Topic # 13.1: Human Skeleton(Axial Skeleton and Appendicular Skeleton)

Slo # 13.1.1: Define Skeleton and differentiate between cartilage and bones; Knowledge + Understanding.

Made by : -Awais -Nabeel

Skeleton (anatomy), term applied to all the rigid or semirigid structures supporting the soft tissues of an animal's body and providing leverage for muscular action. In vertebrates, the skeleton is known as the endoskeleton and is formed within the body. Some invertebrate animals, such as insects and crustaceans, have skeletons known as exoskeletons on the outside of the body.

... The human skeleton consists of 206 bones. Many of which move or hinge at joints. In conjunction with over 600 muscles these bones enable the human body to achieve a variety of movements.

The functions of the skeleton include: -

To provide a large surface area for the attachment of muscles.

To give shape to the body. To give support to the body.

Cartilage, or gristle, fibrous connective tissue found in humans and vertebrate animals that provides support to the skeleton at specific sites throughout the body. Cartilage is composed of specialized cells, called chondrocytes, surrounded by a gelatinous matrix of collagen, a tough protein. The cartilage surface is covered by a membrane known as the perichondrium.

The skeleton of vertebrate fetuses is composed largely of cartilage, which is eventually replaced by bone. Some cartilage persists into adulthood. It is fibrous and rubbery, providing support, flexibility, and elasticity to the ends of bone tissue and to the nose, ears, breastbone, trachea, larynx, joints, and other parts of the body. Some animal skeletons, such as that of the shark, are completely cartilaginous

External ear Nose “Articular” – covering

the ends of most bones and movable joints

“Costal” – connecting ribs to sternum

Larynx - voice box

Epiglottis – flap keeping food out of lungs

Cartilaginous rings holding open the air tubes of the respiratory system (trachea and bronchi)

Intervertebral discs Pubic symphysis Articular discs such as

meniscus in knee joint

Bone (anatomy), hard connective tissue, the major component of almost all skeletal systems in adult vertebrate animals. bone actually is a dynamic structure composed of both living tissues, such as bone cells, fat cells, and blood vessels, and nonliving materials, including water and minerals.

Bones are multipurpose structures that play diverse, vital roles in vertebrates. They provide a framework for the body, supporting it and giving it shape. They also provide a surface for the attachment of muscles and act as levers, permitting many complex movements. Many bones protect softer internal organs; for example, skull bones protect the brain, and rib bones form a cage around the lungs and heart. In addition to these structural and mechanical functions, bones also participate in the body’s physiology. They store calcium, a mineral essential for the activity of nerve and muscle cells. The soft core of bone, the bone marrow, is the site of formation of red blood cells, certain white blood cells, and blood platelets

An adult human has 206 bones, which account for 14 percent of the body’s total weight. The longest and strongest bone is the thighbone, which at maturity is about 50 cm (20 in) long and 2.5 cm (1 in) wide. The smallest bone, the stirrup bone, is one of three tiny bones buried within the middle ear; it is only 0.18 cm (0.07 in) long.

Functions Support Movement: muscles attach by tendons and

use bones as levers to move body Protection

Skull – brain Vertebrae – spinal cord Rib cage – thoracic organs

Mineral storage Calcium and phosphorus Released as ions into blood as needed

Blood cell formation and energy storage Bone marrow: red makes blood, yellow stores fat

Long bones Short bones Flat bones Irregular

bones Pneumatize

d bones Sesamoid

bones

(Short bones include sesmoid bones)

Intimately associated with bone is another type of connective tissue called cartilage. Cartilage is softer, more elastic, and more compressible than bone. It is found in body parts that require both stiffness and flexibility, such as the ends of bones, the tip of the nose, and the outer part of the ear.Microsoft ® Encarta ® 2009. © 1993-2008 Microsoft Corporation. All rights reserved.