SKELETAL SYSTEM PRESENTATION.pptx by Daniel Kaiwe

Well prepared by goodness liphale from Kamuzu university of health sciences (KUHeS)

1. Human Anatomy and Physiology SKELETAL SYSTEM Course lecturer : GOODNESS LIPHALE [email protected]

2. THE SKELETAL SYSTEM THE SKELETON The flexible , bony framework found in all vertebrate. Parts of the skeletal system include : Bones (skeleton) Joints Cartilages Ligaments

3. Functions of the Skeletal System 1. Movement : Muscles provide the force, while bones serve as the levers. Skeletal system provides points of attachment for muscles. Together , bones and muscles produce movement of the body in its environment. 2 . Support: The backbone is the main support center for the upper body. It holds your head up Muscle attached to bones!!

4. Functions of the Skeletal System 3 . Protection: The bones of your skull protect your brain. Your ribs protect your lungs and heart from injury. 4. Makes Blood: Red, white blood cells and platelets in a process called hemopoiesis are formed by tissue called Bone marrow , which is in the center of the bone.

5. Functions of the Skeletal System 5 . Storage and Mineral homeostasis Bone tissue stores calcium and phosphorus. When needed, endocrine glands secrete hormones, which act on bone to either release calcium and phosphorus into the blood or store excess minerals in the bone extracellular matrix. Bones store minerals , such as calcium and phosphorus, for use by the body

6. 6. Triglyceride storage Yellow bone marrow within bone is composed mostly of adipose cells, which store triglycerides (fats). In a newborn, all bone marrow is red, but it eventually changes into yellow marrow with increasing age.

7. OTHER FUNCTIONS INCLUDE: 7. SOUND PRODUCTION 8. MANTAINING BODY SHAPE

8. F our types of bones, based on shape: 1. Long bones They are longer, wide and have knobby ends where the articulations form. Their slightly curved structure gives them strength. Long bones include those of the arms, legs, fingers, and toes. 2. Short bones A re equal in length and width, making them nearly cube-shaped. Examples include most bones of the ankles and the wrists . 3. Flat bones A re thin and provide both protection and surfaces for muscle attachments. The bones of the skull, sternum, and ribs are all flat bones. 4. Irregular bones H ave complex shapes, such as those of the face and vertebral column.

9. Classification of Bones on the Basis of Shape Figure 5.1

10. Classification of Bones 1. Long bones Have a shaft with heads at both ends Contain mostly compact bone Examples: Femur, humerus , metacarpals

11. Classification of Bones 2 . Flat bones Thin & often curved Thin layers of compact bone around a layer of spongy bone Examples: Skull, ribs, sternum

12. Classification of Bones 3 . Short bones Generally cube-shape Contain mostly spongy bone Examples: Carpals, tarsals

13. 4.Long bone Gross Anatomy of a Long Bone Diaphysis Shaft Composed of compact bone Figure 5.2a

14. Classification of Bones 4. Irregular bones Odd shapes Do not fit into other categories Example: Vertebrae and pelvis

15. Gross Anatomy of a Long Bone Epiphysis Ends of the bone Composed mostly of spongy bone Covered by articular cartilage Articulates with another bone at a joint Figure 5.2a

16. Structures of a Long Bone Periosteum Outside covering of the diaphysis – isolates bone from surrounding tissues Fibrous connective tissue membrane – provides passage for blood vessels & nerves Figure 5.2c

17. Structures of a Long Bone Articular cartilage Covers the external surface of the epiphyses Hyaline cartilage Decreases friction at joint surfaces

18. Structures of a Long Bone Sharpey’s fibers - Secure periosteum to underlying bone

19. Bone Structure Typical Four Layers: Periosteum: Covers Bones Compact Bone : Lies beneath the periosteum Spongy Bone : Lies beneath the compact bone Bone Marrow : Fills the gaps between the spongy bone BONE TYPES 1. Compact bone 2.Spongy bone

20. Structures of a Long Bone Medullary cavity Cavity of the shaft – lined by the endosteum Contains yellow marrow (mostly fat) in adults Contains red marrow (for blood cell formation) in infants Figure 5.2a

21. Bone Markings Surface features of bones Sites of attachments for muscles, tendons, and ligaments Passages for nerves and blood vessels ***You are responsible for the bone markings on your notes page*** What they are and their function?

