Cranial Nerves

Since you may not have a general knowledge of the nervous system yet, consider the following as a general introduction into what kind of modalities are possible with nerves. A modality is unit of the nervous system that performs a certain type of action: sensation, movement, constriction, etc. There are two general modalities in the peripheral nervous system: motor (efferent) and sensory (afferent). Efferent impulses start in the central nervous system and pass peripherally in spinal or cranial nerves. Afferent impulses start out peripherally and pass into the central nervous system.

Since we are considering cranial nerves here, this is what we will concentrate on. There are 12 pairs of cranial nerves that supply structures in the head, neck, thorax and abdomen. A cranial nerve can be made up of a mixture of functions which are called modalities or may be made up of a single modality. A modality is sensory, motor, special sensory, etc. Below is a breakdown of the modalities of cranial nerves. You may never need to learn this terminology but it is being presented just in case.

Efferent (motor)			Afferent (sensory)
General	Visceral		General		Visceral
General somatic efferent	General visceral efferent	Special visceral efferent	General somatic afferent	Special somatic afferent	General visceral afferent	Special visceral afferent

GSE -- motor to skeletal muscles
GVE -- motor to heart muscle, smooth muscle, glands. In the cranial nerves, these impulses are part of the parasympathetic nervous system.
SVE -- motor to skeletal muscles that develop in branchial arches of the embryo (pharynx, larynx, middle ear)
GSA -- sensations of touch, pain, temperature
SSA -- special sense from organs developing in ectoderm of embryo (vision, hearing)
GVA -- sensory from sensory organs (heart, intestine)
SVA -- special sense from organs developing in association of gastrointestinal tract (smell, taste)

Table of Cranial Nerves

Cranial Nerve	Foramen of Exit From Skull	Other Associated Foramen	Branches	Type of Nerve Impulse	Area Supplied and Function
I (olfactory)	cribriform plate	none	olfactory filaments	special sensory (afferent)	nasal mucosa, smell
II (optic)	optic foramen	none	none	special sensory (afferent)	retina, vision
III (oculomotor)	superior orbital fissure	none	superior division inferior division	general motor (efferent) parasympathetic motor	muscles: superior rectus, levator palpebrae superioris muscles: medial rectus, inferior rectus, inferior oblique, parasympathetic to ciliary ganglion for pupillary constriction
IV (trochlear)	superior orbital fissure	none	muscular	motor (efferent)	superior oblique muscle
V (trigeminal)	see below	see below	see below	general motor (efferent) general sensory (afferent)	see below
V1 (opthalmic)	superior orbital fissure	supraorbital foramen anterior & posterior ethmoidal foramina	meningeal, frontal, lacrimal, nasociliary	general sensory (afferent)	sensation from dura, skin of forehead, scalp, roof of nasal cavity and skin on tip of nose, ethmoid air cells
V2 (maxillary)	foramen rotundum	inferior orbital fissure infraorbital foramen	meningeal, infraorbital, posterior & anterior superior alveolar branches, zygomatic, sensory roots to pterygopalatine ganglion, greater & lesser palatine	general sensory (afferent)	sensation from dura, nasal mucosa, soft palate, skin of lower eyelid and beneath the eye, side of nose, cheek, lip, upper teeth, hard palate
V3 (mandibular)	foramen ovale	mandibular foramen	meningeal, auriculotemporal, buccal, lingual inferior alveolar	general sensory (afferent) general motor (efferent)	sensation from dura, anterior ear and scalp, mucosa lining cheek and gums, skin of cheek, lower teeth, skin of chin, general sensation to the anterior 2/3 of the tongue. motor to temporalis, masseter, medial pterygoid, lateral pterygoid, anterior belly of digastric, mylohyoid, tensor palati, and tensor tympani.
VI (abducens)	superior orbital fissure	none	muscular	general motor (efferent)	lateral rectus muscle
VII (facial)	internal auditory meatus	hiatus of facial canal facial canal stylomastoid foramen	greater petrosal nerve, chorda tympani auricular branch, facial branches, cervical branches	special and general sensory (afferent) general and parasympathetic motor (efferent)	sensation of taste for anterior 2/3 tongue, skin from external meatus, taste from palate. motor to muscles of facial expression, stapedius muscle, muscles of auricle, parasympathetic motor to pterygopalatine ganglion for lacrimal secretion, motor to submandibular ganglion to submandibular and sublingual glands for secretion.
VIII (vestibulocochlear)	internal auditory meatus	none	vestibular, cochlear	general sensory (afferent)	sensation from cochlea for hearing and from semicircular canals and vestibule for equilibrium
IX (glossopharyngeal)	jugular foramen		muscular branches, auricular branch, lingual branch, branch to carotid body and sinus, tympanic branch, lesser petrosal	general and special sensory (afferent) general and parasympathetic motor (efferent)	special sensation of taste from posterior 1/3 of tongue, general sensation from the oropharynx, posterior 1/3 of tongue, sensation from pharyngeal mucosa, special sensation from carotid body and sinus. general motor to stylopharyngeus muscle, parasympathetic to the otic ganglion for parotid gland secretion.
X (vagus)	jugular foramen	none	palatopharyngeal branch, superior laryngeal branch, recurrent laryngeal branch, carotid sinus nerve, cardiac, pulmonary, gastric, renal, hepatic, pancreatic, small intestine, large intestine branches.	sensory (afferent) motor (efferent)	special sensation of taste from base of tongue and epiglottis, general sensation from soft palate, upper larynx, special sensation form carotid body. motor to muscles of soft palate (except tensor palati), muscles of pharynx (except for stylopharyngeus), muscles of larynx, cardiac muscle, smooth muscle of lungs, muscles of intestinal tract as far as the left colic flexure..
XI (spinal accessory)	jugular foramen	foramen magnum	muscular	motor (efferent)	cranial part: provides motor to vagus spinal part: sternomastoid and trapezius muscles
XII (hypoglossal)	hypoglossal foramen	none	muscular	general motor (efferent)	motor to styloglossus, hyoglossus, genioglossus and intrinsic muscles of the tongue.

