Skeletal muscles

• • masseter: elevates mandible as in closing jaw.
  • origin: zygomatic arch
  • Insertion: Lateral surface of mandible
• Sternocleidomastoid: Both muscle together flex neck;acting alone rotates head towards shoulder on opposite side of body

  Origin: Manubrium of sternum & medial portion of clavicle

  Insertion: Mastoid process of temporal bone
• Pectoralis: flexes, adducts, and medially rotates the arm at shoulder joint

  Origin: clavicle, sternum, & costal cartilages of upper ribs

  Insertion: humerus
• Deltoid: All fibers contract-abducts arm;anterior fibers flex and medially rotate arm; posterior fibers extend and laterally rotate arm

  Origin: Acromion process &spine of scapula, lateral third of clavicle

  Insertion: Deltoid tuberosity of humerus
• Latissimus dorsi: Extends, adducts and medially rotates lumbar & sacral vertebrae, & lower the arm at shoulder joint

  Origin- Spinous processes of T7-T12,ribs & iliac crest

  Insertion- Humerus
• Triceps brachii: Extends forearm

  Origin:Scapula & humerus

  Insertion:Olecranon process of ulna
• Biceps brachii: Flexes forearm; supinates forearm

  Origin- Scapula

  Insertion- Radial tuberosity
• Brachioradialis: Flexes forearm

  Origin- Lateral border of distal humerus

  Insertion- Base of styloid process of radius
• Flexor carpi ulnaris Flexes hand; adducts hand at wrist

  Origin- Medial epicondyle of humerus & olecranon process of ulna

  Insertion- Carpals & base of metacarpal V
• Extensor carpi ulnaris: Extends hand; adducts hand at wrist

  Origin- Lateral epicondyle of humerus

  Insertion- Base of metacarpal V
• Rectus Abdominus: flexes and rotates lumbar region of vertebral column; compresses abdominal contents

  Origin: Pubic crest and pubic symphysis

  Insertion: posterior surface of femur
• Gluteus maximus Extends thigh at hip; laterally rotates thigh

  Origin- Posterior ilium, sacrum, & coccyx

  Interior- Posterior surface of femur
• Adductor longus Adducts and flexes thigh at hip; mediallyrotates thigh

  Origin- Pubis near pubic symphysis

  Interior- Posterior surface of femur
• Rectus femoris: Extends lower leg and flexes thigh

  Origin- Spine of ilium and upper margin of acetabulum

  Insertion- Patella & tibial tuberosity
• Vastus lateralis: Extends lower leg & stabilizes knee

  Origin- Greater trochanter & posterior femur

  Insertion- Patella & tibial tuberosity
• Vastus medialis: Extends lower leg

  Origin- Medial surface of femur

  Insertion- Patella & tibial tuberosity
• Vastus intermedius: Extends lower leg

  Origin- Anterior & lateral surface of femur

  Insertion- Patella & tibial tuberosity
• Biceps femoris: Extends thigh and laterally rotates leg; flexes lower leg

  Origin- Ischial tuberosity

  Insertion- Head of fibula & lateral condyle of tibia
• Semitendinosus Extends thigh and flexes lower leg; medially rotates leg

  Origin- Ischial tuberosity

  Insertion- Medial surface of tibia
• Semimembranosus: Extends thigh and flexes lower leg; medially rotates leg

  Origin- Ischial tuberosity

  Insertion- Medial condyle of tibia
• Tibialis anterior: Dorsiflexes and inverts foot

  Origin- Lateral condyle & lateral surface of tibia

  Insertion- Tarsal bone & metatarsal I
• Gastrocnemius: Plantar flexes foot and flexes lower leg

  Origin- Lateral & medial condyles of femur

  Insertion- Posterior surface of calcaneus
• Extensor digitorum Dorsiflexion and eversion of footlongus and extends toes

  Origin- Lateral condyle of tibia & anterior surface of fibula

  Insertion- Middle & distal phalanges of toes 2-5