Intro to the Cranial Nerves

Carotid Branch

Carries ensory fibers from baroreceptors (pressure) in the carotid sinus and chemoreceptors in the carotid body

Aortic Branch

Carries sensory fibers from aortic baroreceptors (pressure) in the carotid sinus and chemoreceptors in the aortic body (adjacent to the aortic arch)

Carotid Nerve

Carries sensory fibers from baroreceptors (pressure) in the carotid sinus and chemoreceptors in the carotid body

Tympanic Branch

Enters the tympanic cavity Contains all preganglionic parasympathetic fibers of the glossopharyngeal nerve and sensory fibers for the tympanic cavity Tympanic nerve plus postganglionic sympathetic fibers from the superior cervical ganglion and a twig from the facial nerve form the tympanic plexus within the tympanic cavity The preganglionic parasympathetic fibers within this plexus then converge as the lesser petrosal nerve which passes out of the petrous portion of the temporal bone in the hiatus of the lesser petrosal nerve side by side with the greater petrosal nerve of CN VII. The lesser petrosal nerve then passes out of the skull through the foramen ovale and enters the infra temporal fossa. It synapses in the otic ganglion with postganglionic parasympathetic neurons. The postganglionic parasympathetic fibers then join the auriculotemporal nerve (V3) which distributes them to the parotid gland.

Location of cell bodies of all taste neurons (pseudounipolar neurons)

Facial Nerve (CN VII) Glossopharyngeal nerve (CN IX) Vagus Nerve (CN X)

Which cranial nerves give rise to pre ganglion parasympathetic fibers?

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

Pharyngeal and Tonsillar branches

Responsible for general sensation from the mucous membrane of much of the pharynx and the palatine tonsils

Lingual Branch

General sensation for posterior one-third of the tongue Taste fibers for the posterior one-third of the tongue

Glossopharyngeal Nerve (CN IX) General Info

Mixed sensory and motor nerve that carries preganglionic parasympathetic fibers It is the nerve to the third branchial arch It emerges from the medulla oblongata from a groove called the post olivary sulcus Its sensory fibers originate from pseudo unipolar neurons in its two sensory ganglia (superior and inferior), which are located in the jugular foramen It exits the skull through the jugular foramen along with the Vagus nerve (CN X) and the accessory nerve (CN XI)

Parasympathetic Components of Facial Nerve (CN VII) Innervation to Head

Nerve Branch - Greater Petrosal Nerve (Preganglionic fibers) Ganglion - Pterygopalatine ganglion (Postganglionic fibers) Target Structures - Lacrimal gland (Tears :-( ), Nasal glands (mucous), Palatine glands (secreting gland) Nerve Branch - Chorda tympani (Preganglionic fibers) Ganglion - Submandibular ganglion (Postganglionic fibers) Target Structures Submandibular gland, Sublingual gland, Lingual glands (all salivary glands)

Origin of Cranial Nerves

Olfactory nerve (CN I) - Telencephalon Optic nerve (CN II) - Diencephalon Oculomotor nerve (CN III) - Midbrain Trochlear nerve (CN IV) - Midbrain Trigeminal nerve (CN V) - Pons Abducens nerve (CN VI) - Pons Facial nerve (CN VII) - Pons Vestibocochlear nerve (CN VIII)- Pons Glossopharyngeal nerve (CN IX) - Medulla Oblongata Vagus nerve (CN X) - Medulla Oblongata Accessory nerve (CN XI) - Medulla Oblongata Hypoglossal nerve (CN XII) - Medulla Oblongata

Meningeal Branch

Sensory to the dura mater in the posterior cranial fossa (actually consists of sensory branches from upper cervical nerves, which "hitchhike" on the vagus)

Branchial motor fibers

Special visceral efferent fibers that innervate skeletal muscles derived from branchial arches. These are actually somatic and voluntary despite the name. Apparently the stupidest thing since the shake weight.

Vagal branches below the recurrent laryngeal nerves

All vagal branches below the recurrent laryngeal nerves carry preganglionic parasympathetic fibers and visceral sensory fibers for the thoracic viscera and abdominal organs including the foregut and midgut derivatives

Left Recurrent Laryngeal Nerve

Arches below and behind aorta to the left of the ligamentum arteriosum and ascends in the groove between the trachea and esophagus

Vestibulocochlear Nerve (CN VIII)

Consists of two divisions: Vestibular and Cochlear This nerve enters the internal acoustic meatus in the company of the facial nerve The vestibular division conveys sensory information related to balance and equilibrium. The cochlear division conveys sensory information related to hearing.

