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SKELETAL SYSTEM ANATOMY
The skeletal system in an adult body is made up of 206 individual bones. These bones are
arranged into two major divisions: the axial skeleton and the appendicular skeleton. The axial
skeleton runs along the body’s midline axis and is made up of 80 bones in the following regions:
Skull
Hyoid
Auditory ossicles
Ribs
Sternum
Vertebral column
The appendicular skeleton is made up of 126 bones in the folowing regions:
Upper limbs
Lower limbs
Pelvic girdle
Pectoral (shoulder) girdle
1. Skull
The skull is composed of 22 bones that are fused together except for the mandible. These 21
fused bones are separate in children to allow the skull and brain to grow, but fuse to give added
strength and protection as an adult. The mandible remains as a movable jaw bone and forms
the only movable joint in the skull with the temporal bone. The bones of the superior portion of
the skull are known as the cranium and protect the brain from damage. The bones of the inferior
and anterior portion of the skull are known as facial bones and support the eyes, nose, and
mouth.
2. Hyoid and Auditory Ossicles
The hyoid is a small, U-shaped bone found just inferior to the mandible. The hyoid is the only
bone in the body that does not form a joint with any other bone—it is a floating bone. The
hyoid’s function is to help hold the trachea open and to form a bony connection for the tongue
muscles. The malleus, incus, and stapes—known collectively as the auditory ossicles—are the
smallest bones in the body. Found in a small cavity inside of the temporal bone, they serve to
transmit and amplify sound from the eardrum to the inner ear.
3. Vertebrae
Twenty-six vertebrae form the vertebral column of the human body. They are named by region:
Cervical (neck) - 7 vertebrae
Thoracic (chest) - 12 vertebrae
SKELETAL SYSTEM ANATOMY
The skeletal system in an adult body is made up of 206 individual bones. These bones are
arranged into two major divisions: the axial skeleton and the appendicular skeleton. The axial
skeleton runs along the body’s midline axis and is made up of 80 bones in the following regions:
Skull
Hyoid
Auditory ossicles
Ribs
Sternum
Vertebral column
The appendicular skeleton is made up of 126 bones in the folowing regions:
Upper limbs
Lower limbs
Pelvic girdle
Pectoral (shoulder) girdle
1. Skull
The skull is composed of 22 bones that are fused together except for the mandible. These 21
fused bones are separate in children to allow the skull and brain to grow, but fuse to give added
strength and protection as an adult. The mandible remains as a movable jaw bone and forms
the only movable joint in the skull with the temporal bone. The bones of the superior portion of
the skull are known as the cranium and protect the brain from damage. The bones of the inferior
and anterior portion of the skull are known as facial bones and support the eyes, nose, and
mouth.
2. Hyoid and Auditory Ossicles
The hyoid is a small, U-shaped bone found just inferior to the mandible. The hyoid is the only
bone in the body that does not form a joint with any other bone—it is a floating bone. The
hyoid’s function is to help hold the trachea open and to form a bony connection for the tongue
muscles. The malleus, incus, and stapes—known collectively as the auditory ossicles—are the
smallest bones in the body. Found in a small cavity inside of the temporal bone, they serve to
transmit and amplify sound from the eardrum to the inner ear.
3. Vertebrae
Twenty-six vertebrae form the vertebral column of the human body. They are named by region:
Cervical (neck) - 7 vertebrae
Thoracic (chest) - 12 vertebrae
