1. Skeletal System: the spine
Learning Target #5

2. Vertebral Column Adults have 26 total vertebrae, found in 5 divisions:
Cervical = 7 in the neck (C1 – C7)
Thoracic = 12 in the chest (T1 – T12)
Lumbar = 5 in the lower back (L1 – L5)
Sacrum = 5 fused together
Coccyx = 4 fused together (also called the tailbone)

3. Curvatures of the Spine
The S-shape (anterior-posterior curvatures) of the adult spine help to…
Prevent shock to the head in walking and running
Makes the trunk of the body flexible
A developing fetus only has one concave curve
Adults have 4 curves:
Cervical and lumbar = convex
Thoracic and sacral = concave

4. Curvatures of the Spine
Cervical (7)
(concave)
Thoracic (12)
(convex)
Lumbar (5)
(concave)
Sacrum (5)
(concave)
Coccyx (4)

5. Basic Vertebral Structure
Body = thick, disc-shaped portion; bears most of the weight
Vertebral arch = extends behind the body
Vertebral foramen = space between the body and the vertebral arch
Processes = things that stick off the vertebrae
Transverse process = extend laterally (2)
Spinous process = extend behind and down
Lamina = portion of arch that connects the processes

6. Basic Vertebral Structure
Spinous Process
Lamina
Transverse Process
Vertebral Foramen
Body

7. Intervertebral Discs Made of fibrocartilage Functions:
Absorb shock
Protect the spinal cord
Allow for flexibility of the spine
Each disc has two major regions: a central gelatinous region that behaves like a fluid and an outer ring of collagen fibers that stabilizes the disc

8. How do we move our heads? Atlas = C1 vertebrae Axis = C2 vertebrae
Supports the head
Lacks a body and a spinous process
Contains superior articular facets that articulate with the occipital condyles  allows us to nod our heads
Axis = C2 vertebrae
Does not have a body
Odontoid process projects upward through the ring of the atlas  makes a pivot on which the head can rotate from side to side

9. How do we move our heads?
Odontoid process

10. Irregular Curvatures of the Spine
Scoliosis = lateral curve
80% of cases have no known cause, but can be genetic
Kyphosis = exaggerated thoracic curve
Caused by osteoporosis and disc degeneration
Lordosis = exaggerated lumbar curve
Also caused by osteoporosis and associated with obesity