Muscles Flashcards
1) Skeletal
Voluntary muscle
Movement, heat production, posture
2) Smooth
Involuntary muscle
ie. Swallowing
Controlled by nervous system
Autonomic nervous / endocrine system
3) Cardiac
Only in the heart 🫀
Electrical conduction
Muscle cells are..
Striated
Epimysium
Encases ENTIRE muscle
Holds fascicles together
Perimysium
Covers fascicle (group of muscle fibers)
Endomysium
Covers the muscle cell (fiber)
Fascia
Connective tissue (fibrous)
Surrounds epimysium and tendon
Tendon connects
Muscle to bone
Tendons covered by
Tendon sheaths (lubrication)
Sheaths are lined with synovial membrane
Tendons glide within sheath during movement
Skeletal muscle
Functions: Movement, heat production, posture
Excitability
Irritability
Ability to respond to nerve signals
Skeletal muscle
Functions: Movement, heat production, posture
Contractibility - shorten
Extensibility - stretch
Muscle fiber
Surrounding is sarcolemma =
Cell membrane
Sarcoplasm =
Cytoplasm
T tubules
Across sarcolemma in muscle fiber
T tubules allow electrical impulses to enter for contraction
Myofibril (cytoskeleton)
Inside muscle fiber
Thick myofilaments
Myosin (protein)
Thin myofilaments
*Actin
Troponin
Tropomyosin
(Proteins)
Sarcomere
Contractile unit of muscle in myofibril
Z disk to a disk
Ca++ storage in..
Endoplasmic reticulum
How does a contraction work?
Excitation of the sarcolemma -> T tubules -> sarco. reticulum release Ca++ into sarcoplasm -> Ca++ binds to troponin (thin) = chemical reaction = contraction
Mm at rest
Ca++ channels are closed
Tropomyosin covers active sites on actin
Muscle structure
Connective tissue
Muscle fibers
Myofibrils
Strain
Caused by: overexertion, trauma, no warming up (flexibility)
Symptoms: pain (myalgia), may be weakened
Fibromyositis
Myositis
Inflammation of muscle and tendon
Inflammation of mm, result of a strain
Torn Rotator Cuff (RTC)
Tear in tendons of cuff mm
Hold head of humerus in glenoid fossa
RTC tear causes and symptoms
Traumatic injury
Chronic degeneration
May hear tearing sound (crepitus)
Acute pain
LOM in abduction and flexion of shoulder
Tendonitis
Microtrauma
Many actually tendinosis, tenosynovitis
RSI
Load > tissue tolerance
Micro -> Macrotrauma
Tetanus
Mm spasm, lockjaw, can cause fracture or tear
Toxins from bacterium 🦠
Can be from any skin puncture
Hernia
Protrusion of organ (sm intestine) through abdominal muscles/fascia
Muscular Dystrophy
Duchenne type
Muscle atrophy
Mutation on X chromosome
