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Chapter 9 Articulations (Joints) 9 Articulations.

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1 Chapter 9 Articulations (Joints) 9 Articulations

2 An Introduction to Articulations
Arthrology – science of joint structure, function, and dysfunction Kinesiology – the study of musculoskeletal movement Articulations/joints Body movement occurs at joints (articulations) where two bones connect A joint cannot be both mobile and strong. The greater the mobility, the weaker the joint. Joint strength decreases as mobility increases Mobile joints are supported by muscles and ligaments, not bone-to-bone connections Joint name – typically derived from the names of the bones involved atlanto-occipital joint, glenohumeral joint, radioulnar joint Joint Structure - Determines direction and distance of movement (range of motion or ROM). Two Methods of Classification Range of motion of the joint = Functional classification Anatomical structure of the joint = Structural (what it is made of) classification

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5 Articulations Classifications
Range of Motion Anatomical Structure Joints are classified according to the manner in which the adjacent bones are bound to each other, determines how freely the bones can move Bony Fibrous Cartilaginous Synovial capsule Synarthrosis: little to no movement Synostosis- Suture - bony Gomphosis - fibrous Synchondrosis- cartilage Amphiarthrosis: slightly moveable Syndesmosis - fibrous Symphyses - cartilage Diarthrosis: freely moveable Synovial joints -

6 Range of Motion: SYNARTHROSES
SYNARTHROSES (“syn”-together; “arthro”-joint) Little to no movement Very strong Edges of bones may touch or interlock; no joint cavity Four (4) types of synarthrotic joints FIBROUS Structure Suture – fibrous to bony Synostosis - bony- occurs when fibrous material is replaced by bone in an adult it becomes Gomphosis - fibrousy Fibrous joints contain a thin layer of dense fibrous connective tissue uniting bones of the skullin anadult- CARTILAGE Structure Synchondrosis –cartilaginous

7 Synarthroses- FIBROUS
SYNOSTOSIS / SUTURE –fused fibers/cartilage to bone Bones interlocked; adds strength of decreases incidence of fracture Are bound by dense fibrous connective tissue Immovable Metopic suture of skull Epiphyseal LINES of long bones- cartilage to bony suture Fusion of 1st rib and sternum GOMPHOSIS (“gomph=nail; osis=bolt”) Fibrous connection (periodontal ligament) Binds teeth to socket collagen fibers attach tooth to jawbone allows the tooth to move some under the stress of chewing

8 SYNCHONDROSIS - Cartilage
“Syn” - junction bound by “Chondro” – cartilage “Osis”- process, condition Rigid hyaline cartilage bridge - sternum / ribs Epiphyseal plate of hyaline cartilage in growing long bones, temporary Epiphyseal line - permanent

9 Range of Motion: AMPHIARTHROSES
More movable than synarthrosis Stronger than freely movable joint SYNDESMOSIS (syn-with; desmos- band) Fibrous interosseous membrane or ligament Longer collagenous fibers Less movable: distal tibia/fibular More movable radius/ulna- allows for supination/pronation SYMPHYSES Bones separated by fibrocartilage; compressible and resilient -acts as shock absorber and permits limited movement; Designed for strength and flexibility Intervertebral disc Symphyses pubis

10 Range of Motion: SYNOVIAL JOINTS
DIARTHROSIS (“dia”- through, apart) = very moveable At ends of long bones Complex; Most familiar and common Comprised of a synovial joint which contains synovial cavity lined with a synovial membrane separating articulating bones Associated synovial joint structures Cartilages - Cushion the joint (Fibrocartilage- meniscus) Fat Pads - Superficial to joint capsule; Protect articular cartilages Ligaments - Support, strengthen joints Sprain – ligaments with torn collagen fibers Tendons - Attach to muscles around joint- Help support joint Bursae - where two body parts move against one another and THERE IS NO JOINT TO REDUCE THE FRICTION Ex: Cushion areas where tendons or ligaments rub against skin or bone Pockets of synovial fluid Bursitis: Inflammation of the bursae

11 Articular cartilages: Hyaline cartilage
Prevent bones from touching and grinding against one another Remnant of endochondral bone formation. Absorbs compression

12 Articular (joint) Capsule
Encloses the synovial cavity, unites the articulating bones. Has two parts: fibrous capsule and synovial membrane. Fibrous outer capsule - dense irregular connective tissue; tough but flexible. Synovial inner membrane made of areolar connective tissue w/ elastic fibers and adipose Membrane fibroblasts secrete synovial fluid from filtration of blood flowing thru capillaries Fluid has “egg white” consistency; hyaluronic acid is formed in the synovial membrane cells. Thins as the fluid is warmed. Fills cavity- occupies all free spaces within the capsule Lubricates joint- “weeping lubrication” – movement of joint squeezes fluid in and out of cartilage Nourishes articular cartilages Contains phagocytes Exercise important component- warms fluid, movement enables articular cartilage to absorb nutrients and remove waste Shock absorption

13 Accessory Structures ACCESSORY LIGAMENTS
Extracapsular ligaments lie outside the articular capsule; joint articulation and stability Patellar ligament Intracapsular ligaments occur within the articular capsule. Provide stability but allow a larger range of motion Anterior cruciate ligament (ACL) Posterior cruciate ligament (PCL) Accessory Structures ARTICULAR DISCS (MENISCUS). Pads of fibrocartilage within the synovial joint. Contribute to congruence (how well bones fit together at the articulation and the closeness of the articulating elements.)

