An Extremely Rare Case of Intestinal Malrotation with an Absent Inferior Vena Cava.

We present a case of intestinal malrotation with an absent inferior vena cava, which was found in a cadaver during a dissection course in our medical school. The intestinal malrotation was Amir-Jahed type 2, with the large intestine on the right side and the small intestine on the left side of the abdominal cavity. The descending colon was fixed on the right side of the posterior abdominal wall and continued into the pelvic cavity from the right side. The cadaver also had a venous system anomaly. The pre-renal segment of the inferior vena cava, which is a section between the renal vein and the hepatic vein, was absent. The inferior vena cava connected to the azygos vein after being joined by bilateral renal veins. The only hepatic segment of the inferior vena cava, which was posterior to the liver and received hepatic veins, penetrated the diaphragm and flowed into the right atrium. To our knowledge, this is the first report of these two anomalies appearing concurrently. We discuss the details of this case and the embryological considerations.

Anatomical study of the incisivus labii superioris and inferioris muscles in non-human primates.

The facial muscles have significant roles for vocalization, feeding, and facial expression in both human and non-human primates. Of these, the anatomy of the incisivus labii superioris (ILS) and incisivus labii inferioris (ILI), which are considered as the accessory bundle of the orbicularis oris (OO) in humans, has rarely been documented in the literature. Our current understanding of the function of the ILS and ILI is that they probably retract the upper and lower lips. Also, there is no account of these muscles in non-human primates in the current literature. The aim of this study was to reveal the ILS and ILI in non-human primates. Five Macaca fascicularis, one Macaca fuscata, one Macaca fuscata yakui, and one Pan troglodytes were dissected. Seven formalin-fixed cadavers and one fresh cadaver were included. Both the ILS and ILI were observed in all specimens. The ILS originated from the incisive fossa of the maxilla and inserted into the OO. The mentalis (MT) and ILI arose from the incisive fossa of the mandible and inserted into the OO and the skin of the chin area. The MT and ILI in the P. troglodytes examined were thicker than in the other three non-human species, and the ILS and ILI in the three macaques were similar in shape to those of humans. The difference of these muscles may result in different functions of the lip such as during vocalization, feeding, and facial expression.

A novel method with which to visualize the human sinuatrial node: Application for a better understanding of the gross anatomy of this part of the conduction system.

For various clinical/surgical procedures, it is important to accurately understand the location of the sinuatrial node (SAN). Therefore, this study's goal was to develop a new and simple method to visualize the SAN in human hearts. A total of 16 formalin-fixed human hearts were used in the study. After the epicardium was removed, the fat tissue on the myocardium's surface was brushed and removed in a solution of 40°C water with a surfactant to show the SAN's location. Once the structure considered to be the SAN was observed, histological observation was conducted with Masson's trichrome staining to confirm its identity. The working myocardium, SAN branch of the coronary artery, and the structure believed to be the SAN were observed in all specimens. Histological analysis confirmed this structure to be the SAN. We believe that the method described herein might contribute to a better understanding of the SAN's morphologic features and serve as an improved teaching aide. Clin. Anat. 33:232-236, 2020. © 2019 Wiley Periodicals, Inc.

Bilateral Lateral Costal Branches of the Internal Thoracic Arteries: A Case Report.

We report a case of bilateral lateral costal branches (LCB) of the internal thoracic artery (ITA). On the left side, the ITA branched from the subclavian artery as a common trunk with the thyrocervical trunk. The left LCB flew into the collateral branch of the fifth intercostal artery after reaching the upper end of the sixth rib and after exiting the left ITA at the upper part of the first rib. The left ITA was disconnected near the second rib because it had been used for coronary artery bypass surgery. The right ITA arose from the anterior surface of the right subclavian artery just after the right ITA diverged from the brachiocephalic artery. The right LCB reached the upper end of the fifth rib and flew into the collateral branch of the fourth intercostal artery. The right ITA descended along the back of the costal cartilages as usual. The mechanism of the development of the LCB is thought to be due to a lateral longitudinal anastomosis connecting the inter-node arteries arising from the dorsal aorta during the embryonic phase. More anatomical and embryological studies are necessary to further elucidate this variant arterial branch.

