Bifurcation of the Brachial Artery into Brachioradial and Brachioulnar Arteries in the Proximal Arm: Case Report and Clinical Significance

During anatomical dissection of fifty donors in the 2020 undergraduate first-year anatomy course at the Uniformed Services University of the Health Sciences, a high origin of the radial and ulnar arteries, also known as a brachioradial artery and a brachioulnar artery, was observed on the left arm of a 90 year-old White female donor. The bifurcation of the brachial artery occurred in the proximal third of the arm. Both the left brachioradial and left brachioulnar arteries ran superficial and medial to the biceps brachii muscle. The brachioulnar artery continues as the UA in the forearm, ran superficial and lateral to the flexor carpi ulnaris muscle, traversed the flexor retinaculum, and continued to form the superficial arterial palmar arch. The brachioradial artery ran deep to the pronator teres muscle and continued as the RA in the forearm. It presented with an atypical branching pattern and was tortuous until it reached the hand. On the dorsum of the hand, the radial artery runs superficial to the first dorsal interosseous muscle, parallel to the first metacarpal bone. It also reached the palmar side of the hand in an unusual manner. Medical professionals, especially radiologists, orthopedic and vascular surgeons, need to be aware of these variations to avoid iatrogenic injuries during normal procedures, such as venipuncture and intravenous injections. Knowledge of these variations is also important during invasive procedures, such as elbow reconstructive surgery, percutaneous brachial catheterization, and when creating an arteriovenous fistula using the radial artery. When such variations are suspected, Doppler and angiogram studies are necessary

Accessory Lateral Head of the Right Gastrocnemius Muscle in a 65 year-old White Male Donor

The three muscles that form the calf muscle or triceps surae include the soleus muscle, the gastrocnemius muscle, and the plantaris muscle. Generally, the gastrocnemius muscle consists of a larger medial head and relatively smaller lateral head. It is responsible for plantar flexion of the foot. The lateral head arises from the posterior lateral femoral condyle and the larger medial head originates from the posterior medial femoral condyle. The medial and lateral heads of the gastrocnemius muscle along with the soleus muscle combine to form the Achilles tendon, which inserts onto the posterior surface of the calcaneus. Since the gastrocnemius muscle crosses three joints including the knee and subtalar joints, it can be vulnerable to injury, especially in mature athletes who experience sudden and swift changes in direction associated with muscular overstretching. Other causes of gastrocnemius muscle injury include maximal knee extension and full ankle dorsiflexion. Since the muscle is already prone to injury, anatomical variations of the gastrocnemius muscles may be symptomatic. With muscle variations, there are potential implications and effects on the other structures within the popliteal fossa. Many different anatomical variations have been identified during routine dissections and reported in the literature. Understanding details of these variations is important for diagnostic, surgical and clinical practice and patient management. Here we report on a 65-year-old White Male cadaveric donor with an accessory lateral head of the gastrocnemius muscle found incidentally during a routine dissection

Testing Equid Body Mass Estimate Equations on Modern Zebras-With Implications to Understanding the Relationship of Body Size, Diet, and Habitats of Equus in the Pleistocene of Europe

The monodactyl horses of the genus Equus originated in North America during the Pliocene, and from the beginning of the Pleistocene, they have been an essential part of the large ungulate communities of Europe, North America and Africa. Understanding how body size of Equus species evolved and varied in relation to changes in environments and diet thus forms an important part of understanding the dynamics of ungulate body size variation in relation to Pleistocene paleoenvironmental changes. Here we test previously published body mass estimation equations for the family Equidae by investigating how accurately different skeletal and dental measurements estimate the mean body mass (and body mass range) reported for extant Grevy's zebra (Equus grevyi) and Burchell's zebra (Equus quagga). Based on these tests and information on how frequently skeletal elements occur in the fossil record, we construct a hierarchy of best practices for the selection of body mass estimation equations in Equus. As a case study, we explore body size variation in Pleistocene European Equus paleopopulations in relation to diet and vegetation structure in their paleoenvironments. We show a relationship between diet and body size in Equus: very large-sized species tend to have more browse-dominated diets than small and medium-sized species, and paleovegetation proxies indicate on average more open and grass-rich paleoenvironments for small-sized, grazing species of Equus. When more than one species of Equus co-occur sympatrically, the larger species tend to be less abundant and have more browse-dominated diets than the smaller species. We suggest that body size variation in Pleistocene Equus was driven by a combined effect of resource quality and availability, partitioning of habitats and resources between species, and the effect of environmental openness and group size on the body size of individuals.Peer reviewe

Frequency and Clinical Review of the Aberrant Obturator Artery: A Cadaveric Study