14 “Cracking” Sound in the Joint
When force is applied to a synovial joint it separates the articulating surfaces creating a reduction in pressure within the cavity.** In this low pressure atmosphere some of the dissolved gases present in the fluid (mostly nitrogen and CO2,) are released and form a bubble or cavity. The bubble collapses on itself resulting in a clicking or popping sound. This is known as cavitation. When joints move, tendon’s position changes and moves slightly out of place. Hear a snapping sound as the tendon returns to original position. Ligaments also tighten making a similar sound. **Separation increases volume lowers pressure –Boyles Law V P

15 Synovial Joints Classified by Dynamic Motion Linear movement (gliding)
Angular movement Rotation Classified by Planes (Axes) of Dynamic Motion Monaxial (1 axis) Biaxial (2 axes) Triaxial (3 axes) Specific categories of synovial joint movements based on its motion and plane Plane/gliding – monoaxial; linear Hinge – monoaxial; angular Pivot – monoaxial; rotation Condylar / Ellipsoid –biaxial; angular Saddle - biaxial; angular Ball & socket –triaxial; angular, rotation

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17 “MOVEMENT” of Synovial Joints
Gliding (Planar): Surface of one bone moves back and forth and side to side over a flat surface. Angular: Increase or decrease in the angle between bones Flexion/extension Hyperextension Abduction/adduction Circumduction Rotation (Pivot): Bone revolves around its own longitudinal axis Pronation/supination Special: occurring only at particular joints Inversion/eversion Dorsiflexion/plantar flexion Protraction/retraction Elevation/depression

18 MOVEMENT: I. Gliding/Planar
Surface of one bone moves back and forth and side to side over a flat surface. No angular or rotational motion Movements limited by tight joint capsules. Action of one joint is slight but combination of many joints allows for considerable movement

19 Increase or decrease in the angle between bones
Flexion: decrease in the angle between articulating bones Lateral flexion: bending at the waste sideways to either right or left. Occurs in the frontal plane at the intervertebral joints. Extension: increase in the angle between two articulating bones Lateral flexion Bends vertebral column from side to side MOVEMENT: II. Angular

20 II. Angular Hyperextension: continuation of extension beyond the anatomical position. Prevented at some joints by the shape of the articulating bones and the ligaments associated with the joint. Flexion, hyperextension and lateral flexion of vertebral column

21 II. Angular Abduction: movement of a bone AWAY from the midline.
Adduction: movement of a bone TOWARD the midline.

22 II. Angular No special joint category
Circumduction: movement of the distal end of a part of the body in a circle. Circular motion without rotation No special joint category

23 MOVEMENT: III. Rotation
A bone rotates around its own long axis. Relative to longitudinal axis of body. Occurs at pivot and ball-and-socket joints Medial rotation: (inward rotation) Rotates toward axis - midline MOVEMENT: III. Rotation Lateral rotation: anterior surface of a bone or a limb limb is turned away from the midline. Rotates away from axis Supination: movement of the forearm at the proximal and distal radioulnar joints so that the palm is turned anteriorly Pronation: movement at the same joints as in supination, but so that the distal end of the radius crosses over the distal end of the ulna and the palm is turned posteriorly

24 IV. Special Movements Inversion: movement of the soles medially at the intertarsal joints so that they face each other. Eversion: movement of the soles laterally at the intertarsal joints so that they face away from each other. Dorsiflexion: bending the foot superiorly at the ankle; lifting toes Plantar flexion: bending the foot at the ankle toward the plantar surface; pointing toes

25 IV. Special Movements Elevation/Depression: upward/downward movement of a body part. The jaw and the shoulders. Protraction/Retraction: movement anteriorly in transverse plane/return to anatomical position of a body part. Jaw, chest Opposition: movement of the thumb so that it touches the fingers.

26 Synovial Joint PLANES/AXIS
NON-AXIAL Gliding - Flattened/slightly curved faces- limited motion MONAXIAL - motion in one (1) planes Hinge- Angular motion in a single plane Pivot - Rotation only BIAXIAL -motion in two (2) planes Condylar – (oval articular face within a depression) Saddle -Two concave, straddled TRIAXIAL - motion in three (3) planes Ball-and-socket - Round articular face in a depression

27 CATEGORY: “PLANE” Non-axial Vertebral column Intercarpal joints
Intertarsal joints Clavicle/sternum

28 CATEGORY: Hinge Joint CATEGORY: Pivot Joint
Concave surface of one bone articulates with and fits into the convex surface of another bone. Monaxial- moves freely in one plane (angular) Flexion or extension Ex: Knee, elbow, ankle, joints. CATEGORY: Pivot Joint Round or pointed surface of one bone fits into a ring formed by another bone and a ligament. Bone spins on its longitudinal axis Rotation-- Monaxial atlanto-axial joint (“no” movement of head) Radioulnar jointt

