| Objective:To provide a detailed morphologic data for further studying the physiological function and clinical application of erector spinae by researching into those muscles'architecture and muscle spindles.Methods:1.To obtain bilateral erector spinae completely from 6 adult cadavers which have been fixed by formalin. First to observe the shape, enthesis and arrangement form of muscle bundles of erector spinae. And then to study the muscle architecture of the muscles.2. In order to observe the muscle architecture feature of erector spinae, muscle architecture indices of erector spinae were measured according to muscle architecture method in 6 adult cadavers, which were muscle weight(MW), muscle length(ML), fiber length(FL)and physiologic cross sectional area(CSA), etc.3. The muscle spindle specimens of erector spinae were raked out in 5 adult cadavers. HE staining technique and stereology method were used to study their muscle spindle distribution.Results:1. Gross-anatomy:1. Gross-anatomy:Since first vertebra spine was above plane, spinalis, longissimus and iliocostalis could be completely separated by two longitudinal and shallow grooves. Unipennate muscle consists of spinalis which was constituted by many smallish and thick muscle tendon and many short fibres that was close to spine and was attached to the surface of bone. Multipennate muscle up to the breast was formed by many wide and flat muscle tendon boards next to longissimus, close to sacral portion, and a large number of muscle fibres which were attached to the muscle tendon board. Unipennate muscle up to the neck was constituted by muscle tendon board and muscle fibres of longissimus from the breast which was attached to tendon board. Unipannate muscle was formed by fibres in liocostails from muscle belly to up which increasingly become thin from thick, whose number was increasingly reducing, and superficial muscle aponeurosis that was formed by wide and flat long muscle tendon from the surface of bone and whose long fibres gradation stops in the back of tendon board from back to belly.2. Muscle Building Characteristics:①muscle weight:total weight of the vertical muscles: (371.41±44.10) g; Spinalis:(61.16±13.26) g; Longissimus:(197.88±16.53) g; Iliocostalis (113.29±17.51) g.②muscle length:Spinalis:(52.86±2.35) cm; Longissimus: (57.51±2.78) cm; Iliocostalis (52.55±3.32) cm.③muscle fiber length:Spinalis:(5.75±0.78) cm; Longissimus:(11.85±1.58) cm; Iliocostalis (11.78±1.30) cm.±feather angle: Iliocostalis, Longissimus, Spinalis are 10°.⑤physiological cross sectional area:Spinalis: (8.68±2.60) cm2; Longissimus:(13.41±1.59) cm2; Iliocostalis (7.73±1.48) cm2.3. Distribution of muscle spindles:Muscle spindle density is (5.43±3.46)个/cm3; muscle spindle index:(5.14±2.27)个/g; maximum muscle spindle density: (13.22±2.32)个/cm3, muscle spindle index:(12.51±2.16)个/g; iliac rib muscle spindle density (12.07±2.51)个/cm3, muscle spindle index (11.42±1.17)个/g.Conclusion:1. Among three parts of erector spinae, spinalis is bipennate muscles formed by short muscle bundle and the portion below one-third of iliocostalis and longissimus is multipennate muscle formed by short muscle bundle and the portion above two-third is unipannate muscle formed by long muscle bundle. Erector spinae consists of bipennate and unibipennate muscle.2. CSA/MW of spinalis has maximum ration among three parts and tends to be strength-type structure. Longissimus and iliocostalis have the features of architectonics which are strength and speed type. And they provide the myosthenic potential, as well as serve for speed movement.3. The high density of muscle spindle in erector spinae plays an important role in sustaining the stability of spine. |
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