Which of the following is not part of the pectoral girdle?

• A. Humerus
• B. Clavicle
• C. Acromion
• D. Scapula

Answer: (A)

Verified step by step guidance

1. Understand the components of the pectoral girdle: The pectoral girdle, also known as the shoulder girdle, consists of bones that connect the upper limb to the axial skeleton. It primarily includes the clavicle and the scapula.
2. Identify the role of each component: The clavicle, or collarbone, serves as a strut between the shoulder blade and the sternum. The scapula, or shoulder blade, provides attachment points for muscles and articulates with the humerus at the shoulder joint.
3. Recognize the acromion: The acromion is a bony process on the scapula. It forms the highest point of the shoulder and is part of the scapula, thus part of the pectoral girdle.
4. Consider the humerus: The humerus is the long bone in the upper arm. It articulates with the scapula at the shoulder joint but is not part of the pectoral girdle itself.
5. Conclude which is not part of the pectoral girdle: Based on the understanding that the pectoral girdle consists of the clavicle and scapula (including the acromion), the humerus is not part of the pectoral girdle.