What are the two main divisions of the muscular system?
Axial muscles support and position the axial skeleton; Appendicular muscles support, move, and brace the limbs.
Define origin and insertion in muscle attachment.
Origin is the fixed attachment point of a muscle; Insertion is the movable attachment point, typically distal to the origin.
What is the role of tendons in the muscular system?
Tendons connect muscles to bones and conduct the forces of muscle contraction to perform specific movements.
Describe the functional roles of agonist, antagonist, and synergist muscles.
Agonist produces the primary movement; Antagonist opposes the agonist; Synergist assists the agonist to work efficiently.
How does muscle naming provide clues about muscle location and function?
Muscle names can indicate body region, relative position, direction, size, shape, number of origins, or action.
What is a fascicle in muscle anatomy?
A fascicle is a bundle of muscle fibers (cells) within a muscle.
Compare parallel, convergent, and pennate muscle fascicle arrangements.
Parallel: fascicles run along the muscle's long axis; Convergent: fascicles converge on a common attachment; Pennate: fascicles attach at an angle to a tendon.
What type of muscle fascicle arrangement produces the strongest contractions?
Pennate muscles produce the strongest contractions due to their angled fascicle arrangement.
What is the function of circular (sphincter) muscles?
Circular muscles surround openings and contract to open or close body openings.
What are the four groups of axial muscles?
Muscles of head & neck, muscles of facial expression, muscles of vertebral column, and muscles of anterior thoracic & abdominal trunk.
What is the primary function of appendicular muscles?
Appendicular muscles stabilize and move the appendicular skeleton, including limbs and girdles.
Name the muscles of facial expression and their general function.
Muscles like orbicularis oculi, zygomaticus major, and orbicularis oris move skin to allow facial expressions.
What are the muscles of mastication and their action?
Masseter and temporalis muscles elevate the mandible to enable chewing.
Describe the action and attachments of the sternocleidomastoid muscle.
Flexes neck and rotates head toward shoulder; origin at sternum and clavicle, insertion at mastoid process.
What muscles assist in breathing by moving the rib cage?
External intercostals elevate ribs for inhalation; internal intercostals depress ribs for exhalation; diaphragm expands thoracic cavity.
List the muscles forming the anterior abdominal wall and their functions.
Rectus abdominis flexes spine; external and internal obliques flex and rotate spine; transversus abdominis compresses abdomen.
What muscles position the shoulder and move the arm?
Trapezius elevates and retracts shoulder; deltoid abducts shoulder; pectoralis major flexes and adducts arm; latissimus dorsi extends and adducts arm.
What is the rotator cuff group and its function?
Four muscles (supraspinatus, infraspinatus, teres minor, subscapularis) that stabilize the shoulder joint.
Name the primary muscles that move the forearm at the elbow.
Biceps brachii, brachialis, and brachioradialis flex the forearm; triceps brachii extends the forearm.
Which muscles move the thigh and leg, and what are their actions?
Iliopsoas flexes hip; gluteus maximus extends and laterally rotates hip; quadriceps femoris extends knee; hamstrings flex knee and extend hip.
What muscles move the foot and toes?
Tibialis anterior dorsiflexes and inverts foot; gastrocnemius plantar flexes and inverts foot; extensor digitorum longus extends toes.