The 12 Cranial Nerves

Bell's Palsy is an affliction of one of the cranial nerves. Typically, a person with Bell's Palsy has a difficult time tasting food. Based on that bit of information, which cranial nerve is affected?

Facial (CN VII)

Which of the following cranial nerves is involved in tear production (to keep the eyes lubricated)?

Facial (CN VII)

VII Facial

Mixed, both sensory and motor function. Provides motor innervation to the muscles of facial expression, posterior belly of the digastric muscle, stylohyoid muscle, and stapedius muscle. Also receives the sense of taste from the anterior 2/3 of the tongue and provides secretomotor innervation to the salivary glands (except parotid) and the lacrimal gland (tear production). Located in and runs through the internal acoustic canal to the facial canal and exits at the stylomastoid foramen. *contains PS fibers.

IX Glossopharyngeal

Mixed, both sensory and motor function. Receives taste from the posterior 1/3 of the tongue, provides secretomotor innervation to the parotid gland (saliva production), and provides motor innervation to the stylopharyngeus. Some sensation is also relayed to the brain from the palatine tonsils. Located in the jugular foramen. *contains PS fibers.

What does "abducens" refer to?

The abducens nerve carries motor impulses to the lateral rectus eye muscle which moves the eye laterally causing abduction of the eye.

I Olfactory

sensory function. Transmits sense of smell from the nasal cavity. Located in olfactory foramina in the cribriform plate of ethmoid.

II Optic

sensory function. Transmits visual signals from the retina of the eye to the brain. Located in the optic canal.

How many cranial nerves are strictly motor nerves?

six

V Trigeminal

Mixed, both sensory and motor function. Receives sensation from the face and innervates the muscles of mastication(ophthalmic nerve, maxillary nerve and mandibular nerve).

VI Abducens

Motor function. Innervates the lateral rectus, which abducts the eye. Located in the superior orbital fissure.

VIII Vestibulocochlear

Sensory function. Senses sound, rotation, and gravity (essential for balance and movement). More specifically, the vestibular branch carries impulses for equilibrium and the cochlear branch carries impulses for hearing. Located in the internal acoustic canal.

The Glossopharyngeal nerve (CN IX) has sensory and motor functions relating to what two parts of the body?

the tongue and pharynx

Which cranial nerve is responsible for pupillary constriction?

CN III (Oculomotor).

What two cranial nerves carry sensory information about blood pressure to the brain?

CN IX (Glossopharyngeal) and CN X (Vagus).

Which cranial nerves carry gustatory (taste) information?

CN VII (Facial), CN IX (Glossopharyngeal) and CN X (Vagus).

Which cranial nerve is the longest?

CN X (Vagus) which reaches from the medulla to the digestive and urinary organs.

X Vagus

Mixed, both sensory and motor function. Supplies branchiomotor innervation to most laryngeal and pharyngeal muscles. Also provides parasympathetic fibers to nearly all thoracic and abdominal viscera down to the splenic flexure. Receives the special sense of taste from the epiglottis. A major function: controls muscles for voice and resonance and the soft palate. Symptoms of damage: dysphagia (swallowing problems), velopharyngeal insufficiency. Located in the jugular foramen. *contains PS fibers

XII Accessory

Motor function. Controls the sternocleidomastoid and trapezius muscles, and overlaps with functions of the vagus nerve (CN X). Symptoms of damage: inability to shrug, weak head movement. Located in the jugular foramen.

III Oculomotor

Motor function. Innervates the levator palpebrae superioris, superior rectus, medial rectus, inferior rectus, and inferior oblique of the eye, which collectively perform most eye movements. Also innervates the sphincter pupillae (pupil) and the muscles of the ciliary body. Located in the superior orbital fissure. *Contains PS fibers

IV Trochlear

Motor function. Innervates the superior oblique muscle, which depresses, rotates laterally, and intorts the eyeball. Located in the superior orbital fissure.

XIII Hypoglossal

Motor function. Provides motor innervation to the muscles of the tongue. Important for swallowing (bolus formation) and speech articulation. Located in the hypoglossal canal.

Which of the cranial nerves is involved in the blinking reflex?

Occulomotor (CN III)

How many cranial nerves are responsible for eye movements?

Three: CN III (Oculomotor), IV (Trochlear), and VI (Abducens).

Which of the following cranial nerves controls many of our abdominal organs?

Vagus (CN X)