ball-and-socket joint

Examples of ball-and-socket joint in the following topics:

• Functional Classification of Joints

  • Functional classification of joints is based on the type and degree of movement permitted.
  • This category includes fibrous joints such as suture joints (found in the cranium) and gomphosis joints (found between teeth and sockets of the maxilla and mandible).
  • Most joints in this category include cartilaginous joints such as those found between vertebrae and the pubic symphysis.
  • Multiaxial – Includes the ball and socket joints.
  • Image of a skeleton and skematics of the different classes of synovial joints.

• Types of Synovial Joints

  • Synovial joints include planar, hinge, pivot, condyloid, saddle, and ball-and-socket joints, which allow varying types of movement.
  • These joints can be described as planar, hinge, pivot, condyloid, saddle, or ball-and-socket joints .
  • Ball-and-socket joints possess a rounded, ball-like end of one bone fitting into a cup-like socket of another bone.
  • Examples of ball-and-socket joints are the shoulder and hip joints .
  • (f) The hip and shoulder joints are the only ball-and-socket joints of the body.

• Types of Synovial Joints

  • The types of the synovial joints are based on their shapes and can be classified as plane, hinge, pivot, condyloid, saddle, and ball-and-socket.
  • A ball-and-socket joint occurs where one bone ends in a spherical head and the other bone has a round socket.
  • This joint creates the ball-and-socket movement found in such places as the hip and shoulder (glenohumeral).
  • Wind up for the pitch (ball-and- socket joint), raise your knee (compound joint/modified hinge joint), and throw that ball.
  • Hip joint: the ball of the femur head fits in the socket of the acetabulum of the pelvis.

• Synovial Joint Movements

  • A synovial joint, also known as a diarthrosis, is the most common and most movable type of joint in the body of a mammal.
  • Structural and functional differences distinguish synovial joints from cartilaginous joints (synchondroses and symphyses) and fibrous joints (sutures, gomphoses, and syndesmoses).
  • The main structural differences between synovial and fibrous joints are the existence of capsules surrounding the articulating surfaces of a synovial joint and the presence of lubricating synovial fluid within those capsules (synovial cavities).
  • The six types of joints include:
  • Saddle joints - permit the same movement as condyloid joints and combine with them to form compound joints

• Muscles of the Shoulder

  • Muscles of the shoulder include those that attach to the bones of the shoulder to move and stabilize the joint.
  • The shoulder or glenohumeral joint is a ball and socket joint formed between the humerus and scapula.
  • Due to the shallowness of the socket and relatively loose connections, the shoulder joint allows for a wide range of motion; however, this wide range makes the joint unstable and thus more prone to dislocation and injury than other joints.
  • Two other joints make up the shoulder; the acromioclavicular joint of the clavicle and scapula, which allows the arm to be raised above the head, and the sternoclavicular joint of the clavicle and sternum, which plays an important role in facilitating movement of the upper arm and connecting it to the rest of the skeleton.
  • The rotator cuff is a group of four muscles that pull the ball of the humerus into the shallow socket of the scapula, adding required stability.

• Gomphoses

  • A gomphosis is a fibrous joint that binds the teeth to bony sockets in the bones of the maxilla mandible.
  • A gomphosis is a joint that anchors a tooth to its socket.
  • Gomphoses line the upper and lower jaw in each tooth socket and are also known as peg and socket joints.
  • The gomphosis is made up of fibrous tissue, a collection of tough ligaments that attach to the socket and base of the tooth.
  • Periodontal infection and inflammation can also damage the joint, causing pain and erosion in the soft tissue.

• Classification of Joints on the Basis of Structure and Function

  • The structural classification divides joints into fibrous, cartilaginous, and synovial joints depending on the material composing the joint and the presence or absence of a cavity in the joint.
  • Gomphoses occur between teeth and their sockets; the term refers to the way the tooth fits into the socket like a peg .
  • The tooth is connected to the socket by a connective tissue called the periodontal ligament.
  • There are two types of cartilaginous joints: synchondroses and symphyses.
  • Knees, elbows, and shoulders are examples of synovial joints.

• Structural Classification of Joints

  • The type and characteristics of a given joint determines its degree and type of movement.
  • Joints can be classified based on structure and function.
  • Gomphosis is a type of joint found at the articulation between teeth and the sockets of the maxilla or mandible (dental-alveolar joint).
  • The fibrous tissue that connects the tooth and socket is called the periodontal ligament.
  • The knees and elbows are examples of synovial joints.

• Rotator Cuff Injury and Dislocated and Separated Shoulder

  • The main functions of the cuff are to stabilize the glenohumeral joint and rotate the humerus outward.
  • The shoulder joint is the most frequently dislocated major joint of the body .
  • In a typical case of a dislocated shoulder, a strong force that pulls the shoulder outward (abduction) or extreme rotation of the joint pops the ball of the humerus out of the shoulder socket.
  • Problems seen with a dislocated shoulder are tearing of the ligaments or tendons reinforcing the joint capsule and, less commonly, nerve damage.
  • Doctors treat a dislocation by putting the head of the humerus back into the joint socket (glenoid fossa) of the scapula.

• Arthroplasty

  • Partial arthroplasty (replacing the hip socket and femur head and neck) may be done to relieve pain and improve mobility.
  • Arthroplasty (literally "surgical repair of joint") is an operative procedure of orthopedic surgery performed, in which the arthritic or dysfunctional joint surface is replaced with something better or by remodeling or realigning the joint by osteotomy or some other procedure .
  • Osteotomy to restore or modify joint congruity is also an arthroplasty.
  • For the last 45 years, the most successful and common form of arthroplasty has been the surgical replacement of degenerated joint surfaces with prostheses.
  • This would involve replacing both the acetabulum (hip socket) and the head and neck of the femur.