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Human Muscles
20 required muscle names and actions
| Question | Answer |
|---|---|
| orbicularis oculi | Closure of eyelids |
| orbicularis oris | Closes and protudes lips; compresses lips against teeth |
| temporalis | Elevates and retracts mandible, assists in side to side movement of mandible. |
| masseter | Elevates mandible and slightly protracts it. |
| sternocleidomastoid | Contraction of one side--bends neck laterally and rotates head to opposite side. |
| diaphragm | Flattens on contraction increasing the vertical dimensions of thorax |
| rectus abdominis | Compresses the abdominal cavity and flexes the verebral column |
| external oblique | Compresses the abdominal cavity. Laterally flexes and rotates vertebral column. Both sides flex verebral column anteriorly. |
| internal oblique | Compresses abdominal contents, laterally bends and rotates verebral column. It also aids the rectus abdominis in flexing verebral column. |
| pectoralis major | Adducts and medially rotates arm, clavicular head flexes humerus, sternal head extends humerus, and with insertion fixed it assists in elevation of the thorax. |
| pectoralis minor | With ribs flexed, it draws the scapula forward and downward, and with scapula fixed, it draws the rib cage superiorly. |
| serratus anterior | Abducts and protracts the scapula, rotates it so that the glenoid cavity faces cranially. It also holds the scapula firmly against the thorax. |
| trapezius | Stabilizes, raises, retracts and rotates the scapula. The superior fibers elevate, the middle fibers retract, and the inferior fibers depress the scapula. Together the upper and lower fibers rotate the arm. |
| latissimus dorsi | Extends, adducts and medially rotates the arm; draws the shoulder downward and backward. |
| deltoid | Anterior portion--flexion and medial rotation of the arm. Middle portion--abducts the arm. Posterior portion--extends and laterally rotates the arm. |
| subscapularis | Medially rotates and stablilizes the head of the humerus in the glenoid cavity. |
| supraspinatus | Abducts the arm and acts to stabilize the humeral head in the glenoid cavity during movements of the shoulder joint. One of four "rotator cuff" muscles. |
| infraspinatus | Lateral rotation of the shoulder and acts to stabilize the humeral head in the glenoid cavity. It is one of the "rotator cuff" muscles. |
| biceps brachii | Flexes and supinates the forearm. |
| triceps brachii | Extends the forearm and the tendon of the long head helps stabilize the shoulder joint. |
| flexor digitorum superficialis (in antebrachium) | Flexes the wrist and the middle phalanges of fingers two through five. |
| quadratus femoris | Laterally rotates the thigh at the hip joint. |
| glueteus maximus | Upper part--extends and laterally rotates thigh. Lower part--extends, laterally rotates thigh and assists in raising the trunk from a flexed position. Also assists in adduction of the hip joint. |
| gluteus medius | Abducts the hip joint and medially rotates the thigh. |
| gluteus minimus | Abducts the fermur at the hip joint and medially rotates the thigh. |
| tensor fascia latae | Assists in abduction, medial rotation, and flexion of thigh. Makes the iliotibial tract taut. Stabilizer of the hip. |
| sartorius | Flexes, laterally rotates, and abducts the hip joint. Also flexes the torso toward the leg, and flexes and assists in medial rotation of the knee. |
| rectus femoris | Extends the leg at the knee and flexes the thigh at the hip joint. |
| vastus medialis | Extends the leg at the knee joint and draws the patella medially. |
| vastus lateralis | Extends the knee joint and exerts a lateral pull on the patella. |
| vastus intermedius | Extends the knee at the joint. |
| biceps femoris | Flexes and laterally rotates the knee joint and extends the thigh. |
| gracilis | Adducts thigh at hip joint and flexes leg at knee joint. Assists in medial rotation. |
| gastronemius | Plantar flexion of the ankle joint and assists in flexion of the knee joint. |
| soleus | Plantar flexion of the ankle and stabilizes the leg over the foot. |
| flexor digitorum longus (in leg) | Flexes distal phalanges of lateral four toes, assists in plantar flexion of foot, inverts foot. |
| tibialis anterior | Dorsiflexion of the foot at the ankle joint and inversion of the foot. |
| peroneus longus | Plantar flexion and eversion of the foot. |