8 Chapter 8 The Appendicular Skeleton
By Ganesan L. Kamatchi
Motivation.
Gorham-Stout disease is a rare and enigmatic condition involving various skeletal locations. It is also called massive bone disease, vanishing bone disease, phantom bone disease, massive osteolysis, Gorham–Stout syndrome and Gorham’s disease. It is characterized by destruction of osseous matrix and proliferation of vascular structures with benign origin. Despite the extensive investigation of the pathogenetic mechanisms of the disease, its etiology of GSD is poorly understood and the cause of excessive bone resorption in GSD patients has not been clarified. Several studies proposed that the abnormal proliferation of endothelial-lined vessels could promote bone resorption. Bone normally do not have lymphatic vessels and the presence of lymphatics in GSD patients have been confirmed histologically and biochemically. Gorham-Stout disease can affect any part of the skeleton, but the pelvis, long bones, and shoulder girdles are the most frequently involved [Kaissi et al., Medicines (Basel) 6: 54, 2019].
Learning Objectives
Upon completion of the work in this chapter students should be able to:
- Identify and label the pectoral girdle bone structures in the clavicle and scapula samples provided
- Identify the bones of the upper limbs and label their structures
- Label the bones and structures within the pelvic girdle after identifying on an articulated skeleton
- Identify the bones of the lower limbs and label these and their associated structures
Background.
Your skeleton provides the internal supporting structure of the body. The adult axial skeleton consists of 80 bones that form the head and body trunk. Attached to this are the limbs, whose 126 bones constitute the appendicular skeleton (Figure 8.2). These bones are divided into two groups: the bones that are located within the limbs themselves, and the girdle bones that attach the limbs to the axial skeleton. The bones of the shoulder region form the pectoral girdle, which anchors the upper limb to the thoracic cage of the axial skeleton. The lower limb is attached to the vertebral column by the pelvic girdle.
Because of our upright stance, different functional demands are placed upon the upper and lower limbs. Thus, the bones of the lower limbs are adapted for weight-bearing support and stability, as well as for body locomotion via walking or running. In contrast, our upper limbs are not required for these functions. Instead, our upper limbs are highly mobile and can be utilized for a wide variety of activities. The large range of upper limb movements, coupled with the ability to easily manipulate objects with our hands and opposable thumbs, has allowed humans to construct the modern world in which we live.
The Clavicle
The clavicle is the only long bone that lies in a horizontal position in the body (see Figure 8.3). The clavicle has several important functions. First, anchored by muscles from above, it serves as a strut th