Langenbach G E, Weijs W A
Department of Anatomy and Embryology, Academic Center for Dentistry Amsterdam ACTA, The Netherlands.
J Dent Res. 1990 Jan;69(1):20-5. doi: 10.1177/00220345900690010201.
The post-natal growth of the masticatory muscles in the rabbit was examined. By means of anatomical dissection and measurement, total muscle length, muscle fiber length, and muscle weight were determined in animals varying in age between one week and 36 months and exhibiting a 50-fold weight increase. Growth data were fitted by linear regression models with facial skull length used as the independent variable. Many deviations occur from size-dependent isometric growth. The muscles can be divided into three groups, according to their pattern of weight increase: The jaw openers grow negatively allometrically, and their contribution to total muscle weight decreases with time; the temporal muscle grows negatively allometrically, but its relative weight proportion remains about the same; the masseter and medial pterygoid muscles have positively allometric growth, and their contribution to total muscle weight increases strongly. Generally, the length of the muscles and of their fibers increases at lower rates than does the length of the facial skull. After weaning, the rate of longitudinal growth drops steeply in some muscles. Total fiber area or physiological cross-section (PCS) of muscles is computed from weight and fiber length. It increases positively allometrically in the jaw closers and negatively allometrically in the jaw openers. In the lateral pterygoid muscle, the increase of PCS changes from negatively- to positively-allometric growth after weaning. The study demonstrates that individual oral muscles follow different patterns of longitudinal and cross-sectional growth, so that their functional capacities (force, range of contraction) and mutual functional relationships are age-dependent.
对家兔咀嚼肌的出生后生长情况进行了研究。通过解剖和测量，测定了年龄在1周龄至36月龄之间、体重增长达50倍的动物的肌肉总长度、肌纤维长度和肌肉重量。以面颅骨长度作为自变量，用线性回归模型拟合生长数据。出现了许多与大小相关的等长生长偏差。根据肌肉重量增加模式，这些肌肉可分为三组：张口肌呈负异速生长，其在肌肉总重量中的占比随时间下降；颞肌呈负异速生长，但其相对重量比例保持大致相同；咬肌和翼内肌呈正异速生长，它们在肌肉总重量中的占比大幅增加。一般来说，肌肉及其纤维的长度增长速度低于面颅骨的长度增长速度。断奶后，某些肌肉的纵向生长速度急剧下降。根据肌肉重量和纤维长度计算肌肉的总纤维面积或生理横截面积（PCS）。在闭口肌中，PCS呈正异速增长，在张口肌中呈负异速增长。在翼外肌中，断奶后PCS的增长从负异速生长转变为正异速生长。该研究表明，个体口腔肌肉遵循不同的纵向和横截面积生长模式，因此它们的功能能力（力量、收缩范围）和相互功能关系取决于年龄。
