OBJECTIVETo find out the characteristic topographic distribution of the muscle spindles in human masseter and temporal muscle, and to clarify the neurobiology roles of masticatory muscles during chew and adjusting mandibular position.

METHODSThe muscle spindles of masseter and temporal muscle on both sides of 5 human corpses fixed in formalin for more than 1 year were observed and quantitatively analyzed by picture analysis equipment.

RESULTSThe muscle spindles were maldistributed and spindles were commonly clustered in some individual portions, and the muscle spindle figures were diversiform, which were predominantly composed of the spindle simple and spindle complexes. The masseter spindles of the deep portion were obviously more than that of the superficial. Spindles of temporal muscle were concentrated in the anterior approach to the coracoid.

CONCLUSIONThe distribution of muscle spindles in the masseter and temporal muscle is heterogeneous, spindle density in the deep portion of masseter and the anterior of temporolis muscle is greater than others. The deep of masseter and the anterior of temporal muscle play an important part in maintaining mandibular position and balance.

Cytoskeleton ; Humans ; Mandible ; Masseter Muscle ; Masticatory Muscles ; Muscle Spindles ; Temporal Muscle

OBJECTIVETo investigate the characteristics in the topographic distribution of the muscle spindles in human masticatory muscles.

METHODSThe 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.

RESULTSThe 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.

CONCLUSIONThese 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.

Humans ; Masticatory Muscles ; innervation ; physiology ; Muscle Spindles ; anatomy & histology ; physiology

Hemangiomas are the most common benign tumors in infancy, occurring most often on cutaneous and mucosal surfaces. Although less than 1% of hemangiomas occur in skeletal muscle, 15% of intramuscular hemangiomas arise in the head and neck musculature. Less than 10 cases of the sternocleidomastoid muscle have been reported in the English literatures. The masseter muscle is most commonly involved in the head and neck. Clinically, these tumors are present as distinct, localized, rubbery swelling. Neck computed tomography scan with enhancement may suggest a vascular mass within the muscle while angiography may detect feeding arteries in large intramuscular hemangiomas. The treatment of the hemangiomas is based on location, accessibility, depth of invasion, age, and cosmetic considerations. The optimal treatment is complete wide resection including the cuff of surrounding muscle. We report a case of hemangioma that occurred in the sternocleidomastoid muscle along with a with literature review.
Angiography ; Arteries ; Head ; Hemangioma ; Hemangioma, Capillary ; Masseter Muscle ; Muscle, Skeletal ; Neck Muscles ; Neck

The management of chronic empyema remains still disturbing. These patients always have chances to exposure septic conditions. We presents 4 patients of chronic empyema with sepsis who underwent E-flap and Myoplasty with extrathoracic skeletal muscles between December 1994 and March 1997. Two patients who had BPF were treated with intercostal muscle flap as co-procedures. Intervals between first E-flap and second Myoplasty ranged from 5 to 10 months. There was no morbidity or mortality. We think these stepwise procedure offers a chance to terminate these debilitating disease.
Empyema* ; Humans ; Intercostal Muscles ; Mortality ; Muscle, Skeletal ; Sepsis*

OBJECTIVETo investigate the electromyographic activities of anterior temporalis (TA), masseter muscle (MM), digastric anterior (DA), sternocleidomastoid (SCM) at postural position (MPP) and various mandibular movements in prognathic patients.

METHODSThirty-two patients with prognathism were selected from the clinic of oral and maxillofacial surgery of China Medical University. 36 healthy college students with normal occlusion were selected as normal controls. A BioEMG II diagnostic system with BioFLEX surface electrode was used to record the electromyographic activities of the above muscles.

RESULTSCompared with the control group, the electromyographic activities of TA, SCM and DA in prognathic patients were higher in MPP. The electromyographic activities of TA, MM were significantly lower than the control group in clenching (P < 0.01). In protrusion, the electromyographic activities of TA, MM and SCM in prognathic patients were higher than the control group (P < 0.01). In retrusion, the electromyographic activities of TA, SCM in prognathic patients were higher than the control group (P < 0.01).

CONCLUSIONThe masticatory muscles electromyographic activity of prognathism is abnormal.

Adult ; China ; Electromyography ; Humans ; Male ; Mandible ; Masseter Muscle ; Masticatory Muscles ; Neck Muscles ; Prognathism

A 67-year-old man with a history of chronic obstructive pulmonary disease (COPD) underwent F-18 fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) for staging of gastric cancer. The projection images of F-18 FDG PET/CT showed intensely increased F-18 FDG uptake in the anterior neck, chest wall, and upper abdomen. We suspected distant metastases of cervical lymph nodes, ribs, and peritoneum in gastric cancer. However, the transaxial images of F-18 FDG PET/CT showed abnormal F-18 FDG uptake in scalene muscles of anterior neck, intercostal muscles of chest wall, and diaphragm of upper abdomen. Patients with COPD use respiratory muscles extensively on the resting condition. These excessive physiologic use of respiratory muscles causes increased F-18 FDG uptake as a result of increased glucose metabolism. The F-18 FDG uptake in respiratory muscles of gastric cancer patient with COPD mimicked distant metastases in cervical lymph nodes, ribs, and peritoneum.
Abdomen ; Aged ; Diaphragm ; Electrons ; Glucose ; Humans ; Intercostal Muscles ; Lymph Nodes ; Metabolism ; Muscles ; Neck ; Neoplasm Metastasis* ; Peritoneum ; Positron-Emission Tomography and Computed Tomography ; Pulmonary Disease, Chronic Obstructive ; Respiratory Muscles* ; Ribs ; Stomach Neoplasms* ; Thoracic Wall

