unit 15 Flashcards
A muscle can return to its original length when relaxed due to a quality of muscle tissue called
elasticity
Muscle tissue also has the quality of
extensibility
contractility
allows muscle tissue to pull on its attachment points and shorten with force
Differences among the three muscle types include the microscopic organization of their contractile proteins
actin and myosin
skeletal muscle fibres
multinucleated structures that compose the skeletal muscle
cardiac muscle fibres
each have one to two nuclei and are physically and electrically connected to each other so that the entire heart contracts as one unit (called a syncytium)`
how many nuclei in smooth muscles
one
skeletal muscles are located
throughout the body at the openings of internal tracts to control the movement of various substances. These muscles allow functions, such as swallowing, urination, and defecation, to be under voluntary control. Skeletal muscles also protect internal organs (particularly abdominal and pelvic organs) by acting as an external barrier or shield to external trauma and by supporting the weight of the organ
how do skeletal muscles contribute to homeostasis of the body
- generating heat
- muscle contraction requires energy, when ATP is broken down, gives off heat
- shivering causes skeletal muscles to produce heat
various integrated tissues in skeletal muscle
skeletal muscle fibres, blood vessels, nerve fibres, and connective tissue
epimysium
- dense, irregular connective tissue wrapped around each muscle
- allows a muscle to contract and move powerfully while maintaining its structural integrity
- also separates muscle from other tissues and organs in the area, allowing the muscle to move independently
What are muscle fibers organized into within each skeletal muscle
bundles called fascicles
what is the connective tissue that surrounds the fascicle?
- perimysium.
what is the purpose of fascicular organization in muscles of the limbs?
allows the nervous system to trigger specific movements by activating a subset of muscle fibers within a fascicle.
What connective tissue surrounds each individual muscle fiber inside a fascicle?
- Each muscle fiber is surrounded by the endomysium
- The endomysium is made of collagen and reticular fibers.
- The endomysium contains extracellular fluid and nutrients to support the muscle fiber
how do skeletal muscles work with tendons to move bones?
Collagen in the muscle’s tissue layers (mysia) intertwines with tendon collagen, which then fuses with the bone’s periosteum, transferring muscle tension to pull the bone.
how are skeletal muscle fibres stimulated to contract
Each muscle fiber is supplied by an axon branch from a somatic motor neuron, which signals the fiber to contract
How is skeletal muscle contraction different from cardiac and smooth muscle?
Skeletal muscle contraction only occurs through signaling from the nervous system, unlike cardiac and smooth muscle.
pivot
C1 and C2 vertebrae, proximal radio lunar joint
hinge
-uniaxial joints
- allows for flexion, extension
- knee, elbow, ankle
- interphalangeal joints of fingers and toes
condyloid
- biaxial joints
flexion and extension, adbduction/adduction, circumduction
= metacarpophalangeal (knuckles) joints, radicarpal joints of wrists, metatarsophalangeal joints of toes
saddle
- biaxial
- flex/extend, abduction/adduction, circumduction
- first carpometacarpal joint of thumb, sternoclavicular joint
plane
- inversion/eversion, flex/extension, lateral flexion of vertebral column
- intertarsal joints of foot
ball and socket
- mulitaxial joint
- flex/entension, auction/add, circumduction, medial/lateral rotation
- shoulder joint, hip joint
dorsiflexion
moving the toes up
plantar flexion
toes down, heel up
inversion
angle foot towards midline
eversion
turns bottom of the foot away from midline
protraction
of the scapula: when shoulder is moving forward
retraction
- scapula being pulled posteriorly and medially
protraction in mandible
lower jaw is pushed forward
retraction of mandible
pulls lower jaw backward
depression and elevation
downward and upward movement of scapula or mandible
