The Skeleton
Two Divisions
• Axial
• Appendicular
Axial Skeleton
The “axis” of the Body
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Skull
Inner ear bones
Hyoid Bone
Rib cage
Vertebral column
Axial Skeleton Functions
• Framework for supporting and protecting
organ systems in dorsal and ventral body
cavities
• Surface area for muscle attachment
– Head, neck and trunk stability and movement
– Respiratory movement
– Stabilize/position appendicular skeleton
Skull
• Protect Brain
• Support sense organs
– Vision
– Hearing
– Balance
– Olfaction
– gustation
Skull
• 22 bones
– 8 cranial
– 14 facial
• Seven additional
bones in the skull
– 6 auditory ossicles
– Hyoid bone
Hyoid Bone
• Suspended below the skull by ligaments
• Muscle base for the larynx (voice box)
• Supports and positions the larynx
Vertebral Column
• Spine is 26 bones
– 24 vertebrae
– Saccrum
– Coccyx
Vertebral Column
• Vertebrae are in regions
– Cervical (C1 – C7): C1 = atlas; C2 = axis
– Thoracic (T1 – T12)
• Articulate with ribs
– Lumbar (L1 – L5)
• Total length in average adult is 28 inches
Intervertebral Disc
• Fibrocartilage disc that lies between two
adjoining vertebrae
• Not found in sacrum
or coccyx
• “Shock absorbers”
• Act as ligaments that hold the
vertebrae of the spine together and
as cartilaginous joints that allow for
slight mobility in the spine.
• Allow for movement at the waist as
they act as a pivot point and allow the
lumbar spine to bend, rotate, and
twist
Vertebrae Anatomy
• For the three types of vertebrae there are
different distinguishing features
• The openings
of the vertebrae
(foramen) form the
vertebral canal
which enclose
the spinal cord
Vertebrae Anatomy
• Vertebral foramen: opening
• Vertebral arch: posterior margin of
foramen
• Transverse process: site for muscle
attachment
• Spinous process: Bump down your back
• Body: weight-bearing portion
• Lamina: roof of vertebral arch
• Pedicle: walls of vertebral arch
Cervical Vertebrae
• There are seven cervical vertebrae which are
located in the neck.
• They are the smallest,
and lightest vertebrae
of the vertebral column.
Cervical Vertebrae Anatomy
Spinous
Process
Superior
articular facet
Lamina
Foramen
Pedicle
Transverse
Process
Body
Thoracic Vertebrae
• The rib cage of the chest is
attached to the thoracic
spine at each level.
• Gives a great deal of
stability and support to the
upper body.
• Limits the back's movement
at the chest level.
Thoracic Vertebrae Anatomy
Spinous
Process
Transverse
Process
Lamina
Superior
articular facet
Foramen
Pedicle
Body
Lumber Vertebrae
• There are 5 lumbar vertebrae located in the
lower back.
• Receive the most stress and are the weightbearing portion of the back.
• Allow movements such
as flexion and extension
and some lateral flexion.
Lumbar Vertebrae Anatomy
Spinous
Process
Superior
articular facet
Lamina
Foramen
Pedicle
Transverse
Process
Body
Sacrum and Coccyx
• Sacrum: five fused vertebrae
– Protects reproductive and digestive organs
– Attaches axial to appendicular skeleton
– Extensive muscle attachment
• Coccyx: 3-5 fused vertebrae
– Attachment site for muscle that closes anal
opening
Spinal Curves
• Curved to allow for weight distribution
• 2 primary curves: appear in late fetal
development
– Thoracic
– Sacral
• 2 secondary curves: occur months after
birth
– Cervical
– lumbar
Spinal Curves
Secondary Curve
Primary Curve
Secondary Curve
Primary Curve
Chest Bones (Thorax)
• Thoracic Vertebrae
• Ribs
• Sternum
Ribs and Sternum
• 12 pairs of ribs
• 7 pairs of “true ribs”
– Reach the anterior body wall and connect to
the sternum by separate cartilage (costal
cartilage)
• 8-12 are “false ribs”
– Do not attach directly to the sternum
– Costal cartilage of 8-10 fuses with 7
• Last Two pairs = “floating ribs”
– No sternum connection
Sternum
• Manubrium: articulates
with the clavicle
• Body
• Xiphoid process
intervertebral disc x ray
• http://www.chirogeek.com/000_disc_anato
my.htm
• http://spanky.thehawkeye.com/features/sur
gery/index.html