ANAPHY-PRELIMS (1)

Muscular system

The system in the body responsible for all types of body movement.

Skeletal muscle

The dominant tissue of the body responsible for voluntary movement and attached to the skeleton.

Connective tissue

Tissue that surrounds and bundles muscle fibers.

Smooth muscle

Muscle found in the walls of hollow organs, such as the stomach and bladder, responsible for involuntary movement.

Muscle fibers

Elongated cells that make up muscles.

Myofilaments

Muscle equivalents of microfilaments that cause muscle contraction.

Striated

Muscles with visible banding.

Voluntary

Muscles that are subject to conscious control.

Endomysium

Delicate connective tissue sheath around a single muscle fiber.

Perimysium

Coarser fibrous membrane around a fascicle (bundle) of muscle fibers.

Epimysium

Tough "overcoat" of connective tissue that covers the entire muscle.

Tendon

Cord-like structure that attaches muscle to bone.

Aponeuroses

Sheet-like structure that attaches muscle to bone or other muscles.

Cardiac muscle

Muscle found only in the heart, responsible for involuntary contractions.

Intercalated disc

Structure that joins cardiac muscle cells together.

Function of muscles

The roles muscles play in the body, including movement, maintaining posture, stabilizing joints, generating heat, and circulating fluids.

Sarcolemma

Specialized plasma membrane of muscle cells.1. Myofibrils:Long ribbon-like organelles that fill the cytoplasm of muscle cells.

I band

Light band in a sarcomere, with a midline interruption and a darker area called Z disc.

A band

Dark band in a sarcomere, with a lighter area called H zone.

M line

Center of the H zone in a sarcomere, containing tiny protein rods that hold adjacent thick filaments together.

Sarcomere

The contractile unit of a muscle fiber, aligned end to end along the length of myofibrils.

Thick filaments

Bundled molecules of the protein myosin, extending the entire length of the dark A band.

Actin filaments

Composed of the protein actin, anchored to the Z disc in a sarcomere.

Sarcoplasmic reticulum (SR)

Specialized smooth endoplasmic reticulum in muscle cells, responsible for storing and releasing calcium.

Irritability or responsiveness

The ability of muscle fibers to receive and respond to a stimulus.

Contractility

The ability of muscle fibers to forcibly shorten when stimulated.

Extensibility

The ability of muscle fibers to stretch.

Elasticity

The ability of muscle fibers to recoil and resume their resting length after being stretched.

Motor unit

One neuron and all the skeletal muscle fibers it stimulates.

Neuromuscular junction

The association site of a nerve and muscle, where the synaptic vesicles release neurotransmitters.

Synaptic cleft

The gap between a nerve and muscle, filled with interstitial fluid.

Sliding filament theory

The theory that muscle contraction occurs when myosin heads bind to binding sites on actin filaments and slide them along, resulting in muscle shortening.

Twitch

A single, brief contraction of a muscle.

Tetanus

Sustained muscle contraction caused by repeated stimulation.

Graded responses

Different degrees of skeletal muscle shortening.

Muscle force

Depends on the number of fibers stimulated, more fibers contracting result in greater muscle tension.1. Muscle fatigue:The inability of a muscle to contract even when stimulated.

Oxygen debt

The deficit of oxygen that occurs during prolonged muscle activity when the body is unable to supply enough oxygen to the muscles.

Isotonic contractions

Contractions where the myofilaments are able to slide past each other, resulting in muscle shortening and movement.

Isometric contractions

Contractions where some muscle fibers are contracted even in a relaxed muscle, providing muscle tone.

Muscle inactivity

Leads to muscle weakness and wasting, while increased muscle use results in stronger, more efficient muscles.

Aerobic exercise

Endurance exercise that improves overall body metabolism, digestion, and neuromuscular coordination.

Resistance exercise

Isometric exercise that increases muscle size, strength, and efficiency.

Flexion

Decreasing the angle of a joint and bringing two bones closer together.

Extension

Increasing the angle or distance between two bones or parts of the body.

Rotation

Movement of a bone around its longitudinal axis.

Abduction

Moving a limb away from the midline or median plane of the body.

Adduction

Moving a limb toward the body midline.

Circumduction

Combination of flexion, extension, abduction, and adduction, commonly seen in ball-and-socket joints.

Muscle tone

The state of partial contraction in a muscle, providing stability and readiness for action.

Effects of exercise on muscle

Increased muscle size, strength, efficiency, and resistance to fatigue.1. Dorsiflexion:Lifting the foot so that its superior surface approaches the shin.

