Muscle Anatomy & Functions Cheat Sheet | Origins, Insertions & Actions|Verified Questions Provided with A+ Graded Rationales Latest Updated 2026

Muscle Anatomy & Functions Cheat Sheet | Origins, Insertions & Actions|Verified Questions Provided with A+ Graded Rationales Latest Updated 2026 Temporalis Origin: Along temporal lines of skull; Insertion: Coronoid process of mandible; Action: Elevates mandible. Masseter Origin: Zygomatic arch; Insertion: Mandibular ramus; Action: Elevates mandible and closes the jaws. Sternocleidomastoid Origin: Two bellies: clavicular head attaches to sternal end of clavicle; sternal head attaches to manubrium; Action: Together, they flex the neck; Alone they perform ipsilateral flexion and neck contralateral rotation to the opposite side. Pectoralis Major Origin: Cartilages of ribs 2-6, sternum and clavicle; Insertion: Greater tubercle and intertubercular sulcus of humerus; Action: Flexion, adduction, and medial rotation at shoulder. Pectoralis Minor Origin: Surfaces of ribs 2-5; Insertion: Coracoid process of scapula; Action: Depresses and protracts shoulder; rotates scapula so glenoid cavity moves inferiorly; elevates ribs if scapula is stationary. Biceps Brachii Origin: Short Head: from the coracoid process; Long Head: supraglenoid tubercle (Both on the scapula); Insertion: Radial tuberosity; Action: Flexion at elbow and shoulder; supination. Brachioradialis Origin: Ridge superior to the lateral epicondyle of humerus; Insertion: Lateral aspect of styloid process of radius; Action: Three B's Bend the Elbow. Flexor Carpi Ulnaris Origin: Medial epicondyle of humerus; Insertion: Pisiform, hamate, and base of fifth metacarpal bone; Action: Flexion and abduction at wrist. Flexor Carpi Radialis Origin: Medial epicondyle of humerus; Insertion: Bases of second and third metacarpal bones; Action: Flexion and adduction at wrist. Rectus Abdominus Origin: Surface of pubis around symphysis; Insertion: Costal cartilages (ribs 5-7) and xiphoid process; Action: Depresses ribs, flexes vertebral column, compresses abdomen. Iliopsoas Group Psoas Major: Origin: Transverse processes of vertebrae (T12-L5); Action: Flexion at hip. Iliacus: Origin: Iliac fossa of ilium; Insertion: Tendon fused with that of psoas major. Adductor Longus Origin: Inferior ramus of pubis; Insertion: Linea aspera of femur; Action: Adduction, flexion, and medial rotation at hip. Sartorius Origin: Anterior superior iliac spine; Insertion: Medial surface of tibia (Pes Anserinus); Action: Flexion at knee; flexion and lateral rotation at hip. Rectus Femoris Origin: Anterior inferior iliac spine; Insertion: Quadriceps Tendon; Action: Extension at Knee. Tibialis Anterior Origin: Lateral condyle of Tibia; Insertion: First metatarsal bone and medial cuneiform bone; Action: Flexion (dorsiflexion) at ankle; inversion of foot. Extensor hallucis longus Origin: Surface of Fibula; Insertion: Distal phalanx of great toe; Action: Extension at joints of great toe. Extensor digitorum longus Origin: Not specified; Insertion: Not specified; Action: Not specified. Extensor digitorum longus Lateral condyle of tibia and surface of fibula; Phalanges 2-5; Extension at joints of toes 2-5. Trapezius Clavicle, acromion of scapula and scapular spine; Occipital bone, ligamentum nuchae, and spinous processes of thoracic vertebrae; (1) elevate, retract, depress, or rotate scapula upward, (2) elevate clavicle, or (3) extend neck. Supraspinatus Supraspinous fossa of scapula; Greater tubercle of humerus; Abduction at the shoulder. Infraspinatus Infraspinous fossa of scapula; Lateral rotation at shoulder. Teres Minor Lateral border of scapula; Medial rotation at shoulder. Subscapular Subscapular fossa of scapula; Lesser tubercle of humerus; Medial rotation at shoulder. Rhomboid Major Spinous processes of superior thoracic vertebrae; Medial border of scapula from spine to inferior angle; Adducts scapula and performs downward rotation. Latissimus dorsi Intertubercular sulcus of the humerus; Spinous processes of inferior thoracic and all lumbar vertebrae, ribs 8-12, a