Untrapped: bilateral hypoplasia of the trapezius muscle / 대한해부학회지

Agenesis or congenital hypoplasia of skeletal muscles occurs infrequently but may occur with specific conditions such as Poland syndrome. The trapezius muscle can vary in the extent of its bony attachments or may have additional slips, however congenital absence or hypoplasia is extremely rare. There are only a few reports of partial or complete absence of the trapezius muscle. Two cases of bilateral absence of the trapezius were both in males and were accompanied by the absence of additional muscle in the pectoral girdle. Herein, we describe a case of a 56-year-old male cadaver with bilateral hypoplasia of the trapezius. The muscle was largely represented by atrophied muscle fibers with an abundance of fibrotic or fatty connective tissue. This subject had very minor hypoplasia of the left pectoralis major muscle, but the remaining muscles of the pectoral girdle were normal. The spinal accessory nerve terminated in the sternocleidomastoid muscle on both sides, failing to reach the trapezius. We interpret these findings to be consistent with a minor variant of Poland syndrome.

Noradrenergic axons hitch hiking along the human abducens nerve / 대한해부학회지

The abducens nerve (AN; cranial nerve VI) exits the brainstem at the inferior pontine sulcus, pierces the dura of the posterior cranial fossa, passes through the cavernous sinus in close contact to the internal carotid artery (ICA) and traverses the superior orbital fissure to reach the orbit to innervate the lateral rectus muscle. At its exit from the brainstem, the AN includes only axons from lower motor neurons in the abducens nucleus. However, as the AN crosses the ICA it receives a number of branches from the internal carotid sympathetic plexus. The arrangement, neurochemical profile and function of these sympathetic axons running along the AN remain unresolved. Herein, we use gross dissection and microscopic study of hematoxylin and eosin-stained sections and sections with tyrosine hydroxylase immunolabeling. Our results suggest the AN receives multiple bundles of unmyelinated axons that use norepinephrine as a neurotransmitter consistent with postganglionic sympathetic axons.

A portal quadrad with triple hepatic arteries / 대한해부학회지

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.

A rare variation of the glossopharyngeal nerve / 대한해부학회지

The glossopharyngeal nerve (CN IX) provides innervation to the parotid gland, carotid body/sinus, mucosa of the middle ear, tongue and oropharynx and the stylopharyngeus muscle. The vagus nerve provides innervation to the remaining skeletal muscle of the pharynx. CN IX contributes to the pharyngeal plexus and normally provides innervation to the mucosa of the oropharynx. Herein, we describe a previously undescribed variation of CN IX. CN IX was observed to enter the pharyngeal wall but instead of forming terminal branches in the tonsillar fossa, CN IX descended along the posterior wall between the mucosa and pharyngeal constrictors to the esophagus. This unusual branch of CN IX gave rise to numerous branches along the pharynx but did not intermingle with laryngeal branches from the vagus nerve. From this dissection, we developed innervation maps of the pharynx and propose a central miswiring mechanism for this unusual variation.

A rare variation of the glossopharyngeal nerve / 대한해부학회지

The glossopharyngeal nerve (CN IX) provides innervation to the parotid gland, carotid body/sinus, mucosa of the middle ear, tongue and oropharynx and the stylopharyngeus muscle. The vagus nerve provides innervation to the remaining skeletal muscle of the pharynx. CN IX contributes to the pharyngeal plexus and normally provides innervation to the mucosa of the oropharynx. Herein, we describe a previously undescribed variation of CN IX. CN IX was observed to enter the pharyngeal wall but instead of forming terminal branches in the tonsillar fossa, CN IX descended along the posterior wall between the mucosa and pharyngeal constrictors to the esophagus. This unusual branch of CN IX gave rise to numerous branches along the pharynx but did not intermingle with laryngeal branches from the vagus nerve. From this dissection, we developed innervation maps of the pharynx and propose a central miswiring mechanism for this unusual variation.