Chapter 2
Geriatrics: Section II - Skeletal System
| TIS | Chapter 2 | |
ARTICULATIONS
I. CLASSIFICATION OF JOINTS
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
II. FIBROUS JOINTS
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
III. CARTILAGINOUS JOINTS
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
IV. SYNOVIAL 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")
V. MOVEMENTS AT SYNOVIAL JOINTS
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
