1. Essentials of Human Anatomy The Skeletal System 1

2. Bone Bones are organs Bones are composed of all tissue types.
Their primary component is osseous connective tissue.
The matrix is sturdy and rigid due to calcification (also called mineralization).

3. 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
Energy storage (fat in yellow marrow)

4. Support and Protection
Bones provide structural support and serve as a framework for the entire body.
Bones protect many delicate tissues and organs from injury and trauma.

5. Movement Muscles attach to the bones of the skeleton
Contract and pull on bone
Functions as a series of levers.

6. Storage of Mineral and Energy Reserves
More than 90% of the body’s reserves of the minerals calcium and phosphate are stored and released by bone.

7. Hematopoiesis Blood Cell Formation
Blood cell production in red bone marrow
located in some spongy bone.
Red bone marrow contains stem cells
form all of the blood cell types.

8. Changes in the Human Skeleton
In embryos, the skeleton is primarily hyaline cartilage
During development, much of this cartilage is replaced by bone
Cartilage remains in isolated areas
Bridge of the nose
Parts of ribs
Joints

9. Classification of Bones on the Basis of Shape

10. Classification of Bones
Long bones
Generally longer than wide.
Have a shaft with heads at both ends.
Contain mostly compact bone
Examples: Femur, humerus

11. Classification of Bones
Short bones
Generally cube-shape
Contain more spongy bone than compact
Examples: Carpals, tarsals

12. Classification of Bones
Flat bones
Thin and flattened like pancackes.
Usually curved
They have two thin layers of compact bone sandwiching a layer of spongy bone
Examples: Skull, ribs, sternum

13. Classification of Bones
Irregular bones
Do not fit into other bone classification categories
Irregular shape
Example: Vertebrae

14. The Histologic Types: Compact bone ( cortical)
Spongy bone ( cancellous)

15. Compact Bone:
Haversian system, or osteon – the structural unit of compact bone
Lamella – weight-bearing, column-like matrix tubes composed mainly of collagen
Haversian, or central canal – central channel containing blood vessels and nerves
Volkmann’s canals – channels lying at right angles to the central canal, connecting blood and nerve supply of the periosteum to that of the Haversian canal

16. Compact Bone Osteocytes – mature bone cells
Lacunae – small cavities in bone that contain osteocytes
Canaliculi – hairlike canals that connect lacunae to each other and the central canal

17. Compact Bone:

18. Spongy (cancellous) Bone
Does not contain osteons.
trabeculae surrounding red marrow spaces

19. Cell Types of Bone 3 types of cells in bone tissue Osteoblasts:
Form matrix & collagen fibers but can’t divide
Osteocytes:
Mature cells that no longer secrete matrix
Osteoclasts:
Huge cells from fused monocytes (WBC)
Function in bone resorption at surfaces such as endosteum

20. SKLETAL SYSTEM
It is divided into two parts :
Axial
Appendicular

21. Bone Structure - External
Cartilage protection for joints

22. Bone Structure - External
Epiphyses
Expanded ends of long bones
Exterior is compact bone, and the interior is spongy bone
Joint surface is covered with articular (hyaline) cartilage
location of red bone marrow
Epiphyseal line separates the diaphysis from the epiphyses
Epiphyse

23. Bone Structure - External
Diaphysis
Tubular shaft that forms the axis of long bones
Composed of compact bone that surrounds the medullary cavity
Yellow bone marrow (fat) is contained in the medullary cavity
Diaphysis

24. Bone Membranes Periosteum – double-layered protective membrane
Outer fibrous layer
dense regular connective tissue
Inner osteogenic layer
composed of osteoblasts and osteoclasts
Richly supplied with nerve fibers, blood, and lymphatic vessels, which enter the bone via nutrient foramina
Secured to underlying bone by Sharpey’s fibers
Endosteum – delicate membrane covering internal surfaces of bone

25. Blood and Nerve Supply of Bone
Periosteal arteries
Supply periosteum
Nutrient arteries
Enter through nutrient foramen
Supplies compact bone of diaphysis & red marrow
Metaphyseal & epiphyseal aa
Supply red marrow & bone tissue of epiphyses

26. Skeletal system includes
Axial division
Skull and associated bones
Auditory ossicles
Hyoid bones
Vertebral column
Thorax (Thoracic cage )
Ribs sternum
Appendicular division
- Pectoral girdle
- Pelvic girdle

27. The Adult Skull skull is formed of two sets of bones:-
cranium is encloses and protects the fragile brain tissues = 8 bones: frontal, occipital, 2 temporals, 2 parietals, sphenoid and ethmoid
facial bones holed the eyes in an anterior position and allow the facial muscles to show our feelings. = 14 bones: nasals, maxillae, zygomatics, mandible, lacrimals, palatines, inferior nasal conchae, vomer.

