to exit the skull

CN I olfactory sensory classification: SA foramen: foramina of cribriform plate

cranial nerve 2 Roman numeral • Name • Classification and function • Foramen (or foramina) that they pass through to exit the skull

CN II optic sensory classification: SA foramen: optic canal

cranial nerve 3 Roman numeral • Name • Classification and function • Foramen (or foramina) that they pass through to exit the skull

CN III oculomotor motor classification: GSE, GVE foramen: superior orbital fissure

cranial nerve 4 Roman numeral • Name • Classification and function • Foramen (or foramina) that they pass through to exit the skull

CN IV trochlear motor classification: GSE foramen: superior orbital fissure

what is the importance of the cavernous sinus

Cranial nerves III, IV, VI and two branches of the trigeminal nerve (V1 and V2) pass through the cavernous venous sinus to reach their targets. Think again about the implications of an infection in the cavernous venous sinus or swelling of the pituitary gland or internal carotid artery. Which nerves would be affected and how would these deficits present themselves? again CNIII does eye muscles (5/7 CNIV does eye muscle(6/7) CNVI does eye muscle (7/7) V1 and V2 of CNV innervate what's above the upper lip(ophthalmic and maxillary)

what is the classification of CN VII

GSA, GVE, BE, SA

6. That the glossopharyngeal and vagus nerves also have

GVA components (these are the only two cranial nerves with GVA components). 9,10

CN IX SA innervation

Notice that the glossopharyngeal nerve (CN IX) receives both taste (SA) and sensation(touch) (GSA) from the posterior 1/3rd of the tongue.

what CNs innervates the carotid body and sinus

Remember that the glossopharyngeal nerve (CN IX) and vagus (x) also innervates (GVA) the carotid body and sinus.

Some Say Money Matters But My Brother Says Big Brains Matter More

S I (SA) S II (SA) M III (GSE)(GVE) P M IV (GSE) B V (BE)(GSA) M VI (GSE) B VII (BE)(GSA)(GVE)(SA) P S VIII (SA) B IX (BE)(GSA)(GVE)(SA)(GVA) P B X (BE)(GSA)(GVE)(SA)(GVA) P M XI (GSE) M XII (GSE)

5. Lastly, remember that the facial, glossopharyngeal, and vagus nerves have a _________________ components

SA 7,9,10

CN X BE innervation

The BE innervation from the vagus nerve is coming from the pharyngeal nerve branch and the external branch of the superior laryngeal nerve. The pharyngeal nerve provides BE innervation to ALL muscles of the pharynx except the stylopharyngeus (which is innervated by the glossopharyngeal nerve). The external branch is BE to the cricothyroid ONLY; ALL of the other muscles of the larynx receive BE innervation from the recurrent laryngeal nerve

CN XI

The accessory nerve (CN XI) originates from multiple smaller branches in the brain stem that merge and pass through the foramen magnum to enter the skull and then leave the cranial cavity via the jugular foramen. The accessory nerve (CN XI) provides GSE innervation to two muscles - sternocleidomastoid and trapezius.

CN IX BE innervation

The glossopharyngeal nerve provides BE motor innervation to one muscle - the stylopharyngeus.

CN XII

The hypoglossal nerve (CN XII) exits the cranial cavity via the hypoglossal canal and provides GSE innervation to the intrinsic muscles of the tongue and three of the four extrinsic muscles of the tongue (muscles with "-glossus" in their name)(styloglossus, hyoglossus, genioglossus) except for palatoglossus which is actually a palate muscle and is therefore, innervated by the vagus nerve (CN X). "-glossus"

CN III

The oculomotor nerves (CN III) pass through the superior orbital fissure to reach the orbit. These nerves provide GSE innervation to 5 of 7 extraocular muscles The oculomotor nerve contributes GVE pre-ganglionic parasympathetic innervation to the ciliary ganglion. The post-ganglionic fibers from the ciliary ganglion travel to the eye via short ciliary nerves to innervate the sphincter pupillae muscle (constrict the pupil) and the ciliary body (lens accommodation).

cranial nerve IX parasympathetic pathway (preganglionic nerve, ganglion, post ganglionic nerve, and target)

cranial nerve IX (glossopharyngeal) preganglionic nerve: lesser petrosal nerve ganglion : otic ganglion post ganglionic nerve: auriculotemporal nerve of V3 target: parotid gland

The olfactory nerves (CN I) are located within

cribriform plate of the ethmoid bone and synapse with the olfactory blub.

The most involved cranial nerves include the

facial nerve (CN VII) with 4 components and an interesting pathway and the glossopharyngeal (CN IX) and vagus (CN X) nerves with five components each (all except GSE)

the chorda tympani also carries preganglionic parasympathetic fibers (GVE) to the submandibular ganglion via the______________

lingual nerve.

