week 6 (joints, movement & skeletal muscle, smooth and cardiac muscles) Flashcards
skeletal muscle
Muscles are attached to bones by tendons at their origins and insertions. Skeletal
muscles produce movements by pulling on bones.
Those skeletal muscles that produce movements do so by exerting force on tendons, which in turn pull on bones
or other structures (such as skin)
Because
each skeletal muscle fiber arises during embryonic development from
the fusion of a hundred or more small mesodermal cells called myoblasts
each mature skeletal muscle fiber has a
hundred or more nuclei. Once fusion has occurred, the muscle fiber loses
its ability to undergo cell division. Thus, the number of skeletal muscle
fibers is set before you are born, and most of these cells last a lifetime
Skeletal muscle also contains
connective tissues surrounding muscle fibers, and blood vessels and
nerves
origin
the attachment of a muscle’s tendon to the stationary bone is called the
origin is usually proximal
inseration
the attachment of the muscle’s other tendon to the movable bone
insertion distal
the insertion is usually pulled toward the origin
tendons
attach to muscle and secure the muscle to the bone
synvoial joint
The bones forming the joint have
a synovial cavity and are united by the dense irregular connective
tissue of an articular capsule, and of en by accessory ligaments
synvoial cavity
joint cavity between
the articulating bones. Because the synovial cavity allows considerable movement at a joint, all synovial joints are classified functionally
as freely movable
articular cartilage
The bones at a synovial joint are
covered by a layer of hyaline cartilage called
articular capsule
or joint capsule surrounds a synovial joint, encloses the synovial cavity, and
unites the articulating bones. The articular capsule is composed of two layers, an outer fibrous membrane and an inner synovial
membrane
synvoial membrane
is composed of areolar connective tissue with elastic fibers. At many synovial joints the synovial membrane includes accumulations of adipose tissue, called articular fat pads
fibrous membrane
of dense irregular connective tissue (mostly collagen fibers) that attaches to the periosteum of the articulating bones. In fact, the fibrous membrane is literally a thickened continuation of the periosteum between the bones.
The flexibility of the fibrous
membrane permits considerable movement at a joint, while its great tensile strength (resistance to stretching) helps prevent the bones from dislocating, the displacement of a bone from a joint.
The fibers of some fibrous membranes are arranged as parallel bundles of dense regular connective tissue that are highly adapted for resisting strains
ligament
is one of the principal mechanical
factors that hold bones close together in a synovial joint
synvoial fluid
Synovial
fluid consists of hyaluronic acid secreted by synovial cells in the
synovial membrane and interstitial fluid filtered from blood plasma.
It forms a thin film over the surfaces within the articular capsule. Its
functions include reducing friction by lubricating the joint, absorbing
shocks, and supplying oxygen and nutrients to and removing carbon
Synovial fluid also
contains phagocytic cells that remove microbes and the debris that
results from normal wear and tear in the joint
dioxide and metabolic wastes from the chondrocytes within articular
cartilage
menisci
crescent-shaped
pads of fibrocartilage lie between the articular surfaces of the bones
and are attached to the fibrous capsule
1) shock absorption; (2) a better fit between articulating bony surfaces; (3) providing adaptable surfaces for combined
movements; (4) weight distribution over a greater contact surface;
and (5) distribution of synovial lubricant across the articular surfaces
of the joint.
