Human Muscular System: Muscle Actions

Vocabulary practice flashcards detailing the anatomical actions, functions, and key characteristics of muscles acting on the shoulder, arm, forearm, hand, hip, thigh, knee, leg, and foot.

Pectoralis Minor

Protraction of shoulder, as in reaching out for a door handle; rotation of scapula and depression of apex of shoulder, as in reaching down to pick up a suitcase.

Serratus Anterior

Rotation of scapula as in lifting a suitcase or raising arm above head; fixation of scapula when carrying weights in front of body; protraction of scapula; prime mover of all forward-reaching and pushing actions; nicknamed the boxer's muscle for its role in powerful thrusting movements such as a boxer's jab; holds scapula against rib cage.

Trapezius

Lateral rotation of scapula, elevating apex of shoulder as in picking up a suitcase; elevation of scapula as in shrugging shoulders; retraction of scapula as in pulling on a rope; fast, forcible depression of scapula as in hammering and swimming; fixation of scapula and shoulder during other arm movements; other roles in head and neck movement.

Levator Scapulae

Elevation of scapula; medial rotation of scapula, depressing apex of shoulder; retraction of scapula and bracing of shoulder; lateral flexion of neck.

Rhomboid Minor

Retraction of scapula and bracing of shoulder; fixation of scapula during other arm movements.

Rhomboid Major

Retraction of scapula and bracing of shoulder; fixation of scapula during other arm movements (same action as rhomboid minor).

Supraspinatus

Abduction of arm; resists downward slippage of humeral head when arm is relaxed or carrying weight.

Infraspinatus

Lateral rotation of arm; resists upward slippage of humeral head.

Teres Minor

Adduction and lateral rotation of arm; resists upward slippage of humeral head when arm is abducted.

Subscapularis

Medial rotation of arm; resists upward slippage of humeral head when arm is abducted.

Deltoid

Anterior fibers: medial rotation of arm and shoulder flexion. Lateral fibers: arm abduction. Posterior fibers: lateral rotation of arm and shoulder extension. Arm swinging in such actions as walking and bowling; adjustment of hand height for manual tasks.

Teres Major

Medial rotation of arm; shoulder extension; arm swinging during walking.

Coracobrachialis

Medial rotation of humerus; shoulder flexion; resists deviation of arm from frontal plane during abduction.

Pectoralis Major

Medial rotation and adduction of arm; shoulder flexion, as in climbing or hugging; assistance in deep breathing.

Latissimus Dorsi

Medial rotation and adduction of arm; shoulder extension, as in pulling on oars of a rowboat; backswing of arm as in walking or bowling; strong downstrokes of arm as in hammering and swimming (nicknamed the swimmer's muscle); assistance in deep inhalation, sudden exhalation as in sneezing and coughing, and prolonged forceful exhalation as in singing or playing a wind instrument; pulls body forward and upward when hands grasp overhead objects, as in climbing.

Brachialis

Prime mover of elbow flexion.

Biceps Brachii

Elbow flexion; rapid or forceful supination of forearm; slight shoulder flexion; long head stabilizes shoulder by holding humeral head against glenoid cavity.

Triceps Brachii

Elbow extension; long head extends and adducts arm.

Brachioradialis

Elbow flexion.

Anconeus

Elbow extension.

Pronator Quadratus

Forearm pronation; resists separation of radius and ulna when force is applied to forearm through wrist, as in doing push-ups.

Pronator Teres

Forearm pronation in rapid or forceful actions.

Supinator

Forearm supination, as in turning a doorknob or driving a screw into wood with the right hand.

Flexor Carpi Radialis

Anterior and radial flexion of wrist.

Flexor Carpi Ulnaris

Anterior and ulnar flexion of wrist.

Flexor Digitorum Superficialis

Wrist, metacarpophalangeal, and interphalangeal joint flexion.

Palmaris Longus

Wrist flexion; anchorage of palmar skin and fascia; resistance to shearing forces when stress is applied by tool use, climbing, and other actions.

Flexor Digitorum Profundus

Wrist, metacarpophalangeal, and interphalangeal joint flexion; sole flexor of distal interphalangeal joints.

Flexor Pollicis Longus

Thumb flexion.

Extensor Carpi Radialis Longus

Extension and radial flexion of wrist.

Extensor Carpi Radialis Brevis

Extension and radial flexion of wrist.

Extensor Digitorum

Wrist, metacarpophalangeal, and interphalangeal joint extension; tends to spread (abduct) fingers away from each other.

Extensor Digiti Minimi

Wrist and little finger extension.

Extensor Carpi Ulnaris

Wrist extension and ulnar flexion; wrist fixation when fist is clenched or hand grips an object.

Abductor Pollicis Longus

Radial abduction of thumb; extension of carpometacarpal joint of thumb.