There are 12 pairs (right and left) of cranial nerves are considered part of the ___________________ nervous system. They are identified by both a name and CN followed by a roman numeral and labeled above.

peripheral

The oculomotor (CN III) and trigeminal (CN V) nerves have __________ components.

two

Remember that the lingual nerve is a branch from the

mandibular (CN V3) division of the trigeminal nerve.

Remember that GSA innervation of the remaining pharynx includes: • Nasopharynx from the _____________________________________ • Laryngopharynx from the ____________________________

maxillary division (CN V2) of the trigeminal nerve. vagus nerve (CN X)

ur arches have associations with four cranial nerves. These four cranial nerves will provide the __________________innervation for these muscles that originate from these arches.

BE (motor)

cranial nerve 9 Roman numeral • Name • Classification and function • Foramen (or foramina) that they pass through to exit the skull

CN IX glossopharyngeal mixed classification: BE,GSA,GVE,GVA,SA foramen: jugular foramen

cranial nerve 5 Roman numeral • Name • Classification and function • Foramen (or foramina) that they pass through to exit the skull

CN V trigeminal mixed classification: GSA,BE foramen: V1-superior orbital fissure\ V2-foramen rotundum V3- foramen ovale (only one with BE)

cranial nerve 6 Roman numeral • Name • Classification and function • Foramen (or foramina) that they pass through to exit the skull

CN VI abducens motor classification: GSE foramen: superior orbital fissure

cranial nerve 7 Roman numeral • Name • Classification and function • Foramen (or foramina) that they pass through to exit the skull

CN VII facial mixed classification: GSA, GVE, BE,SA foramen: IN- internal acoustic meatus OUT- stylomastoid foramen

cranial nerve 8 Roman numeral • Name • Classification and function • Foramen (or foramina) that they pass through to exit the skull

CN VIII vestibulocochlear nerve sensory classification: SA foramen: internal acoustic meatus

cranial nerve 10 Roman numeral • Name • Classification and function • Foramen (or foramina) that they pass through to exit the skull

CN X Vagus mixed classification: BE,GSA,GVE,GVA,SA foramen: jugular foramen

cranial nerve 11 Roman numeral • Name • Classification and function • Foramen (or foramina) that they pass through to exit the skull

CN XI accessory nerve motor classification: GSE foramen: IN- foramen magnum OUT- jugular foramen

cranial nerve 12 Roman numeral • Name • Classification and function • Foramen (or foramina) that they pass through to exit the skull

CN XII hypoglossal nerve motor classification: GSE foramen: hypoglossal canal

cranial nerve III parasympathetic pathway (preganglionic nerve, ganglion, post ganglionic nerve, and target)

Cranial nerve III (oculomotor) preganglionic nerve: inferior branch ganglion : ciliary ganglion post ganglionic nerve: short ciliary nerves target: ciliary body and constrictor pupillae

cranial nerve VII parasympathetic pathway (preganglionic nerve, ganglion, post ganglionic nerve, and target)

Cranial nerve VII (facial) preganglionic nerve: greater petrosal nerve ganglion : pterygopataine ganglion post ganglionic nerve: branches of V1, V2 target: lacrimal gland (GLANDS ABOVE ORAL FISSURE) OR Cranial nerve VII (facial) preganglionic nerve: chorda tympani +lingual nerve(V3) ganglion : submandibular ganglion post ganglionic nerve: branches of V3 target: submandibular and sublingual glands(GLANDS BELOW THE ORAL FISSURE) spit and cry Cranial nerve

what are the GVE parasympathetic nerves ?

Cranial nerves III, VII, IX, and X are the only cranial nerves that have a GVE parasympathetic component.

CN VII GSA innervation

GSA innervation from the facial nerve provides innervation to the auricle (also called pinna; blue dots) and the external acoustic meatus (external auditory canal). The take home message is that the auricle relays sensory innervation from multiple different nerves.

Therefore, in total, there are six possible classifications for cranial nerves which are

GSE, GSA, GVE, GVA, SA, and BE

CN X GVA innervation

GVA innervation received by the vagus nerve comes from aortic body chemoreceptors and baroreceptors and the carotid body.

