Ch07 08


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Ch07 08

  1. 1. Chapters 7 & 8
  2. 2. Table 7.1 – Bones of the adult skeleton <ul><li>206 named bones make up the adult skeleton </li></ul><ul><li>These bones are divided between 2 divisions: </li></ul><ul><ul><li>Axial skeleton (80 bones) </li></ul></ul><ul><ul><ul><li>Includes bones found along the body’s long axis </li></ul></ul></ul><ul><ul><li>Appendicular skeleton (126 bones) </li></ul></ul><ul><ul><ul><li>Includes bones of the upper and lower limbs. </li></ul></ul></ul>
  3. 3. Table 7.2 – Bones of the adult skull
  4. 4. General features of the skull <ul><li>Bones of the skull form, or have contained within individual bones, a number of spaces including the cranial cavity, bony labyrinth, and paranasal sinuses. </li></ul><ul><li>Bones of the skull have numerous surface markings which aid in their identification, including holes through the bone (foramina), and bony projections (e.g., a spine). </li></ul>
  5. 5. Facial bones – maxillae <ul><li>The paired maxillary bones fuse at the midline to form the upper jaw. </li></ul><ul><li>Internally, the maxillae contribute to the inferior wall of the orbit, the walls and floor of the nasal cavity, and most of the hard palate. </li></ul><ul><li>The body of the maxillae are hollowed out internally to form a pair of large sinuses. </li></ul>
  6. 6. Cleft Palate/Lip <ul><li>Cleft palate: failure of the palatine processes of the maxillary bones to unite during weeks 10 to 12 of development </li></ul><ul><li>Cleft lip: split in the upper lip due to failure of fusion of the maxillary and medial nasal processes </li></ul><ul><li>Associated with congenital anomalies/diseases </li></ul><ul><li>Treatment: surgical repair </li></ul>
  7. 9. Orbits <ul><li>Three cranial bones, and four facial bones, form each orbit. </li></ul><ul><li>Associated with each orbit are five openings: </li></ul><ul><ul><li>optic foramen (canal) </li></ul></ul><ul><ul><li>superior orbital fissure </li></ul></ul><ul><ul><li>inferior orbital fissure </li></ul></ul><ul><ul><li>supraorbital foramen </li></ul></ul><ul><ul><li>lacrimal fossa </li></ul></ul>
  8. 10. Figure 7.10 – Orbit of the eye
  9. 11. Black Eye <ul><li>Bruising around the eye due to facial injury (ecchymosis) </li></ul><ul><li>Trauma causing swelling and dark discoloration </li></ul><ul><li>Frontal bone fracture, nasal fracture, facelift/jaw surgery </li></ul><ul><li>As it heals, swelling and bruise generally fades away </li></ul><ul><li>Ice helps to decrease swelling by constricting blood vessels, by decreasing fluid accumulation, and by cooling and numbing the area. </li></ul>
  10. 13. Paranasal sinuses <ul><li>These are cavities within frontal, sphenoid, ethmoid, and maxillary bones. </li></ul><ul><li>They are lined with the same mucous membranes that line the nasal cavity. </li></ul><ul><li>The sinuses lighten the skull’s mass and increase the surface area of the nasal mucosa, thereby helping to moisten and cleanse inhaled air. </li></ul><ul><li>In addition, the paranasal sinuses serve as (echo) resonating chambers that intensify and prolong sounds, thereby enhancing the quality of a person’s voice. </li></ul>
  11. 14. Figure 7.11 – Paranasal sinuses
  12. 15. Fontanels <ul><li>Fontanels are areas of unossified mesenchyme (soft spots) that will be replaced with bone by intramembranous ossification. </li></ul><ul><li>Functionally, the fontanels provide flexibility to the fetal skull, allowing the skull to change shape as it passes through the birth canal, and they permit rapid growth of the brain. </li></ul><ul><li>Posterior fontanel closes first several months, while the larger anterior fontanel close at two years. </li></ul><ul><li>Clinical: palpation of anterior fontanel </li></ul><ul><li>-sunken: dehydration </li></ul><ul><li>-bulging: increased intracranial pressure </li></ul>
  13. 16. Figure 7.12 – Fontanels at birth
  14. 17. Cranial fossae <ul><li>The cranium has three distinct regions called cranial fossae that correspond to the major contours of the inferior surface of the brain. </li></ul><ul><li>From anterior to posterior, they are the </li></ul><ul><ul><li>anterior cranial fossa, </li></ul></ul><ul><ul><li>middle cranial fossa, and </li></ul></ul><ul><ul><li>posterior cranial fossa. </li></ul></ul>
