Muscular System Flashcards
Muscular system is only composed of..
skeletal muscle (not cardiac or smooth)
Skeletal muscle cells are called..
fibers
Fascicle is a..
group of fibers
Whole muscle is a..
group of fascicle
CT components of skeletal muscle
- Fascia
- Tendons
- Aponeuroses
Fascia
connective tissue enclosing muscle of a group of muscles
Epimysium
surrounds entire muscle of fascia
Perimysium
wraps all of the fascicles
Endomysium
wraps each individual muscle fiber
Tendons
- connective tissue that attaches muscle to bone
- extensions of epi, peri, and endomysium covering the muscle
Each myofibril is divided into contractile units called….
called sarcomeres.
the sarcomeres join end to end to form the myofibril
Aponeurosis
sheet-like tendon, anchors muscle to connective tissue covering of a bone (found in skull)
Skeletal muscle fiber structure
long, cylindrical multinucleate cells
Parts of skeletal muscle fiber structure
- Sarcolemma
- Sarcoplasm
- T-tubules
- Sarcoplasmic reticulum
Sarcolemma =
Specialized muscle cell plasma membrane
Sarcoplasm =
cytoplasm of muscle fibre
Myofibrils
- intracellular structures
- Organelles that form the muscle fiber
- Made up of bundles of myofilaments
Myofilaments make up myofibrils and come in 2 forms
- thin filaments
- thick filaments
Thin filaments composed of
- actin (functions in contraction)
- tropomyosin (stabilizes actin until contraction occurs)
- troponin (regulate contraction by binding to calcium and actin)
Thick filaments composed of..
myosin (rod like tail and 2 globular heads)
Thick filaments
are attached to Z band of sarcomere by titin and the globular head binds towards actin forms cross bridge
The myofilaments create ___ and ____ bands of the sarcomere
dark; light (provide muscle w striated appearance)
Each sarcomere contains ..
- A band
- H zone
- I band
- Z discs
- M line
- T tubules
“A” band
spans the length of the thick filament, its dark and composed of action and myosin
H zone
at centre of the A band (light and composed of myosin)
I band
light and composed of actin, Titian and Z disk
Z discs are in the centre of _ band
I
Z discs
connect sarcomeres (2 Z discs/1 sarcomere). thick filaments are connected to the Z disk by Titin protein
M line
where myosin tails (thick myofilaments) connect to one another art the centre of the sarcomere
Myofibrils
sarcomeres joined end to end at Z discs
T-tubules (transverse tubules)
continuations of sarcolemma that extend deep into fiber
What t-tubules do
directly encircle myofilaments of myofibrils at junction of A and I bands
Sarcoplasmic reticulum
Smooth ER with terminal cisternae (expanded regions near the T tubules)
The origin of the muscle is on..
the stationary bone
The insertion of the muscle is on the..
moving bone
Agonists are the..
major muscle producing the movement
Synergists act to..
help the agonist by either providing extra force that’s needed or preventing undesirable effects by the agonist
Antagonists act to oppose the..
action of agonist (contraction inhibited when agonist contracts)
Lever system
bone and muscle interact at joint to accomplish moving
The lever is the..
bone
The fulcrum is the..
joint
Effort is the..
contraction of agonist
Resistance opposes..
movement of the load
Flexors
decrease angle between 2 bones
Extensors
increase angle between 2 bones
Abductors
move limb away from midline
Adductors
move limb toward midline
Deltoid
triangular shape of muscle
Trapezius
trapezoid shape of muscle (no two sides parallel)
Break down origin and insertion of sternocleidomastoid
-origin: sterno =sternum
cleido = clavicle
-insertion: mastoid - massed process of temporal bone
To describe relative size we use..
- maximus
- medius
- minimus
Direction of fibers
- rectus (straight) ||
- transversus (90 degree angle relative to a reference line)
- external (not at a 90 degree angle or straight relative to reference line) \ //
Characteristics of skeletal muscle
- under voluntary control
- striated
- attached primarily to bone
- produces bodily movements
- release heat as a byproduct of contraction
Triads
T-tubules associated with 2 terminal cisternae
Sarcomeres are the ..
contractile unit of muscle
Myofibrils are divided intro..
sarcomeres
Muscles and bone can produce movement by ..
- muscles pulling on bone when they contract (origin/insertion)
- using group action (agonists, antagonists, and synergists)
- forming lever systems
Number of origins used to describe muscles
- Biceps brachii: 2 points on the scapula
- Triceps brachii: 3 points on the scapula and the humerus
- Quadriceps femoris: 4 points on the ileum and the femur
