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Lecture Notes: Unit II: Principles of Support and Movement
Chapter Nine – Joints
I. Introduction
A. A joint (articulation or arthrosis) is a point of contact between two or more bones, between cartilage and
bones, or between teeth and bones
B. Arthrology is the scientific study of joints
C. Kinesiology is the study of the motion of the human body
II. Joint Classification
A. Functional Classification
1. Synarthrosis--immovable joint
2. Amphiarthrosis--slightly movable joint
3. Diarthrosis--freely movable joint
B. Structural Classification
1. Fibrous joints
a. General characteristics.
(1) Lack a synovial cavity
(2) Articulating bones held together by fibrous connective tissue
(3) Little or no movement
b. Types of fibrous joints
(1) Sutures--thin layer of dense fibrous connective tissue that unites skull bones
(a) Synostoses: suture joints that have ossified (ie: metopic suture between R + L halves of frontal bone)
(b) Sutures (ie: coronal, sagittal, lambdoidal, squamosal, etc.) and synostoses are functionally
classified as synarthroses
(c) Fontanels: aka “soft-spots” are fibrous connective tissue filled spaces between neurocranial
bones which will eventually be replaced by intramembranous ossification. Know: anterior
(largest, 18-24 mo); posterior (2 mo), anterolateral (3 mo); posterolateral (12 mo).
(2) Syndesmoses
(a) Greater distance between articulating bones
(b) Greater amount of fibrous material present .
(c) Functionally, syndesmoses are classified as amphiarthroses
(d) Example: distal tibiofibular joint
(3) Gomphoses
(a) Cone-shaped pegs fit into sockets
(b) Teeth in the alveoli of the alveolar ridges of the maxillae and mandible
(c) Gomphoses are functionally classified as a synarthroses
2. Cartilaginous joints
a. General characteristics
(1) Lack a synovial joint
(2) Little or no movement
(3) Tightly connected to either fibrocartilage or hyaline cartilage
b. Types of cartilaginous joints
(1) Synchondroses
(a) Hyaline cartilage is the connecting material
(b) Examples: epiphyseal plate; joint between the sternal manubrium and first rib
( c) Functionally, synchondroses are synarthroses
(2) Symphyses
(a) End of bone is covered with hyaline cartilage
(b) Connected by a broad, flat disc of fibrocartilage
( c) Examples: pubic symphysis, manubrium with body of sternum, intervertebral joints
(d) Functionally, symphyses are amphiarthroses
3. Synovial joints
a. General characteristics
(1) Presence of a synovial joint cavity between the articulating bones
(2) Functionally, synovial joints are freely movable aka: diarthroses
b. Synovial Joint structure
(1) Articular cartilage covers the articulating surfaces of bones
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(2) Articular capsule surrounds the synovial joint
(a) Fibrous capsule
1. Outer layer
2. Dense irregular connective tissue
3. Ligaments are fibrous capsule bundles which run parallel and reinforce the joint
(b) Synovial membrane
1. Areolar connective tissue with elastic fibers (NO epithelial tissue present)
2. Articular fat pads are accumulations of adipose tissue at synovial joints
3. Synovial fluid: viscous, clear /pale yellow fluid which lubricates the joint and supplies nutrients
(3) Articular discs
(a) Modify the shape of the joint surfaces of the articulating bones
(b) Maintain the stability of the joint
(c) Direct flow of synovial.fluid to areas of greatest friction
c. Types of Synovial joints
(1) Planar joints
(a) Premit mainly side-to-side and back-and-forth gliding movements
(b) Nonaxial
(c) Intercarpal, intertarsal, sternoclavicular, acromioclavicular, sternocostal, vertebrocostal
(2) Hinge joints
(a) Convex surface of one bone fitting into a concave surface of another bone
(b) Elbow, knee, ankle, interphalangeal
(3) Pivot joint
(a) Round or pointed surface of one bone fits into a ring formed by another bone and ligament
(b) Rotational movement
( c) Monaxial
(d) Atlas rotating around the axis
(4) Ellipsoidal joint
(a) Oval-shaped condyle of one bone fits into an elliptical cavity of another bone
(b) Flexion-extension, abduction-adduction, circumduction
(c) Joint between the carpals and the radius
(5) Saddle joint
(a) One bone whose articular surface is saddle-shaped; and another whose articular surface is
shaped like a rider sitting in the saddle
(b) Flexion-extension, abduction-adduction, circumduction
(6) Ball-and-socket joints
(a) Ball-shaped surace of one bone fits into the cuplike depression of another
(b) Flexion-extension, abduction-addduction, rotation, circumduction
(c) Shoulder joint and hip joint
d. Bursae
(l) Synovial-fluid filled saclike structures that cushion the movement of one body part over another
(2) Bursitis is inflammation of bursae, caused by trauma, infection, or by rheumatoid arthritis
e. Tendon sheaths--tubelike bursae that wrap around tendons where there is considerable friction
f. Types of synovial joint movement
(1) Gliding
(a) Relatively flat boney surfaces move back and forth and from side to side with respect to
each other
(b) Gliding movements occur at plantar joints
(2) Angular movements (increase or decrease in the angle between articulating bones)
(a) Flexion--decrease in the angle between articulating bones
(b) Extension--increase in the angle between articulating bones
(c) Lateral flexion--movement of the trunk sideways to the right or left at the waist
(d) Hyperextension--continuation of extension beyond the anatomical position
(e) Abduction—movement of a body part away from the midline of the body
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(f) Adduction--movement of a body part toward the midline of the body
(g) Circumduction
1. Movement of the distal end of a part of the body as if to draw a circle .
2. Occurs as a result of a continuous sequence of flexion, abduction, extension
and adduction. (Note: there exists NO separate axis or plane of movement.)
(3) Rotation
(a) Bone revolves around its own longitudinal axis
(b) Medial rotation--anterior surface of the bone is turned toward midline
(c) Lateral rotation--anterior surface of the bone is turned away from midline
(4) Special movements
(a) Elevation--upward movement of a body part
(b) Depression--downward movement of a body part
(c) Protraction--movement of a body part anteriorly in the transverse plane
(d) Retraction--movement of the protracted part back to the anatomical position
(e) Inversion--movement of the soles medially at the intertarsal joints so they face toward each other
(f) Eversion--movement of the soles laterally at the intertarsal joints so they face away from each other
(g) Dorsiflexion--bending of the foot at the ankle in the direction of the superior surface
(h) Plantar flexion - bending of the foot at the ankle joint in the direction of plantar surface
(i) Supination--movement of the forearm at the proximal and distal radioulnar joints in
which the palm is turned anteriorly or superiorly
(j) Pronation--movement of the forearm at the proximal and distal radioulnar joints in
which the distal end of the radius crosses over the distal end of the ulna
and the palm is turned posteriorly or inferiorly.
(k) Opposition—movement of the thumb at the carpometacarpal joint in which the thumb
moves across the palm to touch the tips of the fingers on the same hand