Structure and Function of the Musculoskeletal System

Jennifer belongs to a women’s rugby team. At 23 years old, she has been playing for five years and trains daily to keep up her strength and stamina. During one game, she was injured. Unable to walk, she was carried off the field supported by her coach and an athletic therapist. At the hospital, after an examination and MRI of her right knee, she was given her diagnosis. Jennifer suffered what is often termed the “O’Donoghue triad”: a ruptured medial collateral ligament, a ruptured anterior cruciate ligament, and tear of the medial meniscus.

1. Jennifer’s injury involved the complete tearing of two ligaments. What are the similarities and differences between the anatomy and function of ligaments and tendons?
2. Jennifer’s rehabilitation will include techniques that will increase her joint proprioception. What is proprioception, and what will occur if this neural function is not restored?
3. The knee joint exemplifies a diarthrodial joint. What are the anatomy of the synovial membrane and the importance of synovial fluid in such a joint?

Case Study 2

Disorders of Musculoskeletal Function: Trauma, Infection, Neoplasms

Marvin is a healthy, active 36-year-old who belongs to a martial arts club. Once a week he takes lessons in Judo, and on the weekends, he participates in local competitions. At his last competition, Marvin was paired with a skilled participant from another club. His rival threw him to the mats, and as Marvin struggled, came down hard to pin him down. Marvin heard a snap, followed by instant pain in his left forearm. Radiographs at the local hospital confirmed he suffered a transverse fracture of the distal aspect of his left ulna.

1. What are the typical signs and symptoms of a fracture? Why shortly after the injury does the pain temporarily subside?
2. How does a hematoma form, and what function does it serve in the process of healing a fracture?
3. Marvin was told he would be seeing a physiotherapist as his healing progressed. What are the muscular and joint changes that occur during immobilization and the ways Marvin and his physiotherapist can work to address these changes?

Case Study 3

Disorders of Musculoskeletal Function: Developmental and Metabolic Disorders

Mandy is a 16-year-old competitive figure skater who practices several hours a day with her coach at the skating arena. Because of her extremely active lifestyle and restricted diet to maintain her athletic physique, she experiences ongoing amenorrhea. One day during practice, she landed a jump and fell to the ice in pain. Her left foot swelled up almost immediately, making it difficult for her coach to remove the skate. At the hospital, radiographs revealed a fracture of the fifth metatarsal bone and general radiolucency of all the bones in her foot. A follow-up DXA revealed a bone mass of 2.7 standard deviations below mean.

1. What is the etiology of Mandy’s premature osteoporosis, and how her condition is thought to contribute to a decrease in bone density?
2. Knowing what you do about bone mineralization, why does a deficiency of estrogen in women lead to osteoporotic change?
3. Osteoporosis and osteomalacia both involve abnormal bone mineralization. What are the general macroscopic differences of these two conditions?

Case Study 4