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Wheeless' Textbook of Orthopaedics

Gastrocnemius   


- See:
      - Achilles Tendon:
      - Gastrocnemius Flap: (see reconstructive surgery for the leg):


- Anatomy: (see superficial posterior compartment);
    - origin:
         - lateral head: lateral condyle and posterior surface of femur;
         - medial head: medial condyle and adjacent part of femur;
    - insertion: posterior surface of calcaneus by means of calcaneal tendon;
    - action:
         - plantar flexion of the foot;
         - rervesed origin insertion of action: flexes leg at the knee;
         - doriflexion of the foot increases knee flexion capability;
     - synergists: soleus, tibialis posterior, peroneus longus and brevis,  flexor hallucis longus, flexor digitorum longus;
     - nerve supply: tibial, S1  >  L5, (see innervation)


- Function During Gait: (gait)
    - triceps surae help to support knee during stance phase;
    - helps decelerate tibial advancement during stance phase;
    - exam: normally patients should be able to perform more than 20 heel raises;


- Parlysis of the Triceps Surae Muscle:
    - paralysis of the triceps leads to a calcaneal deformity of the foot;
           - deformity occurs as a result of unopposed dorsiflexor function combined with attenuation of of the triceps surae;
    - when the triceps surae is weak, the tibialis posterior, peronei, and long toe flexors are ineffective hind foot plantarflexors;
    - the ability to decelerate the tibia is lost and therefore, flexion of the knee will persist throughout stance phase;
           - in order to prevent this, the patient may attempt to compensate with increased quadriceps activity during a larger portion of stance phase;
    - there is an increase in ankle dorsiflexion as talus is displaced upward & as os calcis rotates under and into a more verticle position;
           - patient will be noted to maintain heel contact during the terminal stance phase;
     - forefoot develops equinus position, therby creating cavus deformity;
     - effect on contra-lateral (uninvolved limb):
           - unilateral paralysis of the triceps surae will shorten the stride length of the contralateral limb;
     - management:
           - a dorsiflexion stop should be provided to patients w/ normal dorsiflexion;
           - equinus contracture can compensate for weak triceps surae, since contracture will resist tendency for excessive dorsiflexion during terminal stance phase;
                 - in addition an equinus contracture would lessen the work load of the quads, in trying to prevent knee flexion during stance phase;
                 - in contrast, heel cord lengthening would be expected to dramatically worsen the function of a patient w/ a weakened triceps



Knee dysfunction secondary to dislocation of the fabella.

Function of the triceps surae during gait. Compensatory mechanisms for unilateral loss.

Anatomical aspects of the blood supply to the skin of the posterior calf: technique of below-knee amputation.

Isolated Recession of the Gastrocnemius Muscle: The Baumann Procedure



Original Text by Clifford R. Wheeless, III, MD.

Last updated by Data Trace Staff on Tuesday, April 10, 2012 4:42 pm