chapter 9 anatomy and physiology

Joint (articulation)

Point where two bones meet

Arthrology

Study of joint structure, function & dysfunction

Kinesiology

Study of musculoskeletal movement; a branch of biomechanics; includes physics of blood circulation, respiration & hearing

Joint classification by anatomy

• fibrous

• cartilaginous

• synovial

Joint classification by mobility

• synarthroses (immovable)

• amphiarthroses (slightly movable)

• diarthroses (most mobile)

Fibrous joint

Joint where adjacent bones bound by collagen fibers, which emerge from matrix of one bone, cross the space between them & penetrate the matrix of the other bone

Sutures

Closely bind bones of skull (only found here) to each other; immobile or slightly mobile

Serrate sutures

Join bones with serrated margins (dovetail wood joint) Example: Coronal, sagittal, lambdoid sutures

Lap (squamous) sutures

Join bones that have overlapping beveled edges. Example: Squamous suture encircling most of the temporal bone.

Plane (butt) sutures

Join bones that have straight, nonoverlapping edges. Example: Intermaxillary suture in the roof of the mouth.

Syndesmoses

Bind bones with relatively long collagen fibers; more mobility than sutures

Example of syndesmoses

Radius and ulna joined by interosseous membrane, allowing for pronation and supination of the forearm.

Gomphoses

Bind teeth to jaw.

Cartilaginous joint

Joint where adjacent bones bound by cartilage; include these 2 types, synchondroses and symphyses.

Synchondrosis

Bones bound by hyaline cartilage; immoveable or slightly movable

Example of synchondrosis

Joint between first rib and sternum (slightly movable); in child or adolescent, epiphysis and diaphysis joined by cartilaginous epiphyseal plate (immovable)

Symphyses

Bones joined by fibrocartilage; slightly movable

Example of symphyses

Pubic symphysis, where left and right pubic bones joined by cartilaginous interpubic disc.

Function of pubic symphysis

Allows the adjoining hip bones to move slightly during childbirth & facilitates passage of the infant's head.

Synovial joint

Bones held together by fibrous joint capsule with thin film of lubricating synovial fluid between the bones; ends of bones covered in articular cartilage.

Most common type of joint

Synovial joints.

Examples of synovial joints

Knee, elbow, knuckles.

Mobility class of most synovial joints

Freely mobile diarthroses; some are amphiarthroses.

Fibrous joints

Joints where bones are connected by fibrous tissue.

Cartilaginous joints

Joints connected by cartilage.

Synchondroses

Synarthroses; example is epiphyseal plates.

Joint (articular) cavity

Gap filled with viscous, slippery, lubricating synovial fluid.

Articular cartilage

Bone surfaces covered in hyaline cartilage

Articular capsule

Double layered joint capsule that encloses the joint cavity.

Synovial membrane

Inner layer of the articular capsule that secretes synovial fluid

Fibrous capsule

Outer layer of the articular capsule made of dense fibrous connective tissue.

Bursa

Fibrous sac external to joint cavity filled with synovial fluid

Bursitis

Inflammation of a bursa.

Tendon

Cord or sheet of fibrous connective tissue connecting muscle to bone

Ligament

Connects bone to bone, similar to a tendon

Tendon sheath

Elongated bursa wrapped around a tendon

Tendinitis

Inflamed tendon sheath

Multiaxial

Joint can move in any of the three planes of space (x, y, and z).

Biaxial

Joint can move in two planes

Monaxial

Joint moves in one plane

Ball-and-socket joints

Hemispherical head of one bone fits into cuplike socket of the other bone; multiaxial

Examples of Ball-and-socket joints

Shoulder and hip joints

Condylar (ellipsoid) joints

Oval convex surface of one bone fits into complementary depression on the other bone; biaxial

Examples of Condylar joints

Radiocarpal joint of wrist; metacarpophalangeal joints of knuckles

Saddle joints

Saddle-shaped surface, concave in one direction and convex in the other; biaxial (but greater mobility than other biaxial joints)

Examples of Saddle joints

Trapeziometacarpal joint at base of thumb; sternoclavicular joint

Plane (gliding) joints

Bone surfaces are relatively flat; usually biaxial.

