Muscular System Lecture Notes

Comprehensive vocabulary flashcards covering muscle attachments, contractions, functional muscle groups, microscopic sarcomere anatomy, connective tissue coverings, and neuromuscular innervation from the lecture notes.

Fixator

A muscle that steadies the proximal parts of the limb.

Direct attachment

Muscle attachment to bones via short connective tissue (CT) fibers.

Indirect attachment

Connective tissue (CT) that extends beyond the end of muscle fibers, creating cordlike tendons and flat aponeurosis sheets.

Tendon

A cordlike indirect connective tissue attachment that concentrates force in a limited area.

Aponeurosis sheets

Flat indirect connective tissue attachments that spread force over wide areas.

Isometric Contraction

A contraction resulting in no change in muscle length, causing no movement and providing stabilization.

Concentric Contraction

A contraction involving a change in muscle length where the muscle shortens during movement.

Eccentric Contraction

A contraction involving a change in muscle length where the muscle lengthens during movement.

Prime mover (agonist)

The muscle primarily responsible for producing a specific movement.

Antagonist

Muscles that perform the opposite movement to the agonist, helping to stabilize and control movement.

Synergist

A muscle that complements the movement of the agonist, counteracts unwanted movement, and acts as a weaker actor performing the same movement.

Muscle fibers

Long, cylindrical, multinucleated cells.

Sarcolemma

The plasma membrane of a muscle fiber.

Sarcoplasma

The cytoplasm of a muscle fiber.

Sarcomere

The basic unit of muscle contraction composed of repeating segments bounded by Z lines.

Thin Filaments

Fine myofilaments attached to the Z line that extend toward the center of the sarcomere, composed of contractile actin, troponin, and tropomyosin.

Thick filament

Myofilaments at the center of the sarcomere that overlap thin filaments, composed of myosin and ATPase.

A Band

The dark bands corresponding to the full length of the thick filaments and the inner ends of the thin filaments.

H zone

The central portion of the A Band containing no filaments.

M band

A structure in the center of the H zone consisting of tiny rods that hold the thick filaments together.

I Band

Regions on either side of the A band that contain only thin filaments.

Titin

A myofibril protein that resists overstretching, holds thick filaments in place, unfolds when stretched, refolds when released, and becomes stiffer the more it uncoils.

Epimysium

A tough, dense, outer layer of connective tissue that surrounds the entire muscle.

Perimysium

Thick connective tissue that groups individual muscle fibers into fascicles.

Endomysium

A thin inner network of connective tissue surrounding individual muscle fibers in which the smallest nerves and capillaries are embedded.

Myotendinal junction

The junction where all three connective tissue layers (epimysium, perimysium, and endomysium) unite.

Motor end plate

The region on the sarcolemma where a single myelinated motor fiber ends.

Isotonic

Muscles that change in length to produce movement

Skeletal muscle is enclosed by what three CT layers

The epimysium, perimysium, and endomysium.