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Muscles of the Body Muscles of the Body • Ligaments connect bone to bone • Tendons connect muscle to bone • The origin of a muscle is the attachment of a muscle’s tendon to the stationary bone • The insertion of a muscle is the attachment of the muscle’s other tendon to the moveable bone • In producing movement, bones act as levers and joints function as the fulcrums of these levers • Movement is produced by a mechanical advantage Archimedes (287 - 212 B.C.) • Scientist, mathematician, and engineer of ancient Greece • Invented a planetarium • Invented a hydraulic musical organ • Invented the Screw of Archimedes, which moved water uphill • Figured out while taking a bath how to tell whether King Hiero’s crown was made of gold, and ran naked through the streets shouting “Eureka!” • Invented a machine to lever ships between the dock and the water “Give me a lever long enough, and a place to stand, and I will move the earth.” Fascicle Arrangement Learn How Muscles Are Named! Learn How Muscles Are Named! Muscles of Facial Expression • Orbicularis oris = kissing muscle • Occipitofrontalis (frontal belly) = surprise muscle • Zygomaticus major = smile muscle • Buccinator = whistling muscle • Orbicularis oculi = winking muscle • Corrugator supercilii = scowl muscle • Zygomaticus minor = snarl muscle • Mentalis = pout muscle • Risorius = grimace muscle Botox! Muscles That Move the Eyeballs • All rectus muscles originate on the common tendinous ring attached to orbit around optical foramen • Superior oblique originates on sphenoid • Inferior oblique originates on maxilla • All rectus muscles insert on the eyeball on the same side as their name • Oblique muscles insert on the eyeball between the adjacent rectus muscles Muscles of the Head and Neck • Platysma depresses the mandible and also “pouts” • Occipitofrontalis (occipital belly) draws scalp posteriorly • Masseter elevates the mandible • Temporalis elevates and retracts the mandible • Medial pterygoid elevates and retracts the mandible • Lateral pterygoid depresses and protracts the mandible Muscles of the Head and Neck • Digastric elevates the hyoid and depresses the mandible • Stylohyoid elevates the hyoid • Both originate at least in part on the temporal bone, and insert on the hyoid • Useful in speaking and swallowing • Omohyoid originates on the scapula and depresses the hyoid • Sternohyoid originates on the clavicle and sternum, and depresses the hyoid • Once again useful in speaking and swallowing Muscles of the Head and Neck • Sternocleidomastoid laterally extends and rotates the head to the side opposite the muscle • Originates on the sternum and clavicle • Inserts on the mastoid process of the temporal bone Muscles That Move the Shoulder Girdle • Trapezius (posterior): elevates and adducts the scapula • Levator scapulae (posterior): elevates and rotates scapula • Rhomboid major (posterior): elevates and adducts scapula • Pectoralis minor (anterior): abducts scapula, elevates ribs 3 - 5 • Serratus anterior (anterior): abducts scapula, elevates ribs, the “boxer’s muscle” Muscles That Move the Arm • Supraspinatus: assists in abducting the arm • Infraspinatus: laterally rotates and adducts arm • Subscapularis: medially rotates arm • Teres major: extends, adducts, and medially rotates arm • Teres minor: extends, adducts, and laterally rotates arm • Deltoid: abducts arm Muscles That Move the Arm • Supraspinatus, infraspinatus, subscapularis, and teres minor form the rotator cuff • These muscles and their tendons form a cuff or sleeve around the shoulder joint • The supraspinatus is most commonly affected • The muscle tears, or suffers impingement of the tendon • Common in baseball players, swimmers, tennis players, and various workers Muscles That Move the Arm The rotator cuff Muscles That Move the Arm • Pectoralis major: adducts and medially rotates the arm • Originates on the clavicle, sternum, and costal cartilages • Inserts on the humerus • Latissimus dorsi: extends, adducts, and medially rotates the arm • Originates on vertebrae, sacrum, ilium, and ribs • Inserts on the humerus Muscles That Move the Forearm • Triceps brachii: extends forearm • Lateral and medial heads originate on the humerus • Long head originates on infraglenoid tubercle • Insert on the olecranon process of the ulna • Brachialis: flexes forearm • Biceps brachii: flexes and supinates forearm • Short head originates on coracoid process of scapula • Long head originates on tubercle above glenoid cavity • Inserts on the radial tuberosity • Originates on the humerus • Inserts on the ulna Muscles That Move the Forearm • Supinator: supinates forearm • Originates on the lateral epicondyle of the humerus • Inserts on