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Class Notes: Human Osteology

Friday: September 30, 2011

Week 4: Spine and Thorax & Review


 The human body has 24 vertebrae:

  • 7 cervical
  • 12 thoracic
  • 5 lumbar
There are two kinds of curves that create the “S-curve”: lordosis (a ventral curve, employed by  the cervical verts and the lumbar verts) and kyphosis (a dorsal curve, employed by the thoracic verts and sacrum).
Some vertebrae have special identifying features:
  • C1, otherwise known as Atlas, articulates with the skull, allowing us to shake our heads “yes”
  • C2, otherwise known as Axis, articulates specially with C1 via the Odontoid, allowing us to shake our heads “no”
  • C7 is the bump you can feel at the bottom of your neck, and it transitions into the thoracic vertebrae
  • T1 is also transitional between cervical and thoracic, but unlike the cervical verts, all other verts lack transverse foramina
  • T10-T12 transition into lumbar verts, but each still maintains a costal facet which articulates with a rib
  • L5 is transitional to the sacrum (sometimes it even becomes fused with the sacrum)
We also covered the sacrum and coccyx which are each important for muscle attachment. Between each vertebra is an intervertebral disk. This is made of annulus fibrosis, which surrounds the nucleus pulposis, a remnant of the notochord. When a person has a slipped disk, the disk itself does not slip, but the nucleus pulposis is no longer centered. It is estimated that this soft tissue accounts for almost 25% of our vertebral height.

We have twelve pairs of ribs, men and women alike. The first six are sometimes called “true ribs” because they each have a cartilaginous connection to the sternum. Ribs 7 through 10 are sometimes referred to “false ribs” because their cartilaginous connection is shared between them. Ribs 11 and 12 are “floating ribs” because they lack this connection to the sternum.

A sternum has three parts, though these often fuse. The top is called a manubrium. If you have ever seen the movie The English Patient, he referred to the supersternal notch, which is the area we call a jugular notch, between the clavicular notches. The body of the sternum is sometimes referred to as the corpus sterni, or sternabrae. The bottom tip of it is the xiphoid process.


 We had lab time to study for our test. Anna and I spent the entire evening there (much like Tuesday) to go over fragments. I have trouble siding the sphenoid. That bone is not my friend.


We had the first test of the semester. 50 written questions, but an additional essay and diagram for the grad students. Then we had 50 practical questions, plus 10 extra hard grad student questions, and an optional 10 question quiz. I got done with both parts early and with time to go over each question to be absolutely sure. There were a few I couldn’t be confident about but overall I think I did alright. My main issue is still balancing time. Two classes demand a lot of time for reading. This class demands a lot of extra lab time. And then I have the Dental Microwear Project to work on also, not to mention commuting and saving time for “weekend husband”. As the semester draws on, I am finally getting the feeling of caught up, so by the end of the semester, I ought to be rocking it.


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One remark!

  1. I was getting concerned about your work…had not heard from you this month…then today here it is..very interesting. Maybe the bones in a back yard could have been in our area? Sounds like you are making us proud…Keep it up. Be sure the food is fresh …if you accept it…
    Enjoy the fall colors too. Keep up the good work. We knew you would do very good on ;your pesentation

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