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Chapter 7: The Axial Skeleton 1. Human Skeleton Human Skeleton = 206 Bones 1.Axial Skeleton: -longitudinal axis -80 bones 2.Appendicular Skeleton: -limbs.

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Presentation on theme: "Chapter 7: The Axial Skeleton 1. Human Skeleton Human Skeleton = 206 Bones 1.Axial Skeleton: -longitudinal axis -80 bones 2.Appendicular Skeleton: -limbs."— Presentation transcript:

1 Chapter 7: The Axial Skeleton 1

2 Human Skeleton Human Skeleton = 206 Bones 1.Axial Skeleton: -longitudinal axis -80 bones 2.Appendicular Skeleton: -limbs -126 bones 2

3 The Axial Skeleton Figure 7–1a 3

4 Axial Skeleton 4

5 Appendicular Skeleton 5

6 Axial Skeleton Function 1.Support and protect organs in dorsal and ventral body cavities 2.Provide surface area for muscle attachment: A.Adjust position of head, neck, & trunk B.Perform respiratory movements C.Stabilize appendicular skeleton 6

7 Bones of the Axial Skeleton The skull: 22 bones –8 cranial bones: form the braincase or cranium –14 facial bones: protect and support entrances to digestive and respiratory tracts Skull bones interconnect at immovable joints called sutures –Dense fibrous CT 7

8 Skull: 22 Bones 8

9 Cranial Bones Enclose the cranial cavity Which contains the brain: –and its fluids, blood vessels, nerves, and membranes 9

10 The Facial Bones Superficial facial bones: –for muscle attachment –Maxillary, Lacrimal, Nasal, Zygomatic, and Mandible Deep facial bones: –separate the oral and nasal cavities –form the nasal septum –Palatine bones, Inferior nasal conchae, and Vomer 10

11 The Maxillary Bones The largest facial bones Figure 7–10a 11

12 Functions of the Maxillary Bones Support upper teeth Form inferior orbital rim Form lateral margins of external nares Form upper jaw and hard palate Contain maxillary sinuses (largest sinuses) 12

13 The Palatine Bones Figure 7–10b,c 13

14 Functions of the Palatine Bones Form the posterior portion of the hard palate Contribute to the floors of the orbits 14

15 The structures and functions of the nasal complex. 15

16 The Small Bones of the Face Figure 7–11 16

17 Functions of the Nasal Bones Nasal Bones –Support the bridge of the nose –Connect to cartilages of the distal part of the nose (external nares) Vomer –Forms the inferior portion of the bony nasal septum Inferior Nasal Conchae –To create air turbulence in the nasal cavity –To increase the epithelial surface area –To warm and humidify inhaled air 17

18 The Mandible Forms the lower jaw Figure 7–12a,b 18

19 The Hyoid Bone Function: –Supports the larynx –Attaches muscles of the larynx, pharynx, and tongue Figure 7–12c 19

20 Marks of the Hyoid Bone Greater horns (greater cornua): –support larynx –attach muscles of the tongue Lesser horns (lesser cornua): –attach stylohyoid ligaments –support hyoid and larynx 20

21 Skull Four major sutures: 1.Lambdoid: - separates occipital bone from parietal bones 2.Corona: - separates frontal bone from parietal bones 3.Sagittal: - separates parietal bones 4.Squamous: - (2) separates temporal bone from parietal bone 21

22 Sutures The immovable joints of the skull Figure 7–3a, b 22

23 Sutures Figure 7–3c 23

24 Sutures Figure 7–3d, e 24

25 The Orbital Complex Portions of 7 cranial and facial bones Figure 7–13 25

26 The Orbital Complex Forms the eye sockets (orbits): –frontal bone (roof) –maxillary bone (floor) –maxillary, lacrimal and ethmoid bones (orbital rim and medial wall) –sphenoid and palatine bones 26

27 The Nasal Complex Bones of the nasal cavities and paranasal sinuses Figure 7–14 27

28 The Nasal Complex: Sinuses Sinuses: –air filled chambers inside flat bones –Function: 1.Reduce weight of bone 2.House mucus membranes that moisten and clean incoming air -Found in: -Sphenoid, ethmoid, frontal, palatine, and maxillary bones 28

