Anatomy & Physiology: Muscular System

Voluntary Muscles

Skeletal Muscle

Striated

Skeletal Muscle

Parallel/Linear

Shape of Skeletal Muscle

Branched

Shape of Cardiac Muscle

Spindles

Shape of Smooth Muscle

Mono-nucleated 

Cardiac & Smooth Muscle

Has intercalated discs

Cardiac Muscle

Epimysium

outermost layer that covers the entire muscle

Perimysium

Second outermost layer; covers fascicle

Endomysium

Innermost layer; the individual muscle fiber(s)

Sarcomere

Contractile unit of myofibril in striated muscles

Muscle Fatigue

Loss of ability for muscle to contract

Isotonic

Flex; muscles length changes after contraction

Isometric

Hold; muscle length does not change despite contraction

Latent

Brief delay between time of stimulation and the beginning of the contraction

Muscle Tone

“contractions/appearance of the muscle at rest'“

Origin

End of skeletal system; fastened to immovable/fixed joints

Insertion

Where muscle connects to movable part on other side of a joint

Agonist (Prime Mover)

Muscles providing particular body movement

Synergist

Muscles assisting action of the prime mover

Antagonist

Muscles that oppose the prime mover

Troponin

Actin

Thick protein filaments; globular structure with binding sites

Myosin

Thick protein filaments; two twisted strands with globular akimbo parts

Muscle Fiber

Single cell that contracts in response to stimulants; thick, elongated fiber with round ends (relax)

Tendon

Attaches muscle to bone

Myofibrils

Thread-like fibers that are parallel to each other

How muscles are named

Relative size, shape, location, action, number of attachments, and/or direction of the fibers

Orbicularis Oculi

Skin around the eyes; BLINKING

Orbicularis Oris

Skin around the mouth; CLOSE & PROTRUDE LIPS

Buccinator

In the lateral wall of oral cavity; COMPRESS CHEEKS INWARD

Deltoid

Shoulder; ABDUCT ARM/ETENDS AND FELXES HUMEROUS

Pectoralis Minor

Under chest; PULL SCAPULA ANTERIORLY & DOWN, SLIGHTLY RAISES RIBS

Serratus Anterior

Underarm/oblique region; HUGS

Trapezius

Shoulder connection to neck; ROTATE SCAPULA, MOVE SHOULDERS, and PULL SCAPULA

Acromion Process of Scapula

Bony projection of clavicle; ARTICULATES WITH CLAVICLE TO ABDUCT ARM, SHRUGGING, LIFTING

Rhomboid Major

Lower shoulder blade; SLIGHTLY RAISE ARMS & ADDUCT SCAPULA

Pectoralis Major

Chest; PULL ARM CROSS CHEST/ADDUCTS

Latissimus Dorsi

Sides of back; EXTEND/ADDUCT ARM, PULSS SHOULDERS POSTERIORLY

External Oblique

Outermost?; RUSSIAN TWISTS

Rectus Abdominus

CRUNCHING MOTION

Transverse Abdominus

Innermost layer; SIDE-TO-SIDE ROTATION

Internal Oblique

RUSSION TWIST MOTION

Iliacus

Hips; FLEXES THIGH

Psoas Major

INNER HIP; FLEXES THIGH

Gracilis

Inner thigh; ADDUCTS THIGH AND ROTATES LOWER LEG MEDIALLY

Rectus Femoris

Medial quad; EXTENDS LEG AT KNEE

Sartorius

Hip-to-knee region; FLEX THIGH

Adduction

Moving toward the midline

Abduction

Moving away from midline