Examples of Plane joints

Between carpal bones of wrist, tarsal bones of ankle, patella and femur.

Hinge joints

Convex surface of one bone fits into concave depression on other bone, like a door hinge; monoaxial

Examples of Hinge joints

Elbow (humeroulnar), knee (femur & condyles of femur & slightly concave condyles of tibial plateau), interphalangeal (finger and toe) joints

Pivot joints

One bone spins (pivots) on its longitudinal axis; monoaxial

Examples of Pivot joints

Radioulnar joint at elbow; atlantoaxial joint between vertebrae C1 and C2

Flexion

Movement decreases joint angle.

Extension

Movement increases joint angle

Abduction

Movement of body part in the frontal plane away from midline of the body

Adduction

Movement of body part in the frontal plane toward midline of the body

Elevation

Movement raises body part in frontal plane

Depression

Movement lowers body part in frontal plane

Protraction

Anterior movement of body part in transverse plane

Retraction

Posterior movement of body part in transverse plane

Circumduction

One end of appendage is stationary while other end makes a circular motion

Rotation

Bone spins on its longitudinal axis

Medial (internal) rotation

Bone spins toward midline of body

Lateral (external) rotation

Bone spins away from midline of body

Supination

Forearm movement where palm turns to face anteriorly or upward.

Pronation

Forearm movement where palm turns to face posteriorly or downward

Flexion of spine

Forward bending movement.

Extension of spine

Straightens trunk or neck.

Lateral flexion

Tilting head or trunk to right or left.

Lateral excursion

Side-to-side movement of mandible

Medial excursion

Side-to-side movement of mandible in the opposite direction

Radial flexion of hand

Hand tilts toward thumb

Ulnar flexion of hand

Hand tilts toward little finger.

Flexion of fingers

Bending of fingers.

Extension of fingers

Straightening of fingers

Abduction of fingers

Movement of fingers away from the midline.

Adduction of fingers

Movement of fingers toward the midline.

Radial abduction of thumb

Movement of thumb away from the hand

Palmar abduction of thumb

Movement of thumb away from the palm

Opposition of thumb

Movement of thumb to touch other fingers

Reposition of thumb

Movement of thumb back to its original position

Dorsiflexion

Movement of foot so toes are elevated

Planar flexion

Movement of foot so toes point downward

Inversion

Foot movement that moves soles medially

Eversion

Foot movement that moves soles laterally

Range of motion (ROM)

Number of degrees through which one bone can move relative to another at that joint

Temporomandibular joint (TMJ)

Articulation between condyle of mandible and mandibular fossa of temporal bone

Key features of TMJ

Combines elements of condylar, hinge, and plane joints; allows elevation, depression, side-to-side movements, protraction, and retraction.

Glenohumeral (humeroscapular) joint

Articulation between head of humerus and glenoid cavity of scapula

Glenoid labrum

Offers stability to the shoulder joint

Rotator cuff muscles

Four muscles that have tendons that fuse with the joint capsule of the shoulder

Bursae

Several associated with the shoulder joint

Elbow joint

two articulations called humeroulnar joint and humeroradial join enclosed in a single joint capsule

Olecranon bursa

Cushions movements of tendons over olecranon of ulna

Radial collateral ligament

Restricts side movements of the elbow joint

Ulnar collateral ligament

Restricts side movements of the elbow joint

Proximal radioulnar joint

Near the elbow but not part of the elbow hinge joint; the disclike head of the radius fits into the radial notch of the ulna

Annular ligament

Encircles the head of the radius and attaches at each end of the ulna

Coxal (hip) joint

Head of femur articulates with acetabulum of hip bone.

Acetabulum

Deep socket that provides stability to the hip joint.