28. Bones of the Cranium

29. Frontal View

30. Frontal
Frontal View

31. Parietal
Frontal View

32. Temporal
Frontal View

33. Nasal
Frontal View

34. Vomer
Frontal View

35. Zygoma
Frontal View

36. Maxilla
Frontal View

37. Mandible
Frontal View

38. Frontal View Frontal Parietal Temporal Nasal Vomer Zygoma Maxilla
Mandible
Frontal View

39. Lateral View

40. Frontal
Lateral View

41. Parietal
Lateral View

42. Temporal
Lateral View

43. Nasal
Lateral View

44. Zygoma
Lateral View

45. Maxilla
Lateral View

46. Mandible
Lateral View

47. Sphenoid
Lateral View

48. Occipital
Lateral View

49. Mastoid Process
Lateral View

50. External Auditory Meatus
Lateral View

51. Lateral View Parietal Frontal Sphenoid Nasal Temporal Zygoma Occipital
Maxilla
Mastoid Process
Mandible
External Auditory Meatus
Lateral View

52. Fetal skull The skull of a newborn differs from an adult one:
The infant’s face is very tiny compared to the cranium.
The whole skull is large compared to infant’s body length
The adult skull represents only 1/8th of the total body length, whereas that of new born infant is 1/4th as long as its entire body.
The fetal skull has fibrous cartilage area between the cranial bones.
These membranous area are called fontanels, which allow the fetal skull to be compressed during birth and allow the infant’s brain to be grow.
The fontanels usually closes by age months.

53. Fetal skull

54. Adult Vertebral Column
Formed from 33 bones in the adult
Divided into five major regions
Cervical vertebrae
7 vertebrae of the neck region
Thoracic vertebrae
12 vertebrae of the thoracic region
Lumbar vertebrae
5 vertebrae of the lower back
Sacrum
Inferior to lumbar vertebrae
Articulates with coxal bones
Coccyx
Most inferior region of the vertebral column

56. Intervertebral disks
The single vertebrae are separated by pads of elastic cartilage intervertebral disks
Cushion vertebrae and absorb shocks.
Have a high water content (about 90%) and are compressible.

57. General Structure of Vertebrae

58. Cervical Vertebrae Atlas – 1st; supports head
Axis – 2nd; dens pivots to turn head
transverse foramina
bifid spinous processes
vertebral prominens – useful landmark

59. Thoracic Vertebrae
long spinous processes
Rib facets

60. Lumbar Vertebrae
large bodies
thick, short spinous processes

61. Sacrum five fused vertebrae median sacral crest
posterior sacral foramina
posterior wall of pelvic cavity
sacral promontory

62. Coccyx
Tailbone
Four fused vertebrae

63. Thorax Often called the thoracic cage. Components of the thorax
Sternum– anteriorly
Ribs – laterally
Thoracic vertebrae – posteriorly
Protects thoracic organs (heart, lungs, and major blood vessels).

64. The Thorax

65. Sternum
Breast bone is typical flat bone and the result of fusion of three bones.
Manubrium – superior section
Body – bulk of sternum
Xiphoid process – inferior end of sternum
Attached to the 1st seven pairs of ribs.

66. Ribs The 12 pairs of ribs form the wall of the thoracic cage.
All ribs attach to vertebral column posteriorly
True ribs - superior seven pairs of ribs Attach directly to sternum by costal cartilage
False ribs – inferior five pairs of ribs
Have cartilages attachment to the sternum that are indirect or are not attached at all.
Ribs 11–12 are known as floating ribs

67. The Thoracic cage

68. Ribs

69. Ribs

70. APPENDICULAR SKELETON
It is formed of :
Pectoral girdle
Pelvic girdle
Bones of the upper and lower limbs.

71. PECTORAL GIRDLE It is formed of :
CLAVICLE which holds the arm away from the thorax.
SCAPULA (WING).

72. Clavical

73. Scapula

74. UPPER LIMB ARM :Humerus FORE ARM: Radius & Ulna.
Long bones They are formed of Epiphysis on each end. Diaphysis a tubular shaft. It is covered externally by the periosteum.

75. HAND WRIST : Carpal bones. PALM : Metacarpal bones.
FINGERS : Phalanges.
They are examples of short bones.

76. PELVIC GIRDLE Formed of the two HIP bones.
Each hip bone is formed of three parts :
ILium.
Ischium.
Pubis.
The hip bones and the sacrum form the bony pelvis.

78. LOWER LIMB
THIGH : Femur.
LEG : Tibia & Fibula.
Also Patella bone

79. FOOT
TARSUS : Tarsal bones.
Metatarsals.
Phalanges.