Pharyngeal Branch

Contains sensory and motor fibers This branch, along with the pharyngeal branch of cranial nerve IX and postganglionic sympathetic fibers from the superior cervical ganglion constitute the pharyngeal plexus Supplies motor fibers to all of the muscles of the pharynx except the stylopharyngeus (CN IX) and all of the muscles of the palate except the tensor of the palate (V3) The sensory fibers supply part of the mucosa of the pharynx

Oculomotor Nerve (CN III)

Contains somatic motor and parasympathetic fibers Emerges from the ventral aspect of the midbrain and proceeds through the lateral wall of the cavernous sinus and enters the orbit through the superior orbital fissure where it immediately divides into superior and inferior divisions.

Antagonist of the sphincter of the pupil?

Dilator of the pupil, which is supplied by postganglionic sympathetic fibers arising from the superior cervical ganglion.

Divisons of Superior Laryngeal Branch

Divides into two branches Internal laryngeal branch (sensory) (S-I Sports Illustrated) External laryngeal branch (motor) (M-E)

Name the Cranial Nerves

I - Olfactory nerve II - Optic nerve III - Oculomotor nerve IV - Trochlear nerve V - Trigeminal nerve VI - Abducens nerve VII - Facial nerve VIII - Vestibocochlear nerve IX - Glossopharyngeal nerve X - Vagus nerve XI - Accessory nerve XII - Hypoglossal nerve Oh oh oh, to touch and feel a Female Virgin Girl's Vagina and Hymen

Lesions of the Glossopharyngeal Nerve

Intactness can be tested through the afferent limb of the gag reflex (e.g. stroking the posterior one-third of the tongue with a spatula). The efferent limb of this reflex is the vagus nerve (CN X). The pain referred to the middle ear experienced by a person with tonsillitis is due to the fact that CN IX supplies the tonsillar region as well as the mucous membrane of the middle ear.

Lesion of the Hypoglossal Nerve

Lesion of the hypoglossal nerve result in paralysis and atrophy of the intrinsic and extrinsic muscles of the tongue. The tongue when protruded turns to the side of the lesion due to the unopposed action of the genioglossus muscle from the affected side. All sensations for touch, pressure, temperature, and taste are unaffected.

Lesion of the Spinal Accessory Nerve

Lesion of this nerve will result in weakness in turning the head to the opposite side as well as sagging of the shoulder.

Location of cell bodies of motor neurons (multipolar neurons)

Located in separate and discrete units called nuclei within the brainstem Brainstem consists of midbrain, pons, and medulla oblongata

Major branches of the Vagus Nerve

Meningeal Branch Auricular branch Pharyngeal Branch Carotid Branch Aortic Branch Recurrent Laryngeal Nerves Superior Laryngeal Branch MAP-CARS

Parasympathetic Components of Glossopharyngeal nerve (CN IX) Innervation to Head

Nerve Branch - Lesser Petrosal Nerve (Preganglionic fibers) Ganglion - Otic ganglion (Postganglionic fibers) Target Structures - Parotid Gland (largest of paired salivary glands)

Parasympathetic Components of Oculumotor Nerve (CN III) Innervation to Head

Nerve Branch - Parasympathetic (motor) root of the ciliary ganglion (Preganglionic fibers) Ganglion - Ciliary ganglion (Postganglionic fibers) Target Structures - Ciliary Muscle (changes lens curvature), Sphincter muscle (controls amount of light coming in)

Motor branch to the stylopharyngeus muscle

Only muscle innervated by the glossopharyngeal nerve

Right Recurrent Laryngeal Nerves

Originates just below the beginning of the subclavian artery arching below and behind it to ascend to the larynx in the groove between the trachea and esophagus

Internal Laryngeal Nerve

Pierces the thyrohyoid membrane and supplies the lining of the larynx as far as the vocal cords. Also sends branches to the epiglottis and the valleculae of the tongue. Note: The fibers proceeding to the valleculae and to the laryngeal aspect of the epiglottis contain taste fibers.

Path of Postanglionic Parasympathetic component of Oculomotor Nerve

Postanglionicic parasympathetic fibers depart from the ganglion within the short ciliary nerves and proceed to the eyeball where they supply the ciliary muscle and the sphincter of the pupil.

Path of Preganglionic Parasympathetic component of Oculomotor nerve

Preganglionic parasympathetic fibers of the oculomotor nerve travel with the inferior division and depart from it as the parasympathetic (motor) root of the ciliary ganglion. They synapse with postganglionic parasympathetic neurons in the ciliary ganglion

Olfactory Nerve (CN I)

Primitive sensory nerve containing specialized bipolar neurons in the olfactory mucosa on the superior part of the superior nasal concha and superior part of the nasal septum Bundles of axons from these neurons constitute the olfactory nerves which proceed through the cribriform plate of the ethmoid bone and end in the olfactory bulb of the forebrain The olfactory nerve contains special sensory fibers for smell

Only ocular muscles not supplied by the oculomotor nerve?

