exam 3

synovial joint (diarthrosis)

\-joint in which 2 bones are separated by a joint cavity

\-most are freely mobile

\-most structurally complex type of joint

\-most likely to develop painful dysfunction

articular cartilage

\-layer of hyaline cartilage that covers the facing surfaces of 2 bones

\-usually 2 or 3 mm thick

joint (articular) cavity

separates articular surfaces

synovial fluid

\-slippery lubricant in joint cavity

\-rich in albumin and hyaluronic acid, gives it a viscous slippery texture like rae egg whites

\-nourishes articular cartilage and removes waste

\-makes movement of synovial joints almost friction free

joint (articular) capsule

\-connective tissue that encloses the cavity and retains the fluid

\-outer fibrous capsule, continuous with periosteum of adjoining bones (collagen fibers)

\-inner, cellular, synovial membrane; composed mainly of fibroblast-like cells that secrete synovial fluid and macrophages that remove debris from the joint cavity

articular disc

forms a pad between articulating bones that crosses the entire joint capsule

meniscus

\-moon shaped cartilage in knee; extend inward from the left and right

\-absorb shock and pressure

\-guide bones across each other and improve their fit together

\-stabilize the joints, reducing the chance of dislocation

bursa

\-fibrous sac filled with synovial fluid, located between muscles, where tendons pass over bone, or between bone and skin

\-cushions muscles, helps tendons silde more easily over joints, modifies direction of tendon pull

tendon sheath

\-elongated cylindrical bursa wrapped around tendon

\-in hand and foot

tendon

strip of collagenous tissue attaching muscle to bone

ligament

strip of collagenous tissue attaching one bone to another

exercise and articular cartilage

\-Exercise warms synovial fluid, becomes less viscous, more easily absorbed by cartilage

\-Cartilage then swells and provides a more effective cushion

\-Warm-up period before vigorous exercise helps protect cartilage from undue wear and tear

\-Repetitive compression of nonvascular cartilage during exercise squeezes fluid and metabolic waste out of the cartilage

\-When weight removed, cartilage absorbs synovial fluid like a sponge taking in oxygen and nutrients to the chondrocytes

\-Without exercise, cartilage deteriorates more rapidly from inadequate nutrition and waste removal

lever

\-any elongated, rigid object that rotates around a fixed point called a fulcrum

\-rotation occurs when an effort applied overcomes resistance (load) at some other point

\-resistance arm and effort arm are described relative to fulcrum

range of motion (ROM)

\-the degrees through which a joint can move

\-determined by:

\-structure of the articular surfaces

\-strength and tautness of ligaments and joint capsules

\-action of the muscles and tendons

axis of rotation

relatively stationary point that passes through the bone in a direction perpendicular to the plane of movement

multiaxial joint

shoulder joint has 3 degrees of freedom or axes of rotation

ball and socket joint

\-smooth, hemispherical head fits within cup-like socket

\-only multiaxial joints in body

\-ex: shoulder and hip

condylar (ellipsoid) joints

\-oval convex surface of one bone fits into a complementary-shaped depression on the other

\-ex: radiocarpal joint and metacarpophalangeal joints

saddle joint

\-both bones have an articular surface that is shaped like a saddle, one concave, the other convex

\-biaxial joints

\-ex: trapeziometacarpal (opposable thumb) and sternoclavicular joint

plane (gliding) joint

\-flat articular surfaces, bones slide over each other

\-usually biaxial joints

\-ex: between carpal bones of wrist, between tarsal bones of ankle, also between articular processes of vertebrae

hinge joint

\-one bone with convex surface fits into a concave depression of another bone

\-monoaxial joint

\-ex: elbow, knee, joints within fingers, toes

pivot joint

\-a bone spins on its longitudinal axis

\-monoaxial joints

\-ex: atlantoaxial joint (C1 and C2) and radioulnar joint at the elbow

zero position

the position of a joint when a person is in the standard anatomical position

flexion

\-movement that decreases joint angle

\-common in hinge joints

extension

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

hyperextenion

extension of a joint beyond the zero position

abduction

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

adduction

movement in the frontal plane back toward the midline

elevation

movement that raises a body part vertically in the frontal plane

depression

movement that lowers a body part in the same plane

protraction

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

retraction

posterior movement

circumduction

one end of an appendage remains stationary while other end makes a circular motion

rotation

\-movement in which a bone spins on its longitudinal axis

\-medial=inward

\-lateral=outward

pronation

forearm movement that turns palm to face either posteriorly or downward

supination

forearm movement that turns palm to face anteriorly or upward

lateral flexion

tilting the head or trunk to the right or left at the midline

lateral excursion

right or left movement from zero position

medial excursion

\-movement back to the median, zero position

\-side to side grinding during chewing

radial flexion

tilting hand toward thumb

ulnar flexion

tilting hand toward little finger

palmar abduction

moving thumb away from hand and pointing it anteriorly

radial abduction

moving thumb away from index finger (90°)

