9.6 Types of synovial joints

Condyloid joint example:

Examples of condyloid joints are the radiocarpal (wrist) and metacarpophalangeal joints (between the metacarpals and proximal phalanges) of the second through fifth digits

Saddle joints example:

An example of a saddle joint is the carpometacarpal joint between the trapezium of the carpus and metacarpal of the thumb.

ball‐and‐socket joint example

Examples of ball‐and‐socket joints are the shoulder and hip joints. At the shoulder joint, the head of the humerus fits into the glenoid cavity of the scapula. At the hip joint, the head of the femur fits into the acetabulum of the hip (coxal) bone.

Hinge joint example:

Examples of hinge joints are the knee (actually a modified hinge joint, which will be described later; see Exhibit 9.E), elbow, ankle, and interphalangeal joints (between the phalanges of the fingers and toes).

Pivot joint examples:

Examples of pivot joints are the atlanto‐axial joints, in which the atlas rotates around the axis and permits the head to turn from side to side as when you shake your head "no" (see Figure 9.8a), and the radioulnar joints that enable the palms to turn anteriorly and posteriorly as the head of the radius pivots around its long axis in the radial notch of the ulna

Hinge joint

In a hinge joint, or ginglymus joint (JIN‐gli‐mus), the convex surface of one bone fits into the concave surface of another bone (Figure 9.10b). As the name implies, hinge joints produce an angular, opening‐and‐closing motion like that of a hinged door. Hinge joints are uniaxial (monaxial) because they typically allow motion around a single axis. Hinge joints permit only flexion and extension

Plane joints examples:

Some examples of plane joints are the intercarpal joints (between carpal bones at the wrist), intertarsal joints (between tarsal bones at the ankle), sternoclavicular joints (between the manubrium of the sternum and the clavicle), acromioclavicular joints (between the acromion of the scapula and the clavicle), sternocostal joints (between the sternum and ends of the costal cartilages at the tips of the second through seventh pairs of ribs), and vertebrocostal joints (between the heads and tubercles of ribs and bodies and transverse processes of thoracic vertebrae).

Plane joints

The articulating surfaces of bones in a plane joint (PLĀN), also called a planar joint (PLĀ‐nar), are flat or slightly curved (Figure 9.10a). Plane joints primarily permit back‐and‐forth and side‐to‐side movements between the flat surfaces of bones, but they may also rotate against one another. Many plane joints are biaxial, meaning that they permit movement in two axes. An axis is a straight line around which a bone rotates (revolves) or slides. If plane joints rotate in addition to sliding, then they are triaxial (multiaxial), permitting movement in three axes

Condyloid joints

or ellipsoidal joint, the convex oval‐shaped projection of one bone fits into the oval‐shaped depression of another bone (Figure 9.10d). A condyloid joint is biaxial because the movement it permits is around two axes (flexion‐extension and abduction-adduction), plus limited circumduction (remember that circumduction is not an isolated movement).

Saddle joints

or sellar joint (SEL‐ar) the articular surface of one bone is saddle‐shaped, and the articular surface of the other bone fits into the "saddle" as a sitting rider would sit (Figure 9.10e). The movements at a saddle joint are the same as those at a condyloid joint: biaxial (flexion-extension and abduction-adduction) plus limited circumduction

ball‐and‐socket joint

or spheroid joint (SFĒ‐royd) consists of the ball‐like surface of one bone fitting into a cuplike depression of another bone (Figure 9.10f). Such joints are triaxial (multiaxial), permitting movements around three axes (flexion-extension, abduction-adduction, and rotation)

Pivot joints

or trochoid joint (TRŌ‐koyd), the rounded or pointed surface of one bone articulates with a ring formed partly by another bone and partly by a ligament (Figure 9.10c). A pivot joint is uniaxial because it allows rotation only around its own longitudinal axi

Synovial joints are divided into six categories based on type of movement:

plane, hinge, pivot, condyloid, saddle, and ball‐and‐socket.