Bifurcated distal biceps brachii tendon coexisting with separated bicipital aponeurosis: a complex variational case report.

Variations appearing in biceps brachii muscle are common with accessory head, different origins, variant insertion, and different pattern of nerve innervation. However, variations appearing in both origin and insertion, and with other anomalous morphology at the same time are seldom. Here we report a complex variational case on the right arm of a 91-year-old Japanese female cadaver. The complex variations included (1) the biceps brachii muscle bifurcated at its distal ending; (2) the long head had its own tendon, which divided into two parts, i.e., a lateral part fused into the fascia between the brachioradialis and extensor carpi brevis, and a medial part attached to the radius about one centimeter ahead of the radial tuberosity; (3) the short head had an accessory origin from the shoulder capsule; (4) the bicipital aponeurosis was of two parts with an anterior superior layer formed by the long head and a posterior deep one formed by the short head; (5) the musculocutaneous nerve was especially underdeveloped that only innervated the coracobrachialis; (6) the existence of communicating branch between the musculocutaneous and median nerves, and the median nerve issued muscular branches to the biceps brachii and brachialis muscles, and (7) the brachioradial muscle had two accessory muscular bundles that originated from the fascia of the brachial muscle (proximal one) and from the bicipital aponeurosis (distal one).

Morphologic observation for anomalous patterns of the flexor carpi radialis muscle and atypical insertions: a proposal for a new classification.

In the present study, four types of variations of the flexor carpi radialis with accessory muscular bundles were classified depending on the origin of the accessory muscular bundle and relationships with the bicipital aponeurosis, biceps brachii, pronator teres, and coracobrachialis. Six types of insertions of the tendon of the flexor carpi radialis were also divided according to their inserted positions on the carpal and metacarpal bones. An accessory muscular bundle of the flexor carpi radialis was found in 4 (1 female and 3 males) of 68 cadavers (5.88%), with five examples in 136 arms (3.68%). It was bilateral in one cadaver and unilateral (two on the right and one on the left) in three. The insertion of the flexor carpi radialis tendon was not only on the proximal surface of the base of the second metacarpal bone but also on the third metacarpal bone, the tubercle of the trapezium, and the scaphoid. These findings and classifications are important in anatomical education, and have important significances in clinical diagnosis and therapies.

An anomalous case of the flexor carpi radialis with an excessive muscular bundle.

A variation of the flexor carpi radialis with an excessive muscular bundle was found on the right forearm of a Japanese male cadaver. The flexor carpi radialis had two heads, medial one arising from the medial epicondyle of the humerus, and the other, a variant excessive muscular bundle, arising from the bicipital aponeurosis deep at the medial edge of the tendon of biceps brachii. There was also a muscular slip between the pronator teres and lateral head of flexor carpi radialis. The insertion of the ending tendon of the flexor carpi radialis was also variant, which was not only inserted into the base of the second metacarpal bone, but into the proximal surface of the scaphoid and the tubercle of trapezium. The excessive muscular bundle might be a residual muscular slip which connects between the distal part of the biceps brachii and the initial part of the flexor carpi radialis during the early embryonic development.

The Embryonic Ascent of the Kidney Revisited.

Although the embryonic kidney's ascent is well established, the intermediate morphological changes that occur during the process are unclear. To evaluate the morphological events that accompany the kidney's ascent, we examined serial sagittal sections from 24 embryos at 5-7 weeks gestation. Six specimens had bilaterally ascending kidneys that were between the levels of the second to fifth lumbar vertebrae, and each kidney had a primitive renal cortex surrounding clusters of ampullae, which branched from the pelvis, and a dense tissue band that connected the renal cortex with the embryonic adrenal cortex or celiac ganglia, and there was no adipose capsule or renal artery. The tissue band contained abundant nerve twigs from the major splanchnic nerve; thus, it was conceivable that it was sufficiently rigid to support the length of the retroperitoneal tissue mass that included the embryonic adrenal cortex, celiac ganglia, and kidney. The lumbar vertebral body's height was much shorter than that of the ascending kidney. However, the lower vertebral column's curvature was often maintained, even when the kidneys had ascended. Therefore, vertebral column straightening was not the only factor required to drive the ascent. Together with the growth of the thorax and liver, the adrenal cortex, ganglia, and kidney appeared to change simultaneously at a position relative to the vertebrae. The renal artery established a connection to the renal cortex after the ascent. Evaluations of frontal sections from five additional specimens suggested that from its initial position, the kidney extended upwards between bilateral umbilical arteries. Anat Rec, 302:278-287, 2019. © 2018 The Authors. The Anatomical Record: Advances in Integrative Anatomy and Evolutionary Biology published by Wiley Periodicals, Inc. on behalf of Wiley-Liss, Inc.

