Muscle Anatomy: Masseter Muscle

Questions and Answers

What are the two parts to the Masseter Muscle?

Superficial and deep

Which muscle group does the Masseter muscle belong to?

Muscle of Mastication

What is the origin of the Masseter muscle?

Zygomatic process of the maxilla and zygomatic arch

Where is the insertion point of the Masseter?

The external surface of the ramus and angle of the mandible, coronoid process of the mandible Signup and view all the answers

What is the action of the Masseter muscle?

The Masseter muscle elevates the mandible. Specifically, the superficial aids in mandible protrusion while deep assists in mandible retraction. Signup and view all the answers

What is the innervation of the Masseter muscle?

Nerve to the masseter from mandibular division of the trigeminal nerve Signup and view all the answers

Describe the Masseter muscle with respect to origin, insertion, action, and innervation.

The Masseter muscle is divided into two parts; superficial and deep. It originates at the zygomatic arch and inserts at the ramus of the mandible, allowing the mandible to elevate. Signup and view all the answers

What group does the Temporalis muscle belong to?

Muscle of mastication Signup and view all the answers

Name the three parts of the Temporalis muscle.

Anterior, middle, and posterior Signup and view all the answers

What is the origin of the Temporalis muscle?

The temporal fossa Signup and view all the answers

Where does the Temporalis muscle insert?

Coronoid process of the mandible, anterior surface of the ramus of the mandible Signup and view all the answers

What is the action of the Temporalis muscle?

Elevates and retracts the mandible Signup and view all the answers

What is the innervation of the Temporalis muscle?

Deep temporal nerve of the mandibular division of the trigeminal nerve Signup and view all the answers

Describe the Temporalis muscle with respect to origin, insertion, action, and innervation.

The Temporalis muscle is divided into three parts; anterior, middle, and posterior. Its origin is at the temporal fossa whilst it inserts at the coronoid process of the mandible. This muscle allows elevation and retraction of the mandible and the deep temporal nerve of the mandibular division of the trigeminal nerve innervates the muscle. Signup and view all the answers

What two parts can the Pterygoid muscle be divided into?

Medial (internal) and lateral (external) Signup and view all the answers

What muscle group does the medial Pterygoid muscle belong to?

Muscle of mastication Signup and view all the answers

Where is the origin of the medial Pterygoid muscle?

Lateral pterygoid plate and fossa of the sphenoid Signup and view all the answers

Where is the insertion point of the medial Pterygoid muscle?

Internal surfaces of the angle and ramus of the mandible Signup and view all the answers

What is the action of the medial Pterygoid muscle?

<ul> <li>Elevates the mandible with the temporalis and masseter muscles</li> <li>Protrudes the mandible with the lateral pterygoid muscle</li> <li>Unilateral contracting moves jaw laterally (opposite side)</li> </ul> Signup and view all the answers

What nerves innervate the medial Pterygoid muscle?

Medial pterygoid nerve of the mandibular division of the trigeminal nerve Signup and view all the answers

Describe the medial Pterygoid muscle with respect to origin, insertion, action, and innervation.

The medial Pterygoid muscle originates from the lateral pterygoid plate of the sphenoid and inserts at the internal surface of the angle and ramus of the mandible. This muscle acts to elevate the mandible as well as protrude it, and if contracted unilaterally, can move the jaw laterally (opposite side). The medial pterygoid nerve of the mandibular division of the trigeminal nerve innervates the medial Pterygoid muscle. Signup and view all the answers

What is the origin of the lateral Pterygoid muscle?

The greater wing of the sphenoid as well as the external surface of the lateral pterygoid plate of the sphenoid Signup and view all the answers

Where is the insertion point of the lateral Pterygoid muscle?

Articular disc of the temporomandibular joint and the pterygoid fovea of mandible, which is located at the neck of the condylar process Signup and view all the answers

What is the action of the lateral Pterygoid muscle?

Bilateral contraction protrudes mandible. Unilateral contraction moves mandible laterally toward the opposite side (grinding). Co-activated with jaw closing muscles. Signup and view all the answers

What nerves innervate the lateral Pterygoid muscle?

The anterior trunk of the mandibular division of the trigeminal nerve Signup and view all the answers

Study Notes

Masseter Muscle

Composed of two parts: superficial and deep.
Belongs to muscle group responsible for mastication.
Originates from the zygomatic process of the maxilla and the zygomatic arch.
Inserts on the external surface of the ramus and angle, as well as the coronoid process of the mandible.
Functions to elevate the mandible; superficial part aids in protrusion, while the deep part assists in retraction.
Innervated by a nerve from the mandibular division of the trigeminal nerve.

Temporalis Muscle

Comprised of three parts: anterior, middle, and posterior.
Part of the muscle group responsible for mastication.
Originates from the temporal fossa.
Inserts at the coronoid process and anterior surface of the ramus of the mandible.
Actions include elevating and retracting the mandible.
Innervated by the deep temporal nerve from the mandibular division of the trigeminal nerve.

Medial Pterygoid Muscle

Divided into medial (internal) and lateral (external) parts.
Another member of the muscle group for mastication.
Originates from the lateral pterygoid plate and fossa of the sphenoid bone.
Inserts at the internal surfaces of the angle and ramus of the mandible.
Elevates the mandible, protrudes it with lateral pterygoid muscle, and can move the jaw laterally when contracted unilaterally.
Innervated by the medial pterygoid nerve from the mandibular division of the trigeminal nerve.

Lateral Pterygoid Muscle

Originates from the greater wing of the sphenoid and the external surface of the lateral pterygoid plate.
Inserts at the articular disc of the temporomandibular joint and the pterygoid fovea located at the neck of the condylar process of the mandible.
Functions to protrude the mandible through bilateral contraction and moves the mandible laterally during unilateral contraction, aiding in grinding.
Co-activated with jaw-closing muscles during certain movements.
Innervated by the anterior trunk of the mandibular division of the trigeminal nerve.

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Test your knowledge on the Masseter muscle with these flashcards. Explore its anatomy, origin, insertion points, and classification. Perfect for students studying human anatomy or anyone interested in muscle functions.