Bio214 Exam 3

Joint functions

\-link the bones of the skeletal system

\-permit effective movement

\-protect the softer organs

What does joint anatomy and movements do for the study of muscle actions?

provide a formation

Synovial joint (diarthrosis)

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

\-most are freely mobile

\-most are structurally complex type of joint

\-most likely to develop painful dysfunction

Articular cartilage

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

\-joint articular cavity

\-synovial fluid

\-joint articular capsule

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 raw 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

\-inner, cellular, synovial membrane

Outer fibrous capsule

continuous with periosteum of adjoining bones

Inner, cellular, synovial membrane

composed mainly of fibroblast-like cells that secrete synovial fluid and macrophages that remove debris from the joint cavity

In a few synovial joints, fibrocartilage grows ___ from the joint capsule

\-inward

\-e.g, temporomandibular joint, menisci

Meniscus

\-moon-shaped cartilage in knee; in each knee, menisci extend inward from left to right

\-absorb shock and pressure

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

\-stabilize the joints, reducing the chance of dislocation

Accessory structures of synovial joints

\-Bursa

\-Tendon sheath

\-Tendon

\-Ligament

Bursa

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

Bursa functions

\-cushions muscles

\-helps tendons slide more easily over joints

\-modifies direction of tendon pull

Tendon sheath

\-elongated cylindrical bursa wrapped around a tendon

\-in hand and foot

Tendon

strip of collagenous tissue attaching muscle to bone

Ligament

strip of collagenous tissue attaching one bone to another

What does exercise do to synovial fluid?

\-warms the fluid

\-makes it become less viscous

\-makes it more easily absorbed by cartilage

\-cartilage then swells and provides a more effective cushion

What helps protect cartilage from undue wear and tear?

warming up before vigorous exercise

What does repetitive compression of nonvascular cartilage during exercise do?

squeezes fluid and metabolic waste out of the cartilage

What happens the weight removal period during exercise?

cartilage absorbs synovial fluid like a sponge taking in oxygen and nutrients to the chondrocytes

What happens without exercise?

cartilage deteriorates more rapidly from inadequate nutrition and waste removal

Long bones act as ___

levers to enhance the speed or power of limb movements

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

What is ROM determined by?

\-structure of the articular forces (biggest factor)

\-strength and tautness of ligaments and joint capsules

\-action of the muscles and tendons

Muscle tone

state of tension maintained in resting muscles

Axis of rotation

a moving bone has a relatively stationary axis of rotation 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

Monoaxial

having a single axis

Biaxial

having two axes

What are the 6 classes of synovial joints?

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

Ball-and-socket joints

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

\-only multiaxial joints in body

\-e.g., hip, shoulder

Condylar (ellipsoid) joints

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

\-biaxial joints: movement in two planes

\-e.g., radiocarpal joint, metacarpophalangeal joints

Saddle joints

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

\-biaxial joints

\-e.g., trapeziometacarpal (opposable thumb), sternoclavicular joint

Plane (gliding) joints

\-flat articular surfaces, bones slide over each other

\-usually biaxial joints

\-e.g., between carpal bones of wrist; between tarsal bones of ankle; also between articular processes of vertebrae

Hinge joints

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

\-monoaxial joints: move freely in one plane

\-e.g., elbow, knee, joints within fingers, toes

Pivot joints

\-a bone spins on its longitudinal axis

\-monoaxial joints

\-e.g., atlantoaxial joint (C1 and C2), radioulnar joint at the elbow

Zero position

the position of a joint when a person is in 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

Hyperextension

\-extension of a joint beyond the zero position

\-flexion and extension occur at nearly all diarthroses, hyperextension is limited to a few\`

Abduction

\-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

Adduction

movement in the frontal plane back toward midline

Hyperadduction

crossing fingers, crossing ankles

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 appendage remains stationary while other end makes a circular motion

\-e.g., artist painting a circle on a canvas

Rotation body movement

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

\-rotation of trunk, thigh, head, or arm

Medial (internal) rotation

turns bone inward

Lateral (external) rotation

turns bone outward

Pronation

\-forearm movement that turns palm to face either posteriorly or downward

\-head of radius spins

\-radius crosses stationary ulna like an X

Supination

\-forearm movement that turns palm to face anteriorly or upward

\-forearm supinated in anatomical position

\-radius is parallel to ulna

Flexion of the trunk

forward-bending movements at the waist or neck

Extension of the trunk

straightens trunk or neck

Hyperextension of the trunk

bending over backwards

Lateral flexion of the trunk

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

Lateral excursion of the mandible

right or left movement from the zero position

Medical excursion of the mandible

movement back to the median, zero position

\-side-to-side grinding while chewing

Radial flexion

tilting hand towards thumb

Ulnar flexion

tilting hand towards pinky

Abduction and adduction of digits

spreading your fingers apart and bringing them back together

Flexion and extension of digits

curling and straightening your fingers

Palmar abduction

moving thumb away from hand and pointing it anteriorly

Radial abduction

moving thumb away from index finger (90 degrees)

Flexion of thumb

tip of thumb directed towards palm

Extension of thumb

straightening the thumb

Opposition

moving thumb to touch tip of a finger

Reposition

returning thumb to 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 tip-toe (toe-off)

Inversion

movement in while the soles are turned medially

Eversion

movement in which the soles ar turned laterally

Supination of foot

complex combination of plantar flexion, inversion, and adduction

Pronation of foot

complex combination of dorsiflexion, eversion, and abduction

What happens to the joints with joint disease?

it becomes less abundant and articular cartilage becomes thinner or absent producing friction that causes pain

What is a common joint disability?

osteoarthritis

What happens due to calcification of sternocostal joints?

breathing becomes difficult

What causes back pain and stiffness?

deterioration of intervertebral discs

Muscle functions

\-movement

\-stability

\-control of openings

\-heat production

\-glycemic control

Function of movement in muscles

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

\-speech, writing, facial expressions, and other nonverbal communications

Function of stability in muscles

\-maintain posture by preventing unwanted movements

\-antigravity muscles: prevent us from falling over

\-stabilize joints by maintaining tension

Function of control of openings and passageways in muscles

sphincters

Sphincters

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

Function of heat production in muscles

our skeletal muscles provide as much as 85% of our body heat

Function of glycemic control in muscles

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

How many muscles are in the human body?

about 600

Skeletal muscles constitute about ___ of our body weight

half

What are the three kinds of muscle tissues?

\-skeletal

\-smooth

\-cardiac

What is the one main purpose skeletal muscles specialized for?

converting the chemical energy in ATP into the mechanical energy of motion

Myology

the study of the muscular system

Mys- prefix

muscle

Epimysium

\-fibrous sheath surrounding entire muscle

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

What is the most superficical part of the muscle?

epimysium

Epimysium function

hold the muscle together

Fascia

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