Skeletal System - Chapter 7


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Skeletal System - Chapter 7

  1. 1. The Skeleton Chapter 7
  2. 2. Axial Skeleton <ul><li>Structured from 80 bones </li></ul><ul><li>Divided into 3 major regions </li></ul><ul><ul><li>The skull </li></ul></ul><ul><ul><li>The vertebral column, </li></ul></ul><ul><ul><li>The bony thorax </li></ul></ul><ul><li>It protects the brain, spine, and thorax organs while supporting the head neck and trunk. </li></ul>
  3. 3. The Skull    
  4. 4. Skull <ul><li>Most complex bony structure </li></ul><ul><li>Formed by cranial and facial bones (22 in all) </li></ul><ul><li>All skull bones are united by joints called sutures, which have a saw-tooth or serrated appearance and are named for the bones they connect. </li></ul>
  5. 5. Facial Bones <ul><li>Form the framework of the face </li></ul><ul><li>Contain cavities for sense organs (sight, taste, and smell) </li></ul><ul><li>Provide openings for air passages </li></ul><ul><li>Secure the teeth </li></ul><ul><li>Anchor facial muscles </li></ul>
  6. 6. Parts of the Skull
  7. 7. The Cranium The cranium is made of eight cranial bones. It protects the brain, serving as a “helmet.”
  8. 8. Frontal Bone <ul><li>Anterior portion of the cranium </li></ul><ul><li>Most anterior part is the frontal squama (forehead). </li></ul><ul><li>The forehead ends at the supraorbital margins (thick part under the eyebrows). </li></ul><ul><li>It forms the upper part of the orbits (eye sockets). </li></ul><ul><li>The glabella is the smooth portion between the orbits. </li></ul><ul><li>Frontonasal suture is where the frontal bone meets the nasal bone. </li></ul>
  9. 9. Parietal Bones and Major Sutures <ul><li>2 curved, rectangular bones that form the superior and lateral aspects of the skull. </li></ul><ul><li>They are the bulk of the cranium. </li></ul><ul><li>4 of the largest sutures occur at parietal joints: </li></ul><ul><ul><li>Coronal suture – parietal meets frontal </li></ul></ul><ul><ul><li>Sagittal suture – right and left parietals meet at midline </li></ul></ul><ul><ul><li>Lambdoidal suture – parietal meets occipital </li></ul></ul><ul><ul><li>Squamous suture – parietal meets temporal </li></ul></ul>
  10. 10. Occipital Bone <ul><li>Forms most of the skull’s posterior wall and base </li></ul><ul><li>Internally, it forms the walls of the posterior cranial fossa, which supports the cerebellum. </li></ul><ul><li>At the bottom is the foramen magnum (“big hole”) where the brain connects with the spinal cord. </li></ul>
  11. 11. Occipital (con’t) <ul><li>Occipital condyles allow the head to nod. </li></ul><ul><li>The external occipital protuberance is the knob-like projection on the posterior of the skull. </li></ul>
  12. 12. Temporal Bones <ul><li>Temporal bones (2) lie inferior to the parietal bones. </li></ul><ul><li>They are called the temples (Latin: temporous = time) because of gray hair forming signified time passing. </li></ul><ul><li>They have a complicated shape and are described in terms of regions. </li></ul>
  13. 13. Temporal Regions <ul><li>Squamous region: cheekbone and condyle (“ball”) of the lower jawbone </li></ul><ul><li>Tympanic region: external ear canal and styloid process; serves as an attachment point for several muscles of the tongue and neck. </li></ul><ul><li>Mastoid region: facial nerves, neck muscles, and mastoid sinuses </li></ul><ul><li>Petrous region: middle and inner ear cavities, jugular vein, carotid arteries (supply 80% of the blood to the brain) </li></ul>
  14. 14. Sphenoid Bone <ul><li>Butterfly-shaped </li></ul><ul><li>Wedged in the other cranial bones </li></ul><ul><li>Consists of a central body and 3 processes. </li></ul>
  15. 15. Ethmoid Bone <ul><li>Between the sphenoid and nasal bones </li></ul><ul><li>Forms the roof of the nasal cavities </li></ul><ul><li>Punctured by olfactory foramina (holes), which allow nerves to pass through that aid in smelling. </li></ul><ul><li>Forms the upper part of the nasal septum </li></ul>
  16. 16. Sutural Bones <ul><li>Also, sutural (AKA Wormian) bones are found in the cranium. </li></ul><ul><li>These bones are tiny, irregularly shaped bones or bone clusters within the sutures. </li></ul>
  17. 20. Facial Bones There are 14 facial bones. The facial skeleton for men is more elongated than for women. Women’s facial skeleton is rounder and less angular.
