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Chapter 8 - A&P - Joints

Functions of Joints

hold bones to one another; in some cases, permit the human skeleton to be flexible (movement)

ARTICULATIONS

contact points between bones or cartilage and bones; closer fit at contact point stronger joint.

Explain how joints are classified structurally and functionally.

Structurally focuses on the material binding the bones together; Functional is based on the amount of movement allowed to the joint):

Functional joints

Classified by how much movement is allowed
1) Synoarthrosis (immovable)
2) amphiarthrosis (slightly movable)
3) diarthrosis (freely movable)

Structural Joints

focuses on the material binding the bones together
1) Fibrous
2) Cartilagenous
3) Synovial

Fibrous Joints

no joint cavity; joined together by dense fibrous connective; tissuea joint where the material between bones consists of fibrous connective tissue that allows very little or no movement between them.

Types of Fibrous Joints

1. Sutures (skull)
2. Syndemoses (tibiofibular fiber)
3. Gomphoses (teeth)

Fibrous Joints: Sutures

Fibrous joint; occur between bones of skull and use very short dense connective tissue fibers to hold the bones together

Fibrous Joints: Syndemoses

Fibrous joint connected by a ligament or membrane that allows some movement (radius and ulna or tibia and fibula)

Fibrous Joints: Gomphoses

Fibrous joint in which a cone-shaped peg fits into a socket (i.e. union of tooth root in bony socket)

Cartilaginous Joints

Have no joint cavity; allow only slight movement, bones held together by cartilage.

1. Sychondroses
2. Symphyses

Cartilaginous Joints: Sychondroses

Cartilaginous Joint; involve a bar or plate of hyaline cartilage uniting the bones, such as the epiphyseal plate (between 1st rib and sternum)

Cartilaginous Joints: Symphyses

Cartilaginous Joint; bones are joined by fibrocartilage such as the pubic symphysis; the articular surfaces are covered with articular cartilage that is then fused to an intervening pad or plate of fibrocartilage

Synovial Joints

joints in which the articulating bones are separated by a fluid-containing joint cavity; all are freely movable diarthroses; Examples - all limb joints, and most joints of the body

Synovial Cavity

space between articulating bones within joint

Synovial Joints - 6 distinguish features

1. Joint (Synovial Cavity)
2. Articular Cartilage
3. Articular Capsule
4. Accessory Ligaments
5. Articular Disc (MENISCI)
6. Bursae

Synovial Joints - distinguish features:
1. Joint (Synovial Cavity)

potential space between bones that contains a small amount of synovial fluid

Synovial Joints - distinguish features:
2. Articular Cartilage

hyaline cartilage that covers ends of bones in synovial joints

Synovial Joints - distinguish features:
3. Articular Capsule

A. Fibrous capsule- the outer layer of the articular capsule; dense irregular connective tissue that is continuous with the periosteum layer of the joining bones; some fibers arranged in parallel bundles =LIGAMENTS
B. Synovial Membrane- inner; loose connective tissue with elastic fibers & adipose tissue; secretes SYNOVIAL FLUID which lubricates the joints and nourishes the cartilage; has phagocytic cells, has hyaluronic acid + intestinal fluid made from blood plasma, greater movement the less viscous, up to .1oz

Synovial Joints - distinguish features:
4. ACCESSORY LIGAMENTS

a) EXTRACAPSULAR - outside art. capsule (eg. fibular collateral ligament of knee)

b) INTRACAPSULAR - within art. capsule but excluded from synovial cavity by reflections of synovial membrane (eg. cruciate ligament of knee)

Synovial Joints - distinguish features:
5. ARTICULAR DISC (MENISCI)

cushion of dense, specialized connective tissue that divides the articular space into upper and lower compartments, also known as meniscus; maintains stability

Synovial Joints - distinguish features:
6. BURSAE

tiny sacs of fluid that are located near joints and help reduce friction ; found where excessive rubbing (skin over bone, tendons and bone, muscles and bone)

