the skeleton. two divisions axial appendicular axial skeleton
The “axis” of the Body
• 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
• 22 bones– 8 cranial– 14 facial
• Seven additional bones in the skull– 6 auditory ossicles– Hyoid bone
• Suspended below the skull by ligaments
• Muscle base for the larynx (voice box)
• Supports and positions the larynx
• 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
• 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
• For the three types of vertebrae there are different distinguishing features
• The openingsof the vertebrae(foramen) form thevertebral canalwhich enclosethe spinal cord
• 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
• 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
Superior articular facet
• 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
Superior articular facet Foramen
Lumber Vertebrae• There are 5 lumbar vertebrae located in the
• Receive the most stress and are the weight-bearing portion of the back.
• Allow movements such as flexion and extensionand some lateral flexion.
Lumbar Vertebrae Anatomy
Superior articular facet
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
• 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
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
intervertebral disc x ray