The tendons of the _ and _ wrap the humerus from back toward front, so that contraction rotates the humerus laterally. Tendon connecting the _ to its insertion ( on the lesser tubercle of the humerus) wraps around the humerus from front toward back, so that contraction spins the humerus medially. The _ extends the shoulder by pulling the inter tubercular groove of the humerus toward the vertebral column. The _ flexes the shoulder from the abducted position by pulling the inter tubercular groove of the humerus toward the sternum. The _ portion of the _ is used to flex the shoulder from the adducted position by pulling the interubercular groove of the humerus toward the sternum. The _ and _ act together to pull the inntertubercular groove of the humerus toward the ribcage: one pulls toward the front, and the other toward the back. When the _ and _ on one side of the body contract together, rotation is prevented, and the lateral ribcage is pulled toward the iliac crest.Ĭontraction of the entire _ pulls a tuberosity of the humerus toward the clavicle and scapula.įor abduction beyond horizontal (to bring arm above head) the _ and _ must raise and rotate the scapula, so that the glenoid cavity faces upward.
(there are several synergists neraby.) they are visible in the lumbar region: above this, they rare deep to ot The _ pull superior ribs and vertebral process toward relatively inferior vertebral processes and the dorsal iliac crests, extending the back. The _, a pair of segmented muscles, pulls the xiphoid process and costal cartilages of the ribs toward the pubic crest and symphysis, thereby flexing the lumbar vertebrae. Most of the synergists for the internal and external obliques are fairly distant:they are found _. Portions of the _ pull the anterior ribcage toward relatively posterior portions of the iliac crest, and the lumbar fascia
The _pull posterior regions of the ribs toward the mid-line of the abdomen, the pubic crest, and relatively anterior portions of the iliac crest. Unilateral contraction of the _ muscles rotates head toward the contracting side.Ĭontracting the _ and the _ on the same side results in tilting of the head toward that side.Ĭontracting the _ on one side of the body and the _ on the other rotates the thorax relative to the pelvis. Unilateral contraction of the _ rotates head away from contracting side. If the scapulae are fixed, the _ is also a powerful neck extensor.Ĭontracting the _ on one side and the _ on the other side results in head rotation If the muscles on both sides of the body contract together, the neck is extended or hyperextended. The _ pull the mastoid process and transverse processes of C2 to C4 toward the spinous process of C7 through T6. When both contract together, they flex the neck. The _ (one on each side) pull the mastoid process of the skull toward the sternum and clavicle. The _ has two bellies held together by a tendon which runs through a fibrous loop on the hyoid.Ĭontraction of the _ pulls the mandible down toward the hyoid., if movement of the hyoid is prevented by a contraction of the _. The _ is the prime mover in jaw elevation: it pulls the ramus of the madible toward the zygomatic arch. The _ pulls the coronoid process of the mandible toward the temple, deep to the zygomatic arch. (they provide the "front" motion in grinding while chewing- contracting one side at a time helps produce side to side grinding as well.) Synergists which stabilize a muscle's origin so that it does not move during contraction are called _. extensors and flexors around a common joint. _ are pairs of muscles which lengthen one another: e.g. They are not covered in this question bank in detail, but are involved in almost all movements. _ are pairs of muscles which assist in a particular movement by adding force, stability, or direction. _ provide the major force for producing a specific movement. (true/false) after a muscle contraction ends and the muscle relaxes, it automatically returns to its resting length. (true/false) a muscle cannot lengthen itself. Direction of a muscle's pull is determined by the direction of the _.
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