Transcription factor support for the dual embryological origin of the sternocleidomastoid and trapezius muscles.

The embryological origin of the trapezius and sternocleidomastoid muscles has been debated for over a century. To shed light on this issue, the present anatomical study was performed. Five fresh frozen human cadavers, three males and two females, were used for this study. Samples from each specimen's trapezius and sternocleidomastoid were fixed in 10% formalin and placed in paraffin blocks. As Paired like homeodomain 2 (Pitx2) and T-box factor 1(Tbx1) have been implicated in the region and muscle type regulation, we performed Tbx1 and Pitx2 Immunohistochemistry (IHC) on these muscle tissue samples to identify the origin of the trapezius and sternocleidomastoid muscles. We have used the latest version of QuPath, v0.4.3, software to quantify the Tbx and Pitx2 staining. For the sternocleidomastoid muscle, for evaluated samples, the average amount of positively stained Tbx1 and Pitx2 was 25% (range 16%-30%) and 18% (range 12%-23%), respectively. For the trapezius muscles, for evaluated samples, the average amount of positively stained Tbx1 and Pitx2 parts of the samples was 17% (range 15%-20%) and 15% (14%-17%), respectively. Our anatomical findings suggest dual origins of both the trapezius and sternocleidomastoid muscles. Additionally, as neither Pitx2 nor Tbx1 made up all the staining observed for each muscle, other contributions to these structures are likely. Future studies with larger samples are now necessary to confirm these findings.

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

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.

C6 and not C5 nerve fibers more commonly contribute most to deltoid muscle innervation: anatomical study with application to better diagnosing cervical nerve injuries.

Most anatomical textbooks list both the C5 and C6 spinal nerves as contributing to the deltoid muscle's innervation via the axillary nerve. To our knowledge, no previous study has detailed the exact spinal nerve components of the axillary nerve terminating in the deltoid via cadaveric dissection. Twenty formalin-fixed cadavers (40 sides) underwent dissection of the brachial plexus. The fascicles making up the axillary nerve branch that specifically terminated in the deltoid muscle were traced proximally. The axillary nerve branch to the deltoid muscle was most commonly (70%) made up of three spinal nerve segments and less commonly (30%) by two spinal nerve segments. For all axillary nerve branches to the deltoid muscle, C4 spinal nerves contributed 0-5%, C5 spinal nerves contributed 1-80%, C6 spinal nerve contributed 15-99%, C7 spinal nerves contributed 0-30%, and C8 and T1 spinal nerves were not found to contribute any fibers to any deltoid muscle branches. The nerve to the deltoid muscle was contributed to equally by C5 and C6 nerve fibers on 10% of sides. On 16% of sides, C5 contributed the most nerve fibers to this muscle. On 35% of sides, C6 contributed the majority fibers found in the axillary nerve branches to the deltoid. Based on our anatomical study, C6 is more often than not the main level of innervation. C5 was never the sole component of the axillary nerve branches to the deltoid muscle. Such anatomical data will now need to be reconciled with clinical studies.

A comprehensive review of the "supracondylar process" with translation of Adachi.

The supracondylar process is a nonpathological projection from the distal humerus that in some patients, can result in compression of regional neurovascular structures, for example, median nerve. Since the first description of the supracondylar process in 1818, it has also been a focus of anthropological study because of its possible relevance to human origins and relationships to other species. Although its overall incidence is low, it is more common in races of European descent. It is particularly interesting for anatomists and anthropologists, but knowledge of its anatomical relationships and effect on pathological processes helps in the diagnosis and treatment of supracondylar process syndrome. One of the most detailed descriptions of this variant process stems from the work of Buntaro Adachi. Herein, a translation of his findings is provided and a review of the supracondylar process and its potential pathological presentations presented.

The pharyngeal plexus: an anatomical review for better understanding postoperative dysphagia.