SYNOVIAL JOINT TYPES

1. GLIDING (ARTHRODIA)
2. HINGE (GINGLYMUS)
3. PIVOT (TROCHOID)
4. ELLIPSOIDAL (CONDYLOID)
5. SADDLE (SELLARIS)
6. BALL & SOCKET (SPHEROID

SYNOVIAL JOINT TYPES:
1. GLIDING (ARTHRODIA)

anterior surface; small, flat, concave; non-axial movement. example is between carplas and tarsals
- a joint that allows one bone to slide over the othe

SYNOVIAL JOINT TYPES:
2. HINGE (GINGLYMUS)

spool like surface fits into concave surface; mono axial (flex/extend); a joint which allows movement in one plane, can flex or extend in that plane, (eg. elbow/ankle, interphalangeal)

SYNOVIAL JOINT TYPES:
3. PIVOT (TROCHOID)

rounded, pointed or concave surface fits into ring formed by part bone/ligament; mono axial (rotational movement around a single axis) (eg.atlantoaxial joint)

SYNOVIAL JOINT TYPES:
4. ELLIPSOIDAL (CONDYLOID)

Oval part of one bone fits into an elliptical cavity of another bone.; biaxial (flex/extend, adduct/abduct) (eg. radiocarpal joint)

SYNOVIAL JOINT TYPES:
5. SADDLE (SELLARIS)

articular surface concave in 1 direction, convex in other; biaxial(flex/extend, adduct/abduct) (eg. carpometacarpal joint of thumb)

SYNOVIAL JOINT TYPES:
6. BALL & SOCKET (SPHEROID

ball into cup like depression; tri axial (flex/extend, adduct/abduct/rotational) (eg.shoulders/hips)

JOINT MOVEMENT

A. GLIDING
B. ANGULAR
C. FLEXION
D. EXTENSION
E. ABDUCTION
F. ADDUCTION
G. ROTATION
H. CIRCUMDUCTION
I.. SPECIAL

JOINT MOVEMENT:
A. GLIDING

back and forth/side to side; no angular or rotary motion (eg. between tarsals and carpals); One flat bone surface glides or slips over another similar surface

JOINT MOVEMENT:
B. ANGULAR

changes angles between bones

JOINT MOVEMENT:
C. FLEXION

decrease angle between anterior surface of art. bones (except for toe & knee) (eg. bend head forward)

JOINT MOVEMENT:
D. EXTENSION

increase angle between anterior surface of art. bones (eg. resumes anatomical position)

JOINT MOVEMENT:
E. ABDUCTION

away from body midline (eg. raise arm/leg to the side)

JOINT MOVEMENT:
F. ADDUCTION

movement towards body midline (eg. resume anatomical position)

JOINT MOVEMENT:
G. ROTATION

around it's own axis
MEDIAL ant. surface of bone or extremity towards midline (eg. rotate palm inward)
LATERAL ant. surface of bone or extremity away from
midline (eg. rotate palm outward)

JOINT MOVEMENT:
H. CIRCUMDUCTION

distal end of bone moves in circle while proximal end is stable (eg. rotate outstretched arm)

JOINT MOVEMENT:
I.. SPECIAL

• INVERSION movement of foot/sole medially at ankle joint

• EVERSION movement of foot/sole laterally at ankle joint

• DORSIFLEXION flex foot at ankle joint

• PLANTAR FLEXION extend foot at ankle joint

• PROTRACTION move mandible/clavicle forward parallel to ground

• RETRACTION move mandible/clavicle backward parallel to ground

• SUPINATION forearm movement where in palm is turned ant. or sup. with flexed arm

• PRONATION forearm movement where in palm is turned post. or inf. with flexed arm

• ELEVATION upward body movement (eg. close mouth)

• DEPRESSION downward body movement (eg. open mouth)

Chapter 8 - A&P - Joints

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