The appendicular skeleton includes two very important bones that work together to perform many tasks. These are the knees and pelvic girdle. The pelvic girdle’s purpose is to serve as attachment points for the lower limbs and some of the axial skeleton (Openstax College, 2013). This one large bone structure that is resistant to movement, provides stability and is formed by the hip bone. The hip bone consists of the ilium, isicum, and pubis which attach to the pelvis and the coccyx. In the male and female pelvis there are a few differences that affect body size and function. In females the pelvis is significantly wider to account for childbirth. They also have a larger subpubic angle with their pelvis less curved and more oval shaped.

Moving downward we encounter the knee. This is an interesting part of the body as it is not a bone itself but an intersection of several bones, the femur, tibia, and patella, and joints. The femur’s lateral epicondyle and medial epicondyle, the tibia’s medial condyle and lateral condyle, and the patella make up the knee (Openstax College, 2013). An important feature of the knee is the Q-angle which is the measure of how far the femur is angled laterally away from vertical. During the knee’s extension the quadriceps femoris pulls the patella both superiorly and laterally. In women the lateral pull is greater because of the larger Q-angle which places more stress on the knee itself.

 These bones develop like most other bones in the body. Bone development is a long process and starts in the womb. They are first mostly hyaline cartilage, but then begin to build up a calcified matrix which becomes the ossification center. An artery provides the nutrients needed for continued growth in the medullary cavity. A second ossification site is established at the end of the bone that will eventually become the epiphysis. More arteries bring nutrients to this site and turn the previous hyaline cartilage into articular cartilage and spongy bone. The epiphyseal plate is where more growth will happen over the years.

 I am covering the objective of how bones are hormonally regulated. All of this growth is regulated by hormones, some including the growth hormone and estrogen. Estrogen, which has a biphasic effect is critical for bone growth in both sexes (Emmanuel, et. Al. 2021). Throughout puberty there are high levels of E2, one of the four kinds of estrogen, to promote growth and maintenance. However, E2 is also used to close the epiphyseal plates to stop growth. Testosterone is used as well to stimulate periosteal growth (Emmanuel, et al. 2021). One of the biggest influencers, however, is the growth hormone or GH. By triggering chondrocyte proliferation, it can increase calcium retention. The parathyroid hormone encourages osteoclast work which breaks down the bone to help maintain it.

Bone injuries and diseases come about for many reasons. One of these which I am going to discuss directly affects the knees. It is called Osgood-Schlatter’s disease. Being an adolescent disease, it affects the growth plates and causes pain, swelling, and irritation. The reason this happens is because the plates are made of cartilage before puberty hits, which are never as strong as actual bone(Unknown, 2023). If the growth plate by the patellar tendon where it attaches to the tibia endures a lot of stress and repeated extension, then tissue around that area begins to hurt and swell. By rest and less stress put upon the knee, the pain and swelling stop. The majority of the time Osgood-Schlatter disease will go away as the child grows up. Because bone is stronger and less prone to irritation, often the problems will go away.  The video demonstrates exercises meant to heal and strengthen the muscles and joints surrounding the knee to help prevent more injuries or any at all.


Openstax College, (2013). Anatomy and Physiology. Rice University  

Emmanuelle, N. E., Marie-Cécile, V., Florence, T., Jean-François, A., Françoise, L., Coralie, F., & Alexia, V. (2021). Critical Role of Estrogens on Bone Homeostasis in Both Male and Female: From Physiology to Medical Implications. International journal of molecular sciences22(4), 1568.

Unknown (2023). Osgood-Schlatter Disease. John Hopkins Medicine

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One Comment

  1. Isabel clearly explains how bones develop hormonally, the stages of bone growth from conception to adulthood, a description of the appendicular. She also included information about Osgood-Schlatter’s disease which I found very interesting because my family have all suffered with varying degrees of Osgood-Schlatter’s with my father and I having the worst symptoms. It was interesting to see a perspective from outside of the family and it was not covered in the textbook. Other than physical therapy and rest, are there ways to heal this or manage the symptoms? How much of this disease affects the pelvic girdle compared to the knees? My only symptoms were in my knees so I am very curious what other places can be affected severely. E2 also induces the closing of the epiphyseal plates as well as growth, would a reduction of this and an increase in growth hormones make someone taller? A higher Q angle is associated with decreased knee strength and power output and injuries as stated in the video. However, injuries can be prevented by increasing the strength of the quadricep through exercises as shown in the video. Other important muscles to strengthen for knee stability are the gluteus medius and the gluteus maximus because they help stabilize the hip and knee when walking. When the gluteus medius lacks strength, the hip over reaches on the weight bearing leg and causes tension down the quadriceps and on the tendons like the ACL.

    Tyler Coniam

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