22. Bone Formation Ossification Process of replacing other tissues with bone Bone is composed chiefly of osseous tissue It is a specialized connective tissue composed of intercellular material , 1. calcified material, 2. bone matrix 3. three types of cells namely ; Osteoblasts Osteoclasts Osteocytes .

23. Types of Bone Cells Osteoblasts : Responsible for osteogenesis (bone formation) Produce new bone matrix Promote the deposition of calcium salts in the bone matrix With the aid of enzymes, calcium compounds are deposited within the bone matrix forming hardened bone.

24. Types of Bone Cells Osteocytes Once the matrix has hardened around them, osteoblasts are referred to as Osteocytes - Mature bone cells Maintain normal bone structure Recycle calcium salts Assist in bone repair

25. Types of Bone Cells Osteoclasts Involved in the resorption and remodeling of bone tissue - Bone-destroying cells Produce large amounts of acids and enzymes Osteolysis – as bony matrix dissolves, stored minerals are released INTO BLOOD Helps regulate BLOOD calcium and phosphate levels

26. Bone remodeling Normal process of protein and mineral composition being removed and replaced in a bone matrix . Throughout life, bone is constantly made and destroyed Osteoblasts and osteoclasts regulate bone formation and bone destruction. During some stages, e.g childhood , formation exceeds destruction , allowing for growth of the skeleton. For a short period of time after ossification processes cease, formation and destruction are fairly equivalent. As a person ages, destruction often exceeds formation , leading to bone loss.

27. The remodeling process allows for mineral homeostasis, as well as repair of damaged bone tissue. Remodeling is affected by many factors: Hormones : Parathyroid hormone (PTH)—Stimulates osteoclasts Calcitonin—Stimulates osteoblasts Human growth hormone ( hGH )—Stimulates cartilage and bone growth Insulin-like growth factor (IGF)—Stimulates cartilage and bone growth Sex hormones—Sex-related differences in skeletal growth

28. Minerals Availability of calcium, magnesium, and phosphorus Vitamins A, C, and D Activity level —Active versus sedentary lifestyle Die

29. Conti…….. The external and internal surfaces of bones are covered by layers of bone-forming cells and connective tissue. The outer layer, periosteum, consists of collagen fibers and fibroblast . The endosteum lines all internal surfaces of cavities within the bone and Contain osteoblasts for bone formation.

30. Functions of the endosteum and the periosteum Nutrition of osseous tissue Provision of continuous supply of new osteoblasts for repair and growth of bone. The blood and nerve supply of bone is also carried within the layers of the endosteum and periosteum. Hence precaution are taken during surgery to preserve the endosteum and the periosteum . Note

31. BONE FRACTURES

32. Bone Fractures A break in a bone A fracture in which the bone breaks cleanly but does not penetrate the skin is a closed (or simple ) fracture . When the broken bone ends penetrate through the skin, the fracture is open (or compound ). Some of the many common types of fractures are illustrated and described in the table below

33. Common Types of Fractures Table 5.2

34. Types of Bone Fractures Comminuted - bone fragments into many pieces Compression - bone is crushed ( due to porous bone) Depressed - broken bone is pressed inward (e.g. in skull) Transverse - break occurs across the long axis of a bone

35. Types of Bone Fractures Impacted - broken bone ends are forced into each other Spiral - ragged break as a result of excessive twisting of bone E piphyseal - break occurring along epiphyseal line/plate Greenstick - bone breaks incompletely

36. Treating Bone Fractures

37. Fractures treatment T he broken ends of the bones must be brought together and aligned in a process called reduction . The ends must then be immobilized for healing. Reduction can be accomplished by manipulating the broken ends of the bone without rupturing the skin (closed reduction) or by surgical insertion of screws, pins ,(open reduction).

