ch 9 summary of classifications of joints DESCRIPTION DEGREE OF MOVEMENT

**Suture**

Articulating bones united by thin layer of dense irregular connective tissue, found between skull bones; with age, some sutures replaced by synostosis (separate cranial cavity bones fuse into single bone).Immovable and slightly movable.

**Syndesmosis**

Articulating bones united by a varying amount of dense irregular connective tissue, usually a ligament or membrane.Slightly movable

**Synchondrosis**

Connecting material: hyaline cartilage.Slightly movable to immovable.

**Symphysis**

Connecting material: broad, flat disc of fibrous cartilage.Slightly movable to immovable.

**Plane**

Articulated surfaces flat or slightly curved.Many are biaxial: back-and-forth and side-to-side movements. Some are triaxial: back-and-forth, side-to-side, rotation.

**Hinge**

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Convex surface fits into concave surface.Uniaxial: flexion–extension.

**Pivot**

Rounded or pointed surface fits into ring formed partly by bone and partly by ligament.Uniaxial: rotation.

**Ellipsoid**

Oval-shaped projection fits into oval-shaped depression.Biaxial: flexion–extension, abduction–adduction.

**Saddle**

Articular surface of one bone is saddle-shaped; articular surface of other bone “sits” in saddle.Biaxial: flexion–extension, abduction–adduction.

**Ball-and-socket**

Ball-like surface fits into cuplike depression.Triaxial: flexion–extension, abduction–adduction, rotation.