Lab 5: Skeletal System II – Appendicular Skeleton and Joints
Lab 5: Skeletal System II – Appendicular Skeleton and Joints
Appendicular Skeleton, Articulations
When you are prepared for the Test on Week 5 Learning Objectives in Week 6, you will be able to:
- Identify the bones of the appendicular skeleton.
- Identify major morphological features of the appendicular skeleton, which bones they are located in, and their functions (listed in the lab activity).
- Identify the bony features that are the attachment sites for the rotator cuff, hamstrings, and quadriceps.*
- Classify joints structurally (cartilaginous, fibrous, or synovial) and functionally (synarthroses, amphiarthroses, or diarthroses).
- Identify components of a typical synovial joint.
- Identify components of the knee joint.
*W5 will particularly focus on the rotator cuff; the hamstrings and quadriceps attachment sites will be revisited in W7
The Appendicular Skeleton
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 5.1). 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 shoulder 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.
The Shoulder Girdle
The bones that attach each upper limb to the axial skeleton form the shoulder girdle (pectoral girdle). This consists of two bones, the scapula and clavicle (Figure 5.2). The clavicle (collarbone) is an S-shaped bone located on the anterior side of the shoulder. It is attached on its medial end to the sternum of the thoracic cage, which is part of the axial skeleton. The lateral end of the clavicle articulates (joins) with the scapula just above the shoulder joint. You can easily palpate, or feel with your fingers, the entire length of your clavicle.
The scapula (shoulder blade) lies on the posterior aspect of the shoulder. It is supported by the clavicle, which also articulates with the humerus (arm bone) to form the shoulder joint. The scapula is a flat, triangular-shaped bone with a prominent ridge running across its posterior surface. This ridge extends out laterally, where it forms the bony tip of the shoulder and joins with the lateral end of the clavicle. By following along the clavicle, you can palpate out to the bony tip of the shoulder, and from there, you can move back across your posterior shoulder to follow the ridge of the scapula. Move your shoulder around and feel how the clavicle and scapula move together as a unit. Both of these bones serve as important attachment sites for muscles that aid with movements of the shoulder and arm.
The right and left shoulder girdles are not joined to each other, allowing each to operate independently. In ad