1. The Skeletal System

2. The Axial Skeleton

3. The Axial Skeleton Forms the longitudinal part of the body
Divided into three parts
Skull
Vertebral column
Bony thorax

4. The Skull Two sets of bones
Cranium– encloses and protects the brain, and its surface provides attachments for muscles that make chewing and head movement possible.
8 bones in the cranium (PEST OF 6)
Frontal (1)
Parietal (2)
Occipital (1)
Temporal (2)
Sphenoid (1)
Ethmoid (1)
PEST OF 6

5. The Skull (Continued)
Facial bones -14 Facial bones (Virgil Can Not Make My Pet Zebra Laugh)
Maxillary (2)
Palatine (2)
Zygomatic (2)
Lacrimal (2)
Nasal (2)
Vomer (1)
Inferior nasal conchae (2)
Mandible

6. The Skull (Continued) Bones are joined by sutures (Major Sutures)
Squamous sutures - between parietal and temporal bones on each side of skull
Coronal suture - between parietal bones and frontal bone
Lambdoidal suture - between parietal bones and occipital bone
Sagittal suture - between right and left parietal bones
Only the mandible is attached by a freely movable joint – temporomandibular joint

7. Skull – Lateral View

8. Skull – Anterior View

9. Skull, Superior View

10. Skull, Inferior View

11. The Hyoid Bone
The only bone that does not articulate with another bone
Serves as a moveable base for the tongue

12. The Vertebral Column Transmits weight of trunk to lower limbs
Surrounds and protects spinal cord
Flexible curved structure containing 26 irregular bones (vertebrae)
Cervical vertebrae (7)—vertebrae of the neck
Thoracic vertebrae (12)—vertebrae of the thoracic cage
Lumbar vertebrae (5)—vertebra of the lower back
Sacrum—bone inferior to the lumbar vertebrae
Coccyx—terminus of vertebral column

13. The Vertebral Column Vertebrae separated by intervertebral discs
The spine has a normal curvature
Each vertebrae is given a name according to its location

14. Structure of a Typical Vertebrae
Seven processes per vertebra:
Spinous process—projects posteriorly
Transverse processes (2) - project laterally
Superior articular processes (2) -protrude superiorly inferiorly
Inferior articular processes (2) -protrude inferiorly

15. Structure of a Typical Vertebrae

16. Cervical Vertebrae C1 to C7: smallest, lightest vertebrae
C3 to C7 share the following features
Oval body
Spinous processes are bifurcated (except C7)
Large, triangular vertebral foramen
Transverse foramen in each transverse process

17. Cervical Vertebrae

18. Cervical Vertebrae C1 (atlas) and C2 (axis) have unique features
Atlas (C1)
No body or spinous process
Consists of anterior and posterior arches, and two lateral masses
Superior surfaces of lateral masses articulate with the occipital condyles
Axis (C2)
Dens projects superiorly into the anterior arch of the atlas
Dens is a pivot for the rotation of the atlas

19. Cervical Vertebrae

20. (a) Cervical vertebrae
Dens of axis
Transverse ligament
of atlas
C1 (atlas)
C2 (axis) C3
Inferior articular
process
Bifid spinous
process
Transverse processes
C7 (vertebra
prominens)
(a) Cervical vertebrae
Figure 7.20a

21. Thoracic Vertebrae T1 to T12 All articulate with ribs at facets
Long spinous process
Location of articular facets allows rotation of this area of spine

22. Thoracic Vertebrae

23. (b) Thoracic vertebrae
Superior articular
process
Transverse
process
Transverse
costal facet (for
tubercle of rib)
Intervertebral
disc
Body
Inferior costal
facet (for head
of rib)
Spinous
process
Inferior articular
process
(b) Thoracic vertebrae
Figure 7.20b

24. Lumbar Vertebrae L1 to L5 Massive bodies for weight bearing
Orientation of articular facets locks lumbar vertebrae together so as to prevent rotation

25. Lumbar Vertebrae

26. Superior articular process Transverse Body process Intervertebral disc
Inferior
articular
process
Spinous
process
(c) Lumbar vertebrae
Figure 7.20c

27. Sacrum and coccyx Sacrum 5 fused vertebrae (S1–S5)
Forms posterior wall of pelvis
Articulates with L5 superiorly, and with auricular surfaces of the hip bones laterally
Coccyx
Tailbone
3–5 fused vertebrae
Articulates superiorly with sacrum

28. Sacrum and Coccyx

29. The Bony Thorax Composed of Thoracic vertebrae Sternum
Ribs and their costal cartilages
Functions
Protects vital organs of thoracic cavity
Supports shoulder girdle and upper limbs
Provides attachment sites for many muscles, including intercostal muscles used during breathing

30. Sternum (Breastbone) Three fused bones Manubrium
Articulates with clavicles and ribs 1 and 2
Body
Articulates with costal cartilages of ribs 2 through 7
Xiphoid process
Site of muscle attachment
Not ossified until ~ age 40

31. Ribs and Their Attachments
12 pairs
All attach posteriorly to thoracic vertebrae
Pairs 1 through 7
True ribs
Attach directly to the sternum by individual costal cartilages

32. Ribs and Their Attachments
Pairs 8 through12
False ribs
Pairs 8–10
Attach indirectly to sternum by joining costal cartilage of rib above
Pairs 11–12
No attachment to sternum

33. The Bony Thorax