Radiological Study of Atlas Arch Defects with Meta-Analysis and a Proposed New Classification

This study consists of a retrospective cohort study, a systematic review, and a meta-analysis which were separately conducted. This study aimed to investigate the prevalence of atlas arch defects, generate an evidence-based synthesis, and propose a common classification system for the anterior and combined atlas arch defects. Atlas arch defects are well-corticated gaps in the anterior or posterior arch of the atlas. When both arches are involved, it is known as a combined arch defect. Awareness of these defects is essential for avoiding complications during surgical procedures on the upper spine. The prevalence of arch defects was investigated in an open-access OPC-Radiomics (Radiomic Biomarkers in Oropharyngeal Carcinoma) dataset comprising 606 head and neck computed tomography scans from oropharyngeal cancer patients. A systematic review and meta-analysis were performed to generate prevalence estimates of atlas arch defects and propose a classification system for the anterior and combined atlas arch defects. The posterior arch defect was found in 20 patients (3.3%) out of the 606 patients investigated. The anterior arch defect was not observed in any patient, while a combined arch defect was observed in one patient (0.2%). A meta-analysis of 13,539 participants from 14 studies, including the present study, yielded a pooled-posterior arch defect prevalence of 2.07% (95% confidence interval [CI], 1.22%–2.92%). The prevalences of anterior and combined arch defects were 0.00% (95% CI, 0.00%–0.10%) and 0.14% (95% CI, 0.04%–0.25%), respectively. The anterior and combined arch defects were classified into five subtypes based on their morphology and frequency. The present study showed that atlas arch defects were present in approximately 2% of the general population. For future studies, larger sample sizes should be used for studying arch defects to avoid the small-study effect and to predict the prevalence accurately.

Concomitant variations of the tibialis anterior, and extensor hallucis longus, and extensor hallucis brevis muscles / 대한해부학회지

Tibialis anterior (TA) muscle originates from the lateral surface of tibia and its tendon attaches to the medial cuneiform and base of the first metatarsal. The TA muscle is responsible for both dorsiflexion and inversion of the foot. We present a case of bilateral TA muscle variations that diverge slightly from the current classification systems of this muscle.Recognizing variations such as these may be important for anatomists, surgeons, podiatrists, and physicians. Following routine dissection, an accessory tendon of the TA muscle was found on both sides. Accessory tendons of the extensor hallucis longus and extensor hallucis brevis joined to form a common tendon on both sides. We believe that this unique case will help further the classification systems for the tendons of the TA and also be informative for clinical anatomists as well as physicians treating patients with pathology in this region.

The clinical anatomy of the accessory submandibular gland: a comprehensive review / 대한해부학회지

An accessory submandibular gland is a rare variation. As such, there is limited literature regarding the embryology, anatomy, variations, clinical imaging, and pathology of the accessory submandibular gland. In this article, we review the existing literature on the accessory submandibular gland from clinical and anatomical perspectives. The goal of this review is to provide comprehensive knowledge of this variation which can be useful for oral and maxillofacial/head and neck surgeons, radiologists, and anatomists. Within this review, the embryologic origin as well as the anatomy of the accessory submandibular gland is detailed. Several imaging modalities which can be used to visualize the accessory submandibular gland are outlined as well as its variations. Lastly, this review investigates several reported clinical considerations regarding the accessory submandibular gland including sialoliths, Wharton’s duct obstruction, and pleomorphic adenoma.

Pectorobrachioepicondylaris musculoaponeurotic band: case description with evidence of median nerve compression / 대한해부학회지

Upper limb muscle variations can be encountered on imaging or at surgery. We report an unusual muscle and band found during routine dissection of the arm in a cadaver. This case is described and salient literature reviewed. A band was found that traveled from the insertion of the pectoralis major tendon distally and obliquely toward the medial intermuscular septum and medical epicondyle. Fibers of the brachialis were found to interdigitate into the band. A tunnel was formed that carried the median nerve and brachial vessels. Evidence of median nerve compression was observed. We considered this an example of a pectorobrachioepicondylaris muscle. However, some can lead to clinical presentations. Although the significance of the case reported herein is not certain, signs of median nerve compression were identified. We believe that the term pectorobrachioepicondylaris bests describes the muscle reported herein and that our case represents a previously unreported variant of this muscle.

