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.
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
Larynx   Table of Contents for Head & Neck


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