hinge joint
in which the articular surfaces are molded to each other in such a manner as to permit motion only in one plane
it is like a line shape and then another bone forming to it
examples: elbow, knee, interphalangeal (IP) joints of the hand and foot and the tibiotalar joint of the ankle
ball and socket joint
Ball-and-socket joint, also called spheroidal joint, in vertebrate anatomy, a joint in which the rounded surface of a bone moves within a depression on another bone, allowing greater freedom of movement than any other kind of joint
example: shoulder nad hip joints
pivot joint
Pivot joints, also known as rotary joints, are a type of synovial joint that permit axial rotation. The moving bone rotates within a ring formed by the concave surface of a second bone and an adjoining ligament
example would be the 2nd vetrebrea and neck bone and joint of wrist
abduction
the movement of a bone away from the midline
adduction
is the movement of a bone towards midline
circumduction
is movement
of the distal end of a body part in a circle
internal/medial rotation
anterior surface of a bone of the limb is turned toward the midline, the movement is called medial (internal) rotation
external/lateral rotation
anterior surface of the
bone of a limb is turned away from the midline, the movement is
called lateral (external) rotation
extension
Increase in angle between articulating bones,
flexion
Decrease in angle between articulating bones,
usually in sagittal plane
joint
is a point of contact between two bones, between
bone and cartilage, or between bone and teeth
fibrous joint
There is no synovial cavity, and the bones
are held together by dense irregular connective tissue that is rich in
collagen fibers.
cartilaginous joint
There is no synovial cavity,
and the bones are held together by cartilage
synarthrosis
An immovable
joint
amophiarthrosis
A
slightly movable joint
diarthrosis
A freely movable
joint. The plural is diarthroses. All diarthroses are synovial joints.
They have a variety of shapes and permit several different types of movements.
sutures (fibrous joint)
is a fibrous joint
composed of a thin layer of dense irregular connective tissue; sutures
occur only between bones of the skull
They are
immovable or slightly movable
head bons
syndesmoses (fibrous joint)
is a fibrous joint in which there is a greater
distance between the articulating surfaces and more dense irregular
connective tissue than in a suture
between tibia and fibula
interosseous membranes (fibrous joint)
which is a substantial sheet of dense irregular connective tissue that binds neighboring long bones and permits slight
movement
provide an increased attachment surface for muscles that produce movements of the digits of the
hand and foot.
synchondroses (cartilaginous joint)
is a cartilaginous joint in which the connecting
material is hyaline cartilage and is slightly movable
the joint between the first rib and the manubrium of the sternum
symphyses (cartilaginous joint)
is a
cartilaginous joint in which the ends of the articulating bones are
covered with hyaline cartilage, but a broad, flat disc of fibrocartilage
connects the bones
and at the intervertebral joints between the bodies
of vertebrae
three types of muscle fibres
smooth, caridiac and skeletal
excitability of muscules
the ability to respond to a stimulus, which may be delivered from a motor neuron or a hormone
a property of both muscle and nerve cells that was is the ability
to respond to certain stimuli by producing electrical signals called
action potentials (impulses). Action potentials in muscles are referred to as muscle action potentials; those in nerve cells are called
nerve action potentials.
contractility of muscules
Contractility is the ability of muscle cells to forcefully shorten. Contractility allows muscle tissue to pull on its attachment points and shorten with force
the ability of muscular tissue to
contract forcefully when stimulated by an action potential. When a
skeletal muscle contracts, it generates tension (force of contraction)
while pulling on its attachment points.
elasticity of muscles
the ability to stretch a muscle to reach its full range of movement without restriction
extensibility of muscules
Extensibility is the ability of a muscle to be stretched
is the ability of muscular tissue to
stretch, within limits, without being damaged. The connective tissue
within the muscle limits the range of extensibility and keeps it within
the contractile range of the muscle cells. Normally, smooth muscle
is subject to the greatest amount of stretching. For example, each
time your stomach fills with food, the smooth muscle in the wall is
stretched. Cardiac muscle also is stretched each time the heart fills
with blood.
motor unit
made up of a motor neuron and all of the skeletal muscle fibers, also known as sarcomere innervated by the neuron’s axon terminals. Groups of motor units often work together as a motor pool to coordinate the contractions of a single muscl
somatic motor nervous system
somatic nervous system, or voluntary nervous system is the part of the peripheral nervous system associated with the voluntary control of body movements via skeletal muscles
somatic motor nervous system can not happen withoutthe use of skeletal muscles