the radius • Pronator teres: pronates forearm • Originates on the medial epicondyle of the humerus • Inserts on the radius • Brachioradialus: flexes the forearm, pronates and supinates back to neutral position • Originates on the humerus • Inserts on the radius Muscles That Move the Wrist • Flexor digitorum superficialis, Flexor carpi radialis, Flexor carpi ulnaris, and Palmaris longis • All originate at least in part on the medial epicondyle of the humerus • All insert on the carpals or phalanges • Flexor pollicis longus flexes the thumb • It originates on the interosseous membrane and inserts on the thumb Muscles That Move the Wrist • Extensor carpi radialis longus/brevis, Extensor carpi ulnaris, and Extensor digitorum all extend the hand and digits • All originate at least in part on the lateral epicondyle of the humerus • All insert on the metacarpals or phalanges • Abductor pollicis longus abducts the hand and thumb, and extends the thumb • It originates on the interosseous membrane and inserts on the first metacarpal Muscles That Move the Wrist • Extensor pollicis longus/brevis extend the thumb and abduct the hand • Both originate at least in part on the interosseus membrane • Both insert on the thumb Muscles of the Thorax • The diaphragm produces inhalation when it contracts, exhalation when it relaxes • It originates on the xiphoid process, as well as some vertebrae and ribs • It inserts on the central tendon QuickTime™ and a Animation decompressor are needed to see this picture. Muscles of the Thorax • Contraction of the external intercostals elevates the ribs during inhalation, relaxation depresses the ribs during exhalation • They originate on the inferior border of the rib above, and insert on the superior border of the rib below • Contraction of the internal intercostals draws the ribs together during exhalation • They originate on the superior border of the rib below, and insert on the inferior border of the rib above Muscles That Move the Thigh • Psoas major and iliacus flex and rotate the thigh laterally • Both insert on the lesser trochanter of the femur • Tensor fasciae latae flexes and abducts the thigh • It originates on the iliac crest and inserts on the tibia • Pectineus flexes and adducts the thigh • It originates on the pubis and inserts on the femur • Adductor longus adducts and flexes the thigh • It originates on the pubis and ischium and inserts on the femur Muscles That Move the Thigh • Adductor magnus adducts and laterally rotates the thigh • It originates on the ischium and pubis and inserts on the linea aspera of the femur • Gracilis adducts and medially rotates the thigh • It originates on the pubis and inserts on the tibia Muscles That Move the Thigh • Gluteus maximus extends and laterally rotates the thigh • It originates on the iliac crest, sacrum, and coccyx • It inserts on the femur • Gluteus medius abducts and medially rotates the thigh • It originates on the ilium • It inserts on the greater trochanter of the femur Muscles That Move the Leg • Sartorius flexes the leg, also flexes, abducts, and laterally rotates the thigh • It originates on the ilium and inserts on the tibia • Sartorius is the longest muscle in the body • Rectus femoris, vastus lateralis, vastus medialis, and vastus intermedius together form the quadriceps femoris, which extend the leg • All originate on the ilium or femur • All insert on the patella and the tibia Muscles That Move the Leg • Biceps femoris flexes the leg and extends the thigh • The long head originates on the ischium and the short head on the femur • Inserts on the tibia and fibula • Semitendinosus and semimembranosus flex the leg and extend the thigh • Both originate on the ischial tuberosity • Both insert on the tibia • All three muscles together are known as the hamstrings Muscles That Move the Foot • Tibialis anterior dorsiflexes and inverts the foot • It originates on the tibia and inserts on the first metatarsal and cuneiform • Soleus plantar flexes the foot • It originates on the fibula and tibia and inserts on the calcaneus • Fibularis longus/brevis (peroneus) plantar flex and evert the foot • Fibularis longus originates on the tibia and fibula and inserts on the first metatarsal and first cuneiform • Fibularis brevis originates on the fibula and inserts on the fifth metatarsal Muscles That Move the Foot • Gastrocnemius plantar flexes the foot, and flexes the leg • It originates on the condyles of the femur and inserts on the calcaneus • Flexor digitorum longus plantar flexes the foot and flexes the toes • It originates on the tibia and inserts on the distal phalanges 2 - 5 • Flexor hallucis longus plantar flexes the foot and flexes the great toe • It originates on the fibula and inserts on the great toe