THE AXIAL SKELETON
,• The skeletal system forms the rigid internal framework of the body, and
consists of the bones, cartilages, and ligaments.
• Bones provide structural support for the body and protection of intern
organs.
• For adults, there are 206 bones in the skeleton. Younger individuals hav
higher numbers of bones because some bones fuse together during ch
and adolescence to form an adult bone.
• The skeleton is subdivided into two major divisions:
• The axial skeleton, comprised of 80 bones, forms the vertical, central axis of th
and includes all bones of the head, neck, chest, and back.
• The appendicular skeleton, comprised of 126 bones, includes all bones of the u
and lower limbs, plus the bones that attach each limb to the axial skeleton.
,
, • Cartilage provides flexible strength and support for body structures suc
the thoracic cage, the external ear, and the trachea and larynx. At joints
body, cartilage can also unite adjacent bones or provide cushioning betw
them.
• Cartilage is an avascular tissue comprised of extracellular fibers embedd
matrix that contains cells localized in small cavities.
• The amount and kind of extracellular fibers in the matrix varies depend
the type of cartilage, i.e., In heavy weightbearing areas or areas prone
pulling forces, the amount of collagen is greatly increased and the cartil
almost inextensible.
• In areas where weightbearing demands and stress are less, cartilage con
elastic fibers and fewer collagen fibers is common.
• The primary functions of cartilage are to:
• Support soft tissues
• Provide a smooth gliding surface for bone movements at joints
• Facilitate the growth and development of long bones.
,• The skeletal system forms the rigid internal framework of the body, and
consists of the bones, cartilages, and ligaments.
• Bones provide structural support for the body and protection of intern
organs.
• For adults, there are 206 bones in the skeleton. Younger individuals hav
higher numbers of bones because some bones fuse together during ch
and adolescence to form an adult bone.
• The skeleton is subdivided into two major divisions:
• The axial skeleton, comprised of 80 bones, forms the vertical, central axis of th
and includes all bones of the head, neck, chest, and back.
• The appendicular skeleton, comprised of 126 bones, includes all bones of the u
and lower limbs, plus the bones that attach each limb to the axial skeleton.
,
, • Cartilage provides flexible strength and support for body structures suc
the thoracic cage, the external ear, and the trachea and larynx. At joints
body, cartilage can also unite adjacent bones or provide cushioning betw
them.
• Cartilage is an avascular tissue comprised of extracellular fibers embedd
matrix that contains cells localized in small cavities.
• The amount and kind of extracellular fibers in the matrix varies depend
the type of cartilage, i.e., In heavy weightbearing areas or areas prone
pulling forces, the amount of collagen is greatly increased and the cartil
almost inextensible.
• In areas where weightbearing demands and stress are less, cartilage con
elastic fibers and fewer collagen fibers is common.
• The primary functions of cartilage are to:
• Support soft tissues
• Provide a smooth gliding surface for bone movements at joints
• Facilitate the growth and development of long bones.