First Report of a Bifid Mandibular Canal Containing a Large Vein Draining into the Anterior Jugular Vein.

The bifid mandibular canal (BMC) is an anatomical variant of the mandible that is often observed on cone-beam computed tomographic images. We identified a BMC during routine cadaveric dissection. The upper mandibular canal contained the inferior alveolar nerve and artery, and the lower mandibular canal contained a large inferior alveolar vein. This latter vein left the mandible through a lateral lingual foramen and joined the anterior jugular vein. Additionally, this vein gave rise to small tributaries to the mental foramen and anterior surface of the mandible from the second mandibular canal. To our knowledge, this is the first report illustrating the contents of a BMC and drainage of a vein into the large anterior jugular vein.

A Retroaortic Left Renal Vein in a Female Cadaver.

We encountered a case of retroaortic left renal vein (RLRV) during an anatomical dissection course at our medical school in 2017. The case was a female cadaver who was 88 years old at death. Six roots of the left renal vein (RV) arose from the hilus of the kidney and joined to form one left renal vein, crossed dorsal to the abdominal aorta (AA) at the level of the second lumbar vertebra, and then drained into the inferior vena cava (IVC). Two roots joined at the right renal hilus to become the right RV to then drain into the IVC at the level of the first lumbar vertebral body. The reported frequency of RLRV is approximately 2%. Embryologically, the normal anastomosis of the left and right sub-cardinal veins results in the left RV traveling on the ventral surface of the AA. However, in the case presented here, the left RV traveled on the dorsal side of the AA due to the anastomosis of the left and right supra-cardinal veins and regression of the anastomosis between the left and right sub-cardinal veins. If both the dorsal and ventral anastomoses remain, the left RV travels on the dorsal and ventral sides of the aorta. Some of the clinical problems reported in association with RLRV are hematuria and abdominal pain, and the risk of damaging the RLRV during surgery of the posterior abdominal wall. Venous variants as reported herein should be kept in mind when interpreting imaging of the posterior abdominal wall or performing surgery or other invasive procedures near the RLRV.

Anatomical Study of the Extreme Lateral Transpsoas Lumbar Interbody Fusion with Application to Minimizing Injury to the Kidney.

Objective Since the extreme lateral lumbar interbody fusion procedure was first reported by Ozgur in 2006, a large number of clinical studies have been published. Anatomical studies which explore methods to avoid visceral structures, such as the kidney, with this approach have not been examined in detail. We dissected the retroperitoneal space to analyze how the extreme lateral transpsoas approach to the lumbar spine could damage the kidney and related structures. Methods Eight sides from four fresh Caucasian cadavers were used for this study. The latissimus dorsi muscle and the thoracolumbar fascia were dissected to open the retroperitoneum. The fat tissue was removed. Steel wires were then put into the intervertebral disc spaces. Finally, the closest distance between kidney and wires on each interdiscal space was measured. Results The closest distance from the wire in the interdiscal space on L1/2, L2/3 and L3/4 to the kidney ranged from 13.2 mm to 32.9 mm, 20.0 mm to 27.7 mm, and 20.5 mm to 46.6 mm, respectively. The distance from the kidney to the interdiscal space at L4/5 was too great to be considered applicable to this study. Conclusions The results of this study might help surgeons better recognize the proximity of the kidney and avoid injury to it during the extreme lateral transpsoas approach to the lumbar spine.

Anatomical Study of the Zygomaticofacial Foramen and Its Related Canal.

