1. The Axial Skeleton Forms the longitudinal axis of the body
Divided into three parts
Skull- protects the brain
Vertebral column – protects the spinal column
Bony thorax-protects thoracic cavity (heart & lungs)

2. The Axial Skeleton
Figure 5.6a

3. The Axial Skeleton
Figure 5.6b

4. The Skull Two sets of bones
Cranium
Facial bones
Bones are joined by sutures- interlocking joints; immovable joints that connec bones of skull
Only the mandible is attached by a freely movable joint

5. Major Sutures of the skull
Bones they connect
Sagittal
2 parietal bones
Coronal
Parietals meet frontal bone
Squamous
Temporal meets parietal
Lamboid
Occipital meets parietal

6. Bones of the Cranium Frontal Sphenoid Ethmoid Right Parietal
Left Parietal
Right Temporal
Left Temporal
Occipital

7. Facial Bones Maxillae Palantine Zygomatic Lacrimal Nasal Vomer
Inferior Nasal Conchae
Mandible

8. Human Skull, Lateral View
Bone forming anterior cranium
Bone pair united by sagittal suture
Has greater and lesser wings
Site of external auditory meatus
Superior and inferior nasal conchae are part of this bone
Its “holey plate allows olfactory fibers to pass
Allows tear ducts to pass
Boney skeleton of the nose
Cheek bone
Forms most of hard palate
Upper jaw
Figure 5.7

9. Human Skull, Superior View
Has greater and lesser wings
Contains a “saddle” that houses the pituitary gland
**forms a plateau across the width of the skull
Figure 5.8

10. Human Skull, Inferior View
Forms most of hard palate
Posterior roof of mouth
Inferior part of nasal septum
Site of jugular foramen and carotid canal
Its oval-shaped protrusions articulate with the atlas
Spinal cord passes through opening
Figure 5.9

11. Human Skull, Anterior View
Sagittal suture
Contains a paranasal sinus
Contains a paranasal sinus
Squamous sutrue
(Greater wing)
Contains a paranasal sinus
Contain alveoli bearing teeth
Facial bone that contains a sinus
Inferior part of nasal septum
Forms the chin
Contain alveoli bearing teeth
Figure 5.11

12. Paranasal Sinuses
Hollow portions of bones surrounding the nasal cavity
Functions of paranasal sinuses
Lighten the skull
Give resonance and amplification to voice

13. Paranasal Sinuses
Figure 5.10a

14. Paranasal Sinuses
Figure 5.10b

15. orbit
Seven skull bones form the orbit: frontal, sphenoid, ethmoid, lacrimal, maxilla, palatine, and zygomatic

16. Ear bones
The middle ear contains three tiny bones known as the ossicles: malleus, incus, and stapes. The ossicles were given their Latin names for their distinctive shapes; they are also referred to as the hammer, anvil, and stirrup, respectively. The ossicles directly couple sound energy from the ear drum to the oval window of the cochlea. While the stapes is present in all tetrapods, the malleus and incus evolved from lower and upper jaw bones present in reptiles.

17. The Hyoid Bone
*not really a skull bone
The only bone that does not articulate with another bone
Serves as a moveable base for the tongue
Aids in swallowing and speech

18. The Hyoid Bone
Figure 5.12

19. The Fetal Skull aka BIG HEAD
The fetal skull is large compared to the infant’s total body length
Fetal skull is 1/4th total body length
Adult skull is only 1/8th total body length
Adolescence
Epiphyseal plates become ossified and long bone growth ends

20. The Fetal Skull
Figure 5.13a

21. The Fetal Skull Face is smaller in proportion to cranium Figure 5.13b
Growth (ossification) center:
conical projection on some cranial bones
Face is smaller in proportion to cranium
Figure 5.13b

22. Developmental Aspects of the Skeletal System
Fontanels—fibrous membranes connecting the cranial bones
Allows skull to be compressed during birth and allows for brain growth during late fetal life
At birth, the skull bones are incomplete
Bones are joined by fibrous membranes called fontanels
Fontanels are completely replaced with bone within two years after birth

23. Skeletal Changes Throughout Life
Fetus
Long bones are formed of hyaline cartilage
Flat bones begin as fibrous membranes
Flat and long bone models are converted to bone
Birth
Fontanels remain until around age 2
Ossification Centers in a 12-week-old Fetus

24. Skeletal Changes Throughout Life
Size of cranium in relationship to body
2 years old—skull is larger in proportion to the body compared to that of an adult
8 or 9 years old—skull is near adult size and proportion
Between ages 6 and 11, the face grows out from the skull

25. Skeletal Changes Throughout Life
Between ages 6 and 11, the face grows out from the skull
Figure 5.33a

26. The Vertebral Column
Each vertebrae is given a name according to its location
There are 24 single vertebral bones separated by intervertebral discs - made up of fibrocartilage
Seven cervical vertebrae are in the neck
Twelve thoracic vertebrae are in the chest region
Five lumbar vertebrae are associated with the lower back
Herniated disc= a slipped disc; protruding cartilage from vertebra. Causes pain and numbness

27. The Vertebral Column Nine vertebrae fuse to form two composite bones
Sacrum- five components; fused
Coccyx- tail bone

28. The Vertebral Column
Figure 5.14

29. The Vertebral Column The spine has a normal curvature
Primary curvatures are the spinal curvatures of the thoracic and sacral regions…like a c
Present from birth
Secondary curvatures are the spinal curvatures of the cervical and lumbar regions…like an s
Develop after birth

30. The Vertebral Column C shaped spine
Figure 5.15

31. The Vertebral Column Abnormal spinal curvatures (scoliosis and lordosis) are often congenital
Figure 5.16

32. A Typical Vertebrae, Superior View
Figure 5.17

33. Regional Characteristics of Vertebrae
Atlas lacks a body
Pivots with C2
Axis articulates with the occipital condyles
Figure 5.18a

34. Regional Characteristics of Vertebrae
Forked spinous process
Figure 5.18b

35. Regional Characteristics of Vertebrae
Bear facets for articulation with ribs; form part of the bony thoracic cage
Figure 5.18c

36. Regional Characteristics of Vertebrae
Vertebrae with blocklike body and short stout spinous process
Figure 5.18d

37. Sacrum and Coccyx Sacrum Coccyx Formed by the fusion of five vertebrae
Forms a joint with the hip bone
Coccyx
Formed from the fusion of three to five vertebrae
“Tailbone,” or remnant of a tail that other vertebrates have

38. Sacrum and Coccyx
Figure 5.19

39. The Bony Thorax Forms a cage to protect major organs-cone shaped
Consists of three parts
Sternum
Ribs
True ribs (pairs 1–7)
False ribs (pairs 8–12)
Floating ribs (pairs 11–12)
Thoracic vertebrae

40. The Bony Thorax
Figure 5.20a

41. Kyphosis

42. Scoliosis

43. Lordosis
Lordosis is a condition that causes the spine to curve towards the body at an exaggerated rate. This curvature makes the individual appear to have a swayback.
Signs of lordosis include a prominent protrusion of the buttocks. An inflexible spine in the affected area signals a severe case of lordosis. Individuals with lordosis and a flexible spine may require no treatment beyond physical therapy. Treatment for lordosis with an inflexible spine includes using a brace and possible surgery.