Ch. 8 Articulations Lecture PP

Bones and Cartilages of the Human Body

Joint (articulation) classifications

A. definition:

site at which 2 or more bones meet

joint (articulation) classifications

B. classification by movement:

S = Synarthrosis (none)

A = Amphiarthrosis (little)

D = Diarthrosis (freely)

joint (articulation) classifications

C. classification by structure:

1. fibrous

2. cartilagenous

3. synovial

fibrous structural joints: sutures image

fibrous structural joints image

cartilaginous joints image

synovial joints: general structure image

structure and function of synovial joints

articular cartilage:

covers ends of bones, specialized hyaline (incr. water content)

structure and function of synovial joints

joint cavity:

potential space

structure and function of synovial joints

articular capsule:

fibrous joint covering, inner lining is a synovial membrane

structure and function of synovial joints

synovial fluid:

present in cavity to assist lubrication, will be pumped in/out of matrix, across synovial membrane

structure and function of synovial joints

reinforcing ligaments:

a. intrinsic: thickening of the joint capsule

b. extracapsular: outside capsule

c. intracapsular: inside capsule

synovial joints: knee - other supporting structures

structure and function of synovial joints

meniscus:

articular disc, exists as a fibrocartilage pad between

structure and function of synovial joints

bursae:

small pockets of synovial fluid at the interface of ligaments and tendons with surrounding tissue

structure and function of synovial joints

tendon sheath:

elongated bursa, wraps around the tendon

synovial joints: friction-reducing structures image

structure and function of synovial joints

c. joint stabilization -

1. reinforcing ligaments

2. shapes of bones at articular surfaces

3. muscle tone

NOTE: bone may still move out of alignment= dislocation (luxation)

*when articular surfaces forced out of position

*”subluxation”= partial dislocation

*”double-jointed”= joints are weekly stabilized

monaxial joints:

a. hinge (knee and elbow)

b. pivot (between atlas & axis, radius & ulna)

biaxial:

a. gliding (plane): wrist and vertebrae (flat surfaces)

b. coldyloid: metacarpals and phalanges (knuckles)

c. saddle: at base of thumb (metacarpal with carpal)

triaxial:

all ball and socket joints (shoulder, hip)