TBL8 - Sacrum and Gluteal Region Flashcards
How many vertebrae is the sacrum composed of? What does the vertebral canal become as it enters the sacrum?
1) The sacrum is composed of five fused sacral vertebrae
2) The vertebral canal continues into the sacrum as the sacral canal
What is the sacral hiatus?
1) The inverted U-shaped sacral hiatus opens into the sacral canal
2) The hiatus results from absence of the laminae and spinous process of S5
What are the sacral cornua?
The sacral cornua project inferiorly on both sides of the hiatus thus providing a guide to its location
Where do the sacral nerve roots of the cauda equina reside? What is the function of the anterior and posterior sacral foramina?
1) The sacral nerve roots of the cauda equina reside in the sacral canal
2) The anterior and posterior sacral foramina provide exits for the anterior and posterior rami of spinal nerves S1-S4 (S5 rami exit between vertebra S5 and the coccyx)
How is caudal epidural anesthesia performed and which spinal nerves are typically affected?
1) In caudal epidural anesthesia or caudal analgesia, a local anesthetic agent is injected into the fat of the sacral canal that surrounds the proximal portions of the sacral nerves. This can be accomplished by several routes, including the sacral hiatus
2) The anesthetic solution spreads superiorly and extradurally, where it acts on the S2–Co1 spinal nerves of the cauda equina
What is the function of the posterior and anterior sacroiliac ligaments? What is the function of the sacrotuberous and sacrospinous ligaments? What is the function of the greater sciatic foramen?
1) The posterior and anterior sacroiliac ligaments hold the hip bones and sacrum together
2) The sacrotuberous and sacrospinous ligaments connect the sacrum to the ischial tuberosity and ischial spine, respectively and thereby create the greater and lesser sciatic foramina
3) The greater sciatic foramen is a conduit for structures passing between the pelvis and gluteal region
What is the location of the gluteal region? What occupies most of this region?
1) The gluteal region encompasses the area inferior to the iliac crests and laterally to the greater trochanters of the femurs
2) Gluteal muscles occupy and form the bulk of the region
Where does the gluteus maximus attach to proximally? Where does the gluteus maximus attach to distally? What is its innervation? What is its function?
1) The gluteus maximus, the largest and most superficial gluteal muscle, attaches proximally to the superoposterior ilium and posterior sacrum
2) It attaches distally to the iliotibial tract
3) It is innervated by the inferior gluteal nerve (L5, S1, S2)
4) The gluteus maximus is the strongest extensor of the thigh particularly from the flexed position as when rising from a sitting position or walking up stair
Where is the gluteus medius located in relation to the gluteus maximus? Where does the gluteus medius attach to proximally? What does the gluteus medius muscle cover? What is the common innervation between the gluteus medius and minimus? What is their common distal attachment?
1) The gluteus maximus covers most of the smaller gluteus medius
2) The gluteus medius attaches proximally to the external surface of the ilium
3) The gluteus medius covers the entire gluteus minimus muscle
4) The common innervation of the gluteus medius and minimus is the superior gluteal nerve (L5, S1)
5) The common distal attachment of the gluteus medius and minimus is the greater trochanter of the femur. The gluteus medius attaches to the lateral surface of the greater trochanter, while the gluteus minimus attaches to the anterior surface of the greater trochanter
What is the function of the gluteus medius and minimus?
The gluteus medius and minimus abduct and medially rotate the thigh
What are the main lesions that cause a positive Trendelenburg test?
1) When a person who has suffered a lesion of the superior gluteal nerve is asked to stand on one leg, the pelvis on the unsupported side descends, indicating that the gluteus medius and minimus on the supported side are weak or non-functional. This sign is referred to clinically as a positive Trendelenburg test
2) Other causes of this sign include fracture of the greater trochanter (the distal attachment of gluteus medius) and dislocation of the hip join
Where is the safe area for intragluteal injections?
Injections into the buttocks are safe only in the superolateral quadrant of the buttocks or superior to a line extending from the PSIS to the superior border of the greater trochanter (approximating the superior border of the gluteus maximus)
Where does the tensor fasciae lata muscle attach to proximally and distally? What is its innervation? What is its function?
1) The tensor fasciae lata muscle attaches proximally to the ASIS and distally to the iliotibial tract (just like the gluteus maximus), which attaches to the superolateral tibia
2) It is innevated by the superior gluteal
nerve (L5, S1)
3) It synergizes with other stronger muscles during flexion of the thigh
Paralysis of which muscle activates hypertrophy of the tensor fascia lata?
When the iliopsoas is paralyzed, the tensor fasciae latae undergoes hypertrophy in an attempt to compensate for the paralysis
What does the piriformis muscle attach to distally and proximally? Where does the piriformis muscle course to? What space does it occupy significantly?
1) The piriformis muscle attaches distally to the greater trochanter of the femur
2) In the pelvis, it attaches proximally to the anterior surface of the sacrum
3) It courses from the pelvis to the greater trochanter
4) During this course, it occupies most of the greater sciatic foramen
