Skeletal System
Divisions of the Skeleton
• Axial skeleton consists of 74 bones that
form the upright axis of the body and 6
tiny middle ear bones
• Appendicular skeleton consists of 126
bones that form the shoulder girdles,
arms, wrists, and hands and the hip
girdles, legs, ankles and feet.
Axial Skeleton
The Skull
• 28 irregularly shaped bones
• Two major divisions
– Cranium (brain case)
• 8 bones
• All cranial bones are unpaired except for the parietal and
temporal bones
– Face
• 14 bones
• All of the face bones are paired except the mandible and
vomer
Hyoid Bone
• Single U-shaped
bone in neck
• Just above the
voice box
• Only bone in the
body that does not
articulate with any
other bones
Vertebral Column
• Longitudinal axis of the
skeleton
• 24 vertebrae, sacrum and
coccyx
• Forward, backward and
sideways movement
Vertebral Column
• 7 Cervical vertebrae (neck)
• 12 Thoracic vertebrae
• 5 Lumbar vertebrae (small of the back)
• Sacrum (5 separate vertebrae that are
fused in adults)
• Coccyx (4 or 5 fused vertebrae)
Atlas and Axis
Axis
Atlas
• First cervical
vertebrae
• Supports the skull
• Second cervical
vertebrae
• Dens joins axis to
atlas
•Atlas and axis allow
the head to turn from
side to side
Sternum
• Consists of three
bones
– Manubrium
– Body
– Xiphoid Process
Ribs
• Protect the vital organs of the torso
• Ribs one through seven connect directly
to the sternum (true ribs)
• Ribs eight through 10 connect to costal
cartilage (false ribs)
• Ribs 11 and 12 only connect to the back
(floating ribs)
Ribs and Sternum
Appendicular Skeleton
Shoulder Girdle (Pectoral Girdle)
Bones of the Arm (Anterior View)
Bones of the Arm (Posterior View)
Bones of the
Hand
The Pelvic Girdle
• Supports the trunk and attaches the
lower extremities
• In early life each coxal bone is made up
of three separate bones which later fuse
to form one large bone
– Ilium
– Ischium
– Pubis
Right Coxal Bone
The Female
Pelvis
• Male Pelvis is deep
and funnel shaped
with a narrow
subpubic angle
• Female pelvis is
shallow, broad, and
flaring with a wider
subpubic angle
The Foot
Bone Fractures
• Partial or complete break in the
continuity of a bone
• Open fracture (compound fracture) the
broken bone projects through the skin
• Closed fracture (simple fracture) does
not break the skin
Bone Fractures
Abnormal Spine Curvatures
Curvatures
• a. Lordosis – “sway back”
• b. Kyphosis – “rounded back”
• c. Scoliosis - “ lateral – sideways”
Spine Curvature
• Convex through the thoracic region
• Concave through the lumbar region
• scoliosis