The Fifth Cranial Nerves The Trigeminal By Prof. Dr. Muhammad Imran Qureshi



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The Fifth Cranial Nerves
The Trigeminal

By

Prof. Dr. Muhammad Imran Qureshi

The Maxillary Nerve - Vb or VII
The Maxillary nerve, arises from the middle of the semilunar ganglion and passes forward between the true dura and endocranium below the lower border of the cavernous sinus.

After the course of about a centimeter, the maxillary nerve comes across the foramen Rotundum, through which it passes into the Pterygopalatine fossa.

Within the fossa, VII is located superolateral to a parasympathetic ganglion called the Pterygopalatine (Sphenopalatine) ganglion. This ganglion gets its preganglionic supply from the facial nerve.

However, a thick short nerve bundle passes between the maxillary nerve and Pterygopalatine ganglion. This bundle carries postganglionic parasympathetic axons from the ganglion to VII for distribution with its branches, as well as the sensory axons from VII down to the ganglion to be distributed with the nerves that originate directly from it.

The Pterygopalatine ganglion is visceral motor (Parasympathetic) and contains no sensory cell bodies.

The three actual branches of the Maxillary nerve are the Posterior Superior Alveolar, the Zygomatic, and the Infraorbital.

Having given off branches to the Pterygopalatine ganglion, the maxillary nerve passes laterally and slightly upward toward the infraorbital groove in the floor of the orbit.

Just before reaching the groove, it gives off the Posterior Superior Alveolar and Zygomatic nerves.

The Posterior Superior Alveolar nerve joins the artery of the same name to pass downward applied to the back surface of the maxilla. Both structures may branch once or twice before perforating the back wall of the maxilla to reach the molar teeth.

The Zygomatic nerve courses to the lateral part of the inferior orbital fissure, through which it passes into the orbit where it runs between the periorbita and bone anterior to the fissure.

The nerve then may:

Either pass through a single foramen in the orbital surface Zygomatic bone and within that bone bifurcate into Zygomaticofacial and Zygomaticotemporal nerves, or bifurcate into the Zygomaticofacial and Zygomaticotemporal nerves, each of which passes through its own foramen in the zygomatic bone. Regardless of the two situations, the Zygomaticofacial nerve emerges from the zygomatic bone on the outer surface of its ascending (frontal) process, whereas the Zygomaticotemporal nerve emerges from the posterior surface of this process.

The Zygomaticofacial nerve is cutaneous to a small region of the face over the side of the cheek bone. The Zygomaticotemporal nerve is cutaneous to a small region of the temple behind the orbit.

Among the parasympathetic ganglion cells that form the Pterygopalatine ganglion are some whose axons are destined for the lacrimal gland. These travel to the Maxillary nerve and then out its Zygomatic branch into the orbit. These fibres run in the zygomaticotemporal branch of the zygomatic nerve. They ultimately leave the nerve to join the Lacrimal branch of VI, and are conducted by it to the lacrimal gland.

After the Maxillary nerve has given off its Posterior Superior Alveolar and Zygomatic branches, it continues into the infraorbital groove as the Infraorbital nerve.

Like the Infraorbital artery, the nerve gives off a Middle Superior Alveolar branch for the premolar teeth, and an Anterior Superior Alveolar branch for the canines and incisors.

This branch also sends a twig to the anterior part of inferior nasal meatus .

The Infraorbital nerve then exits onto the face below the orbit.

Here it is cutaneous to the lower eyelid, upper lip, side of the nose, front of the cheek, and skin lining the nasal vestibule. The maxillary sinus is supplied by branches from all three superior alveolar nerves. Although these nerves are primarily sensory, they do carry postganglionic parasympathetic fibers to mucous glands of the maxillary sinus.

Branches of the Maxillary Nerve That Emerge from the Pterygopalatine Ganglion:

The pterygopalatine ganglion gives off branches that distribute to the same structures supplied by branches of the inner terminal division of the maxillary artery. A Greater Palatine nerve and a few Lesser Palatine nerves pass with the Descending Palatine artery out the bottom of the Pterygopalatine fossa into the Greater palatine canal.

The Lesser Palatine nerves go to the soft palate after passing through Lesser Palatine canals and foramina, the Greater Palatine nerve passes through the Greater Palatine foramen onto the roof of the mouth, where it turns forward with the artery.

Other branches from the Pterygopalatine ganglion pass medially through the Sphenopalatine foramen (along with the Sphenopalatine artery) to supply the posterior part of the lateral nasal wall and posterior part of the nasal septum.

One of the nerves to the septum is larger than the others and accompanies the largest posterior septal artery to the incisive canals. This is the Nasopalatine nerve, and it too passes through the incisive foramen out the roof of the mouth behind the incisor teeth.

Although the nerves that supply the nasal cavity and palate are largely sensory, they also carry the postganglionic parasympathetic axons for mucous glands. These arise from cells in the Pterygopalatine ganglion.

The taste fibers from the palate run in the Palatal branches of the Maxillary nerve back to the Pterygopalatine ganglion, which they pass through to enter the Greater Superficial Petrosal branch of the Facial nerve.

Summary of the Maxillary Nerve - Vb or VII

Exits the cranial cavity through the foramen rotundum.

The recurrent branch supplies the anterior part of the middle cranial fossa.

The maxillary nerve goes to the nasal region (ptyerygopalatine fossa) where it is joined by hitchhikers from the facial nerve (pterygopalatine ganglion).



These parasympathetic and taste nerves supply the palatine, nasal and lacrimal glands – and get there by hitchhiking with most of the branches of the maxillary nerve.

Branches of the Maxillary nerve:

Zygomatic nerve – goes through the inferior orbital fissure into the orbit it divides into zygomaticofacial and zygomaticotemporal nerves and also passes its hitchhiker to the lacrimal branch of the ophthalmic nerve.

Posterior superior alveolar nerves – stream down over the back and sides of the maxilla to the molar teeth.

Anterior superior alveolar nerves – run through the orbit with the infraorbital nerve and then stream over the front of the maxilla to the anterior teeth.

Infraorbital nerve – runs through the orbit and sinks into the orbital floor before emerging onto the face at the infraorbital foramen. It supplies the upper lip, cheek, adjacent lining of the mouth, and the lower eyelid

Palatine nerves (greater and lesser) go down through the palatine foramina to the posterior part of the palate. They supply the posterior part of the palate and gums.

Nasopalatine nerve – enters the nasal cavity and runs down the septum towards the incisor teeth to the incisive foramen. It supplies the nasal septum and the ends in the anterior part of the palate.

Posterolateral nasal nerves – Supply the posterior parts of the nasal cavity both the septum and the lateral walls. Palatine, Nasopalatine and Nasal nerves carry hitchhikers that stimulate secretion from the nasal and palatine glands, and taste fibres to the palate.

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