The first report of the buckled thyroid cartilage in a human cadaver / 대한해부학회지

We present the first case of buckled thyroid cartilage identified in a human cadaver. This rare anatomical variant, in patients, often produces dysphonia and is a potential source for diagnostic confusion. In the cadaveric case described, the laryngeal prominence is deviated to the left without deviation of the internal structures of the larynx, such as vocal folds and vocalis muscles. The medical history of the patient is not known. Finally, a review of current literature on the buckled thyroid cartilage is presented. Such a case represents a rare opportunity to visualize this deformity via anatomical dissection.

The sphenopalatine vein: anatomical study of a rarely described structure / 대한해부학회지

Although in counterpart, the sphenopalatine artery (SPA), has been well described in the medical literature, the sphenopalatine vein (SPV) has received scant attention. Therefore, the present anatomical study was performed. Additionally, we discuss the variations, embryology, and clinical significance of the SPV. Adult cadaveric specimens underwent dissection of the SPV. In addition, some specimens were submitted for histological analysis of this structure. The SPV was found to drain from the sphenoidal sinus and nasal septum. Small tributaries traveled through the nasal septum with the posterior septal branches of the SPA and nasopalatine nerve. The SPA and SPV were found to travel through the sphenopalatine foramen and another tributary was found to perforate the medial plate of the pterygoid process and to connect to the pterygoid venous plexus which traveled lateral to the medial plate of the pterygoid process. The vein traveled through the posterior part of the lateral wall of the nasal cavity with the posterior lateral nasal branches of the SPA and the lateral superior posterior nasal branches of the maxillary nerve. To our knowledge, this is the first anatomical study on the SPV in humans. Data on the SPV provides an improved anatomical understanding of the vascular network of the nasal cavity. Developing a more complete picture of the nasal cavity and its venous supply might help surgeons and clinicians better manage clinical entities such as posterior epistaxis, cavernous sinus infections, and perform endoscopic surgery with fewer complications.

An unusual arrangement between the highest denticulate ligament and posterior inferior cerebellar artery / 대한해부학회지

The posterior inferior cerebellar artery (PICA) is often involved in pathologies of the posterior cranial fossa. Therefore, a good understanding of the vessel’s normal and variant courses is important to the neurosurgeon or neurointerventionalist. During the routine microdissection of the craniocervical junction, an unusual arrangement between the highest denticulate ligament and PICA was observed. On the right side, the PICA was given rise to by the V4 segment of the vertebral artery 9 mm after the artery entered the dura mater of the posterior cranial fossa. The artery made an acute turn around the lateral edge of the highest denticulate ligament to then recur 180 degrees and travel medially toward the brainstem. Invasive procedures that target the PICA should be aware of the variant as described herein.

The notch of the mandible: what do different fields call it? / 대한해부학회지

The bony notch on the inferior border of the mandible, anterior to the attachment of the masseter muscle, where the facial vessels commonly pass, has been called different names in the literature, e.g., premasseteric notch, antegonial notch, and notch for the facial vessels. Interestingly, various disciplines have leaned toward different names for this notch. Therefore, to aid in consistent communication among professionals, the present study aimed to analyze usage of these varied terms and make recommendations for the best terminology. Based on the adjacent anatomical structures used to name this notch, three groups were analyzed in this study, a group using masseter in the term, a group using gonion in the term, and a group using facial vessels in the term. A literature search found that the group using gonion in the term was found most in the literature.The orthodontics field used gonion in the term the most (29.0%: 31/107) followed by the oral and maxillofacial surgery field (14.0%: 15/107), the plastic surgery field (4.7%: 5/107), and the anatomy field (3.7%: 4/107). The dental field used gonion in this term the most (43.9%: 47/107) and the medical field used facial vessels in the term the most (33.3%: 6/18). Based on these results, the use of gonial terms for this notch seems to be preferred.

Innervation of pineal gland by the nervus conarii: a review of this almost forgotten structure / 대한해부학회지

The nervus conarii provides sympathetic nerve innervation to the pineal gland, which is thought to be the primary type of stimulus to this gland. This underreported nerve has been mostly studied in animals. One function of the nervus conarii may be to activate pinealocytes to produce melatonin. Others have also found substance P and calcitonin gene-related peptide from the nervus conarii ending in the pineal gland. The following paper reviews the extant medical literature on the nervus conarii including its anatomy and potential function.

