Now that we’ve looked at the teeth we’ll move on to look at the glands that produce saliva, the salivary glands. There are three salivary glands, the parotid gland on the side of the face, the submandibular gland beneath the body of the mandible, and the sublingual gland in the floor of the mouth. We’ll look at the parotid gland first.
Part of the parotid gland lies superficially in the posterior part of the cheek, part of it lies deep in the space between the ramus of the mandible and the sternocleidomastoid muscle. We’ll look at the deep part first.
To look at the deep part of the parotid gland we’ll start with a dissection in which the whole of the gland has been removed. This is a good opportunity to see all in one place a number of structures that we’ve learned about separately. Let’s take a good look round.
Here’s the posterior border of the ramus of the mandible, here’s the zygomatic arch, here’s the external auditory meatus, here’s the mastoid process. Here’s the sternocleidomastoid muscle, here’s the masseter muscle. Here’s the space that’s occupied by the deep part of the parotid gland.
Here’s the posterior belly of the digastric muscle, lying deep to the sternocleidomastoid. Here’s the styloid process, and the stylohyoid muscle. Here, emerging behind the styloid process, is the trunk of an important nerve, the facial nerve.
The facial nerve, which provides the motor innervation to all the muscles of facial expression, has an important relationship to the parotid gland: it runs right through it, dividing into several branches as it does so.
Now that we’ve seen the space that’s occupied by the deep part of the parotid gland, we’ll add the deep part of the gland to the picture. Here’s the cut surface of the parotid gland. Again, here are the sternocleidomastoid muscle, the masseter, and the ramus of the mandible. Before we add the superficial part of the parotid gland, we’ll add the facial nerve to the picture.
Here’s the trunk of the facial nerve, entering the parotid gland from behind. The branches of the facial nerve fan out upwards, forwards and downwards. We’ll take a more complete look at the facial nerve in the next tape in the series. Here, we’re concerned only with its relationship to the parotid gland.
Now we’ll add the superficial part of the gland to the picture. Here it is. The superficial part of the parotid gland covers the posterior part of the masseter muscle. Its extent varies. It usually extends up as far as the zygomatic arch, and down to the angle of the mandible. It can also overlap the anterior border of the sternocleidomastoid muscle.
The saliva that’s secreted by the parotid gland passes into the parotid duct, which emerges from the anterior border of the gland, and passes forward around the anterior border of the masseter. The parotid duct enters the oral cavity by passing through the buccinator muscle and through the underlying mucous membrane, at about the level of the second upper molar tooth.