The inferior alveolar artery, vein and nerve send some branches to the molar teeth via the mandibular canal to the mental foramen. The present study attempted to define the presence and course of the mandibular canal in the mandible with the alveolar process by macroscopic cadaveric dissection and computerized tomography (CT) in order to provide information that might prevent injuries to vessels and nerves at risk during root canal treatment. We identified the position of the mandibular canal within a 30% ratio of the distance from inferior border of mandible to the apices of the root for 39 out of 131 sides (mesial root of first molar, 20%; distal root of first molar, 22.6%; mesial root of second molar, 27.8% and distal root of second molar, 47%) on panoramic X-ray observation. In one cadaver (male, 64 years old), the root apex of the second molar was in close proximity to the upper bony mandibular canal. Macroscopic dissection and computerized tomography showed that the main trunks of the inferior alveolar artery, vein, and nerve were in tight contact with the apex of the second molar. These observations of the anatomic course of the mandibular canal will be important to consider during root canal treatment of mandibular teeth.

Summary: The mylohyoid nerve (MN) displays several branches in the posterior, intermediate, and anterior region of the mylohyoid muscle (MM) as it courses on the internal surface of the mandibular body. Branches in the intermediate region were found in 66% of the cases (272 out of 413 sides). In the submandibular triangle, one or two large branches of the MN communicated with the lingual nerve at submandibular triangle and submental triangle in 1.45% of the cases (6 out of 413 sides). These distributions of nerve supply are an important in the operations of radical neck dissection on the submandibular triangle.The mandibular nerve divides into two branches, the lingual nerve (LN) and the inferior alveolar nerve (IAN), at the mandibular notch. The IAN descends to the mandibular nerve branches on the inner mylohyoid muscle (MM). Mandibular nerve has anastomotic branches connecting to the lingual nerve (LN) after leaving laterally from the foramen ovale (Clemente, 1985). Chorda tympani join the LN in the deep region behind the lateral pterygoid muscle. The IAN is also branched into the mylohyoid nerve (MN) at the mandibular foramen. There are a few communications between the MN and the LN in the submental triangle. Kameda (1952) has reported the MN communicated with the LN in 46.3% (74 out of 160 sides) of the cases.The communication rate of the LN and the MN in Kameda reports (1952) is high in compared to that of our data, however, this reports is no detailed in course, supply, and any region in two nerves. Radical neck dissection needs the detailed information of nerve supply in the submandibular triangle (Beahrs, 1977;Swift, 1970;Feldman and Applebaum, 1977). Trail and Lubritz (1974) also indicated complete removal of tumors on the submandibular gland required radical excision of tissue around them, including neck dissection. Therefore we observed nerve supply on submandibular triangle and submental triangle in detail. Materials and MethodsWe examined the mylohyoid nerve branches under a binocular microscopy, 413 sides of 272 mandibles from adult Japanese cadavers (161 males and 111 females; 141 both sides, 60 right side only and 71 left side only) for passage and supply. We also observed the communications between the mylohyoid nerve (MN) and the lingual nerve (LN) in the submandibular triangle and submental triangle. Using forceps, we removed the entire mucous membrane, the connective tissues of the mylohyoid muscle (MM), parts of the ramus of the submental arteries, and veins at submandibular triangle and submental triangle. In each case, the communications between the MN and the LN and their distribution were analyzed and photographed. ResultsWe observed the course and the communications between the mylohyoid nerve (MN) and the lingual 45 * Correspondence to: Iwao Sato,

An abnormal cleidohyoid muscle, an excess anterior belly muscle of the digastric and a levator thyroid gland muscle are reported in the suprahyoid and infrahyoid musculature of Japanese male cadavers (Case A) 65 years and (Case B) 46 years old. The muscle weight, cross-sectional area of the transverse muscle section, number of muscle fibers per mm2 and the average size of the muscle fibers of these abnormal muscles were compared with simmilar parameters of normal suprahyoid and infrahyoid muscles.

Detailed observation of the structure of filiform papillae (FP) and microvasculature of those papillae in Japanese Azuma mole were described. In the anterior and medial regions, FP was cylinder in shape with two processes. In the posterior region, it had a long, sharp conical shape. The microvascular casts showed two types of hairpin-shaped capillary loops on three regions of the tongue. In the anterior and medial regions, the end of the capillary loops were shaped like a spoon. In contrast, in the posterior region, it was knot-like end of capillary loop. Since the shape of capillary loop was more complex in the anterior and medial regions than that in the posterior region, it was speculated that the spoon-like end of capillary loops of the FP in the anterior and medial regions supply nutrients to the filiform papillary cells and may be related to the movement of the tongue during mastication in Japanese Azuma mole.

