[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.
Zhang
Yue-rong
YR
Department of Oral Anatomy and Physiology, Zunyi Medical College, Zunyi, China. 495454380@qq.com
Liu
Jing
J
D006801:Humans; D008410:Masticatory Muscles / Q000294:innervation* / Q000502:physiology*; D009470:Muscle Spindles / Q000033:anatomy & histology* / Q000502:physiology