Unit 1 I Flashcards
Portion of the skeleton that forms the central axis of the body; skull, vertebral column, and bony thorax
Axial skeleton
Bones of the limbs and limb girdles that are attached to the axial skeleton
Appendicular skeleton
Vertical plane that divides the body into anterior and posterior parts
Frontal plane
Horizontal plane that runs from left to right, dividing the body into superior and inferior parts
Transverse plane (cross-section)
A vertical plane that divides the body or a body part into right and left portions
Sagittal plane
Specific sagittal plane that lies exactly in the midline
median plane (all others are parasagittal)
Cuts made along any plane that lies diagonally between the horizontal and vertical are called
oblique sections
Toward the head end or upper part of a structure or the body; above
superior
Away from the head end or toward the lower part of a structure or the body; below
inferior
Toward or at the middle of the body; on the inner side of
medial
away from the midline of the body; on the outer side of
lateral
closer to the origin of the body part or the point of attachment of a limb to the body trunk
proximal
farther from the origin of a body part or the point of attachment of a limb to the body trunk
distal
on the same side
ipsilateral
on opposite side
contralateral
toward or at the front of the body; in front of
anterior
toward the back of the body; behind
posterior
toward or at the body surface
superficial
away from the body surface; more internal
deep
a joint in which bones are united only by a ligament
syndesmosis
two types of cartilaginous joints are
synchondroses and symphyses
a joint where hyaline cartilage unites the bones
synchondrosis
a joint where fibrocartilage unites the bones
symphysis
freely movable joint with a cavity and a capsule
synovial joint
spongy cartilage in synovial joints
articular cartilage
the capsule of a synovial joint; consists of an outer layer of fibrous connective tissue and an inner synovial membrane
articular capsule
fluid secreted by the synovial membranes of the freely movable joints of the body; lubricates the joints surfaces and nourishes that articular cartilages.
synovial fluid
a disc of fibrocartilage in some synovial joints; occurs in joints whose articulating bone ends have somewhat different shapes
articular disc; meniscus
a fibrous sac lined with synovial membrane and containing synovial fluid; occurs between bones and tendons where it acts to decrease friction during movement
bursa
essentially and elongated bursa; it occurs only on tendons that are subjected to friction
tendon sheath
sliding the flat surfaces of two bones across each other
gliding
decreasing the angle between two bones
flexion
increasing the angle between two bones
extension
moving a limb away from the body midline
abduction
moving a limb toward the body midline
adduction
moving a limb or finger so that it describes a cone in space
circumduction
turning a bone around the longitudinal axis
rotation
rotating toward the medial plane
medial rotation
rotating away from the medial plane
lateral rotation
occurs when the forearm rotates laterally so that the palm faces on anteriorly (on its back)
supination
occurs when the forearm rotates medially so that the palm faces face down
pronation
roll ankle inward
inversion
roll ankle outward
eversion
point foot down
plantar flexion
point foot up
dorsiflexion
adjoining bones do not move around a specific axis
nonaxial
movement occurs around a single axis
uniaxial
movement can occur around two sacs; thus, the joint enables motion along both the frontal and sagittal planes
biaxial
movement can occur around all three axes and along all three body planes: frontal, sagittal, and transverse
multiaxial
synovial joints are classified as …. (6)
plane, hinge, pivot, condylar, saddle, and ball-and-socket
stability of synovial joints depends on three factors
shapes of articular surfaces, number and position of ligaments, muscle tone
a ligament can stretch only about ___ % beyond its normal length before it snaps
6%
an outer layer of dense, irregular connective tissue surrounds the whole skeletal muscle
epimysium
surrounding each fascicle is a layer of fibrous connective tissue called
perimysium
muscle fibers are separated into small groups called
fascicle
within a fascicle, each muscle fiber is surrounded by a fine sheath of loose connective tissue consisting mostly reticular fibers
endomysium
the connective tissue structure that joins skeletal muscle to bones
tendon
the attachment of the muscle on the less movable bone is called
origin
the attachment of the muscle on the more movable bone called
insertion
fibrous sheet connecting a muscle to the body part it moves
aponeurosis
a motor neuron and all the muscle fibers it innervates are called a
motor unit
the average number of muscle fibers in a motor unit
150
the addition of motor units to accomplish a movement is called
recruitment
skeletal muscle fibers can shorten by up to ____ of their resting length as they contract
1/3rd
when the effort arm is longer than the load arm, the lever operates at a mechanical advantage; when the effort arm is shorter than the load arm, the lever operates at a mechanical disadvantage
law of levers
arrangement of the elements is load-fulcrum-effort
first-class lever
arrangement of the elements is fulcrum-load-effort
second-class lever
arrangement of the elements is load-effort-fulcrum
third-class lever
all muscles develop from the _____ layer
mesoderm germ
in a development based scheme, muscles are organized into four groups
muscles of the visceral organs, pharyngeal arch muscles, axial muscles, and limb muscles
a muscle that has the major responsibility for producing a specific movement is the
prime mover (agonist)
muscles that oppose or reverse a particular movement are
antagonists
help the prime movers either by adding a little extra force to the movement being carried out or by reducing undesirable extra movements that the prime mover may produce
synergists
muscle that immobilizes one or more bones, allowing other muscles to act from a stable base
fixator
