joints

joint

articulation or junction between two or more bones or cartilage

classifications of joints

structure and function

structural classification of joints

fibrous, cartilaginous, synovial

functional classification of joints

synarthrotic, amphiarthrotic, diarthrotic

fibrous joints

dense connective tissues connect bones

between bones in close contact

cartilaginous joints

hyaline cartilage or fibrocartilage connect bones

synovial joints

most complex

joint capsule

synovial fluid

reinforcing ligaments and cartilage

all of these joints are also diarthrotic joints that allow free mobility

synarthrotic joints

immovable joints

amphiarthrotic joints

slightly movable joints

diarthrotic joints

joints with free mobility

always synovial joints

Bony Joints may form when..

fibrous or cartilaginous joints ossify

Fibrous synarthotic joints

immovable; no movement is permitted between bones; all are composed of a dense fiborous connective tissue holding bones together

sutures of the skull and gomphosis

suture

seams between adjacent bones (bones of the skull)

connected by dense connective tissue

connected periosteum (connected over whole skull)

fibrous synarthotic joint

Gomphosis

tooth in sockets of mandible and maxilla using periodontal ligament

fibrous synarthotic joint

synchondrosis

cartilaginous synarthotic joint

bands of hyaline cartilage unite bone

growth plate (temporary) -- while growing

between the manubrium and the first rib (costal cartilage)

syndesmosis joint

bones connected by a ligament

ex. membrane between tibia and fibula

fibrous amphiarthotic joint

symphysis

pass of fibrocartilage unite bones

ex. intervertebral discs or pubic symphysis

cartilaginous amphiarthotic joint

General Structure of Synovial Joints

Have following basic features

articular cartilage of synovial joint

only on articulating surface

similar to hyaline cartilage

watery matrix

joint capsule of synovial joint

fibrous outer layer and synovial membrane

connective tissue that encloses the cavity and retains the fluid; connect periosteum

fibrous outer layer of joint capsule

dense connective tissue

synovial membrane of joint capsule

inner surface, areolar tissue and incomplete epithelium

secrete synovial fluid

synovial fluid of synovial joint

within joint cavity

viscous (similar to interstitial fluid with proteoglycans)

secreted by cells of the synovial membrane

lubricant, shock absorber, nutrient distrubutor

accessory structures of synovial joints

meniscus, fat pads, bursa

Meniscus

fibrocartilage additional layer between articulating bones

subdivide cavity, channel fluid, alter shape of articulating surface

accessory structure of synovial joint

fat pads

adipose covered by synovial membrane

protect articular cartilage

packing material

shock absorber

accessory structure of synovial joint

bursa

pockets of synovial fluid surrounded by membrane

reduce friction at site of tendon and ligament attachment

accessory structure of synovial joint

Ligaments attach _____ to _____

bone to bone

Tendons attach _____ to _____

muscle to bone

ligaments and tendons

Attach via fibrocartilage transition to periosteum

Dense regular connective tissue

thick parallel bundles of collagen

differences between ligaments and tendons

ligaments are more flat, tendons are more round

ligaments are slightly less dense

Proprioceptors

monitor the position and movement of skeletal muscles and joints
- providing info about body position to brain

muscle spindles, golgi organs, joint capsule receptors

muscle spindles

specialized muscle fibers throughout a muscle (neighbor regular muscle fibers)

sarcomeres on either end of a region devoid of filaments (wrapped by sensory neurons)

respond when stretched
- sending signal to CNS saying that happened

Golgi tendon organs

sensory dendrites interwoven among collagen fibers of tendons

when tendon tightens, signals the sensory neurons

info about degree of contraction in a muscle

joint capsule receptors

variety of receptors found on sensory dendrites in joint capsule

responds to pressure and stretch/movement

ex. pacinian corpuscles and Ruffini endings -- mechanoreceptors

accessory structures of the elbow

-many reinforcing ligaments and accessory structures
-annular ligament
-Olecranon Bursa

annular ligament

binds the head of the radius to the ulna

nursemaid's elbow

Nursemaid's elbow

partial dislocation (subluxation) of radial head

olecranon bursa

on posterior side of the elbow
eases the movement of the tendons over the joint

student's elbow

accessory structures of the knee

Medial and lateral menisci
Fat pads
ACL and PCl
MCL and LCL

medial and lateral menisci of knee

fibrocartilage pads between femur and tibia

anterior cruciate ligament (ACL) and posterior cruciate ligament (PCL)

femur to tibia

limit anterior/posterior movements

medial collateral ligament (MCL) and lateral collateral ligament (LCL)

femur + tibia

stabilize the knee in standing position

unhappy triad knee injury

damage to medial collateral ligament (MCL), lateral meniscus, and anterior cruciate ligament (ACL)

cause of unhappy triad

caused by strong force to the outside of the knee when foot is stationary (e.g. during a tackle)

treatment of unhappy triad

ACL tear commonly requires a graft (tendon graft)

MCL and meniscus require immobilization

arthritis

inflammation of a joint

Osteoarthritis

most common type of arthritis

~ 85% of Americans over 70

gradual deterioration of articular cartilage with advancing age

bone rubs against bone at joint

rheumatoid arthritis

second most common type of arthritis

chronic inflammation of synovial membranes

primary affects joints in hands and feet

autoimmune disorder