flexion of thumb

tip of thumb directed toward palm

extension of thumb

straightening the thumb

opposition

moving thumb to touch tip of a finger

reposition

returning thumb to the zero position

dorsiflexion

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

plantar flexion

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

inversion

movement in which the soles are turned medially

eversion

movement in which the soles are turned laterally

supination of foot

complex combination of plantar flexion, inversion, and adduction

pronation of foot

complex combination of dorsiflexion, eversion, and abduction

joint diseases

\-synovial fluid less abundant and articular cartilage thinner or absent producing friction that causes pain

\-breathing difficult due to calcification of sternocostal joints

\-degeneration of intervertebral discs causing back pain and stiffness

muscle functions

movement, stability, control of openings, heat production, and glycemic control

movement

\-Move from place to place; move body parts; move body contents in breathing, circulation, and digestion

\-In communication: speech, writing, facial expressions and other nonverbal communications

stability

\-Maintain posture by preventing unwanted movements

\-Antigravity muscles: prevent us from falling over

\-Stabilize joints by maintaining tension

sphincters

internal muscular rings that control the movement of food, blood, and other materials within body

glycemic control

Muscles absorb and store glucose which helps regulate blood sugar concentration within normal range

myology

the study of the muscular system

epimysium

\-Fibrous sheath surrounding entire muscle

\-Outer surface grades into fascia; inner surface projections form perimysium

fascia

Sheet of connective tissue that separates neighboring muscles or muscle groups from each other and the subcutaneous tissue

endomysium

\-Thin sleeve of loose connective tissue around each fiber

\-Allows room for capillaries and nerve fibers

\-Provides chemical environment for muscle fiber

perimysium

\-thicker layer of connective tissue that wraps fascicles

\-carries nerves, blood vessels, and stretch receptors

fusiform

thick in the middle and tapered at each end

parallel

uniform width and parallel fascicles

triangular (convergent)

broad at one end and narrow at the other

pennate

feather shaped

unipennate

fascicles approach tendon from one side

bipennate

fascicles approach tendon from both sides

multipennate

bunches of feathers converge to a single point

circular (sphincters)

form rings around body openings

muscle compartment

\-a group of functionally related muscles enclosed by fasica

\-also contains nerves and blood vessels that supply the muscle group

intermuscular septa

very thick fascia that separate one compartment from another

aponeurosis

tendon is a broad, flat sheet

retinaculum

connective tissue band that tendons from separate muscles pass under

direct (fleshy) attachment

\-little separation between muscle and bone

\-muscle seems to emerge directly from bone

intrinsic

entirely contained within a region, such as the hand

extrinsic muscle

acts on a designated region, but has one attachment elsewhere

prime mover (agonist)

muscle that produces most of force during a particular joint action

synergist

\-muscle that aids the prime mover

\-may contribute additional force, modify the direction of movement, or stabilize a nearby joint

antagoinst

\-opposes the prime mover

\-prevents excessive movement

\-sometimes relaxes to give prime mover control over and action

antagonistic pairs

muscles that act on opposite sides of a joint

fixator

muscle that prevents movement of bone

innervation

\-refers to the identity of the nerve that stimulates it

\-enables diagnosis of nerve, spinal cord, and brainstem injuries from muscle tests

spinal nerves

\-arise from the spinal cord

\-emerge through intervertebral foramina

\-immediately branch into posterior and anterior rami

\-innervate muscles below the neck

plexus

web-like network of spinal nerves adjacent to the vertebral column

cranial nerves

\-arise from the base of the brain

\-emerge through skull foramina

\-innervate the muscles of the head and neck

\-numbered CN I to CN XII

how muscles are named

\-latin names

\-describes distinctive aspects of the structure, location, or action of a muscle

excitability (responsiveness)

\-to chemical signals, stretch, and electrical changes across the plasma membrane

\-respond to environmental changes called stimuli

conductivity

\-local electrical excitation sets off a wave of excitation that travels around the muscle fiber

\-Respond to stimuli by producing electrical signals that are quickly conducted to other cells at distant locations

contractility

shortens when stimulated

extensibilty

capable of being stretched between contractions

elasticity

returns to its original rest length after being stretched

sarcolemma

plasma membrane of a muscle fiber

sarcoplasm

cytoplasm of a muscle fiber

myofibrils

long protein cords occupying most of sarcoplasm

glycogen

carbohydrate stored to provide energy for exercise

myoglobin

red pigment; provides some oxygen needed for muscle activity