Anatomy: The muscles on the back of the upper arm (brachium) comprise the 3-headed arm stretcher (M triceps brachii). The muscle primarily stretches the elbow joint (and the shoulder joint). 1  Clavicula.  Bursa subcutanea acromialis.
Overview. The cervical spine is made up of 7 vertebrae. The first 2, C1 and C2, are highly specialized and are given unique names: atlas and axis, respectively. C3-C7 are more classic vertebrae, having a body, pedicles, laminae, spinous processes, and facet joints.
The lumbar spine (low back) is made up of five lumbar vertebrae (backbones) that are separated by five intervertebral discs (discs), the lowest of which sits on top of a large triangular shaped bone called the sacrum.he lumbar spine (low back) is made up of five lumbar vertebrae (backbones) that are separated by five intervertebral discs (discs), the lowest of which sits on top of a large triangular shaped bone called the sacrum.