Muscle origins, insertions, actions

Gluteus Maximus

O: Posterior surface of ilium and sacrum and coccyx I: Iliotibial tract (IT band), gluteal tuberosity of femur A: Extends, laterally rotates, and abducts thigh at hip

Gluteus minimus

O: outer surface of ilium I: anterior greater trochanter A: hip abduction and hip IR

vastus intermedius

Origin: Anterior and lateral surface of femur Insertion: tibial tuberosity of patellar Action: Extension of leg at knee joint

Rectus femoris

Origin: Anterior inferior iliac spine Insertion: Patella and Tibia Action: Extension of leg at knee joint and

biceps femoris (hamstrings, 1 of 3)

Origin: Ischial tuberosity, linea aspera Insertion: fibula and tibia Action: Flexes leg at knee and extends thigh at hip

Gastrocnemius

Origin: Lateral and medial condyles of femur Insetion: Calcaneus via achilles tendon Action: knee flexion, plantar flexion

vastus medialis

Origin: Linea aspera of femur Insertion: tibial tuberosity via patellar ligament Action: Extension of leg at knee joint

Biceps brachii

Origin: Long head tubercle above glenoid cavity of scapula; short head supraglenoid cavity Insertion: Radial tuberosity of radius Action: Flexes and supinates forearm (palm up) Mneumonic: you walk Longer on a street Corner. You walk Shorter on a Superhighway

Gluteus medius

Origin: Outer surface of ilium inferior to tliac crest Insertion: lat. surface of greater trochanter Action: abducts and medially rotates thigh

Tibialis anterior

Origin: Tibia and interosseous membrane Insertion: metatarsals Action: Dorsiflexion and inverts foot

Deltoid (anterior lateral and posterior)

Origin: clavicle (anterior), acromion (lateral), scapula (posterior) Insertion: Deltoid tuberosity of humerus Action: anterior raises/rotates arm forward; Lateral abducts arm; posterior raises/rotatesarm backward Deltoid helps you carry SACS (spine of scapula, acromium, clavicle

Vastus lateralis

Origin: greater trochanter of femur Insertion: tibial tuberosity of patellar Action: extends leg at knee

Semitendonosus (hamstrings, 1 of 3)

Origin: ischial tuberosity Insertion: medial aspect of upper tibial shaft Action: extends thigh at hip; flexes knee

semimembranosus (hamstrings, 1 of 3)

Origin: ischial tuberosity Insertion: posteromedial condyle of tibial shaft Action: extends thigh at hip; flexes knee

Triceps brachii (lateral medial and long head)

Origin: long head in glenoid; medial and lateral at humerus Insertion: olecranon process of ulna Action: extends forearm and stabilizes shoulder