Mandibular Movements Part 1
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Questions and Answers

What type of joint is the temporomandibular joint (TMJ)?

  • Fibrous joint
  • Synovial joint (correct)
  • Hinge joint
  • Cartilaginous joint

What is the main function of the fibrous articular disk in the TMJ?

  • To absorb shock
  • To divide the joint into two compartments (correct)
  • To reduce friction between bones
  • To enhance the strength of ligaments

Which of the following muscles is primarily responsible for the elevation of the mandible?

  • Mylohyoid
  • Digastrics
  • Lateral pterygoid
  • Masseter (correct)

The TMJ allows what type of rotational movement to take place in the lower compartment?

<p>Hinging (B)</p> Signup and view all the answers

What type of connective tissue covers the articular surfaces of the TMJ?

<p>Dense fibrous connective tissue (B)</p> Signup and view all the answers

Which muscle is NOT involved in the voluntary control of mandibular movements?

<p>Sternocleidomastoid (C)</p> Signup and view all the answers

What is the correct term for the gliding (translational) movements of the mandible that occur in the upper compartment of the TMJ?

<p>Sliding movement (C)</p> Signup and view all the answers

Which muscle primarily helps in the positioning and guiding of the mandible?

<p>Lateral pterygoid (C)</p> Signup and view all the answers

What anatomical structure separates the two compartments of the TMJ?

<p>Fibrous articular disk (A)</p> Signup and view all the answers

Which function does NOT belong to the superficial portion of the masseter muscle?

<p>Retrusion (B)</p> Signup and view all the answers

What is the significance of interarch and intraarch relationships of the teeth?

<p>They influence the health and function of the masticatory system. (B)</p> Signup and view all the answers

What characterizes centric relation?

<p>The condyles are in the most unstrained position. (B)</p> Signup and view all the answers

Which of the following describes the types of movement involved in centric relation?

<p>Rotation and translation. (C)</p> Signup and view all the answers

In what position does a hinge axis movement begin?

<p>Centric relation. (D)</p> Signup and view all the answers

What aspect is independent during complete static intercuspation?

<p>Condylar position. (A)</p> Signup and view all the answers

What may or may not coincide with maximum intercuspation?

<p>Centric relation. (D)</p> Signup and view all the answers

What does the direction of motion refer to in the context of dental movement?

<p>The path taken by the jaw during movement. (A)</p> Signup and view all the answers

What is an important characteristic of the maximum condylar position?

<p>It indicates an unstrained state of the condyles. (C)</p> Signup and view all the answers

Which of the following best illustrates the clinical significance of dental movement?

<p>It helps in diagnosing dental diseases. (C)</p> Signup and view all the answers

What is the role of the glenoid fossa related to dental movement?

<p>It accommodates the condyles during specific jaw positions. (D)</p> Signup and view all the answers

What is the primary function of the muscle that originates from the temporal fossa?

<p>Elevation and retrusion (A)</p> Signup and view all the answers

What is the insertion point of the muscle that elevates and protrudes the mandible?

<p>Medial surface of angle of mandible (A)</p> Signup and view all the answers

During bilateral contraction of the lateral pterygoid muscle, what movement occurs?

<p>Protrusion of the mandible (C)</p> Signup and view all the answers

Which ligament functions primarily to limit and restrict mandibular movements?

<p>Collagenous connective tissue ligaments (B)</p> Signup and view all the answers

What role do the suprahyoid and infrahyoid muscles play during the contraction of the digastric muscle?

<p>They fix the hyoid bone (D)</p> Signup and view all the answers

What type of movement characterizes the centric relation of the mandible?

<p>Combination of rotation and translation (D)</p> Signup and view all the answers

What muscle action is primarily associated with the lateral pterygoid muscle during unilateral contraction?

<p>Lateral movement to the opposite side (C)</p> Signup and view all the answers

Which origin point corresponds to the muscle responsible for keeping the articular disk properly aligned?

<p>Infratemporal surface of greater wing of sphenoid (B)</p> Signup and view all the answers

The digastric muscle primarily functions to do what to the mandible when contracted?

<p>Depress the mandible (A)</p> Signup and view all the answers

Which of the following statements about ligaments is true?

<p>They limit and restrict border movements (C)</p> Signup and view all the answers

Flashcards

Centric Relation

The position where the condyles of the mandible are in their most retruded, unstrained position within the glenoid fossa. It's the starting point for all mandibular movements.

Rotation and Translation

Types of motion that occur during jaw movements. Rotation involves pivoting around a fixed axis, while translation refers to a sliding movement.

Planes of Motion

The direction in which the jaw moves. This can be described in planes, such as sagittal, horizontal, and vertical.

Degree of Movement

The amount of movement of the jaw.

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Interarch Relationship

The relationship between the upper and lower teeth when the jaw is in centric relation.

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Intraarch Relationship

The relationship between the teeth within the same arch (upper or lower).

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Clinical Significance of Movement

How the movement of the jaw affects the health and function of the chewing system.

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Maximum Intercuspation

The complete intercuspation of opposing teeth when the mandible is in centric relation. It may or may not coincide with maximum intercuspation.

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Temporomandibular Joint (TMJ)

The joint between the temporal bone (cranium) and the mandible, enabling complex jaw movements.

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Dense Fibrous Connective Tissue in TMJ

Fibrous connective tissue covering the articular surfaces of the TMJ, instead of hyaline cartilage found in most other synovial joints.

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Fibrous Articular Disc in TMJ

A fibrous disc within the TMJ, attached to muscles, dividing the joint into upper and lower compartments, allowing for wide range of jaw movements.

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Superior Joint Cavity of TMJ

The upper compartment of the TMJ, involved in gliding (translational) movements of the jaw.

