TY - JOUR
T1 - Compartmentalized innervation of primate lateral rectus muscle
AU - Peng, Michelle
AU - Poukens, Vadims
AU - Costa, Roberta Martins da Silva
AU - Yoo, Lawrence
AU - Tychsen, Lawrence
AU - Demer, Joseph L.
PY - 2010/9
Y1 - 2010/9
N2 - PURPOSE. Skeletal and craniofacial muscles are frequently composed of multiple neuromuscular compartments that serve different physiological functions. Evidence of possible regional selectivity in LR intramuscular innervation was sought in a study of the anatomic potential of lateral rectus (LR) muscle compartmentalization. METHODS. Whole orbits of two humans and five macaque monkeys were serially sectioned at 10-m thickness and stained with Masson trichrome. The abducens nerve CN6) was traced anteriorly from the deep orbit as it branched to enter the LR and arborized among extraocular muscle (EOM) fibers. Threedimensional reconstruction was performed in human and monkey orbits. RESULTS. Findings were in concordance in the monkey and human orbits. External to the LR global surface, CN6 bifurcated into approximately equal-sized trunks before entering the global layer. Subsequent arborization showed a systematic topography, entering a well-defined inferior zone 0.4 to 2.5 mm more posteriorly than branches entering the largely nonoverlapping superior zone. Zonal innervation remained segregated anteriorly and laterally within the LR. CONCLUSIONS. Consistent segregation of intramuscular CN6 arborization in humans and monkeys suggests functionally distinct superior and inferior zones for the LR. Since the LR is shaped as a broad vertical strap, segregated control of the two zones could activate them separately, potentially mediating previously unappreciated but substantial torsional and vertical oculorotary LR actions.
AB - PURPOSE. Skeletal and craniofacial muscles are frequently composed of multiple neuromuscular compartments that serve different physiological functions. Evidence of possible regional selectivity in LR intramuscular innervation was sought in a study of the anatomic potential of lateral rectus (LR) muscle compartmentalization. METHODS. Whole orbits of two humans and five macaque monkeys were serially sectioned at 10-m thickness and stained with Masson trichrome. The abducens nerve CN6) was traced anteriorly from the deep orbit as it branched to enter the LR and arborized among extraocular muscle (EOM) fibers. Threedimensional reconstruction was performed in human and monkey orbits. RESULTS. Findings were in concordance in the monkey and human orbits. External to the LR global surface, CN6 bifurcated into approximately equal-sized trunks before entering the global layer. Subsequent arborization showed a systematic topography, entering a well-defined inferior zone 0.4 to 2.5 mm more posteriorly than branches entering the largely nonoverlapping superior zone. Zonal innervation remained segregated anteriorly and laterally within the LR. CONCLUSIONS. Consistent segregation of intramuscular CN6 arborization in humans and monkeys suggests functionally distinct superior and inferior zones for the LR. Since the LR is shaped as a broad vertical strap, segregated control of the two zones could activate them separately, potentially mediating previously unappreciated but substantial torsional and vertical oculorotary LR actions.
UR - http://www.scopus.com/inward/record.url?scp=77957345735&partnerID=8YFLogxK
U2 - 10.1167/iovs.10-5330
DO - 10.1167/iovs.10-5330
M3 - Article
C2 - 20435590
AN - SCOPUS:77957345735
SN - 0146-0404
VL - 51
SP - 4612
EP - 4617
JO - Investigative Ophthalmology and Visual Science
JF - Investigative Ophthalmology and Visual Science
IS - 9
ER -