GENERAL BIOLOGY 2 MUSCULAR SYSTEM

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Muscular System

Body system of muscles and tendons responsible for movement, posture, and assisting blood circulation and other vital functions.

Tendon

Strong connective tissue that attaches muscle to bone.

Movement (muscle function)

Action in which muscles contract and relax to move bones and joints.

Posture Maintenance

Muscular activity that keeps the body upright and stable.

Thermogenesis

Heat production generated by muscle contractions.

Electrical Excitability

Ability of muscle tissue to respond to stimuli by generating electrical signals.

Contractility

Ability of muscle fibers to shorten forcefully when stimulated.

Extensibility

Capacity of muscle to be stretched without damage.

Elasticity

Ability of muscle to return to its original length and shape after contraction or extension.

Voluntary Muscle

Muscle whose contractions are under conscious control.

Involuntary Muscle

Muscle whose contractions occur without conscious control.

Skeletal Muscle

Striated, long-fibered, multinucleate voluntary muscle attached to bones; produces body movement and heat.

Cardiac Muscle

Striated, branched, single-nucleus involuntary muscle found only in the heart; pumps blood.

Smooth Muscle

Non-striated, spindle-shaped involuntary muscle in walls of organs and vessels; moves substances through the body.

Somatic Nervous System

Division of the nervous system that voluntarily controls skeletal muscles.

Autonomic Nervous System

Division of the nervous system that involuntarily controls cardiac and smooth muscles.

Flexor

Muscle whose principal action bends a limb.

Extensor

Muscle whose principal action straightens a limb.

Abductor

Muscle that moves a bone away from the body’s midline.

Adductor

Muscle that moves a bone toward the body’s midline.

Levator

Muscle that raises or elevates a body part.

Depressor

Muscle that lowers or depresses a body part.

Supinator

Muscle that turns the palm superiorly or anteriorly.

Pronator

Muscle that turns the palm inferiorly or posteriorly.

Sphincter

Circular muscle that decreases the size of an opening.

Tensor

Muscle that makes a body part rigid.

Rotator

Muscle that rotates a bone around its axis.

Biceps

Muscle with two origins (heads).

Triceps

Muscle with three origins (heads).

Quadriceps

Muscle group with four origins (heads).

Deltoid

Triangular-shaped shoulder muscle; name reflects its shape.

Trapezius

Trapezoid-shaped muscle of upper back and neck.

Rhomboid

Diamond-shaped muscle connecting scapula to spine.

Platysma

Flat, superficial neck muscle that pulls the mouth’s corners downward.

Piriformis

Pear-shaped deep hip muscle.

Serratus

Saw-toothed muscle with serrated appearance

Gracilis

Slender, medial thigh muscle that adducts the hip.

Frontalis

Forehead muscle that raises eyebrows and wrinkles forehead. It is located in the frontal region of the skull and is involved in facial expressions.

Orbicularis Oris

Circular lip muscle that closes and protrudes the lips; the “kissing” muscle.

Buccinator

Cheek muscle that flattens cheeks during whistling or blowing. It helps in holding food between the teeth during chewing.

Zygomaticus

Muscle that raises mouth corners; called the “smiling muscle.”

Masseter

Jaw-closing muscle that elevates the mandible. It is one of the strongest muscles in the body, crucial for chewing.

Temporalis

Fan-shaped chewing muscle covering the temporal bone.

Sternocleidomastoid

Two-headed neck muscle that flexes the neck; known as the “prayer muscle.”

Rectus Abdominis

Long vertical abdominal muscle—the “six-pack”—important for trunk flexion. It plays a key role in maintaining posture and stability of the torso.

Transversus Abdominis

Deepest abdominal muscle that wraps around the torso to stabilize the core.

Biceps Brachii

Prominent two-headed arm muscle; prime mover for forearm flexion (IN RED).

Triceps Brachii

Only muscle on posterior humerus; extends forearm and known as the “boxer’s muscle.”

Gluteus Maximus

Large superficial hip muscle that extends the thigh; forms bulk of buttocks.

Pectoralis Major

Large chest muscle that adducts and flexes the humerus across the chest.

Pectoralis Minor

Smaller deep chest muscle that pulls the shoulder area forward.

Gastrocnemius

Two-belly calf muscle; plantar-flexes foot; called the “toe-dancer’s muscle.”

Sartorius

Long superficial thigh muscle; enables cross-legged position; called the “tailor’s muscle.”

Orbicularis Oculi

A circular muscle around the eye that enables blinking and closing of the eyelids.