  18. 21. Mandible <ul><li>Lower jawbone </li></ul><ul><li>U-shaped </li></ul><ul><li>Largest and strongest bone in the face </li></ul><ul><li>Consists of a chin and two rami (branches) </li></ul><ul><li>A large muscle (temporalis) elevates the jaw. </li></ul><ul><li>The lower teeth are anchored into the mandible </li></ul>
  19. 22. Mandible (con’t) <ul><li>The mandibular symphysis is the line of fusion of the mandible in infancy. </li></ul><ul><li>The mandibular foramina allows the lower teeth to have sensation. </li></ul>
  20. 23. Maxilla <ul><li>Upper jaw and central portion of the face </li></ul><ul><li>Anchors the upper teeth </li></ul><ul><li>The palatine processes of the maxilla form 2/3 of the hard palate of the mouth. </li></ul><ul><li>The frontal processes form part of the bridge of the nose </li></ul>
  21. 24. Other facial bones… <ul><li>Zygomatic bones – cheek bones </li></ul><ul><li>Nasal bones – part of the bridge of the nose </li></ul><ul><li>Lacrimal bones – house lacrimal sac (tear duct) </li></ul><ul><li>Palatine bones – palates </li></ul><ul><li>Vomer – nasal septum </li></ul>
  22. 25. Orbits <ul><li>Bony cavities within which the eyes are encases and cushioned by fatty tissue. </li></ul><ul><li>Also, houses muscles that move eyes and the glands that produce tears. </li></ul><ul><li>Formed by parts of frontal, sphenoid, zygomatic, maxilla, palatine, lacrimal and ethmoid bones. </li></ul>
  23. 26. Nasal Cavity <ul><li>Constructed by bone and hyaline cartilage </li></ul><ul><li>Divided in ½ by nasal septum </li></ul><ul><li>Covered in mucus-secreting mucosa, which moisten and warm the air. </li></ul>
  24. 28. The Vertebral Column (Spine)
  25. 29. Vertebral Column <ul><li>Formed from 26 irregular bones connected so that it is flexible and curved. </li></ul><ul><li>Extends from skull to pelvis. </li></ul><ul><li>Surrounds and protects spinal cord </li></ul><ul><li>Provides attachment points for ribs and back muscles. </li></ul><ul><li>As a fetus and infant, we had 33 separate bones. 9 bones fused with age, forming the sacrum and coccyx. </li></ul><ul><li>Each bone is a vertebrae. There are 24 in an adult’s spine. </li></ul>
  26. 30. Division & Curvature of Spine <ul><li>~28 inches long in an average adult </li></ul><ul><li>Has 5 major divisions </li></ul><ul><li>All humans have the same number of cervical vertebrae. However, there is a variation in the number for the rest of the vertebrae in 5% of humans in other regions. </li></ul><ul><li>There are 4 curvatures, giving it a sinusoid (“S”) shape, which increases flexibility. </li></ul>
  27. 31. Divisions of the Spine <ul><li>Cervical vertebrae – 7 vertebrae of the neck </li></ul><ul><li>Thoracic vertebrae – next 12 vertebrae </li></ul><ul><li>Lumbar vertebrae – 5 vertebrae supporting the lower back </li></ul><ul><li>Sacrum – hip bones and pelvis </li></ul><ul><li>Coccyx – tiny end of spine </li></ul>
