1. The Skeleton
Part C 7

2. Seven vertebrae (C1-C7) are the smallest, lightest vertebrae
Cervical Vertebrae
Seven vertebrae (C1-C7) are the smallest, lightest vertebrae
C3-C7 are distinguished with an small oval body, short bifid spinous processes (except C7), and large, triangular vertebral foramina.
Each transverse process contains a transverse foramen
Superior facets directed superoposteriorly foramina
Inferior facets directed inferoanteriorly

3. Cervical Vertebrae: Anatomical characteristics
Movement’s allowed:
Flexion and extension
Rotation (greatest range of movement)
Table 7.2

4. Cervical Vertebrae: The Atlas (C1)
The first two cervical vertebrae, the atlas and the axis have no intervertebral disc between them, and they are highly modified, reflecting their special functions.
The atlas is a ring bone, has no body and no spinous process
It consists of anterior and posterior arches, and two lateral masses
The superior surfaces of lateral masses articulate with the occipital condyles , thus “ They carry the skull, just as Atlas supported the heavens in Greek mythology”. This joint allow you to nod “yes”. The inferior articular surfaces form joints with the axis.

5. Cervical Vertebrae: The Atlas (C1)
Figure 7.16a, b

6. Cervical Vertebrae: The Axis (C2)
The axis has a body, spine, and vertebral arches as do other cervical vertebrae. It is not as specialized as atlas
Unique to the axis is the dens, or odontoid process, which projects superiorly from the body and is cradled in the anterior arch of the atlas
The dens is a pivot for the rotation of the atlas

7. Cervical Vertebrae: The Axis (C2)
Figure 7.16c

8. Cervical Vertebrae: Anatomical view
The spinous p. of C7 is much larger than those of other cervical vertebrae. Because it is visible through the skin C7 can be used as a landmark for counting the vertebrae and it is called “v. prominent”
Figure 7.17a

9. Thoracic Vertebrae
There are twelve vertebrae (T1-T12) all of which articulate with ribs. The first looks much like C7 and the last four like the lumbar vertebral structure. Increase in size from the first to the last
Major markings include: two facets and two demifacets on the heart-shaped body (except T10-T12, have only a single facet), the circular vertebral foramen, transverse processes, and a long spinous process (points sharply downward)
The location of the articulate facets prevents flexion and extension, but allows rotation of this area of the spine

10. Thoracic Vertebrae
With the exception of T11 and T12, the transverse process have facet that articulate with the tubercles of the ribs
Figure 7.17b

11. Lumbar Vertebrae
The five lumbar vertebrae (L1-L5) are located in the small of the back and have an enhanced weight-bearing function. This region receives the most stress
They have short, thick pedicles and laminae, flat hatchet-shaped spinous processes, and a triangular-shaped vertebral foramen
Orientation of articular facets locks the lumbar vertebrae together to provide stability

12. Lumbar Vertebrae
Figure 7.17c

13. Sacrum (triangular) Sacrum
Consists of five fused vertebrae (S1-S5), which shape the posterior wall of the pelvis
It articulates with L5 superiorly, and laterally with the auricular surfaces of the two hip bones to form the sacroiliac joints of the pelvis
Major markings include the sacral promontory, transverse lines, alae, dorsal sacral foramina, sacral canal, and sacral hiatus

14. Coccyx (Tailbone) Coccyx
The coccyx is made up of four (in some cases three to five) fused vertebrae that articulate superiorly with the sacrum

15. Sacrum and Coccyx: Anterior View
Figure 7.18a

16. Sacrum and Coccyx: Posterior View
Figure 7.18b

17. Cervical (3-7) Thoracic Lumbar Body Spinous process Vertebral foramen
Characteristics of Cervical,Thoracic and Lumbar Vertebrae (Table 7.2,and Fig, Pag 222)
Characteristics
Cervical (3-7)
Thoracic
Lumbar
Body
Small, wide side to side
Larger than cervical, heart shaped, bears two costal demifacets
Massive, kidney shaped
Spinous process
Short bifid, projects directly posteriorly
Long, sharp, projects inferiorly
Short, blunt, projects directly posteriorly
Vertebral foramen
Triangular
Circular
Transverse process
Contain foramina
Bear facets for ribs (except T11-T12)
Thin and tapered
Sup. and inf. art. process
Sup facet→ sup-pos
Inf facet → inf-ant
Sup facets→ posterior
Inf. facets → anterior
Sup facet→ posmed
Inf. facet → ant-lat
Movements
Flex and extension, lateral flex, rotation
Rotation, limited lateral flex (ribs), flex & ext prevented
Flex and ext, some lat flexion, rotation prevented

