The Skeletal System

1. The Skeletal System

2. Function of Bones • Support – form the framework that supports the body and cradles soft organs • Protection – provide a protective case for the brain, spinal cord, and vital organs • Movement – provide levers for muscles • Mineral storage – reservoir for minerals, especially calcium and phosphorus • Blood cell formation – hematopoiesis occurs within the marrow cavities of bones

3. Bone Markings • Bulges, depressions, and holes that serve as: • Sites of attachment for muscles, ligaments, and tendons • Joint surfaces • Conduits for blood vessels and nerves

4. Bone Markings: Projections – Sites of Muscle and Ligament Attachment • Tuberosity – rounded projection • Crest – narrow, prominent ridge of bone • Trochanter – large, blunt, irregular surface • Line – narrow ridge of bone

5. Bone Markings: Projections – Sites of Muscle and Ligament Attachment • Tubercle – small rounded projection • Epicondyle – raised area above a condyle • Spine – sharp, slender projection • Process – any bony prominence

6. Bone Markings: Projections – Projections That Help to Form Joints • Head – bony expansion carried on a narrow neck • Facet – smooth, nearly flat articular surface • Condyle – rounded articular projection • Ramus – armlike bar of bone

7. Bone Markings: Depressions and Openings • Meatus – canal-like passageway • Sinus – cavity within a bone • Fossa – shallow, basinlike depression • Groove – furrow • Fissure – narrow, slitlike opening • Foramen – round or oval opening through a bone

8. The Skeletal and Muscular Systems Video

9. There are 206 bones in the human body

11. A. The axial skeleton includes the skull and the vertebral column.

12. Frontal View of the Skull

13. The Skull • The skull, the body’s most complex bony structure, is formed by the cranium and facial bones • Cranium – protects the brain and is the site of attachment for head and neck muscles • Facial bones • Supply the framework of the face, the sense organs, and the teeth • Provide openings for the passage of air and food • Anchor the facial muscles of expression

14. Eight cranial bones – two parietal, two temporal, frontal, occipital, sphenoid, and ethmoid Cranial bones are thin and remarkably strong for their weight Anatomy of the Cranium

15. Skull: Posterior View

16. Parietal Bones and Major Associated SuturesForm most of the superior and lateral aspects of the skull

18. Superior View of the Skull

19. Posterior View of the Skull

20. Lateral View of the Skull

22. 1.Parietal Bone 2. Coronal Suture 3. Frontal Bone 4. Nasal Bone 5.Vomer 6. Lacrimal Bone 7. Orbital Part of Ethmoid 8. Zygomatic Bone 9. Maxilla 10. Body of Mandible 11. Ramus of Mandible 12.Coronoid Process 13.Mandibular Condyle 14.Mental Foramen 15.Styloid Process 16. External Acoustic Meatus 17. Mastoid Process 18. Zygomatic Process 19.Temporal Bone 20. Greater Wing of Sphenoid 21.Inferior Temporal Line 22. Superior Temporal Line 23.Squamosal Suture 24.Lambdoidal Suture 25.Occipital Bone

23. Bones of the Skull

24. Inferior of the Cranial Vault

25. The bone at the top is the Frontal Bone. The tongue shaped bone below the Frontal Bone is the Ethmoid Bone. Below that is the Sphenoid Bone. To the left and the right in below the Sphenoid Bone are the Left and Right Temporal Bones. In the Occiput at the bottom of the picture you will notice a large opening, called the Foramen Magnum, through which the spinal cord passes.  (Photo by Paula Kliewer Photography)

26. Inferior View of the Skull

29. 1.Anterior Palatine Foramen 2. Palatine Process of Maxilla 3. Palatine 4. Greater Palatine Foramen 5.Lesser Palatine Foramen 6. Pterygoid Processes of Sphenoid 7.Zygomatic Process 8. Squamous Part of Temporal Bone 9. Mandibular Fossa 10. Styloid Process 11.Stylomastoid Foramen 12. Mastoid Process 13.Mastoid Foramen 14. Superior Nuchal Line 15. External Occipital Protruberance 16.Median Nuchal Line 17. Inferior Nuchal Line1 8.Foramen Magnum 19. Condyloid Canal 20.Occipital Condyle 21.Hypoglossal Canal 22.Jugular Foramen 23.Carotid Canal 24.Foramen Spinosum 25.Foramen Ovale 26.Foramen Lacerum 27.Vomer 28.Transverse Palatine Suture 29.Median Palatine Suture

30. Hyoid •  1. Greater horns •  2.Lesser horns •  3.  Body

31. Temporal Bones

32. Sphenoid Bone

33. Ethmoid Bone

34. Wormian Bones • Tiny irregularly shaped bones that appear within sutures

35. Mandible and Its Markings

36. Maxillary Bone

37. Orbits

38. Nasal Cavity

39. Nasal Cavity

40. Paranasal Sinuses

41. Vertebral Column

42. Formed from 26 irregular bones (vertebrae) connected in such a way that a flexible curved structure results Cervical vertebrae – 7 bones of the neck Thoracic vertebrae – 12 bones of the torso Lumbar vertebrae – 5 bones of the lower back Sacrum – bone inferior to the lumbar vertebrae that articulates with the hip bones Vertebral Column

43. Vertebral Column: Curvatures • Posteriorly concave curvatures – cervical and lumbar • Posteriorly convex curvatures – thoracic and sacral • Abnormal spine curvatures include scoliosis (abnormal lateral curve), kyphosis (hunchback), and lordosis (swayback)

44. Anterior and posterior longitudinal ligaments – continuous bands down the front and back of the spine from the neck to the sacrum Short ligaments connect adjoining vertebrae together Vertebral Column: Ligaments

45. Cushionlike pad composed of two parts Nucleus pulposus – inner gelatinous nucleus that gives the disc its elasticity and compressibility Annulus fibrosus – surrounds the nucleus pulposus with a collar composed of collagen and fibrocartilage Vertebral Column: Intervertebral Discs

46. General Structure of Vertebrae • Body or centrum – disc-shaped, weight-bearing region • Vertebral arch – composed of pedicles and laminae that, along with the centrum, enclose the vertebral foramen • Vertebral foramina – make up the vertebral canal through which the spinal cord passes

47. Spinous processes project posteriorly, and transverse processes project laterally Superior and inferior articular processes – protrude superiorly and inferiorly from the pedicle-lamina junctions Intervertebral foramina – lateral openings formed from notched areas on the superior and inferior borders of adjacent pedicles General Structure of Vertebrae

48. Seven vertebrae (C1-C7) are the smallest, lightest vertebrae C3-C7 are distinguished with an oval body, short spinous processes, and large, triangular vertebral foramina Each transverse process contains a transverse foramen Cervical Vertebrae

49. The atlas 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 Cervical Vertebrae: The Atlas (C1)

50. The axis has a body, spine, and vertebral arches as do other cervical vertebrae 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 Cervical Vertebrae: The Axis (C2)