VAN 121: Veterinary Gross Anatomy-II (2+2)

Trigeminal nerve

TRIGEMINAL NERVE (MIXED)

• It is a mixed nerve. It is the largest of the cranial nerves.
• It is connected to the lateral aspect of the pons by a large sensory root and a small motor root; the sensory root forms the semilunar ganglion under which the motor root passes forward.
• The convex face of the ganglion gives off three branches, the ophthalmic, maxillary and mandibular nerves.

Opthalmic nerve

• The ophthalmic nerve is purely sensory and leaves the cranium through the foramen orbitorotundum and divides into frontal, lacrimal and naso ciliary branches.
• The frontal nerve emerges from the orbit through the supraorbital canal and supplies the upper eyelid and the skin.
• The lacrimal nerve supplies the lacrimal gland, skin over the temporal fossa, frontal sinus and a long cornual branch that passes below the lateral border of the body of the frontal bone along with the branches of superficial temporal artery and vein to supply the corium of the horn.
• The naso ciliary nerve runs toward the ethmoidal foramen where it divides into the ethmoidal nerve and the infra-trochlear nerve.
• The ethmoidal nerve passes through the ethmoidal foramen into cranial cavity and leaves it through the cribriform plate of ethmoid and supplies the nasal mucous membrane. ( View the branches of Nerves to the facial region )
• The infratrochlear nerve runs towards the medial canthus and supplies the conjunctiva, lacrimal ducts, lacrimal sac and the third eyelid.

Maxillary nerve

• The maxillary nerve is the largest of the three branches and is also purely sensory like the ophthalmic.

• It emerges out of the cranium through the foramen orbitorotundum runs forward in the pterygopalatine fossa and gives off the following branches.
  • zygomatic or orbital branch which runs to the lateral canthus and supplies lower eyelid and skin.
  • sphenopalatine nerve that is given off in the pterygopalatine fossa, bears the sphenopalatine ganglion. It divides into
    • posterior nasal nerve passes through sphenopalatine foramen to supply the nasal mucous membrane.
    • the greater or anterior palatine which runs through the palatine canal and groove to supply hard palate and gums.
    • the lesser or posterior palatine which passes downward to supply the soft palate.
  • Then the maxillary nerve continues as the infraorbital nerve, which passes through the infraorbital canal, gives off dental branches to the upper cheek teeth, alveolar periosteum and gums, emerges out of the infraorbital foramen and divides into nasal and labial branches to supply nostril and upper lip, respectively.