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Chapter 9 Joints.

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Presentation on theme: "Chapter 9 Joints."— Presentation transcript:

1 Chapter 9 Joints

2 INTRODUCTION Joint = point of contact between 2 bones
between cartilage and bone between teeth and bone Joints hold bones together but permit movement Arthrology = study of joints Kinesiology = study of motion

3 I. Classification of Joints
Structural classification based on: presence or absence of a synovial (joint) cavity type of connective tissue three structural classifications fibrous do not have synovial cavity held together by fibrous C.T. (lots of collagen) cartilaginous no synovial cavity bones held together by cartilage synovial bones forming joint have a synovial cavity dense irreg. C.T. & accessory ligaments of articular capsule holds bones together

4 I. Classification of Joints
Functional classification based on degree of movement allowed by joint: Synarthrosis = immovable Amphiarthrosis = slightly movable Diarthrosis = freely movable

5 II. A. Fibrous Joints No synovial cavity
Articulating bones held closely together by fibrous C.T. Allow limited movement 3 structural types sutures syndesmoses gomphoses

6 Sutures Thin layer of dense fibrous connective tissue uniting bones of the skull Irregular/interlocking edges give added strength & prevent fracture Synarthrosis because immovable Synostosis = suture that has fused completely & been replaced by bone

7 Syndesmoses Greater distance btwn articulating bones & more fibrous C.T. than sutures Arrangements of C.T. bundles = ligament sheets = inteross. memb. Amphiarthrosis: limited movement Examples Anterior tibiofibular joint Interosseous membranes in forearm and leg

8 Gomphoses Dentoalveolar joints: cone-shaped pegs in bony socket
Synarthrosis Only example = teeth in alveolar processes of maxillae and mandible

9 B. Cartilaginous Joints
Lack a synovial cavity Allows limited movement Articulating bones tightly connected by fibrocartilage or hyaline cartilage 2 types synchondroses symphyses

10 Synchondrosis Connecting material = hyaline cartilage Synarthrosis
Examples: epiphyseal plates articulation of first rib w/ manubrium of sternum become synostoses when bone replaces cartilage

11 Symphysis Ends of articulating bones covered w/ hyaline cartilage
Thin disc of fibrocart. connects bones All occur in midline of body Amphiarthrosis Examples: intervertebral disc pubic symphysis

12 C. Synovial Joints Synovial cavity separates articulating bones
Freely moveable (diarthroses) Articular cartilage covers articulating bones reduces friction absorbs shock Three structural components: Articular capsule Synovial membrane/fluid Accessory ligaments/discs

13 Structural Components: Articular Capsule
Surrounds joint, encloses synovial cavity, & unites articulating bones Two layers outer fibrous capsule usually dense irregular C.T. attaches periosteum of articulating bones flexibility permits considerable movement, but tensile strength prevents dislocation forms ligaments (dense CT) when arranged in bundles inner synovial membrane secretes a lubricating synovial fluid sometimes contains articular fat pads EX: infrapatellar fat pads

14 Structural Components, ctd
Synovial fluid Mixture of hyaluronic acid secreted by synovial membrane & interstitial fluid Lubricates joints & absorbs shock Provides nutrients to/removes wastes from articular capsule Phagocytes remove microbes Immobility of joint increases viscosity, activity decreases viscosity

15 Structural Components, ctd
Accessory ligaments & articular discs/menisci extracapsular ligaments lie outside joint capsule intracapsular ligaments lie within capsule articular discs (menisci) = pads of fibrocartilage btwn bones attached to capsule allow 2 bones of different shape to fit tightly maintain stability of joint

16 Nerve and Blood Supply of Synovial Joints
Nerves to joints are branches of nerves that supply muscles that move joint Many nerve endings distributed to articular capsule & accessory ligaments sense pain relay information about degree of stretch/movement Many components are avascular but arteries can penetrate ligaments/capsule deliver nutrients to joint veins remove CO2 & wastes pass from chondrocytes to synovial fluid to vein pass directly from all other joint structure to vein

17 Bursae and Tendon Sheaths
Fluid-filled saclike structures that alleviate friction in some joints Resemble joint capsules Walls consist of C.T. & synovial membrane Fluid similar to synovial fluid Located between: Skin/bone Tendon/bone or ligament/bone Muscle/bone Bursitis = chronic inflammation of a bursa

18 Bursae and Tendon Sheaths
Tendon sheaths = tubelike bursae that wrap around tendons that experience large amounts of friction where tendon enters synovial cavity Biceps shoulder where many tendons come together in small space Wrist/ankle where there is considerable movement Fingers/toes Bursae & tendon sheaths reinforce the articular capsule

