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The temporal fossa and temporomandibular joint (TMJ)

Part 1 of 2
Published on June 30, 2024   17 min

A selection of talks on Physiology & Anatomy

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0:00
My name is George Dias. I am a professor of anatomy in the Department of Anatomy at the University of Otago. I'm going to talk to you about regions of the head region. The temporal fossa and the temporomandibular joint.
0:19
Let's start with the temporal fossa. The first diagram shows the skull with the different cranial bones that have been given different colors. In the second diagram, we have included the temporalis muscle onto the skull as well as the deep part of the parotid gland is also there just behind the ramus of the mandible. Also, you can see the temporal fascia that covers the temporalis muscle has been removed but the edges of the fascia can be seen on the second diagram. The fossa is a space; therefore, the temporal fossa is a space. First, we will look at the boundaries of this space. Superiorly, the temporal fossa is bounded by the superior temporal line as is indicated in the first diagram. The superior temporal line is a bony ridge that is caused by the attachment of the temporal fascia. In fact, below the superior temporal line there's another line the inferior temporal line. The inferior temporal line demarcates the peripheral margin of the attachment of the temporalis muscle. We go back to the boundaries. The superior boundary is the superior temporal line. You can see on the lateral surface of the skull, the cranium. The inferior boundary is the zygomatic arch as we are demonstrating in the first image. Now, we know the zygomatic arch is formed by two bones. We have the zygomatic process of the temporal bone and the temporal process of the zygomatic bone from this arch. That's the inferior boundary of the temporal fossa. The lateral wall of the temporal fossa is the fascia that covers the temporalis muscle, the dense fibrous tissue sheet. The temporal fascia is attached, as we said, to the superior temporal line superiorly. Inferiorly, it's attached to the zygomatic arch that forms the lateral wall of the temporal fossa. The medial wall of the temporal fossa is part of the lateral aspect of the cranial vault. There are a number of cranial bones contributing to the medial wall of the temporal fossa, that part of the lateral surface of the vault of the skull. Now, what are these bones? As shown in the first diagram, part of the purple bone is the parietal bone. Then the green bone, the squamous part of the temporal bone. The flat part of the temporal bone. For the anteriorly, you have the frontal bone contributing to the temporal fossa. For the down, there is another bone, the blue-colored bone, which is the greater wing of the sphenoid. The sphenoid bone contributes to the wall of the cranial vault, that is the greater wing of the sphenoid, also therefore, contributes to the medial wall of the temporal fossa. When you discuss the medial wall of the temporal fossa, you also must note the region of the pterion. The pterion is a region where four cranial bones come together. The four cranial bones are the parietal bone, the frontal bone, the temporal squamous part of the temporal bone, and the greater wing of the sphenoid. Those four bones are placed in this area called the pterion. In this area, the skull is relatively thin and also it has clinical implications. There is an important artery. The branch of the middle meningeal artery runs deep into the pterion. We'll not go into the details about the clinical implications at this point. The anterior wall of the temporal fossa is formed by the frontal bone. The part that forms the anterior wall is the zygomatic process of the frontal bone. Then, we have the zygomatic bone forming the anterior wall. On the medial aspect, you find the maxilla. Those are the bones that form the anterior wall of the temporal fossa. Now that we talked about boundaries and the different walls of the temporal fossa, what do you find within this space? The structure that is found in the temporal fossa is the temporalis muscle. Large, fan-shaped muscle, which is an important muscle, is one of the muscles of mastication. It's a powerful elevator of the mandible so it can retract the mandible. We'll talk about the mandibular movements in a little while. The temporalis muscle is found in the temporal fossa.

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The temporal fossa and temporomandibular joint (TMJ)

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