An Overview of the Two Parts of the Skeleton

As its name suggests, the axial skeleton is the portion of the endoskeleton that lies along the body's central longitudinal (long-jih-TWO-duh-nal) axis. (Carefully study Figure 7.2.) Like the axis of the planet Earth, or the axle of two car wheels, the longitudinal axis forms the ''lengthwise axle'' around which the body turns or pivots. Think of the central longitudinal axis as an imaginary vertical line passing up and down through the middle of the body (much like the body midline).

The word, appendicular, literally ''refers to'' (-ar) ''little attachments'' (appendicul). The appendicular skeleton, then, is the portion of the endoskeleton that is located within the body's appendages (ah-PEN-duh-jes) or ''attachments.'' Being more precise, the appendicular skeleton consists of the bones in all four of the body appendages or limbs (two shoulders and arms, two hips and legs). Of course, the 126 bones in the adult appendicular skeleton are all directly or indirectly attached or ''appended'' to the bones in the axial skeleton.

Real walking stick

Real walking stick

Fig. 7.2 An overview of the axial and appendicular skeletons. White = Bones of the axial skeleton. Black = Bones of the appendicular skeleton.
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