The zygomaticofacial branch (ZFb) of the zygomatic nerve passes through the lateral wall of the orbit anterolaterally and traverses the zygomaticofacial foramen (ZFFOUT). However, in terms of intraorbital course, only a few studies have focused on the orbital opening of the ZFb (ZFFIN) and related canal. Therefore, this study aimed to locate the orbital opening and exit of the ZFb of the zygomatic nerve. Twenty sides from 10 fresh frozen cadaveric Caucasian heads were used in this study. The vertical distance between inferior margin of the orbit and ZFFIN (V-ZFFIN), the horizontal distance between the lateral margin of the orbit and ZFFIN (H-ZFFIN), diameter of the ZFFIN (D-ZFFIN), the vertical distance between the inferior margin of the orbit and ZFFOUT (V-ZFFOUT), the horizontal distance between the lateral margin of the orbit and ZFFOUT (H-ZFFOUT), and the diameter of the ZFFOUT (D-ZFFOUT) were measured, respectively. The ZFFIN were located 5.1 ±â€Š2.0 mm superior to the inferior margin of the orbit and 4.3 ±â€Š1.6 mm medial to the lateral margin of the orbit. The ZFFOUT was located 1.2 ±â€Š2.9 mm inferior to the inferior margin of the orbit and 1.1 ±â€Š3.0 mm lateral to the lateral margin of the orbit. The diameter of the ZFFOUT was significantly larger than that of the ZFFIN. Additional knowledge of the zygomatic nerve and its branches might decrease patient morbidity following invasive procedures around the inferolateral orbit.

A Case of Duplicated Right Vertebral Artery.

We encountered a case of duplicated right vertebral artery during an anatomical dissection course for medical students in 2015. Two vertebral arteries were found in the right neck of a 91-year-old female cadaver. The proximal leg of the arteries arose from the area between the right subclavian artery and the right common carotid artery that diverged from the brachiocephalic artery. The distal leg arose from the right subclavian artery as expected. The proximal leg entered the transverse foramen of the fourth cervical vertebra and the distal leg entered the transverse foramen of the sixth cervical vertebra. The two right vertebral arteries joined to form one artery just after the origin of the right vertebral artery of the brachiocephalic artery entered the transverse foramen of the fourth cervical vertebra. This artery then traveled up in the transverse foramina and became the basilar artery, joining with the left vertebral artery. We discuss the embryological origin of this case and review previously reported cases.

Novel Cadaver Injection Method Using Latex and Magnetic Fluid.

Vascular injection into extracted tissue may be associated with leakage due to excessive local injection pressure. Historically, this complication has been impossible to resolve because the injection pressure has been the only available force with which to send the agent to the peripheral vasculature. We have developed a new vascular injection method that utilizes a material affected by magnetic force and is therefore not solely dependent upon the injection pressure. We mixed the same weights of latex and magnetic fluid and injected the solution into the arterial stump of an extracted tissue specimen. Next, we used a permanent magnet to attract the agent into the peripheral vasculature. We repeated the injection and magnetic application until no further fluid could be injected. We used this method in 20 formalin-fixed tissue specimens. The vessels were clearly observable through to the peripheral areas, and leakage from the injected artery was minimal. This new agent has several beneficial characteristics: it is X-ray impermeable, is durable in the face of chemical insult, and allows for easy visual observation. The injected tissue can be studied for X-ray film examination, tissue clarification, and gross anatomical dissection. Additionally, this method can be applied to both fresh and formalin-fixed tissue. We consider that this method has the potential to expand the applications of injection studies.

Anatomical and Radiological Analyses of L-shaped Kidney with Vascular Anomalies.

L-shaped kidney is a congenital anomaly. The disorder results in the kidney appearing very similar in shape to horseshoe kidney (also a congenital anomaly), but either the right or left kidney is located at a position lower than the other kidney. In this report, we describe a woman with L-shaped kidney, identified during anatomical dissection, and compare the findings with clinical data obtained before her death. We discuss the embryology of L-shaped kidney based on detailed anatomical data on the kidney and its vascular system obtained by means of gross anatomical, radiological, and histological examinations. Our findings indicate the importance of detailed anatomical information when planning surgical procedures in patients with fused kidneys, as well as kidney transplantation, resection of renal carcinoma, or surgical treatment of abdominal aortic aneurysm.

Unusual muscle of the anterior neck: cadaveric findings with surgical applications.

