Cranial Nerves

What nerves are in the parasympathetic nervous system?

Vagus nerve (CN X) Glossopharyngeal nerve (CN IX) Facial nerve (CN VII) Oculomotor nerve (CN III)

What vesicular stage does the optic vesicle develop from?

Diencephalon

What embryologic structure does the olfactory placode develop from?

Ectoderm

What embryologic structure does CN III-XII develop from?

Neural crest

What is cranial nerve I?

Olfactory nerve

What is cranial nerve II?

Optic nerve

What is cranial nerve III?

Oculomotor nerve

What is cranial nerve IV?

Trochlear nerve

What is cranial nerve V?

Trigeminal nerve

What is cranial nerve VI?

Abducens nerve

What is cranial nerve VII?

Facial nerve

What is cranial nerve VIII?

Vestibulocochlear nerve

What is cranial nerve IX?

Glossopharyngeal nerve

What is cranial nerve X?

Vagus nerve

What is cranial nerve XI?

Accessory nerve

What is cranial nerve XII?

Hypoglossal nerve

What type of nerve is the olfactory nerve?

Sensory

What type of nerve is the optic nerve?

Sensory

What type of nerve is the oculomotor nerve?

Motor

What type of nerve is the trochlear nerve?

Motor

What type of nerve is the trigeminal nerve?

Both (sensory and motor)

What type of nerve is the abducens nerve?

Motor

What type of nerve is the facial nerve?

Both (sensory and motor)

What type of nerve is the vestibulocochlear nerve?

Sensory

What type of nerve is the glossopharyngeal nerve?

Both (sensory and motor)

What type of nerve is the vagus nerve?

Both (sensory and motor)

What type of nerve is the accessory nerve?

Motor

What type of nerve is the hypoglossal nerve?

Motor

Where does the olfactory nerve originate?

Olfactory epithelium

What structure does the olfactory nerve pass through to synapse with the olfactory bulb?

Cribiform plate

What is the function of the olfactory nerve?

Smell

What lobe does the olfactory bulb send signals to?

Piriform lobe

What structure does the olfactory bulb send signals to the pirifrom lobe through?

Olfactory peduncle

What does anosmia mean?

Complete loss of smell

What does hyposmia mean?

Partial loss of smell

What does dysosmia mean?

Distorted sense of small

What does hyperosmia mean?

Increased sense of smell

Where does the optic nerve originate?

Retina

What is the function of the optic nerve?

Vision and spatial awareness

Where is the optic nerve positioned on the eye?

Caudoventrally and caudomedially

What is the purpose of the optic chiasm?

Decussation: allows for broader vision, uniform processing, and binocular vision

What percent of fibers decussate at the optic chiasm?

75%

What lobe processes visual information?

Occipital lobe

What parts of the brain also receive visual information?

Rostral colliculi, thalamus, and lateral geniculate nucleus

What reaction should occur during a pupillary reflex test?

Direct eye: 100% pupillary constriction Consensual eye: 50% pupillary constriction

Where does the oculomotor nerve originate?

Edinger westphal nucleus (Tegmentum)

What ganglion does the oculomotor nerve synapse in?

Ciliary ganglion

What is the function of the oculomotor nerve?

Movement of extrinsic eye muscles and pupillary constriction

What muscles are innervated by the oculomotor nerve?

1. Dorsal rectus muscle 2. Levator palpebral superioris muscle 3. Medial rectus muscle 4. Ventral rectus muscle 5. Ventral oblique muscle 6. Sphincter pupillary muscle 7. Ciliary muscle

What is anisocoria?

Unequal pupil size under equal light conditions

What nerve synapses at the trigeminal ganglion and gives off long and short ciliary nerves?

Nasociliary nerve

What root is the nasociliary nerve?

Sensory root

What roots passes through the ciliary ganglion without synapsing?

Sensory and sympathetic roots

What root synapses in the ciliary ganglion?

Parasympathetic root

What space do the sensory, sympathetic, and parasympathetic roots occupy within the eye?

Perichorodial space

What structures of the eye are supplied by the sensory, sympathetic, and parasympathetic roots?

Ciliary body and iris

Which root also supplied the cornea of the eye?

Sensory root

What is the smallest cranial nerve?

Trochlear nerve

Which nerve has the greatest intercranial length?

