Re: Gluteal Region and the Ischio Rectal Fossa - Study Guide Part II

Comments:
: : : 1. The gluteus medius lies deep to the the gluteus maximus and superficial to the gluteus minimus. : : TRUE. : : This is rather apparent when one looks at a properly dissected cadaver. : Agreed. Should be apparent with a less than proper dissection. : : : 2. The gluteus medius lies anterior to the gluteus maximus and posterior to the gluteus minimus. : : TRUE. : : This is also rather apparent when one looks at a properly dissected cadaver. : Agreed. Anatomical position. : : : 3. The inferior gemellus originates from the ischial tuberosity and blends with the tendon of the obturator externus. : : FALSE. : : Inferior gemellus originates from the ischial tuberosity and blends with the tendon of the obturator internus, not externus. : Agreed. : : : 4. The superior gemellus arises from the ischial spine and blends with the tendon of the obturator internus. : : TRUE. : : If one looks at a dissection of the obturator internus, it is observable that the superior gemellus lies superiorly to the tendon of the obturator internus, originates on the ischial spine, and inserts into the the tendon of the obturator internus. : Agreed. Great. to insert on the greater trochanter via internus. : : : 5. The superior gluteal nerve travels transversely deep to the gluteus medius and superficial to gluteus minimus toward the tensor fascia lata. : : TRUE. : : The superior gluteal nerve innervates the gluteus medius, gluteus minimus, and the tensor fascia lata. : Agreed. Nifty. The anatomical relationships reveal the efficiency of the innervation. : : : 6. Piriformis, superior gemellus, obturator internus, inferior gemullus, and quadratus femoris make up 5 short lateral rotators of the hip. : : TRUE. : : Obturator externus is also a lateral rotator of the hip (so there are 6 of them) : Agreed. : : : 7. The origins of the superior and inferior gemeli are interrupted by the greater sciatic notch. : : FALSE. : : It is interrupted by the lesser sciatic notch. : Agreed. : : : 8. The superior gluteal nerve and the sciatic nerve enter the gluteal region by passing superior to the piriformis. : : FALSE. : : Superior gluteal nerve enters the gluteal region by passing superior to piriformis whereas the sciatic nerve typically enters the gluteal region inferior to piriformis (the exception would be the 12% of specimens in which the sciatic nerve enters the gluteal region superior to piriformis or pierces piriformis) : Agreed. excellent : : : : : 9. The lumbar plexus receives ventral rami, but not dorsal rami, from spinal nerves. : : TRUE. : : We're not as sure with this one... But we believe that this is an intrinsic property of the lumbar plexus. : Agreed. This is tough. I am a little mixed, like a nerve, on this. : : : 10. The lumbar plexus, a somatic plexus, elaborates the femoral and obturator nerves (non-exhaustive). : : TRUE. : : Obturator is elaborated by L2 to L4 and femoral is elaborated by L2 to L4 : Agreed. Specific levels will vary by source. : : : 11. The sacral plexus, a somatic plexus, elaborates the sciatic nerve, superior gluteal nerve, and inferior gluteal nerve (non-exhaustive). : : TRUE. : : Sciatic: L4, L5, S1 to S3 : : Superior gluteal nerve: L4 to S1 : : Inferior gluteal nerve: L5 to S2 : Agreed. excellent. : : : 12. A peripheral nerve derived from a plexus typically contributes to more than one dermatome. : : TRUE: : : A peripheral nerve can innervate an area that encompasses more than one dermatome. : Agreed. This is an important but difficult concept. We have awhile for it to sink in; with some luck. : : : 13. A spinal nerve contributes to one dermatome only. : : TRUE. : : This is essentially the meaning of the word “dermatome.” : Agreed. : : : 14. A dermatomal region of anesthesia indicates spinal nerve damage (eg. herniated disc). : : TRUE. : : Since the whole dermatome is numb that does indicate that the spinal nerve is damaged. If only a root was damaged then only a portion of the dermatome that is innervated by that particular root would exhibit that numbness. We think.... : Agreed. But not quite right on your interpretation. This is tough and nervy. : : : 15. A cross-dermatomal region of anesthesia indicates damage to a peripheral nerve (eg. nerve entrapment). : : TRUE. : : If more than one dermatome is asensate, this would either imply damage to multiple spinal nerves or a peripheral nerve innervating a more varied cutaneous region. : Agreed. Cross dermatomal = peripheral nerve entrapment. Dermatomal = spinal nerve compression. As you point out, multiple spinal nerve compression could masquerade as peripheral nerve entrapment but there would likely be inconsistencies. : : We decided not to write out answers to the essay-type questions. : : Again, Dr. Evey, if you could comment on and/or correct our answers, we would be very appreciative! : : Thanks! : Your Welcome!

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