Lecture 4 Flashcards
Myology
Study of muscle
Muscle cells (fibers)
Only cell in the body that have property of contractility,.
Allows them to shorten and develop tension
3 types of muscle
Skeletal, smooth, cardiac
Skeletal muscle
Attaches to and moves the skeleton
Striped pattern
Voluntary control
75% water, 20% protein, inorganic salts, pigment, fat, carbs
Smooth muscle
founding the walls of hollow organs and blood vessels.
Not aligned, creating smooth appearance
Involuntary control
Syncytium
Syncytium
Connection between cells allows them to contract together
Cardiac muscle
Heart wall contractile tissue Has characteristics of both smooth muscle and skeletal muscle Striped involuntary control syncytium
6 criteria used to name muscles
- Shape
- Action
- Location
- division
- Size relationship
- direction of the fibers
Shape
Deltoid, trapezius, rhomboid
Action
Flexor, extensor, adductor, pronator
Location,
anterior, intercostals, pectoralis major
Division
Bicep, tri cep, quad ricep
Size
Include the term Brevis (Short) , Longus (long)
Direction of the fibers
Transverse (sideways) Rectus ( updown)
Fasciculi
Bundle of muscle fibers
May run parallel to long axis muscle. Insert diagonally into a tendon running the length of the muscle.
Unipennate:
All fascicule insert on one side of a tendon
-semimembranosus
Bipennate-
fascicule insert on both sides of tendon
Multipennate
Convergence of several tendons- deltoid.
Longitudinal (strap)
Fascicule run parallel to the long axis of the muscle
Radiate
Fan our from a single attachment - pec major
Primary mover
A muscle whose contraction is primarily responsible for a particular movement
Antagonist
Oppose one another upon contraction
Located on opposite side of a joint
Fixator/stabilizer-
Muscle that immobilize a bone or joint near the organ of the prime mover so prime mover can act more efficiently
Gross Anatomy
Origin = less movable end of a muscle, proximal Insertion = more movable end of a muscle, distal Belly = Widest portion of a muscle, between its origin and insertion
Connective tissue 3 Layers:
Epimysium = whole muscle
Perimysium = bundle of muscle fiber
Endo mysium= a single muscle fiber
Myofibrils
Within muscle fiber, there are many myofibrils.
consist of large array of contractile protein
Striped
Sarcomere
Repeated area of a contractile protein, every section
Two major contractile proteins
Actin = (thin filament)
Myosin( thick filament)
Motor unit
Functional unit of a muscle
consists of a motor neurone and all the muscle fiber that motor neurone innervates
at spinal cord
Axon
Motor neurone extends from spinal cord to the target muscle which may be a few millimetres away or a few feet away
All-or none law
Once motor neuron receives a strong enough stimulus, an action potential is generated. All or none at all
Motor units can be slassfied in 2 ways
Slow twitch & fast twitch
3 types of metabolic characteristics
Slow twitch oxidative (SO)
Fast twitch oxidative-glycolytic (FOG)
Fast twitch glycolytic (FG)
Endurance athlete vs power athletes
Endurance athelte= more slow twitch
Power athlete = more fast twitch
Concentric
Muscle is shortening
Eccentric
Muscle is lengthening
Isometric
Muscle is stationary
Muscle Force-Velocity Relationship
when Maximally activated, faster a muscle shorten = less for it produces
Faster it lengthens, more force it produces
Power =
= force x velocity
Angle of muscle pull
MUScle act on bones about the joint to form a lever system . Must be at 90 degrees or stabilizing component of the force increases.
3 factors that affects the expression of strength by a muscle
- The initial length of the muscle fibers
- speed of shortening
- Angle of the muscle
Sarcopenia
Age-related loss of skeletal muscle mass, strength, and function.
