Three-Headed Biceps Brachii Muscle: A Rare Site of Proximal Median Nerve Entrapment.

The biceps brachii muscle is a highly variable muscle in the anterior compartment of the arm, and the most common variants include additional heads or slips. The median nerve courses with the brachial artery in the medial arm near the biceps brachii muscle, crosses the elbow, and enters the forearm deep to the bicipital aponeurosis. While entrapment of the median nerve in the carpal tunnel is one of the most common neuropathies, more proximal entrapments by the bicipital aponeurosis or other variants have been reported. In a 94-year-old embalmed female cadaver received through the Humanity Gift Registry of Pennsylvania, a biceps brachii muscle with an additional slip that arose from the coracoid process was found, which bridged over the median nerve and blended with the investing fascia of the forearm flexors via aponeurosis. Because of the course of this muscular slip in the arm and its relationship to the median nerve, this may be an additional site of proximal entrapment of the median nerve. It is important to consider these rare sites of nerve entrapment when diagnosing patients with median nerve neuropathy.

Pterygoideus proprius muscle: stuck between the greater wing and lateral pterygoid plate.

The muscles of mastication derive from a common embryological source, and the presence of accessory muscles in the infratemporal fossa (ITF) is uncommon. Here, we present findings from postmortem dissection of the ITF revealing a unilaterally present muscle extending from the greater wing of the sphenoid to blend inferiorly with the medial and lateral pterygoid muscles before attaching to the lateral pterygoid plate. This muscle is most consistent with the pterygoideus proprius muscle initially described in 1858. Though the exact embryological origin and function of this muscle remain speculative, these topics are nonetheless worth investigating as it may provide insight regarding the ontogeny of muscles descending from the first pharyngeal arch. Additionally, presence of the pterygoideus proprius muscle may have clinical implications and impact surrounding structures such as the mandibular division of the trigeminal nerve, maxillary artery, pterygoid venous plexus, masticatory muscles, and temporomandibular joint (TMJ).

A portal quadrad with triple hepatic arteries.

The arterial support of the liver is most commonly from the celiac trunk via the proper hepatic artery (PHA). The PHA divides into left and right branches: the right hepatic artery (RHA) supplies the right and caudate lobes while the left hepatic artery (LHA) supplies the left and quadrate lobes. Aberrant hepatic arteries are relatively common, and the most frequent contributors are the superior mesenteric artery and left gastric artery. Herein we present findings from postmortem dissection of an abdominal cavity that revealed a rare combination of reported variations. Specifically, this subject had three extrahepatic arteries - a replaced LHA (rLHA), a PHA, and a replaced RHA (rRHA). The rLHA originated from the left gastric and the rRHA originated from the superior mesenteric artery. Knowledge of these variations is important for surgical and radiological procedures to avoid complications during treatment and improve patient outcomes.