Human Skeleton : The Axial Skeleton & Appendicular Skeleton and Functions of Human Skeleton

Human Skeleton

The human skeleton is the internal framework of bones that provides support and shape to the body. The adult human skeleton typically consists of 206 bones, although the number can vary slightly depending on age, sex, and individual variation.

The human skeleton is divided into two main parts: the axial skeleton and the appendicular skeleton. The axial skeleton includes the bones of the skull, spine, and ribcage, while the appendicular skeleton includes the bones of the limbs and the shoulder and pelvic girdles.

The bones of the human skeleton are made up of a combination of collagen fibers and calcium phosphate mineral. This gives them both strength and flexibility, allowing them to support the weight of the body while also allowing for movement.

In addition to providing support and shape to the body, the human skeleton also protects vital organs such as the brain, heart, and lungs. The bones also serve as attachment points for muscles, allowing the body to move and perform a wide range of activities.

Axial Skeleton

The axial skeleton is one of the two main parts of the human skeleton, the other being the appendicular skeleton. The axial skeleton consists of the bones of the skull, spine, and ribcage.

• The skull is composed of 22 bones that are fused together, with the exception of the mandible (lower jawbone) and the ossicles in the ear. The skull encloses and protects the brain and supports the structures of the face and jaws.
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• The spine, also known as the vertebral column, is composed of 33 individual bones called vertebrae, which are separated by intervertebral discs. The vertebrae are grouped into five regions: cervical (neck), thoracic (upper back), lumbar (lower back), sacral (pelvic), and coccygeal (tailbone). The spine supports the weight of the head and trunk, protects the spinal cord, and allows for movement of the torso.
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• The ribcage, also known as the thoracic cage, is composed of 12 pairs of ribs that attach to the thoracic vertebrae at the back and to the sternum (breastbone) at the front. The ribcage protects the heart, lungs, and other organs in the thoracic cavity, and also assists in breathing by expanding and contracting with each breath.

Overall, the axial skeleton provides support and protection to the vital organs of the body, and allows for movements such as bending, twisting, and turning of the head and torso.

Appendicular Skeleton

The appendicular skeleton is one of the two main parts of the human skeleton, the other being the axial skeleton. It consists of the bones of the limbs and their associated girdles, which attach the limbs to the axial skeleton.

• The upper limb consists of the bones of the shoulder girdle (scapula and clavicle), the arm (humerus), the forearm (radius and ulna), the wrist (8 carpal bones), the hand (5 metacarpal bones), and the fingers (14 phalanges).
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• The lower limb consists of the bones of the pelvic girdle (ilium, ischium, and pubis), the thigh (femur), the leg (tibia and fibula), the ankle (7 tarsal bones), the foot (5 metatarsal bones), and the toes (14 phalanges).
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• The shoulder girdle connects the upper limb to the axial skeleton and allows for a wide range of movement of the arm.
• The pelvic girdle connects the lower limb to the axial skeleton and provides stability for the body when standing or walking.
• The long bones of the limbs are responsible for supporting the weight of the body and allowing for movement, while the smaller bones of the hands and feet provide dexterity and fine motor control.

Overall, the appendicular skeleton allows for a wide range of movement and provides the body with the ability to perform complex tasks such as grasping objects, walking, running, jumping, and dancing.

Functions of Human Skeleton

The human skeleton has several important functions, including:

1. Support: The skeleton provides the framework that supports the body's weight and helps to maintain its shape.
2. Protection: The bones of the skeleton protect the body's internal organs, such as the brain, heart, and lungs.
3. Movement: The skeleton provides attachment points for muscles, allowing the body to move and perform a wide range of activities.
4. Mineral storage: The bones of the skeleton store important minerals, such as calcium and phosphorus, that are necessary for a variety of bodily functions.
5. Blood cell production: The bone marrow within certain bones of the skeleton is responsible for producing red blood cells, white blood cells, and platelets.
6. Energy metabolism: The bone tissue can store energy in the form of lipids, which can be used by the body when needed.

Overall, the functions of the human skeleton are essential for supporting and maintaining the body's structure, protecting its vital organs, allowing for movement and physical activity, and regulating important bodily processes.