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Mastication
Muscles of Mastication
Question | Answer |
---|---|
Name the four muscles of mastication: | Masseter, Temporalis, Medial Pterygoid, Lateral Pterygoid |
Name the 8 bony landmarks for the muscles of mastication: | Temporal fossa, coronoid process, ramus, zygomatic arch, sphenoid bone, palatine bone, maxillary tuberosity, condyle |
What part of the sphenoid bone is a bony landmark for the muscles of mastication? | Greater wing (medial and lateral pterygoid plate) |
What nerve are the muscles of mastication innervated by? | V3 of the trigeminal nerve |
What branch are the muscles embriologically derived from? | 1st branchial arch |
Which muscle(s) are involved with elevation of the mandible? | Masseter, temporalis, medial pterygoid |
Which muscle(s) are involved with protrusion or depression? | Lateral pterygoid |
Which muscle arises from two heads? | Masseter |
What are the two heads of the masseter muscle called? | Deep head and superficial head of the masseter |
What is the origin and insertion of the superficial head of the masseter? | Origin- Posterior 1/3 and medial surface of the zygomatic arch Insertion- Lateral surface of ramus and angle of mandible |
What is the origin and insertion of the deep head of the masseter? | Origin- Zygomatic process of the maxilla and anterior 2/3 of the lower border of the zygomatic arch Insertion- Lateral surface of ramus and angle of mandible |
Action of the masseter muscle: | Elevate the angle of the mandible |
Action of the temporalis muscle: | Elevates the coronoid process and retracts the jaw |
What is the origin and insertion of the temporalis muscle? | Origin- temporal fossa of parietal and frontal bones; below the superior temporal line and from temporal fascia Insertion- coronoid process and anterior border of the ramus |
Action of the internal (medial) pterygoid muscle: | Elevate the angle of the jaw and sideways movement |
What is the origin and insertion of the internal (medial) pterygoid muscle? | Origin- medial surface of lateral pterygoid plate and tuberosity of maxillary bone. Insertion- medial surface of ramus and angle of mandible |
Which muscle involves drawing the condyles of the mandible forward resulting in the TMJ opening? | External (lateral) pterygoid muscle |
What are the two groups of muscles that have an influence on the movement of the mandible? | Suprahyoid muscles and muscles of mastication |
Which muscles are considered accessory muscles to the mandible? | Geniohyoid, mylohyoid, digastric |
Which group of muscles assist the lateral pterygoid muscles in depressing the mandible? | Suprahyoid muscles |
Which group of muscles assist the temporalis muscles in retraction? | Suprahyoid muscles |
Which of the suprahyoid muscles does not directly influence the mandible? | Stylohyoid |
What needs to happen in order for the suprahyoids to depress the jaw? | The infrahyoids must stabilize the hyoid bone in a downward position. |
The vertical position of the hyoid bone is determined by what? | Contraction of the muscles attached to its superior and inferior borders. |
What structres do the infrahyoid muslces extend down to? | From the hyoid bone to the clavicle and sternum |
What are the three pairs of basic movements of the mandible? | elevation and depression/protrustion and retraction/right and left lateral shift |
What is the jaw held in position by? | A balance between the depressor and elevator muscles (except in occlusion) |
Name the two movements that require relaxation of the suprahyoids: | Elevation and protrusion |
Name the two movements that require contraction of the lateral pterygoid: | Depression and protrusion |
Name the two movements that require relaxation of the lateral pterygoid: | Retraction and elevation |
When the lateral pterygoids and suprahyoids contract to depress the mandible, there must be relaxation of which muscles? | Masseter, temporalis, and medial pterygoid |