anatomy chapter 9 joints

cartilaginous, fibrous, bony, synovial

• synostosis; joint formed when the gap between two bones ossify, and they become in effect, a single bone
• frontal and mandibular bones in infants
• cranial sutures in elderly
• attachment of first rib and sternum with old age

can occur in either fibrous or cartilaginous joint

• synarthrosis, or synarthrodialjoint –a point at which adjacent bones are bound by collagen fibers that emerge from one bone, cross the space between them, and penetrate into the other
• Three kinds of fibrous joints–sutures–gomphoses–syndesmoses

• Sutures-immovable or slightly movable fibrous joints that closely bind the bones of the skull to each other
• •Sutures can be classified as:
• –serrate–interlocking wavy lines •coronal, sagittal and lambdoid sutures
• –lap(squamous)-overlapping beveled edges •temporal and parietal bones
• –plane(butt)-straight, nonoverlappingedges•palatine processes of the maxillae

• kind of fibrous joint
• Gomphosis-attachment of a tooth to its socket
• •Held in place by fibrous periodontal ligament–collagen fibers attach tooth to jawbone–allows the tooth to move a little under the stress of chewing

• kind of fibrous joint
• syndesmosis–longer collagenous fibers than in a suture or gomphosis
• –More mobility–interosseusmembrane

• •Most mobile syndesmosis–interosseusmembranes unite radius to ulna allowing supinationand pronation
• •Least mobile syndesmosis–tibia to fibula

• amphiarthrosis or amphiarthrodialjoint–two bones are linked by cartilage
• •Two types of cartilaginous joints–synchondroses–symphyses

• Synchrondrosis-bones are bound by hyaline cartilage
• –temporary joint in the epiphysealplate in children
• •binds epiphysis and diaphysis
• –first rib attachment to sternum
• •other costal cartilages are joined to sternum by synovial joints

• Symphysis-two bones joined by fibrocartilage
• –pubic symphysis in which right and left pubic bones joined by interpubicdisc
• –bodies of vertebrae and intervertebraldiscs•only slight amount of movement between adjacent vertebrae•collective effect of all 23 discs gives spine considerable flexibilityPubic

• diarthrosis or diarthrodial joint
• –joint in which two bones are separated by a space called a joint cavity
• •Most familiar type of joint; Most are freely movable; Most structurally complex type of joint; Most likely to develop painful dysfunction; Most important joints for physical and occupational therapists, athletic coaches, nurses, and fitness trainers

layer of hyaline cartilage that covers the facing surfaces of two bones–usually 2 or 3 mm thick

• –slippery lubricant in joint cavity
• –rich in albumin and hyaluronicacid
• –gives it a viscous, slippery texture like raw egg whites
• –nourishes articularcartilage and removes waste
• –makes movement of synovial joints almost friction free

• –connective tissue that encloses the cavity and retains the fluid–outer fibrous capsule
• –continuous with periosteumof adjoining bones
• –inner, cellular, synovial membrane-composed mainly of fibroblast-like cells that secrete synovial fluid and macrophagesthat remove debris from the joint cavity

In a few synovial joints,fibrocartilagegrows inward from the joint capsule

• forms a pad between articulating bones that crosses the entire joint capsule
• •temporomandibular joint, distal radioulnar joints, sternoclavicular and acromioclavicular joints

• in the knee, two cartilages extend inward from the left and right but do not entirely cross the joint
• •these cartilages absorb shock and pressure•guide bones across each other
• •improve the fit between bones•stabilize the joints, reducing the chance of dislocation

• a strip or sheet of tough collagenousconnective tissue that attaches muscle to bone
• •the most important structures in stabilizing a joint

similar tissue that attaches one bone to another

• a fibrous sac filled with synovial fluid, located between adjacent muscles, where tendon passes over bone, or between bone and skin
• •cushion muscles, helps tendons slide more easily over joints, modify direction of tendon pull

• elongated cylindrical bursae wrapped around a tendon
• •in hand and foot

calculated from the length of the effort arm divided by the length of the resistance arm•MA > 1.0 –the lever produces more force, but less speed and distance, than the force exerted on it•MA < 1.0 –the lever produces more speed or distance, but less force, than the input