  15. 18. Anterior cranial fossa <ul><li>Formed by the portions of the frontal bone that constitutes the roof of the orbits and nasal cavity, the crista galli and cribriform plate of the ethmoid bone, and the lesser wings and part of the body of the sphenoid bone. </li></ul><ul><li>This fossa surrounds the frontal lobes of the cerebral hemispheres of the brain. </li></ul>
  16. 19. Middle cranial fossa <ul><li>Located inferior and posterior to the anterior cranial fossa, the middle cranial fossa is shaped like a butterfly. </li></ul><ul><li>The median portion is formed by part of the body of the sphenoid bone, and the lateral portions are formed by the greater wings of the sphenoid bone, temporal squama, and parietal bone. </li></ul><ul><li>This fossa cradles the temporal lobes of the cerebral hemispheres. </li></ul>
  17. 20. Posterior cranial fossa <ul><li>This is the largest of the fossae. </li></ul><ul><li>It is formed mostly by the occipital bone and the petrous and mastoid portions of the temporal bone. </li></ul><ul><li>This is a very deep fossa that accommodates the cerebellum, pons, and medulla oblongata of the brain. </li></ul>
  18. 21. Figure 7.13 – Cranial fossae
  19. 22. Hyoid bone <ul><li>The unpaired hyoid bone does not articulate with any other bone. </li></ul><ul><li>It is suspended from the styloid processes of the temporal bones by ligaments and muscles, serving as a attachment site for muscles of the tongue, neck and pharynx. </li></ul><ul><li>The hyoid bone consists of a horizontal, rectangular body, and paired projections called the lesser horns and the greater horns. </li></ul>
  20. 23. Figure 7.14 – Hyoid bone
  21. 24. Vertebral column <ul><li>Also known as the spine or backbone , it is composed of a series of bones called vertebrae which surrounds and protects the nervous tissue of the spinal cord. </li></ul><ul><ul><li>The a dult vertebral column typically contains 26 vertebrae: </li></ul></ul><ul><ul><li>7 cervical vertebrae </li></ul></ul><ul><ul><li>12 thoracic vertebrae </li></ul></ul><ul><ul><li>5 lumbar vertebrae </li></ul></ul><ul><ul><li>5 fused sacral vertebrae that form the sacrum </li></ul></ul><ul><ul><li>4 fused coccygeal vertebrae that form the coccyx </li></ul></ul>
  22. 25. Figure 7.15 – Vertebral column
  23. 26. Figure 7.16 – Structures common to most vertebrae
  24. 27. Parts of a typical vertebra <ul><li>Vertebrae typically consist of a body , a vertebral arch , and several processes . </li></ul><ul><ul><li>Body – large and block-like; separated by intervertebral discs; it is a weight-bearing structure. </li></ul></ul><ul><ul><li>Vertebral arch – together with the body, the arch surrounds and protects the spinal cord. Pedicles form the lateral walls, and laminae the posterior walls. </li></ul></ul><ul><ul><li>Processes (7) – A transverse process extends laterally where a lamina and pedicle join. A spinous process projects posteriorly at the junction of the laminae. Paired a rticular processes articulate with an adjacent superior, and an adjacent inferior, vertebrae. </li></ul></ul>
  25. 28. Cervical vertebrae – distinguishing features <ul><li>Only cervical vertebrae a transverse foramen within the transverse process. </li></ul><ul><li>The atlas , or C 1 , is a bony ring with no body. Its articulations with the head permit the movement we associate a head-nod (yes). </li></ul><ul><li>The axis , or C 2 , has a peg-like process that articulates with C 1 permitting the movement we associate with a head-shake (no). </li></ul><ul><li>C 3 – C 7 have the most features in common of the cervical vertebrae. </li></ul>
  26. 29. Figure 7.17 – Cervical vertebrae
  27. 30. Thoracic vertebrae – distinguishing features <ul><li>Thoracic vertebrae are considerably larger and stronger than cervical vertebrae, and are easily identified by their costal facets which articulate with the tubercles of ribs. </li></ul><ul><li>The bodies of thoracic vertebrae articulate with the heads of ribs, except for T 11 and T 12 . </li></ul>
