Muscles of the Pelvis

by Sheldon C. Yao, DO

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    00:00 Muscles of the pelvis help to provide support for the contents. So, your pelvic organs kind of sit on top of this pelvic diaphragm. So, the levator ani, the coccygeus here as pictured here. So, all of these kind of form a diaphragm that moves with inhalation/exhalation and helps to support the organs from below. The pelvic wall also has the piriformis muscle that runs from the anterior portion of the sacrum out to the femur. This muscle is really important because sometimes when spasmed it could potentially irritate the sciatic nerve. In fact in some people, the sciatic nerve actually passes through the piriformis muscle and so irritation in the piriformis muscle can irritate the sciatic nerve mimicking neuropathic pain going down the leg, which one might think could be a herniated disc but sometimes it could be from piriformis syndrome. The obturator internis is also another muscle that helps to make that surround the pelvis and the pelvic floor. Muscles of the trunk and lower extremity allow for local motion. You have muscles anteriorly that attach to the pelvis including the rectus abdominus, transverse abdominus, and the internal/external obliques. These muscles kind of come together and help form your core muscles, the cylinder that wraps around all the way to the back and it helps to strengthen and support your lumbar spine and attaches along the pelvis. If you do have overuse or inflammation, sometimes these muscles were attaches to the pubic bone could be inflamed and it could cause pain in the pubic region.

    01:41 Your quadratus lumborum is a really important muscle that attaches along the lumbar spine and also to the 12th rib then attaches along the iliac crest, when activated unilaterally is going to cause side bending and some extension bilaterally. What happens with the quadratus lumborum is if it's inappropriately spasmed it could really contribute to low back pain, pelvic pain. It could cause some dysfunctions and asymmetries of the pelvis itself and also could affect breathing because it could lock down the 12th rib preventing the diaphragm from moving well. The iliopsoas is consistent of 2 different muscles. You have your psoas major and also the illiacus. So the iliac is kind of originates along the rim of the inside border of the innominate, comes down and blends in with psoas major which originates from the anterior portions of the lumbar spine. This muscle comes down and attaches to the femur. It's a really important muscle because it tends to flex the hip and bilaterally flex the spine and this muscle sometimes tends to become more spasmed especially if you move from a crouch or flexed position suddenly to a standing or straight position.

    02:54 Patients may complain about unilateral sharp back pain that radiates down into their groin mimicking kidney stones. So, iliopsoas spasm is something that you should consider when someone has lower back pain and has a history of complaining of difficulty standing up and there is involvement with the hip. You could actually perform a special test called the Thomas test where you see how much the muscle could be stretched in order to see if it's contracted. Muscles of the lower extremity.

    03:23 So you have a lot of different muscles that attach from the pelvis down into the leg. These muscles can potentially cause any asymmetry when spasmed. They could kind of pull the innominate forward or out of place so the rectus femoris has its origins at the AIIS or the anterior inferior iliac spine. You have your sartorius, which originates at the ASIS which is the anterior superior iliac spine. In addition, you have gracilis. The tensor fascia latae a little bit more laterally blending into the IT band or iliotibial band. Again, the iliopsoas muscle, and then you have your adductors that originate from the pubic bone. Of note, the adductors and abductors of the hip sometimes could be activated to help try to treat some of these somatic dysfunctions of the pelvis. So, a lot of times some of the treatments that we utilize utilizes these muscles in order to try to make the asymmetry better and sometimes by treating hypertonic muscles we are able to decrease the cause of what's causing the somatic dysfunctions in the first place. So it's important to kind of really understand where the muscles are located, where they originate from, where they attach and how a spasm muscle here, let's say the rectus femoris, if it's spasmed would cause asymmetry at the pelvis. Looking at the muscles that attach to the pelvis posteriorly along the posterior border of the crest do we have your gluteus muscles. Here you see the adductors attaching and then the biceps femoris which is a major hamstring muscles in the back of the leg which all of these tend to help more with hip extension. But here again, if these muscles are spasmed it may create a different pole causing a shift in the innominate rotations.

    About the Lecture

    The lecture Muscles of the Pelvis by Sheldon C. Yao, DO is from the course Osteopathic Diagnosis of the Pelvic Region. It contains the following chapters:

    • Muscles of the Pelvis
    • Muscles of the Trunk and Lower Extremity

    Included Quiz Questions

    1. Iliococcygeus muscle
    2. Iliacus muscle
    3. Piriformis muscle
    4. Obturator internus muscle
    5. Coccygeus muscle
    1. 12th rib and lumbar spine
    2. Iliac fossa
    3. Lesser trochanter of femur
    4. 9th rib
    5. Thoracic spine
    1. ASIS (Anterior Superior Iliac Spine)
    2. AIIS (Anterior Inferior Iliac Spine)
    3. Iliac crest
    4. Iliac fossa
    5. Pubic bone
    1. Thomas test
    2. Ortolani test
    3. Allis test
    4. Patrick test
    5. Ober test

    Author of lecture Muscles of the Pelvis

     Sheldon C. Yao, DO

    Sheldon C. Yao, DO

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