An infant is brought to the clinic by his mother. who has noticed that he holds his head in an unusual position and always faces to one side. Which of the following is the most likely explanation?

Torticollis. with shortening of the sternocleidomastoid muscle.

In torticollis. the sternocleidomastoid muscle is contracted. limiting the range of motion of the neck and causing the chin to point to the opposing side. In craniosynostosis one of the cranial sutures. often the sagittal. closes prematurely. causing the head to grow in an abnormal shape. Plagiocephaly refers to the flattening of one side of the head. caused by the infant being placed supine in the same position over time. Hydrocephalus is caused by a build-up of cerebrospinal fluid in the brain resulting in large head size.