articulations bio 238 copyright 2010, john wiley & sons, inc

Articulations

BIO 238

Copyright 2010, John Wiley & Sons, Inc.

Joint Classification

A joint is where two bones meet* Joints may be classified by structure or by

function

The structural classification of joints: Fibrous joints (bones held together by dense

collagen fibers) Cartilaginous joints (bones held together by

cartilage) Synovial joints (bones held together by ligaments)


Joint Classification

The functional classification of joints:

Synarthrosis (an immovable joint) Amphiarthrosis (a slightly movable joint) Diarthrosis (a freely movable joint)


Joints (Fibrous Joints) Lack a synovial cavity The articulating bones are held very closely together by dense

irregular connective tissue Fibrous joints permit little or no movement

3 types of fibrous joints: Sutures Syndesmoses Gomphoses

Joints (Fibrous Joints) Sutures

Immovable joint Occur only between the skull bones

Syndesmoses Permits slight movement Interosseous membrane Between the tibia and fibula in the leg

Gomphoses Immovable joint Joint in which a cone-shaped peg fits

into a cup shaped socket Articulations of the teeth with the

sockets of the maxillae and mandible

Syndesmoses


Joints (Cartilaginous Joints) Lack a synovial cavity Allow little or no movement The joint is tightly connected by cartilage

2 types of cartilaginous joints:

Synchondroses Symphyses

Cartilaginous Joints Synchondroses

The Connecting tissue is hyaline cartilage Found in Epiphyseal (growth) plate in bones

Symphyses Slightly movable joint Ends of the articulating bones are covered with hyaline cartilage,

but a disc of fibrocartilage connects the bones Pubic Symphysis is between the anterior surfaces of the hip

bones Also found in the intervertebral joints between the vertebrae

Synchondrosis


Symphysis


Synovial Joints

Components of a synovial joint: Ligaments hold bones together for extra

support Synovial cavity a space allowing a joint to be

freely movable Articular Capsule

A sleeve-like capsule enclosing the synovial cavity The articular capsule is composed of 2 layers:

an outer fibrous capsule an inner synovial membrane

Synovial FluidSecreted by the synovial membrane lining the capsule

Functions to reduce friction by:lubricating the joint

absorbing shock

supplying oxygen and nutrients to the cartilage

removing carbon dioxide and metabolic wastes from the cartilage


Synovial Joints

Accessory Ligaments and Articular Discs May be present in some joints for example the knee

joint

Collateral ligaments of the knee joint (Medial and Lateral)

Cruciate ligaments of the knee joint (Anterior and Posterior)

Menisci ( C shaped and O shaped) Pads of cartilage lie between the articular surfaces of the bones Allows bones of different shapes to fit together more tightly

Nerve and Blood Supply Nerve and Blood Supply

Nerve endings convey information about pain from the joint to the spinal cord and brain

Nerve endings respond to the degree of movement and stretch at a joint

Arterial branches from several different arteries merge around a joint before penetrating the articular capsule


Synovial Joints Bursae and Tendon Sheaths

Bursae Sac-like structures containing fluid similar to

synovial fluid Located between tendons, ligaments and bones Cushion the movement of these body parts

Tendon sheaths Wrap around tendons Reduce friction at joints


Specific terminology is used to designate the movements that occur at joints

Movements are grouped into four main categories: 1) Gliding 2) Angular movements 3) Rotation 4) Special movements

Types of Movements at Synovial Joints


Gliding Simple movement back-and-forth and from side-to-side There is no significant alteration of the angle between the bones Limited in range Intercarpal joints

Angular Movements Increase or a decrease the angle between articulating bones Angular movements include:

Flexion Extension Lateral flexion (side bending) Hyperextension Abduction Adduction Circumduction



Flexion Decreases the angle between articulating bones Bending the trunk forward

Extension Increases the angle between articulating bones Flexion and extension are opposite movements

Lateral flexion Movement of the trunk sideways to the right or left at the waist

Hyperextension Continuation of extension beyond the normal extension Bending the trunk backward

Abduction Movement of a bone away from the midline Moving the humerus laterally at the shoulder joint

Adduction Movement of a bone toward the midline Movement that returns body parts to normal position from abduction



Circumduction Movement of a body part in a circle Moving the humerus in a circle at the shoulder joint