The pharyngeal plexus is an essential anatomical structure, but the contributions from the glossopharyngeal and vagus nerves and the superior cervical ganglion that give rise to the pharyngeal plexus are not fully understood. The pharyngeal plexus is likely to be encountered during various anterior cervical surgical procedures of the neck such as anterior cervical discectomy and fusion. Therefore, a detailed understanding of its anatomy is essential for the surgeon who operates in and around this region. Although the pharyngeal plexus is an anatomical structure that is widely mentioned in literature and anatomy books, detailed descriptions of its structural nuances are scarce; therefore, we provide a comprehensive review that encompasses all the available data from this critical structure. We conducted a narrative review of the current literature using databases like PubMed, Embase, Ovid, and Cochrane. Information was gathered regarding the pharyngeal plexus to improve our understanding of its anatomy to elucidate its involvement in postoperative spine surgery complications such as dysphagia. The neural contributions of the cranial nerves IX, X, and superior sympathetic ganglion intertwine to form the pharyngeal plexus that can be injured during ACDF procedures. Factors like surgical retraction time, postoperative hematoma, surgical hardware materials, and profiles and smoking are related to postoperative dysphagia onset. Thorough anatomical knowledge and lateral approaches to ACDF are the best preventing measures.

The proximal humeral attachment of the lateral head of the triceps brachii: a cadaveric study and potential site for radial nerve compression.

BACKGROUND: Knowledge of potential compression sites of peripheral nerves is important to the clinician and surgeon alike. One anatomical location for potential compression of the radial nerve, which is rarely mentioned in the literature, is at the proximal humeral attachment of the lateral head of the triceps brachii at the level of the proximal spiral groove. As no anatomical studies have been devoted to this band, the present study was conducted. METHODS: Ten adult fresh-frozen cadavers were dissected and the lateral head's attachment onto the posterior humerus evaluated for a band. This anatomy and its relation to the radial nerve during range of motion of the elbow and forearm were evaluated. RESULTS: A band was found on 15 of 20 arms. On five sides, the band was comprised of grossly muscle fibers of the lateral head of the triceps brachii and was not tendinous. The bands were crescent-shaped, straight, and duplicated on nine, five, and one arm, respectively. The length of the bands ranged from 1.1 to 2.2 cm (mean 1.54 cm). The width of the bands ranged from 0.5 to 1.1 cm (mean 0.8 cm). With elbow extension and the forearm in neutral, all bands were lax. With elbow extension and the forearm supinated, the bands became tauter less the muscular bands. In elbow extension and with the forearm in supination, the bands became most taut less the muscular bands. CONCLUSIONS: The presence of a fibrous band extending from the lateral head of the triceps brachii is common and should be among the differential diagnoses of anatomical sites for potential proximal radial nerve compression when other more common locations are ruled out.

Ulnar nerve subluxation and dislocation: a review of the literature.

The pathogenesis of ulnar nerve subluxation and dislocation is widely debated. Upon elbow flexion, the ulnar nerve slips out of the groove for the ulnar nerve, relocates medial or anterior to the medial epicondyle, and returns to its correct anatomical position upon extension. This chronic condition can cause neuritis or neuropathy; however, it has also been suggested that it protects against neuropathy by reducing tension along the nerve. This article reviews the extant literature with the aim of bringing knowledge of the topic into perspective and standardizing terminology.

Lower cranial nerve syndromes: a review.

The purpose of this paper is to provide a comprehensive review encompassing the syndromes associated with the lower cranial nerves (LCNs). We will discuss the anatomy of some of these syndromes and the historical contributors after whom they were named. The LCNs can be affected individually or in combination, since the cranial nerves at this level share their courses through the jugular foramen and hypoglossal canal and the extracranial spaces. Numerous alterations affecting them have been described in the literature, but much remains to be discovered on this topic. This paper will highlight some of the subtle differences among these syndromes. Symptoms and signs that have localization value for LCN lesions include impaired speech, deglutition, sensory functions, alterations in taste, autonomic dysfunction, neuralgic pain, dysphagia, head or neck pain, cardiac or gastrointestinal compromise, and weakness of the tongue, trapezius, or sternocleidomastoid muscles. To assess the manifestations of LCN lesions correctly, precise knowledge of the anatomy and physiology of the area is required. Treatments currently used for these conditions will also be addressed here. Effective treatments are available in several such cases, but a precondition for complete recovery is a correct and swift diagnosis.

Sacral fractures: An updated and comprehensive review.

Sacral fractures are often underdiagnosed but are relatively frequent in the setting of pelvic ring injury. Causes include traumatic insults and osteoporosis. Sacral fractures have become more frequent owing to the growth of the elderly population worldwide as osteoporosis is an age-related disease. Misdiagnosed and neglected sacral fractures can result in chronic back pain, spine deformity, and instability. Unfortunately, the wide range of classification systems hinders adequate communication among clinicians. Therefore, a complete understanding of the pathology, and communication within the interdisciplinary team, are necessary to ensure adequate treatment and satisfactory clinical outcomes. The aim of this manuscript is to present the current knowledge available regarding classification systems, clinical assessment, decision-making factors, and current treatment options.

