Course and branches of the maxillary branch of the trigeminal nerve.
Hey everyone! This is Nicole from Kenhub, and welcome to our tutorial on the maxillary nerve. During this tutorial, we'll be using this lateral view of the cranium and brainstem to look at the maxillary nerve. We have, of course, our brainstem over here on the right with the trigeminal nerve and the optic nerve emerging and then passing through to the orbit and the eyeball.
In this tutorial, of course, although the focus is on the maxillary nerve, we're also going to talk about a few different structures associated with it starting first with the trigeminal nerve which is also known as the fifth cranial nerve followed by the trigeminal ganglion and finally the maxillary nerve which is often referred to as V2 as it's the second branch of the trigeminal nerve. With regards to the maxillary nerve, we'll talk about its many branches before finishing by talking about some clinical correlations but for now let's begin with the trigeminal nerve.
As I mentioned before, the trigeminal nerve is the fifth cranial nerve and is often referred to as CN V and, in addition to being the largest of the twelve cranial nerves, it's often considered to be the most complex. And as you can see after arising from its nucleus, it emerges from the midbrain at the junction of the pons and the middle cerebral peduncle as a large sensory root and a smaller motor root before merging with the trigeminal ganglion or the Gasseri ganglion – a knot-like mass of nerve cell bodies which we'll talk about a bit later on on the next slide. And the trigeminal nerve provides innervation for the sensation of the face, mucous membranes and some other structures of the head; the motor innervation of the muscles of mastication which includes the masseter muscle shown in green on the right as well as feedback for proprioception of the face and lower jaw.
The trigeminal ganglion or the Gasseri ganglion is a flattened sensory ganglion located within the middle cranial fossa in a depression called the trigeminal cave or Meckel's cave. And the ganglion gives rise to three branches of the trigeminal nerve: the ophthalmic nerve or V1 – a sensory nerve, the maxillary nerve or V2 – also a sensory nerve, and the mandibular nerve or V3 which carries both motor and sensory fibers. As the focus of today's tutorial is the maxillary nerve, we won't be discussing the ophthalmic and mandibular nerve. So if you're looking for more information on the ophthalmic nerve and the mandibular nerve, please make sure you check out our website for the tutorials on these nerves. But, for now, let's talk a little bit about the maxillary nerve.
So as we just mentioned, the maxillary nerve is the second branch of the trigeminal nerve and arises from the posterior surface of the trigeminal ganglion between the ophthalmic and the mandibular nerves which we can see on the image on the right. And the maxillary nerve can be divided into three parts each giving off a set of branches. The first part which we'll call the part before the maxillary nerve enters the foramen rotundum which is this little foramen just here and gives off this small branch here – the meningeal branch of the maxillary nerve.
The second part which we'll call the part located within the pterygopalatine fossa, the maxillary nerve gives off three branches – the zygomatic nerve, the posterior superior alveolar nerve, and the sensory root of the pterygopalatine ganglion. After entering the orbit which, although is a bit of a misnomer, we'll go ahead anyway and call it the infraorbital part, the maxillary nerve then becomes the infraorbital nerve traveling along the floor of the orbit and giving off two branches – the middle superior alveolar nerve and the anterior superior alveolar nerve. And after it gives off those two branches, the infraorbital nerve then finally exits the orbit through the infraorbital foramen. And we'll talk about all of these over the next few slides but for the moment, I just want to have a brief look at the overall innervation of the maxillary nerve and as you'll be able to see, the maxillary nerve receives sensation from the middle third of the face from the upper eyelid down to the upper lip.
So now that we've briefly outlined what we're going to talk about in this tutorial, let's begin with the meningeal branch of the first part of the maxillary nerve. So as we mentioned, the first part of the maxillary nerve is the part that contains the first branch to come off the maxillary nerve which as we mentioned before is the branch called the meningeal branch. And as you can see, this branch arises before the maxillary nerve enters the foramen rotundum which we pointed out earlier and it contributes to the innervation of the dura mater.
The second part of the maxillary nerve is the part that is found within the pterygopalatine fossa which are marked off here with some lines, and the first branch that the maxillary nerve gives off in the pterygopalatine fossa is the zygomatic nerve. And as you can see, the zygomatic nerve highlighted in green enters the orbit through the infraorbital canal and then travels near the base of the orbit's lateral wall where it divides into two branches – the zygomaticotemporal nerve and the zygomaticofacial nerve. And as you can probably guess with regards to their innervation, the zygomatic nerve and its branches carry sensory fibers from the skin over the temporal bone and the skin over the zygomatic bone.
