Chapter 9 - anatomy and physiology PDF

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Chapter 9: Joints An Introduction to Joints: Joints (articulations) • •

Where two bones meet Where body movement occurs

A tradeoff exists between strength and mobility Two classification schemes • •

Structural (anatomy) Functional (range of motion)

Joint structure determines function

9-1 Classification of Joints: Structural classifications • • • •

Fibrous Cartilaginous Bony Synovial

Functional classifications • • •

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

Synarthrosis (immovable joint)

-Very strong -Edges of bones may touch or interlock -May be fibrous or cartilaginous -Four types of synarthrotic joints: • Suture: Found only between bones of skull Edges of bones interlock Bound by dense fibrous connective tissue Gomphosis: Binds teeth to bony sockets Fibrous connection (periodontal ligament)

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Synchondrosis: Rigid cartilaginous bridge between two bones Found between vertebrosternal ribs and sternum Also, epiphyseal cartilage of growing long bones

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Synostosis: Created when two bones fuse Example: metopic suture of frontal bone And epiphyseal lines of mature long bones

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Amphiarthrosis

-More movable than a synarthrosis -Stronger than a diarthrosis -May be fibrous or cartilaginous -Two types of amphiarthroses • Syndesmosis—bones connected by a ligament • Symphysis—bones connected by fibrocartilage

Synovial joints (diarthroses)

9-2 Synovial Joints: Figure 9–1a The Structure of a Synovial Joint, Figure 9–1b The Structure of a Synovial Joint. Synovial joints (diarthroses) Freely movable joints At ends of long bones Surrounded by joint capsule (articular capsule) o Contains synovial membrane Synovial fluid from synovial membrane o Fills joint cavity Articular cartilage covers articulating surfaces o Prevents direct contact between bones

Synovial fluid Has the consistency of egg yolk Contains proteoglycans Primary functions include o Lubrication o Nutrient distribution o Shock absorption Synovial joints are mobile but relatively weak Stabilized by accessory structures o o o o

Cartilages and fat pads Ligaments Tendons Bursae

Cartilages Meniscus—fibrocartilage pad between opposing bones Fat pads Adipose tissue covered by synovial membrane Protect articular cartilages

Ligaments Support and strengthen joints Sprain—ligament with torn collagen fibers

Tendons Attach to muscles around joint

Bursae Small pockets of synovial fluid Cushion areas where tendons or ligaments rub against other tissues

Factors that stabilize synovial joints o o o o o

Prevent injury by limiting range of motion Collagen fibers of joint capsule and ligaments Shapes of articulating surfaces and menisci Other bones, muscles, or fat pads Tendons attached to articulating bones

9-3 Movements at Synovial Joints: Movements are described in terms that reflect the o Plane or direction of movement o Relationship between structures

Planes of movement o Monaxial—1 plane (e.g., elbow) o Biaxial—2 planes (e.g., wrist) o Triaxial—3 planes (e.g., shoulder) Types of movement at synovial joints o o o o o

Gliding movement Angular movement Circumduction Rotational movement Special movements

Gliding movement When two flat surfaces slide past each other Example: between carpal bones Angular movement ( Figure 9–3a ,bAngular Movements and Circumduction) -Flexion and extension are movements in the anterior–posterior plane -Flexion • Decreases angle between articulating bones -Extension • Increases angle between articulating bones -Hyperextension • Extension past anatomical position -Abduction and adduction are movements in the frontal plane -Abduction • Movement away from longitudinal axis -Adduction • Movement toward longitudinal axis Circumduction Figure 9–3c,d Angular Movements and Circumduction. -A complete circular movement without rotation Rotational movement: Figure 9–4a,b Rotational Movements. -Rotation in reference to anatomical position • Example: left or right rotation of head -Limb rotation is relative to longitudinal axis of body • Medial rotation (internal rotation toward long axis) • Lateral rotation (external rotation away from body -Pronation • Rotates forearm so that radius rolls across ulna • Results in palm facing posteriorly -Supination

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Turns palm anteriorly Forearm is supinated in anatomical position

Special movements: Figure 9–5a ,b,c, d,e ,f Special Movements. Inversion • Twists sole of foot medially -Eversion • Twists sole of foot laterally -Dorsiflexion • Flexion at ankle (lifting toes) -Plantar flexion • Extension at ankle (pointing toes) -Opposition • Movement of thumb toward palm or other fingers -Reposition • Opposite of opposition -Protraction • Anterior movement in horizontal plane (forward) -Retraction • Opposite of protraction (pulling back) -Depression • Moving a structure inferiorly (down) -Elevation • Moving a structure superiorly (up) -Lateral flexion • Bending vertebral column to the side

Classification of synovial joints: Figure 9–2 Joint Movement (Part 8 of 12). o o o o o o

Plane (gliding) Hinge Condylar (ellipsoid) Saddle Pivot Ball-and-socket

9-4 Intervertebral Joints Structure : First two cervical vertebrae are joined by a synovial joint Synovial joints lie between adjacent articular processes

