lecture 1c: joints

classifications

structural or functional

structural classification of joints

• how they’re linked

• fibrous

• cartilaginous

• synovial

functional classification of joints

• how the move

• synarthrotic

• amphiarthrotic

• diarthrotic

syarthrotic

immovable

amphiarthrotic

slightly moveable

diarthrotic

freely movable

joint

point of attachment between two bones

fibrous joints

• held together with dense CT containing many collagen fibers

• found in bones close in contact

• 3 types

  • syndesmosis

  • suture

  • gomphosis

syndesmosis

• bones bound by a sheet of dense CT (interosseous membrane) or a bundle of dense (regular) connective tissue (interosseous ligament)

• amphiarthrotic (flexible, may twist)

• ex.: b/w tibia and fibula

suture

fibrous

• between flat bones of skull

• thin layer of connective tissue sutural ligament) connects bones

• synarthrotic (immovable)

• chiropractors can put pressure on but can’t move

gomphosis

fibrous

• cone-shaped bony process in a socket in jawbone

• tooth in jawbone, anchored by periodontal ligament

• synarthrotic (immovable)

cartilagenous joints

• 2 types

• connected by hyaline cartilage or fibrocartilage

  • synchondrosis

  • symphysis

synchondrosis

cartilaginous

• bands if HYALINE cartilage unite bones

• some are temporary, such as epiphyseal plate (ossification converts this to a synostosis)

• between manubrium and first rib (costal cartilages, permanent, synarthrotic)

  • if it was all bone, CPR wouldn’t work

symphysis

cartilagenous

• pad of FIBROUS cartilage between bones

  • toughest cartilage - absorbs shock when walking/running

• amphiarthrotic

• pubic symphysis & intervertebral discs

synovial joints

• most joints

• diarthrotic

• movable

structure of synovial joint

• articular cartilage covers articular end of bones

  • made of HYALINE cartilage (all bones start as hyaline, moves to end as ossified)

• joint capsule, consists of 2 laters

  • outer fibrous layer, composed of ligaments

  • inner layer, synovial membrane, which secretes synovial fluid

bursa

• reduce friction between structures

synovial membrane

• makes/secretes synovial fluid

types of synovial joints

6:

• ball-and-socket

• condylar

• plane

• hinge

• pivot

• saddle

ball and socket

• round head in cup-shaped cavity

• widest range of motion

• multiaxial, plus rotation

• hip, shoulder

condylar joint (aka ellipsoidal)

• oval condyle fits into elliptical cavity

• back-and-forth, side to side (biaxial, no rotation)

• between metacarpals and phalanges

plane (gliding) joint

• almost flat, or slightly curved

• back-and-forth and twisting

• nonaxial movement

• wrist and ankle joints

hinge joint

• convex surface fits into concave surface of other bone

• uniaxial

• elbow, between phalanges, mandible

pivot joint (trochoid)

• cylindrical surface rotates within ring of other bone

• uniaxial (rotation only)

• atlas (C1) and dens of axis (C2)

saddle joint (sellar)

• both bones have concave and convex surfaces

• biaxial movement

• carpal and metacarpal of thumb

origin

• relatively fixed end of the muscle (aka proximal)

  • doesn’t move

insertion

• more moveable end of skeletarl muscle (aka proximal)

movement at a joint occurs when a muscle__ and its fibers pull the __ towards the __

• contract, insertion, origin

dorsiflexion vs plantar flexion

• dorsiflexion: toes up toward you

• plantarflexion: planting something in ground

circumduction vs rotation

• circumduction is flexion + extension and ab+adduction combination, making a circle

• rotation is spinning a bone around its long axis

supine vs prone

• supine = face up

• prone = face down

inversion vs eversion

• inversion: turn sole of foot in medially

• eversion: turn sole foot laterally