Appendicular Skeleton: Pectoral (Shoulder) Girdle

Appendicular Skeleton

Pectoral (Shoulder) Girdle

The pectoral girdle is a key anatomical structure that connects the upper limb to the axial skeleton, providing both support and mobility. It consists of two bones and serves as an attachment site for muscles that move the shoulder and arm.

• Composed of two bones: Clavicle and Scapula

• Attachment Points: Provides attachment for many trunk and neck muscles, facilitating movement and stability.

• Mobility: The pectoral girdle allows exceptional mobility for the upper limb due to its structure and loose attachments.

• Clavicular Joints: The sternoclavicular joints are the only direct bony attachment of the pectoral girdle to the axial skeleton (the trunk).

• Scapular Attachment: The scapula is loosely attached, allowing it to glide over the thorax and providing a wide range of motion.

• Glenoid Cavity: The shallow glenoid cavity of the scapula is where the head of the humerus fits, forming the shoulder joint.

Example: The ability to raise, rotate, and move the arm in multiple directions is due to the unique structure and mobility of the pectoral girdle.

Anatomical Landmarks and Clinical Relevance

• Clavicle: Acts as a strut to keep the scapula in position, allowing the arm to hang freely.

• Scapula: Has several important borders and angles, such as the medial border and inferior angle, which are palpable and serve as muscle attachment sites.

• Winged Scapula: A clinical condition where the medial border of the scapula protrudes posteriorly, often due to weakness or paralysis of the serratus anterior muscle.

Example: The image of a right winged scapula demonstrates the prominence of the medial border and inferior angle, which can be observed in certain neuromuscular disorders.

Visual Reference: Pectoral Girdle Anatomy

• Anterior View: Shows the relationship of the clavicle and scapula to the sternum and ribs.

• Posterior View: Highlights the scapula's position on the back and its articulation with the clavicle.

Additional info: The pectoral girdle's loose attachment and shallow glenoid cavity contribute to the shoulder's susceptibility to dislocation but also its remarkable range of motion.