Adjacent vertebral bodies form symphyses Intervertebral disc: o Separates vertebral bodies o Anulus fibrosus a.Tough outer layer of fibrocartilage b.Attaches disc to vertebrae o Nucleus pulposus a.Elastic, gelatinous core b.Absorbs shocks o Vertebral end plates of cartilage Cover superior and inferior surfaces of disc ~Damage to intervertebral discs: Clinical Note 9-1a,b Damage to Intervertebral Discs. o Bulging disc i. Bulge in anulus fibrosus ii. Invades vertebral canal o Herniated disc i. Nucleus pulposus breaks through anulus fibrosus ii. Compresses spinal nerves ~As vertebral column moves o Nucleus pulposus compresses o Disc shape conforms to motion Intervertebral ligaments o Bind vertebrae together o Stabilize the vertebral column Figure 9–6a Intervertebral Joints. 1.Ligamenta flava o Connect laminae of adjacent vertebrae 2.Posterior longitudinal ligament o Connects posterior surfaces of vertebral bodies 3.Anterior longitudinal ligament o Connects anterior surfaces of vertebral bodies

4.nterspinous ligaments o Connect spinous processes of adjacent vertebrae 5.Supraspinous ligament o Connects tips of spinous processes (C7 to sacrum) o Continuous with ligamentum nuchae (C7 to skull) Vertebral movements Flexion Extension Lateral flexion Rotation

9-5 Elbow and Knee Joints: Elbow joint: Figure 9–7a,b The Right Elbow Joint Showing Stabilizing Ligaments. Hinge joint Articulations involve humerus, radius, and ulna Structures of the elbow o Biceps brachii muscle i. Attaches to radial tuberosity ii. Controls elbow motion o Elbow ligaments i. Radial collateral ii. Anular iii. Ulnar collateral Knee joint Complex hinge joint Transfers weight from femur to tibia Three articulations o Two femur–tibia articulations: At medial and lateral condyles o One between patella and patellar surface of femur ~Joint capsule and joint cavity of knee Medial and lateral menisci o Fibrocartilage pads

o At femur–tibia articulations o Cushion and stabilize joint ~Seven major supporting ligaments: Figure 9–8a,b,c,d The Right Knee Joint. 1.Patellar ligament (anterior) 2. & 3. Two popliteal ligaments (posterior) 4. & 5. Anterior and posterior cruciate ligaments: (inside joint capsule) 6. & 7. Tibial collateral ligament (medial) and fibular collateral ligament (lateral)

9-6 Shoulder and Hip Joints: Shoulder joint (glenohumeral joint) Ball-and-socket diarthrosis Between head of humerus and glenoid cavity of scapula Greatest range of motion of any joint Most frequently dislocated joint Supported by skeletal muscles, tendons, and ligaments 1.Joint capsule and joint cavity of shoulder Glenoid labrum o Rim of fibrocartilage o Extends beyond bony rim and deepens socket of glenoid cavity Acromion and coracoid process of scapula o Project laterally, superior to humerus o Help stabilize the joint Shoulder ligaments: Figure 9–9a,b The Shoulder Joint. o o o o o

Acromioclavicular Coracoclavicular Coraco-acromial Coracohumeral Glenohumeral

Shoulder separation o Partial or complete dislocation of acromioclavicular joint 2.Hip joint Between head of femur and acetabulum of hip bone

Strong ball-and-socket diarthrosis Wide range of motion Acetabular labrum o Rim of fibrocartilage o Increases depth of joint cavity o Seals in synovial fluid Ligaments of the hip joint: Figure 9–10a The Right Hip Joint o o o o o

Iliofemoral Pubofemoral Ischiofemoral Transverse acetabular Ligament of the femoral head

9-7 Effects of Aging on Joints Degenerative changes •

Rheumatism Pain and stiffness in musculoskeletal system

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Arthritis (joint inflammation) All rheumatic diseases that affect synovial joints

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Osteoarthritis Caused by wear and tear of joint surfaces, or genetic factors affecting collagen formation Generally affects people over age 60

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Rheumatoid arthritis An inflammatory condition Immune system attacks joint tissues

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Gouty arthritis Crystals of uric acid form within synovial fluid

Can be caused from joint immobilization • • •

Reduces flow of synovial fluid Can cause symptoms of arthritis Treated by continuous passive motion (CPM)

As we age • • •

Bone mass decreases Bones weaken Risk of fractures increases

9-8 Integration with Other Systems: Figure 9–11 Integration of the SKELETAL system with the other body systems presented so far. Living bones undergo remodeling that involves o Bone formation (osteoblasts) o And bone recycling (osteoclasts) Other systems interact with the skeletal system o Muscles attach to bones o Bones are controlled by endocrine system o Digestive and urinary systems provide calcium and phosphate minerals to bones for growth o Skeleton serves as a reserve for calcium, phosphate, and other minerals...