Everything about Sacral Plexus totally explained
In human
anatomy, the
sacral plexus is a
nerve plexus emerging from the
sacral vertebrae (S1-S4), and which provides nerves for the
pelvis and lower limbs.
Composition
The sacral plexus is formed by::
The nerves forming the sacral plexus converge toward the lower part of the
greater sciatic foramen, and unite to form a flattened band, from the anterior and posterior surfaces of which several branches arise.
The band itself is continued as the
sciatic nerve, which splits on the back of the thigh into the
tibial nerve and
common fibular nerve; these two nerves sometimes arise separately from the plexus, and in all cases their independence can be shown by dissection.
Often, the sacral plexus and the
lumbar plexus are considered to be one large nerve plexus, the
lumbosacral plexus. The
lumbosacral trunk connects the two plexuses.
Relations
The sacral plexus lies on the back of the pelvis between the
piriformis muscle and the
pelvic fascia. In front of it are the
internal iliac artery,
internal iliac vein, the
ureter, and the
sigmoid colon. The
superior gluteal artery and vein run between the
lumbosacral trunk and the first sacral nerve, and the
inferior gluteal artery and vein between the second and third sacral nerves.
Nerves formed
All the nerves entering the plexus, with the exception of the third sacral, split into ventral and dorsal divisions, and the nerves arising from these are as follows of the table below:
| Nerve |
Segments |
Muscles |
Cutaneous |
| Nerve to quadratus femoris |
L4-S1 |
gemellus inferior, quadratus femoris |
|
| Superior gluteal nerve |
L4-S1 |
gluteus medius, gluteus minimus, tensor fasciae latae |
|
| Sciatic nerve |
L4-S3 |
|
|
| * Tibial nerve |
L4-S3 |
posterior compartment |
posterolateral leg and foot - medial sural cutaneous nerve |
| * Common fibular nerve |
L4-S3 |
anterior compartment and lateral compartment |
anterolateral leg and foot - Lateral sural cutaneous nerve, medial dorsal cutaneous nerve, intermediate dorsal cutaneous nerve |
| Nerve to obturator internus |
L5-S2 |
gemellus superior, obturator internus |
|
| Inferior gluteal nerve |
L5-S2 |
gluteus maximus |
|
| Nerve to piriformis |
S1-S2 |
piriformis |
|
| Posterior cutaneous nerve of thigh |
S1-S3 |
- |
thigh |
| Perforating cutaneous nerve |
S2-S3 |
- |
- |
| Pudendal nerve |
S2-S4 |
bulbospongiosus, deep transverse perineal, ischiocavernosus, sphincter urethrae, superficial transverse perineal |
clitoris, penis |
| Coccygeal nerve |
S4-Co1 |
- |
perineum |
Additional images
Image:Gray838.png|The right sympathetic chain and its connections with the thoracic, abdominal, and pelvic plexuses.
Further Information
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