The trigeminal nerve V

Infratrochlear

Nasociliary ■ Long posterior ciliary

Infratrochlear

Nasociliary Nerve

Fig.57.1

The course and branches of the ophthalmic division of the trigeminal nerve.

Parasympathetic fibres are shown in orange

Supratrochlear Supraorbital Skin of face

Parasympathetic fibres from sphenopalatine ganglion

Frontal

Lacrimal

Superior orbital fissure

Ophthalmic division

Fig.57.1

The course and branches of the ophthalmic division of the trigeminal nerve.

Parasympathetic fibres are shown in orange

Infra-orbital

Sphenopalatine

Sphenopalatine

Greater Palatine Foramen

Lacrimal gland Ophthalmic division F. rotundum Maxillary division

Mandibular division Sphenopalatine ganglion

Nasal branches

Greater palatine Lesser palatine Posterior superior dental Incisive fossa

Fig.57.2

The course and branches of the maxillary division of the trigeminal nerve. Parasympathetic fibres are shown in orange

Foramen ovale Buccal

Lingual

Otic And Submandibular Ganglia Photo

Fig.57.3

The course and main branches of the mandibular division of the trigeminal nerve. The fibres of the chorda tympani are shown in yellow

Lingual

Deep temporal (to temporalis)

Auriculotemporal

Otic ganglion

Muscular branches

Parotid gland

Chorda tympani Inferior alveolar

Submandibular ganglion Mylohyoid nerve Submandibular gland

Fig.57.3

The course and main branches of the mandibular division of the trigeminal nerve. The fibres of the chorda tympani are shown in yellow

The trigeminal nerve (Figs 56.4 and 57.1-3) arises from the brain at the side of the pons by a motor and a sensory root. The sensory root carries the trigeminal ganglion which consists of the cell bodies of the sensory axons and lies in a depression on the petrous temporal bone. It then divides into ophthalmic, maxillary and mandibular divisions. The motor root forms part of the mandibular division.

(a) The ophthalmic division (Fig. 57.1)

This traverses the cavernous sinus and enters the orbit via the superior orbital fissure where it divides into frontal, lacrimal and nasociliary branches. The frontal nerve lies just under the roof of the orbit and divides into supraorbital and supratrochlear nerves which emerge from the orbit and supply the front of the scalp. The lacrimal nerve lies laterally and supplies the skin of the eyelids and face. It also carries parasympathetic secretomotor fibres from the sphenopalatine ganglion to the lacrimal gland. The nasociliary nerve crosses the optic nerve and runs along the medial wall of the orbit to emerge onto the face as the infratrochlear nerve. It gives off the ethmoidal nerves to the ethmoidal sinuses and the long ciliary nerves to the eye which carry sensory fibres from the cornea and sympathetic fibres to the dilator pupillae. All branches of the ophthalmic division are sensory.

(b) The maxillary division (Fig. 57.2)

This leaves the cranial cavity through the foramen rotundum and enters the pterygopalatine fossa. It has the sphenopalatine ganglion attached to it which transmits parasympathetic fibres to the lacrimal gland via communications with the lacrimal nerve. The branches of the maxillary nerve are the greater and lesser palatine nerves to the hard and soft palates, the sphenopalatine nerve to the nasal cavity and thence via the nasal septum, to the incisive fossa to supply the hard palate. The posterior superior dental nerve enters the back of the maxilla and supplies the teeth. The maxillary nerve leaves the sphenopalatine fossa via the inferior orbital fissure, travels in the floor of the orbit where it gives the middle and anterior superior dental nerves, and emerges onto the face through the infraorbital foramen as the infraorbital nerve. All branches of the maxillary division are sensory.

(c) The mandibular division (Fig. 57.3)

This leaves the cranial cavity through the foramen ovale and immediately breaks up into branches. These are: the mainly sensory inferior alveolar nerve, which enters the mandibular foramen to supply the teeth before emerging onto the face as the mental nerve. This nerve does have one motor branch, the mylohyoid nerve, which supplies the mylohyoid and the anterior belly of the digastric. The lingual nerve lies close to the mandible just behind the third molar and then passes forwards to supply the tongue. It is joined by the chorda tympani which carries taste fibres from the anterior two-thirds of the tongue and parasympathetic secretomotor fibres to the submandibular and sublingual salivary glands. These synapse in the submandibular ganglion which is attached to the lingual nerve. The auriculotemporal nerve supplies sensory fibres to the side of the scalp. It also carries parasympath-etic secretomotor fibres, which have synapsed in the otic ganglion, to the parotid gland. The buccal nerve carries sensory fibres from the face. There are muscular branches to the muscles of mastication, including the deep temporal nerves which supply temporalis. The mandibular division thus contains both motor and sensory branches.

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