The omohyoid muscle typically has an inferior belly originating from the superior border of the scapula, and then passes deep to the sternocleidomastoid muscle where its superior belly passes almost vertically upward next to the lateral border of sternohyoid to attach to the inferior border of the body of the hyoid bone lateral to the insertion of sternohyoid. Herein, we report an unusual variant of the omohyoid and sternohyoid muscles. As the omohyoid muscle is commonly used as a surgical landmark during neck dissections, knowledge of its variations such as the one described in the current report is important to surgeons.

First Report of Tripled Retromolar Foramina.

The retromolar foramen (RMF) is the bony entrance of the retromolar canal, through which a neurovascular bundle runs. It is essential to locate such anatomic variants in a patient in order to avoid complications in surgery, implant placement, or anesthesia of the area. To our knowledge, there has only been one case report of supernumerary RMF, which reported one bilateral doubled retromolar foramina and one doubled left RMF. We present an extremely rare case in which a right triple RMF was observed on cone beam computed tomography in a cadaver. Diameters of the RMF were 0.8 mm, 1.0 mm and 1.1 mm, respectively. Distances from the distal edge of the third molar were measured as 4.0 mm, 3.6 mm, and 0.5 mm, respectively. RMF was not found on the left side of the mandible.

A Novel Method for Observation of the Mandibular Foramen: Application to a Better Understanding of Dental Anatomy.

Cone-beam computed tomography gives us much useful morphological information about the mandibular bone. Many studies of the mandible include findings from this technique. However, there have been no endoscopic studies of the mandible. Sixteen sides of eight dry mandibles resected from cadavers (age range 38-83 years) were examined by endoscopy. The head of the endoscope was 2.0 mm in diameter. We examined the mandibular foramen, lingula, mylohyoid groove, and mandibular canal. The mylohyoid grooves showed variations such as double grooves and canals. The mandibular lingula was located superior or medial to the the mandibular foramen. In a single case, the medial wall inside the mandibular canal showed a porous surface. The retromolar canal was observed in three sides. None of the images in the present study have been seen in other studies. Observation of the retromolar canal from the mandibular canal in particular can help dental students as well as oral and maxillofacial surgeons to understand its morphology. Anat Rec, 2017. © 2017 Wiley Periodicals, Inc. Anat Rec, 300:1875-1880, 2017. © 2017 Wiley Periodicals, Inc.

Undetected Small Accessory Mental Foramina Using Cone-Beam Computed Tomography.

INTRODUCTION: The accessory foramina could not be identified on some imaging modalities such as surface-rendered images. The purpose of this study was to investigate the ability of surface-rendered images in detecting these foramina. MATERIALS AND METHODS: We analyzed 20 accessory mental foramina (AMF) in nine mandibles removed from cadavers with cone-beam computed tomography (CBCT) and assessed in surface-rendered images. All AMF were divided into three groups depending on their visibility. RESULTS: Group 1 included AMF that were clearly visible as foramina, Group 2 were not clearly visible but could be recognized with concave parts, and Group 3 were not visible and the smooth surface of the bone was observed. Group 1 ranged from 1.3 to 5.1 mm2, Group 2 from 0.3 to 3.8 mm2, and Group 3 from 0.2 to 1.1 mm2. A statistically significant difference in the mean size between Groups 1 and 3 was observed. Even if the AMF are smaller (e.g., 1 mm in diameter), they should still be avoided to prevent injury. CONCLUSIONS: The clinician should be aware that smaller foramina might not be detected on these images.

Radiological and Microsurgical Anatomy for Variation of the Mandible: Comparative Study of Human and Macaca fascicularis.

Recent studies using cone-beam computer tomography (CBCT) have added to our understanding of anatomical variation in the mandible of humans. However, the distribution of nerves cannot be revealed by CBCT. There have been investigations of the distribution of nerves relating to the mandible, but some proposed causes of these variations remain controversial. In this study, we observed a total of 10 sides from five mandibles of Macaca fascicularis of unknown age and sex using CBCT and dissection under stereomicroscopy. Nine of the 10 sides had two mental foramina in each side. Innervation by the mental nerves depended on the locations of those foramina. The long branch to the mandibular angle ran with a branch of the facial artery, which joined the mental artery in all 10 sides. Five specimens had a median perforating canal in the mandibular bone. In addition, a branch of the sublingual artery, which joined with the small branches of the submental artery, entered the mandibular bone from the median lingual foramen. This foramen was located in the lower part of the mandibular symphysis and passed via the median perforating canal to exit from the median labial foramen, also located in the lower part of the mandibular symphysis. We speculate that the median perforating canal of the mandible, rarely found in humans, is the remnant of the feeding artery of the fetal mandible, and in M. fascicularis is seen in all specimens because they have no mental protuberance. Anat Rec, 300:1464-1471, 2017. © 2017 Wiley Periodicals, Inc.

