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.
Pull head back as far possible while looking slightly down. Hold stretch. Neck retraction primarily consists of Cervical Flexion (spine) accompanied by subtle Thoracic Flexion (spine) and Neck Flexion (atlanto-occipital joint). Cervical spine has natural lordotic curvature (see diagram of spine). Much of the retraction motion is actually flattening or slight reversing the normal lordosis.