Â© 2000 John Wiley & Sons, Inc. An inverse relationship between household income and violence exposure in youth hasbeen reported in numerous studies (e.g., Garbarino & Crouter, 1978; Gelles, 1992; Gelles& Straus, 1979; Steinberg, Catalano, & Dooley, 1981).
The head, attached to the top of the vertebral column, is balanced, moved, and rotated by the neck muscles (). When these muscles act unilaterally, the head rotates. When they contract bilaterally, the head flexes or extends. The major muscle that laterally flexes and rotates the head is the sternocleidomastoid.
Biceps: Long Head. The biceps brachii muscle splits into two tendons at the shoulder: the long head and the short head. The long head of the biceps muscle assists other muscles with shoulder flexion. It is located in the front of the upper arm and attaches to the glenoid fossa, or socket part of the shoulder joint.The long head of the biceps muscle is innervated by the musculocutaneous nerve.he petoralis major is a large, strong muscle that produces shoulder flexion. It is located in the front of the chest and attaches by tendon to the humerus, or upper arm bone.