Plantar flexion

Pointing the toes away from your head.

Invert

Turning the sole of the foot medially.

Evert

Turning the sole of the foot laterally.

Supination

Turning the forearm laterally so that the palm faces anteriorly (or up) and the radius and ulna are parallel.

Pronation

Turning the forearm medially so that the palm faces posteriorly.

Opposition

The saddle joint between metacarpal 1 and carpals that allows the thumb to touch the tips of the other fingers on the same hand.

Prime mover

The muscle with the major responsibility for a certain movement.

Antagonist

The muscle that opposes or reverses a prime mover.

Synergist

The muscle that aids a prime mover in a movement and helps prevent rotation.

Fixator

The muscle that stabilizes the origin of a prime mover.

Rectus

Straight; its fibers run parallel to the imaginary line.

Oblique

The muscle fibers run obliquely (at a slant) to the imaginary line.

Relative size of the muscle

Maximus (largest), minimus (smallest), and longus (long).

Location of the muscle.

Number of origins

Triceps, biceps, and quadriceps.

Location of the muscle's origin and insertion

Muscles are named for their attachment sites.

Shape of the muscle.

Action of the muscle

Flexor, extensor, and adductor.

Circular

Fascicles arranged in concentric circles, creating a valve.

Convergent

Fascicles converge toward a single insertion tendon.

Parallel

Fascicles run parallel to the long axis of the muscle.

Pennate

Fascicles insert into the tendon from different sides.

Frontalis

Covers the frontal bone and allows you to raise your eyebrows and wrinkle your forehead.

Occipitalis

Covers the posterior aspects of the skull and pulls the scalp posteriorly.

Orbicularis oculi

Runs in circles around the eyes and allows you to close your eyes, squint, blink, and wink.

Orbicularis oris

Circular muscle of the lips that closes the mouth and protrudes the lips.

Buccinator

Runs horizontally across the cheek and inserts into the orbicularis oris, flattens the cheek.

Zygomaticus

Runs from the corner of the mouth to the cheekbone, referred to as the "smiling" muscle.

Masseter

Fan-shaped muscle overlying the temporal bone, inserts into the mandible and acts as a synergist of the masseter in closing the jaw.

Temporalis

Fan-shaped muscle overlying the temporal bone, covers the angle of the lower jaw, closes the jaw by elevating the mandible.

Platysma

Single sheet-like muscle that covers the anterolateral neck, pulls the corners of the mouth inferiorly.1. Sternocleidomastoid:Two-headed muscles found on each side of the neck that flex the neck when contracted together.

Anterior thorax muscles

Muscles that move the ribs, head, and arms.

Abdominal wall muscles

Muscles that hold the guts in and help move the vertebral column.

External intercostal

Muscles between the ribs that help raise the rib cage during inhalation.

Internal intercostal

Muscles between the ribs that depress the ribcage during forceful exhalation.

Rectus abdominis

Anterior abdominal muscle that forms a natural girdle and helps compress the abdominal contents.

External oblique

Superficial muscle of the abdomen that flexes the vertebral column and rotates the trunk.

Internal oblique

Paired superficial muscles of the abdomen that flex the vertebral column and bend it laterally.

Trapezius

Superficial muscle of the posterior neck and upper trunk that extends the head and stabilizes the scapula.

Latissimus dorsi

Two large flat muscles that cover the lower back and extend and adduct the humerus.

Erector spinae

Deep muscles of the back that span the entire length of the vertebral column and assist in back extension.

Quadratus Lumborum

Muscles that form part of the posterior abdominal wall and flex the spine laterally.

Deltoid

Triangle-shaped muscles that form the rounded shape of the shoulders and are prime movers of arm abduction.

Biceps brachii

Muscle of the arm that flexes the elbow and supinates the forearm.

Brachialis

Muscle that lies deep to the biceps brachii and is a prime mover in elbow flexion.

Brachioradialis

Muscle that arises on the humerus and inserts into the distal forearm, aiding in forearm flexion.

Triceps brachii

Muscle that extends the elbow and is the antagonist of the biceps brachii.

Gluteus maximus

Superficial muscle of the hip that extends the hip and forms most of the flesh of the buttock.

Gluteus medius

Muscle that abducts the hip and helps steady the pelvis during walking.1. Iliopsoas:Fused muscle composed of the iliacus and psoas major, responsible for hip flexion.

Adductor muscle

Muscle located on the medial side of each thigh, responsible for thigh adduction.