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Questions and Answers
Where does the lateral pterygoid muscle insert?
Where does the lateral pterygoid muscle insert?
Which muscle is responsible for the retraction of the mandible?
Which muscle is responsible for the retraction of the mandible?
Which nerve supplies the muscles of mastication?
Which nerve supplies the muscles of mastication?
What ligament attaches to the ramus of the mandible?
What ligament attaches to the ramus of the mandible?
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Which muscle has fibers that are fan-shaped with three sets?
Which muscle has fibers that are fan-shaped with three sets?
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The lateral pterygoid muscle is involved in which action?
The lateral pterygoid muscle is involved in which action?
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Which nerve is related to both the otic ganglion and chorda tympani?
Which nerve is related to both the otic ganglion and chorda tympani?
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Where is the lateral pterygoid muscle located?
Where is the lateral pterygoid muscle located?
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Which blood vessels are found in the infratemporal fossa?
Which blood vessels are found in the infratemporal fossa?
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Study Notes
Temporomandibular Joint (TMJ)
- Type: Biaxial condylar synovial joint
- Located between the head of the mandible and the mandibular fossa and articular tubercle
Articular Surfaces
- Fibrous capsule attached to:
- Above: Margins of the mandibular fossa and articular tubercle
- Below: Neck of the mandible
- Thickened laterally to form the temporomandibular ligament
Ligaments
- Temporomandibular ligament:
- Triangular, thickened band of the lateral part of the capsule
- Attached above to the articular tubercle and below to the lateral and posterior surfaces of the neck of the mandible
- Stylo-mandibular ligament:
- From the anterior border of the styloid process to the angle and posterior border of the mandible
- Separates the parotid from the submandibular gland
- Spheno-mandibular ligament:
- From the spine of the sphenoid to the lingula of the mandible
- Pterygo-mandibular ligament:
- From the pterygoid hamulus to the posterior end of the mylohyoid line of the mandible
Articular Disc
- Oval plate of dense fibrous tissue separating the joint cavity into upper and lower compartments
- Upper surface: Concavo-convex
- Lower surface: Concave
- Attached to the fibrous capsule all around and receives the insertion of the lateral pterygoid muscle
Nerve Supply and Blood Supply
- Nerve supply: Fine branches from the auriculo-temporal nerve and nerve to masseter
- Blood supply:
- Maxillary artery
- Superficial temporal artery
Movements of the Mandible (TMJ)
- Depression (opening the mouth):
- Combined movement of simple hinge movement and gliding movement of the head
- Mainly produced by lateral pterygoid muscles assisted by gravity
- Elevation (closing the mouth, occlusal position):
- Reversed movements to depression
- Produced by medial pterygoid, temporalis, and masseter muscles
- Protraction (forward movement):
- Produced by lateral and medial pterygoids and superficial fibers of the masseter muscle
- Retraction (backward movement):
- Produced by posterior fibers of the temporalis muscle
- Side to side movement (for grinding and chewing):
- Produced by medial and lateral pterygoid muscles acting alternately
Temporal and Infratemporal Fossae
- Temporal Fossa:
- Region on the side of the head below the temporal lines and above the zygomatic arch
- Contents: Temporalis muscle, deep temporal vessels, and nerves
- Infratemporal Fossa:
- Region below and medial to the zygomatic arch, behind the maxilla, and deep to the ramus of the mandible
- Contents:
- Muscles of mastication: Temporalis, medial and lateral pterygoid muscles
- Blood vessels: Maxillary artery and its branches, pterygoid venous plexus
- Nerves: Mandibular nerve, otic ganglion, and chorda tympani
- Ligaments: Sphenomandibular ligament
Muscles of Mastication
- Temporalis:
- Fan-shaped muscle with three sets of fibers (anterior, middle, and posterior)
- Origin: Temporal fossa, temporal fascia, and inferior temporal line
- Insertion: Tip and medial surface of the coronoid process and anterior border of the ramus of the mandible
- Masseter:
- Origin: Temporal fossa, temporal fascia, and inferior temporal line
- Insertion: Tip and medial surface of the coronoid process and anterior border of the ramus of the mandible
- Actions: Elevation of the mandible by anterior fibers and retraction by posterior fibers
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Description
Test your knowledge on the anatomy of the Temporomandibular Joint (TMJ), including its type, articular surfaces, fibrous capsule, and ligaments.