19 Types of Movements at Synovial Joints
Four main categories of joint movement (Table 9.1) Gliding movements flat bone surfaces move back and forth & side to side with respect to one another no significant alteration of angle between bones limited in range because of structure of capsule/ligaments Ex: intercarpal or intertarsal joints (planar joints)

20 Types of Movements at Synovial Joints
Angular movements Increase or decrease in angle btwn articulating bones Measured with respect to anatomical position Covered in lab Flexion/extension, lateral extension, hyperextension Abduction/adduction, circumduction

21 Types of Movements at Synovial Joints
Special movements Occur only at certain joints 11 different special movements Elevation/depression: upward/downward motion Protraction/retraction: movement in transverse plane Inversion/eversion: movement of soles medially/laterally Dorsiflextion/plantarflexion: bending of ankle in direction of superior/inferior surfaces Supination/pronation: movement of prox/distal radioulnar joints which turns palms anteriorly/posteriorly Opposition: movement of carpometacarpal joint in which thumb touches fingers of same hand

22 Types of Synovial Joints
***These will be covered in lab, so they will be minimally discussed in lecture. However the notes may be useful to you in studying for the lab exam.*** Varying shapes of bones/joints allow numerous movements 6 types Planar Hinge Pivot Condyloid Saddle Ball & socket

23 1. Planar Joint Articulating surfaces flat or slightly curved
Primarily allow gliding movements Rotation prevented by ligaments Nonaxial because motion does not occur around axis or along plane Examples intercarpal or intertarsal joints sternoclavicular joint vertebrocostal joints

24 2. Hinge Joint Convex surface of one bone fits into concave surface of another Monaxial: allows motion around single axis produces angular opening & closing flexion/extension only Examples Knee, elbow, interphalangeal joints

25 3. Pivot Joint Rounded/pointed surface of bone articulates with ring formed by 2nd bone & ligament Monaxial: rotation around own axis Examples Proximal radioulnar joint supination pronation Atlanto-axial joint nodding head “no”

26 4. Condyloid (Ellipsoidal) Joint
Convex oval-shaped projection articulates with oval depression Biaxial: allows motion along two axes flexion/extension abduction/adduction/circumduction Examples: wrist & metacarpophalangeal joints for digits 2 to 5

27 5. Saddle Joint Articulating surface of one bone saddled-shaped; other bone fits into “saddle” Modified condyloid joint Biaxial Circumduction allows tip of thumb travel in circle Opposition allows tip of thumb to touch tip of other fingers Example: carpo/metacarpal joint of wrist/thumb

28 6. Ball and Socket Joint Ball-like head of long bone fits into a cup-like socket Multiaxial: motion around 3 axes & all directions in between flexion/extension abduction/adduction rotation Examples: shoulder joint: humerus in glenoid hip joint: femur in acetabulum

Range of motion (ROM) = range (measured in degrees of circle) thru which bones of joint can move Several factors contribute to keeping articular surfaces in contact & affect ROM: Structure and shape of the articulating bone Strength and tautness of the joint ligaments Arrangement and tension of the muscles Contact of soft parts Hormones Disuse

30 IV. ETC… Arthroscopy = examination of joint w/ pencil-sized instrument
removes torn knee cartilages & repair ligaments requires only small incision Arthroplasty = joint replacement hip & knee replacements common Dislocation of a joint = luxation refers to displacement of a bone from a joint torn tendons, ligaments, capsules accompany dislocation subluxation = partial dislocation

31 ETC… Sprain forcible twisting of joint that stretches or tears ligaments no dislocation of the bones may damage nearby blood vessels, muscles or tendons or nerves swelling & hemorrhage from damaged blood vessels ankle & back are common sprain sites Strain overstretched or partially torn muscle results from sudden, powerful contraction

Osteoarthritis degenerative joint disease commonly known as “wear-and-tear” arthritis characterized by deterioration of articular cartilage and bone spur formation noninflammatory primarily affects weight-bearing joints Gouty arthritis sodium urate crystals deposited in soft tissues of joints causing inflammation, swelling, and pain If not treated, affected joints eventually fuse, rendering joints immobile

33 Rheumatoid Arthritis Autoimmune disorder: body attacks its own cartilage & joint linings Inflammation of synovial membrane accumulation of synovial fluid causes swelling, pain & loss of function eventually, fibrous tissue in joints becomes ossified  joint becomes immovable Occurs bilaterally

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