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.
Lower Cervical Spine. The 5 cervical vertebrae that make up the lower cervical spine, C3-C7, are similar to each other but very different from C1 and C2. Each has a vertebral body that is concave on its superior surface and convex on its inferior surface (see the image below).