Lumbosacral plexus

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The lumbosacral plexus (yellow) and its surrounding structures; the border cords and the nerve plexus around the abdominal aorta are also shown

The lumbosacral plexus or lumbar-cross plexus is a plexus of the ventral branches (ventrally directed nerve branches, rami ventrales ) of the spinal nerves of the lumbar and lower back (Th12 to max. S5, in humans there are five, in dogs only three vertebrae ) of the spinal cord . Through the exchange of nerve fibers from different spinal cord segments, new nerves emerge from this network , which now contain parts of several segments and innervate the lower extremity , the abdominal wall and the pelvis . While the lumbar nerves are only slightly woven, the cross-connections between the cross nerves are very pronounced.

Nerves of the lumbosacral plexus

The splitting of the nerves is remarkably uniform in the mammals , so that a common representation of humans and animals can take place. The lumbosacral plexus is occasionally further subdivided into a lumbar , sacral , pudendal, and coccygeus plexus , although this division is anatomically not very useful.

Lumbar section of the lumbosacral plexus

Lumbar plexus

Origin in humans from Th12 – L4, via rami communicantes in connection with the lumbar part of the sympathetic trunk , short muscles to supply the psoas major , psoas minor and quadratus lumborum muscles . The lumbar plexus also supplies the extensors and adductors of the thigh as well as the sensitive front of the thigh and the front and inside of the lower leg. In the lumbar plexus, a distinction is made between the following nerves:

  1. Iliohypogastric nerve (Th12-L1)
  2. Ilioinguinal nerve (Th12-L1)
  3. Genitofemoral nerve (L1-L2)
  4. Lateral femoral cutaneous nerve (L2 – L3)
  5. Femoral nerve (L1 – L4)
  6. Obturator nerve (L2-L4)

Sacral plexus

The sacral plexus consists of the anterior (ventral) rami of the 1st to 3rd sacral nerves and the lumbosacral trunk of the anterior branches of the 4th and 5th lumbar nerves. Damage to the sacral plexus causes sensory disturbances on the back of the thigh, the entire lower leg and the foot. Motor paralysis is found in the hip extensors, knee flexors and all lower leg and foot muscles. All nerves of the plexus leave the pelvis through the infrapiriforme foramen (caudal portion of the greater sciatic foramen below the piriformis muscle). The exception is the superior gluteus nerve, which leaves the pelvis through the suprapiriform foramen . A distinction is made between the following nerves:

  1. Nervus gluteus superior (L4 – S1, in animals called N. gluteus cranialis )
  2. Nervus gluteus inferior (L5 – S2, animals: N. gluteus caudalis )
  3. Nervus cutaneus femoris posterior (S1 – S3, animals: N. cutaneus femoris caudalis )
  4. Sciatic nerve (sciatic nerve, L4 – S3)
    branches into the tibial nerve and the common peroneal nerve (fibularis)
  5. Pudendal nerve (S1 – S4)
  6. Nervi anococcygei (in animals: N. rectalis caudalis or N. rectales caudales )

See also

Individual evidence

  1. ↑ Federative Committee on Anatomical Terminology (1998). Terminologia Anatomica . Stuttgart: Thieme
  2. ^ A b c Franz-Viktor Salomon: Nervous system, Systema nervosum . In: Franz-Viktor Salomon (Ed.): Anatomy for veterinary medicine . 3. Edition. Enke, Stuttgart 2015, ISBN 978-3-8304-1288-5 , pp. 564-571 .
  3. ↑ a b Walther Graumann, Dieter Sasse: Compact textbook anatomy . tape 4 . Schattauer, Stuttgart 2005, ISBN 978-3-7945-2064-0 , pp. 432-438 .