Anatomy and Physiology of Children and Adolescents - M. R. Sapin 2007

Musculoskeletal System
Muscular System
Muscles of the Head - Masticatory Muscles

The masticatory Muscles are formed by four pairs of short, thick, powerful muscles that originate on the BONES OF THE Skull base and attach to its only movable bone—the Mandible. Two of these muscles are superficial (the temporalis and the masseter), while the other two (the pterygoids) are located deep, medially to the mandibular ramus within the infratemporal fossa.

The temporalis Muscle, wide at the top and narrow at the bottom, originates on the lateral surface of the neurocranium and inserts into the coronoid process of the mandible. It acts primarily on the anterior Teeth (incisors and canines), which is why it is often referred to as the biting muscle. The posterior fibers of this muscle pull the mandible backward.

The masseter muscle originates on the zygomatic arch, runs inferiorly and posteriorly, and inserts into the outer surface of the mandibular angle. This muscle elevates the angle of the mandible and plays an active role in the mastication process.

The medial pterygoid muscle originates in the pterygoid fossa of the Sphenoid bone, extends downward, and inserts into the corresponding tuberosity on the Medial surface of the mandibular angle. Like the masseter, this muscle also elevates the mandibular angle and participates in chewing.

The lateral pterygoid muscle is located in the infratemporal fossa and features a different topography. It originates on the posterior surface of the Maxilla's tuberosity, runs posteriorly, and inserts into the condylar process of the mandible. Bilateral contraction of these muscles protrudes the mandible forward, whereas unilateral contraction shifts it to the opposite side.

The capacity of the mandible to perform A wide variety of movements within the temporomandibular joints makes the entire human masticatory apparatus truly versatile.

All masticatory muscles possess their own fascias. A superficial fascia covers the masseter muscle and is fused with the capsule of the Cytology/practical/97.html">Parotid salivary gland; consequently, it is referred to in scientific literature as the parotideo-masseteric fascia. Externally, the temporalis muscle is also covered by a dense temporal fascia, which originates on the lateral surface of the neurocranium just above the Water/144.html">Origin of the muscle itself and attaches to the zygomatic arch.