18. Homeostatic Imbalance
Herniated (prolapsed) disc.
Severe or sudden physical trauma to the spine, may result in hernation of one or more discs. A herniated disc (slipped disc) usually involves rupture of the annulus fibrosus followed by protrusion of the spongy nucleus pulposus through the annulus (Fig 7.14). If the protrusion presses on the spinal cord or on spinal nerves exiting from the cord, numbness or excruciating pay result.
Treatments: moderated exercise, massage, heat ther. and painkillers if this fail→ surgery

19. Bony Thorax (Thoracic Cage)
The thoracic cage is composed of the thoracic vertebrae dorsally, the ribs laterally, and the sternum and costal cartilages anteriorly
Functions
Forms a protective cage around the heart, lungs, and great blood vessels
Supports the shoulder girdles and upper limbs
Provides attachment for many neck, back, chest, and shoulder muscles
Uses intercostal muscles to lift and depress the thorax during breathing

20. Bony Thorax (Thoracic Cage)
Figure 7.19a

21. Bony Thorax (Thoracic Cage)
Figure 7.19b

22. Sternum (Breastbone)
A dagger-shaped, flat bone that lies in the anterior midline of the thorax
Results from the fusion of three bones – the superior manubrium, the body, and the inferior xiphoid process
Anatomical landmarks include the jugular (suprasternal) notch, the sternal angle, and the xiphisternal joint

23. All ribs attach posteriorly to the thoracic vertebrae
There are twelve pair of ribs forming the flaring sides of the thoracic cage
All ribs attach posteriorly to the thoracic vertebrae
The superior 7 pair (true, or vertebrosternal ribs) attach directly to the sternum via costal cartilages
Ribs 8-10 (false, or vertebrocondral ribs) attach indirectly to the sternum via costal cartilage
Ribs (floating, or vertebral ribs) have no anterior attachment

24. Ribs
Figure 7.19a

25. Structure of a Typical True Rib
Bowed, flat bone consisting of a head, neck, tubercle, and shaft
Figure 7.20

26. Appendicular Skeleton
Although the bones of upper and lower limbs differ in their functions and mobility, they have the same fundamental plan: each limb is composed of three major segments connected by movable joints.
The appendicular skeleton is made up of the bones of the limbs and their girdles
Pectoral girdles attach the upper limbs to the body trunk
Pelvic girdle secures the lower limbs

27. Pectoral Girdles (Shoulder Girdles)
The pectoral girdles consist of the anterior clavicles and the posterior scapulae
They attach the upper limbs to the axial skeleton in a manner that allows for maximum movement
They provide attachment points for muscles that move the upper limbs

28. Pectoral Girdles (Shoulder Girdles)
Figure 7.22a

29. Clavicles (Collarbones) “ Little keys”
The clavicles are slender, doubly curved long bones lying across the superior thorax
The acromial (lateral) end articulates with the scapula, and the sternal (medial) end articulates with the sternum
They provide attachment points for numerous muscles, and act as braces to hold the scapulae and arms out laterally away from the body

30. Clavicles (Collarbones)
Each clavicle is cone shaped at its medial sternal end, which attaches to the sternal manubrium, and flattened at its lateral acromail end in which articulate with scapula
Figure 7.22b, c

31. Scapulae (Shoulder Blades)
The scapulae are thin triangular, flat bones lying on the dorsal surface of the rib cage, between the second and seventh ribs
Scapulae have three borders and three angles:
1.- superior (shortest, sharpest), 2.- medial (borders parallels to the vertebra col, 3.- lateral or axillary (were articulates with humerus)
Major markings include the suprascapular notch, the supraspinous and infraspinous fossae, the spine, the acromion, and the coracoid process

32. Scapulae (Shoulder Blades)
Figure 7.22d, e