• Has fulcrum in the middle between effort and resistance (RFE)
• •Atlanto-occipital joint lies between the muscles on the back of the neck and the weight of the face
• –loss of muscle tone occurs when you nod off in class

• Resistance between fulcrum and effort (FRE)
• •Resistance from the muscle tone of the temporalismuscle lies between the jaw joint and the pull of the digastricmuscle on the chin as it opens the mouth quicklyE

• Effort between the resistance and the fulcrum (REF)
• –most joints of the body
• •The effort applied by the biceps muscle is applied to the forearm between the elbow joint and the weight of the hand and the forearm

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

• Smooth, hemispherical head fits within a cuplike socket
• –shoulder joint -head of humerus into glenoid cavity of scapula
• –hip joint -head of femur into acetabulumof hip bone
• •The only multiaxialjoints in the body

• (ellipsoid joints)
• Oval convex surface on one bone fits into a complementary shaped depression on the other
• – radiocarpal joint of the wrist
• –metacarpophalangeal joints at the bases of the fingers
• •Biaxial joints –movement in two planes

• Both bones have an articular surface that is shaped like a saddle, concave in one direction and convex in the other
• –trapeziometacarpal joint at the base of the thumb
• –sternoclavicularjoint –clavicle articulates with sternum
• •Biaxial joint–more movable than a condyloidor hinge joint forming the primate opposable thumb

• (gliding joints)
• Flat articular surfaces in which bones slide over each other with relatively limited movement
• •Usually biaxial joint–carpal bones of wrist–tarsal bones of ankle–articular processes of vertebrae
• •Although any one joint moves only slightly, the combined action of the many joints in wrist, ankle, and vertebral column allows for considerable movement

• One bone with convex surface that fits into a concave depression on other bone
• –elbow joint -ulna and humerus
• –knee joint -femur and tibia
• –finger and toe joints
• •Monoaxialjoint –move freely in one plane

• One bone has a projection that is held in place by a ring-like ligament
• •Bone spins on its longitudinal axis–atlantoaxialjoint (dens of axis and atlas)
• •transverse ligament–proximal radioulnarjoint allows the radius to rotate during pronationand supination
• •anular ligament
• •Monoaxial joint

• movement that decreases the a joint angle
• –common in hinge joints

movement that straightens a joint and generally returns a body part to the zero position

further extension of a joint beyond the zero position–flexion and extension occur at nearly all diarthroses, hyperextension is limited to a few

movement of a body part in the frontal plane away from the midline of the body

–hyperabduction–raise arm over back or front of head

movement in the frontal plane back toward the midline

–hyperadduction–crossing fingers, crossing ankles

a movement that raises a body part vertically in the frontal plane

lowers a body part in the same plane

the anterior movement of a body part in the transverse (horizontal) plane

posterior movement

• one end of an appendage remains stationary while the other end makes a circular motion
• •Sequence of flexion, abduction, extension and adduction movements
• –baseball player winding up for a pitch

movement in which a bone spins on its longitudinal axis–rotation of trunk, thigh, head or arm

turns the bone inwards

turns the bone outwards

right or left movement from the zero position

movement back to the median, zero position–side-to-side grinding during chewing

tilt hand towards little finger

tilts hand toward the thumb

curling fingers

straightening them

spread them apart

bring fingers back together

tip of thumb directed toward palm

straightening the thumb

move thumb away from index finger 90°

moves thumb away from hand and points it anteriorly

moves it to the zero position

move the thumb to touch the tips of any of the fingers

return the thumb to the zero position

elevation of the toes as you do while swinging the foot forward to take a step (heel strike)

extension of the foot so that the toes point downward as in standing on tiptoe (toe-off)

a movement in which the soles are turned medially

a movement in which the soles are turned laterally

complex combination of plantar flexion, inversion, and adduction

complex combination of dorsiflexion, eversion, and abduction

• pages 14-21 of notes
• TMJ, shoulder, hip, elbow, knee, ankle, arthritis, prosthetics