Thoracic limb arthrology

When 2 or more bones are united by fibrous, elastic or cartilaginous tissue, or by a combination of these tissues

How are joints formed

Fibrous joint

Cartilaginous joint

Synovial joint

What are the 3 types of joints

-contains a considerable amount of intervening connective tissue

-limited degree of movement

Ex: sutures between bones of the skull

What is a fibrous joint

Fibrous joints

Joints with considerable connective tissue and limited movement

-joint formed by union of cartilage (hyaline, fibrocartilage)

Ex: temporary fetal joints of growing bones, symphasises of the jaw and pelvis. Between vertebrae

What are cartilaginous joints

Cartilaginous joints

Joints formed by union of cartilage

-joints of the extremities

-provide greatest degree of movement

-most clinical issues with dislocation

What is a synovial joint

Synovial joint

Joint of the extremities with greatest degree of movement

Joint cavity

Joint capsule

Synovial fluid

Articular cartilage

What are the components of a synovial joint

The space of the cavity filled with synovial fluid

What is the joint cavity

Outer fibrous layer (capsular ligament)

-white fibrous tissue with yellow elastic fibers

-thickenings of this layer where bones move the least= collateral ligaments

Inner synovial membrane

-vascular connective tissue responsible for synovial fluid production

What is the joint capsule

Created by the inner synovial membrane

Lubricates contact surfaces of synovial joints

What is synovial fluid

Typically hyaline cartilage

Covers articular surfaces of the bones

Thickest in joints that bear the most weight

What is articular cartilage

Shoulder joint

-ball and socket joint between the glenoid cavity and head of humerus

-capable of movement in any direction- chief movements are flexion and extension of shoulder

-luxation is rare- muscles stabilize the joint (supra/infraspinatus, subscapularis, coracobrachialis)

What is the glenohumeral joint

Thickenings of the outer fibrous layer of the joint capsule

Medial glenohumeral ligament

Lateral glenohumeral ligament

What are the glenohumeral ligaments

Elbow joint

-hinge synovial joint

-flexion and extension

Compound joint- 3 bones

-condyle of humerus

-head of radius

-trochlear notch of ulna

What is the cubital joint

Collateral ligaments- thickenings of outer fibrous layer of joint capsule. Arise from epicondyles of the humerus

-lateral (ulnar) collateral ligament

-medial (radial) collateral ligament

Interosseus ligament:

-collagenous tissue uniting the radius and ulna proximally

What are the ligaments of the elbow joint

The anconeal process of the ulna projects into the olecranon fossa of the humerus

Why is elbow luxation uncommon in dogs