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Sacral plexus

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Sacral plexus

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
Latin plexus sacralis
From L4-L5, S1-S4
Dorlands
/Elsevier
p_24/12648416
Anatomical terms of neuroanatomy

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.

Contents

  • Structure 1
    • Relations 1.1
  • Nerves formed 2
  • Additional images 3
  • See also 4
  • Notes 5
  • References 6
  • External links 7

Structure

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:

Sacral plexus
Nerves of the sacral plexus[2]
Nerve Segment Innervated muscles Cutaneous 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
Coccygeal
(Coccygeal plexus)
S5-Co1 Coccygeus Anococcygeal
Dorsal branches

Additional images

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 the 20th edition of Gray's Anatomy (1918)


External links

  • 1490026564 at GPnotebook
  • Lumbosacral Plexus at the US National Library of Medicine Medical Subject Headings (MeSH)
  • Cross section image: pembody/body15a - Plastination Laboratory at the Medical University of Vienna
  • MedicalMnemonics.com: 3544 2382
  • Illustration at backpain-guide.com
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