  28. 33. Homeostatic Imbalances of the Spine <ul><li>Scoliosis: abnormal curvature of the spine usually in thoracic region, commonly in females </li></ul>
  29. 34. <ul><li>Kyphosis: hunchback found in older adults </li></ul><ul><li>Lordosis: swayback; exaggerated lumbar curvature </li></ul>
  30. 35. Ligaments of the Spine <ul><li>Cables that cause the spine to be upright </li></ul><ul><li>Major supporting ligaments are anterior and posterior, running down the front and back of the spine. They prevent hyperextension and hyperflexion. </li></ul><ul><li>Short ligaments connect each vertebrae to those above and below. </li></ul>
  31. 36. Intervertebral disks <ul><li>Cushion like pads </li></ul><ul><li>Composed of 2 parts: </li></ul><ul><ul><li>Nucleus pulposus: “rubber ball;” elastic and compressible </li></ul></ul><ul><ul><li>Annulus fibrosus: girdle for the nuclus pulposus, holds vertebrae together and resists tention </li></ul></ul><ul><li>Act as shock absorbers </li></ul><ul><li>Account for ~25% of the spine’s length </li></ul>
  32. 37. Discs (con’t) <ul><li>Flatten during the day  taller in the morning </li></ul><ul><li>Herniated (prolapsed) disc: annulus fibrosus ruptures, allowing the nucleus pulposus to protrude </li></ul>
  33. 38. General Structure of Vertebrae <ul><li>Each vertebrae consists of a body (centrum) anteriorly and a vertebral arch posteriorly </li></ul><ul><li>Body and arch enclose an opening called verebral foramen. </li></ul><ul><li>Stacked foramen form a canal for the spinal cord to pass. </li></ul>
  34. 40. Vertebral Column Characteristics
  35. 41. Cervical Vertebrae <ul><li>C 1 – C 7 </li></ul><ul><li>Smallest and lightest </li></ul><ul><li>C 1 & C 2 </li></ul><ul><ul><li>Have no discs in between them </li></ul></ul><ul><ul><li>Allow the head to rotate </li></ul></ul>
  36. 42. Thoracic Vertebrae <ul><li>All articulate with ribs </li></ul><ul><li>T 1 – T 12 </li></ul><ul><li>Have a long spinous process that points down </li></ul>
  37. 43. Lumbar Vertebrae <ul><li>“ Small of the Back” </li></ul><ul><li>Receives the most stress </li></ul><ul><li>L 1 – L 5 </li></ul><ul><li>Have short, flat spinous processes that are hatchet-shaped – can be seen when bent over </li></ul>
  38. 44. Sacrum <ul><li>Five vertebrae that are fused </li></ul><ul><li>S 1 – S 5 </li></ul><ul><li>The remainder of the vertebral column continues as the sacral column </li></ul><ul><li>Sacral hiatus: enlarged opening where the 5 th vertebrae fails to fuse completely </li></ul>
  39. 45. Coccyx <ul><li>“Tailbone” </li></ul><ul><li>Small triangular bone </li></ul><ul><li>3-5 vertebrae fused together </li></ul><ul><li>Nearly useless – gives slight support for the pelvic organs </li></ul>
  40. 46. The Bony Thorax
