Quiz e Flashcards sobre Anatomia das Juntas

Study Notes

Anatomy of Joints

The human body is made up of over 200 bones, connected by a variety of joints that allow for movement and support. Joints can be classified by the type of tissue present or by the degree of movement permitted. In this article, we will explore the three main types of joints: fibrous joints, cartilaginous joints, and synovial joints.

Fibrous Joints

Fibrous joints are where the bones are bound by a tough, fibrous tissue. They are typically joints that require strength and stability over range of movement. Fibrous joints can be further sub-classified into sutures, gomphoses, and syndesmoses.

Sutures

Sutures are immovable joints found between the flat, plate-like bones of the skull. They are most important in birth, as they allow for the skull to deform and pass through the birth canal. There is limited movement until about 20 years of age, after which they become fixed and immobile.

Gomphoses

Gomphoses are also immovable joints. They are found where the teeth articulate with their sockets in the maxilla (upper teeth) or the mandible (lower teeth). The tooth is bound into its socket by the strong periodontal ligament.

Syndesmoses

Syndesmoses are slightly movable joints. They are comprised of bones held together by an interosseous membrane. The middle radioulnar joint and middle tibiofibular joint are examples of a syndesmosis joint.

Cartilaginous Joints

In a cartilaginous joint, the bones are united by fibrocartilage or hyaline cartilage. There are two main types: synchondroses and symphyses.

Synchondroses

In a synchondrosis, the bones are connected by hyaline cartilage. These joints are immovable (synarthrosis). An example of a synchondrosis is the joint between the diaphysis and epiphysis of a growing long bone.

Symphyses

Symphysial joints are where the bones are united by a layer of fibrocartilage. They are slightly movable (amphiarthrosis). Examples include the pubic symphysis and the joints between vertebral bodies.

Synovial Joints

A synovial joint is defined by the presence of a fluid-filled joint cavity contained within a capsule. They are freely movable (diarthrosis) and are the most common type of joint found in the body. Synovial joints can be sub-classified into several different types, depending on the shape of their articular surfaces and the movements permitted: hinge, saddle, plane, pivot, condyloid, and ball and socket.

Hinge Joint

A hinge joint is an articulation between the convex end of one bone and the concave end of another. It is uniaxial, meaning it only permits movement along one axis, usually flexion and extension (bending or straightening). Examples include the elbow, knee, ankle, and interphalangeal joints.

Saddle Joint

A saddle joint, or an ellipsoid joint, is an articulation between the shallow depression of one bone and the rounded structure of one or more other bones. It is biaxial, meaning it permits two axes of movement: flexion/extension and medial/lateral (abduction/adduction). Examples include the carpometacarpal joints.

Plane Joint

The articular surfaces in a plane joint are relatively flat, allowing the bones to glide over one another. Examples include the acromioclavicular joint and the subtalar joint.

Pivot Joint

A pivot joint allows for rotation only. It is formed by a central bony pivot, which is surrounded by a bony-ligamentous ring. Examples include the proximal and distal radioulnar joints and the atlantoaxial joint.

Condyloid Joint

A condyloid joint contains a convex surface which articulates with a concave elliptical cavity. They are also known as ellipsoid joints. Examples include the wrist joint, metacarpophalangeal joint, and metatarsophalangeal joint.

Ball and Socket Joint

In a ball and socket joint, the ball-shaped surface of one rounded bone fits into the cup-like depression of another bone. It permits free movement in numerous axes. Examples include the hip joint and shoulder joint.

In conclusion, the anatomy of joints is a complex and fascinating topic, with each type of joint serving a specific function in the body. Understanding the differences between fibrous, cartilaginous, and synovial joints is essential for appreciating the complexity of the musculoskeletal system and the role of joints in supporting and facilitating movement.

Description

Explore the three main types of joints in the human body: fibrous joints, cartilaginous joints, and synovial joints. Learn about their characteristics, types, and functions in supporting and facilitating movement.