Appendicular Skeleton

Overview of the Human Skeleton

The human skeleton is a complex framework composed of at least 206 bones. It is divided into two major sections: the axial skeleton and the appendicular skeleton. The appendicular skeleton consists of 126 bones and is primarily responsible for facilitating movement and supporting the limbs.

• Axial skeleton: Includes 80 bones forming the central axis (skull, vertebral column, rib cage).

• Appendicular skeleton: Includes 126 bones of the limbs and girdles (shoulder and pelvic regions).

Shoulder Girdle

Clavicle

The clavicle, commonly known as the collar bone, is a slender, S-shaped bone that connects the upper limb to the trunk. It serves as a strut to keep the scapula in place, allowing for maximum range of motion of the arm.

• Sternal end: The rounded, medial end that articulates with the sternum (breastbone).

• Acromial end: The flattened, lateral end that articulates with the acromion of the scapula.

• Orientation: To determine if a clavicle is right or left, the acromial end must point forward and the inferior side of the bone must be underneath.

Function: The clavicle acts as a brace for the shoulder, transmitting mechanical force from the upper limb to the axial skeleton.

Scapula

The scapula, or shoulder blade, is a flat, triangular bone located on the posterior side of the rib cage. It provides attachment points for several muscles and articulates with both the clavicle and humerus.

• Spine of scapula: A prominent ridge running across the posterior surface, dividing it into the supraspinous and infraspinous fossae.

• Acromion process: The lateral extension of the spine, articulates with the clavicle.

• Coracoid process: A hook-like projection on the anterior surface, serves as an attachment for muscles and ligaments.

• Glenoid cavity: A shallow socket that articulates with the head of the humerus, forming the shoulder joint.

• Angles and borders: Includes the superior, inferior, and lateral angles, as well as the superior, medial (vertebral), and lateral (axillary) borders.

Function: The scapula stabilizes the arm and provides a surface for muscle attachment, enabling a wide range of shoulder movements.

Key Features Table: Clavicle and Scapula

Additional info:

• The appendicular skeleton also includes the bones of the upper and lower limbs, as well as the pelvic girdle, which are covered in further detail in extended study materials.

• Correct identification of right and left bones is essential for anatomical study and clinical practice.