Now, take a look at what I call cranial nerve maps. These are icons of cranial nerves, their branches, what they supply and what foramina they use. Sensory is yellow and motor is red. Solid red is for skeletal muscle. Dashed red is for parasympathetic fibers. You sort of have to memorize which nerves have motor or sensory or both modalities, then consider what part of the head and neck is involved with each nerve. For example, when you look at the olfactory road map, you will see that it is yellow which means it is purely sensory. Then you consider what kind of sensation of picked up in the periphery which, in this case, is smell. The smell impulses then go back to the central nervous system. If there is red included in the map, that means that something will receive efferent fibers and will either contract or secrete. The impulse starts out in the central nervous system and passes out to a muscle or gland.
You will probably develop your own approach to remembering the cranial nerves and their branches and what they do but this is one method to consider.

Cranial Nerve Maps

	cp--cribriform plate of ethmoid
	on--optic nerve oc--optic chiasm ot--optic tract
	sof--superior orbital fissure sd--superior division sr--superior rectus id--inferior division mr--medial rectus io--inferior oblique ir--inferior rectus cg--ciliary ganglion sc--short ciliary nerves
	so--superior oblique
Red solid -- motor to skeletal muscles Red dotted -- parasympathetic motor to cardiac and smooth muscle Yellow -- sensory (afferent)	tg--trigeminal ganglion sof--superior orbital fissure V1--ophthalmic division f--frontal supof--supraorbital foramen so--supraorbital nerve st--supratrochlear nc--nasociliary pe--posterior ethmoidal nerve ae--anterior ethmoidal nerve it--infratrochlear nerve sr--sensory root of ciliary ganglion lac--lacrimal nerve V2--maxillary division fr--foramen rotundum m--maxillary nerve tp--sensory root to pterygopalatine ganglion tpg--pterygopalatine ganglion gpn--greater palatine nerve lpn--lesser palatine nerve z--zygomatice nerve io--inferior orbital nerve psa--posterior superior alveolar nerve asa--anterior superior alveolar nerve iof--infraorbital foramen V3--mandibular division fo--foramen ovale og--otic ganglion ntp--nerve to tensor palati muscle ntt--nerve to tensor tympani muscle b--buccal nerve l--lingual nerve ct--chorda tympani sg--submandibular ganglion ia--inferior alveolar nerve mf--mandibular foramen menf--mental foramen mn--mental nerve nmn--nerve to mylohyoid adg--anterior belly of digastric muscle mhm--mylohyoid muscle at--auriculotemporal nerve
	sof--superior orbital fissure
Red solid -- motor to skeletal muscles Red dotted -- parasympathetic motor to cardiac and smooth muscle Yellow -- sensory (afferent)	iam--internal auditory meatus gg--geniculate ganglion hfc--hiatus of facial canal gp--greater petrosal nerve fl--foramen lacerum pc--pterygoid canal npc--nerve of pterygoid canal ppg--pterygopalatine ganglion mn--maxillary nerve ln--lacrimal nerve ns--nerve to stapedius muscle ab--auricular branch ct--chorda tympani sg--submandibular ganglion slg--sublingual gland smg--smandibular gland tb--temporal branches zb--zygomatic branches bb--buccal branches mb-mandibular branch cb-cervical branch pbd-nerve to posterior belly of digastric muscle
	iam--internal auditory (acoustic) meatus
Red solid -- motor to skeletal muscles Red dotted -- parasympathetic motor to cardiac and smooth muscle Yellow -- sensory (afferent)	jf--jugular foramen sg--superior ganglion ig--inferior ganglion tp--tympanic plexus lpn--lesser petrosal nerve fo--foramen ovale og--otic ganglion pg--parotid gland sp--nerve to stylopharyngeus muscle pb--pharyngeal branch ncbcs--nerve to carotid body carotid sinus
Red solid -- motor to skeletal muscles Red dotted -- parasympathetic motor to cardiac and smooth muscle Yellow -- sensory (afferent)	jf--jugular foramen sg--superior ganglion ig--inferior ganglion pb--pharyngeal branch spc--superior pharyngeal constrictor sl--superior laryngeal nerve il--internal laryngeal el--external laryngeal ct--cricothyroid muscle mpc--middle pharyngeal constrictor rl--recurrent laryngeal nerve pc--pharyngeal constrictors csn--carotid sinus nerve
	fm--foramen magnum jf--jugular foramen
	C1--first cervical nerve hf--hypoglossal canal

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