38. Bones take many months to heal completely because the fracture interferes with the blood supply to the bone , and the bone’s strength comes from its extracellular matrix that has also been disrupted by the fracture

39. THE HEALING PROCESS IN BONE FTRACTURES Usually, after fracture, bones are able to repair themselves . FOUR STAGES MONTHS 1 . Formation of fracture hematoma • Broken blood vessel leaks blood, which clots • Nearby bone cells die • Phagocytes and osteoclasts digest dead cells, debris , and bone tissue in and around hematoma

40. 2 . Fibrocartilaginous callus formation • Fibroblasts from periosteum invade site and produce collagen fibers • Chondroblasts from periosteum produce fibrocartilage • These events produce fibrocartilaginous callus that bridges the broken ends of bone

41. 3 . The bony callus forms. M ore osteoblasts and osteoclasts migrate into the area and multiply. The fibrocartilage callus is gradually replaced by the bony callus made of spongy bone.

42. 4 . Bone remodeling • Osteoclasts resorb dead fragments of original bone • Compact bone replaces spongy bone around the fracture peripher

43. Bone growth and repair of the fracture Bone growth is usually associated with partial resorption of preformed tissue. Simultaneously there is laying down of new bone (which exceeds the rate of bone loss ). This permits the shape of the bone to be maintained as it grows. Cranial bones grow mainly because of the formation of bone tissue by the periosteum between the sutures and on the external bone surface.

44. In long bones the transformation of cartilage into bone begins at the centre of the shaft. The diaphysis increases in length due to osteogenic activity of epiphyseal plates and it increases in width due to formation of bone by the periosteum on the external surface

45. TWO MAJOR SUBDIVISIONS OF THE SKELETAL SYSTEM The 206 bones in the adult human skeleton are divided into two categories. TWO MAJOR PARTS OR REGIONS OF THE SKELETON THE AXIAL THE APPENDICULAR SKELETONS

46. The axial skeleton The axial skeleton forms the longitudinal axis of the body. It can be divided into three parts: The skull The vertebral column The thoracic cage - thorax

47. The skull The skull, consists of 22 bones. It has two groups of bones: Cranial bones - 8 Facial bones - 14 The cranial bones protect the brain and form attachment points for the meninges and the muscles The facial bones house the openings to the airways and the digestive system. Also protect the sensory organs and provide attachments for facial muscles.

48. CRANIAL BONES

49. CRANIAL BONES The frontal: bone forms the forehead, roofs of the eye sockets, and front part of the cranial floor . The parietal bones (2 ): F orm the sides and roof of the cranium The temporal bones (2 ): Form the lower side of the cranium and part of the cranial floor. • They form joints with the jawbone (mandible) called the temporomandibular joints (TMJ )

50. The occipital bone : Forms the back part of the skull and most of the cranial floor . The medulla, spinal cord, and vertebral and spinal arteries all pass through its foramen magnum . The first cervical vertebra attaches to the occipital bone. The sphenoid bone : Is in the middle of the cranial floor and is where all the other cranial bones attach.

51. It contains sphenoidal sinuses, which drain into the nasal cavity. The pituitary gland sits in a depression of the sphenoid bone called the sella turcica .

52. The ethmoid bone : Forms the anterior part of the cranial floor, the medial part of the eye sockets, and superior portions of the nasal cavity. has sinuses that warm and moisten inhaled air and trap foreign particles

53. FACIAL BONES

54. FACIAL BONES Nasal bones (2 ): form the bridge of the nose . Maxillae ( 2 ): Form the upper jawbone and join with all the other facial bones except the mandible (lower jawbone): • Each maxilla has a maxillary sinus that empties into the nasal cavity. • Palatine bones ( 2 ): Form the posterior portion of the hard palate, part of the lower eye sockets, and part of the floor and the sides of the nasal cavity. • The mandible: Is the largest, strongest facial bone and the only one that moves

55. Zygomatic bones (2 ) or cheekbones : Form the cheek The vomer : Joins with the maxillae and the palatine bones to form the floor of the nasal cavity. Look for other remaining facial bones……..

