Innervation and function of rat tail muscles for modeling cauda equina injury and repair

Muscle Nerve. 2015 Jul;52(1):94-102. doi: 10.1002/mus.24498. Epub 2015 May 29.

Abstract

Introduction: The rat tail exhibits functional impairment after cauda equina injury. Our goal was to better understand the innervation and roles of muscles that control the tail.

Methods: Adult rats received either: (1) ventral root injury; (2) caudales nerve injury; or (3) mapping of sacrococcygeal myotomes. Activation of small muscles within the tail itself (intrinsics) was compared with that of larger lumbosacral muscles acting on the tail (extrinsics). Behavioral testing of tail movement was done 1 week later.

Results: Rats that received ventral root injury exhibited multiple behavioral deficits, whereas rats with injury to caudales nerves maintained more fully preserved tail movement. Mapping studies revealed much broader overlap of myotomes for extrinsic muscles.

Conclusions: Extrinsic tail muscles play a greater role in tail movement in the rat than their intrinsic counterparts and are innervated by multiple neurological segments. These findings have major implications for future research on cauda equina injury.

Keywords: cauda equina; evoked EMG; mapping; nerve root; ventral.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Animals
  • Disease Models, Animal
  • Electromyography
  • Female
  • Gait Disorders, Neurologic / etiology
  • Movement / physiology
  • Muscle, Skeletal / physiopathology*
  • Polyradiculopathy / complications
  • Polyradiculopathy / pathology*
  • Rats
  • Rats, Sprague-Dawley
  • Spinal Nerve Roots / physiopathology
  • Swimming / physiology
  • Tail / innervation*
  • Tail / physiopathology
  • Wound Healing / physiology*