CRANIAL NERVES

By : Rabia Zulfiqar (Dental Technologist)

Cranial Nerves

Cranial Nerve I: OlfactoryCranial Nerve I: Olfactory

Arises from the olfactory epithelium• Passes through the cribriform plate of the ethmoid

bone• Fibers run through the olfactory bulb and terminate

in the primary olfactory cortex• Functions :sense of smell

Cranial Nerve II: Optic Nerve

Fibers arises from the granular layer of ratine,and converge at optic disc and form optic radiation.

• Optic nerves pass through the optic canals and converge at the optic chiasma.and optic tracts ends into lateral geniculate body, pretactal nucles,and superior colliculus.

• From there, the optic radiation fibers run to the visual cortex

• Functions : impulses for vision

Cranial Nerve III: Occulomotor Nerve

• Fibers extend from superior colliculus pass through cavernous sinus and then into the superior orbital fissure, and go to the extrinsic eye muscles.

• Functions in raising the eyelid, directing the eyeball, constricting the iris, and controlling lens shape.

Cranial Nerve IV: Trochlear

• Fibers emerge from the inferior colliculus and enter the orbits via the superior orbital fissures; innervate the superior oblique muscle

• Primarily a motor nerve that directs the eyeball

Cranial Nerve V: Trigeminal

Pathway :emerge from the anterolateral part of pons and then pass from the post.cranial

fossa to middle cranial fossa and lie at the petrous temporal bone in meckel's cave.

Composed of three divisions: ophthalmic (V1), maxillary (V2), and mandibular (V3)

Opthalmic division: Frontal supratrochlear supraorbital Nasocilliary: Post.ethmoid long cilliary Nerve to cilliary ganglion Infratrochlear Ant. Ethmoid Lacrimal : lateral part of upper eyelid

Maxillary Nerve :

• In Middle Cranial fossa : meningeal branches• In pterogopalatine fossa : Ganglonic Branches• zygomatic :• (a) zygomaticotemporal• (b) zygomaticofacial• Posterior superior Alveoler• In infraorbital Canal : • Middle sup.alveolar• Ant.sup. alveolar• On face : palpebral • labial • Nasal

Mandibullar Division :

• Trunk : 1-Meningeal • 2-Nerve to Medial pterygoid

• Anterior Division :• Deep temporal• Masseteric• Lateral pterygoid• Buccal

• Posterior Division :• Auriculotemporal• (a) Auricular • (b) Superficial Temporal• Lingual • Inferior Alveolar • (a) Mylohyoid • (b) Anterior Belly of Digastric

Cranial Nerve V: Trigeminal

Figure V from Table 13.2

Cranial Nerve VI: Abducent

• Fibers emerge from the lower border of pons and then enter into lateral wall of cavernous sinus and enter into the orbit via the superior orbital fissure

• supply to the lateral rectus muscle of eye.

Cranial Nerve VII: Facial

• Fibers leave the pons, travel through the internal acoustic meatus, and emerge through the stylomastoid foramen to the lateral aspect of the face

• Mixed nerve with five major branches• Motor functions include facial expression, and the

transmittal of autonomic impulses to lacrimal and salivary glands

• Sensory function is taste from the anterior two-thirds of the tongue

Cranial Nerve VII: Facial

Figure VII from Table 13.2

Nuclei :• Brachiomotor• superior salivatory• lacrimatory• tractus solitarius

Branches • within the facial canal:• Greater petrosal nerve• Nerve to the stapedius • chorda tempani

• At the exit from the foramen :• posterior Auricular• digastric• Stylohyoid

• Terminal branches within canal :• Temporal• Zygomatic• Buccal• Marginal Mandibular• Cervical

Cranial Nerve VIII: Vestibulocochlear

• Fibers arise from the hearing and equilibrium apparatus of the inner ear, pass through the internal acoustic meatus, and enter the brainstem at the pons-medulla border

• Two divisions – cochlear (hearing) and vestibular (balance)• Functions are solely sensory – equilibrium and hearing

Cranial Nerve IX: Glossopharyngeal• Fibers emerge from the medulla, leave the skull via the jugular foramen, and

run to the throat

• Nerve IX is a mixed nerve with motor and sensory functions

• Motor – innervates part of the tongue and pharynx, and provides motor fibers to the parotid salivary gland

• Sensory – fibers conduct taste and general sensory impulses from the tongue.

Nuclei :Nucleus AmbigusInferior salivatoryTractus solitarus

Branches Tympanic branchCarotid branchPharyngeal BranchMuscularTonsillarLingual branch

Cranial Nerve X: Vagus

Nuclei :• Nucleus Ambigus• Dorsal Nucles of Vagus• Nucleus of tractus solitarus• nucleus of spinal tract of trigeminal • Branches:• In jugular foramen,superior ganglion gives off branches:• Meningeal• Auricular Branches• Branches Arising In the Neck :• Pharyngeal• Carotid• superior laryngeal• Right recurrent laryngeal• Cardiac

Cranial Nerve X: Vagus

Figure X from Table 13.2

Nerve emerge from the nucleus ambigus and then enter into the jugular foramen. after leaving the jugular foramen.it supply the Its sensory function is in taste.

Cranial Nerve XI: Accessory

• Cranial root arises from the lower part of nucleus ambigus.

• spinal root arises from a long spinal nucleus extending between the segment c1-c5 . both spinal and cranial root pass through the jugular foramen and unite each other and after emerging from the foramen cranial nucleus supply the palate.

• spinal fiber supply the sternocleidomastoid muscle and trapezius muscle.

Cranial Nerve XII: Hypoglossal

• Fibers arise from the medulla and exit the skull via the hypoglossal canal.

• Innervates both extrinsic and intrinsic muscles of the tongue, which contribute to swallowing and speech.

• Branches :

• meningeal branches

• Descending branch