A&P Outline 8: Chapter 9; Articulations PDF

Outline 8: Chapter 9; Articulations I. Introduction A) Articulation = joint = where 2 bones interconnect -structure determines type & amount of movement (range of motion) -NOTE: joint strength decreases as mobility increases II. Joints A) Classification...

Outline 8: Chapter 9; Articulations I. Introduction A) Articulation = joint = where 2 bones interconnect -structure determines type & amount of movement (range of motion) -NOTE: joint strength decreases as mobility increases II. Joints A) Classification -2 methods 1) functional classification: based on range of motion 2) structural classification: relies on anatomical organization B) Functional Classification 1)types in general a) synarthrosis = immovable -may be a fibrous or cartilaginous connection b) amphiarthrosis = little movement -may be a fibrous or cartilaginous connection c) diarthrosis = freely movable -also called a synovial joint C) Structural Classification 1) General -joint name typically derived from names of bones involved -joints classified according to how bones are bound together -4 categories: bony, fibrous, cartilaginous, and synovial 2) Bony Joints a) synostosis i. immobile -formed when the gap between two bones ossifies, and the bones become a single bone ii. examples: -left and right mandibular bones in infants -cranial sutures in elderly -attachment of first rib and sternum with old age iii. can occur in either fibrous or cartilaginous joint 3) Fibrous joint (synarthrosis) a) adjacent bones bound by collagen fibers -emerge from one bone and penetrate into the other  b) types i. suture (synarthrosis) -immobile or slightly fibrous joints in which short collagen fibers bind the bones of the skull to each other ii. gomphoses (fibrous joint, synarthrotic) -attachment of a tooth to its socket -held in place by fibrous periodontal ligament -collagen fibers attach tooth to jawbone -allows tooth to move a little under stress of chewing iii. syndesmosis -fibrous joint at which two bones are bound by long collagen fibers -example of very mobile: interosseous membrane joining radius to ulna allowing supination and pronation -example of less mobile: joint between tibia and fibula 4) Cartilaginous joints a) amphiarthrosis -two bones are linked by cartilage b) types i. synchondrosis- bones joined by hyaline cartilage -temporary joints in the epiphyseal plate in children -bind epiphysis to diaphysis -first rib attachment to sternum -other costal cartilages joined to sternum by synovial joints ii. symphyses- two bones joined by fibrocartilage -pubic symphysis joins right and left pubic bones with interpubic disc -bodies of vertebrae joined by intervertebral discs -only slight movements between adjacent vertebrae 5) Diarthrosis = synovial joints a) features i. at ends of long bones ii. within articular capsules lined by synovial membrane (produces synovial fluid) iii. very mobile, but WEAKEST joint type b) components of synovial joint  i) articular cartilage = hyaline cart -provides smooth surface that helps reduce friction -no perichondrium (no BV’s so no repairing if damaged) -may become rough if matrix breaks down (arthritis) ii. synovial fluid: about 3ml -separates articular cartilage -reduces friction and shock -lubricates joint -nourishes chondrocytes of articular cartilage & removes wastes c) accessory structures i. cartilages 1. meniscus (articular disc) -fibrous cartilage pads -helps channel flow of synovial fluid -allows for variation in articular surfaces 2. articular cartilage -cushions bones ii. fat pads = masses of adipose tissue 1. superficial to joint capsule 2. protect articular cartilages 3. fills cavity as shape changes iii. ligaments (bone to bone) -supports & strengthens joint -can be intracapsular or extracapsular -sprain = ligaments with torn collagen fibers -bones will break before ligament tears (better because bones heal quicker) iv. tendons (muscle to bone) -attach to muscles around joint -help support joint & limit range of motion v. bursae: pockets of synovial fluid -cushion areas where tendons or ligaments rub d) injuries of synovial joints i. dislocation (luxation) -articular surfaces forced out of position ii. subluxation = partial dislocation  iii. double-jointed = weaker stability at joint -more prone to dislocation -greater range of motion 6) understanding the trade off Range of motion ----------------------------------------------------------------> Synarthrosis amphiarthrosis diarthrosis