56. The Skull Has Many Unique Features The skull has unique features, such as sutures, sinuses, and fontanels (soft spots at birth and early infancy

57. A suture is a special type of immovable joint that joins most of the skull bones. Example of major sutures in the skull • The coronal suture unites the frontal bone and two parietal bones. • The sagittal suture attaches the two parietal bones

58. Fontanels

59. Fontanels the first “long bones” in the very young fetus are formed of hyaline cartilage, and the earliest “flat bones” of the skull are actually fibrous membranes . As the fetus develops and grows , all of the bone models are converted to bone. At birth, the skull has fibrous regions that have yet to be converted to bone . These fibrous membranes connecting the cranial bones are called fontanels. The rhythm of the baby’s pulse can be felt in these “soft spots ,

60. The fontanels allow the fetal skull to be compressed slightly during birth. In addition , because they are flexible, they allow the infant’s brain to grow during the latter part of pregnancy and early infancy. This would not be possible if the cranial bones were fused by sutures, as in the adult skull. The fontanels usually fully ossify by 2 years of age

61. Vertebral column-spine

62. Vertebral column-spine It serving as the axial support of the body . It extends from the skull, which it supports, to the pelvis, where it transmits the weight of the body to the lower limbs The common features of vertebrae • Body, or centrum : disclike , weight-bearing part of the vertebra • Vertebral arch : arch formed from the joining of all posterior extensions, • Vertebral foramen: canal through which the spinal cord passes . • Transverse processes: two lateral projections from the vertebral arch.

63. 1. Cervical vertebrae (7 ): Are in the neck region . Each cervical vertebra has three openings (foramina): A larger, central opening (vertebral foramen) for the spinal cord, and two transverse foramina, passages for blood vessels and nerves. 2. Thoracic vertebrae (12 ): Are posterior to the chest cavity and serve as attachments for the ribs. 3. Lumbar vertebrae (5 ): form the lower back.

64. 4. The sacrum : Consists of 5 fused vertebrae and forms the posterior wall of the pelvis. Blood vessels and nerves pass through the openings. The coccyx : Sometimes referred to as the tailbone, consists of 4 fused vertebrae.

65. Before birth, the spine consists of 33 separate bones called vertebrae. 9 of these eventually fuse to form the two composite bones, the sacrum and the coccyx, These two construct the inferior portion of the vertebral column . Of the 24 single bones: The 7 vertebrae of the neck are cervical vertebrae, The next 12 are the thoracic vertebrae , The 5 supporting the lower back are lumbar vertebrae

66. The individual vertebrae are separated by pads of flexible fibrocartilage—intervertebral discs They cushion the vertebrae and absorb shock while allowing the spine flexibility. In a young person, the discs have a high water content (about 90 percent) and are spongy and compressible. ASSIGNMENT

67. Joints Articulations of bones – exist wherever two bones meet Functions of joints : S trength & mobility

68. Structural Classification of Joints Fibrous joints - Generally immovable Cartilaginous joints - Immovable or slightly moveable Synovial joints - Freely moveable

69. Functional Classification of Joints Synarthroses – immovable joints Amphiarthroses – slightly moveable joints Diarthroses – freely moveable joints

70. Synarthroses Bony edges are close together and may interlock Suture – bones interlocked and bound together with dense connective tissue (skull)

71. Amphiarthroses Symphysis (cartilaginous): Bones connected by cartilage Examples Pubic symphysis Intervertebral joints Figure 5.27d–e

72. Diarthroses (Synovial Joints) Articulating bones are separated by a joint cavity Typically found at the ends of long bones Synovial fluid is found in the joint cavity Figure 5.24f–h