Extensor Pollicis Brevis

Extension of thumb at carpometacarpal and metacarpophalangeal joints.

Extensor Pollicis Longus

Extension of thumb at carpometacarpal and metacarpophalangeal joints of thumb; adduction and lateral rotation of thumb.

Adductor Pollicis

Thumb adduction as in gripping a tool.

Abductor Pollicis Brevis

Thumb abduction.

Flexor Pollicis Brevis

Thumb flexion at metacarpophalangeal joint.

Abductor Digiti Minimi

Abduction of little finger, as in spreading fingers apart.

Flexor Digiti Minimi Brevis

Flexion of little finger at metacarpophalangeal joint.

Iliacus

Hip flexion when trunk is fixed, as in stair climbing; waist flexion when thigh is fixed, as in bending forward in a chair or sitting up in bed; balances trunk during sitting.

Psoas Major

Hip flexion when trunk is fixed, as in stair climbing; waist flexion when thigh is fixed, as in bending forward in a chair or sitting up in bed; balances trunk during sitting (same action as iliacus).

Tensor Fasciae Latae

Knee extension; lateral rotation of tibia; abduction and medial rotation of femur; during standing, steadies pelvis on femoral head and femoral condyles on tibial plateau.

Gluteus Maximus

Hip extension, as in stair climbing; backswing of thigh during running and walking; thigh abduction; elevates trunk when rising from stooped or kneeling position; extends waist after bending forward; prevents trunk from pitching forward during walking and running; stabilizes femur on tibia.

Gluteus Medius and Gluteus Minimus

Abduction and medial rotation of thigh; during walking, shifts weight of trunk toward limb with foot on the ground as other foot is lifted.

Adductor Brevis

Thigh adduction.

Adductor Longus

Thigh adduction and medial rotation; hip flexion.

Adductor Magnus

Thigh adduction and medial rotation; hip extension.

Gracilis

Thigh adduction; knee flexion; medial rotation of tibia.

Pectineus

Thigh adduction; hip flexion.

Piriformis

Lateral rotation of extended thigh and abduction of flexed thigh.

Quadratus Femoris

Lateral rotation of thigh.

Quadriceps Femoris

Knee extension, as in kicking a ball or rising from a chair.

Rectus Femoris

Knee extension, as in kicking a ball or rising from a chair; hip flexion.

Vastus Lateralis

Knee extension; retention of patella on patellar surface of femur during knee movements.

Vastus Medialis

Knee extension; retention of patella on patellar surface of femur during knee movements (same action as vastus lateralis).

Vastus Intermedius

Knee extension.

Sartorius

Knee and hip flexion, as in sitting or climbing; thigh abduction and lateral rotation.

Biceps Femoris

Knee flexion; hip extension; lateral rotation of tibia on femur when knee is flexed; lateral rotation of femur when hip is extended; elevates trunk when rising from stooped or kneeling position; counteracts forward bending at hips.

Semitendinosus

Knee flexion; medial rotation of tibia on femur when knee is flexed; medial rotation of femur when hip is extended; counteracts forward bending at hips.

Semimembranosus

Knee flexion; medial rotation of tibia on femur when knee is flexed; medial rotation of femur when hip is extended; counteracts forward bending at hips (same action as semitendinosus).

Popliteus

Medial rotation of tibia on femur, or lateral rotation of femur if tibia is fixed, to unlock knee when joint is extended and allow knee flexion.

Fibularis (Peroneus) Tertius

Foot dorsiflexion and eversion; helps toes clear the ground during forward swing of leg in walking.

Extensor Digitorum Longus

Foot dorsiflexion; toe extension; tautens plantar aponeurosis.

Extensor Hallucis Longus

Foot dorsiflexion; great toe extension.

Tibialis Anterior

Foot dorsiflexion and inversion; resists backward tipping of body, as when standing on a moving boat deck; supports medial longitudinal arch of foot.

Gastrocnemius

Foot plantar flexion; knee flexion; important in walking, running, and jumping.

Soleus

Foot plantar flexion; stabilizes leg on ankle when rising to standing position.

Flexor Digitorum Longus

Flexion of interphalangeal joints of digits II–V as foot is raised from ground; stabilizes metatarsal heads and maintains ground contact of distal segments of toes during toe-off and tiptoeing.

Flexor Hallucis Longus

Flexion of interphalangeal joint of great toe as foot is raised from ground; stabilizes metatarsal head and maintains ground contact of distal segment of great toe during toe-off and tiptoeing.

Tibialis Posterior

Foot inversion; controls foot pronation and plantar flexion in walking.

Fibularis (Peroneus) Brevis

Limits foot inversion; steadies leg on foot; maintains concavity of sole during toe-off and tiptoeing.

Fibularis (Peroneus) Longus

Plantar flexion; foot eversion; maintains concavity of sole during toe-off and tiptoeing.