BACKGROUND: Muscle relaxants induce vascular smooth muscle relaxation by inducing synthesis of the prostaglandins that influence vasomotor tone. However, the effects of muscle relaxants on endothelial cells and tissues following injury by reactive oxygen species (ROS) are unclear. We tested the effects of the muscle relaxants vecuronium and rocuronium on impaired acetylcholine (ACh)-induced relaxation following induction of ROS in rabbit aorta in vitro. METHODS: Isolated rabbit abdominal aortic ring segments were pretreated with vecuronium or rocuronium at 10(-4), 3 x 10(-4), 10(-3) or 3 x 10(-3) M, with or without inhibitors of Cu/Zn superoxide dismutase (diethyldithiocarbamate; DETCA, 0.8 mM) or catalase (3-amino-1,2,4-triazole; 3AT, 50 mM). All groups of aortic rings were then exposed to ROS generated by electrolysis in the organ bath medium (Krebs-Henseleit solution). The effects of vecuronium and rocuronium on ROS-induced impairment of relaxation induced by ACh (10(-6) M) were assessed. RESULTS: Aortic rings treated with vecuronium or rocuronium at 10(-4), 3 x 10(-4), 10(-3) or 3 x 10(-3) M preserved the capacity for ACh-induced endothelial relaxation following ROS exposure in a dose-dependent manner. Pretreatment with DETCA partially inhibited the protective effects of vecuronium and rocuronium on ACh-induced relaxation (P < 0.001), but pretreatment with 3AT had no effect. CONCLUSIONS: Muscle relaxants protected the endothelium in isolated rabbit abdominal aorta from free-radical injury in a dose-dependent manner. These results suggest that vecuronium and rocuronium may act as superoxide anion scavengers.
Acetylcholine ; Antioxidants* ; Aorta ; Aorta, Abdominal ; Baths ; Catalase ; Electrolysis ; Endothelial Cells ; Endothelium ; Muscle, Smooth, Vascular ; Muscles* ; Prostaglandins ; Reactive Oxygen Species* ; Relaxation ; Superoxide Dismutase ; Superoxides ; Vecuronium Bromide

PURPOSE: To compare the size of the masseter and lateral pterygoid muscle between the affected and the unaffected side of the patients who have the chief complaints of the mandibular asymmetry. MATERIALS AND METHODS: Twenty two patients (male: 4, female: 18, average age: 21.3 year-old) were radiographed using posterior-anterior (P-A) cephalography and computed tomography (CT). On P-A cephalography, the degree of deviation was determined by the distance from the mentum to the vertical reference line through the crista galli and the anterior nasal spine. On the scanned tracing papers of the maximum cross-sectional area of the masseter and lateral pterygoid muscle using axial CT images, the pixel number was measured. The ratio of the affected : unaffected sides were obtained. For the masseter and lateral pterygoid muscle, the relationship between the muscular volume and degree of skeletal hypoplasia was studied. RESULTS: The half cases showed no skeletal asymmetry. The lateral pterygoid muscle of the affected side was larger significantly than unaffected side (p.0.05). However, there was no significant difference between two sides in the cases of skeletal asymmetry. There was only significant difference in the cases without skeletal asymmetry (p.0.05). CONCLUSIONS: To some extent, the slight mandibular hypoplasia could affect the growth of some masticatory muscles.
Chin ; Facial Asymmetry ; Female ; Humans ; Masticatory Muscles* ; Pterygoid Muscles ; Spine

Sex steroids influence the maintenance and growth of muscles. Decline in androgens, estrogens and progesterone by aging leads to the loss of muscular function and mass, sarcopenia. These steroid hormones can interact with different signaling pathways through their receptors. To date, sex steroid hormone receptors and their exact roles are not completely defined in skeletal and smooth muscles. Although numerous studies focused on the effects of sex steroid hormones on different types of cells, still many unexplained molecular mechanisms in both skeletal and smooth muscle cells remain to be investigated. In this paper, many different molecular mechanisms that are activated or inhibited by sex steroids and those that influence the growth, proliferation, and differentiation of skeletal and smooth muscle cells are reviewed. Also, the similarities of cellular and molecular pathways of androgens, estrogens and progesterone in both skeletal and smooth muscle cells are highlighted. The reviewed signaling pathways and participating molecules can be targeted in the future development of novel therapeutics.
Aging ; Androgens ; Estrogens ; Gonadal Steroid Hormones* ; Muscle, Skeletal ; Muscle, Smooth ; Muscles ; Myocytes, Smooth Muscle ; Progesterone ; Sarcopenia* ; Steroids

OBJECTIVETo analyze changes of myoelectrical activity of anterior funicle of temporal muscle (TA) and masseter muscle (MM) after raising vertical distance of occlusion by flat bite plate during treatment of deep overbite in order to approach an optimal raised vertical distance.

METHODSA total of 70 persons were selected and divided into two groups: Experiment group (36 patients) with deep overbite and control group (34 persons) with individual normal occlusion. The experiment group was subdivided into three groups that were respectively raised D, D+2 mm and D+4 mm (D means free way space, mm). Electromyologram (EMG) was utilized to measure the average peak potential of TA and MM on quiescent condition before treatment and two weeks after wearing flat bite plate.

RESULTS1) Before treatment, the average peak potential of experiment group was obviously higher than that of the control group (P<0.05). 2) After two weeks the potential of TA and MM of all persons in experiment group was obviously lower than before (P<0.05), the degree between the group D+2 mm and the group D+4 mm was not manifestly different, but both of the two groups were more obvious than the group D.

CONCLUSIONThe raised vertical distance of occlusion by flat bite plate, which exceeded free way space, was favourable to the functional recovery of masticatory muscles.

Dental Occlusion ; Humans ; Masseter Muscle ; Masticatory Muscles ; Overbite ; Vertical Dimension