Skeletal Muscular System Flashcards
5 Functions of Skeletal Muscles
1 produce skeletal mvmt
2 maintain posture + body position
3 support soft tissue + visceral organs
4 regulate entry + exit of material thru orifices
5 maintain body temp thru contraction and use of energy
Tissues of Skeletal Muscle
EPIMYSIUM dense irregular connective tissue (seperates muscle fr surrounding tissues/organs + connected to deep fascia)
PERIMYSIUM connective tissue fibers w collagen, elastic fibers, + numerous blood vessels +nerve supply (divides muscle into internal compartments w fascicles)
ENDOMYSIUM reticular fibers w myosatellite cells scatered bw endomysium + muscle fibers[surrounds each skeletal fiber (cell) + supportsthe capillaries for each fiber]
Fascicle
Bundles of muscle cells surrounded by a Perymysium membrane and Endomytrium plasma
APONEUROSES
tendons that form thick, flattened sheets
at the end of the muscle, collargen fibers of epimysium, perimysium, and endomysium come together to form a _______.
TENDON
collagen fibers of tendons are continuous w periosteum and matrix of bone to which it attaches + makes extremely strong bond
Nerves + Blood Vessels of Skeletal Muscles
enters epimysium, branches out through perimysium + attached to individual muscle fibers in endomysium
provides control over contraction
NEUROMUSCULAR JUNCTION
NMJ
site where chem communicatin bw a neuron and skeletal muscle fiber occurs
NMJ is made up of axon terminal of neuron, regiin of plasma membrane called Motor End Plate, narrow space bw called synaptic cleft, and membrane of muscle fiber
SARCOLEMMA
plasma membrane of skeletal muscle
SARCOPLASM
cytoplasm w/in sarcolemma
Unique Qualities of SKELETAL MUSCLE FIBERS
- larger than other cells (100 um and 30 cm-16in)
- multinucleate (can contain hundreds in the sarcolemma)
- Transverse Tubules (T Tubules) that extend on sarcoplasm and conduct electrical impulses to stimulate contractions
3 Types of Muscles
Skeletal muscle - only type of muscle w voluntary control
Smooth muscle
Cardiac muscle
Attachment sites of Skeletal Muscles
skins, eyes, bone
Types of Muscle Contractions
1 Reflexive 2 Tonic 3 Phasic 3a Isometric 3b Isotonic
Reflexive Contractions
controlled by Autonomic Nervous System but can be temporarily override consciously
ex) diaphragm is controlled bt ANS but if you think about ur breathing, you can control the contraction.
Tonic Constraction
Remain in a state of contraction for long periods of time. Mostly for posture and stability maintenance
ex) muscles of lower back hold us up and are resistant to fatigue
Phasic - Isometric Contraction
generates force while maintaining a constant length
ex) holding up a heavy box w arms - constant generating of contraction to keep it stabilized and up
Phasic - Isotonic Contraction
Concentric - muscle overcomes opposing force and shortens
Eccentric - force of a muscle is less than weight and lengthening occurs
9 Types of Movements
Flexion Extension Rotation Elevation Depression Pronation Supination Abduction Adduction
Flexion
action that decreases the angle bw 2 bones
ex) flexing the elbow shortens the angle bw humerus and forearms
Extension
increases the angle bw 2 bones
ex)
Rotation
spinning mvmt around axis
ex) turning head around axis of vertebral column
Elevation
upwards mvmt on vertical plane
ex) mvmt of mandible up to bite
Depression
mvmt of structure downwards
Pronation
rotational mvmt of joints (usually on hand or forearm so that palm faces posteriorly)
Supination
returns pronated hand to anatomical position
Abduction
moving a structure away fr midline
ex) raising arm away fr sides
Adduction
moving a structure towards the midline