Transparent model of temporal bone and vestibulocochlear organ made by 3D printing.

The vestibulocochlear organ is composed of tiny complex structures embedded in the petrous part of the temporal bone. Landmarks on the temporal bone surface provide the only orientation guide for dissection, but these need to be removed during the course of dissection, making it difficult to grasp the underlying three-dimensional structures, especially for beginners during gross anatomy classes. We report herein an attempt to produce a transparent three-dimensional-printed model of the human ear. En bloc samples of the temporal bone from donated cadavers were subjected to computed tomography (CT) scanning, and on the basis of the data, the surface temporal bone was reconstructed with transparent resin and the vestibulocochlear organ with white resin to create a 1:1.5 scale model. The carotid canal was stuffed with red cotton, and the sigmoid sinus and internal jugular vein were filled with blue clay. In the inner ear, the internal acoustic meatus, cochlea, and semicircular canals were well reconstructed in detail with white resin. The three-dimensional relationships of the semicircular canals, spiral turns of the cochlea, and internal acoustic meatus were well recognizable from every direction through the transparent surface resin. The anterior semicircular canal was obvious immediately beneath the arcuate eminence, and the topographical relationships of the vestibulocochlear organ and adjacent great vessels were easily discernible. We consider that this transparent temporal bone model will be a very useful aid for better understanding of the gross anatomy of the vestibulocochlear organ.

Time-saving and fail-safe dissection method for vestibulocochlear organs in gross anatomy classes.

Because the vestibulocochlear organs are tiny and complex, and are covered by the petrous part of the temporal bone, they are very difficult for medical students to dissect and visualize during gross anatomy classes. Here, we report a time-saving and fail-safe procedure we have devised, using a hand-held hobby router. Nine en bloc temporal bone samples from donated human cadavers were used as trial materials for devising an appropriate procedure for dissecting the vestibulocochlear organs. A hand-held hobby router was used to cut through the temporal bone. After trials, the most time-saving and fail-safe method was selected. The performance of the selected method was assessed by a survey of 242 sides of 121 cadavers during gross anatomy classes for vestibulocochlear dissection. The assessment was based on the observation ratio. The best procedure appeared to be removal of the external acoustic meatus roof and tympanic cavity roof together with removal of the internal acoustic meatus roof. The whole procedure was completed within two dissection classes, each lasting 4.5 hr. The ratio of surveillance for the chorda tympani and three semicircular canals by students was significantly improved during 2013 through 2016. In our dissection class, "removal of the external acoustic meatus roof and tympanic cavity roof together with removal of the internal acoustic meatus roof" was the best procedure for students in the limited time available. Clin. Anat. 30:703-710, 2017. © 2017Wiley Periodicals, Inc.

Simple ways to dissect ciliary ganglion for orbital anatomical education.

In the case of anatomical dissection as part of medical education, it is difficult for medical students to find the ciliary ganglion (CG) since it is small and located deeply in the orbit between the optic nerve and the lateral rectus muscle and embedded in the orbital fat. Here, we would like to introduce simple ways to find the CG by 1): tracing the sensory and parasympathetic roots to find the CG from the superior direction above the orbit, 2): transecting and retracting the lateral rectus muscle to visualize the CG from the lateral direction of the orbit, and 3): taking out whole orbital structures first and dissecting to observe the CG. The advantages and disadvantages of these methods are discussed from the standpoint of decreased laboratory time and students as beginners at orbital anatomy.

Abnormal veins around the heart with the closure of the coronary sinus ostium.

In a cadaveric dissection course at Akita University Graduate School of Medicine in 2014, we observed abnormal veins in a 72-year-old male who died of prostate cancer. The abnormality consisted of the following: closure of the opening of the coronary sinus (closure of the coronary sinus ostium), a persistent left superior vena cava (Lsvc), and a postaortic left brachiocephalic vein (Palbv). The shunt between the coronary sinus and left atrium was not observed. The blood of the coronary sinus flowed into an oblique vein of the left atrium, which was wide and reverse-funnel shaped, penetrated the pericardial sac then continued to the Lsvc. The anastomotic veins between the Lsvc and the (right) superior vena cava were seen to consist of two veins as follows: one was a left brachiocephalic vein, the other a dorsal postaortic left brachiocephalic vein (dorsal Palbv). The dorsal Palbv passed dorsally on the ligamentum arteriosum, and then passed between the ascending aorta and the trachea. The dorsal Palbv was thicker than the left brachiocephalic vein. We discuss the process of formation of these variations.

