December 17: Last day of anatomy lecture was rather memorable. Dr. Stern saved the best live show for the finale – “Gait Disorders”
Superior gluteal nerve & the Trendelenburg gait
The gluteus medius and minimus are thigh abductors, thus preventing the opposite thigh from dropping inwards during the support phase of gait. For superior gluteal nerve damage to the gluteus medius and minimus, Dr. Stern demonstrated a bilateral Trendelenburg gait. If you stand on the affected leg, the opposite pelvis drops; to compensate, the trunk laterally flexes to the weak, unsupported side. If there’s a bilateral damage, you look like you’re swaying some sexy hips for Project Runway.
Dr. Stern flattered the class with a caveat: “You will see a case of a person with bilateral Trendelenburg gait. I’m going to show you the bilateral Trendelenburg. But you have to promise not to fall in love with me.” [class chuckles] And then he goes on to pop his pelvis for an anatomy runway show =D I wish I could post the video lecture, but it’s not for public viewing outside of the medical school.
My dad walks with a limp, so I believe he has a Trendeleburg gait. He had polio when he was a child, and he suffered nerve damage to his upper thigh region. His whole left thigh is atrophied and practically useless, so I think multiple muscles are affected. One day, I had my dad walk back and forth for me in the cold, but I could not accurately diagnose the Trendelenburg gait because his clothes were too baggy. The Trendelenburg test asks the patient to stand on one leg and see if he or she drops the opposite hip. For my dad, he cannot stand on one foot without tipping, so that may be a “positive” test. I did not want to be mean and push his hand off my chair when I asked him to do it. That way, I’d get a definitive result AND be a cruddy daughter.
I do believe he has inferior gluteal nerve damage because he cannot walk up the stairs without support. That means, he has paralyzed gluteus maximus, the ‘ass muscle,’ in which he cannot properly extend his thigh. Normally, the gluteus maximus has a small role in the beginning of support phase in gait, controlling for the tendency of the trunk to jack-knife forward at heel strike. When he walks, I’ve been noting a slight backward lean to compensate for the loss.
Sciatic nerve and the Buttocks
The sciatic nerve looks like a huge, white bundle running down the posterior compartment of the thigh. As my professor terms it the “phony nerve” because it’s really 2 nerves running together like Hansel and Gretel. The common peroneal and tibial nerve branch near the back nook of the knee, adorably named the ‘popliteal’ fossa. The sciatic primarily innervates the hamstrings (long head of biceps femoris, semitendinosus, semimembranosus), producing knee flexion and thigh extension.
The sciatic nerve can be damaged in the gluteal region, commonly known as the “ass,” in rather compromising positions.
Dr. Stern: “My wife kills me when I mention this. But, you know, I like to sit and do crossword puzzles… I urge you to do it sometime…. You will feel it when you start to get up. You will feel pins and needles all along the distribution on the sole of your foot and most of your lower leg and you will walk all wobbly.” [professor wobbles forward]… “It’s worth experiencing.”
(2) Prolonged sitting on a thick wallet, what I call the “fat wallet syndrome.”
Dr. Stern: “It’s going to be a problem in years to come… when you become physicians.”
(3) bicycling, cello playing, anything that numbs the butt
“Ohm” the Peroneal nerve
Common peroneal nerve can be damaged easily because it runs laterally down the lower leg, after it parts from the sciatic nerve at the popliteal fossa. External pressure from plaster casts, lithotomy support, and the lotus position can compress the nerve.
(1) I’ve never had a broken leg, so plaster casts have not been a big deal. But if you’ve broken (or will break) a leg, just remember your common peroneal is at risk when your leg is taking a little plaster vacation.
(2) What are lithotomy positions? Well, it’s mainly for pelvic and lower abdomen surgeries. It involves laying supine, knees bent, and legs up high and spread apart in stirrups, not too much different from a visit to the gynecologist or childbirth. It’s awkward and uncomfortable; no one likes to feel helpless and exposed in that manner. As if that were not enough, the femoral nerve running down the anterior compartment of the thigh (quadriceps femoris: rectus femoris, triplet vasti muscles) is also at risk of injury.
(3) I love yoga and pilates since beginning in college, and the exercises involve bending my limbs at funny angles and constantly working new muscles and particularly my breathing. Well, apparently the meditating lotus position can have negative reverberations from compressing the lateral side of the leg. Plus, I’ve finally understood why my legs went numb when I sat Indian style during elementary school story time. The numbness would first settle in, then the sudden pins & needles left me paralyzed for a good 5 minutes- painful and annoying. I’d have to sit like a block of wood until the sensation subsided. After all these years, now I know. I wonder how the Buddhist monks do it in the mountains…
(4) OooO now I also know why crossing my legs for barely 5 minutes causes tingling spasms, like when I sit Indian style. I’m a girl and I like to cross my legs in a lady-like fashion, but it comes with an annoying price: more pins and needles. Ouch. Well, the reason is because the common peroneal nerve travels rather superficially over the head of the fibula bone near the lateral side of the knee. When my leg crosses over, I am hitting the nerve; that’s why I need to constantly switch legs to relieve any pressure.
(5) This is a funny one, “Strawberry Picker’s Disease.” Conjure up in your head an old hunter and gatherer squatting down and moving swiftly like a monkey, picking up berries and bugs to eat. Well, not quite that barbaric, but you have an idea. The strawberry picker is crouching down and collecting fruits. It appears like an innocent, fresh outdoor activity, but the hamstrings tighten to keep the hip extended and the biceps femoris tendon compresses on the neck of the fibula where the peroneal nerve lies.