Trochlear nerve

What is the only cranial nerve that originates from the dorsal aspects of the brain?

Trochlear nerve

Where does the trochlear nerve originate?

Trochlear nuclei (tegmentum)

What muscle does the trochlear nerve innervate?

Dorsal oblique muscle

Where does the trigeminal nerve originate?

Motor nucleus- Pons Sensory nuclei- Pons, midbrain, and medulla

What are the branches of the trigeminal nerve?

V1: Opthalmic nerve V2: Maxillary nerve V3: Mandibular nerve

What type of nerve is the opthalmic nerve?

Sensory

What type of nerve is the maxillary nerve?

Sensory

What type of nerve is the mandibular nerve?

Both (sensory and motor)

What is the largest sensory nerve of the head?

Trigeminal nerve

What structures are supplied by the opthalmic nerve-?

1. Cornea 2. Upper eyelid 3. Forehead

What conditions can occur from damage to the trigeminal nerve?

Dropped jaw (paralysis of masticatory muscles) One side of the head becomes sunken (atrophy of masticatory muscles)

Where does the abducens nerve originate?

Pons

What muscles are innervated by the abducens nerve?

1. Lateral rectus muscle 2. Retractor bulbi muscles

What condition can be caused by damage to the abducens nerve?

Strabismus (misalignment of eye direction)

Where does the facial nerve originate?

Medulla oblongata

What nerve does the facial nerve loop around?

Abducens nerve

What is Genu Syndrome?

Impairment of both the facial and abducens nerve

What structures are innervated by the facial nerve?

Parasympathetic- Lacrimal and sublingual glands Sensory- Tongue (rostral 2/3) Motor- Digastricus m., platysma m., stylohyoid m., stapedius m.

What conditions can occur due to facial nerve damage?

Facial aysmmetry, Iagopthalmos, loss of blink reflex, mimetic muscle paralysis

Where does the vestibulocochlear nerve originate?

Medulla oblongata

What are the divisions of the vestibulocochlear nerve?

1. Vestibular division 2. Cochlear division

What is the purpose of the vestibular division of the vestibulocochlear nerve?

Helps with balance and equilibrium

What is the purpose of the cochlear division of the vestibulocochlear nerve?

Hearing

What conditions can occur due to vestibular dysfunction?

Head tilt, ataxia, nystagmus, and head tremors

What condition can occur due to cochlear dysfunction?

Partial or complete deafness

Where does the glossopharyngeal nerve originate?

Medulla oblongata

What are the 2 branches of the glossopharyngeal nerve?

1. Lingual branch 2. Pharyngeal branch

What structures are innervated by the pharyngeal branch of the glossopharyngeal nerve?

1. Stylopharyngeus m. 2. Pharynx

What structures are innervated by the lingual branch of the glossopharyngeal nerve?

Parasympathetic- zygomatic and parotid glands Sensory- Baro and chemo receptors, tongue (caudal 1/3) Motor- tongue (caudal)

What conditions can be caused by damage to the glossopharyngeal nerve?

Loss of taste (caudal 1/3), drooling, dysphagia, regurgitation, pharyngeal paralysis

Where does the vagus nerve originate?

Medulla oblongata

What is the only cranial nerve that leaves the head?

Vagus nerve

What structures are innervated by the vagus nerve?

Parasympathetic- thoracic and abdominal organs Sensory- trachea, esophagus, viscera Motor- laryngeal m., pharyngeal m., esophageal m.

What branch of the vagus nerve loops around the right subclavian artery?

Right recurrent laryngeal nerve

What branch of the vagus nerve loops around the aorta?

Left recurrent laryngeal nerve

What are conditions caused by vagus nerve damage?

Roaring (horses), laryngeal paralysis, bloat, colic, megaesophagus, impaired eructation

Where does the accessory nerve originate?

Spinal cord

What muscles are innervated by the accessory nerve?

Sternocephalicus m. (mastoid part) 2. Cleidocephalicus m. (mastoid part) 3. Trapezius m. 4. Omotransversarius m.

Where does the hypoglossal nerve originate?

Medulla oblongata

What muscles are innervated by the hypoglossal nerve?

Intrinsic and extrinsic tongue muscles

What condition can occur due to hypoglossal nerve damage?

Paralysis of the tongue