The laryngopharyngeal nerve: a comprehensive review / 대한해부학회지

The laryngopharyngeal nerve has received much less attention that the other contributions to the pharyngeal plexus i.e., glossopharyngeal and vagus nerves. Often, in descriptions and depictions, the nerve is simply labeled as the sympathetic contribution to the pharyngeal plexus. As there is such scant information available regarding this nerve, the present review was performed. Very little is found in the extant medical literature regarding the laryngopharyngeal nerve. However, based on available data, the nerve is a consistent contributory to the pharyngeal plexus and serves other adjacent areas e.g., carotid body. Therefore, a better understanding of this structure’s anatomy is important for those who operate in this area. Further studies are necessary to better elucidate the true function of the laryngopharyngeal nerve.

Duplication of the ovarian vein: comprehensive review and case illustration / 대한해부학회지

Variations of the ovarian veins can impact imaging diagnosis, surgical procedures of the region, and can be related to clinical findings such as compression of the ureter. Therefore, a good working knowledge of such variants is important to the clinician who interprets imaging of the posterior abdominopelvic region of women and surgeons who operate in this region. Herein, we present a comprehensive review of duplicated ovarian veins and provide a case illustration.

Three ipsilateral paracondylar processes with other skull base variations: case report / 대한해부학회지

Variations of the skull base can affect surgical approaches and must be considered when viewing and interpreting radiological imaging. Here, we report a unique collection of bony anatomical variations found on a single adult skull. Three bony excrescences from the occipital bone were identified in the paracondylar region. The smallest of these processes was 7 mm long and was just medial to the mastoid process of the temporal bone and posterior to the styloid process. One bony process was attached to the occipital condyle and was 12 mm in length. The longest of these processes was 17 mm long and arose from the jugular process of the occipital bone. Paracondylar processes can be symptomatic. Knowledge of the bony variations at the skull base is important to those who operate in this region or review and interpret radiological imaging.

Morphology of the groove of the inferior petrosal sinus: application to better understanding variations and surgery of the skull base / 대한해부학회지

Although adequate venous drainage from the cranium is imperative for maintaining normal intracranial pressure, the bony anatomy surrounding the inferior petrosal sinus and the potential for a compressive canal or tunnel has, to our knowledge, not been previously investigated. One hundred adult human skulls (200 sides) were observed and documented for the presence or absence of an inferior petrosal groove or canal. Measurements were made and a classification developed to help better understand their anatomy and discuss it in future reports. We identified an inferior petrosal sinus groove (IPSG) in the majority of specimens. The IPSG began anteriorly where the apex of the petrous part of the temporal bone articulated with the sphenoid part of the clivus, traveled posteriorly, in a slight medial to lateral course, primarily just medial to the petro-occipital fissure, and ended at the anteromedial aspect of the jugular foramen. When the IPSGs were grouped into five types. In type I specimens, no IPSG was identified (10.0%), in type II specimens, a partial IPSG was identified (6.5%), in type III specimens, a complete IPSG (80.0%) was identified, in type IV specimens, a partial IPS tunnel was identified (2.5%), and in type V specimens, a complete tunnel (1.0%) was identified. An improved knowledge of the bony pathways that the intracranial dural venous sinuses take as they exit the cranium is clinically useful. Radiological interpretation of such bony landmarks might improve patient diagnoses and surgically, such anatomy could decrease patient morbidity during approaches to the posterior cranial fossa.

Discovery of a trans-sellar vascular supply for the pituitary gland / 대한해부학회지

The vasculature of the pituitary gland is discussed briefly and the details of an anatomical discovery of the vessels supplying the pituitary gland provided. Twenty latex injected cadaveric heads were dissected. Any vessels that were found to penetrate the sella turcica and travel to the pituitary gland were documented and measured. Additionally, 25 adult skulls were evaluated for the presence, size, and sites of bony foramina in the floor of sella turcica. Trans-sellar vessels were identified in 65% of specimens. There was a mean of 1.5 vessels per specimen consisting usually of a mixture of veins and arteries. The mean diameter of these vessels was 0.3 mm and the mean length from the sella turcica to the pituitary gland was 2.3 mm. These vessels were concentrated in the most concave part of the sella turcica. In bony specimens, the mean number of transsellar foramina was four. The diameter of these foramina ranged from 0.3 to 0.6 mm in size. The trans-sellar foramina were concentrated near the center part of the sella turcica and had no regular pattern. The pituitary gland receives at least some blood supply and drainage via vessels traveling along the septum of the sphenoidal sinuses and through the sella turcica.Knowledge of such vessels might lead to a better understanding of the vascular supply and drainage of the pituitary gland and would be useful during skull base approaches such as trans-nasal approaches to the pituitary gland.