Fetal development of the mesonephric artery in humans with reference to replacement by the adrenal and renal arteries.

According to the classical ladder theory, the mesonephric arteries (MAs) have a segmental arrangement and persist after regression of the mesonephros, with some of these vessels becoming definitive renal arteries. To avoid interruption of blood flow, such a vascular switching would require an intermediate stage in which two or more segmental MAs are connected to a definitive renal artery. To examine developmental changes, especially changes in the segmental distribution of MAs, we studied serial paraffin sections of 26 human embryos (approximately 5-7 weeks). At 5-6 weeks, 1-2 pairs of MAs ran anterolaterally or laterally within each of the lower thoracic vertebral segments, while 2-5 pairs of MAs were present in each of the lumbar vertebral segments, but they were usually asymmetrical. The initial metanephros, extending along the aorta from the first lumbar to first sacral vertebra, had no arterial supply despite the presence of multiple MAs running immediately anterior to it. Depending on increased sizes of the adrenal and metanephros, the MAs were reduced in number and restricted in levels from the twelfth thoracic to the second lumbar vertebra. The elimination of MAs first became evident at a level of the major, inferior parts of the metanephros. Therefore, a hypothetical arterial ladder was lost before development of glomeruli in the metanephros. At 7 weeks, after complete elimination of MAs, a pair of symmetrical renal arteries appeared near the superior end of the metanephros. In conclusion, the MAs appear not to persist to become a definitive renal artery.

A study of fundamental courses in the great cardiac vein.

We studied an extremely rare great cardiac vein anomaly in a 65-year-old woman during dissection practice at the Akita University School of Medicine (2013). The great cardiac vein has two main roots, one accompanied by a left marginal vein that pours into the coronary sinus, and the other ascending along the anterior interventricular sulcus from the apex, and running over the circumflex branch of the left coronary artery. It then runs along the atrial side of the transverse sinus of the pericardium, and drains directly into the superior vena cava. No anastomosis between these veins was evident. The great cardiac vein might originate from two venous systems, one in the posterior wall of the left ventricle, and the other running along the anterior interventricular sulcus. These venous systems flow in the venous network of the left edge of the coronary sulcus. The former venous system always selected the course, which went to the coronary sinus in the venous network. The latter system may drain into one of the following four courses: the first one contacts the former course; the second passes to the transverse sinus of the pericardium and flows to the (right) superior vena cava; the third passes between a pulmonary trunk and ascending aorta from the dorsum of the pulmonary trunk, turns around in a ventral aspect, and then flows into the left superior vena cava; and the fourth flows to the anterior cardiac vein. The first of these belongs to the normal great cardiac vein, but the others are anomalous.

Human fetal topographical anatomy of the femoral triangle in relation with change in the hip joint position.

Fetal hip joint is characterized by its highly flexion and lateral rotation although adult anatomy of the femoral nerve and iliofemoral ligament suggested the medial rotation. To investigate topographical anatomy of the femoral nerve, artery and vein in the femoral triangle, we histologically examined 11 fetuses (15-37 weeks). The nerve-vessel topographical relation was basically similar to that in adults, but the fan-like nerve division was seen in the horizontal plane in the smaller specimens in contrast to that included in the sagittal plane in the larger specimens. The medial or internal rotation of the nerve division seemed to occur in late stage fetuses, at birth and at infancy. Blood supply to the head of the femur might be also accelerated by changes in the hip joint position.

Arterial system of the atrium in the human heart.

