Chapter 2
Geriatrics: Section II - Skeletal System



articulations = joints

* def: a place of union between two or more bones

-- Two ways to classify joints:

1) structure

2) movement

A. Structure

1) Fibrous Joints:

* dense regular CT (fibrous CT) connects bones
* no joint cavity

2) Cartilaginous Joints:

* cartilage binds the bone
* no joint cavity

3) Synovial Joints:

* ligaments support articulating bones
* contains a joint cavity

B. Movement

1) Synarthroses: immovable joints

2) Amphiarthroses: slightly moveable

3) Diarthroses: freely moveable


A. Suture: dense regular CT binds bones

* immovable joint

B. Syndesmosis: bones held together by interosseous ligaments

* slight movement

C. Gomphosis: tooth root attached to jaw by fibers - immovable joint


A. Symphysis: bones separated by pad of fibrocartilage

* limited movement
* exs: symphysis pubis, intervertebral discs

B. Synchondrosis: bone segments separated by hyaline cartilage

* no movement
* ex: epiphyseal plate
* ex: costochondral joints


A. Structure

-- bones bound by ligaments
-- fibroelastic joint capsule
-- lining capsule is a synovial membrane
-- bones lined with articular cartilage
-- bursas

B. Kinds of Synovial Joints

1) Hinge:

* permits bending in one plane
* surface of one bone is concave, and the other is convex
* most common kind of synovial joint

2) Pivot:

* rotation about a central axis
* one bone is conical-shaped, fits in depression of another bone

3) Gliding:

* side-to-side movements
* articulating surfaces are flat

4) Condyloid:

* biaxial movements
* one bone surface is oval and convex, the other bone surface is concave

5) Saddle:

* wide range of movement
* each bone has a concave surface in one direction, and a convex surface in another

6) Ball and Socket:

* greatest range of movement
* one bone has rounded, convex surface
("ball"), the other a cuplike cavity ("socket")


A. Flexion: decreases joint angle in the A-P plane

* special kinds of flexion at ankle joint:

1) dorsiflexion: dorsum of foot is elevated
2) plantar flexion: bringing foot and toes closer to back of leg

B. Extension: increases joint angle in A-P plane

C. Abduction: body part moved away from the midline of the body, in a lateral direction

D. Adduction: body part moved toward the midline of the body, in a medial direction

E. Rotation: movement of a body part around its own axis

* special kinds of rotation of forearm:

1) supination: palm of hand facing anteriorly
2) pronation: palm of hand facing posteriorly

F. Circumduction: circular, conelike movement of a body segment

G. Inversion: movement of sole of foot inward or medially

H. Eversion: movement of sole of foot outward or laterally

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