Cranial nerves have three-letter classifications that can be either

General (G) - general function like a spinal nerve; or Special (S) - functions only like a cranial nerve (special sense) • Somatic (S) - related to skin and skeletal muscle innervation; or Visceral (V) - related to smooth muscle, cardiac muscle, or glands (gut) • Afferent (A) - sensory function; or Efferent (E) - motor function

CN VI

The abducens nerve (CN VI) passes through the superior orbital fissure and supplies GSE innervation to one extraocular muscle, the lateral rectus.(7/7)

CN VII GVE innervation

The facial nerve (CN VII) provides pre-ganglionic parasympathetic fibers (GVE) to the pterygopalatine ganglion via the greater petrosal nerve Post-ganglionic parasympathetic (GVE) fibers pass from the pterygopalatine ganglion to ALL glands ABOVE the oral fissure except for the parotid gland. This includes: mucous glands in nasal cavity, salivary glands in upper ½ of the oral cavity, and the lacrimal glands in the orbits. The facial nerve (CN VII) also carries pre-ganglionic parasympathetic fibers (GVE) to the submandibular ganglion via the chorda tympani. Post-ganglionic parasympathetic (GVE) fibers from the submandibular ganglion will pass to ALL glands BELOW the oral fissure, the most important of which are the sublingual and submandibular salivary glands. so in general GVE innervations are: lacrimal, submandibular, sublingual, salivary glands, mucous membranes of nasal cavities, hard and soft palate

CN VIII

The vestibulocochlear nerve (CN VIII) enters the temporal bone via the internal acoustic meatus and carries SA hearing and balance innervation from the cochlea and vestibule within the temporal bone back to the brainstem. The facial (CN VII) and vestibulocochlear (CN VIII)cranial nerves both leave the cranial cavity and enter the skull through the internal acoustic meatus.

Four cranial nerves have Branchial Efferent components (or a BE classification). Why?

There are four pharyngeal arches from which muscles arise during events described in embryology. These muscles are not derived from somites (hence no "S" in their classification)

CNVII SA innervation

anterior 2/3rd of the tongue

if a nerve has BE classification, it cannot have GSE classification. why?

because GSE originates from somatic mesoderm

Most cranial nerves originate from the

brain stem

if there was a tumor blocking or in proximity to the internal acoustic meatus. what would be the consquences?

impairment of the CN VII and CN VIII balance and hearing issues, taste issues, salivation issues, issues with facial expression muscles

7 of the 12 cranial nerves are fairly easy to understand because they only have one component (or classification). These include:

olfactory (CN I), optic (CN II), trochlear (CN IV), abducens (CN VI), vestibulocochlear (CN VIII), accessory (CN XI), and hypoglossal (CN XII).

trigeminal nerve is (mostly) GSA; therefore, the lingual nerve carries _____________________ while the chorda tympani (from facial nerve) carries __________________ from the same area of the tongue.

sensation (GSA) taste (SA)

Cranial nerves can be designated as

sensory, motor, or mixed (both sensory and motor).

Pathway of CN VII

the facial nerve (CN VII) passes from the brainstem into the internal acoustic meatus and out through the stylomastoid foramen.

3. All cranial nerves that are mixed have a "B" by their #

(But [CN V] Brother [CN VII] Big [CN IX] Brains [CN X]) and have GSA and BE classifications; no other nerves have GSA and BE components.

4. All cranial nerves that have parasympathetic components

(III, VII, IX, and X) have a GVE component; no other nerves have a GVE component. 3,7,9,10

2. All cranial nerves that are purely motor have an "M" by their #

(Money [CN III] Matters [CN IV] My [CN VI] Matter [CN XI] More [CN XII]) and have a GSE classification; no other nerves have a GSE classification.

The four parasympathetic ganglia of the head include:

1. Ciliary ganglion - receives pre-ganglionic GVE from III 2. Pterygopalatine ganglion - receives pre-ganglionic GVE from VII 3. Otic ganglion - receives pre-ganglionic GVE from IX 4. Submandibular ganglion - receives pre-ganglionic GVE from VII

The four arches and their associated cranial nerves include:

1. First arch - Trigeminal nerve (CN V) providing BE innervation to MASTMATT muscles 2. Second arch - Facial nerve (CN VII) providing BE innervation to facial expression muscles 3. Third arch - Glossopharyngeal nerve (CN IX) providing BE innervation to the stylopharyngeus muscle 4. Fourth/sixth arch - Vagus nerve (CN X)

what happens to the fascial nerve while its in the temporal bone (the petrous part)

1. The geniculate ganglion (from the facial nerve) gives off the greater petrosal nerve which will carry preganglionic parasympathetic fibers (GVE) to the pterygopalatine ganglion. 2. The nerve to the stapedius (BE) is given off from the facial nerve and innervates the stapedius muscle. 3. The chorda tympani is given off from the facial nerve and carries SA taste fibers to the tongue and pre-ganglionic parasympathetic (GVE) fibers to the submandibular ganglion by traveling around the tympanic membrane and heading towards and joining with the lingual nerve (a branch of CN V3) to get to the tongue.