The function of the tensor tympani muscle: a comprehensive review of the literature / 대한해부학회지

The tensor tympani muscle is structurally important in the middle ear, specifically through its involvement in the impedance of sound in response to intense auditory and non-auditory stimuli. Despite numerous studies, its true function has been debated for many years; questions still remain about its role in auditory and non-auditory reflexes and in sound damping. Some studies suggest that the tensor tympani muscle contracts as a result of non-auditory stimulation such as facial or head movements; others suggest that it contracts due to input from the cochlear nucleus, therefore by way of auditory stimulation. Whatever the cause, contraction of the tensor tympani muscle results in low frequency mixed hearing loss, either to protect the inner ear from loud sounds or to desensitize the ear to self-generated sounds. A review of these studies indicated that the tensor tympani muscle has a wide range of functions, yet the mechanisms of some of them have not been clearly demonstrated. One major question is whether the tensor tympani muscle contributes to sound damping; and if it does, what specific role it serves. The primary purpose of this review article is to explore the functions of the tensor tympani muscle in light of recent research advances.

Variant muscle fibers connecting the orbicularis oculi to the orbicularis oris: case report / 대한해부학회지

The orbicularis oculi (OOc) is a sphincteric muscle of the eyelids, whereas contraction of the orbicularis oris (OOr), another sphincteric muscle, causes narrowing of the lips. Facial muscle fibers normally blend with adjacent muscles. However, muscle fibers connecting the various facial muscles that have different actions and that are located at distant sites, such as the OOc and the OOr have been rarely reported. Herein, we report a rare case of connecting fibers between the inferior margin of the OOc and the OOr. These connecting fibers were blended with the OOr between the inserting fibers of the levator labii superioris and levator anguli oris. Contraction of such variant muscles might affect typical facial expressions.

Review of the external carotid plexus: anatomy, function, and clinical manifestations / 대한해부학회지

The external carotid plexus is a combination of postganglionic sympathetic fibers derived from the superior cervical ganglion. This plexus travels along the external carotid artery and continues onto the artery’s branches. The external carotid plexus plays an important role in innervating the mid and lower face. Therefore, implications to the plexus may result in facial abnormalities. Herein, we review the anatomy, function, and review its clinical applications.

Chiari 1.5 malformation, accessory odontoid synchondrosis, and ventral compression:case report / 대한해부학회지

The pathogenesis of Chiari 1 malformations has been explained in several different ways, but extensive evidence suggests a relationship between loss of volume within the posterior cranial fossa and Chiari 1 presentations. It is important to be able to differentiate Chiari 1.5 from Chiari 1 malformations as they have similar clinical presentations, but the latter have progressed further and are characterized by caudal herniations of the brain stem through the foramen magnum. Despite the similarities of presentation, Chiari 1.5 malformations have greater rates of complications following posterior decompression surgeries, which are typically performed to relieve ventral compression. An improved understanding of the odontoid synchondroses could lead to better understanding of Chiari malformations and lead to improved treatment of patients with these presentations. Here we present a rare case of an accessory odontoid synchondrosis in a patient with a Chiari 1.5 malformation and ventral compression.

Duplicated transverse cervical nerve and external jugular vein / 대한해부학회지

The transverse cervical nerve arises from anterior rami of the second and third cervical spinal nerves via the cervical plexus. We present a case of a left duplicated transverse cervical nerve with a duplicated external jugular vein in a 72-year-old female cadver. The transverse cervical nerve bifurcated into two branches, i.e., superficial and deep branches, lateral to the sternocleidomastoid muscle. The superficial branch ran lateral to the duplicated external jugular vein and gave a cutaneous branch to the area below the great auricular nerve and cutaneous branches to the skin of the neck. The deep branch ran medial to the duplicated external jugular vein, joined the anterior branch of the superficial transverse cervical nerve and cervical branch of the facial nerve, and terminated into the skin. This case adds to the growing data on individual variability that should be considered when operating on the anterolateral neck.

Rare anastomosis between the ascending pharyngeal and vertebral arteries via the hypoglossal canal: A cadaveric case report / 대한해부학회지

We present a rare case of external carotid artery-vertebral artery anastomosis via the ascending pharyngeal artery, diagnosed upon cadaveric dissection. The ascending pharyngeal artery gave rise to a branch to the hypoglossal canal, which is a variation of a true persistent fetal hypoglossal artery. Knowledge of persistent carotid-vertebrobasilar anastomoses is important as these fetal vessels can contribute significantly to the posterior cerebral circulation. Only 10 cases of external carotid artery-vertebrobasilar artery anastomoses have been reported to our knowledge, and our case presents the first cadaveric dissection of this rare variation.