Crainal Nerve-2015-ruan-2.ppt

III. Mixed cranial nerves : 1. Oculomotor nerve (Cn.III)---- a mixture of motors

2. Trigeminal nerve (Cn.V) -- a mixture of motor and sensory axons 3. Facial nerve (Cn. VII)-- a mixture of motor and sensory axon. 4. Glossopharyngeal nerve (Cn.IX) 5. Vagus nerve (Cn. X)

2. Trigeminal nerve (Cn.V) -- a mixture of motor and sensory axons – contains a large sensory root, which originates in the trigeminal ganglion , and a smaller motor root, which originates in the motor nucleus of Cn. V. – Three divisions: • Ophthalmic d. (V1) • Maxillary d. (V2)

sensory

• Mandibular d.(V3)

mixed

⑴ Ophthalmic n. (pure sensory) • Sensory distributions – forehead – upper eyelid – conjunctiva – cornea – nose – nasal mucosa – frontal sinuses – parts of the meninges.

Branches: ① frontal n. ② lacrimal n. ③ nasocilliary n.

Divisions of Ophthalmic n.

(2) Maxillary n. (pure sensory) • Sensory distributions: – – – – – – –

lower eyelid Cheek nares upper lip upper teeth and gums nasal mucosa palate and roof of the pharynx – maxillary, ethmoid and sphenoid sinuses – parts of the meninges.

(2) maxillary n.

Branchess: ① infraorbital n. ② zygomatic n. ③ superior alveolar n. ④ pterygopalatine n. Pterygopalatine ganglion

(3) Mandibular n. • Sensory distributions: – lower lip – lower teeth and gums, – chin and jaw, – Anterior 2/3 of Tongue – parts of the external ear – parts of the meninges.

Anterior 2/3 Tongue

(3) Mandibular n. -- a mixture of motor and sensory axon Braches: • Sensory branches: ① auriculotemporal n. ② buccal n. ③ lingual n. ④ inferior alveolar n.

(3) Mandibular n.-- a mixture of motor and sensory axon Braches: • Motor branches: These fibers originate in the motor nucleus of trigeminal nerve ① nerve to masticatory muscles ② nerve to mylohyoid m. and anterior belly of digastric m. ③ nervde to tensor veli palatini and tensor tympani

tensor veli palatini

tensor tympani

CN V TRIGEMINAL

innervations

Anterior 2/3 Tongue

Sensory - Sensory to Face, Scalp, Oral & Nasal Cavities, Teeth, Sinuses, Meninges, & Anterior 2/3 of Tongue

TEMPORALIS

Motor - Muscles of Mastication MASSETER

3. Facial nerve (Cn. VII)-- a mixture of motor and sensory axon Components: 1) the special visceral efferent fibers originate in the facial nucleus and innervate the muscles of expression 2) the general visceral efferent fibers arise from the superior salivatory nucleus and control the secretion of the lacrimal gland, the submandibular and sublingual salivary glands 3) the special visceral afferent fibers convey the taste from the anterior two-third of the tongue

Facial nerve

Course: • The facial nerve passes through the internal acoustic meatus, and enters the facial canal. • The nerve leaves the facial canal through the stylomastoid foramen, then runs forward into the parotid gland, where it divides into five major branches to innervates muscles of expression .

Branches--Inside Skull ①Greater petrosal nerve • arise in the superior salivary nucleus of the pontine tegmentum. • Preganglionic parasympathetic fibres pass through the geniculate ganglion and become greater petrosal nerve which synapses with the pterygopalatine ganglion. • parasympathetic postganglionic fibers innervate the lacrimal gland and the mucosal glands of the nose, palate, and pharynx.

Branches--Inside Skull ② chorda tympani: – Special sensory fibers from the taste buds in the front of the tongue (anterior 2/3) . – joins the facial nerve inside the facial canal where it runs from posterior to anterior across the tympanic membrane

Branches--Inside Skull ② chorda tympani: – Motor fibers (parasympathetic) innervate the submandibular and sublingual glands.

Branches--Inside Skull ③ Stapedial nerve: – Innervates the stapedius in the middle ear

Branches--Outside skull ① Posterior auricular nerve controls movements of some of the scalp muscles around the ear. ②Five major facial branches (in parotid gland) - from top to bottom: – Temporal branch of the facial n. – Zygomatic branch of the facial n. – Buccal branch of the facial n. – Marginal mandibular branch of the facial n. – Cervical branch of the facial nerve

③Branches to Posterior belly of Digastric and Stylohyoid muscle

Ganglions: ①Geniculate ganglion : • an L-shaped collection of fibers and sensory neurons of the facial nerve located in the facial canal of the petrous temporal bone. • contains fibres for taste and somatic sensation

②Parasympathetic ganglia connecting to facial nerves (l) Pterygopalatine ganglion: – The greater petrosal nerves enter the ganglion and are relayed here. – The postganglionic fibers innervate the lacrimal gland and glands in the mucous membrane of the nasal cavity and palate and control their secretions.

Parasympathetic ganglia connecting to facial nerves (2) Submandibular ganglion: – Chorda tympani fibers enter the ganglion and are relayed here. – The postganglionic fibers innervate the submandibular and sublingual glands and control their secretions.