We dissected the atrial arterial system of 22 adult human hearts from donated cadavers. Atrial branches (ABs) of coronary arteries, more than 0.5 mm in diameter at their origin, were selected to trace systematically their origin and course. A total of 135 ABs were observed, of which 68 were from the circumflex branch, and 67 from the right coronary artery. The origins of ABs were classified into the following five regions where they arose from coronary arteries: (A) from the left aortic bulb to the one-third of the left auricle, (B) from the end of region A to the point of anastomosis of the coronary sinus (CS) with an oblique vein of the left atrium (OVLA), (C) from the end of region B to the opening of the CS, (D) from the end of region C to two-thirds of the right auricle, (E) from the end of region D to the right aortic bulb. With regard to the course of the ABs, they were classified according to the following 8 areas where they passed: (I) underneath Bachmann's bundle (BB); (II) the area connecting the right and left superior pulmonary veins; (III) the dorsal part of the interatrial septum; (IV) beside the OVLA; (V) the atrial side beside the CS; (VI) the ventral part of the interatrial septum; (VII) the dorsal wall of the left atrium; (VIII) on the dorsal surface of the right atrium. Thus, ABs showed various combinations of regions and courses.

Fetal development of the transverse atlantis and alar ligaments at the craniovertebral junction.

Although the fetal development of the craniovertebral junction has long been of major interest to embryologists from the viewpoint of segmentation, development of the associated ligaments has received scant attention. Using semiserial horizontal sections from 18 embryos and fetuses (six embryos with a crown-rump length (CRL) of 20-26 mm or ~6-7 weeks of gestation; five fetuses with a CRL of 32-58 mm or 8-9 weeks; seven fetuses with a CRL of 90-115 mm or 14-15 weeks) without any abnormalities of cartilage configuration such as atlas assimilation, we studied the ligamentous structures along and around the odontoid process of the axis. The transverse atlantis and alar ligaments originated from a common mesenchymal condensation possibly corresponding to the proatlas segment: the former started to develop slightly earlier than the latter, and the morphologies of both were established at 7 weeks of gestation. Development of the joint cavitation around the odontoid process began in the mid-anterior area at 6 weeks, but was not fully completed even at 15 weeks (115 mm CRL). The presumptive joint cavity expressed vimentin and CD34 and contained abundant CD68-positive macrophages. We always found a mid-anterior joint cavitation facing the basi-occipital, but the embryological meaning remained unclear. The apical ligament appeared most likely to originate from the notochord sheath. The notochord was exposed from the tip of the odontoid process toward the loose epidural tissue and entered the occipital bone, but was difficult to trace to the anterior surface of the basi-occipital.

Anomalous head of the brachial muscle penetrates the deltoid muscle.

We report here, for the first time a specimen in which the insertion of the deltoid muscle is divided into two parts, composing a canal. The brachial muscle was composed of medial, lateral, and anomalous heads. The anomalous head arose as a thin tendon from the surgical neck of humerus, passed through the canal, and then became confluent with the lateral head. The musculocutaneous nerve innervated the brachial muscle. The lateral head, but not the anomalous head, received a thin branch from the radial nerve.

A case of anomalous bronchial artery ramified from coronary artery.

There have been no anatomical reports on the origin of the bronchial artery derived from the coronary artery. In a 2006 cadaveric dissection course, an anomalous bronchial artery that reached the middle lobe of the right lung from the left coronary artery was observed in an 88-year-old Japanese man. In this specimen, the circumflex branch of the left coronary artery passed under the left auricle in the coronary sulcus and bifurcated to three branches (left marginal branch, posterior left ventricular branch, atrial branch), which were 3.2-3.4 mm in diameter. The atrial branch intersected on the surface of the great cardiac vein, ran along the oblique vein of the left atrium, and reached the atrial side of the transverse pericardial sinus, and then divided into two branches. One of them led to the right atrium. The other branch passed between two right superior pulmonary veins, which derived from superior and middle lobes of the right lung, respectively, through the hilum of the lung along the right superior pulmonary vein derived from the middle lobe, and finally became the bronchial artery in the middle lobe of the right lung. In the middle lobe, the bronchial artery divided into a thin branch along the pulmonary vein for the lateral segment, ran along the surface of the right middle bronchus, and then reached the medial segment, being wedged between the segmental bronchus and vein.

Observation of the upside-down stomach esophageal hiatal hernia in a cadaver.