29 CATEGORY: Condylar (Ellipsoid))
Oval-shaped condyle of a bone fits into an elliptical cavity of another bone Flexion, extension, adduction, abduction, Biaxial movement – moves in two planes wrist -radiocarpal joint Meta-carpophalangeal joint Meta-tarsophalangeal joint CATEGORY: Saddle Joint Articular bones are shaped like saddle and rider Flexion, extension, abduction, adduction Biaxial Examples: Trapezium of carpus - at the thumb Sternoclavicular joint

30 CATEGORY: Ball-and-Socket Joint
Ball-shaped surface of a bone fits into the cup-like depression of the second bone. Most moveable: Flexion, extension, abduction, adduction, rotation, circumduction. Triaxial Ex: Shoulder and hip joints The Shoulder Joint- glenohumeral joint Allows MORE MOTION; the LEAST STABLE Between head of humerus and glenoid cavity of scapula Shoulder Separation Dislocation of the shoulder joint Shoulder Muscles (Rotator Cuff) The Hip Joint - coxal joint Strong ball-and-socket diarthrosis Wide range of motion

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32 The Elbow Joint A stable hinge joint
With articulations involving humerus, radius, and ulna Major supporting structure: Biceps brachii muscle

33 The Knee Joint A complicated hinge joint
Transfers weight from femur to tibia Articulations of the knee joint Two femur–tibia articulations At medial and lateral condyles One between patella and patellar surface of femur Seven Major Supporting Ligaments Patellar ligament (anterior) Two popliteal ligaments (posterior) Anterior / posterior cruciate ligaments (inside joint capsule) Tibial collateral ligament (medial) Fibular collateral ligament (lateral) Good Animation:

34 Anterior Right Leg Posterior Right Leg

35 Intervertebral Articulations
C2 to L5 spinal vertebrae articulation Permit small movements associated with flexion and rotation of the vertebral column Intervertebral Ligaments Bind vertebrae together Stabilize the vertebral column Intervertebral Discs are pads of fibrocartilage used to separate vertebral bodies Damage to Discs Slipped disc Bulge in anulus fibrosus Invades vertebral canal Herniated disc Nucleus pulposus breaks through anulus fibrosus Presses on spinal cord or nerves

36 Synovial Joints Injuries Dislocation (luxation) Subluxation
Articulating surfaces FORCED OUT OF POSITION Damages articular cartilage, ligaments, joint capsule Subluxation A PARTIAL dislocation

37 Effects of Aging on Articulations
Degenerative Changes Arthritis All forms of rheumatism that damage articular cartilages of synovial joints Osteoarthritis Gouty arthritis Rheumatoid arthritis

38 “Allopurinal” used to treat condition
Osteoarthritis Caused by wear and tear of joint surfaces, or genetic factors affecting collagen formation Generally in people over age 60 Degeneration of cartilage, no involvement of synovial membrane After joint is stationary for a time, pain at first movement that diminishes with continued movement Gouty Arthritis Inability to convert uric acid (waste product of DNA and RNA metabolism) to urea results in urate crystals which build up in joints. As joint moves, bones rub against crystals damaging articular cartilages resulting in severe inflammation and pain. Form within synovial fluid Bones can fuse Occurs in middle-aged men with an abnormal gene Can result from diuretic medications “Allopurinal” used to treat condition

39 Rheumatoid Arthritis Autoimmune disorder where white blood cells attack articular cartilages Synovial membrane thickens and adheres to articular cartilages. Fluid accumulates in joint capsule leading to deterioration of cartilages. Joint begins to ossify. Inflammation, swelling , severe pain Deformation of extremities Steroids used to treat the inflammation.

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41 Other Disorders Lyme disease (Lyme arthritis) Bacterial infection transmitted by deer ticks. Common symptoms are rash, fevers, chills, headache, stiff neck. joint stiffness, joint pain. First associated with children in Lyme, Connecticut 1970. Joint stiffness and pain generally occur in the later stages of the disease and most often in one or both knees Ankylosing spondylitis (“ankylos” fused) (‘spondylos”-vertebrae) (“itis” - inflammation) Syndrome of unknown cause that affects joints between the vertebrae and between the sacrum and hip bone. Chronic inflammatory disease; treat with anti-inflammatory medications such as ibuprofen, physical therapy and in severe cases surgery. Ankle sprains – ligament collagen fibers become torn Most common joint to be sprained or fractured. Treatment includes “RICE”: rest, ice, compression, elevation. 41

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43 Aging and Joints Decreased production of synovial fluid
Thinning of articular cartilages Loss of ligament length and flexibility Arthroscopy: joint examination using instruments the size of a pencil that allows the use of tiny instruments and a tiny microscope. Small incision through which repairs can be made including removal of torn cartilages of the knee. Arthroplasty: replacement of a joint. Hip, knee and shoulder are commonly replaced. Articular elements are replaced by plastic/stainless steel. 43

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