Download The Maxillary nerve HO

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.