The occurrence of an aberrant obturator artery is common in human anatomy. Detailed knowledge of this anatomical variation is important for the outcome of pelvic and groin surgeries requiring appropriate ligation. Familiarity with the occurrence of an aberrant obturator artery is equally important for instructors teaching pelvic anatomy to students. Case studies highlighting this vascular variation provide anatomical instructors and surgeons with accurate information on how to identify such variants and their prevalence. Seven out of eighteen individuals studied (38.9%) exhibited an aberrant obturator artery, with two of those individuals presenting with bilateral aberrant obturator arteries (11.1%). Six of these individuals had an aberrant obturator artery that originated from the deep inferior epigastric artery (33.3%). One individual had an aberrant obturator artery that originated directly from the external iliac artery (5.6%)

PHYLOGENETIC SIGNATURES IN THE JUVENILE SKULLS AND CHEEK TEETH OF PLEISTOCENE <em>PROBOSCIDIPPARION SINENSE</em>, CHINA

We describe and compare three partial skulls of Chinese juvenile Proboscidipparion sinense from the Nihewanian of China. Study of the facial morphology, especially the nasal aperture, as well as cheek tooth morphology and metric data, including length versus width of the maxillary cheek teeth of dP2, 3 and 4, support the conclusion that these skulls are referable to Proboscidipparion sinense. We reaffirm that Proboscidipparion sinense is a member of the “Sivalhippus” Complex that includes the following superspecific clades: Sivalhippus, Eurygnathohippus, Plesiohipparion and Proboscidipparion.  Recent studies by Bernor and Sun (2015) suggest that Proboscidipparion is particularly closely related to Chinese Plesiohipparion, and more distantly related to Eurygnathohippus (exclusively Africa) and Sivalhippus (mostly South Asia

Anatomy, Thorax, Pericardiacophrenic Vessels

The pericardiacophrenic artery and vein make up, with the phrenic nerve, the pericardiacophrenic neurovascular bundle. The vessels pass through the superior thoracic aperture into the superior mediastinum and course along the pathway of the phrenic nerve anterior to the lung roots. The vessels are located between the fibrous pericardium and the parietal pleura in the middle mediastinum and extend inferiorly onto the dome of the diaphragm. The pericardiacophrenic artery supplies blood to the pericardium, diaphragm, and phrenic nerve. While the pericardiacophrenic arteries supply blood to these various tissues, they are also a non-coronary arterial collateral blood supply to the heart. Their most important role clinically is to supply the phrenic nerve with blood when harvesting or surgically anastomosing the internal thoracic artery, as in CABG procedures, preserving blood flow in the pericardiacophrenic artery is important to prevent any ischemic damage to the phrenic nerve. The pericardiacophrenic veins are variable tributaries of the right and left brachiocephalic veins (also formerly known as the innominate veins) or internal thoracic veins. The pericardiacophrenic veins are a minor portocaval anastomosis connecting splenic vein and superior vena cava and can become engorged in portal hypertension. Imaging the pericardiacophrenic veins (or arteries) is a reliable aid in clinical procedures that require locating the phrenic nerve

Duplicated Inferior Vena Cava in a 69-Year-Old White Female Donor

While relatively uncommon, a duplication of the inferior vena cava is moderately well-discussed in the literature. This anatomical variation was noted in a 69-year-old white female donor. This variation is typically asymptomatic; however, it can be associated with complications, such as confusion with a mediastinal mass, increased risk for thromboembolism, and hemorrhage during surgery. It is also associated with a handful of comorbidities, including, but not limited to, congenital renal anomalies such as horseshoe kidney or fused crossed kidney. Research supports that the variation of a duplicated IVC (DIVC) can be due to a failure of the left supracardinal vein to regress during embryonic development

Chronic Atherothrombosis in a Sub-Massive Infrarenal Abdominal Aortic Aneurysm in a 91-Year-Old White Male Donor

Screening for abdominal aortic aneurysms became the standard of care in 2005, yet screening procedures continue to be underutilized. While improvements in mortality rates have been noted over the past 15 years, continued patient mortality from ruptured abdominal aortic aneurysms suggests a need for further research, regarding the effectiveness of the current screening process. Abdominal aortic aneurysms can progress silently, and the risk of rupture increases significantly with increase in diameter. We report a large, untreated infrarenal abdominal aortic aneurysm of 17 cm in length and 8 cm in diameter, showing the chronic atherothrombosis discovered in a 91 year-old white male cadaveric donor. A literature review was conducted to elucidate current understanding of the pathology, risk factors, screening recommendations, and treatment options available for abdominal aortic aneurysms