No abstract

Summary: Human skin has various distributions and arrangements of elastic fiber (EF). Previous reports did not dearlyshow the distribution of EF in the face skin because of various contents during aging. In this study, a color image analyzer indicated distribution of elastic, oxytalan, and muscle fibers in human face skin. During aging the muscle fiber size and the content of the EF decreased in the modiolus and inferior labial regions of the human skin, and the ratio of the EF was lower than that of oxytalan fiber in measured areas. That is, the dimension of oxytalan fiber may reflect the content of EF, and muscle has a role in the distribution of the EF in human face skin. In the deeper regions, small and large EF bundles were found near the sheath of gland and musdes. Therefore, face movement might be an important aspect to maintaining the EF content of human face skin.While elastic fiber is found in various organs, previous reports have not clearly shown the distribution of EF due to variations; a thickening (Mongtana, 1973), decrease in number and thickness (Mitchell, 1967), and no significance at light microscopic levels (Marshall, 1965), and also specific ultrastructural properties (Stadler et al., 1978;Tsuji and Hamada, 1981) during aging. The majority of previous observations were only obtained from a region beneath the epithelium. Deeper than this, the distribution of elastic fiber has not been examined. Deeper regions contained muscle fibers might change configuration.Our analysis permits more detailed information in a quantitative distribution of elastic fibers taking into consideration of age-related changes. Therefore, the purpose of this study was to determine the distribution of the elastic fiber in the human face skin from the epidermal area to deeper regions connected to muscle fibers and to relate these findings to morphological properties. Materials and MethodsTwenty adult humans were selected autopsy from donations (males, aged 27 to 70 years of ages) for a histochemical analysis at microscopic and scanning electron microscopic levels. The materials were removed rapidly and immediately fixed in 10% formalin for one day at 4°C. After being washed in water, they were dehydrated in absolute ethyl alcohol and then embedded in paraffin. Serial frontal sections were cut at a thickness of about 3 gm on a rotary microtome. Sections were stained using the following methods: (1) Elasficavan Gieson staining was performed to demonstrate the locations of elastic fibers and (2) Elastica-van Gieson staining after incubation in a preoxidizing solution (pH 1.5), including 0.3% KMn04 and 0.3% H2SO4, was performed to demonstrate oxytalan fibers (a modified version of the method of Fullmer, 1959). Serial sections were observed using a real color image system (Swallo II, Interquest, Osaka, Japan). This system was configured with a color image measurement system using a Victor video camera with control unit and a Digital VX color video monitor linked to alight microscope (Vanox-

Summary: Crown dimensions of the maxillary molars were measured in the koala (Phascolarctos cinereus). There were no significant differences in crown diameters between the first and second molars, however the fourth molars were reduced in all crown diameters. The third molar was smaller than the first or second molars in buccolingual crown diameters but there were no significant differences in mesiodistal crown diameters. It is proposed that the similar shapes of the first and second molars are associated with similar types of masticatory activity involving these teeth, The shape of the third molar, which is reduced in size buccolingually, may be linked to the koala's occlusal function which is characterized by a condylar action that leads to differences in movement between opposing anterior and posterior molar teeth during the occlusal stroke. The fourth molar, the smallest of the molar teeth in crown diameter, erupts significantly later than the other molars, and its reduction may be explained by the terminal and distal reduction theories. It is proposed that the pattern of molar morphology in the koala is associated with both masticatory activity linked to its characteristic occlusal function, as well as reflecting the sequence of tooth emergence.

In the neonatal and postnatal development of rat TMJ, tenascin-C and -X were detected in the muscle, bone matrix, connective tissue around the bone, and blood vessel of rats at E18 (18-days old embryo), 0-, and 5-days postnatal. The reaction of tenascin-X was also found in the connective tissue around the mandibular condyle. The mRNA of tenascin-C (600 bp) and -X (588 bp) was also detected in the developmental muscle with the level of tenascin-C mRNA moderately decreased during development. Therefore, tenascin-C and -X may have different effects on the connective tissue during development of TMJ.