  41. 48. Bony Thorax <ul><li>Chest and bony underpinnings </li></ul><ul><li>Include thoracic vertebrae, ribs, sternum, and costal cartilage </li></ul><ul><li>Protects heart, lungs, and major blood vessels </li></ul><ul><li>Supports shoulders and limbs </li></ul><ul><li>Provides attachment for muscles of the neck, back, chest, and shoulders </li></ul><ul><li>Intercostal spaces: space between ribs, occupied by intercostal muscles; responsible for the lift and depression of the thorax during breathing </li></ul>
  42. 49. Sternum <ul><li>“Breastbone” </li></ul><ul><li>Anterior midline of thorax </li></ul><ul><li>Resembles a dagger </li></ul><ul><li>Flat bone </li></ul><ul><li>~6 inches long </li></ul>
  43. 50. 3 Parts that make up the Sternum <ul><li>Manubrium: superior portion; shaped like a necktie knot </li></ul><ul><li>Body: midportion; forms the bulk and the 2 nd – 7 th ribs attach </li></ul><ul><li>Xiphoid process: forms inferior end; it is hyaline cartilage of youth, but bone in adult (attachment point of abdominal muscles) </li></ul>
  44. 51. Ribs
  45. 52. Ribs <ul><li>12 pair of ribs </li></ul><ul><li>All ribs attach to the thoracic vertebrae </li></ul><ul><li>Divided into two types of ribs </li></ul><ul><ul><li>True </li></ul></ul><ul><ul><li>False </li></ul></ul><ul><li>Ribs increase in length from pair 1 – pair 7; then, they decrease from pair 8 – pair 12 </li></ul><ul><li>Typical ribs are bowed flat bones. </li></ul>
  46. 53. True Ribs <ul><li>The superior 7 pairs of ribs are true ribs. </li></ul><ul><li>They are known as vertebrosternal ribs, because they attach both to the spinal column and the sternum. </li></ul>
  47. 54. False Ribs <ul><li>The remaining 5 pairs of ribs are false ribs. </li></ul><ul><li>Pairs 8-10 attach indirectly to the sternum – vertebrochondral ribs </li></ul><ul><li>Pairs 11 & 12 do not attach at all to the sternum – floating ribs </li></ul>
  48. 56. Appendicular Skeleton <ul><li>Bones of the limbs and their girdles </li></ul><ul><li>Enable us to carry out movement </li></ul>
  49. 57. Pectoral (Shoulder) Girdle <ul><li>Consists of the clavicle and scapula </li></ul><ul><li>Attach the upper limbs to the axial skeleton </li></ul><ul><li>Provide attachment for many muscles </li></ul><ul><li>Very light and because the scapula is unattached and the socket is shallow, it allows a lot of mobility. </li></ul>
  50. 58. Clavicle (Collar Bone) <ul><li>Slender, curved long bone </li></ul><ul><li>Cone shaped at the end and attaches to sternum </li></ul><ul><li>Flat at the end that attaches to the shoulder blades </li></ul><ul><li>Act as braces, holding arms and shoulder blades out laterally </li></ul><ul><li>Not very strong; easily fractured and sensitive </li></ul>
  51. 59. Scapula <ul><li>Shoulder blade </li></ul><ul><li>Thin and triangular flat bones </li></ul><ul><li>Dorsal side of the ribcage </li></ul>
  52. 60. The Upper Limb Consists of 30 bones.