And one miscellaneous structure I'm going to throw in just here – and you might have noticed this nerve here – the communicating branch of the lacrimal nerve with the zygomatic nerve – and wondered what it was. Well, this nerve is a nerve that does exactly what it says it does, that is, communicates the zygomatic nerve with the lacrimal nerve which is a branch of the ophthalmic nerve. And now we're here back again at our image of the communicating branch of the lacrimal nerve and in terms of its relevance, this nerve is quite important as it allows parasympathetic fibers to be transferred from the zygomatic nerve to the lacrimal nerve.
So I'm moving back to the branches that arise from the maxillary nerve within the pterygopalatine fossa, let's now have a look at the posterior superior alveolar nerve. And as you can see, the posterior superior alveolar nerve descends within the maxilla through the pterygomaxillary fissure which is deep to the pterygopalatine fossa and therefore can't be seen in this image. And this nerve divides into many branches forming a plexus called the superior dental plexus that we'll see later on. And as for its innervation, the posterior superior alveolar nerve carries sensory fibers from the mucosa of the posterior maxillary sinus, the maxillary that is the upper molar teeth and they're highlighted in green in this image, and the posterior superior alveolar nerve also supplies the surrounding gingivae which is of course the gums and that would cover the maxillary bone within the mouth like in this image of a molar tooth.
Now let's move on to have a look at the third and final branch of the maxillary nerve within the pterygopalatine fossa – the sensory root of the pterygopalatine ganglion. And as the name suggests, the sensory root of the pterygopalatine ganglion carries sensory fibers from the pterygopalatine ganglion which we'll talk a little bit more about on the next slide.
The pterygopalatine ganglion is important to mention because it's one of the four major parasympathetic ganglia found within the head and neck. The others being the submandibular ganglion, the otic ganglion and the ciliary ganglion. With regards to the maxillary nerve, the pterygopalatine ganglion is mainly a communicating station between the maxillary nerve and three of its own branches – the nasopalatine nerve, the palatine nerves, and the pharyngeal nerve – and we'll talk a little bit about each of these over the following slides.
The first branch that stems from the pterygopalatine ganglion is known as the nasopalatine nerve which we can see in this image in the breakout. And as you can see in this image of the nasopalatine with some of its branches reflected onto the medial wall of the nasal cavity, the nasopalatine nerve is the longest and largest branch of the pterygopalatine ganglion. And just staying with this image of the nasopalatine nerve, we can see that the nasopalatine nerve leaves the pterygopalatine fossa and enters the nasal cavity through the sphenopalatine foramen which is just here. And the nasopalatine nerve carries sensory fibers from the lower part of the nasal cavity which in this image is this section just here, the anterior aspect of the hard palate, and the nasal septum.
The next branch arising from the pterygopalatine ganglion are two nerves which are together known as the palatine nerves, and in this image you can see them coming off inferiorly from the ganglion just here. And these two nerves are known as the greater palatine nerve and the lesser palatine nerve emerging from the lesser palatine foramen. With regards to their innervation, we can see that the greater palatine nerve which we can see highlighted in green on this image of the lateral wall of the nasal cavity and emerging from the greater palatine foramen carries sensory fibers to the gingivae and the hard palate while the lesser palatine nerve carries fibers from the soft palate, the uvula and the tonsils. And in this image, we're looking at the palatine tonsils.
The final branch arising from the pterygopalatine ganglion is the pharyngeal nerve and as you can see in the breakout, the pharyngeal nerve branches off the posterior part of the pterygopalatine ganglion. And the pharyngeal branch carries sensory fibers from the mucosa of the nasopharynx which we can see here highlighted in green.
So now that we've looked at the maxillary nerve and its branches inside the pterygopalatine fossa, let's move on and look at the maxillary nerve after it exits this fossa which is the third part of the nerve. And when the maxillary nerve exits the pterygopalatine fossa, it's then known as the infraorbital nerve. The infraorbital nerve along with the infraorbital artery enters a depression in the floor of the orbit which is called the infraorbital groove and which is around about here until it reaches a canal in the floor of the orbit called the infraorbital canal which is around about here. And as the infraorbital nerve travels along the infraorbital canal, it gives off two further branches – the middle superior alveolar nerve and the anterior superior alveolar nerve. And we'll have a look at these and their innervation over the next few slides but first I want to talk a little bit about the continuation of the infraorbital nerve.
