Vertebrates, or creatures with a backbone or vertebral column, include humans. They rely on a sturdy internal framework with a prominent spine as the focal point. The human skeletal system is made up of bones, cartilage, ligaments, and tendons, and it accounts for about 20% of the body’s weight.

In metabolism, our bodies’ living bones use oxygen and emit waste products. They are composed of active tissues that absorb nutrients, require blood, and alter form or remodel in response to the  mechanical stress.

The skeleton, which is mostly made up of bones, provides a robust framework for the body’s soft organs to support and protect them.

The skeleton shields the body from gravity’s effects. The enormous bones of the lower limbs support the trunk when standing.

The delicate bodily components are likewise protected by bones. The brain is protected by the fused bones of the cranium, which make it less vulnerable to injury. 

The levels of calcium in the bones is higher than in any organ. Calcium salts, in which the most important calcium phosphate, are abundant in the intercellular matrix  of  the bone.

Microscopic Structure of Bones

The skeleton accounts for 30-40% of an adult’s body weight. The nonliving bone matrix and many small bone cells make up the skeleton’s bulk. Water makes up around half of the bone matrix’s bulk, while collagen protein and solid calcium carbonate and calcium phosphate crystals make up the other half.

On the margins of bones and in small spaces within the bone matrix, living bone cells can be detected. Although these cells make up a small percentage of overall bone mass, they play a critical part in the skeletal system’s operations. Bone cells help bones to: 

• Grow and develop 
• Be mended after an injury or normal wear and tear
• Be broken down to liberate minerals that have been stored in them

SKELETAL SYSTEM ANATOMY

There are two classes of skeletal systems: axial and appendicular. A typical adult body is made up of 206 different bones that are divided into two categories:

• Skeletal axis
• The skeleton of the appendix.

AXIAL SKELETON ANATOMY: The vertebral column (32–34 bones; the number of vertebrae varies from human to human as the lower two portions, sacral and coccygeal bone, may vary in length), a portion of the rib cage (12 pairs of ribs and the sternum), and the skull make up the axial skeleton (80 bones) (22 bones and 7 associated bones).

The axial skeleton, which transmits weight from the head, trunk, and upper extremities to the lower extremities via the hip joints, allows humans to maintain their upright posture. 

Skull bones: The adult skull is made up of 22 bones. These bones can be further categorised based on where they were found:

• • The bones of the skull. The mass of your skull is made up of eight cranial bones. They aid in the protection of your brain.

• The bones of the face. There are 14 bones in the face. They make up the face and are found on the front of the skull.

Auditory ossicles: Six tiny bones in the inner ear canal of the skull are known as auditory ossicles. On each side of the skull, there are three auditory ossicles known as:

• malleus (hammer)

• incus (anvil)
• stapes (stirrup)

They work together to convey sound waves from the outside world to the inner ear’s structures.

Hyoid: A U-shaped bone at the base of the jaw is known as the hyoid. It acts as a site of attachment for the neck’s muscles and ligaments.

Vertebral column: They contain 26 bones. The first 24 vertebrae are all vertebrae, then the sacrum and coccyx (tailbone).

The 24 vertebrae are further classified into the following categories:

• Cervical vertebrae. These 7 bones are present in the head and neck.
• Thoracic vertebrae. These 12 bones are present in the upper back.
• Lumbar vertebrae. The back muscles have all these five bones. 
• Both the sacrum and the coccyx are made up of a number of fused vertebrae. They assist in supporting the body’s weight while sitting. They also act as places of attachment for numerous ligaments.

Thoracic cage: The sternum (breastbone) and 12 pairs of ribs make up the thoracic cage. These bones form a protective cage around the heart and lungs, as well as the organs of the upper torso.

Some ribs are connected to the sternum directly, while others are connected to the sternum via cartilage. Some are referred to as “floating ribs” since they have no connection site.

APPENDICULAR SKELETON ANATOMY: Their primary roles are to allow mobility and to protect the digestive, excretory, and reproductive organs.

There are 126 bones in the appendicular skeleton, comprising the-

• Pelvic girdle
• Upper Limbs
• Lower Limbs
• Shoulder Girdle or the Pectoral

Pectoral girdle: The pectoral girdle is the connection between the arms and the axial skeleton. The clavicle (collarbone) and scapula comprise the clavicle (shoulder blade). Each of these has two of them, one for each arm.

Upper limbs: Both arm contains 30 – 30 bones, known as the:

• • Humerus. The humerus is the largest  bone of the upper arm.
  • Radius. On the thumb side of the forearm, the radius is one of two long bones.
  • Ulna. The ulna is the forearm’s second long bone, located on the pinky finger side.
  • Carpals. The carpals are an eight-bone group found in the wrist.
  • Metacarpals. The metacarpals are a group of five bones in the middle of the hand.

• Phalanges. The fingers contain 14 bones called phalanges.

Pelvic girdle

The pelvic girdle, often known as the hips, is the point at which the legs join the axial skeleton. Two hip bones — one for each leg — make up the hipbone.

Each hip bone is made up of three components, which are referred to as the:

• Ilium. Each hip bone’s top section is known as the ilium.
• Ischium. The ischium is a curving bone near the bottom of each hip bone.
• Pubis. The pubis is a portion of the hip bone that is placed in the front.

Lower limbs: Each leg is made up of 30 bones, which are referred to as the:

• Femur. The femur is the upper leg’s major bone.
• Tibia. The tibia is the lower leg’s primary bone. The shin is formed by it.
• Fibula. The fibula is the second and outermost bone in the lower leg.
• Patella. The patella, often known as the kneecap, is a bone in the lower leg.
• Tarsals. The seven bones that make up the ankle are known as tarsals.
• Metatarsal. The metatarsals are a group of five bones in the middle of the foot.
• Phalanges. The phalanges are the 14 bones which make up the toes.

Healthy skeletal system

In addition to other crucial roles, the skeletal system serves as the foundation for all of the body’s movements.

To keep it in good operating order, follow these guidelines:

• Calcium should be consumed. Leafy green vegetables, broccoli, tofu, and salmon are all calcium-rich foods.
• Make sure you get adequate vitamin D. Most individuals obtain enough of this by spending time outside on a regular basis, but those who live in locations where sunlight is scarce can benefit from a vitamin D supplement.
• Engage in weight-bearing activities. Walking, jogging, and stair climbing are examples of these activities.
• Put on protective gear. To minimise bone fractures and other potentially serious injuries, always use protective gear whether riding a bike or participating in contact sports.

CONCLUSION

The skeletal system serves as the body’s primary framework, and the entire body is built around its hard framework. The skeletal system consists of almost all of the hard or solid portions of the body. Joints play a vital part in the skeletal system because they allow for a variety of movements at various sites. There would be no trace of movement in the human body if the skeleton was devoid of joints.