Arno

Part of the human skeleton that includes the limbs and girdles

The appendicular skeleton is a major division of the human skeleton that includes the bones of the limbs and the supporting girdles. It is essential for movement and interaction with the environment, providing attachment points for muscles and facilitating locomotion.

Structure

The appendicular skeleton is composed of 126 bones and is divided into two main regions: the upper and lower limbs, along with their respective girdles.

Upper Limb

The upper limb consists of the following components:

• Pectoral girdle: Comprising the clavicle and scapula, the pectoral girdle connects the upper limb to the trunk and provides attachment points for muscles.
• Arm: The arm contains the humerus, which is the single bone of the upper arm.
• Forearm: The forearm consists of two bones, the radius and ulna, which allow for the rotation of the wrist.
• Hand: The hand is made up of the carpal bones (wrist), metacarpal bones (palm), and phalanges (fingers).

Lower Limb

The lower limb includes the following components:

• Pelvic girdle: Formed by the hip bones, the pelvic girdle connects the lower limb to the axial skeleton and supports the weight of the upper body.
• Thigh: The thigh contains the femur, the longest and strongest bone in the body.
• Leg: The leg is composed of the tibia and fibula, which support the body's weight and allow for movement.
• Foot: The foot includes the tarsal bones (ankle), metatarsal bones (midfoot), and phalanges (toes).

Function

The appendicular skeleton serves several critical functions:

• Movement: It provides the framework for muscle attachment, enabling movement and locomotion.
• Support: It supports the weight of the body, particularly in the lower limbs.
• Protection: It protects vital organs, such as the pelvis protecting the reproductive organs.
• Storage: It stores minerals, such as calcium and phosphorus, which are essential for various bodily functions.

Development

The appendicular skeleton develops from the mesoderm during embryonic development. The process involves the formation of cartilage models, which are gradually replaced by bone through endochondral ossification.

Clinical Significance

Disorders of the appendicular skeleton can significantly impact mobility and quality of life. Common conditions include:

• Fractures: Breaks in the bones due to trauma or stress.
• Arthritis: Inflammation of the joints, leading to pain and stiffness.
• Osteoporosis: A condition characterized by decreased bone density, increasing the risk of fractures.

Related pages

• Axial skeleton
• Human skeleton
• Bone
• Joint

Gallery

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  Diagram of the appendicular skeleton