10.1:
Introduction to the Skeletal System
The human skeletal system comprises bones and other connective tissue, including cartilage and ligaments.
Bones are hard and rigid structures that give shape and posture to the human body.
Some bones form protective structures, such as the rib cage and the skull, that help prevent trauma to vital organs and soft tissue.
Others, such as the bones in limbs, act as levers to facilitate body movements directed by the skeletal muscles.
These muscles are attached to bones via tendons, which transmit the pulling forces from the muscles to the bones enabling movement.
Similarly, another type of dense connective tissue, the ligaments, connect one bone to another. They stabilize the position of the bones and also allow movement at the joints.
Additionally, such movable joints are cushioned by cartilage, which functions as a shock absorber and reduces friction during movement.
Due to its flexibility and tensile strength, cartilage tissue also provides support and shape to some body parts. For example, the costal cartilages allow the forward expansion of the rib cage, and the tracheal rings give shape and support to the trachea.
10.1:
Introduction to the Skeletal System
The skeletal system is the central framework of the body, consisting of different connective tissues: bones, cartilage, tendons, and ligaments.
Components of the Skeletal System
Bone, or osseous tissue, is a hard connective tissue that forms an internal support structure for the human body. Bones shield vulnerable organs and soft tissue from external forces. For example, the vertebral bones protect and support the spinal cord.
Cartilage, a semi-rigid connective tissue found in regions such as the joints and rib cage, provides flexibility and smooth surfaces for ease of movement. Ligaments and tendons are dense, elastic tissue that connect one bone to another or bones to muscles, respectively. Whereas ligaments stabilize bones, tendons transfer the force of muscle contraction to the bones.
Male, Female, and Newborn Skeletal Systems
The adult human skeleton is made up of 206 bones. In contrast, newborns have as many as 270 or more bones, many of which are largely cartilaginous and gradually fuse over time as the baby develops. In children, the cartilage in the epiphyseal plate of long bones is actively dividing and contributes to bone growth until adolescence, when the cartilage ossifies and forms the epiphyseal line. Girls develop a wide and long pelvis that is better adapted for childbirth; whereas boys develop broad shoulders and a long rib cage. A male skeleton also differs from that of a female in having bigger bones, especially the skull, arm bones, and leg bones. These differences between male and female skeletons are significant enough to correctly identify the age and gender of a skeleton with 95% accuracy.
Part of this text is adapted from Openstax, Anatomy and Physiology 2e, Section 6.1: The Functions of the Skeletal System