Joints aka: articulations

Classification of Joints Functional classification (arthr = joints) (Focuses on amount of movement) Synarthroses (immovable joints) – most common in the axial skeleton Amphiarthroses (slightly movable joints) – most common in the axial skeleton Diarthroses (freely movable joints) – most common in the appendicular skeleton

Classification of Joints Structural classification (Based on the material binding them and presence or absence of a joint cavity) Fibrous Cartilagenous Synovial

Fibrous joints Bones connected by fibrous tissue: dense regular connective tissue No joint cavity Slightly movable or immovable Types Sutures Syndesmoses

Sutures Only between bones of skull Fibrous tissue continuous with periosteum Ossify and fuse in middle age:

Syndesmoses In Greek: “ligament” Bones connected by ligaments only Amount of movement depends on length of the fibers: longer than in sutures

Cartilagenous joints Articulating bones united by cartilage Lack a joint cavity Not highly movable Two types Synchondroses (singular: synchondrosis) Sympheses (singular: symphesis)

Synchondroses Literally: “junction of cartilage” Hyaline cartilage unites the bones Immovable (synarthroses) Examples: Epiphyseal plates Joint between rib’s and the costal cartilage and of the sternum

Sympheses Literally “growing together” Fibrocartilage unites the bones Slightly movable (amphiarthroses) Resilient shock absorber Provide strength and flexibility Hyaline cartilage on articular surfaces of bones to reduce friction Examples Intervertebral discs Pubic symphysis of the pelvis

Synchondroses and sympheses Also pubic symphsis

Synovial joints Include most of the body’s joints All are diarthroses (freely movable) All contain fluid-filled joint cavity

General Structure of Synovial Joints Articular cartilage Hyaline Spongy cushions absorb compression Protects ends of bones from being crushed Joint (synovial) cavity Potential space Small amount of synovial fluid

General structure of synovial joints (cont.) 3. Articular (or joint) capsule Two layered Outer*: fibrous capsule of dense irregular connective tissue continuous with periosteum Inner*: synovial membrane of loose connective tissue (makes synovial fluid) Lines all internal joint surfaces not covered by cartilage* * * *

General structure of synovial joints (cont.) 4. Synovial fluid Filtrate of blood Contains special glycoproteins Nourishes cartilage and functions as slippery lubricant “Weeping” lubriication 5. Reinforcing ligaments (some joints) Capsular (most) – thickened parts of capsule Extracapsular Intracapsular

General structure of synovial joints (cont.) 6. Nerves Detect pain Monitor stretch (one of the ways of sensing posture and body movements) 7. Blood vessels Rich blood supply Extensive capillary beds in synovial membrane (produce the blood filtrate)

General structure of synovial joints

Some joints… Articular disc or meniscus (literally “crescent”) Only some joints Those with bone ends of different shapes or fitting poorly Some to allow two kinds of movement (e.g. jaw) Made of fibrocartilage Examples: knee TMJ (temporomandibular joint) sternoclavicular joint

Bursae and tendon sheaths Contain synovial fluid Not joints but often associated with them Act like ball bearings Bursa means “purse” in Latin Flattened sac lined by synovial membrane Where ligaments, muscles, tendons, or bones overlie each other and rub together Tendon sheath Only on tendons subjected to friction

Bursae and tendon sheaths

When you are finished describe the following inflammatory disorders: Bursitis Arthritis (Osteo, Rhumatoid and Gouty) Tendonitis Synovial joints classified by shape (of their articular surfaces) Working with a book and a partner or alone create a chart that Names, describes and provides examples of the following synovial joints Plane Hinge Pivot Condyloid Saddle Ball-and-socket

6 synovial joints Classified by the shape of their articular surface Plane Hinge Pivot Condyloid Saddle Ball-and-socket

Types of Joints Hinge- 
Rounded process fits into concave surface. Uniaxial.

Ball and Socket- Spherical head fits into deep concave surface Ball and Socket- 
Spherical head fits into deep concave surface. Multiaxial. They are found in the hips and shoulders. (Hip, Shoulder)

Gliding- In a gliding or plane joint flat bones slide past each other Gliding- 
In a gliding or plane joint flat bones slide past each other. Mid-carpal and mid-tarsal joints are gliding joints. Non-axial. (Hands (intercarpal), Feet (intertarsal))

Saddle- Both surfaces of the bones have both concave and convex regions with the shapes of the two bones complementing one other and allowing a wide range of movement. (carpals and metacarpal of the Thumb)

Pivot Joint: Round end of bone fits into a sleeve or ring of bones concave. Uniaxial. Condyloid Joint: oval or egg shaped end fits into a concave shape. Reduced ball and socket joint. Biaxial.

