(4.32)

To get a view of the pharynx from the side, we’ll start with a dissection in which all the neck muscles are present. The only parts of the pharynx we can see are here, and here.

To get a better view we’ll remove the sternocleidomastoid muscle. We’ll also remove all the underlying nerves and blood vessels. Here, just in front of the vertebral column, are the longus capitis and longus cervicis muscles.

Here, below them, are the scalene muscles. Here’s the lower half of the pharynx. The pharynx lies just in front of the longus muscles. To see the whole of the pharynx, from behind, we’ll remove the vertebral column and all the neck muscles.

Here’s the pharynx. The pharynx extends from the base of the occiput, to the level of the top of the clavicle. The upper part of the pharynx is partly hidden by the digastric muscle, which we’ll remove.

The upper part of the pharynx is hidden also by the styloid process, and the three muscles that descend from it, stylohyoid which we’ll remove, and two other slender muscles, which we’ll meet shortly, styloglossus, and stylopharyngeus. For now, we’ll remove them too, along with the styloid process.

Now we can finally get a clear view of the whole of the pharynx. Here above the pharynx is the base of the occiput. These are the occipital condyles. Here’s the medial pterygoid muscle, sloping downwards from the medial pterygoid plate, which is here.

The wall of the pharynx is formed by an almost continuous layer of muscle, lined by mucous membrane. The muscular layer consists of three sheets of muscle, the constrictor muscles, superior, middle, and inferior. These overlap behind, the one above inside the one below. Here’s the inferior constrictor, here’s the middle constrictor, here’s the superior constrictor.

The superior constrictor is very thin. Its fibers arise from the lower part of the medial pterygoid plate, the hamulus, and the pterygo-mandibular band, and also from the side of the tongue.

The superior constrictor has a free upper border. Above this the wall of the pharynx is formed by this layer of fascia, the pharyngo-basilar fascia. The highest fibers of the superior constrictor insert on the base of the occipital bone. The remaining fibers meet in the midline with the fibers from the opposite side, extending down inside the middle constrictor.

Here’s the middle constrictor. It’s a thicker muscle. The middle constrictor arises from the lesser horn, and the greater horn of the hyoid bone. Here’s the tip of the greater horn of the hyoid bone, heres the edge of the lateral thyrohyoid ligament. The fibers of the middle constrictor fan out, meeting with those of the opposite side, from here, down to here inside the inferior constrictor.

Here’s the upper border of the inferior constrictor. It’s thicker again than the middle constrictor. The inferior constrictor arises from just behind the oblique line on the thyroid cartilage, and also from the side of the cricoid cartilage. Its fibers fan out, meeting with the fibers from the other side all the way from here, down to here.

The lower end of the inferior constrictor muscle is continuous with the muscular coat of the esophaus. The lowest part of the inferior constrictor, which is functionally separate from the rest of the muscle, is referred to as the cricopharyngeus muscle. It forms a sphincter round the upper end of the esophagus.