Jointsaka: 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

1. Articular cartilage Hyaline Spongy cushions absorb

compression Protects ends of bones

from being crushed

2. 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

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

Some joints…

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

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

• When you are finished describe the following inflammatory disorders:

• Bursitis• Arthritis (Osteo, Rhumatoid and

Gouty)• Tendonitis

6 synovial joints

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

Types of JointsHinge- Rounded process fits into concave

surface. Uniaxial.

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. 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. You are not

responsible for this on a quiz or test.

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

Selected synovial joints

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 surfacesSeveral ligaments stabilize

1. Radiocarpal joint Between radius and

proximal carpals (scaphoid and lunate)

Condyloid joint Flexion extension

adduction, abduction, circumduction

2. 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

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 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.