THE AXIAL SKELETON
HBT 2107
Anatomy and physiology
,• 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 internal
organs.
• For adults, there are 206 bones in the skeleton. Younger individuals
have higher numbers of bones because some bones fuse together
during childhood 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 the
body and includes all bones of the head, neck, chest, and back.
• The appendicular skeleton, comprised of 126 bones, includes all bones of the
upper and lower limbs, plus the bones that attach each limb to the axial skeleton.
,
, • Cartilage provides flexible strength and support for body structures such as
the thoracic cage, the external ear, and the trachea and larynx. At joints of the
body, cartilage can also unite adjacent bones or provide cushioning between
them.
• Cartilage is an avascular tissue comprised of extracellular fibers embedded in
a matrix that contains cells localized in small cavities.
• The amount and kind of extracellular fibers in the matrix varies depending on
the type of cartilage, i.e., In heavy weightbearing areas or areas prone to
pulling forces, the amount of collagen is greatly increased and the cartilage is
almost inextensible.
• In areas where weightbearing demands and stress are less, cartilage
containing 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.
HBT 2107
Anatomy and physiology
,• 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 internal
organs.
• For adults, there are 206 bones in the skeleton. Younger individuals
have higher numbers of bones because some bones fuse together
during childhood 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 the
body and includes all bones of the head, neck, chest, and back.
• The appendicular skeleton, comprised of 126 bones, includes all bones of the
upper and lower limbs, plus the bones that attach each limb to the axial skeleton.
,
, • Cartilage provides flexible strength and support for body structures such as
the thoracic cage, the external ear, and the trachea and larynx. At joints of the
body, cartilage can also unite adjacent bones or provide cushioning between
them.
• Cartilage is an avascular tissue comprised of extracellular fibers embedded in
a matrix that contains cells localized in small cavities.
• The amount and kind of extracellular fibers in the matrix varies depending on
the type of cartilage, i.e., In heavy weightbearing areas or areas prone to
pulling forces, the amount of collagen is greatly increased and the cartilage is
almost inextensible.
• In areas where weightbearing demands and stress are less, cartilage
containing 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.
