Chapter 7

1. Chapter 7 The Skeleton J.F. Thompson, Ph.D. & J.R. Schiller, Ph.D. & G. Pitts, Ph.D.

2. Divisions of the Skeleton • Axial skeleton • long axis of the body • skull, vertebral column, rib cage • Appendicular skeleton • appendages and connections • upper, lower limbs, pelvic, pectoral girdles Know the Features Outlined in Your Lab Guide.

3. The Skeleton Know the Features Outlined in Your Lab Guide.

4. The Adult Skeleton

5. The Fetal Skeleton

6. The Fetal Skull Intramembranous ossification with sutures fusing late so the skull bones can expand to accommodate significant brain growth.

7. The Fetal Skull Intramembranous ossification with sutures fusing late so the skull bones can expand to accommodate significant brain growth.

8. Body Part Growth Rates Trunk and limbs develop more slowly than cranium and face.

9. Human Body Form Varies Geographically Humans adapted to cold climates often have thick trunks and shorter limbs; those adapted to warm climates tend to be taller and slimmer. • Inuit from the Arctic (under five feet tall). • Nilote of near equatorial Africa (over six feet tall).

10. Modern Human Regional Variation African European-SW Asian East Asian Australian

11. Humans Are Bipedal Apes Apes are large tailless omnivorous primates with relatively large brains and complex social behaviors. Apes evolved in Africa and Asia and most live in moist tropical forests.

12. The Living Apes Anatomical striking resemblance Asia Africa now global

13. Comparison of Human and Ape Skeletons Non-human apes are quadrupeds Human – Gorilla – Chimpanzee – Orangutan - Gibbon

14. Comparison of Human and Ape Skeletons The differences in the skeletons of the apes are primarily differences in proportions of bones reflecting different styles of locomotion, different diets, and intelligence.

15. The Major Morphological Trends • Larger brain; taller, flatter face; smaller jaws and teeth, and structural adaptations for making the sounds of speech.

16. Most of the differences between Humans and Apes are adaptations to walking bipedally. foramen magnum spinal double curvature pelvic architecture femur angle weight-bearing knee double arched foot

17. Brief Survey of the Human Skeleton We emphasize the changes between bipedal humans and the other quadrupedal apes. The shift to bipedalism, while advantageous to human success, also has many negative consequences. Many of these differences have clinical significance.

18. Anatomy of the Lateral Aspect of the Skull Know the Features Outlined in Your Lab Guide.

19. Anatomy of the Anterior Aspect of the Skull diastemas interlocking canines The human Canine Teeth are especially reduced compared to Apes to Usually no diastemas (gaps) between teeth. permit rotational chewing.

20. Dentition Chimpanzee incisors tip forward to grasp and mash soft fruit Reduced human canines aligned with the incisors form a cutting blade for tougher plant and animal foods.

21. Dentition Diastemas develop as the jaws of an ape grow anteriorly

22. Anatomy of the Lateral Internal Aspect of the Skull Know the Features Outlined in Your Lab Guide. The Forehead is taller. The human Cranium is much enlarged compared to apes. chimpanzee The human face is much Flatter.

23. Anatomy of the Inferior Portion of the Skull The Dental Arch is broader and more rounded than in apes chimpanzee mandible →

24. Anatomy of the Lateral Aspect of the Skull The human Palate is arched which gives greater variety to tongue shapes to articulate speech.

25. Changes in the Palate and Dentition Note arches, canine sizes, diastemas, incisor sizes and molar sizes.

26. Anatomy of the Inferior Portion of the Skull Know the Features Outlined in Your Lab Guide. The Foramen Magnum is centered under the expanded brain, compared to apes, for erect posture.

27. Detailed Anatomy of Some Isolated Facial Bones Humans have a distinct chin and the attachment of the tongue behind the chin allows for more varied tongue movements necessary to articulate speech sounds. chin chimpanzee mandible

28. Compare Forehead height, flatness of face, prominence of chin; note the differences are less pronounced in the infants.

29. Figure 7.10A Special anatomical characteristics of the nasal cavity Why Have Air-Filled Sinuses in the Skull?

30. Paranasal Sinuses: Anterior Aspect Probably Vestigial Structures – sites for additional Olfactory Epithelium in ancestral species. As resonating chambers, give distinct timbre to each human voice.

31. The Vertebral Column Note the Double Curvature of the Spine. It is an Adaptation for Upright Posture. Apes (and human neonates) have a single curve. Know the Features Outlined in Your Lab Guide.

32. Note the Complex Set of Ligaments And the Intervertebral Discs

33. Posterolateral Views of Articulated Vertebrae Much of the rotation of the head occurs at the joint between the atlas (C1) and dens of the axis (C2).

34. Intervertebral Disc surrounded by the meninges normal degenerate fibrocartilage gelatinous remnant of the notochord

35. Regional Characteristics of Cervical, Thoracic, and Lumbar Vertebrae Key Differences Among Vertebral Types: For Blood Vessels Size Of Body Facets for Rib to Attach. No Facets for Rib to Attach

36. The Bony Thorax Like other apes, Humans have a broad but Shallow rib cage, an adaptation to Brachiation

37. The Bony Thorax CPR: The position of the heart beneath the sternum permits the CPR technique to pump blood when the heart has ceased to pump on its own.

38. Bones of the Appendicular Skeleton: Pectoral Girdle and Upper Limb Know the Features Outlined in Your Lab Guide. * * Greater Opposability of the thumb is the main difference between the human and the ape arm.

39. Forelimb: the pectoral girdle is adapted for braciation in apes and humans * Greater Opposability of the Thumb is the Main Difference Between the Human and the Ape Arm. *

40. Manual Dexterity Compare relative finger lengths and note the opposability of the thumbs.

41. The Size of the Angle of the Pubic Arch and of the Greater Sciatic Notch are the Best Gender Markers.

42. Humans and Human AncestorsAre Fundamentally Bipedal Apes. Curved femurs allow feet to be placed together; a larger hip joint can bear more body weight

43. Bones of the Right Foot Compared to the ape’s foot, the human foot is entirely changed and adapted to Bipedal Locomotion; there is no opposability of the big toe.

44. Arches of the Foot The Double Arch Design is an Adaptation to Bipedal Locomotion, walking and running.

45. Comparison of Hominoid Pelves and Feet Changes accommodate muscle attachments for bipedal locomotion.

46. Hip Mechanics and Locomotion

48. Hip Mechanics and Birth Canal Compare the Bonobo and Human females. The human waist seems narrow because the hip (coxal) bones have grown wider and the gluteal muscles have grown larger. An Australopithecine would be intermediate in architecture, but fully bipedal and a bit more efficient at walking!

49. Ape and Hominid Skeletons • Respectively, the backbone joins the back of the skull in apes versus the bottom. • The ape backbone is arched while the hominid is S-shaped. • The arms are long in both, but shorter than hindlimbs in the ape compared to the hominid. • The hips are long or bowl-shaped and the femur (upper leg bone) is angled out or in.

50. Comparison of Ape and Human Posture