[Distribution of the muscle spindles in human masticatory muscles].
OBJECTIVE
To investigate the characteristics in the topographic distribution of the muscle spindles in human masticatory muscles.


METHODS
The muscle spindles of the masticatory muscles on both sides of 3 human corpses fixed in formalin for more than 1 year were observed histologically and analyzed quantitatively using an image analysis system.


RESULTS
The mean muscle spindle density was 32.11/g in the masseter, significantly higher in the deep muscular fibers (70.76/g) with high proportion of spindle complexes than in the superficial layers of the muscle belly (P<0.05). The mean spindle density in the temporalis was 5.44/g, higher in the anterior portion (7.44/g) than in the posterior portion (3.78/g, P<0.01). The medial pterygoid had a mean spindle density of 4.43/g.


CONCLUSIONS
These results indicate a heterogeneous distribution of muscle spindles in the masticatory muscles with different morphologies or in different portions of the same muscle, depending on muscle fiber type and muscular architecture.
Department of Oral Anatomy and Physiology, Zunyi Medical College, Zunyi, China. 495454380@qq.com
Yue-rong
YR
Zhang
Jing
J
Liu
D006801:Humans; D008410:Masticatory Muscles / Q000294:innervation* / Q000502:physiology*; D009470:Muscle Spindles / Q000033:anatomy & histology* / Q000502:physiology