Anatomy of Temporalis Muscle
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Anatomy of Temporalis Muscle

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Questions and Answers

What is the type of joint that the TMJ is classified as?

  • Mono-axial hinge joint
  • Bi-axial condylar synovial joint (correct)
  • Uni-axial pivot joint
  • Tri-axial ball-and-socket joint

    • What is the function of the medial pterygoid muscle when both muscles act together?

  • Protrude and deviate the mandible to the same side
  • Elevate and retract the mandible
  • Elevate and protrude the mandible (correct)
  • Depress and protrude the mandible

    • Where does the medial pterygoid muscle insert into?

  • Articular tubercle of temporal bone
  • Medial surface of lateral pterygoid plate
  • Medial surface of angle and ramus of mandible, below the mandibular foramen (correct)
  • Lateral surface of mandibular fossa

    • What is the function of the lateral pterygoid muscle when one muscle acts alone?

    <p>Protrude and deviate the mandible to the opposite side</p> Signup and view all the answers

    What is the characteristic of the articular surfaces of the TMJ?

    <p>Covered by white fibrocartilage</p> Signup and view all the answers

    What is the articular surface of the TMJ below?

    <p>Head (condylar process) of mandible</p> Signup and view all the answers

    Which nerve supplies the masseter muscle?

    <p>Masseteric nerve</p> Signup and view all the answers

    What is the origin of the temporalis muscle?

    <p>Inferior temporal line</p> Signup and view all the answers

    What is the function of the posterior fibers of the temporalis muscle?

    <p>Retraction of the mandible</p> Signup and view all the answers

    Where does the lateral pterygoid muscle insert?

    <p>Front of the neck of mandible</p> Signup and view all the answers

    What happens when both lateral pterygoid muscles act together?

    <p>Protrusion and depression of the mandible</p> Signup and view all the answers

    What is the function of the deep vertical fibers of the masseter muscle?

    <p>Elevation of the mandible</p> Signup and view all the answers

    What is the origin of the lower head of the lateral pterygoid muscle?

    <p>Lateral surface of the lateral pterygoid plate</p> Signup and view all the answers

    What happens when one lateral pterygoid muscle acts alone?

    <p>Protrusion of the mandible to the opposite side</p> Signup and view all the answers

    What is the shape of the articular disc's upper surface?

    <p>Concavo-convex</p> Signup and view all the answers

    Where is the temporomandibular ligament attached above?

    <p>Root of zygomatic arch</p> Signup and view all the answers

    What is the function of the temporomandibular ligament?

    <p>Supports the joint</p> Signup and view all the answers

    What type of tissue is the articular disc composed of?

    <p>Dense avascular fibrocartilage</p> Signup and view all the answers

    What is the shape of the temporomandibular ligament?

    <p>Triangular</p> Signup and view all the answers

    Where is the fibrous capsule attached below?

    <p>Neck of mandible</p> Signup and view all the answers

    Which ligament is attached to the spine of sphenoid bone?

    <p>Spheno-mandibular ligament</p> Signup and view all the answers

    What is the primary action of the lateral pterygoid muscle in the TMJ?

    <p>Depression of the mandible</p> Signup and view all the answers

    Which nerve is responsible for the nerve supply of the TMJ?

    <p>Auriculotemporal nerve and Mandibular nerve</p> Signup and view all the answers

    What is the direction of mandible dislocation?

    <p>Only forwards</p> Signup and view all the answers

    Which movement of the TMJ is done by the medial and lateral pterygoids of both sides acting alternately?

    <p>Side-to-side movement</p> Signup and view all the answers

    Which artery supplies blood to the TMJ?

    <p>Maxillary artery and superficial temporal artery</p> Signup and view all the answers

    Which ligament is attached to the angle and posterior border of ramus of mandible?

    <p>Stylo-mandibular ligament</p> Signup and view all the answers

    Which movement of the TMJ is done by the posterior horizontal fibers of temporalis?

