Intro to muscles (general myology) Flashcards
What are the 4 characteristics of muscle cells?
- Irritability (“Electrical Excitability”)
- Contractility
- Extensibility
- Elasticity
What are the 3 types of muscle tissue (describe each)
- Skeletal: striated, voluntary
- Smooth: non-striated, involuntary, visceral
- Cardiac: striated, specialized, involuntary
What is muscle fascia?
- Dense irregular connective tissue
- completely surrounds muscle
- skeletal muscle found deep to it
What are the extensions of the muscle fascia called?
Epimysium
Muscle fiber =
Muscle cell
Each muscle fiber is covered by:
endomysium
Bundles of muscle fibers are called:
Fascicles
Each fascicle is covered by
Perimysium
Whole muscle is made up of:
a group of fascicles
Whole muscle is covered by:
epimysium
Each muscle fiber is made up of bundles of:
myofibrils
Each myofibril is covered by:
sarcoplasmic reticulum
Deep to endomysium, muscle fiber is covered by:
sarcolemma
Each myofibril is made up of:
Myofilaments (proteins)
Within each sarcomere, each myofibril has:
3000 actin (thin) myofilaments
1500 myosin (thick) myofilaments
During contraction of muscle what happens to actin and myosin?
They overlap!
What is a sarcomere?
The microfunctional unit of a muscle
Describe a sarcomere
- Cross striations
- Dark (A) Bands: Actin+myosin
- Light (I) Bands: Actin ONLY
- middle: H zone + M Line (protein bands)
- Ends: Z discs
- Cross bridges (50 pairs)
- Surrounded by SR
- (Transverse) T-tubules: allow APs to spread quickly throughout muscle
Motor Unit =
Gross Functional Unit of the muscle (motor neuron + muscle fiber)
Motor unit is found at the:
myoneural junction
skeletal muscle contraction principle:
all or none
smooth muscle contraction principle
peristalsis
Neuromuscular Junction (NMJ):
Synaptic end bulb + motor end plate
Muscle Fiber Shapes:
- Longitudinal (Parallel): rectus abdominis
- Fusiform: Biceps
- Unipennate: flexor pollicis longus
- Bipennate: triceps
- Multipennate: deltoid
- Circular: around mouth, eyes
- Radiate (Triangular/Convergent): pec major
How do you name a muscle?
- Action
- Direction of fibers
- Location
- Size
- # origins
- Shape
- origin/insertion
Origin:
Proximal end (red)
Insertion:
Distal end
Belly (Head):
Fleshy or meaty part
Aponeurosis:
Broad, flat, tendon
Agonist:
Prime mover, Main action muscle
Antagonist:
Opposing muscle
Synergist:
helps action of agonist
Synergist (Fixator):
Stabilizes to help agonistA
Atrophy:
Decrease muscle size due to inactivity
Hypertrophy:
Increase muscle due to activity
Describe tendons.
- Extensions of muscle belly
- Epimysium, perimysium and endomysium
- Dense, regular connective tissue
- Parallel bundles of collagenous fibers
- attaches muscle to bone (at periosteum)
- may/may not have synovial sheath
Describe ligaments.
- attach bone to bone
- dense regular (or irregular) connective tissue
- mostly parallel collagenous fibers (some elastic)
- attaches to bone’s periosteum
- important for jnt stability
- jnt (fibrous) capsules: strength/stability
- certain lvl of flexibility for mvmt
What is isometric exercise?
- no jnt or functional mvmt
(pulling an object attached to the ground)
What is an isotonic exercise?
- fixed resistance, variable speeds (progressive resistive exercise: PRE)
(at the gym, bicep curls)
What is an isokinetic exercise?
- constant speed (degrees/sec) + accomodating resistance (max load at each point of jnt’s ROM)
What are the 2 types of contraction?
Concentric: muscle shortens
Eccentric: muscle lengthens
Muscle spindle function:
stretch + speed of stretch
(in muscle belly)
Golgi tendon organs function:
Tension