Rotation A bone revolves around its own longitudinal axis Turning the head from side to side as when you shake your head “no”



Special Movements Elevation Depression Protraction Retraction Inversion Eversion Dorsiflexion Plantar flexion Supination Pronation Opposition



Types of Synovial Joints Synovial joints are classified based on type of

movement

Planar (Plane Joints) Hinge Pivot Condyloid Saddle Ball-and-socket


Types of Synovial Joints Planar Joints

Primarily permit back-and-forth and side-to-side movements Intercarpal joints

Pivot Joints Allow for rotation Found in the radioulnar and alanto-axial joints

Hinge Joints Produce an opening and closing motion like that of a hinged door Permit only flexion and extension Knee and elbow

Condyloid Oval-shaped condyle fits into an ellipsoidal socket Joint between carpals and wrist

Types of Synovial Joints

Saddle Two saddle shaped bones fitting together Found in joint between thumb metacarpal and wrist carpal.

Ball and socket Provides the greatest ROM Found in the hip and shoulder joints



Temporomandibular Joint


Ball-and-socket joint formed by the head of the humerus and the scapula

More freedom of movement than any other joint of the body

Shoulder Joint


Hinge joint formed by the humerus, the ulna, and the radius

Elbow Joint


Hip Joint Ball-and-socket joint formed by the femur and the hip

bone


Knee Joint

Largest and most complex joint of the body

Modified hinge joint


Range of Motion (ROM)

Refers to the range, measured in degrees of a circle, through which the bones of a joint can be moved

Measured in a scale up to 360 degrees Measured using a goniometer Range of motion allows us to measure a persons

movements and compare them to an average person’s range to determine if they have an injury or impairment


Factors that contribute to keeping the articular surfaces in contact and affect range of motion

Structure or shape of the articulating bones

Strength and tension of the joint ligaments

Arrangement and tension of the muscles

Contact of soft parts

Hormones

Disuse


Aging and Joints May result in decreased production of synovial fluid The articular cartilage becomes thinner Discs and muscle may have decrease in water content Ligaments shorten and lose some of their flexibility Osteoarthritis increases with age Stretching, aerobic exercises and strength training has shown

to be helpful in minimizing the effects of aging Exercise helps to maintain the effective functioning of

ligaments, tendons, muscles, synovial fluid, and articular cartilage by increasing nutrition to the joint

Furthermore weight bearing stimulates the joint to produce more bone which prevents osteoarthritis

Joint Diseases

Osteoarthritis The most common type of arthritis A degenerative disease that results from aging

and wear. The articular cartilages gradually disintegrate,

which causes pain and restricts movement.


Joint Diseases

Rheumatoid Arthritis A chronic autoimmune condition Often the most painful and crippling type of

arthritis The synovial membrane thickens, synovial fluid

accumulates causing swelling, and articular cartilages are destroyed.

The joint is invaded by fibrous connective tissue that ultimately ossifies, making the joint immovable.


Joint Diseases

Dislocation- the displacement of bones forming a joint.

Subluxation- a slight dislocation Sprains result from tearing or excessive

stretching of the ligaments and tendons at a joint without a dislocation.

Bursitis- the inflammation of a bursa. It may be caused by excessive use or injury


Joint Diseases

Herniated disc is a condition in which the nucleus pulposis of an intervertebral disc protrudes beyond the edge of a vertebra. The protruding disk may place pressure on a spinal nerve and cause considerable pain.


Arthrocentesis


Treatment for Damaged Joints Arthroplasty

Joints may be replaced surgically with artificial joints Most commonly replaced are the hips, knees, and shoulders

Hip Replacements Partial hip replacements involve only the femur Total hip replacements involve both the acetabulum and head of

the femur Knee Replacements

Actually a resurfacing of cartilage and may be partial or total Potential complications of arthroplasty include infection, blood

clots, loosening or dislocation of the replacement components, and nerve injury


Hip Joint Replacement

Healthcare Applications: For therapists range of motion (ROM) will be

an important tool to determine a clients limitations and a motivating factor for improvement in musculoskeletal injuries.

During the acute stages of many of these conditions, massage is contraindicated. However it can be used in later stages to ease muscle tension, reduce pain, and maintain flexibility.

articulations bio 238 copyright 2010, john wiley & sons, inc

Documents

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