Chapter 9 - Articulations

Chapter 9 - Articulations - KIN 216 Applied Human Anatomy...

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Unformatted text preview: KIN 216 Applied Human Anatomy Chapter 9 Articulations Arthro (Gr.) = joint Articulations and skeletal contractions allow movement Arthrology = the study of joints Arthralgia: pain in joints Joints are classified by function or structure Functional classification of joints Synarthroses (immovable) Amphiarthroses (slightly movable) Diarthroses (freely movable) Articulations (2) Structural classification of joints Fibrous Cartilaginous Have bones connected by dense fibrous CT No joint capsule Range from immovable to slightly moveable Sutures, syndesmoses, and gomphoses Have bones connected by cartilage No joint capsule Allow limited movement (twisting, compression) Synchondroses and symphyses Synovial Have a joint capsule Allow different types of movement Classified by shape (more on this later) Fibrous Joints Sutures ("seams") Only between skull bones Edges of joining bones are wavy and interlocking Form at about age 18 months (when you are younger than that, joints are called fontanels) When you reach adult status, sutural joints completely ossify, then called SYNOSTOSIS Fibrous Joints (2) Syndesmoses Fibrous joints held together by ligaments Desm = ligament No joint capsule Slight movement (amount of movement depends on length of connecting fibers) Ex: distal tibiofibular joint Gomphoses Occur between teeth and jaw ("peg-insocket") Cartilaginous Joints Synchondroses Hyaline cartilage between articulating bones Some are temporary (ex- growth plate) and ossify later (also called synostosis) Symphyses Joined by fibrocartilage Provides cushioning, allows limited movement Ex. Pubic symphysis, intervertebral joints Synovial Joints Freely moveable, enclosed by joint capsule Function: allow movement and provide stability (not able to have the best of both worlds, though) Range of motion Amount of movement allowed at a joint Determined by bone structure, characteristics of connective tissue, muscles around joint Features of Synovial Joints: Articular cartilage Joint cavity Hyaline cartilage around ends of bone, poorly vascularized Space that holds synovial fluid Joint capsule (articular capsule) Outer covering (fibrous capsule) = dense irregular CT, continuous with periosteum Synovial membrane Makes synovial fluid, which nourishes and lubricates joint Inner lining = loose/areolar CT General Features of Synovial Joints (2) Synovial fluid Ligaments Fluid is similar to interstitial fluid (betw. cells) filtrate of blood, contains a type of acid and protein, as well as phagocytic cells to clean up tissue debris Glycoproteins are secreted by fibroblasts, make fluid slippery Mostly inside capsule; sometimes outside of capsule Nerves and blood vessels Many sensory nerve fibers (sense stretch) Rich blood supply (make synovial fluid) General Features of Synovial Joints (3) The following features are NOT found in ALL synovial joints, but can be present Articular disc (meniscus) Found only in certain joints whose articulating bone ends have different shapes Bursae Contains synovial fluid Is like a closed bag reduces friction Tendon sheaths Elongated bursa that wraps around tendon reduces friction Movements of Synovial Joints 3 types of movement: gliding, angular, and rotation Gliding Simplest type of joint movement Allow side-to-side and back & forth movements Articular surfaces are relatively flat (but may have one concave and one convex surface as well) Ex: intercarpals Movements of Synovial Joints (2) Angular movements Increase or decrease joint angle Five movements (flexion, extension, abduction, adduction, circumduction) Flexion Decreases joint angle in antero-posterior plane Ex: bending elbow, knee NOTE that ankle and shoulder are kind of strange: at ankle, dorsiflexion is lifting up toes, plantarflexion is pointing toes; at shoulder, pointing forward is flexion Extension Reverse of flexion, returns body part to anatomical position Joint angle is increased (usually to 180 degrees, except at ankle- 90 degrees) Hyperextension: increase in joint angle beyond normal range Movements of Synovial Joints (3) Angular movements (contd) Abduction Movement away from main axis of body in lateral direction NOTE: bending trunk to right or left is called lateral flexion Adduction Movement towards the body midline, opposite of abduction Proximal end is fixed, distal end performs circular movement (traces cone-shape path) Circumduction Movements of Synovial Joints (4) Rotation