Re: #8 four muscles of mastication- origin, insertion, action | anatomy

Peer response 

 

Research 

What are muscles of mastication? Muscles of mastication are the muscles that are used when you chew on something. It is the process of moving the mandible up and down or side to side. Based on my research the four muscles of mastication are the Masseter Muscle, Temporal Muscle, Medial Pterygoid, and Lateral Pterygoid (Saladin, 2020, p. 238).  

Masseter Muscle: The Masseter is the most dominant of the four muscles of mastication. This muscle divides into two parts a superficial head and a deep head (Saladin, 2020, p. 238). The Masseter is located at the very back of your jaw line and goes up just below the cheek bone. The exact insertion would be at the angle of the mandible and superior surface of the ramus (Saladin, 2020, p. 238). The exact origin of the superficial head is at the lower border of the zygomatic bone. The exact location of the deep head is at the lower border of the zygomatic arch (Saladin, 2020, p. 238). The action of the masseter is to elevate and lower the mandible (Saladin, 2020, p. 238).  

Temporal Muscle: This muscle is a fan shaped muscle; it is not divided into two parts like the others. The exact origin of this muscle is Temporal Fossa (Saladin, 2020, p. 238). The exact insertion would be in the coronoid process of the mandible (Saladin, 2020, p. 238). The action of the Temporal Muscle is the elevation and retraction of the mandible which closes the mouth (Saladin, 2020, p. 238). 

Medial Pterygoid: This muscle also divides into two parts. The exact origin of the superficial head of the Medial Pterygoid is Maxillary tuberosity and pyramidal process of bone (kind of where your wisdom teeth are located) (Saladin, 2020, p. 238). The exact origin of the deep head is the medial surface of lateral pterygoid (Saladin, 2020, p. 238). They both insert into the medial surface of the ramus (Saladin, 2020, p. 238). The action of this muscle is the control over the side-to-side movement of the jaw (Saladin, 2020, p. 238). 

Lateral Pterygoid: This muscle has two parts as well. The exact origin of the superficial head would be at the Greater wing of sphenoid bone (Saladin, 2020, p. 238). The deep head is located on the lateral surface of the lateral pterygoid plate (Saladin, 2020, p. 238). The insertion of the lateral pterygoid is at the anterior aspect of the mandibular condyle (Saladin, 2020, p. 238). The action of this muscle is that it depresses the mandible (Saladin, 2020, p. 238).  

Critical Thinking 

Muscles of mastication are muscles that work together to open and close your mouth. All the movements are the movements of the mandible to chew which is called mastication. You may be wondering what the mandible is? The mandible is your lower jawbone and is the largest bone in the human skull. The maxilla (which is the upper jaw) does not move, therefore the mandible is the only one part that moves. All the four muscles of mastication are connected to the mandible to make it move up and down and side to side. 

References 

Saladin, K. (2020). Anatomy & physiology: The unit of form and function (9th ed.). McGraw Hill Education. 

 

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