The following slides show specific joints The following slides show specific joints. You are not responsible for this on a quiz or test.

Shoulder (glenohumeral) joint Selected synovial joints Shoulder (glenohumeral) joint Stability sacrificed for mobility Ball and socket: head of humerus with glenoid cavity of scapula Glenoid labrum: rim of fibrocartilage Thin, loose capsule Strongest ligament: coracohumeral Muscle tendons help stability Rotator cuff muscles add to stability Biceps tendon is intra-articular

Elbow joint Hinge: allows only flexion and extension Annular ligament of radius attaches to capsule Capsule thickens into: Radial collateral ligament Ulnar collateral ligament Muscles cross joint

Wrist joint Two major joint surfaces Several ligaments stabilize Radiocarpal joint Between radius and proximal carpals (scaphoid and lunate) Condyloid joint Flexion extension adduction, abduction, circumduction Intercarpal or midcarpal joint Between the proximal and distal rows of carpals

Hip (coxal) joint Ball and socket Moves in all axes but limited by ligaments and deep socket Three ext. ligaments “screw in” head of femur when standing Iliofemoral Pubofemoral Ischiofemoral

Acetabular labrum diameter smaller than head of femur Dislocations rare Ligament of head of femur supplies artery Muscle tendons cross joint Hip fractures common in elderly because of osteoporosis

Knee joint Largest and most complex joint Primarily a hinge Compound and bicondyloid: femur and tibia both have 2 condyles Femoropatellar joint shares joint cavity At least a dozen bursae Prepatellar Suprapatellar

Lateral and medial menisci “torn cartilage” Capsule absent anteriorly Capsular and extracapsular ligaments Taut when knee extended to prevent hyperextension

Fibular and tibial collateral ligaments Patellar ligament Continuation of quad tendon Medial and lateral retinacula Fibular and tibial collateral ligaments Called medial and lateral Extracapsular

Cruciate ligaments Cross each other (cruciate means cross) Anterior cruciate (ACL) Anterior intercondylar area of tibia to medial side of lateral condyl of femur Posterior cruciate Posterior intercondylar area of tibia to lateral side of medial condoyle

Cruciate ligaments

Knee injuries Flat tibial surface predisposes to horizontal injuries Lateral blow: multiple tears ACL injuries Stop and twist Commoner in women athletes Heal poorly Require surgery

Ankle joint Hinge joint Distal tibia and fibula to talus Dorsiflexion and plantar flexion only Medial deltoid ligament Lateral ligaments: 3 bands Anterior talofibular Posterior talofibular Calcaneofibular Anterior and posterior tibiofibular (syndesmoses)

Right ankle, lateral view

Temporomandibular joint (TMJ) Head of mandible articulates with temporal bone Disc protects thin mandibular fossa of temporal bone

Sternoclavicular joint Saddle joint Only other example is trapezium and metacarpal 1 (thumb), allowing opposion Sternum and 1st costal (rib) cartilage articulate with clavicle Very stable: clavicle usually breaks before dislocation of joint Only bony attachment of axial skeleton to pectoral girdle

Disorders of joints Injuries Inflammatory and degenerative conditions Sprains Dislocations Torn cartilage Inflammatory and degenerative conditions Bursitis Tendonitis Arthritis Osteoarthritis (“DJD” – degenerative joint disease) Rheumatoid arthritis (one of many “autoimmune” joint disorders) Gout (crystal arthropathy)

Arthritis

Bursitis Inflammation of the Bursa (fluid filled sac surrounding the joint). A bursa can become inflamed from injury, infection (rare in the shoulder), or due to an underlying rheumatic condition. Bursitis is typically identified by localized pain or swelling, tenderness, and pain with motion of the tissues in the affected area.

Tendonitis Sometimes the tendons become inflamed for a variety of reasons, and the action of pulling the muscle becomes irritating. If the normal smooth gliding motion of your tendon is impaired, the tendon will become inflamed and movement will become painful. This is called tendonitis, and literally means inflammation of the tendon. The most common cause of tendonitis is overuse.