Read Annie Carpenter's response:
It is truly amazing how different we all are! Each of us has an individual expression of the human body, which is to be celebrated and yet is, at times, frustrating.
There are many variations of the lumbar spine, or lower back, which usually consists of five thick vertebrae just above the sacrum of the pelvis. Typically, this section of the spine curves anteriorly, or in toward the front of the body. Your student may have a flattening or a reversal of this curve, creating the pressure she feels and a more visible bony presence. Or she may simply have a pronounced shape to the spinous processes, which are the parts of each vertebra that point backward and are often palpable. If your student has pain or numbness, please encourage her to see her physician.
One simple way to help your student is to give plenty of padding for comfort. Perhaps supine poses are not the best choice for her. For example, she can practice Salambhasana (Locust Pose) or Bhujangasana (Cobra Pose) while her fellow students are practicing Setu Bandha Sarvangasana (Bridge Pose). These backbends will help reintroduce the anterior curve of the lumbar spine. Have her emphasize the breath as she moves; the inhalations will guide her in creating space between the vertebrae, and as she exhales, she may find a bit more movement is possible.
But perhaps more importantly, this is a reminder for all of us that we are remarkable in our differences, and that rather than try to fit ourselves into yoga, we should adjust the yoga to fit our individual shapes and needs. Ultimately, this is a lesson in samtosha, or contentment. Our practice reminds us of who we are, what is easy and what is not; and that it is our work to see clearly, pause as needed, and accept what is, unconditionally.