Superior Oblique (supplied by CN IV) and the lateral rectus (supplied by CN VI)

External Larygneal Nerve

Supplies the cricothyroid muscle and the crciopharyngeus portion of the inferior constrictor. The remaining intrinsic muscles of the larynx are supplied by the recurrent laryngeal nerve

Auricular branch

Supplies the external auditory meatus and the external surface of the tympanic membrane Important because irritation may initiate a cough reflex or nausea

Lesions of the Vagus Nerve

Symptoms may include increased pulse rate, constant nausea, decreased rate of respiration, a sensation of suffocation, and a hoarse, low voice (sometimes confused with a hangover). There may be difficult swallowing. Tests using to confirm a lesion of the vagus nerve include the efferent (motor) limb of the gag reflex (contraction of the pharyngeal constrictors upon touching the pharyngeal wall or the base of the tongue), faulty movement of the uvula, and a paralyzed vocal cord on the affected side as seen with a laryngoscope.

Abducens Nerve (CN VI)

The abducens nerve supplies the lateral rectus eye muscle with somatic motor fibers. It passes through the cavernous sinus in the company of the internal carotid artery and enters the orbit through the superior orbital fissure.

Accessory Nerve (CN XI)

The accessory nerve is considered to be the nerve of the hypothetical branchial arches beyond the sixth Emerges from the sides of the upper five cervical segments of the spinal cord between the dorsal and ventral rootlets of the respective spinal nerves. It ascends through the foramen magnum and exits the skull through the jugular foramen along with the glossopharyngeal and vagus nerves Innervates the SCM and Trapezius muscle

Hypoglossal Nerve (CN XII)

The hypoglossal nerve is a pure motor nerve. It emerges from the medulla oblongata from the pre-olivary sulcus in line with the ventral roots of the spinal nerves. It leaves the cranial cavity through the hypoglossal canal. The hypoglossal nerve supplies all of the intrinsic and extrinsic muscles of the tongue with the exception of the palatoglossus, which is supplied by the vagus nerve Instrinsic muscles - muscles of tongue, no bone attachment Extrinsic muscles - have bony attachments outside of tongue

Vagus Nerve (CN X) General Info

The nerve of the fourth, fifth, and sixth branchial arches Mixed sensory and motor nerve and contains preganglionic parasympathetic fibers. Emerges from the medulla oblongata from the post-olivary sulcus. It leaves the skull through the jugular foramen with the glossopharyngeal and accessory nerves. The sensory fibers of the vagus nerve originate from pseudo unipolar neurons of the superior and inferior ganglia, which are located in the jugular foramen.

Optic Nerve (CN II)

The optic nerve travels through the optic canal along with the ophthalmic artery (this artery supplies everything in the eyeball). The optic nerve contains special sensory fibers for sight. Typically the favorite nerve of medical students because it doesn't have a billion other branches to memorize.

Trochlear Nerve (CN IV)

The trochlear nerve emerges from the dorsal aspect of the midbrain. The trochlear nerve supplies the superior oblique eye muscle with somatic motor fibers It passes through the lateral wall of the cavernous sinus and enters the orbit through the superior orbital fissure

Recurrent Laryngeal Nerves

The vagus nerves proceed in the neck within the carotid sheath behind and between the internal carotid artery and the internal jugular vein. On the left, the vagus nerve passes in front of the arch of the aorta. Supply motor fibers to all muscles of the larynx except the cricothyroid muscle and sensory fibers to the trachea and larynx below the level of the vocal cords.

Location of cell bodies of all general sensory neurons (pseudounipolar neurons)

Trigeminal Nerve (CN V) Facial Nerve (CN VII) Glossopharyngeal nerve (CN IX) Vagus Nerve (CN X)

Branchiomeric Cranial Nerves and their Branchial Arches

Trigeminal Nerve (CN V) - Branchial Arch 1 Facial Nerve (CN VII) - Branchial Arch 2 Glossopharyngeal nerve (CN IX) - Branchial Arch 3 Vagus Nerve (CN X) - Branchial Arch 4-6 (5 disappears though) Accessory Nerve (CN XI) - Branchial arches beyond arch 6?

Major Branches of the Glossopharyngeal Nerve

Tympanic Branch Carotid Nerve Motor branch to the stylopharyngeus muscle Pharyngeal and Tonsillar branches Lingual Branch Glass trinkets can make stylish people try linking