Muscles of the Human Body

Flashcards covering the origin, insertion, and action of major muscles.

Gastrocnemius

Origin: Medial and lateral condyles of the femur; Insertion: Calcaneus via Achilles tendon; Action: Plantarflexes foot; flexes knee

Rectus Femoris

Origin: Anterior inferior iliac spine; Insertion: Tibial tuberosity via patellar ligament; Action: Extends knee; flexes hip

Vastus Lateralis

Origin: Greater trochanter and linea aspera of femur; Insertion: Tibial tuberosity; Action: Extends knee

Vastus Intermedius

Origin: Anterior and lateral femur; Insertion: Tibial tuberosity; Action: Extends knee

Vastus Medialis

Origin: Linea aspera of femur; Insertion: Tibial tuberosity; Action: Extends knee

Gluteus Maximus

Origin: Ilium, sacrum, coccyx; Insertion: Gluteal tuberosity of femur, iliotibial tract; Action: Extends, laterally rotates thigh

Gluteus Medius

Origin: Lateral ilium; Insertion: Greater trochanter of femur; Action: Abducts and medially rotates thigh

Gluteus Minimus

Origin: Lateral ilium; Insertion: Greater trochanter of femur; Action: Abducts and medially rotates thigh

Biceps Femoris

Origin: Ischial tuberosity (long head), femur (short head); Insertion: Head of fibula; Action: Flexes knee; extends thigh

Semitendinosus

Origin: Ischial tuberosity; Insertion: Medial tibia; Action: Flexes knee; extends thigh

Semimembranosus

Origin: Ischial tuberosity; Insertion: Medial condyle of tibia; Action: Flexes knee; extends thigh

Rectus Abdominis

Origin: Pubic crest and symphysis; Insertion: Xiphoid process, ribs 5–7; Action: Flexes trunk; compresses abdomen

External Oblique

Origin: Ribs 5–12; Insertion: Iliac crest, linea alba; Action: Flexes trunk; rotates to opposite side; compresses abdomen

Internal Oblique

Origin: Iliac crest, inguinal ligament; Insertion: Ribs 10–12, linea alba; Action: Flexes trunk; rotates to same side; compresses abdomen

Transversus Abdominis

Origin: Iliac crest, ribs 7–12, thoracolumbar fascia; Insertion: Linea alba, pubis; Action: Compresses abdominal contents

Psoas Major

Origin: T12–L5 vertebrae; Insertion: Lesser trochanter of femur; Action: Flexes thigh and trunk

Pectoralis Major

Origin: Clavicle, sternum, ribs 1–6; Insertion: Greater tubercle of humerus; Action: Adducts, flexes, and medially rotates arm

Serratus Anterior

Origin: Ribs 1–8; Insertion: Medial border of scapula; Action: Protracts and upwardly rotates scapula

Latissimus Dorsi

Origin: T7–T12, iliac crest, ribs 9–12; Insertion: Intertubercular groove of humerus; Action: Extends, adducts, and medially rotates arm

Rhomboid Major

Origin: Spinous processes T2–T5; Insertion: Medial border of scapula; Action: Retracts and downwardly rotates scapula

Trapezius

Origin: Occipital bone, C7–T12; Insertion: Clavicle, acromion, spine of scapula; Action: Elevates, retracts, depresses, and rotates scapula

Erector Spinae (Spinalis, Longissimus, Iliocostalis)

Origin: Iliac crest, sacrum, lumbar vertebrae spinous processes; Insertion: Ribs, cervical/thoracic vertebrae, skull; Action: Extends and laterally flexes spine; maintains posture

Biceps Brachii

Origin: Supraglenoid tubercle & coracoid process of scapula; Insertion: Radial tuberosity; Action: Flexes elbow; supinates forearm

Triceps Brachii

Origin: Infraglenoid tubercle (long head), posterior humerus (lateral & medial heads); Insertion: Olecranon of ulna; Action: Extends elbow; assists in shoulder extension

Deltoid

Origin: Clavicle, acromion, and spine of scapula; Insertion: Deltoid tuberosity of humerus; Action: Abducts arm (middle); flexes & medially rotates (anterior); extends & laterally rotates (posterior)