FACIAL BLOCKS N NDEBELE 28 JAN 2009

ANATOMY OF THE TRIGEMINAL NERVE Is the largest of all the cranial nerves and is mixed i.e contains both sensory and motor fibers. Larger sensory root originates in the anterior aspect of the pons. It has 3 major branches: 1. Ophthalmic division (V1) 2. Maxillary division (V2) 3. Mandibular division ( V3). The sensory fibers are distributed mainly to the skin of the face and the motor fibers supply muscles of mastication (masseter, temporalis, medial and lateral pterygoid), mylohyoid, anterior belly of the digastric, tensor velipalatini and tensor tympani muscles.

ANATOMY CONT…. OPHTHALMIC NERVE (V1) Is the smallest of the 3 divisions and is purely sensory. It divides into 3 branches: Frontal Nasocilliary and Lacrimal nerves 1. Frontal Nerve It runs beneath the roof of the orbit and divides into Supratrochlear (smaller and more medial) and Supraorbital (larger and lateral) nerves. The Supratrochlear supplies the skin and conjuctiva of the medial portion of the upper eyelid and the skin over the lower forehead close to the midline. Supra orbital supplies the skin and the conjuctiva of the central portion of the upper eyelid, the skin of the forehead and

ANATOMY CONT…… the scalp as farback as the vertex .

ANATOMY CONT……. 2. NASOCILLIARY NERVE It runs forward on the medial wall of the orbit, continues as the anterior ethmoidal nerve through the anterior ethmoidal foramen. It then descends to enter the nasal cavity where it gives off two internal nasal branches and then continues as the external nasal nerve which supply the skin at the apex and the ala of the nose and the eyeball as well.

ANATOMY CONT.. 3. Lacrimal Nerve Is the smallest of the ophthalmic division and it runs along the lateral wall of the orbit into the lacrimal gland. It is distributed to the conjuctiva and the skin of the lateral portion of the upper eyelid. MAXILLARY DIVISION (V2) Is also purely sensory Originates from the trigeminal ganglion. It gives off Middle Meningeal Nerve within the cranium. It later enters the space located behind and below the orbital cavity known as pterygopalatine fossa to enter the orbit through the inferior orbital fissure. It then continues as the infraorbital nerve in the inferior orbital groove giving sensory fibers to the the skin of the face, side of the nose and the upper gum.

ANATOMY CONT….. Other branches of the Maxillary Nerve are: 1) Zygomatic Branch Passes through the inferior orbital fissure and divides into Zygomaticofacial and Zygomaticotemporal nerves supplying the skin over the prominence of the cheeck and the skin over temple respectively Meningeal Branches Ganglionic Branches Posterior Superior Alveolar Nerve Middle Superior Alveolar Nerve Anterior Superior Alveolar Nerve

ANATOMY CONT….. MANDIBULAR NERVE(V3) Is the largest branch of the trigeminal and is both sensory and motor. Sensory root arises from the trigeminal ganglion and the motor root is from the motor nucleus of the pons and the medulla oblongata. They both leave the skull through foramen ovale. The nerve trunk then divides into a small anterior division and a large posterior division.

ANATOMY CONT… Branches from the posterior division include: 1) Auriculotemporal nerve which ascends behind the temperomandibular joint medial to the parotid gland. It supplies the skin of the auricle, the external auditory meatus, the temperomandibular joint and the scalp. 2)Lingual nerve which enters the mouth to pass along the side of the tongue to reach its tip. It supplies the mucous membrane and the anterior two thirds of the tongue and the floor of the mouth. 3) Inferior alveolar nerve which supply the teeth of the lower jaw and end by dividing into incisive and mental branch.

ANATOMY CONT… Branches of the main anterior trunk include: 1) Meningeal branch 2) Nerve to the medial pterygoid muscle.

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