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Inferior Joint Cavity of TMJ

The lower compartment of the TMJ, responsible for hinging (rotational) movements of the jaw.

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Rotational Movement of TMJ

The movement of the jaw around a fixed point, like opening and closing the mouth.

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Translational Movement of TMJ

The movement of the jaw along a surface, like moving the jaw forward or backward.

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Muscles of Mastication

Muscles that control the movement of the mandible, working under voluntary control.

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Elevator Muscles

Muscles that elevate the mandible, including the masseter, temporalis, and medial pterygoid.

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Depressor Muscles

Muscles that depress the mandible, including the digastric, mylohyoid, stylohyoid, and geniohyoid.

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Temporalis Muscle

The temporalis muscle is a fan-shaped muscle located on the side of the head. It originates from the temporal fossa and inserts on the coronoid process and anterior border of the ramus of the mandible.

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Medial Pterygoid Muscle

The medial pterygoid muscle is a thick, quadrilateral muscle located deep within the face. It originates from the medial surface of the lateral pterygoid plate, palatine bone, and maxillary tuberosity. It inserts on the medial surface of the angle of the mandible and the inferior surface of the ramus.

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Lateral Pterygoid Muscle

The lateral pterygoid muscle is a small, triangular muscle located at the back of the jaw. It originates from the infratemporal surface of the greater wing of the sphenoid and inserts on the neck of the condyle and articular disc of the temporomandibular joint.

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Digastric Muscle

The digastric muscle is a two-bellied muscle that helps to depress the mandible. It originates from the mastoid notch (medial to the mastoid process) and inserts on the intermediate tendon attached to the hyoid bone.

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Mylohyoid Muscle

The mylohyoid muscle is a thin sheet-like muscle that helps to elevate the hyoid bone and depress the mandible. It originates from the lingual surface of the mandible, just above the lower border, and inserts on the intermediate tendon attached to the hyoid bone.

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TMJ Ligaments

The TMJ ligaments are composed of collagenous connective tissues that restrict mandibular movements. They do not actively participate in joint function, but instead serve as passive restraining devices.

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TMJ Movements

The temporomandibular joint allows for several types of movements, including:

  • Opening and closing the mouth: Depression and elevation of the mandible.

  • Side-to-side movements: Lateral excursion of the mandible.

  • Protrusive movements: Protrusion of the mandible forward.

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Study Notes

Mandibular Movements Part 1

  • The temporomandibular joint (TMJ) is the articulation between the temporal bone and the mandible.
  • It is one of the most complex joints in the body.
  • The TMJ is a hinge and gliding joint, and it is the most frequently used joint in the body.
  • The TMJ contains a fibrous articular disc.
  • The disc divides the joint into upper and lower compartments, enabling a wider range of mandibular movement.
  • The disc allows for both rotational and translational movements.
  • Rotational movements occur in the lower compartment.
  • Translational (gliding) movements take place in the upper compartment.

Factors Regulating Mandibular Movements

  • Temporomandibular Joint: The articulation between the temporal bone and mandible.
  • Muscles: Active muscles control voluntary mandibular movement.
  • Ligaments: Passive structures that limit and restrict mandibular movement.
  • Dentition and supportive structures: Exact interarch and intraarch relationships of the teeth directly affect the health and function of the masticatory system.

Muscles

  • Masseter: Originates from the zygomatic arch and inserts on the lateral aspect of the lower border of the ramus.
  • Function: elevation and protrusion (superficial); elevation (deep portion).
  • Temporalis: Originates from the temporal fossa, inserting at the coronoid process and anterior border of the ramus; function: elevation and retrusion.
  • Medial pterygoid (internal pterygoid): Originates from the medial surface of the lateral pterygoid plate, palatine bone, and maxillary tuberosity. Inserts on the medial surface of the angle of the mandible and inferior surface of the ramus; function: elevation, protrusion.
  • Lateral pterygoid (superior head): Originates from the infratemporal surface of the greater wing of sphenoid, inserts at the neck of condyle and articular disc; function: keeps the disc aligned with the condyle during function.
  • Lateral pterygoid (inferior head): Originates from the lateral surface of the lateral pterygoid plate, inserts at the neck of the condyle; function: protrusion, lateral movement.
  • Depressor Muscles: Digastric, geniohyoid, mylohyoid, stylohyoid, geniohyoid, and other suprahyoid and infrahyoid muscles depress the mandible.

Ligaments

  • Ligaments consist of collagenous connective tissues with specific lengths.
  • They do not stretch.
  • They are passive restraining devices that limit and restrict mandibular movements.
  • Important ligaments of the TMJ include the joint capsule, temporomandibular ligament, sphenomandibular ligament, and stylomandibular ligament.

Dentition and Supportive Structures

  • Each tooth is specifically shaped for its function.
  • The precise interarch and intraarch relationships of the teeth significantly impact the health and function of the masticatory system.

Centric Relation

  • Maxillomandibular relationship with the condyles in the furthest back (retruded), relaxed position within the glenoid fossa. This is the starting position for hinge movements.
  • It's the most superior condylar position from which a hinge-axis movement can happen.
  • Maximum Intercuspation: the complete static contact of opposing teeth, independent of the condylar position.
  • Centric Occlusion: the occlusion (contact) of opposing teeth when the mandible is in centric relation. It may not be the same as maximum intercuspation (when teeth mesh together most fully).

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Mandibular Movements PDF

Description

This quiz examines the anatomy and function of the temporomandibular joint (TMJ), which facilitates complex mandibular movements. It covers the structure of the joint, the role of muscles and ligaments in movement, and the importance of dental relationships. Test your knowledge and understanding of these crucial components in oral physiology.

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