Appendicular Skeleton

Overview of the Appendicular Skeleton

The appendicular skeleton consists of the bones of the limbs and the girdles that attach them to the axial skeleton. It plays a crucial role in movement and manipulation of the environment.

• Main Components: Pectoral (shoulder) girdle, upper limbs, pelvic (hip) girdle, and lower limbs.

• Function: Facilitates locomotion and interaction with surroundings.

• Attachment: Girdles connect the limbs to the axial skeleton.

Pectoral (Shoulder) Girdle

Structure and Articulations

The pectoral girdle attaches the upper limb to the trunk and provides mobility and flexibility to the shoulder region.

• Bones: Clavicle (collarbone) and scapula (shoulder blade).

• Articulations:

  • Sternoclavicular joint: Clavicle articulates with the sternum (axial skeleton).

  • Acromioclavicular joint: Clavicle articulates with the scapula.

  • Glenohumeral joint: Scapula articulates with the humerus (upper arm bone).

• Mobility: The pectoral girdle does not articulate directly with the vertebral column; it is stabilized by muscles.

Clavicle (Collar Bone)

The clavicle is a slender, S-shaped bone that acts as a strut to keep the upper limb away from the thorax, allowing for maximum range of motion.

• Medial end: Articulates with the sternum at the sternoclavicular joint.

• Lateral end: Articulates with the scapula at the acromioclavicular joint.

• Function: Transmits mechanical force from the upper limb to the axial skeleton.

Scapula (Shoulder Blade)

The scapula is a flat, triangular bone located on the posterior thoracic wall. It provides attachment for several muscles and forms part of the shoulder joint.

• Key Features:

  • Acromion process: Articulates with the clavicle.

  • Glenoid cavity (fossa): Articulates with the head of the humerus to form the shoulder joint.

  • Coracoid process: Serves as an attachment for muscles and ligaments.

• Function: Provides a stable base for arm movement and muscle attachment.

Learning Objectives (from Session Outline)

• Identify the bones of the pectoral girdle and describe their articulations.

• Describe the bones of the upper limb and their main features.

• Explain the structure and function of the carpal tunnel.

• Identify the bones of the pelvic girdle and describe the function of the acetabulum.

• Distinguish between male and female pelvis.

• Differentiate between the false pelvis and true pelvis and explain their clinical significance.

• Compare the structural differences between the pectoral and pelvic girdles.

• Describe the bones of the lower limb and their main features.

• Explain the structure and function of the arches of the foot.

Key Terms and Definitions

• Appendicular Skeleton: The portion of the skeleton consisting of the limbs and girdles.

• Pectoral Girdle: The set of bones (clavicle and scapula) that attach the upper limb to the trunk.

• Pelvic Girdle: The set of bones (hip bones) that attach the lower limb to the trunk.

• Glenohumeral Joint: The ball-and-socket joint between the scapula and humerus.

• Acromioclavicular Joint: The joint between the acromion of the scapula and the clavicle.

• Sternoclavicular Joint: The joint between the sternum and the clavicle.

Example: Clinical Relevance

• Clavicle Fracture: The clavicle is one of the most commonly fractured bones due to its subcutaneous position and role in force transmission.

• Shoulder Dislocation: The glenohumeral joint is highly mobile but less stable, making it prone to dislocation.

Additional info: Further details on the bones of the upper and lower limbs, carpal tunnel, pelvic girdle, and arches of the foot would be covered in subsequent sections or slides.