The Third Lumbar Vertebra

Continuing upwards it is now time for me to write about the third lumbar segment. I will continue to show that most lesions within the lumbar spine are group lesions and highlight that as the reason for the pelvis being the first adjustment.

The third lumbar vertebra is larger than the second and is fairly typical in terms of general structure. As with other lumbar segments the primary movement is flexion and extension in the sagittal plane. The facets are oriented medially and limit rotation and side-bending – they happen although it is important to remember that they are limited mechanically.

The nerves associated with the third lumbar segment are: the femoral nerve/anterior crural nerve (L2-L4), the obturator nerve (L2-L4), the lateral femoral cutaneous nerve (L1-L3), as well as sending sympathetic fibers to the aortic and hypogastric plexuses.

The muscles that Marion Clark makes important note of as being associated with the third lumbar segment are multifidus and psoas major. Both multifidus and psoas major have the ability to cause a lesion to the third lumbar segment as well as to experience altered function as a result of a lesion in the third lumbar.

A very important point to note is that the femoral nerve passes THROUGH the psoas muscle. Due to the fact that the femoral nerve actually lives inside of the psoas there is all kinds of possibilities for a mechanical lesion to the femoral nerve and related lumbar segments as it is attached to the transverse processes of (depending on the source) T12-L5 as well as the intervertebral discs of the same segments. It should be clear through the attachment sites of the psoas muscle that it can cause a lot of trouble if there is a lesion in the segments that feed the femoral nerve (L2-L4)! Now it should be clear that ANY lesion that involves the pelvis will affect the iliopsoas (functionally the psoas major, psoas minor, and the iliacus are one muscle) will cause a group lesion to the pelvis, the lumbar spine and the thoraco-lumbar junction! The first adjustment must be to the pelvis as it requires the use of the iliopsoas to correct the pelvis and, in doing so, the tension is relieved from the femoral nerve and the base of the body becomes level so that all other adjustments may occur. By adjusting the pelvis the Osteopathic Operator will make an adjustment all the way up to the thoraco-lumbar junction if they know what they are doing!

Enough yelling about pelvic adjustments…Clark makes it clear that most pain in the lower limbs is related to the passage of the femoral nerve through the psoas. Clark also provides much information on affects to the pelvic viscera as a result of a lesion of the third lumbar segment. I will keep it simple and say that the majority of the pelvic viscera will either be excited (sympathetically charged) or inhibited (parasympathetically charged) depending on the type of lesion found in the third lumbar segment.

The take home message from all of this? The psoas muscle is of MAJOR importance to the entire body from an Osteopathic perspective. There are so many implications to neurology, mechanical and neurological implications to viscera, as well as mechanical and neurological implications to fluid dynamics throughout the entire lower body.


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