The falciform ligament: Anatomical study with microsurgical implications.

OBJECTIVES: The current study aims to increase awareness of the falciform ligament and its anatomical and surgical relationships, for the benefit of the neurosurgeon. PATINENTS AND METHODS: Twenty-four sides from twelve Caucasian cadaveric heads (all fresh-frozen) were used in this study. The length and thickness of the falciform ligament were recorded. The relationship of the falciform ligament to the optic nerve was also observed and documented. Finally, the force needed to avulse the falciform ligament was recorded. RESULTS: In all specimens, the ligament was identified as a continuation of the outer dural layer, forming a roof at the entrance of the optic canal. The mean medial-to-lateral length, anteroposterior length, and thickness of the falciform ligament were 7.97 mm, 2.12 mm, and 0.26 mm, respectively. The mean distance from the medial attachment of the ligament to the midline was 5.54 mm. For the undersurface of the falciform ligament, the optic nerve occupied the middle third in 50.0 %, the lateral third in 44.4 %, and the medial third in 5.6 % of sides. The mean optic nerve diameter at the entrance of the optic canal was 4.20 mm. The mean failure force was 2.47 N. CONCLUSION: The anatomical measurements and relationships provided in this description of the falciform ligament serve as a tool for surgery selection and planning, as well as an aid to improving microsurgical techniques, with the final goal being better patient outcomes.

Choroidal fissure and choroidal fissure cysts: a comprehensive review.

In this paper, the authors discuss the embryology and anatomy of the choroidal fissure, as well as the pathophysiology and treatment of cerebrospinal fluid cysts of this structure. Understanding its anatomical relations to nearby structures plays an essential role during brain surgeries. With the advancement and availability of imaging techniques, lesions of the choroidal fissure are often found incidentally. Patients are usually asymptomatic or exhibit symptoms that do not correlate with anatomical location or do not require surgical treatment. The choroidal fissure is a key landmark used during brain surgery. Therefore, a comprehensive understanding of it and nearby anatomical structures is essential. Choroidal fissure cysts can be found incidentally, and well-known key features will allow one to differentiate them from other lesions. Surgical treatment should be reserved for symptomatic patients while asymptomatic patients should be monitored.

Caudal Regression Syndrome-A Review Focusing on Genetic Associations.

Caudal regression syndrome (CRS) represents a spectrum of clinical phenotypes with varying degrees of malformation of the lower body with involvement of structures deriving from all 3 layers of the trilaminar embryo. We review areas of active investigation in the diagnosis, etiology, epidemiology, and treatment of the disease with a focus on underlying genetics. CRS pathobiology is complex and multifactorial with a significant contribution from environmental factors as evidenced in twin studies. Contemporary genomic and genetic investigations in both human primary tissue and murine in vitro and in vivo models implicate various genes associated with caudal differentiation and neural cell migration in embryogenesis. A large number of identified targets center around the metabolic regulation of retinoic acid and its derivatives. Dysregulation of retinoic acid homeostasis has been associated with abnormal embryonic cell migration, differentiation, and organogenesis with resulting malformations and agenesis in both a laboratory and a clinical setting. There appears to be a significant overlap in potential genetic targets with CRS and other developmental syndromes with similar presentations, such as VACTERL (vertebral defects, anal atresia, cardiac defects, tracheo-esophageal fistula, renal anomalies, and limb abnormalities) association. CRS represents a spectrum of caudal developmental abnormalities with treatment options limited to mild and moderate expressions of disease. Continued research is necessary to further clarify mechanisms of disease pathobiology and complex polygenetic and environmental interaction. Despite this, progress has been made in identifying genetic targets and downstream effectors contributing to preclinical and clinical progression.

Arterial Supply of the Thalamus: A Comprehensive Review.

The thalamus is a deep cerebral structure that is crucial for proper neurological functioning as it transmits signals from nearly all pathways in the body. Insult to the thalamus can, therefore, result in complex syndromes involving sensation, cognition, executive function, fine motor control, emotion, and arousal, to name a few. Specific territories in the thalamus that are supplied by deep cerebral arteries have been shown to correlate with clinical symptoms. The aim of this review is to enhance our understanding of the arterial anatomy of the thalamus and the complications that can arise from lesions to it by considering the functions of known thalamic nuclei supplied by each vascular territory.