    <p>Retraction</p> Signup and view all the answers

    Study Notes

    Temporalis Muscle

    • Origin: inferior temporal line, floor of temporal fossa, and temporal fascia
    • Insertion: tip and medial surface of coronoid process of mandible, and anterior border of ramus of mandible
    • Nerve supply: 2 deep temporal nerves, from anterior division of mandibular nerve
    • Action: elevation of mandible to close the mouth (antigravity) by anterior (vertical) fibers, and retraction of mandible by posterior (horizontal) fibers

    Masseter Muscle

    • Origin: superficial oblique fibers from lower border of zygomatic arch, deep vertical fibers from inner surface of zygomatic arch
    • Insertion: lateral surface of ramus of mandible
    • Nerve supply: masseteric nerve, from anterior division of mandibular nerve
    • Action: elevation of mandible to close the mouth (antigravity) by deep vertical fibers, and protrusion of mandible by superficial oblique fibers

    Lateral Pterygoid Muscle

    • Origin: upper head from infratemporal surface and crest of the greater wing of sphenoid, lower head from lateral surface of the lateral pterygoid plate
    • Insertion: into the front of neck of mandible (pterygoid fovea), as well as the capsule and articular disc of the temporomandibular joint
    • Nerve supply: branch from the anterior division of mandibular nerve
    • Action: protrusion and depression of the mandible to open the mouth, deviation of mandible to opposite side when one muscle acts alone, and side-to-side movement when both muscles act alternately

    Medial Pterygoid Muscle

    • Origin: superficial head from maxillary tuberosity, deep head from medial surface of lateral pterygoid plate
    • Insertion: into medial surface of angle and ramus of mandible, below the mandibular foramen
    • Nerve supply: branch from the main trunk of the mandibular nerve
    • Action: elevation and protrusion of the mandible when both muscles act together, deviation of mandible to opposite side when one muscle acts alone, and side-to-side movement when both muscles act alternately

    Temporomandibular Joint (TMJ)

    • Type: bi-axial condylar synovial joint
    • Articular surfaces: head (condylar process) of mandible below, and mandibular fossa and articular tubercle of temporal bone above
    • Articular surfaces are covered by white fibrocartilage with collagen fibers predominating and few cartilage cells
    • Capsule: attached above to margins of mandibular fossa and articular eminence, and below to neck of mandible, with lateral thickening forming temporomandibular ligament
    • Articular disc: oval plate of dense avascular fibrocartilage dividing joint cavity into upper and lower compartments, with upper surface concavo-convex and lower surface concave, and periphery attached to fibrous capsule all-around

    Ligaments of TMJ

    • Temporomandibular ligament: triangular ligament on lateral aspect of the joint, attached above to root of zygomatic arch and below to lateral aspect of neck of mandible, supporting the joint
    • Stylo-mandibular ligament: cord-like ligament on posterior aspect of the joint, attached above to anterior aspect of styloid process near its tip and below to angle and posterior border of ramus of mandible
    • Spheno-mandibular ligament: cord-like ligament on medial aspect of the joint, attached above to spine of sphenoid bone and below to lingula of mandible

    Movements of TMJ

    • Depression (opening of mouth): combined movements of hinging and gliding, done by lateral pterygoid muscle assisted by gravity and other muscles
    • Elevation (closure of mouth, occlusal position): done by medial pterygoid, temporalis, and masseter of both sides
    • Protrusion (forward movement): done by medial and lateral pterygoids of both sides, with little effect by superficial fibers of masseter
    • Retraction (backward movement): done by the posterior horizontal fibers of temporalis
    • Side-to-side (grinding or chewing movement): done by medial and lateral pterygoids of both sides acting alternately

    Nerve Supply and Blood Supply of TMJ

    • Nerve supply: auriculotemporal nerve and masseteric nerve (from mandibular nerve)
    • Blood supply: maxillary artery and superficial temporal artery (from external carotid artery)

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    Description

    Learn about the origin, insertion, nerve supply, and action of the Temporalis Muscle, a crucial facial muscle involved in mandible movement.

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