The primary muscles of mastication are located around the temporomandibular joints, filling various skull regions. It is crucial to know the anatomical locations of these muscles to understand how they act and which function each muscle provides. And it is even more important to fully understand the sites where these muscles are attached to bony structures. 

• The temporal muscle fills the temporal fossa (Read more!).
• The masseter is located within the cheeks and lies on the external surface of the mandibular ramus (the mandible is reviewed in the next slide).
• The lateral and medial pterygoid muscles are positioned in the infratemporal fossa (Read more!).

Temporal fossa

The temporal fossa is a depressed area located on either side of the skull in the temporal region. It is found superior to the zygomatic arch and the infratemporal fossa and inferior to the superior temporal line of the parietal bone. The bones and structures forming the walls of the temporal fossa are as follows:

• Medial wall - temporal surface of the squamous part of the frontal bone, external surface of the parietal bone, temporal surface of the greater wing of the sphenoid bone, and the temporal surface of the squamous part of the temporal bone;
• Anterior wall - temporal surface of the squamous part of the frontal bone, temporal surface of the zygomatic bone;
• Inferior wall - space that connects with the infratemporal fossa;
• Lateral wall - zygomatic arch (formed by the zygomatic process of the temporal bone and temporal process of the zygomatic bone).

Infratemporal fossa

The infratemporal fossa is an irregularly shaped space situated at the base of the skull below the temporal fossa and deep to the ramus of the mandible. The walls of the infratemporal fossa are formed by the following bones and soft tissue:

• Superior wall (roof) - infratemporal surface of the greater wing of the sphenoid; 
• Inferior wall (floor) - formed by the medial pterygoid muscle;
• Lateral wall - condylar process and medial aspect of the mandibular ramus, medial aspect of the zygomatic arch;
• Medial wall - lateral pterygoid plate of the sphenoid bone;
• Posterior wall - formed by the carotid sheath;
• Anterior wall - infratemporal surface of the maxilla.