A Review of the History, Anatomy, and Development of the C1 Spinal Nerve.

The C1 spinal nerve is a fascinating anatomic structure owing to its wide range of variations. Throughout history, understanding of the cranial and spinal nerves has probably influenced the current conception of this nerve among anatomists. Located at the craniocervical junction, the C1 spinal nerve contributes to the motor innervation of deep cervical muscles through the cervical (anterior) and Cruveilhier's (posterior) plexuses. Sensory functions of this nerve are more enigmatic; despite investigations into its dorsal rootlets, a dorsal root ganglion, and the relationships between this nerve and adjacent cranial and spinal nerves, there is still no consensus regarding its true anatomy. In this article, we review the available literature and discuss some of the developmental models that could potentially explain the wide range of variations and functions of the C1 nerve.

Intervention for A randomized trial of unruptured brain arteriovenous malformations (ARUBA) - Eligible patients: An evidence-based review.

While intervention for ruptured arteriovenous malformations (AVMs) of the brain is typically warranted, the management of unruptured AVMs remains controversial. Despite numerous retrospective studies, only one randomized controlled trial has been conducted, comparing the role of medical management alone to medical management plus surgical and/or radiosurgical intervention in patients with unruptured AVMs: A Randomized Trial of Unruptured Brain Arteriovenous Malformations (ARUBA). To great controversy, ARUBA concluded that medical management alone was superior to intervention for unruptured AVMs, which was subsequently challenged by various single-institution and multi-center studies analyzing outcomes of ARUBA-eligible patients. This review summarizes studies returned from a PubMed database search querying, 'ARUBA,' 'ARUBA-eligible,' 'surgery unruptured AVM,' and "radiosurgery unruptured AVM". The rates of the primary endpoint of symptomatic stroke or death were low among the analyzed studies (0-12.2%, mean 8.0%) and similar to the medically managed arm of ARUBA (10.1%). Likewise, the percentage of patients with impaired functional outcomes (modified Rankin score ≥2) in the reviewed studies was low (5.9%-13.1%; mean: 9.9%) and comparable to the 14.0% observed in the medically management arm of ARUBA. The key findings of ARUBA and subsequent work in its aftermath are overviewed and analyzed for the role of surgery and/or radiosurgery in patients with unruptured AVMs.

Treatment of small ruptured intracranial aneurysms: comparison of surgical and endovascular options.

BACKGROUND: Small intracranial aneurysms pose significant challenges to endovascular therapy. Surgical clipping is considered by many to be the preferred treatment for these lesions. We present the results of the first study comparing the 2 treatment modalities in small ruptured aneurysms. METHODS AND RESULTS: Between 2004 and 2011, 151 patients with small ruptured aneurysms (≤3 mm) were treated in our institution: 91 (60.3%) with endovascular therapy and 60 (39.7%) with surgical clipping. The surgical and endovascular groups were generally comparable with regard to baseline demographics, with the exception of larger mean aneurysm size in the endovascular group versus the surgical group (2.8 versus 2.5 mm, respectively; P<0.001) and a higher proportion of posterior circulation aneurysms in the endovascular group. Endovascular treatment failed in 9.9% of patients. Procedure-related complications occurred in 23.3% of surgical patients versus 9.8% of endovascular patients (P=0.01). Only 3.7% of patients undergoing endovascular therapy experienced an intraprocedural aneurysm rupture. There were no procedural deaths or rehemorrhages in either group. The rates of aneurysm recanalization and retreatment after endovascular therapy were 18.2% and 12.7%, respectively. Favorable outcomes (moderate, mild, or no disability) were not statistically different between the endovascular (67.1%) and surgical (56.7%) groups (P=0.3). CONCLUSIONS: Surgical clipping was associated with a higher rate of periprocedural complications, but overall disability outcomes were similar. Endovascular therapy, if technically feasible, might be a preferred option in this setting. Inclusion of patients with small aneurysms in randomized controlled trials seems feasible and will be needed to provide definitive information on the best therapeutic approach. (J Am Heart Assoc. 2012;1:e002865 doi: 10.1161/JAHA.112.002865.).