10 Questions
What is the main function of the TMJ?
To facilitate jaw movement
What is the histological structure of the articular surface of the temporal bone?
Fibrous covering and compact bone
What is the function of the cartilaginous plate in the condylar head?
It acts as a growth center until the age of 20
How is the cancellous bone arranged in the condylar head?
In a radiating manner
What is the characteristic of the articular disc?
It is well vascularized and innervated at its periphery
What is the function of the retro-diskal pad?
To provide well-vascularized and innervated connection
What is the arrangement of collagen type I fibers in the central portion of the disc?
Tightly and organized
What is the role of the capsular ligament?
To allow smooth, synchronous motion of the condyle and disc
What divides the joint cavity into two compartments?
The articular disc
What type of cells are present in the synovial membrane?
Macrophage-like cells
Study Notes
TMJ (Temporomandibular Joint) Anatomy
- The TMJ is the joint between the temporal bone of the skull and the condyle of the mandible, responsible for jaw movement.
Articular Surfaces
- The temporal bone articulates from above, featuring: • Articular eminence and glenoid fossa • Fibrous covering with uneven thickness (thin at glenoid fossa, thick at eminence) • Bone structure consisting of thin layer of compact bone covering cancellous bone
- The condylar head articulates from below, featuring: • Fibrous covering ("Fibrocartilage") divided into two parts: • Fibrous layer (even thickness, composed of strong bundles of collagen type I fibers) • Cartilaginous plate (hyaline cartilage layer, acts as a growth center until age 20, with ossification taking place in the deep layer of the fibrocartilage) • Bone structure consisting of thin layer of compact bone covering cancellous bone, with cancellous bone trabeculae arranged in a radiating manner to provide maximum strength
Articular Disc
- The articular disc is an oval plate dividing the joint cavity into upper and lower compartments.
- Features of the disc: • Upper surface: concavo-convex • Lower surface: concave • Well vascularized and innervated at its periphery, but not in its central portion • Anteriorly inserted into the superior head of lateral pterygoid muscles • Posteriorly connected to the capsule by the retro-diskal pad (well vascularized and innervated) • Medial and lateral portions blend with the joint capsule and poles of the condyle, allowing the disc and condyle to move as a single unit
- Histological structure: • Collagen type I fibers arranged loosely and randomly, except in the central portion where they are arranged more tightly and organized • Few elastic fibers
Capsular Ligament
- Function: restricts movement of the disc away from the condyle, allowing smooth and synchronous motion of the condyle/disc.
- Composition: consists of an outer fibrous layer and an inner synovial layer (synovial membrane).
Joint Cavity
- Divided by the articular disc into upper and lower compartments.
- Lined by synovial membrane, which lines the entire capsule, except for the articular surfaces and disc (except its posterior region).
- Function of the synovial membrane: • Production of synovial fluid • Varying cell types (type A Macrophage like...)
This quiz covers the structure and function of the temporomandibular joint, including articular surfaces, temporal bone, and mandible.
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