Special movements Movement of body part around its own axis (medial or lateral) Ex: shaking head ,,no Pronation and supination are specialized forms of rotation of the forearm Inversion and eversion Supination = palm up, pronation = palm down Inversion = turn sole medially, eversion = turn sole laterally Protraction = in anterior direction, retraction = in posterior direction Protraction and retraction Movements of Synovial Joints (5) Special movements (contd) Plantar flexion and dorsiflexion (see previous slide) Elevation and depression = lifting superiorly, depression = moving inferiorly Ex: mandible during chewing Elevation Opposition movement by saddle joint (thumb carpals and metacarpal 1) Thumb touches tips of other fingers on same hand Special Synovial Joints Classified by Shape Plane, hinge, pivot, condyloid, saddle, ball-and-socket Plane Simplest type of joint movement Allow side-to-side and back & forth movements Articular surfaces are relatively flat (but may have one concave and one convex surface as well) Ex: Intercarpals Synovial Joints Classified by Shape (2) Hinge Have one axis (uniaxial), similar to door hinge Allow movement in only one plane Articular surfaces are rounded (one surface concave, other convex) Ex: elbow, knee, interphalangeal Pivot Performs rotation around a central axis (uniaxial) Surface of one bone is conical (cone) or rounded, and it fits into a depression on the other bone also has encircling ligament Ex: proximal radioulnar joint (head of radius is secured by ring-like ligament to ulna) Synovial Joints Classified by Shape (3) Condyloid Very similar to hinge but have 2 axes (biaxial) An oval, convex surface (egg shape) of one bone fits into a concave depression on the other bone Permits movements both back and forth and side to side Ex: metacarpophalangeal joints Saddle Special type of condyloid joint Each articular process has a concave surface in one direction and convex in the other direction Allows quite a bit of movement Ex: thumb (where trapezius meets 1st metacarpal bone) Synovial Joints Classified by Shape (4) Ball and socket Rounded convex surface with a cuplike cavity Multiaxial (all axes, including rotation) greatest range of motion of all synovial joints Ex: hip and shoulder In hip, the ball is on the femur and the socket is part of the os coxa, specifically the ischium- socket is called acetabulum) In shoulder, ball is on humerus and socket on scapula- called glenoid cavity) The Knee Joint complex joint in the body Acts mostly as a hinge joint Allows some medial and lateral rotation too Most surfaces on femur (rounder) and tibia (more flat) femur rolls along tibia Femoropatellar joint also present Synovial joint Condylar Knee Joint (2) Complex shape of synovial cavity Many bursae 2 menisci (fibrocartilage), c- shape Lateral and medial, attach to tibias condyles No capsule on anterior side; instead there is the patellar ligament and medial & lateral retinacula Patellar tendon connects quadriceps to patella Knee Joint Ligaments Extracapsular Fibular (lateral) collateral ligament From lateral epicondyle of femur to head of fibula medial epicondyle of femur to medial condyle of tibia Tibial (medial) collateral ligament From Knee Joint Ligaments (2) Intracapsular Attaches ligaments Anterior cruciate ligament (ACL) to anterior portion of tibia and medial side of lateral condyle of femur Prevents anterior sliding of tibia Posterior cruciate ligament (PCL) to posterior portion of tibia and lateral side of medial condyle Prevents forward sliding of femur and/or posterior sliding of tibia Attaches Disorders of Joints Injuries Sprains Ligaments are stretched or torn Dislocations (luxation) Bones of joint are forced out of alignment Subluxation: partial or incomplete dislocation Most often meniscus of knee but also occurs in other joint cartilages Difficult to heal due to avascularity Torn cartilage Inflammatory and degenerative conditions Bursitis and tendinitis Bursitis = inflammation of bursa Tendinitis = inflammation of tendon sheaths Disorders of Joints (2) Inflammatory and degenerative conditions (contd) Arthritis Over 100 kinds of inflammatory or degenerative diseases Osteoarthritis Most common; chronic degenerative condition no known cause (aging process) Chronic inflammatory disorder; autoimmune disease (cause unknown) Occurs if someone isnt excreting enough uric acid in urine acid forms crystals Inflammatory response to crystals occurs; body tries to rid itself of crystals Rheumatoid arthritis Gouty arthritis ...
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