Cranial Nerve I: Olfactory Origin: The olfactory mucosa of the upper part-. of the nasal cavityThe bundles of the nerve pass through openings.of the cribriform plate of the ethmoidal boneEnd in the olfactory bulb in the anterior cranial- . fossaFunction: carrying afferent impulses for the sense-of smell
Cranial Nerve II: Optic• Origin :Arises from the retina of the eye• Optic nerves pass through the optic canals and converge at the optic chiasm• They continue to the thalamus where they synapse.• From there, the optic radiation fibers run to the visual cortex• Function : carrying afferent impulses for vision.
Cranial Nerve VIII: vestibulocochlear• Origin : The anterior surface of the brain between the lower border of the pon and the medulla oblongata.• Cross the posterior cranial fossa and enter the internal acoustic meatus with the facial nerve.• Two divisions – cochlear (hearing) and vestibular (balance)• Function : equilibrium and hearing.
Motor cranial nervesN. Cranial exit Main actionⅢ Superior orbital fissure Motot to superior, inferior and medial recti; inferior obliquus; levator palpebrae superioris Parasympathetic to sphincter pupillea and ciliary musclⅣ Superior orbital fissure Motor to superior obliquusⅥ Superior orbital fissure Motor to lateral rectusⅪ Jugular foramen Motor to sternocleidomastoid and trapeziusⅫ Hypoglossal canal Motot to muscles of tongue
Cranial Nerve III: Oculomotor• Origin : from the anterior aspect of the midbrain.• pass through the superior orbital fissure, and go to the extrinsic eye muscles.• Functions: - raising the eyelid (levator palpebrae superioris)- directing the eyeball ( SR, MR, IR, IO )-constricting the iris ( Ciliary muscle )-and controlling lens shape.
Cranial Nerve IV: Trochlear• Origin : from the posterior aspect of the midbrain.• Enter the orbits via the superior orbital fissures.• Innervate the superior oblique muscle• Function :directs the eyeball downward and laterlly – SO )
Cranial Nerve VI: Abducens• Origin : Between the lower border of the pon and medulla oblongata.• Enter the orbit via the superior orbital fissure• Function: innervating the lateral rectus muscle ( Rotate the eyeball laterally )
Cranial Nerve XI: Accessory• Origin : has 2 roots cranial root : emerging from the anterior aspect of the medulla spinal root : arising from the superior region of the spinal cord ( C1 - C5)• The spinal root passes upward into the cranium via the foramen magnum• The accessory nerve leaves the cranium via the jugular foramen• Function :• Primarily a motor nerve – Supplies fibers to the larynx, pharynx, and soft palate – Innervates the trapezius and sternocleidomastoid, which move the head and neck
Cranial Nerve XII: Hypoglossal• Fibers arise from the anterior of the upper part of the medulla and exit the skull via the hypoglossal canal.• Function : Innervates both intrinsic and extrinsic (Styloglossus, Hyoglossus, Genioglussus ) muscles of the tongue, which contribute to swallowing and speech.• If damaged, difficulties in speech and swallowing; inability to protrude tongue
Cranial Nerve IX: Glossopharyngeal• Origin :from the Anterior surface of the medulla.• leave the skull via the jugular foramen, and run to the throat.• Function : Nerve IX is a mixed nerve with motor and sensory functions Motor – innervates part of the pharynx, and provides motor fibers to the parotid salivary gland Sensory – fibers conduct taste and general sensory impulses from the tongue and pharynx
Cranial Nerve IX: Glossopharyngeal Figure IX from Table 13.2
Cranial Nerve X: Vagus• The only cranial nerve that extends beyond the head and neck• Origin : from the anterior surface of the medulla .• Emerges from the skill via the jugular foramen. Function : The vagus is a mixed nerveMotor :_ Palate, Pharynx._ Digestive, Respiratory, Chardiovascular systmsSensory :_ part of the pharynx, Diaphragm, Visceral organs.
Cranial Nerve VII: Facial• Origin: Between the Medulla and pon.• travel through the internal acoustic meatus, and emerge through the stylomastoid foramen to the lateral aspect of the face.• Functions: . Motor functions include; – Facial expression – Transmittal of parasympathetic impulses to lacrimal and salivary glands (submandibular and sublingual glands). • Sensory function is taste from taste buds of anterior two- thirds of the tongue
Cranial Nerve VII: Facial : Motor Branches1- Temporal: auricular and fronto-occipitalis muscles2- Zygomatic branch : muscles of the zygomatic arch and orbit(Orbicularis oculi).3- Buccal branch : muscles in the cheek and above the mouth((Buccinator muscle and muscle of the upper lip)).4. Mandibular: muscles in the region of the mandible.5. Cervical branch : the platysma muscle
Cranial Nerve V: Trigeminal• Origon : From Anterior surface of the pons by a large sensory and a small motor roots.• The nerve passes forward out of the posterior cranial fossa, on reaching the middle cranial fossa, the large sensory root expands to form the trigemenal ganglion (( The Motor Root Is completely separated from the sensory ganglion)).• The Ophthalmic, maxillary, mandibualr nerves arise from the anterior border of the ganglion.