In the course of a cadaveric dissection in 2006, an upside-down stomach esophageal hiatal hernia was observed in a 91-year-old Japanese woman with kyphosis who had died of brain infarction. There are 31 clinical reports of upside-down stomach esophageal hiatal hernia, but the vascular system was not analyzed in any of these cases. In this specimen, most of the stomach except the pyloric region passed through the esophageal hiatus (approximately 40 mm in diameter) with the greater omentum and into the hernial sac located dorsal to the heart in the thoracic cavity. The greater omentum was raised on the ventral region in the hernial sac and spread toward the upper abdomen through the esophageal hiatus from the sac, without any adhesion in the abdominal cavity. The tail of the pancreas and the spleen were located near the esophageal hiatus. No abnormality was observed in the heart or lungs. The celiac trunk and its main branches were normal, but the left and right gastric arteries, the short gastric artery and the left gastroepiploic artery passed into the hernial sac through the esophageal hiatus. This specimen was classified as the sliding type of esophageal hiatal hernia. We consider the excessive kyphosis of the vertebral column to likely be associated with the formation of such a highly advanced hernia.

Intersection patterns of human coronary veins and arteries.

Intersections between the coronary veins (CV) and arteries (CA) of 103 adult human hearts were mapped on the heart surface. Then the correlations of these intersection patterns to their localization were studied. Eight spots were selected where one of four major CV (anterior cardiac vein, middle cardiac vein, left posterior ventricular vein, and great cardiac vein) intersected with one of CA and their branches (right coronary artery, posterior interventricular branch, left posterior ventricular branch, circumflex branch, diagonal branch, and anterior interventricular branch). The great cardiac vein (GCV) ran beneath the anterior interventricular branch in 56 specimens out of 103, beneath the diagonal branch in 75 specimens out of 103, and beneath the circumflex branch in 36 specimens out of 103, while the other CV mostly ran over CA. The present observations suggest that the CV on the right side may be formed prior to CA, while the CV on the left side may be formed simultaneously with CA.

Anomalous venous system in the human heart.

In a 2002 cadaveric dissection course, a complex manner of rare variation was found in the abnormal venous system of the heart of an 88-year-old Japanese man who died of acute pneumonia. The superior vena cava and the left and right brachiocephalic veins were normal. In this case, a complex venous system existed as follows. (1) A left superior vena cava was persistent. (2) The innominate vein was present. It went upward between the ascending aorta and the pulmonary trunk, passed through the ventral side of the bifurcation of the pulmonary trunk, and then anastomosed with the left superior vena cava. The oblique vein of the left atrium, as a fibrous bundle, was connected to the junction of the left superior vena cava and the innominate vein in the pericardium. (3) The great cardiac vein was divided into two branches. One was located at the right side of the left coronary artery, forming the origin of the innominate vein. The other extended to the coronary sinus as a normal great cardiac vein. (4) The orifice of the coronary sinus on the right atrium was obliterated. (5) The abnormal orifice existed between the left atrium and the coronary sinus. The formation process and functional significance of such venous variations are discussed.

Observation of root variations in human coronary arteries.

In dissection courses conducted from 1999 through to 2003, five specimens were found to have coronary arteries with variant roots and branches, as follows: in specimens 1-4, roots of the right coronary artery (RCA) and right conus branch arose independently from the right aortic sinus (RAS); in specimen 5, the RCA and left coronary artery (LCA) originated from the RAS. The LCA pierced the upper part of the muscular interventricular septum and appeared on the surface, then dividing into the anterior interventricular and the circumflex branches. In the present study, we considered that the right conus arteries in specimens 1-4 were the remnant blood capillaries around the aorta towards the RAS in the embryonic stage. In specimen 5, the vessel near the left aortic sinus was poorly developed as a small thin artery. Instead, the LCA was developed from the anterior and posterior interventricular septal branches.

On unknown bone bridge and foramen of the atlas.

The atlas of a 52-year-old male Japanese cadaver, which had been removed and macerated, presented a bilateral unknown bone bridge forming a foramen (Case 1). The bone bridge connected the ponticulus lateralis (PL) and posterior (PP) to form an oval foramen between the superior roots of both ponticuli. The atlas of a 69-year-old male Japanese cadaver was found to have similar variations in situ (Case 2). In this case, the right bone bridge connected the superior root of the incomplete PL and the inferior root of the also incomplete PP to form a long ellipsoid foramen opening medially. The medial opening of the foramen was closed by a ligamentous connective tissue in situ. The condylar emissary vein passed this complete foramen to join the cervical epidural venous plexus. The similar bilateral foramen in case 1 was supposed to pass the same vein as in case 2. The bone bridge between the two ponticuli and the resulting foramen mentioned above have not been described previously, as far as we know. We propose that these structures be called the ponticulus interponticularis atlantis and the foramen atlantoideum interponticulare, respectively.