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4.4.4 Muscles of mastication: pterygoid muscles

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(2.42)

We’ll move on now, to look at those four muscles. They’re known collectively as the muscles of mastication.

The muscles that close the jaw are much more powerful than the ones that open it. Closing is produced by three large muscles on each side, the medial pterygoid, the temporalis, and the masseter. Opening is produced by the lateral pterygoid muscle, which we’ll see in a moment, and by some smaller muscles below the mandible that we’ll add to the picture later in this section.

Of the four muscles that we’ll look at now, we’ll start with the one that’s hardest to see, the lateral pterygoid. To get a look a look at it, we need to remove the coronoid process, and the zygomatic arch. This lets us see the infratemporal fossa, and behind it, the lateral pterygoid plate.

Here’s the lateral pterygoid muscle. It’s quite small. The lateral pterygoid muscle arises partly from the underside of the greater wing of the sphenoid, and partly from the lateral aspect of the lateral pterygoid plate.

The fibers of the lateral pterygoid muscle run backward and a little laterally. We’ll go round to a medial view to see where they go. The main insertion of the lateral pterygoid is into this hollow on the front of the condylar process.

The lateral pterygoid also inserts onto the capsule of the temporomandibular joint, and into the front edge of the articular disk. These windows in the capsule were made artificially, as in the shot that we saw previously.

Now that we’ve seen the lateral pterygoid, we’ll add the medial pterygoid muscle to the picture. The medial pterygoid muscle is larger than the lateral pterygoid, and runs in a quite different direction. The medial pterygoid muscle arises from both the pterygoid plates: the medial aspect ...

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(2.42)

We’ll move on now, to look at those four muscles. They’re known collectively as the muscles of mastication.

The muscles that close the jaw are much more powerful than the ones that open it. Closing is produced by three large muscles on each side, the medial pterygoid, the temporalis, and the masseter. Opening is produced by the lateral pterygoid muscle, which we’ll see in a moment, and by some smaller muscles below the mandible that we’ll add to the picture later in this section.

Of the four muscles that we’ll look at now, we’ll start with the one that’s hardest to see, the lateral pterygoid. To get a look a look at it, we need to remove the coronoid process, and the zygomatic arch. This lets us see the infratemporal fossa, and behind it, the lateral pterygoid plate.

Here’s the lateral pterygoid muscle. It’s quite small. The lateral pterygoid muscle arises partly from the underside of the greater wing of the sphenoid, and partly from the lateral aspect of the lateral pterygoid plate.

The fibers of the lateral pterygoid muscle run backward and a little laterally. We’ll go round to a medial view to see where they go. The main insertion of the lateral pterygoid is into this hollow on the front of the condylar process.

The lateral pterygoid also inserts onto the capsule of the temporomandibular joint, and into the front edge of the articular disk. These windows in the capsule were made artificially, as in the shot that we saw previously.

Now that we’ve seen the lateral pterygoid, we’ll add the medial pterygoid muscle to the picture. The medial pterygoid muscle is larger than the lateral pterygoid, and runs in a quite different direction. The medial pterygoid muscle arises from both the pterygoid plates: the medial aspect of the lateral one, and the lateral aspect of the medial one, also from this corner of the maxilla, the tuber.

The fibers of the medial pterygoid muscle run downwards, backwards and laterally. They insert here along the inner aspect of the angle of the mandible.

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