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Exploration of gluteal region and hip

Intrapelvic portions of obturator internus and piriformis muscles, medial view

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Image #181-3
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Exploration of gluteal region and hip
Intrapelvic portions of obturator internus and piriformis muscles, medial view
The pelvic contents have been removed and the sacral plexus on the right side has been cut away to expose the piriformis muscle. The nerves to the piriformis (19), derived from the first and second sacral nerves, have been preserved. The obturator internus (10) has also been dissected with its nerve supply. The insertions of both muscles are visible in the dissections illustrated in views 180-4 and 181-4.
1 . Lateral sacral artery (branch of Iliolumbar artery)
2 . Lumbar branch of iliolumbar artery
3 . Lumbosacral trunk
4 . Upper pointer: Superior gluteal artery Lower pointer: Body of ilium
5 . Iliolumbar artery (iliac branch)
6 . Obturator nerve
7 . Iliopsoas muscle
8 . Upper pointer: Obturator artery (entering obturator canal) Lower pointer: Pubic branch of obturator artery
9 . Body of pubis
10 . Obturator internus muscle
11 . Ischium
12 . Superior gluteal vein
13 . S1 nerve (emerging from posterior sacral foramen)
14 . Ramus communicans
15 . Sacral nerve II
16 . Sacral bone (body cut through to expose sacral canal)
17 . Sympathetic trunk
18 . Sacral bone
19 . Nerve to piriform muscle
20 . Piriform muscle
21 . Inferior gluteal artery
22 . Greater sciatic foramen (piriform muscle passing through)
23 . Coccygeus muscle
24 . Coccyx bone
25 . Ischial spine
26 . Nerve to Obturator internus muscle