Exercise Science Muscles Unit

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Contractibility

Contractibility

Muscles can contract/flex by having filaments move against each other (concentric contraction)

Extensibility

Muscles can extend by having the filaments move against each other (eccentric contraction)

Elasticity

Muscles can stretch past original length and return to initial length when stress is removed

Atrophy

When muscle fiber is reduced due to lack of use or nerve disease (nutrients and building blocks of the muscle fiber are slowed/stopped)

Hypertrophy

When muscle fiber is increased due to stress on the muscle (increase of availability of building blocks)

Muscles

Contractile tissue connected to bones and used in movement and other body functions (controlled by nerve stimulus and fed by capillaries)

Smooth

Type of muscle attached to internal organs, under involuntary control, function is to move substances through the body, not striated as the muscles squeeze the vessels (line blood vessels to move blood and hollow organs to move food)

Cardiac

Heart muscle under involuntary control, function is to produce forces of heart to circulate blood, straited due to force from sarcomeres

Skeletal

Type of muscle attached to bones through tendons, under voluntary control, function is to produce movement and support body weight, straited with force from sarcomeres

Epimysium

Fascia tissue that surrounds an entire muscle structure that is continuous with the tendon

Perimysium

Fascia tissue surrounding groups of muscle fibers into strands, increasing the tensile strength

Endomysium

Fascia tissue surrounding individual muscle fiber

Muscle Fiber

Elongated single muscle cell, made up of myofibrils and the number of nuclei changes (skeletal fibers have multiple while smooth and cardiac have one)

Myofibril

Thin, small fibers within a muscle fiber, made up of sarcomeres

Sarcomere

Functional unit within a muscle fiber, contains proteins that bind together to contract a muscle

Myosin

Protein of thick filament within muscle cells (stitch-like appearance)

Actin

Protein of thin filament within muscle cells (line the sarcomere with the z-line)

Origin

Where muscle attaches with tendon to stationary bone (likely proximal)

Insertion

Where muscle attaches with tendon to moving bone (likely distal)

Deltoid

Anterior shoulder muscle that raises the arm, origin at scapula/clavicle, insert at lateral humerus

Pectoralis

Anterior muscle that controls shoulder movement, origin at sternum/clavicle/anterior rib, insert at humerus

Iliopsoas

Anterior muscle that pulls thighs upward, origin at lumbar/ilium, insert at inner femur

Sartorius

Anterior leg muscle that pulls thighs upward and bends knee, origin at ilium, insert at medial tibia

Tibialis Anterior

Anterior lower leg muscle that pulls toes towards shin, origin is lateral tibia, insert at cuneiform(tarsal)/metatarsals

Abdominus Rectus

Anterior trunk muscle that pulls trunk forward (crunches), ab muscles

External Oblique

Anterior trunk muscle that allows for rotational movements (sides of body), origin at lower ribs, insert at ilium

Biceps brachii

Anterior upper arm muscle that controls movement of the lower arm, origin at scapula, insert at radius/ulna

Trapezius

Posterior shoulder muscle that raises the shoulder and allows for powerful shoulder movement, origin at cervical/thoracic/skull, insert at clavicle/scapula

Triceps brachii

Posterior arm muscle that controls movement in the lower arm, origin at scapula/humerus, insert at ulna

Latissimus Dorsi

Posterior back muscle that pulls arms backwards and rotates arms inward, origin at sacrum, ilium, thoracic/lumbar, insert at humerus

Gluteus Maximus

Posterior butt muscle that pulls thighs backwards and extends hips, origin at posterior ilium/sacrum/coccyx, insert at lateral femur

Hamstrings

Posterior thigh muscle group (Biceps femoris, semitendinosus, semimembranosus) that pull lower leg backwards and up, flexes the knee, origin at ischium (all three) and femur (biceps femoris), insert at fibula/lateral tibia (biceps femoris) and medial tibia (other two)

Gastrocnemius

Anterior calf muscle that straightens the foot, the more superior calf muscle, origin at posterior femur, insert at calcaneus (tarsal) through Achilles tendon

Soleus

Anterior calf muscle that straightens the foot, the more inferior calf muscle, origin at posterior tibia/fibula, insert at calcaneus

Erector Spinae

Back muscle that straightens the body, origin at ribs/cervical/lumbar/thoracic/ilium, insert at ribs/cervical/lumbar/thoracic

Quadriceps

Anterior thigh muscle group (vastus lateralis, vastus intermedius, vastus medialis, rectus femoris) that straighten the knee joint, origin at femur (vastus muscle groups) and the ilium (rectus femoris), insert at patella and upper tibia