Updated: 7/12/2019

Sciatic nerve

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Questions
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Evidence
2
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Videos / Pods
2
Topic

 

Innervation
  • Tibial division
    • motor
      •  semitendinous 
      •  semimembranous 
      •  long head biceps femoris 
      • topic gastrocnemius 
      • topic popliteus 
      •  plantaris 
      •  soleus 
      •  tibialis posterior 
      •  flexor digitorum longus 
      •  flexor hallucis longus 
    • sensory innervation
      • none
  • Peroneal division 
    • motor
      •  abductor hallucis 
      •  flexor digitorum brevis 
      •  flexor hallucis brevis 
      •  foot lumbricals 
      •  quadratus plantae 
      •  flexor digiti minimi 
      •  adductor hallucis 
      •  foot interossei
      •  abductor digiti minimi 
    • sensory 
      • articular branch to knee joint
      • sural nerve branch
        • runs distal with the small saphenous vein
        • anastomoses with a branch from the peroneal nerve
        • continues distal on lateral aspect of the Achilles tendon
        • terminates as the lateral dorsal cutaneous nerve of the foot
  • common peroneal nerve
    • motor
      •  short head of biceps femoris
    • deep peroneal nerve 
      • motor 
        • leg
          •  tibialis anterior  
          •  extensor digitorum longus  
          •  peroneus tertius  
          •  extensor hallucis longus   
        • foot
          • extensor digitorum brevis (lateral terminal branch)
          • extensor hallucis brevis  (lateral terminal branch)
      • sensory  
        • articular branch to the ankle joint    
        • medial terminal branch: 1st dorsal webspace
    • superficial peroneal nerve 
      • motor 
        • lateral compartment of leg
          •  peroneus longus 
          •  peroneus brevis   
      • sensory  
        • majority of skin on the dorsum of foot, excluding webspace between hallux and second digit (deep peroneal nerve)    
        • anterolateral distal 1/3 of leg
Origin
  • The sciatic nerve originates from lumbosacral plexus L4-S3 
    • tibial division
      • orginates from anterior preaxial branches of L4,L5,S1,S2,S3
    • peroneal division
      • originates from from postaxial branches of L4,L5,S1,S2
Course
  • Exits sciatic notch 
    • runs anterior or deep to piriformis
    • runs posterior or superficial to short external rotators (superior gemellus, inferior gemellus, obturator internus)  
  • Posterior leg
    • It then runs down the posterior leg where it breaks into its three main divisions at the level of the mid thigh
  • Terminal branches
    •  common peroneal nerve
    •  tibial nerve
Injury & Clinical Conditions
  • Iatrogenic Injury
    • methods to prevent injury
      • routine visual identification not advised in primary THA
      • palpation recommended
      • visual identification is recommended in revision THA
      • hip extension, knee flexion decreases tension on nerve

Please rate topic.

Average 3.8 of 21 Ratings

Questions (5)

(OBQ18.218) Which of the following statements regarding the peroneal division of the sciatic nerve is true?

QID: 213114
1

It crosses anterior to the lateral head of the gastrocnemius muscle through the posterior intermuscular septum

20%

(386/1914)

2

An injury at the level of the thigh will denervate the branches to the short head of the biceps and the tibialis anterior

47%

(895/1914)

3

It is most commonly injured during an anterior knee dislocation

12%

(230/1914)

4

The deep division initially runs medial to the tibial artery and later crosses over to become lateral

14%

(264/1914)

5

It originates from the L3-S1 nerve roots

6%

(124/1914)

L 5 A

Select Answer to see Preferred Response

(OBQ11.108) During total hip arthroplasty (THA) via a posterior approach, where is the sciatic nerve most likely to be found?

QID: 3531
1

Superficial to the piriformis and superficial to the short external rotators

4%

(194/4667)

2

Superficial to the piriformis and deep to the short external rotators

9%

(436/4667)

3

Deep to the piriformis and deep to the short external rotators

5%

(213/4667)

4

Deep to the piriformis and superficial to the short external rotators

80%

(3737/4667)

5

Splits the piriformis and is superficial to the short external rotators

1%

(60/4667)

L 2 C

Select Answer to see Preferred Response

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Evidence (2)
VIDEOS & PODCASTS (3)
EXPERT COMMENTS (11)
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