Anatomy and Embryology

, Volume 207, Issue 3, pp 193–208

Blink-related sensorimotor anatomy in the rat

Original Article

DOI: 10.1007/s00429-003-0341-6

Cite this article as:
Gong, S., Zhou, Q. & LeDoux, M.S. Anat Embryol (2003) 207: 193. doi:10.1007/s00429-003-0341-6

Abstract

Protection of the eye and maintenance of the precorneal tear film depend on sensory innervation of the cornea and eyelids and motor innervation of muscles involved in closing and opening the eyes. Using a variety of fluorescent and transganglionic tracers, the sensorimotor innervation of blink-related orbital and periorbital structures was studied in Sprague-Dawley rats. The orbicularis oculi muscle surrounded the entire palpebral fissure and was innervated by motoneurons located along the dorsal cap of the ipsilateral facial motor nucleus. Upper and lower eyelid orbicularis oculi motoneurons were strictly ipsilateral and co-extensive, but upper eyelid orbicularis oculi motoneurons were, on average, slightly rostral and lateral to lower eyelid orbicularis oculi motoneurons. Facial motoneurons supplying the frontoscutularis, a muscle that helps to elevate the upper eyelid, were located in the medial division of the ipsilateral facial motor nucleus. Presumptive type Aβ afferents from the cornea terminated most prominently at the junction of the first cervical segment and the spinal trigeminal nucleus, pars caudalis. There was a second concentration of corneal terminations at the junction of pars caudalis and pars interpolaris of the spinal trigeminal nucleus. Sparse projections to the spinal trigeminal nucleus, pars oralis and the principal trigeminal nucleus were also detected. Presumptive type Aβ afferents from the eyelids terminated throughout the rostrocaudal extent of the spinal trigeminal nucleus with a heavy concentration within laminae III and IV of the first cervical segment. Presumptive types Aδ and C terminals from the eyelids were virtually limited to laminae I and II of the first cervical segment. Central terminations from the frontal nerve were present in the principal trigeminal nucleus and throughout the spinal trigeminal nucleus, but were most prominent within the dorsal horn of the first cervical segment. Our comprehensive description of blink-related sensorimotor anatomy in rats will provide a foundation for future physiological studies of blinking.

Keywords

Trigeminal Orbicularis oculi Motoneurons Cholera toxin Eyelid 

Abbreviations

I, II, III, IV and V

spinal cord laminae

7

facial nucleus

C1, C2 and C3

first, second and third cervical segments

CTB

B subunit of cholera toxin

DAB

diaminobenzidine

DMSO

dimethylsulfoxide

DY

Diaminido Yellow

FB

Fast Flue

FG

Fluorogold

IR

immunoreactivity

LP

levator palpebrae

Mo5

motor trigeminal nucleus

OO

orbicularis oculi

PB

phosphate buffer

PBS

phosphate buffered saline

PCRt

parvicellular reticular nucleus

Pr5

principal trigeminal nucleus

R1, R2

first and second components of the blink reflex to supraorbital nerve stimulation

sp5

spinal trigeminal tract

Sp5

spinal trigeminal nucleus

Sp5C, Sp5I, Sp5O

pars caudalis, pars interpolaris, and pars oralis of spinal trigeminal nucleus

WGA-HRP

wheat germ agglutinin-horseradish peroxidase

Copyright information

© Springer-Verlag 2003

Authors and Affiliations

  1. 1.Department of NeurologyUniversity of Tennessee Health Science CenterMemphisUSA
  2. 2.Department of Anatomy and NeurobiologyUniversity of Tennessee Health Science CenterMemphisUSA

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