Yaar… Deliver me Lumbar…

Where, my friend, is this Lumbar Region?

Well, friend… It refers to one of the six regions of the axial skeleton:

  1. the cranial region (skull)
  2. the cervical region (neck)
  3. the thoracic region (chest / upper back)
  4. the lumbar region (abdomen / lower back)
  5. the sacral region (butt)
  6. the coccygeal region (tailbone)

And, it’s a very flexible section of the axial  skeleton (complementary to the appendicular skeleton). For example… In the torso (thorax plus abdomen), the thorax is surrounded by the ribcage; providing a lot of protection for the soft squishy bits (the lungs, the heart, the stomach, spleen, etc.).

axialSkeletonDrawing03

a cool list of human anatomical regions.

But the lumbar is supported and protected by soft tissue. This makes the lumbar more flexible (like the neck), but also more vulnerable.

As with most parts of the musculoskeletal system, the body is always favoring either stability or range of motion (compare the glenohumeral joint to the ilio-femoral / acetabulofemoral joint).

Other cool facts: the lumbar also lends its name to a muscle in that region (quadratus lumborum anyone?). The appendicular skeleton articulates with the axial skeleton at two1 locations: the sacroiliac joint and the sternoclavicular joint2. Last but not least, there’s 80 bones in the axial skeleton, or thereabouts.

Bones of the Axial Skeleton:

  • Skull: 22 (facial bones: 14, cranial bones: 8)
  • Auditory Ossicles: 6
  • Hyoid: 1
  • Cervical: 7 (C1-C7)
  • Thoracic: 12 (T1-T12)
  • Ribs: 24
  • Lumbar: 5 (L1-L5)
  • Sacral: 4 to 5 (S1-S5)
  • Coccygeal: 3 to 5 (CO1-CO5). While the amount of bones can vary from individual to individual, the coccyx has the greatest disparity, from three to five bones, depending on whose tailbone it is.

For more cool anatomical fun, some excellent references are: Netter’s Atlas of Human Anatomy, and Andrew Biel’s Trail Guide to the Body.

Notes:

1 There are actually four discrete locations, but they are bi-laterally symmetrical and taxonomically identical pairs—so there.

2 The only place that the arm bone attaches to the body bone

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