73. Features of Synovial Joints Joint surfaces are enclosed by a fibrous articular capsule Ligaments reinforce the joint

74. Features of Synovial Joints Bursae – Small packets of connective tissue filled with synovial fluid Shock absorber/ friction reducer Found where tendons or ligaments rub against other tissues

75. Features of Complex Synovial Joints Meniscus - shock absorbing fibrocartilage pad Fat pads – protect the articular cartilages & act as “filler”

76. Types of Synovial Joints Based on Shape Figure 5.29a–c

77. Plane/Gliding Joint Articular surfaces are flat Short slipping or gliding movements Nonaxial - no rotation Carpal and tarsal joints

78. Hinge Joint Cylindrical end of one bone fits into a trough-shaped surface on the other Uniaxial – movement around one axis Elbow & joints of the phalanges

79. Pivot Joint Uniaxial joints – rounded end of one bone fits into a sleeve or ring of bone The atlas and dens of the axis

80. Saddle Joints Biaxial Joint – articulated surfaces have convex and concave surfaces Joint of the thumb

81. Ball-and-Socket Joint Only multiaxial joints – spherical head of one bone fits into the round socket of another Provide greatest variation in motion

82. Inflammatory Conditions Associated with Joints Bursitis – inflammation of a bursa usually caused by a blow or friction Tendonitis – inflammation of tendon sheaths

83. Rheumatism General term describing pain or stiffness arising in the muscular or skeletal system Several major forms of rheumatism: Arthritis – inflammatory or degenerative diseases of joints Also known as degenerative joint disease (DJD) 25% of women and 15 % of men over age 60 show signs of this disorder

84. Clinical Forms of Arthritis Osteoarthritis : Most common chronic arthritis Probably related to normal aging processes – softening, fraying and breakdown of the articular cartilage Exposed bone thickens into spurs – limits movement

85. Clinical Forms of Arthritis Rheumatoid arthritis An autoimmune disease – the immune system attacks the joints Often leads to deformities in hands and feet

86. Clinical Forms of Arthritis Gouty Arthritis : Inflammation of joints is caused by a deposition of urate crystals from the blood Needle like crystals usually accumulate in one joint – typically the big toe Can usually be controlled with diet

87. Skeletal Disorders Heterotopic Bones : A bnormal development of osteoblasts in normal connective tissues Fibrodysplasia Ossificans Progressiva : rare genetic heterotopic disorder Muscles of the back, neck & upper limbs gradually replaced by bone

88. Rickets Softening and bending of the bones due to Vitamin D 3 deficiency Children get bowed legs as they bend under the weight of the body No longer common IN rich countries due to dietary supplements

89. Scurvy Vitamin C deficiency causes reduction in osteoblast activity Weak and brittle bones Common on ships

90. Osteopenia Bones become thinner and weaker with age Reduction in bone mass begins between ages 30 – 40 Important to build strong bones as a child/ young adult

91. Osteopenia Osteoblast activity declines Osteoclast activity remains normal Women lose about 8% and men about 3% of their bone mass every decade Epiphyses, vertebrae & jaws affected the most Fragile joints/limbs, height reduction and tooth loss

92. Osteoporosis Bone-thinning disease that afflicts half of women over 65 and 20% of men over 70 Bones are brittle and fracture easily Often causes kyphosis due to vertebral collapse Caused partially by estrogen deficiency after menopause Other factors include lack of calcium, protein and vitamin D in the diet, smoking and insufficient weight-bearing exercise

93. Osteoporosis

94. Osteomyelitis I s inflammation of the bone that is usually due to infection. S oft tissue swelling, thickened synovial covering the posterior aspect affecting the articular joint space and bursae .

95. Osteomalacia Refers to a marked softening of your bones, most often caused by severe vitamin D deficiency. The softened bones of children and young adults with osteomalacia can lead to bowing during growth, especially in weight-bearing bones of the legs. Osteomalacia in older adults can lead to fractures

96. END For I know the plans I have for you, declares the LORD, plans to prosper you and not to harm you, to give you a future and a hope