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Chapter 8 Joints of the Skeletal System. Classification of Joints.

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Presentation on theme: "Chapter 8 Joints of the Skeletal System. Classification of Joints."— Presentation transcript:

1 Chapter 8 Joints of the Skeletal System

2 Classification of Joints

3 Joints of the Skeletal System Articulations Functional junctions between bones Bind parts of skeletal system together Make bone growth possible Permit parts of the skeleton to change shape during childbirth Enable body to move in response to skeletal muscle contraction

4 Functional Classification Of Joints Classification=based on the amount of movement allowed 3 types: Synarthroses = immovable joints –Example = sutures of skull Amphiarthroses = slightly movable joints. –Example = intervertebral discs between vertebrae Diarthroses = freely movable joints –Examples = joints of appendicular skeleton

5 Structural Classification Of Joints Classification= Based on material, which joins bones 3 types: –Fibrous –Cartilaginous –Synovial

6 Fibrous Joints joints composed of fibrous tissue no joint cavity is present 3 types: –Syndesmosis –Suture –Gomphosis

7 Fibrous Joints cont. Syndesmosis = cord of fibrous tissue called a ligament –amphiarthroses with "give" but no true movement –Example = distal tibiofibular joint

8 Fibrous Joints cont. Sutures = short fibrous CT fibers –synarthroses –Only found in skull

9 Fibrous Joints cont. Gomphosis = tooth within its bony socket (alveolar fossa) –short periodontal ligament

10 Cartilaginous Joints joints composed of cartilage no joint cavity 2 types: –Synchondrosis –Symphysis

11 Cartilaginous Joints cont. Synchondrosis = a plate of hyaline cartilage –sites of bone growth during youth –eventually ossify = synarthrotic –Examples: joint between the first rib and manubrium and the epiphyseal plate

12 Cartilaginous Joints cont. Symphysis = pad or plate of fibrocartilage –compressible "shock absorber" –limited movement = amphiarthroses –Examples: intervertebral discs and symphysis pubis

13 Synovial Joints = fluid-filled joint cavity – free movement = diarthrosis

14 General Structure Of A Synovial Joint General Structure Of A Synovial Joint = 5 distinct features: 1. Articular cartilage = hyaline cartilage covers the surface of each bone 2. Joint cavity = a potential space between the two bones, filled with synovial fluid 3. Synovial fluid = viscous lubricating fluid within cavity –reduces friction between cartilages of 2 bones provide lubrication nourish cartilage contain phagocytes

15 Synovial Joints cont. 4. Articular capsule = double layered capsule surrounding cavity: –External, tough flexible fibrous capsule (continuous with periosteum of the bones) –Synovial membrane = loose CT lining of fibrous capsule, that also covers all internal joint surfaces excluding hyaline cartilage 5. Reinforcing ligaments = ligaments that strengthen joint –Definition: A ligament joins a bone to another bone across a synovial joint –usually thickened portions of fibrous capsule (intrinsic or capsular)

16 General Structure of a Synovial Joint

17 Synovial Joints cont. Other joint features: fatty pads (hip & knee) menisci or articular discs or that separate cavity into 2 compartments (knee, jaw, sternoclavicular)

18 Synovial Joints cont. bursa = flattened fibrous sacs with a synovial membrane and fluid that act as "ball bearings" to prevent friction on adjacent structures during joint activity –cushion the movement of one body part over another; –located between skin and bone (where skin rubs over bone), and between muscle, tendons, ligaments and bone.

19 Types Of Synovial Joints Ball-and-socket joints = most freely movable joints; all angular movement –The head of one bone fits into the socket of another –Examples = hip and shoulder Condyloid joints = permit all angular motion, except rotation –Examples = wrists and knuckles

20 Types Of Synovial Joints cont. Gliding joints = cartilaginous joints –Example = intervertebral discs Hinge joints = permit flexion & extension only –Examples = elbow and knee

21 Types Of Synovial Joints cont. Pivot joints = permit rotation –Example = first intervertebral joint (atlantoaxial joint) Saddle joints = thumb

22 Types Of Joint Movements

23 Introduction Origin = part of muscle attached to the immovable bone Insertion = part of a muscle attached to the movable bone When a muscle contracts across a joint, its insertion is pulled toward its origin

24 Three general types of movement Gliding movements = when flat bone surfaces glide or slide over one another –occur at cartilaginous joints –Examples = intervertebral discs and sternoclavicular joints Angular movements = changes in angles between bones –occur only at synovial joints


26 Movement cont. Flexion = decreasing the angle between 2 bones. –Example = head toward chest –Dorsiflexion = bringing foot closer to shin –Plantar flexion = pointing one's toe (flexion toward the sole) Extension = increasing the angle between 2 bones –Example = straightening a flexed neck –Hyperextension = increasing the angle greater than 180o


28 Movement cont. Abduction = moving a limb away from the midline. –Example = raising arm or thigh laterally; Adduction = moving a limb toward the midline


30 Movement cont. Circumduction = moving a limb in a circular (cone-shaped) manner Rotation = turning movement of a bone along its long axis. –Example = atlas over axis (i.e. “just say no”) –Example = shoulder and hip joint


32 Special Movements Special Movements = those at specific joints supination/pronation = movements between the radius and ulna at the proximal radioulnar joint –thumb up = supination –thumb down = pronation inversion/eversion = movement of foot –sole inward = inversion –sole out = eversion


34 Special Movements cont. elevation/depression –shoulder shrug = elevation –mandible in opening mouth = depression protraction/retraction –thrust forward = protraction –pull back = retraction


36 Shoulder joint Shoulder joint (2 joints) Ball and socket is the glenohumeral joint –joins Glenoid cavity and head of humerus Syndesmosis is called the acromioclavicular joint –acromial end of clavicle and the acromion process of the scapula Ball and socket is surrounded by many reinforcing ligaments and tendons collectively called the rotator cuff Many bursa also lubricate the shoulder Movement can occur in any angular plane


38 Elbow joint (2 joints) Hinge is between trochlea of humerus and trochlear notch of ulna Gliding joint is between capitulum of humerus and head of radius Very stable joint with many reinforcing ligaments Only allows flexion and extension


40 Hip joint (coxal joint) Ball and socket between head of femur and acetabulum of coxa Contains many large reinforcing ligaments Allows same movements as shoulder, but with less range due to bony limitations


42 Knee (3 joints) Largest, most complex joint –Functions as a hinge even though 3 joints work together Medial condyles of femur and tibia make one condyloid joint Lateral condyles of femur and tibia make another condyloid joint Patellar surface of femur and patella make a gliding joint –Flexion and extension with some slight rotation –Contains many reinforcing structures

43 Knee cont. Menisci –medial meniscus –lateral meniscus C-shaped fibrocartilage pads –Reshape the tibial condyles for a better fit –Absorb shock –Many bursae


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