29 The differences between the skulls of infants, children, and adults. 29

30 Skull Development Intramembranous ossification from many centers of ossification During development: –brain grows more rapidly than cranial bones Growing skull bones are held together by bands of fibrous CT to provide flexibility –Expansion of brain, compression for birth Large intersections of CT between the bones = fontalels (“soft spots”) –Persist until age 5 Around age 5: –Brain stops growing in size, solid sutures form between cranial bones 30

31 The Infant Skull Fusion is not complete at birth: –2 frontal bones –4 occipital bones –several sphenoid and temporal elements Fontanels –Are areas of fibrous connective tissue (soft spots) –Cover unfused sutures in the infant skull –Allow the skull to flex during birth 31

32 The 4 Fontanels Anterior fontanel: –frontal, sagittal, and coronal sutures Occipital fontanel: –lambdoid and sagittal sutures Sphenoidal fontanels: –squamous and coronal sutures Mastoid fontanel: –squamous and lambdoid sutures 32

33 Infant Skull 33

34 Skull Development Abnormalities 1.Craniostenosis: -Premature closure of frontanels, -Without surgery, the brain is crushed 2.Microcephaly: - Brain fails to enlarge - Cranium remains small 34

35 Craniostenosis Microcephaly 35

36 In which bone is the foramen magnum located? A.sphenoid B.occipital bone C.ethmoid D.parietal bone 36

37 Tomás suffers a blow to the skull that fractures the right superior lateral surface of his cranium. Which bone is fractured? A.frontal bone B.right temporal bone C.right parietal bone D.ethmoid 37

38 Which bone contains the depression called the sella turcica? What is located in this depression? A.sphenoid bone; pituitary gland B.ethmoid; olfactory epithelium C.temporal bone; inner ear D.lacrimal bone; tear apparatus 38

39 The vertebral regions, the curvatures of the vertebral column, and their functions. 39

40 The Vertebral Column: 26 Bones The spine or vertebral column: –protects the spinal cord –supports the head and body 7 cervical vertebrae (C 1 -C 7 ) 12 Thoracic vertebrae (T 1 -T 12 ) 5 Lumbar vertebrae (L 1 -L 5 ) 1 Sacrum (5 fused) 1 Coccyx (3-5 fused) 40

41 Regions and Curves of the Vertebral Column 26 bones: –24 vertebrae, the sacrum, and coccyx Vertebral column is not straight –4 curves bring the weight of the body in line with the central axis Figure 7–16 41

42 The Vertebrae Figure 7–20a 42

43 Comparing Vertebrae 43

44 Characteristics of the Sacrum and Coccyx The sacrum: –is curved, more in males than in females –protects reproductive, urinary, and digestive organs The coccyx: –attaches ligaments and a constricting muscle of the anus 44

45 4 Curvatures of the Vertebral Column 1.Cervical curve 2.Thoracic curve 3.Lumbar curve 4.Sacral curve 45

46 Primary Curves Thoracic and sacral curves: –are called primary curves (present during fetal development) –or accommodation curves (accommodate internal organs) 46

47 Secondary Curves Lumbar and cervical curves: –are called secondary curves (appear after birth in first year of life) –or compensation curves (shift body weight for upright posture) –Necessary for bipedalism –Cervical: holds head up –Lumbar: standing 47

48 Abnormalities in Curvature 1.Kyphosis: - exaggerated thoracic curvature 2.Lordosis: - exaggerated lumber curvature 3.Scoliosis: - abnormal lateral curvature 48

49 Construction of Column Vertebral body: stacking –transfers weight along the spine Intervertebral disc: –Spacing between bodies (not C1 and C2) –Annulus Fibrosus: Outside Fibrocartilage –Nucleus pulposus: Inside Gel (cushion) Absorbs Shock –Loss of water from discs = shrinking height 49

