(4.30)

Now that we're oriented, let's look at the maxillary nerve. As we've seen, the maxillary nerve runs forwards from the trigeminal ganglion, and enters the foramen rotundum, which is here.

Here's the foramen rotundum in the dry bone. We'll go round to the outside to see where it emerges. Here it is, well hidden in the pterygo-maxillary fissure. The foramen rotundum goes out of sight as we go round to a lateral view of the pterygo-maxillary fisure. Now we'll return to the dissection.

Here's the maxillary nerve, running forwards across the pterygo-maxillary fissure. As it approaches the maxilla it divides into branches. The continuing trunk of the nerve is known as the infra-orbital nerve. We'll follow it first.

The infra-orbital nerve runs forward into a bony tunnel in the floor of the orbit. It emerges again here, at the infra-orbital foramen. The infra-orbital nerve divides into palpebral, labial and nasal branches. These supply the lower eyelid, part of the nose and cheek, and the upper lip.

The branches of the maxillary nerve supply the upper teeth, the nasal cavity and palate, and the upper part of the cheek. Most of them run through tunnels in the bone. Because of this, and because they're small, they're hard to show in a dissection. To indicate where they run, we'll add lines to the picture.

The upper teeth are supplied by the superior alveolar nerves, posterior and anterior, which together form a loop.

The posterior superior alveolar nerves (in this case there are two) branch off behind the maxilla, and run down to enter tunnels in the maxilla here. The anterior superior alveolar nerve arises from the infra-orbital nerve within its tunnel, and runs downwards and forwards within the bone.

The superior alveolar nerves, anterior, and posterior, form a loop within the maxilla. From this loop dental and gingival branches arise that supply the upper teeth, and the upper gums.

The maxillary nerve also gives off palatine and nasopalatine branches that supply the palate, and parts of the nasal cavity. To see where these go we'll look at a skull that's been divided in the mid-line. The opening that's illuminated is the sphenopalatine foramen, which opens into the pterygo-maxillary fissure. The maxillary nerve enters the fissure from behind, here.

Two palatine nerves, the greater and lesser, arise from the maxillary nerve and run down through a bony tunnel that's been partly opened here. The palatine nerves emerge here, through the palatine foramen. The palatine nerves provide sensation to the palate from here to here.

In addition the greater palatine nerve has nasal branches. Together with nasal branches from the trunk of the maxillary nerve, these supply this part of the lining of the nasal cavity.

The nasopalatine nerve passes through the sphenopalatine foramen, round the front of the sphenoid sinus, and onto the nasal septum. The nasopalatine nerve supplies the nasal septum, then passes through the incisive foramen in the maxilla, to supply the anterior part of the hard palate.

Last of all, the maxillary nerve gives off a zygomatic branch. This divides into the zygomatico-facial and zygomatico-temporal nerves. These pass through the zygomatic bone, emerging here, to supply this part of the cheek.