  53. 61. Arm <ul><li>Humerus: sole bone of the arm </li></ul><ul><ul><li>Long bone </li></ul></ul><ul><ul><li>Largest and longest of upper limb </li></ul></ul><ul><ul><li>Connects with scapulae and forearm </li></ul></ul><ul><li>Only part of the upper limb between the shoulder and elbow </li></ul>
  54. 62. Forearm <ul><li>Ulna </li></ul><ul><ul><li>Longer bone of forearm </li></ul></ul><ul><ul><li>Found medial when standing anatomically correct </li></ul></ul><ul><li>Radius </li></ul><ul><ul><li>Anchor bicep muscle </li></ul></ul><ul><ul><li>When radius moves, the hand moves. </li></ul></ul>
  55. 63. Hand
  56. 64. Carpus <ul><li>Wrist </li></ul><ul><li>Consists of 8 marble-sized short bones (carpals) </li></ul><ul><li>United by ligaments </li></ul><ul><li>Carpal Tunnel Syndrome </li></ul><ul><ul><li>Overuse and inflammation of tendons, causes swelling </li></ul></ul><ul><ul><li>Compresses nerves </li></ul></ul><ul><ul><li>Causes numbness </li></ul></ul>
  57. 65. Metacarpus <ul><li>Palm </li></ul><ul><li>Bones radiate from wrist (metacarpals) </li></ul><ul><li>Numbered 1-5 </li></ul><ul><li>Heads of bones are knuckles </li></ul><ul><li>Metacarpal 1 is the thumb and is the shortest and most mobile </li></ul>
  58. 66. Phalanges <ul><li>Fingers, AKA digits </li></ul><ul><li>Numbered 1-5 </li></ul><ul><li>Each hand has 14 mini long bones </li></ul><ul><li>Each finger has 3 phalanges: distal, middle, and proximal </li></ul><ul><li>Thumb has only 2 phalanges (no middle) </li></ul>
  59. 68. Pelvic (Hip) Girdle <ul><li>Attaches lower limbs to axial skeleton </li></ul><ul><li>Supports and protects pelvic organs </li></ul><ul><li>Formed by a pair of hip bones, consisting of 3 separate bones: </li></ul><ul><ul><li>Ilium </li></ul></ul><ul><ul><li>Ischium </li></ul></ul><ul><ul><li>Pubis </li></ul></ul>
  60. 69. Ilium <ul><li>Large, flaring bone </li></ul><ul><li>Consists of a body and winglike portion called ala (singular) or alae (plural) </li></ul><ul><li>When resting your hands on your hips, you are resting on the thickened superior margins of alae. </li></ul>
  61. 70. Ischium <ul><li>Posteroinferior part of the hip </li></ul><ul><li>L-shaped </li></ul><ul><li>When we sit, the weight is entirely on the ischium. </li></ul>
  62. 71. Pubis <ul><li>Anterior portion of the hip </li></ul><ul><li>Bladder rests on it </li></ul><ul><li>V-shaped </li></ul><ul><li>The pubic arch helps to differentiate males from females. </li></ul>
  63. 73. The Lower Limb The thicker and stronger bones due to the weight and stress on them.
  64. 74. Thigh <ul><li>Femur: single bone of the thigh </li></ul><ul><ul><li>Largest and longest bone </li></ul></ul><ul><ul><li>Strongest bone </li></ul></ul><ul><ul><li>~ ¼ of a person’s height </li></ul></ul>
  65. 75. Leg <ul><li>Tibia </li></ul><ul><ul><li>Shin bone </li></ul></ul><ul><ul><li>2 nd largest and strongest bone </li></ul></ul><ul><ul><li>Medial surface not covered by muscles </li></ul></ul><ul><li>Fibula </li></ul><ul><ul><li>Sticklike bone with expanded ends </li></ul></ul><ul><ul><li>Forms lateral ankle bulge </li></ul></ul><ul><ul><li>Doesn’t bear weight, but it is attachment point for many muscles. </li></ul></ul>
  66. 76. Foot Supports body weight Propels us forward when we walk.
  67. 77. Tarsus <ul><li>7 Tarsal bones </li></ul><ul><li>Weight is carried by the talus (ankle) and the calcaneus (heel). </li></ul><ul><li>Achilles (calcaneal) tendon attaches to calcaneus. </li></ul>
  68. 78. Metatarsus <ul><li>5 Small long (metatarsal) bones </li></ul><ul><li>Numbered 1-5 </li></ul><ul><li>Enlarged head of 1 st metatarsal forms “ball” of foot </li></ul>
  69. 79. Phalanges (Toes) <ul><li>14 phalanges </li></ul><ul><li>Smaller than fingers </li></ul><ul><li>Less maneuverable </li></ul>
  70. 81. Arches <ul><li>Distribute weight evenly between ball and heel of foot </li></ul><ul><li>Gives foot great strength and mobility </li></ul>