Muscular System Lecture Notes SET 1

A set of vocabulary flashcards covering the principles of the muscular system, lever classes, naming conventions, and specific facial and trunk muscles.

Skeletal Muscular System Size

The system is composed of roughly $700$ muscles, of which students must identify $47$.

Muscle Action Principle

Muscles only pull; they do not push.

Prime Mover (Agonist)

The muscle that has the major responsibility for a particular movement.

Antagonist

A muscle that opposes or reverses a specific movement.

Synergist

A muscle that helps the prime mover by adding extra power and reducing undesirable or unnecessary movements.

Fixator

A subtype of synergist that immobilizes a bone or a muscle's origin to provide a stable base for movement.

Origin

The site of muscle attachment that is usually stationary during contraction.

Insertion

The site of muscle attachment that usually moves during contraction.

Lever

A rigid structure that moves around a fixed point called a fulcrum.

Fulcrum

The fixed pivot point of a lever; in the human body, joints act as fulcrums.

Effort

The force applied to cause movement in a lever system.

Load

The force that resists movement in a lever system.

First Class Lever

An arrangement where the fulcrum is positioned between the load and the effort, such as the occipital condyle.

Second Class Lever

An arrangement where the load is located between the fulcrum and the effort, such as the gastrocnemius acting on the foot.

Third Class Lever

An arrangement where the effort is applied between the fulcrum and the load, such as the biceps brachii at the elbow.

Speed Levers

Levers where force is lost but speed and range of movement are gained.

Power Levers

Levers that are slower and more stable, prioritizing strength over speed.

Pennant Arrangement

A fascicle pattern where short fascicles attach obliquely to a central tendon; can be unipennant, bipennant, or multipennant.

Rectus

A naming term indicating muscle fibers run straight or parallel to the midline.

Transversus

A naming term indicating muscle fibers run at right angles to the midline.

Oblique

A naming term indicating muscle fibers run at angles to an imaginary fixed axis.

Serratus

A muscle shape description meaning 'sawtooth'.

Orbicular

A muscle shape description meaning 'circular'.

Gracilis

A muscle shape description meaning 'slender'.

Occipital frontalis

Muscle originating at the epicranial aponeurosis and inserting into the supraorbital skin; responsible for wrinkling the forehead.

Orbicularis oris

Muscle around the mouth used for closing the mouth and kissing.

Zygomaticus major

Muscle originating on the zygomatic bone and inserting into the corner of the mouth; used for smiling.

Orbicularis oculi

Muscle that circles the eye and functions to close the eyes.

Masseter

Muscle originating on the zygomatic arch and inserting into the lateral surface of the mandible; elevates the mandible.

Temporalis

Synergistic muscle that works with the masseter to elevate the mandible.

Sternocleidomastoid

Muscle originating at the sternum and clavicle and inserting into the mastoid process; rotates the head or pulls it downward.

Rectus abdominis

Muscle originating at the pubic crest and symphysis; compresses the abdomen and flexes the vertebral column.

External oblique

Muscle originating at ribs $5$ through $12$; functions to compress the abdomen and rotate the body.