Anatomy and Physiology- Chapter 9: Joints

fibrous joints

bones held together by dense collagen fibers; mostly synarthrotic- ex: your skull bones are held together by fibrous joints

lack cartilage and a synovial cavity

heald closely together by dense irregular connective tissue; suture joints and teeth joints

cartilaginous joints

bones held together by cartilage- ex: pubic symphisis and between the spine; most are amphiarthrotic

lack synovial cavity

synovial joints

bones held together by ligaments; mostly diarthrotic- ex: arm joint

ligaments hold bones together to form synovial cavity

two layered capsule encloses synovial cavity- outer fibrous capsul and inner synovial membrane

surrounded by accessory structures: joint capsule, ligaments, sometimes bursae

synarthrosis

an immovable joint; mostly fibrous joints- ex: skull bones

amphiarthrosis

slightly moveable joint- ex: pubic symphisis; mostly cartilaginous joints

diarthrosis

a freely moving joint- ex: all f your appendages (arms, legs, etc); all synovial joints

synovial fluid

secreted by the synovial membrane in the capsule; functions to reduce friction by lubricating the joint and absorbing shock; supplies oxygen and nutrients to the cartilage

joint capsule

composed of dense irregular connective tissue and lined by a synovial membrane; encompass the joint cavity and synovial fluid within it; consistent with periosteum

ligaments

bands of dense regular CT (like tendons) that join one bone to another bone

bursae

(and tendon sheaths) fluid-filled structures strategically placed to minimize friction in some joints

menisci

pads of dense fibrocartilage found between the articular surfaces in some joints; provide superior strength and allow bones of different shapes to fit together tighter

arterial branches

several different arteries merge around a joint before penetrating the articular capsule

nerve endings

respond to the degree of movement and stretch, and convey info about pain from the joint to the spinal cord and brain

6 types of synovial joints

plane, hinge, pivot, condyloid, saddle, ball and socket

planar joint

articulating surface is flat or slightly curved, permitting back and forth and side-to-side movements- ex: the tarsals

hinge joint

the convex surface of one bone fits into the concave surface of another, producing an opening and closing action like a hinge

pivot joint

the rounded surface of one bone articulates with a ring structure formed by another bone and a ligament (allowing rotation around its longitudinal axis)- ex: turning your hand, shaking your head

condyloid joint

convex oval-shaped projection of one bone fits into the oval-shaped depression of another bone (allowing movement around two axes)- ex: wrist

saddle joint

articular surface of one bone is saddle-shaped; this is really a modified condyloid joint, but the range of motion is expanded to include movement around all 3 axes- ex: thumb

ball-and-socket joint

ball surface of one bone fits into a cuplike depression of another bone; allows the most movement of any joint- ex: shoulder joint

factors that affect ROM

1) structure or shape of the articulating bones - shape of articulating bones determines how closely they fit together

2) the strength and tension of muscles and joint ligaments - varies to restrict or permit certain positions

3) hormones - relaxin increases the flexibility of the pubic symphisis during pregnancy

4) disuse - movement may be restricted if a joint has not been used for an extended period

gliding

relatively flat bone surfaces move back-and-forth and from side-to-side with respect to one another - ex: waving

limited in range .. typically intercarpal joints

angular movements

there is an increase or decrease in the angle between articulating bones - ex: the elbow ... flexion, extension, abduction, adduction

rotation

a bone revolves around its own longitudinal axis - ex: shaking your head no

flexion

angular movement - decrease in the angle

extension

angular movement - increase in the angle

abduction

angular movement - movement away from the midline - ex: beginning of a jumping jack

adduction

angular movement - movement toward the midline - ex: 2nd half of a jumping jack

circumduction

angular movement - movement of a body part in a circle - ex: doing "arm circles" in gym class or playing Skip-It

elevation

special movement - upward movement of a body part - ex: closing the mouth

depression

special movement - downward movement of a body part - ex: opening the mouth

protraction

special movement - movement of a body part anteriorly (retraction is the reverse)

inversion

special movement - movement of the foot medially - ex: move the soles of the feet together (like in yoga)

eversion

special movement - moving the foot laterally

dorsiflexion

special movement - bending the foot at the ankle in an upward direction - ex: walking on your heels

plantar flexion

bending the foot at the ankle in a downward direction - ex: dancing on your toes like a ballerina or pressing the gas pedal

supination

special movement - movement of the forearm so that the palm is turned upward

pronation

special movement - movement of the forearm so that the palm is turned downward

opposition

special movement - movement of our opposable thumb across the palm to touch the tips of the fingers on the same hand

temporomandibular joint

combined hinge and planar joint formed by the mandible and the temporal bone

osteoarthritis

thinning of the articular cartilage and decreased production of synovial fluid in joints- ligaments shorten and lose elasticity