4.1.6 Bones of the upper thorax
Now that we’ve seen the atlas and the axis, we’ll look at the bones below them that are involved in support and movement of the head. The lowest cervical vertebra, the seventh, articulates with the highest of the twelve thoracic vertebrae.
The two first ribs slope downward and forward from the first thoracic vertebra. The costal cartilages of the first two ribs articulate here with the upper part of the sternum, the manubrium.
The manubrium, the first ribs, and the body of the first thoracic vertebra form the margins of this opening, the superior thoracic aperture through which many important structures pass.
To complete our picture of the bones in this section, we'll add the clavicles and the scapulae. On each side the clavicle articulates with the highest part of the manubrium, to form the sterno-clavicular joint. The sternocleidomastoid muscle is inserted here.
The scapula is attached to the clavicle here, at the acromio-clavicular joint. In addition the scapula is held in place by powerful muscles, the highest of which, the trapezius, arises here on the skull, and is inserted here.