Morphometric Study of a Huge Elongated Styloid Process.

An elongated styloid process (ESP) is present in 4% of the general population. It is sometimes found incidentally by panoramic radiography or computed tomography in the clinical setting. Few detailed morphometric studies of this phenomenon have been performed, however, especially regarding its histologic aspects. During anatomic dissection of a 71-year-old man who had died from cardiac failure and whose body had been donated to our department for medical student training, an ESP was found while disconnecting the stylohyoid muscle from the hyoid bone. It measured 88 mm in length. After resection, the ESP was examined using computed tomography and was assessed histologically. The results showed that it consisted of bone and cartilage. It was composed mainly of three types of cartilage with a beaded appearance. Masson trichrome staining revealed scattered collagenous fibers around the cartilage. Although ESP is not uncommon in the clinical setting, this huge ESP found during a dissection course and its detailed histologic investigation were considered sufficiently valuable to be reported.

An anatomical study of the transversus nuchae muscle: Application to better understanding occipital neuralgia.

The transversus nuchae muscle appears inconsistently in the occipital region. It has gained attention as one of the muscles composing the superficial musculoaponeurotic system (SMAS). The purpose of this study was to clarify its detailed anatomical features. We examined 124 sides of 62 cadavers. The transversus nuchae muscle was identified when present and examined after it had been completely exposed. We also examined its relationship to the occipital cutaneous nerves.The transversus nuchae muscle was detected in 40 sides (40/124, 32.2%) of 26 cadavers; it was present bilaterally in 14 and unilaterally in 12. It originated from the external occipital protuberance; 43% of the observed muscles inserted around the mastoid process, and 58% curved upward around the mastoid process and became the uppermost bundle of the platysma. In one case, an additional bundle originated from the lower posterior border of the sternocleidomastoid muscle and coursed obliquely upward along with platysma. Ninety percent of the muscles ran below the sling through which the greater occipital nerve passed; 65% of the lesser occipital nerves ran deep to the muscle, and 55% of the great auricular nerves ran superficial to it. Our observations clarify the unique anatomical features of the transversus nuchae muscle. We found that it occurs at a rate similar to that described in previous reports, but its arrangement is variable. Further investigations will be performed to clarify its innervation and other anatomical features. Clin. Anat. 30:32-38, 2017. © 2016 Wiley Periodicals, Inc.

Communicating branches between lingual and hypoglossal nerve: observation using Sihler's staining technique.

PURPOSE: Many dental procedures are at risk of injuring the lingual nerve. We performed this study to better elucidate the microanatomy that exists between the ipsilateral lingual and hypoglossal nerves so that iatrogenic injury can be avoided. METHODS: Adult human cadaveric tongues (ten sides) underwent Sihler's staining to identify the microanatomy between the lingual and hypoglossal nerves. RESULTS: The lingual nerve entered the middle part of the anterior two-thirds of the tongue from its lateral side and divided into two to four thick branches. These branches were then disseminated to the anterior, middle, and posterior parts of the anterior two-thirds of the tongue via 7-14 thin nerve bundles as terminal branches. The hypoglossal nerve entered the tongue at the posterior border of its anterior two-thirds and traveled forward to the apex of the tongue on all sides. All specimens were found to have communicating branches between the lingual and hypoglossal nerves at its anterior, middle, and posterior thirds. CONCLUSIONS: Our results indicate that the ipsilateral lingual and hypoglossal nerves constantly have three connections on each side between them. This knowledge might aid the dentist in minimizing iatrogenic nerve injury.