CN VII

VII

FACIAL

Innervations Motor : Anterior 2/3

MUSCLES OF FACE

TASTE –Tongue & Soft Palate

•Muscles of Facial Expression •Lacrimal Gland Submandibular & Sublingual Glands

Sensory: Taste -Anterior 2/3 of Tongue

GLANDS: Lacrimal, Submandibular, & Sublingual

Clinical features of the facial nerve lesion (1) Lesion in the facial canal : ① wrinkles on the forehead are smoothed out, the eye can not shut voluntarily, the nasolabial fold becomes smooth on the affected side; ② when a smile is attempted ,the angle of mouth draw to the unaffected side; ③ there is a loss of taste in the anterior 2/3 of the tongue; ④ reduced salivation; ⑤ the sounds are very loud in the affected ear due to the paralysis of the stapedius .

(1) Lesion in the facial canal :

(2) Lesion outside the facial canal : • there is paralysis of the muscles of expression only.

Glossopharyngeal nerve (Cn.IX)-a mixture of motor and sensory axons Components: ① Special visceral efferent (SVE) fibers arise from the ambiguous nucleus and supply the stylopharyngeus m. ② General visceral efferent (GVE) fibers arise from inferior salivatory nucleus and control the secretion of the parotid gland. ③ General visceral afferent (GVA) fibers arise from the inferior ganglion to supply the mucous membrane of the pharynx, the tonsil, the middle ear, the posterior 1/3 of the tongue, and the carotid glomus and the carotid sinus ④ Special visceral afferent (SVA) fibers arise from inferior ganglion , and innervate the posterior 1/3 of the tongue (taste) ⑤General somatic afferent (GSA) fibers arise from the superior ganglion and supply the skin of the posterior surface of the auricle.

Course: • The nerve leaves the skull through the jugular foramen, and passes forwards, beneath the styloid process, and between the external and internal carotid arteries, reach to the root of the tongue.

Branches : (l) tympanic nerve (GSA &GVE) – It enters the tympanic cavity to form the tympanic plexus. – The plexus gives off many branches to the mucous membrane of the middle ear. – The lesser petrosal nerve arises from this plexus and is relayed in the otic ganglion (Parasympathetic ganglia) – The cells in the ganglion send the postganglionic fibers to distribute to the parotid gland.

Branches : (2) Carotid sinus b.(GVA) – descends along the internal carotid artery to the wall of carotid sinus and the carotid glomus. (3) Lingual b.(GVA &SVA) – distributed to the posterior 1/3 of the tongue. They contains both fibers of special sense (taste) and of general visceral sensations. (4) Pharyngeal b.(SVE) – distributed to the pharynx and the stylopharyngeus.

pharyngeal b. Lingual b.

carotid sinus b.

Innervations • Sensory from taste & other receptors of rear 1/3 of tongue, auditory tube and middle ear, & upper throat • Motor to muscle of the throat • Parasymp. to parotid salivary gland • Sensory from chemoreceptors (oxygen) of carotid body and BP receptors of carotid sinus

Course: • It leaves the skull through the

jugular foramen then passes Vagus nerve

into the carotid sheath between the internal carotid

artery and the internal jugular vein down to the neck, chest and abdomen,

jugular foramen

Vagus nerve -a mixture of motor and sensory axons Components : ①GVE fibers arise from the dorsal nucleus of vagus nerve, and are relayed in the paraorganic or interorganic parasympathetic ganglions in the throacic and abdominal cavities. The postganglionic fibers supply the smooth muscles, cardiac muscles and glands of the viscera.

Components : ②GVA fibers arise from the inferior ganglion of vagus nerve and relayed in the nucleus of solitary tract. The peripheral processes of ganglionic cells are distributed to the viscera of the neck, thorax,

and abdomen.

Components : ③GSA fibers originate from the superior ganglion of vagus nerve and relayed in the spinal nucleus of trigeminal nerve. The peripheral processes of this ganglionic cells are distributed in the skin of the auricle and external acoustic meatus and cerebral dura mater.

Components : ④ SVE fibers arise from the ambiguous nucleus and supply the muscles of the larynx and the

pharynx.

Branches: (1) Branches in the neck ① Pharyngeal br. ② superior laryngeal n. – distributed to the mucous

membrane of the larynx above the level of the fissure of glottis and the

cricothyroid .

Sup. laryngeal n.

vagus n.

Recurrent laryngeal n.

Recurrent laryngeal n.

(2) Branches in the thorax ① Recurrent laryngeal n. – supplies all the muscles of larynx except for the cricothyroid m. – is distributed to the mucous membrane of the larynx below the level of glottis. ② Broncheal br., ③ Esophageal br.

④ Cervical cardiac br. • form the cardiac plexuses and distributed to the heart and the wall of the aorta.

(3) Branches in the abdomen • anterior vagal trunk divides into

①anterior gastric br ②hepatic br.

(3) Branches in the abdomen • posterior vagal trunk divides into ③posterior gastric br. ④celiac br. • innervate the stomach, liver and gallbladder.

Post. trunk Celiac branch

Ant. trunk

Hepatic branch

Post. Gastric branch

Ant. gastric branch

(3) Branches in the abdomen • innervate the stomach, liver and gallbladder.

Innervation: • Sensory from taste and other sensory receptors in lower throat

• Sensory from the viscera • Motor to muscles of larynx and pharynx • Parasympathetic to all organs of chest and abdomen

Functions: • a reduction in heart rate, blood pressure, or both. • This occurs commonly in the setting of gastrointestinal illness such as viral gastroenteritis or acute cholecystitis,. • When the circulatory changes are great enough, vasovagal syncope results. Relative dehydration tends to amplify these responses.

Clinical feature of the vagus lesion • hoarse voice (injury of the recurrent laryngeal nerve ) • difficulty in swallowing (dysphagia) • choking when drinking fluid, • Uvula deviates away from the side of lesion • failure of palate elevation.

Function summary of cranial nerves: