Sacral plexus

In human anatomy, the sacral plexus is a nerve plexus which provides motor and sensory nerves for the posterior thigh, most of the lower leg and foot, and part of the pelvis. It is part of the lumbosacral plexus and emerges from the lumbar vertebrae and sacral vertebrae (L4-S4).[1] A sacral plexopathy is a disorder affecting the nerves of the sacral plexus, usually caused by trauma, nerve compression, vascular disease, or infection. Symptoms may include pain, loss of motor control, and sensory deficits.

Sacral plexus
Plan of sacral and pudendal plexuses.
Relations of the sacral plexus. Dissection of side wall of pelvis showing sacral and pudendal plexuses.
Details
FromL4-L5, S1-S4
Identifiers
Latinplexus sacralis
TAA14.2.07.027
FMA5909
Anatomical terms of neuroanatomy

Structure

The sacral plexus is formed by:

  • the lumbosacral trunk
  • the anterior division of the first sacral nerve
  • portions of the anterior divisions of the second and third sacral nerves

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 in front of 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:

Sacral plexus
Nerves of the sacral plexus[2]
NerveSegmentInnervated musclesCutaneous branches
Superior gluteal L4-S1 Gluteus medius
Gluteus minimus
Tensor fasciae latae		  
Inferior gluteal L5-S2 Gluteus maximus  
Posterior cutaneous femoral S1-S3  

Posterior cutaneous femoral

• Inferior cluneal nerves
• Perineal branches
Direct branches from plexus
• Piriformis
 S1-2 Piriformis  
• Obturator internus
 L5, S1-2 Obturator internus and Superior gemellus  
• Quadratus femoris
 L4-5, S1 Quadratus femoris and Inferior gemellus  
Sciatic
Sciatic L4-S3 Semitendinosus (Tib)
Semimembranosus (Tib)
Biceps femoris
• Long head (Tib)
• Short head (Fib)

Adductor magnus (medial part, Tib)

  
Common fibular L4-S2   Lateral sural cutaneous
Communicating fibular
• Superficial fibular
   Peroneus longus
Peroneus brevis		 Medial dorsal cutaneous
Intermediate dorsal cutaneous
• Deep fibular
   Tibialis anterior
Extensor digitorum longus
Extensor digitorum brevis
Extensor hallucis longus
Extensor hallucis brevis
Peroneus tertius		 Lateral cutaneous nerve of big toe
Intermediate dorsal cutaneous
Tibial nerve L4-S3 Triceps surae
Plantaris
Popliteus
Tibialis posterior
Flexor digitorum longus
Flexor hallucis longus		 Medial sural cutaneous
Lateral calcaneal
Medial calcaneal
Lateral dorsal cutaneous
• Medial plantar
   Abductor hallucis
Flexor digitorum brevis
Flexor hallucis brevis (medial head)
Lumbrical (first and second)		 Proper digital plantar
• Lateral plantar
   Flexor hallucis brevis (lateral head)
Quadratus plantae
Abductor digiti minimi
Flexor digiti minimi
Lumbrical (third and fourth)
Plantar interossei (first to third)
Dorsal interossei (first to fifth)
Adductor hallucis		 Proper plantar digital
Pudendal and coccygeal
Pudendal
(Pudendal plexus)		 S2-S4 Muscles of the pelvic floor:
Levator ani
Superficial transverse perineal
Deep transverse perineal
Bulbospongiosus
Ischiocavernosus
Sphincter anus externus
Urethral sphincter		 Inferior rectal
Perineal
• Posterior scrotal/labial
• Dorsal penis/clitoris
• prostatic urethra./vagina
Coccygeal
(Coccygeal plexus)		 S5-Co1 Coccygeus Anococcygeal
Dorsal branches

Additional images
  • The right sympathetic chain and its connections with the thoracic, abdominal, and pelvic plexuses.
  • A schematic depiction.
  • diagram of the Sacral plexus
gollark: <@249224113095180289> You can get maps apps which download from openstreetmap ot something.
gollark: Fun fact: if you just train a *person* to do a task, you're technically "training a neural network" to do it!
gollark: There's an entire subreddit of people with... well, that sort of thing.
gollark: A crossbow which shoots arrows containing small batteries and lasers, that is.
gollark: Make a laser crossbow. Obviously.

See also

Notes
  1. Thieme Atlas of Anatomy (2006), pp 470-471
  2. Thieme Atlas of Anatomy (2006), pp 476, 478, 482

References

This article incorporates text in the public domain from page 957 of the 20th edition of Gray's Anatomy (1918)

  • Thieme Atlas of Anatomy: General Anatomy and Musculoskeletal System. Thieme. 2006. ISBN 1-58890-419-9.
This article is issued from Wikipedia. The text is licensed under Creative Commons - Attribution - Sharealike. Additional terms may apply for the media files.