Muscular System Anatomy

Vocabulary flashcards covering human muscular anatomy, including respiration, abdominal wall, pelvic floor, pectoral girdle, upper limb, lower limb, and clinical considerations.

Serratus posterior superior

A posterior thoracic muscle that elevates ribs during forced inspiration and increases lateral dimensions of the thorax.

Serratus posterior inferior

A posterior thoracic muscle that depresses ribs during forced expiration.

Scalene muscles

Muscles that help elevate the first and second ribs during forced inspiration.

External intercostals

Muscles that elevate the ribs during inspiration, expanding the thoracic cavity.

Internal intercostals

Muscles deep to external intercostals with fibers at right angles to them that depress ribs during forced expiration.

Transversus thoracis

A muscle that depresses ribs during forced expiration.

Diaphragm

An internally placed dome-shaped muscle partitioning the thoracic and abdominal cavities; the most important muscle associated with breathing.

External oblique

Superficial abdominal muscle with inferomedially directed fibers that forms an aponeurosis anteriorly becoming the inguinal ligament inferiorly.

Internal oblique

Abdominal muscle located deep to the external oblique with superomedially projecting fibers.

Transversus abdominis

The deepest abdominal muscle, with fibers projecting transversely.

Rectus abdominis

Anteromedial abdominal muscle running vertically, partitioned into four segments by tendinous intersections and enclosed in the rectus sheath.

Linea alba

A fibrous strip connecting the rectus sheaths of the two sides of the abdominal wall.

Pelvic diaphragm

A collective structure formed by three layers of muscles and fasciae that forms the floor of the pelvic cavity and supports pelvic viscera.

Perineum

A diamond-shaped region between the lower appendages bounded by the pubic symphysis, coccyx, and ischial tuberosities, divided into the urogenital triangle and anal triangle.

Pectoralis minor

An anterior thoracic muscle deep to the pectoralis major that helps depress and protract the scapula.

Serratus anterior

A fan-shaped muscle between the ribs and scapula that protracts and stabilizes the scapula, and acts as a superior rotator.

Subclavius

An anterior thoracic muscle extending from the clavicle to the first rib that stabilizes and depresses the scapula.

Levator scapulae

A posterior thoracic muscle attaching to cervical vertebrae and scapula that elevates and inferiorly rotates the scapula.

Rhomboid major and minor

Posterior thoracic muscles running inferolaterally from vertebrae to scapula deep to the trapezius that elevate, retract, and inferiorly rotate the scapula.

Trapezius

A diamond-shaped muscle extending from the skull and vertebral column to the pectoral girdle that elevates, depresses, retracts, or rotates the scapula.

Latissimus dorsi

A broad triangular muscle on the back that acts as a prime arm extensor, as well as adducting and medially rotating the arm.

Pectoralis major

A thick, fan-shaped muscle on the superior anterior thorax that is the prime arm flexor, adducting and medially rotating the arm.

Deltoid

The prime abductor of the arm; anterior fibers flex and medially rotate, lateral fibers abduct, and posterior fibers extend and laterally rotate the arm.

Coracobrachialis

A muscle that flexes and adducts the arm.

Teres major

A muscle that extends, adducts, and medially rotates the arm.

Subscapularis

A rotator cuff muscle that medially rotates the arm and helps in the wind up for a pitch.

Supraspinatus

A rotator cuff muscle that abducts the arm and helps execute pitch delivery.

Infraspinatus and teres minor

Rotator cuff muscles that adduct and laterally rotate the arm, working to slow the arm at the end of a pitch.

Brachialis

A muscle deep to the biceps brachii that serves as the most powerful flexor of the forearm.

Brachioradialis

A muscle located on the anterolateral forearm that acts as a synergist in elbow flexion.

Anconeus

A weak elbow extensor crossing the posterolateral region of the elbow.

Pronator teres and pronator quadratus

Forearm muscles in the anterior compartment that rotate the radius across the ulna to pronate the forearm.

Supinator

A muscle in the posterior compartment of the forearm that supinates the forearm.

Flexor retinaculum

A fibrous band on the palmar surface of carpal bones that forms the tight space known as the carpal tunnel.

Flexor digitorum superficialis

The single muscle of the intermediate layer of the anterior forearm compartment; flexes the wrist, MP, and PIP joints of fingers 2–5.

Flexor digitorum profundus

A deep anterior forearm muscle whose tendons insert on distal phalanges of fingers 2–5 to flex the wrist, MP, PIP, and DIP joints.

Extensor digitorum

A superficial posterior forearm muscle inserting on distal phalanges of fingers 2–5 to extend the wrist, MP, PIP, and DIP joints.

Thenar group

A fleshy mass of intrinsic hand muscles at the base of the thumb comprising flexor pollicis brevis, abductor pollicis brevis, and opponens pollicis.

Hypothenar group

A fleshy mass of intrinsic hand muscles at the base of the little finger comprising flexor digiti minimi brevis, abductor digiti minimi, and opponens digiti minimi.

Lumbricals (Hand)

Worm-shaped midpalmar intrinsic muscles that flex MP joints and extend PIP and DIP joints of fingers 2–5.

Dorsal interossei (Hand)

Midpalmar muscles located between metacarpals that abduct fingers 2–5, flex MP joints, and extend PIP and DIP joints.

Palmar interossei (Hand)

Midpalmar muscles located between metacarpals that adduct fingers, flex MP joints, and extend PIP and DIP joints of fingers 2–5.

Iliopsoas

A collective term for psoas major and iliacus muscles running from lumbar vertebrae and ilium to femur that flex the thigh.

Tensor fasciae latae

A lateral thigh muscle attaching to the iliotibial tract that abducts and medially rotates the thigh.

Gluteus maximus

The chief extensor of the thigh, which also laterally rotates the thigh.

Hamstrings

A posterior thigh muscle group consisting of biceps femoris, semimembranosus, and semitendinosus that extends the thigh and flexes the knee.

Quadriceps femoris

A composite anterior thigh muscle with four heads (rectus femoris, vastus lateralis, vastus medialis, vastus intermedius) that serves as the prime mover of knee extension.

Sartorius

An anterior thigh muscle that flexes and laterally rotates the thigh, as well as flexing and medially rotating the leg.

Tibialis anterior

The primary dorsiflexor of the foot located in the anterior leg compartment, which also inverts the foot.

Triceps surae

A composite muscle formed by the gastrocnemius and soleus that inserts at the heel via the calcaneal tendon.

Popliteus

A deep posterior leg muscle that flexes the leg and medially rotates the tibia with no action at the ankle or foot.

Compartment syndrome

Compression of blood vessels within a limb compartment caused by inflammation and swelling secondary to strain or trauma due to unyielding deep fascia.