Two case reports of the right-sided aortic arch.

Two cases of right aortic arch with the left subclavian artery as its last branch were found in cadavers of 66- and 80-year-old Japanese males during the 1995 and 1996 dissection for students at Tokyo Dental College. In both cases, the esophagus and trachea were surrounded by a vascular ring which consisted of the aortic arch and arterial ligament. The left common carotid artery arose from the ascending aorta as the first branch and crossed ventral to the trachea in a left cephalic direction. In The second branch of the aorta, which was the right common carotid artery, the aortic arch ran in a dorsal direction, passing between the esophagus and vertebra after branch out the right subclavian artery. The left subclavian artery arose dorsal to the esophagus, and there was an aortic diverticulum between the left subclavian artery and the descending aorta. The arterial ligament communicated between the left pulmonary artery and the arterial diverticulum. The trachea and esophagus were consequently encircled by the vascular ring. Both of the present cases were of the N-type, according to the classification by Adachi-Williams-Nakagawa (Group IIIB1 type by Stewart, 1964).

A rare muscular anomaly in the upper arm--the chondroepitrochlearis muscle with an aberrant type of the muscular arch of axilla.

A rare muscular anomaly was found in the right arm of a 92-year-old man at Nagoya University in 1995. The anomalous muscle had two heads, one ventral and one dorsal. The ventral head was a continuation of the abdominal part of the pectoralis major muscle, and the dorsal head arose from the lateral surface of the latissimus dorsi muscle. The two heads united at the medical surface of the upper third of the arm to form a common tendon, which descended on the medial surface of the upper arm parallel with a long tendon of the coracobrachialis muscle and attached to the medial epicondyle of the humerus. This anomalous muscle was supplied by the most caudal branch of the pectoral ansa (caudal pectoral nerve) and the intercostobrachial nerve (Th2). This pectoral nerve first innervated the ventral head, and next the greater part of the dorsal head. The intercostobrachial nerve (Th2) innervated a small part of the dorsal head. The present anomaly looked quite similar to the case reported by Yokoh as the coexistence of the chondroepitrochlearis and the dorsoepitrochlearis muscles. However, judging from the muscular origin, insertion and innervation, the ventral head was considered to be the chondroepitrochlearis muscle, whereas the dorsal head was not dorsoepitrochlearis muscle but an aberrant type of the muscular arch of axilla.

Examination of nerve distribution to masticatory muscles using a silicone permeation technique.

The detailed anatomical distribution of nerves throughout the human body has generally been studied by dissection of fixed cadavers in liquid. In this traditional method, it is difficult to maintain the position of nerves on their respective muscles. It is also difficult to keep the distributed form of the nerves. To understand the morphology of nerves, it is essential to determine their location and distribution precisely. In this study the masseter muscle was removed from a cadaver after fixation with formalin. The muscle was then permeated with silicone using the following procedure. The muscle fixed by 10% formalin was dehydrated with alcohol. After dehydration, alcohol was replaced with methylene chloride. The sample was permeated by silicone in a permeater. Following dissection, enamel was applied to the nerve by hand to fix its position. This new permeation method provided excellent localization of nerves innervating the muscle and has the added advantage of providing a three-dimensional structure of neural anatomy similar to the casting procedures used to visualize blood vessels.