50 Construction of Column Elastic ligaments: –link bodies for alignment Intervertebral foramen: –holes formed by spacing from discs, allow spinal nerves to exit column Vertebral arch: –Bone attached to vertebral body, with body it forms vertebral foramen Vertebral Foramen: –Hole for spinal cord Vertebral Canal: –Bony canal for spinal cord –Formed by stacking of vertebral foramen 50

51 Structure of a Vertebra Figure 7–17a,b 51

52 The Vertebral Canal Figure 7–17d,e 52

53 Spina bifida Vertebral arch fails to develop correctly at 3 weeks (fetus) and the spinal cord is unprotected or even exposed 4/1000 births show some degree –Due to lack of folic acid 53

54 Why does the vertebral column of an adult have fewer vertebrae than that of a newborn? A.Vertebrae are absorbed as adult stature is reached. B.Newborns require more support in the cervical region. C.The sacrum and coccyx fuse post- puberty. D.Vertebrae are formed that later become ribs. 54

55 What is the importance of the secondary curves of the spine? A.balances weight of head B.balances weight on lower limbs C.allows walking D.provides greater flexibility 55

56 When you run your finger along a person’s spine, what part of the vertebrae are you feeling just beneath the skin? A.superior articular processes B.pedicles C.transverse processes D.spinous processes 56

57 Joe suffered a hairline fracture at the base of the dens. Which bone is fractured, and where is it located? A.second cervical vertebra; posterior neck B.first cervical vertebra; posterior neck C.occipital bone; posterior base of skull D.sacrum; posterior pelvis 57

58 Examining a human vertebra, you notice that, in addition to the large foramen for the spinal cord, two smaller foramina are on either side of the bone in the region of the transverse processes. From which region of the vertebral column is this vertebra? A.thoracic B.lumbar C.sacral D.cervical 58

59 Why are the bodies of the lumbar vertebrae so large? A.They develop first and therefore have longer to grow. B.To provide more flexibility. C.To distribute weight over a larger area. D.To provide greater protection to the lumbar spinal nerves. 59

60 The significance of articulations between ribs, thoracic vertebrae, and sternum. 60

61 The Thoracic Cage The skeleton of the chest: –supports the thoracic cavity Consists of: –24 Ribs –1 sternum (breastbone) 61

62 The Sternum The sternum: –a flat bone –in the midline of the thoracic wall 62

63 The Rib Cage Formed of ribs and sternum Figure 7–22a 63

64 Articulations of Ribs and Vertebrae Figure 7–22b 64

65 Functions of the Thoracic Cage Protects organs of the thoracic cavity: –heart, lungs, and thymus Attaches muscles: –for respiration –of the vertebral column –of the pectoral girdle –of the upper limbs 65

66 The Ribs Figure 7–23 66

67 Functions of Ribs Ribs: –are flexible –are mobile –can absorb shock Rib movements (breathing): –affect width and depth of thoracic cage –changing its volume 67

68 Ribs Ribs (costae): –are 12 pairs of long, curved, flat bones –extending from the thoracic vertebrae Ribs are divided into 3 types: 1. 7 pairs of true ribs: Separate cartilage to attach to sternum 2. 3 pairs of false ribs: Common shared cartilage to attach to sternum 3. 2 pairs of floating ribs: - no cartilage, no attachment to sternum 68

69 KEY CONCEPT The axial skeleton: –protects the brain, spinal cord, and visceral organs of the chest Vertebrae: –conduct body weight to the lower limbs Lower vertebrae are larger and stronger: –because they bear more weight 69

70 How could you distinguish between true ribs and false ribs? A.True ribs attach directly to the sternum by their own costal cartilage. B.True ribs are entirely bony. C.False ribs are not part of the thoracic cage. D.True ribs are attached only to the sternum. 70

71 Improper administration of cardiopulmonary resuscitation (CPR) can result in a fracture of which bone(s)? A.cervical vertebra and ribs B.thoracic vertebra and ribs C.sternum and thoracic vertebra D.sternum and ribs 71

72 What are the main differences between vertebrosternal and vertebrochondral ribs? A.Vertebrosternal ribs attach to the sternum. B.Vertebrochondral ribs attach to costal cartilage. C.Vertebrosternal ribs increase in curvature and length from D.All of the above are true. 72


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