JOINTS ARTICULATIONS 9

Classification of Joints: Structurally; 1. Fibrous joints -lack a synovial cavity -held by fibrous connective tissue with lots of collagen 2. Cartilaginous joints -lack a synovial cavity -held by cartilage

3. Synovial joints -have a synovial cavity (space between articulating bones) -bones connected by dense irregular connective tissue –may have additional ligaments.

Functionally: 1. Synarthrosis -immovable joint 2. Amphiarthrosis -slightly movable joint 3. Diarthrosis -freely movable joints -all synovial joints

FIBROUS JOINTS -little or no movement Sutures – Synarthrosis Fibrous connective tissue and irregular interlocking edges – Synostosis –sutures present in childhood that are replaced by bone in the adult -left and right sides of frontal bone

Syndesmoses – Fibrous joint with greater distance than in sutures – CT arranged as a bundle or a sheath *Distal tibiofibular joint *amphiarthrosis

Gomphoses Cone shaped peg fits into a socket – Teeth – Synarthrosis

CARTILAGINOUS JOINTS: Synchondrosis – Connecting material is hyaline cartilage *Epiphyseal plate * 1 st rib and sternum -synarthrosis

Symphyses – Ends of articulating bones are covered with hyaline cartilage – Bones connected by broad, flat disc of fibrocartilage – All occur in midline of the body Pubic symphysis Amphiarthrosis

SYNOVIAL JOINTS: Structure of a synovial joint Articular capsule -surrounds the synovial joint -2 layers *outer fibrous capsule

And…. -attaches to periosteum of articulating bones -flexible -some fibers arranged in parallel bundles called ligaments -ligaments hold bones together in synovial joint

Fig. 9-1a, p. 261

*synovial membrane -inner layer -may have articular fat pads

- secreted by the synovial membrane -thin film on articular capsule surfaces -similar in consistency to uncooked egg white - * Synovial fluid

More…. -lubricates joint -nourishes and removes waste -some phagocytic cells -“warm-up” reduces viscosity of synovial fluid

Articular discs (menisci) -pads of fibrocartilage -lie between the articular surfaces of the bone and attached to the fibrous capsule -modify the shape of the synovial cavity -bones fit more tightly -stabilizes the joint

Fig. 9-1b, p. 261

Reflect!

Clinical Applications: Torn Cartilage -tearing of articular discs -must be removed or may cause arthritis -arthroscopic surgery

Sprain- -twisting and wrenching of a joint -stretches and tears ligaments -no dislocation of bones -local swelling from damaged blood vessels

Strain -less serious than a sprain -stretched or partially torn muscle RICE - rest/ice/compression/elevation

TYPES OF SYNOVIAL JOINTS: Planar Joints – Articulating surfaces flat or slightly curved – Intercarpal joints, intertarsal joints – Permit gliding movements

Hinge Joints Concave surface of one bone fits into concave surface of another bone Knee, elbow, ankle Open and closing movement

Pivot Joints Rounded or pointed surface of one bone articulates with a ring formed by another bone and partly by a ligament -Atlas rotates around axis -atlanto-axial joint -Radioulnar joint –palms turn anterior and posterior

Condyloid Joints Convex oval shaped projection of one bone fits into the oval shaped depression of another. -Wrist and metacarpophalangeal joints 2-5

Saddle Joints Articular surface of one bone is saddle-shaped Other bone fits into the saddle Carpometacarpal joint –trapezium and thumb metacarpal

Ball and Socket Joints Ball like surface of one bone Cuplike depression of another Shoulder and hip joints

BURSAE AND TENDON SHEATHS Bursae – Saclike structures – Reduce friction – Shoulder and knee joints – Not strictly part of synovial joints – CT lined by a synovial membrane – Filled with fluid similar to synovail fluid – Between skin and bone – Between tendons and bones, muscles and bones, ligaments and bones

Bursitis – inflammation of the bursae -caused by trauma or infection (syphilis, TB) -rheumatoid arthritis -exertion

Tendon sheaths – Reduce friction – Tube-like bursae that wrap around tendons – Areas of considerable friction – Occurs there tendons pass through synovial cavities – Wrist, ankle, biceps brachii at the shoulder

Reflect -can you explain it?

TYPES OF MOVEMENT Angular Movements –increase or decrease in angle of articulating bones – Flexion – Extension – Lateral flexion – Hyperextension

Fig. 9-3a, p. 265

More…… Abduction -Movement of a bone away from the midline Adduction -Movement of a bone toward the midline Circumduction -Movement of the distal end of a body part in a circle Rotation -A bone revolves around its own longitudinal axis

Fig. 9-3b, p. 265

Fig. 9-4, p. 266

Fig. 9-5, p. 267

All Clear?

Rheumatism and Arthritis -inflammation, pain and stiffness of the joints -rheumatoid arthritis = diffuse CT disease autoimmune disease attacks cartilage and joint linings usually occurs bilaterally inflammation of the synovial membrane if untreated the synovial membrane produces specialized granulation tissue called pannus

More about R. Arthritis pannus adheres to surface of the articular cartilage an may erode the cartilage completely granulation tissue causes distortion of the fingers which is characteristic cartilage may erode completely, then exposed ends of bones will be joined by fibrous cartilage which will ossify and fuse the joint. Strikes smaller joints first.

osteoarthritis = degenerative joint disease -results from aging and irritation of the joints. “Wear and tear arthritis” leading cause of disability in older adults appears in synovial joints of weight bearing joints. Knees, hips, back, and hands.

Clinical signs of arthritis Characterized by the deterioration of the articular cartilage and the formation of new bone in the subchondral areas and at the margins of the joint. Cartilage slowly degenerates New osseous tissue forms and makes bumps and spurs. Movement of the joint is restricted Strikes larger joints first.

Gouty arthritis involves metabolic and endocrine systems uric acid builds up in the blood (waste product from metabolism of nucleic acid) gout sufferers produce too much uric acid or cannot excrete it excess uric acid reacts with sodium to form sodium urate. Sodium urate accumulates in soft tissues such as kidneys, cartilage of the ears and joints. Crystals in the joints erode the cartilage causing inflammation, swelling, and pain. Crystals will eventually destroy the cartilage.

Gouty Arthritis