Lab 5 - Module 3 - Hip and Anterior Thigh - Lumbosacral Plexus and Nerves of the Thigh: Page 2 of 2
Sacral Plexus
The Sacral Plexus joins the lumbar plexus giving contributions from L4 and L5 via the lumbosacral trunk.
Tap on image to enlarge
Add the L5 nerve root.
Add the S1 nerve root.
Add the S2 nerve root.
Add the S3 nerve root.
Add the Sciatic Nerve which is the largest branch of the sacral plexus. The sciatic nerve exits the pelvis via the Greater Sciatic Foramen. The Greater Sciatic Foramen is defined by the opening created by the ilium, sacrum, the sacrotuberous and sacrospinous ligaments. The sacrospinous ligament is (NOT IDENTIFIED IN THIS CADAVER).
Add the Sacrotuberous Ligament.
Rotate the cadaver for a posterior view.
Add the Piriformis muscle. The sciatic nerve is actually two separate nerves that are wrapped in a common sheath until it passes the piriformis muscle. Once it passes the piriformis muscle the two nerves leave the common sheath to take their own separate paths to the lower leg. The two nerves that run in this common sheath are the:
Common Fibular (Peroneal) Nerve
Tibial Nerve.
The Common Fibular (Peroneal) Nerve is formed by the posterior divisions of L4-S2 (NOT IDENTIFIED IN THIS CADAVER).
Add the Superior Gluteal Nerve (L4-S1).
Add the Inferior Gluteal Nerve (L5-S2).
Add the Posterior Femoral Cutaneous (S1-S2).
The Tibial Nerve (L4-S3) is a continuation of the Sciatic Nerve. Two small nerves also come from the anterior divisions, nerve to the quadratus femoris and inferior gemellus (L4-S1). There is also the nerve to the obturator internus and superior gemellus from L5-S2.