Cranial Nerve V: Trigeminal• ophthalmic nerve :Leaves the skull from the superior orbital foramen.It supplies the skin of the forehead and upper eyelid and the conjunctiva and the side of the nose.Branches :1. Lacrimal.2. Frontal : Supratruchlear, supraorbital.3. Nasoceliary : Anterior Ethmoidal, infratruchlear nerves.
• A. Infratrochlear B. Anteriorfrontal Ethmoid C. Posterior Ethmoid D. Lacrimal E. Supraorbital F. Supratrochlear G. Nasociliary
Maxillary nerve• Maxillary Nerve :_ leaves the skull from the rotundum foramen and cross the pterygopalatin fossa to enter the orbit through the inferior orbital fissure- It continues as the infraorbital nerve in the infraorbital groove and emerges on the face through the infraorbital foramen which gives sensory fibers to the skin of the face and the side of the nose
Maxillary nerveBranches• Meningeal branches• Zygomatic branche:- Zygomaticofacial & Zygomaticotemporal that supply the skin of face and the lateral gives parasympathetic secretomotor fibers to the lacrimal gland via the lacrimal nerve
• Posterior superior alveolar nerve :supply the maxillary sinus & the upper moler and adjoining part of the gum and thee cheek• middle superior alveolar nerve : Supply the maxillary sinus & the upper premolar ,the gum, the cheek• anterior superior alveolar nerve : supplies the maxillary sinus & the upper canine and the incisor
• Pterygopalatine ganglion : is a parasympathetic ganglion which is suspended from the maxillary nerve in the pterygopalatine fossa _ branches :• Orbital branches : which enter the orbit through the inferior orbital fissure .• greater & lesser palatine nerve : that supply the palate , the tonsil , and the nasal cavity• pharyngeal branch : which supply the roof of the nasopharynx
• Mandibular Nerve:- Emerge from the skull through the foramen ovale in the greater wing of the sphenoid.- Immediately below the foramen, the small motor root units with the sensory root.- The mandibular nerve divides into a small anterior and a large posterior divisions.
• Branches from the main trunk : A meningeal branch : enters the skull through the foramen ovale and supplies the meninges in the middle cranial fossa. The Nerve to the medial pterygoid muscle.
• Branches from the anterior division : the anterior division gives off 3 motor branches and one sensory branch ( Buccal branch ). The masseteric nerve : runs laterally to supply the massater muscle. The two deep temporal nerves: run upward and enter the deep surface of the temporalis muscle. The nerve to the lateral pterygoid muscle enters the deep surface of the muscle.
• The buccal nerve (a sensory nerve ): it runs at the level of the occlusal plane of the mandibular molars, supplies the skin of the cheek, and the buccal gingiva of the mandibular molars.
• Branches from the posterior division: Auriculotemporal ( Sensory ) : It turns upward behind the temporomandibular joint, under cover of the parotid gland; escaping from beneath the gland, it ascends over the zygomatic arch, and divides into superficial temporal branches. Innervation : gives sensory branches to the skin of the auricle, the external auditory meatus, the tympanic membrane, the parotid gland, the TMJ, temporal branches to the skin of the scalp.
Lingual nerve : Emerges between the lower head of the lateral pterygoid and medial pteygoid muscle and lies between the ramus and medial pterygoid muscle in the in the pterygomandibular space, medial to and in front of the inferior alveolar nerve At the lower border of the lateral pterygoid, it is joined with the chorda tympani nerve, and it frequently receives a branch from the inferior alveolar nerve. Innervation : the anterior two thirds of the tongue, the mucous membrane of the floor of the mouth, the lingual gingiva of the mandible.
• Inferior alveolar nerve : It is made up of motor and sensory nerve fibers. Descends on the lateral surface of the sphenomandibular ligament, posterior and parallel to the lingual nerve within the pterygomandibular space. It then enters the mandibular canal through the mandibular foramen and runs forward below the teeth of the lower jew. Innervates the pulpal and osseous tissues of the mandibular teeth , facial soft tissue anterior to the first molar.
Branches of the inferior alveolar berve:It emerges through the mental foramen to divides into 2 terminal branchesIncisive nerve : It’s a direct extension of the inferior alveolar nerve, continuing interiorly within the mandibular canal. Innervation : Pulpal and osseous tissues of the mandibular first premolar, canine, lateral, and central incisors and the facial periodontal tissues of the teeth.
Mental nerve :- It exits the mandible via the mental foramen Innervation:It provides sensory innervation to the mucous membranes and skin of the lower lip and chin.
Mylohyoid nerve :arises from the inferior alveolar nerve just above the mandibular foramen. - It runs forward on the medial surface of the body of the mandible, in the mylohyiod groove. Innervation : supplies the Mylohiod muscle, the anterior belly of the digastric muscle.- In some individuals it may supply accessory sensory innervation to the mandible in the premolar and molar areas.