Human Muscle Anatomy: Origins, Insertions, and Actions

Upper Body Muscles

Trapezius

• Origin: Occipital bone and thoracic spinous processes
• Insertion: Clavicle and scapula
• Action: Rotate scapula, elevate clavicle, extend neck

Triceps Brachii

• Origin: Superior and posterior humerus and scapula
• Insertion: Olecranon of ulna
• Action: Extension at elbow and shoulder, plus shoulder adduction

Extensor Carpi Radialis Longus

• Origin: Lateral supracondylar ridge of humerus
• Insertion: Second metacarpal bone
• Action: Extension and abduction at wrist

Extensor Carpi Ulnaris

• Origin: Lateral epicondyle of humerus
• Insertion: Fifth metacarpal bone
• Action: Extension and adduction at wrist

Rotator Cuff and Back Muscles

Subscapularis

• Origin: Subscapular fossa of scapula
• Insertion: Lesser tubercle of humerus
• Action: Medial rotation at shoulder

Supraspinatus

• Origin: Supraspinous fossa of scapula
• Insertion: Greater tubercle of humerus
• Action: Abduction at shoulder

Infraspinatus

• Origin: Infraspinous fossa of scapula
• Insertion: Greater tubercle of humerus
• Action: Lateral rotation at shoulder

Teres Minor

• Origin: Lateral border of scapula
• Insertion: Greater tubercle of humerus
• Action: Lateral rotation at shoulder

Rhomboid Major

• Origin: Superior thoracic spinous processes
• Insertion: Medial border of scapula from spine to inferior angle
• Action: Adduction of scapula and downward rotation

Latissimus Dorsi

• Origin: Ribs 8-12, inferior thoracic and all lumbar spinous processes
• Insertion: Intertubercular groove of humerus
• Action: Extension, adduction, and medial rotation at shoulder

Lower Body Muscles

Gluteus Maximus

• Origin: Iliac crest and lateral surface of ilium
• Insertion: Iliotibial tract and gluteal tuberosity of femur
• Action: Extension and lateral rotation at hip

Gluteus Medius

• Origin: Anterior iliac crest of ilium
• Insertion: Greater trochanter of femur
• Action: Abduction and medial rotation at hip

Biceps Femoris

• Origin: Ischial tuberosity and linea aspera of femur
• Insertion: Head of fibula and lateral condyle of tibia
• Action: Flexion at knee, extension and lateral rotation at hip

Semitendinosus

• Origin: Ischial tuberosity
• Insertion: Proximal and medial surface of tibia
• Action: Flexion at knee, extension and medial rotation at hip

Semimembranosus

• Origin: Ischial tuberosity
• Insertion: Posterior medial condyle of tibia
• Action: Flexion at knee, extension and medial rotation at hip

Gastrocnemius

• Origin: Femoral condyles
• Insertion: Calcaneus
• Action: Plantar flexion, inversion of foot, flexion at knee

Soleus

• Origin: Head of fibula and posteromedial shaft of tibia
• Insertion: Calcaneus
• Action: Plantar flexion