So coming back to our image of the infraorbital nerve, we can see that after giving off these two branches, the infraorbital nerve then continues along the floor of the orbit to finally exit through the infraorbital foramen which is this large foramen just here on the maxilla. And once it's through the infraorbital foramen, the infraorbital nerve becomes superficial carrying sensory fibers from the lower eyelid, the side of the nose and the anterior part of the cheek and upper lip.
So I just want to go back a little bit and have a little bit of a chat about the branches of the infraorbital nerve. And the first branch arising from the infraorbital nerve on the floor of the orbit as we mentioned earlier is the middle superior alveolar nerve. And the middle superior alveolar nerve is a little bit interesting because although on this image, there are two nerves that make up the middle superior alveolar nerve coming off the infraorbital nerve, the middle superior alveolar nerve is actually quite variable and can consist of one, two or three nerves or it can be entirely absent. And the middle superior alveolar nerve carries sensory fibers from the mucosa of the maxillary sinus which is highlighted in green and the maxillary premolars which are the teeth highlighted in green just here.
The second branch that arises from the infraorbital nerve is the anterior superior alveolar nerve and as you can see on this image, the anterior superior alveolar nerve arises from the infraorbital nerve just before it exits the orbit via the infraorbital foramen. And if you look at our breakout just here, you can see it coming off the infraorbital nerve just here and then descending within the maxilla to emerge deep to the maxilla as opposed to the infraorbital nerve which is running superficial to the maxilla. And the anterior superior alveolar nerve carries sensory fibers from the maxillary canine teeth and the maxillary incisor teeth.
So I mentioned the superior dental plexus a little bit earlier in the tutorial and now I'd like to talk about it a little bit as it's an important part of the innervation of the upper jaw. So as you can see illustrated in this image, a superior dental plexus is created from the nerves of the posterior superior alveolar nerve, the middle superior alveolar nerve and the anterior superior alveolar nerve. And this plexus is an important aspect of the carriage of sensory fibers from the upper jaw. The superior dental plexus also gives off the superior dental branches which are highlighted in green in this image, and they carry sensory fibers from the roots of the teeth of the upper jaw.
So now that we've reached the end of our tutorial on the maxillary nerve, let's summarize everything that we covered. The maxillary nerve or V2 is the second of the three branches of the trigeminal nerve and has a long course that can be divided into three sections. The first part which is the part before it enters the foramen rotundum where it gives off the meningeal branch of the maxillary nerve; within the pterygopalatine fossa, it gives off three branches – the zygomatic nerve, the posterior superior alveolar nerve and the sensory root of the pterygopalatine ganglion; and after the maxillary nerve exits the pterygopalatine fossa, the maxillary nerve is then given the name the infraorbital nerve and the infraorbital nerve gives off two branches – the middle superior alveolar nerve and the anterior superior alveolar nerve.
To finish off the tutorial, let's finally go over some clinical notes related to the maxillary nerve and its branches. And the main clinical note about the maxillary nerve I want to talk about today is anesthesia of the upper jaw and its associated structures such as the teeth known as a maxillary nerve block. So in surgeries involving the maxilla, nose and the mouth, a block of the maxillary nerve supply is normally achieved by injecting local anesthetic in close proximity to the maxillary nerve usually in the pterygopalatine fossa. If smaller areas of anesthesia are needed then more specific nerve blocks are carried out and an example of this is a posterior superior alveolar nerve block which will anesthetize the maxillary molar teeth for procedures such as a root canal or the surgical removal of a molar.
Another interesting clinical note that I'd like to talk about is the orbital blowout fracture which is a fairly significant fracture to the floor or the medial wall of the orbit usually involving a blunt object. And in this case, the most likely part of the maxillary nerve to receive damage is the infraorbital nerve due to its location at the floor of the orbit resulting in loss of sensation in the upper jaw and in the cheeks.
And that's the end of our tutorial on the maxillary nerve. Thanks for watching.
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