Biol 2304 chapter 7 2

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The Axial skeleton: notes

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Biol 2304 chapter 7 2

  1. 1. CHAPTER 7 “The Axial Skeleton #2” Course objectives:Define and identify the bones of the axial skeleton
  2. 2. Vertebral column composed of 26 irregular bones. These bones provide a solid support structure, but are also remarkably flexible.
  3. 3. Regions of the Vertebral Column – Cervical − neck region 7 vertebrae – Thoracic – thorax region 12 vertebrae – Lumbar – lower back 5 vertebrae – Sacral – low, low back 1 vertebrae (5 fused) – Coccygeal – tail bone 1 vertebrae (4 fused)
  4. 4. Spinal Curvature Thoracic and sacral are concave (i.e. backward) Primary curves since they developed first. Cervical and lumbar curves are convex (i.e. forward) and secondary curves.
  5. 5. Vertebral column
  6. 6. Vertebrae Individual vertebrae are found in the cervical, thoracic and lumbar regions of the vertebral column. There are significant differences between the vertebrae in each of these regions that you should know.
  7. 7. Cervical vertebrae – C1- C7 Body is oval; spinous process is short (except C-7) and sometimes split; Large vertebral foramen Transverse foramen for vertebral artery to brainstem. C1 is Atlas articulates (atlanto-occipital joint) with occipital bone of skull -allows “yes” motion of head C2 is Axis characterized by peg-like process called “dens” or odontoid process which interlocks with atlas (atlanto-axial joint) -allows sideward rotation or “no” motion of head.
  8. 8. Cervical VertebraeAtlasAxis
  9. 9. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Atlanto/axial joint Atlas (C1vertebra) Articular facet of dens Dens Transverse ligament Axis C2 vertebrae)(c) Axis and atlas, posterosuperior view
  10. 10. Cervical Vertebrae
  11. 11. Thoracic vertebrae T1- T12 Body is roughly heart shaped Demifacets for rib articulation Vertebral foramen are circular Spinous process long and points inferiorly The thoracic vertebra look like a giraffe’s head when viewed from the lateral view!
  12. 12. Thoracic vertebrae T1- T12
  13. 13. Lumbar Vertebrae L1-L5 Pedicles and laminae are short and thicker Spinous processes are short, flat and hatchet shaped Vertebral foramen is triangular Inferior and superior processes lock the adlacent vertebrae together for strength and stability. The lumbar vertebra look like a Moose’s head!
  14. 14. Lumbar Vertebrae L1-L5
  15. 15. Sacral Vertebrae S1-S5 Sacral vertebrae consists of 5 fused vertebrae fully fused by 30 years of age Women sacrum is shorter, wider and more curved Connects the spine to the pelvic girdle at the sacroiliac joint. Sacral canal is continuation of vertebral canal.
  16. 16. Sacrum and CoccyxAnt. ViewPost view
  17. 17. Coccyx Vertebrae Co1-Co4 Coccyx is Greek for “cuckoo” Consists of 4 fused vertebrae Fuse between 20 and 30 years Tailbone is vestige of tail - Men it points anteriorly - Women it points inferiorly
  18. 18. Cervical and Thoracic vertebrae
  19. 19. Lumbar vertebrae
  20. 20. Additional structures of the vertebral column Intervertebral discs Present between all vertebrae C2- L5/S1; Composed of fibro cartilage Two regions of disc: - nucleus pulposis – central core of disc - annulus fibrosis - outer covering of fibro cartilage Function: -discs permit various movements -provide shock absorbing functions for vertebral column
  21. 21. Vertebra and vertebral disc
  22. 22. Herniated Intervertebral discs Spinal cordDorsal root ganglion
  23. 23. Vertebral Ligaments(1). Anterior and posterior longitudinal ligaments hold vertebral column together along with trunk skeletal muscles -prevent hyper-extension and hyper-flexion of the vertebral column.(2). Shorter ligaments connect adjoining vertebrae together. -There are 3 of these ligaments the ligamentum flavum, the supraspinous ligaments and the interspinous ligaments.
  24. 24. Vertebral Ligaments
  25. 25. Bony Thorax Consists of ribs attached to the vertebral column and sternum True ribs R1-R7 attach directly to sternum False ribs R8-R10 attach indirectly Two floating ribs R11 & R12 The Sternum consisting of: - manubrium - body - Xiphoid process
  26. 26. Bony Thorax
  27. 27. Ribs1. true ribs – the first (superiormost) seven pairs of ribs R1-R7 are directly connected to the sternum via costal cartilage. - are called vertebrosternal ribs.2. false ribs – the remaining five pairs of ribs. There are two types of false ribs.  vertebrochondral ribs -- rib pairs #8, #9, and #10 are connected by a single band of costal cartilage to the inferior portion of the sternum. Unlike the first seven pairs of ribs they do not have their own individual attachments.  floating or vertebral ribs – rib pairs #11 and #12 are connected only to the vertebral column, they have no anterior connection to the skeleton.
  28. 28. All ribs articulate with vertebral column. The head of the rib articulates at a demifacet on the body of the vertebrae, while the tubercle of the rib articulates at a facet on the transverse process.
  29. 29. Sternum “breast plate” Anterior central portion of thorax Only bony attachment of axial skeleton to appendicular skeleton via clavicle. Consists of Manubrium, Body and Xiphoid process Key landmarks: calvicular notches, jugular notch “suprasternal notch”, sternal angle.
  30. 30. SternumThe sternal foramen is an anomaly and occurs in ~ 4-10% of the population. It can be mistaken for a bullet puncture in cases of traumatic death.
  31. 31. Hyoid bone Lies inferior to the mandible Is not attached to skeleton by bony means Helps movement of base of tongue
  32. 32. Hyoid bone

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