  28. 31. Figure 7.18 – Thoracic vertebrae
  29. 32. Lumbar vertebrae – distinguishing features <ul><li>Lumbar vertebrae are the largest and strongest of the unfused vertebrae in the vertebral column. </li></ul><ul><li>They are readily identified by their large size, and an absence of costal articular facets. </li></ul>
  30. 33. Figure 7.19 – Lumbar vertebrae
  31. 34. Sacrum <ul><li>Fusion of the 5 sacral vertebrae result in the formation of the sacrum , a process that can last from the age of 16 – 30 years; transverse lines mark the sites of fusion. </li></ul>
  32. 35. Coccyx <ul><li>The coccyx is a triangular bone that forms from the fusion of three to five vertebral bones. </li></ul><ul><li>Fusion of coccygeal vertebrae also lasts a number of years, usually from 20 – 30 years of age. </li></ul>
  33. 36. Figure 7.20 – Sacrum and coccyx
  34. 37. Clinical connection – Abnormal curves of the vertebral column <ul><li>Normal curves include the convex cervical & lumbar curves , and the concave thoracic & sacral curves . </li></ul><ul><li>Curves function to </li></ul><ul><ul><li>increase the strength of the column </li></ul></ul><ul><ul><li>maintain balance in the upright position </li></ul></ul><ul><ul><li>absorb shocks during walking </li></ul></ul><ul><ul><li>protect the vertebrae from fracture </li></ul></ul><ul><li>Abnormal curves of the vertebral column include: </li></ul><ul><ul><li>Scoliosis – refers to a lateral bending in the thoracic region </li></ul></ul><ul><ul><li>Kyphosis – describes an increase in the thoracic curve </li></ul></ul><ul><ul><li>Lordosis – describes an increase in the lumbar curve </li></ul></ul>
  35. 41. Pectoral Girdle - Clavicle <ul><li>The clavicle is “S” shaped </li></ul><ul><li>The medial end articulates with the manubrium of the sternum forming the sternoclavicular joint </li></ul><ul><li>The lateral end articulates with the acromion forming the acromioclavicular joint </li></ul>
  36. 42. Pectoral Girdle - Clavicle <ul><li>The clavicle is convex in shape anteriorly near the sternal junction </li></ul><ul><li>The clavicle is concave anteriorly on its lateral edge near the acromion </li></ul>
  37. 43. The Clavicle
  38. 44. Clinical Connection - Fractured Clavicle <ul><li>A fall on an outstretched arm (F.O.O.S.H.) injury can lead to a fractured clavicle </li></ul><ul><li>The clavicle is weakest at the junction of the two curves </li></ul><ul><li>Forces are generated through the upper limb to the trunk during a fall </li></ul><ul><li>Therefore, most breaks occur approximately in the middle of the clavicle </li></ul><ul><li>Median nerve damage from seatbelts via auto accidents, trauma, falls, delivery at birth </li></ul><ul><li>Treat via sling in adult </li></ul>
  39. 45. A Fractured Clavicle - Figure on page 4
  40. 46. Development of the Skeletal System <ul><li>Most skeletal tissue arises from mesenchymal cells </li></ul><ul><li>The skull develops during the fourth week after fertilization </li></ul><ul><li>Fontanels are the spaces between the skull bones during fetal life and infancy </li></ul><ul><li>Upper limb buds form during the fourth week after fertilization followed by the lower limb buds </li></ul><ul><li>During the sixth week, hand plates and foot plates form </li></ul><ul><li>Vertebrae and ribs are formed from sclerotomes of somites </li></ul><ul><li>Failure of proper development of the vertebral arches leads to spina bifida ; decrease with _______ </li></ul>
  41. 47. Development of the skeletal system
  42. 49. Neural tube defects are are one of the more common congenital anomalies to occur. Such defects result from improper embryonic neural tube closure. The most minimal defect is called spina bifida, with failure of the vertebral body to completely form, but the defect is not open. Open neural tube defects with lack of a skin covering, can include a meningocele, in which meninges protrude through the defect. Here is a large meningomyelocele in which the defect is large enough to allow meninges and a portion of spinal cord to protrude through the defect.