CN II

The optic nerves (CN II) pass through the optic canal within the sphenoid bone and receive the SA innervation of sight via cells within the retina.

CN VII BE innervation

The facial nerve provides BE innervation to ALL muscles of facial expression, the stapedius, posterior belly of digastric, and stylohyoid muscles. The stylohyoid muscle would lie almost parallel to the posterior belly of digastric muscle. Just remember that ANY muscle of facial expression is innervated by BE fibers from the facial nerve (CN VII) and that the facial nerve passes through the parotid gland to reach these muscles

CN IX and its GSA innervation

The glossopharyngeal nerve (CN IX) exits the skull via the jugular foramen and receives GSA innervation from the oropharynx, posterior 1/3rd of tongue and palatine tonsils and the middle ear and auditory (pharyngotympanic or eustachian) tube.

CN IX GVA innervation

The glossopharyngeal nerve also provides GVA innervation to the carotid body and sinus at the branching of the external and internal carotid arteries from the common carotid artery. The vagus nerve also sends a branch to the carotid body.

CN X SA innervation

The internal branch from the superior laryngeal nerve receives the ***SA taste innervation from the epiglottis and pharynx.**** The circle around internal branch of superior laryngeal n. indicates aperture in thyrohyoid membrane.

CN I

The olfactory nerves (CN I) pass through foramina in the cribriform plate of the ethmoid bone and receive the SA innervation of smell. These very short neurons actually synapse with the olfactory bulb and enter the brain through the olfactory tract.

CN V

The trigeminal nerve (CN V) has three named branches that exit foramina of the skull. CN V1 exit at the superior orbital fissure CN V2 exit at the foramen rotundum CN V3 exit at the foramen ovale The ophthalmic (CN V1) and maxillary (CN V2) divisions of the trigeminal nerve are purely sensory (GSA). The mandibular (CN V3) division has sensory and motor components (GSA and BE). All three GSA divisions of the trigeminal nerve provide sensation to the areas of the face.

CN IV

The trochlear nerve (CN IV) passes through the superior orbital fissure to reach the orbit and provides GSE innervation to one extraocular muscle, the superior oblique (6/7 MUSCLE)

CN X and its GSA innervation

The vagus nerve (CN X) exits the skull via the jugular foramen and provides GSA innervation to the larynx, laryngopharynx, deep parts of auricle, part of the external acoustic meatus.

CN X GVE innervation

The vagus nerve provides GVE innervation to smooth muscles and glands in the pharynx and larynx via the internal branch from the superior laryngeal nerve and the recurrent (or inferior) laryngeal nerve. also provides GVE innervation to Thoracic and abdominal visceral innervation (foregut and midgut)

Just like all other GVE nerves, whether sympathetic or parasympathetic, GVE nerves consist of a two-neuron pathway to get to their target:

a pre-synaptic (or pre-ganglionic) neuron which synapses on one of four parasympathetic ganglia of the head and a post-synaptic (or post-ganglionic) neuron which synapses on its target.

A single cranial nerve can have one or up to _____________ of these classifications.

five

if you calculate ALL the combination there are 2^3 or 8 possibilities. however, there is some exceptions

one possibility is not used (SSE) two are combined in function (SA), and one has a varying name (BE): 1. GSA 2. GVA 3. GSE 4. GVE 5. SSA and 6. SVA - combined as SA 7. SSE - doesn't exist 8. SVE (known as Branchial Efferent or BE)

CN IX GVE innervation

parotid salivary gland The glossopharyngeal nerve (CN IX) sends preganglionic parasympathetic fibers (GVE) via the tympanic nerve through the tympanic plexus. These preganglionic parasympathetic fibers emerge from the tympanic plexus as the lesser petrosal nerve, pass through foramen ovale and synapse with post-ganglionic parasympathetic cell bodies in the otic ganglion. The postganglionic parasympathetic fibers pass through the auriculotemporal nerve which is a branch of the mandibular division (CN V3) of the trigeminal nerve to reach and innervate the parotid gland.

Remember the posterior belly of digastric is supplied with BE innervation by

the facial nerve (CN VII).

The BE motor component of the mandibular (CN V3) division of the trigeminal nerve innervates

the muscles of mastication (temporalis, masseter, medial and lateral pterygoids) and the mylohyoid, anterior belly of digastric, tensor tympani and tensor veli palatini. These muscles can be quickly remembered with MAST MATT: MASTication muscles and Mylohyoid, Anterior belly of digastric, Tensor tympani, Tensor veli palatini.