Muscular Case Study 3*

The Case of the Unlucky Hiker

 

Emily, a twenty-four year old Asian-American graduate student in animal behavior, spends her free time hiking in the mountains around her home observing the behavior of various animals in preparation for her graduate work. One afternoon, Emily decides to spend her time hiking on less frequented trails in hopes of working on walking quietly while carefully observing the area around her. The day is warm and Emily is careful to drink frequently to minimize her chances of becoming dehydrated. Also, she snacks while hiking to maintain adequate blood glucose. As she rounds a bend in the trail, Emily notices a small herd of deer in the ravine below her and decides to try to move closer to them. After carefully checking the wind she starts to slowly move down the slope toward an overhanging ledge she noticed about halfway down. As she approaches the ledge, Emily looses her footing and begins to slide down the side of the ravine. She tries to catch herself at the ledge, but falls over the side of the ledge twisting her left knee and landing awkwardly on her left side. She continues to slide down the slope and finally comes to a stop at the edge of a grove of fir trees. While she does not loose consciousness, Emily is stunned and it takes her a few minutes to regain her composure. The first thing she notices is that her left leg is at an awkward angle and her left knee is very painful. When she tries to get up, she experiences pain in her left knee.

 

Emily feels certain that she has not sustained any injuries to her arms, shoulders, ribs or abdominal organs. Her right leg and shin seem to be "normal", however her left knee appears to be injured and is swelling quite rapidly. Emily replies that she thinks she may have injured her left knee and she will wait until help arrives.  She begins to feel chilled, so she puts her jacket on and has something to eat and drink.  Approximately 90 minutes later she hears voices calling to her from above.  A rescue team arrives and their diagnosis concurs with Emily’s and they transport her to the trail and then to the regional hospital.  She tells the emergency room physician that she thought she heard a "popping" sound when she twisted her knee as she started to fall. The results of this examination indicate that Emily has not suffered any major injuries other than torn knee ligaments in her left knee. The emergency room physician immobilizes the leg and calls for an orthopedic consultation regarding her knee. The results of the magnetic resonance image (MRI) of her knee indicate a torn anterior cruciate ligament and medial meniscus. Emily is scheduled for surgery to repair her knee the next day and kept in the hospital overnight for observation.  The next morning the orthopedic surgeon performs arthroscopic surgery on Emily’s left knee.

 

Questions

 

1. Describe motion at the five joints; give an example of each:
-Ball and Socket
-Hinge
-Pivot
-Gliding
-Fixed (immovable)

2. Describe structure of skeletal muscle at sarcomere level.
Explain the Sliding-Filament Mechanism for muscle contraction.

 

3. Why was Emily becoming chilled after her fall? 


4. How does the anatomy of the knee differ from the anatomy of the elbow?

5. How do the cruciate ligaments in the knee aid in maintaining stability of the joint?

6. What is the cause of swelling in Emily’s left knee following the injury?

7. What kind and what are the purposes of the rehabilitation exercises Emily would be expected to complete?


*adapted from McGraw Hill Online Learning Center, Essentials of Anatomy and Physiology,3rd ed.Seely/Stephens/Tate