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

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.

Duplication and Fenestration of the Inferior Petrosal Sinus: Cadaveric Study with Application to Imaging, Skull Base Surgery, and Neurointerventional Procedures.

BACKGROUND: Reports of a duplicated or fenestrated inferior petrosal sinus (IPS) are scarce or not found in the literature, respectively. To our knowledge, there are no cadaveric reports of the latter. METHODS: This study used 20 adult cadaveric heads (40 sides). After removal of the brain, the IPS was dissected using a surgical microscope. Specimens with duplication or fenestration of the IPS anywhere along its course were photographed and measured. RESULTS: On 2 (5%) left sides, a fenestration was identified in the IPS. One of these was found to have 2 fenestrations. The mean length and width of the 3 fenestrations were 2.3 mm and 0.95 mm, respectively. The 3 fenestrations were located at the middle to terminal parts of the IPS. On 2 (5%) left sides and 1 (2.5%) right side, the IPS was duplicated over a part of its course. The mean length and width of the duplicated parts of the IPS were 25.9 mm and 3.1 mm, respectively. No statistical significance was found for fenestrations or duplications comparing males versus females, but fenestrations were statistically significant (P < 0.05) for occurring on left sides. CONCLUSIONS: Unfamiliarity with a duplicated or fenestrated IPS could increase risk of iatrogenic injury and misinterpretation of imaging. Further radiological imaging studies are required to substantiate more accurately the mechanisms by which a duplicated or fenestrated IPS affects clinical outcomes. Nonetheless, anatomical awareness of such lesser known variations of the IPS is crucial for promoting safe and effective interventional approaches at the skull base.

Variant Innervation of the Medial Pterygoid Muscle from the Lingual Nerve.

During a routine dissection of the infratemporal fossa and lateral face, a branch of the left lingual nerve was observed entering the medial pterygoid muscle. Normally, the nerve to the medial pterygoid is a direct branch from the mandibular nerve, with no communications with the lingual nerve. There are many reports involving variations of the mandibular nerve; however, few reports describe lingual nerve variations involving the medial pterygoid muscle. Reconstructive surgeries for cosmesis and trauma, tumor excision, and impacted third molar removal may all damage the lingual nerve and might, as seen in the present case, affect the medial pterygoid muscle. Given the presumed rarity of this variation, we discuss the possible embryological origins as well as the surgical conflicts that may arise with this type of variation.

Update on the Biomechanics of the Craniocervical Junction-Part I: Transverse Atlantal Ligament in the Elderly.

STUDY DESIGN: In vitro biomechanical study. OBJECTIVE: The transverse ligament is the strongest ligament of the craniocervical junction and plays a critical role in atlanto-axial stability. The goal of this cadaveric study, and the subsequent study (part II), was to reevaluate the force required for the transverse ligament and alar ligament to fail in a more physiological biomechanical model in elderly specimens. METHODS: Twelve C1-2 specimens were harvested from fresh-frozen Caucasian cadavers with a mean age at death of 81 years (range 68-89 years). Only the transverse ligament was preserved, and the bony C1-2 complex was left intact. The dens was pulled away from the anterior arch of C1 using a strength test machine that applies controlled increasing force. After testing, the axis was split in half to check for hidden pathologies and osteoporosis. The differences in the failure force between sex and age groups (group 1: <80 years, group 2: >80 years) were compared. RESULTS: The mean force required for the transverse ligament to fail was 236.2 ± 66 N (range 132-326 N). All but 2 specimens had significant osteoporotic loss of trabecular bone. No significant differences between sex and age groups were found. CONCLUSIONS: The transverse ligament's failure in elderly specimens occurred at an average force of 236 N, which was lower than that reported in the previous literature. The ligament's failure force in younger patients differs and may be similar to the findings published to date.

The effects of obesity on the human body, part I: Skin and musculoskeletal.

Obesity is a worldwide issue that many global health authorities consider a growing epidemic. Having a positive correlation between increases in the industrialization of processed foods and sedentary occupations as well as a lack of access to healthcare in poorer socioeconomic areas, obesity is a multifactorial disease affecting several organ systems. The tendency for obesity to cause detrimental changes to the human body is a focal point for healthcare providers to establish more effective clinical treatment and management plans. Implementing comprehensive global educational programs to decrease the prevalence of this unforgiving disease is imperative for a healthier future. Herein, we have provided a comprehensive review of the health effects of obesity upon the human body for the interest of many practicing clinicians managing this health crisis.

The effects of obesity on the human body part II: Nervous, respiratory, and lymphatic systems.

This second installment of The Effects of Obesity on the Human Body considers the nervous, respiratory, and lymphatic systems. Those with obesity face countless psychological hurdles in addition to the respiratory burden and widespread inflammation that can suppress the immune system, resulting in the accumulation of excess fluid in body tissues.

Update on the Biomechanics of the Craniocervical Junction, Part II: Alar Ligament.

STUDY DESIGN: In vitro biomechanical study. OBJECTIVE: The strength of the alar ligament has been described inconsistently, possibly because of the nonphysiological biomechanical testing models, and the inability to test the ligament with both attachments simultaneously. The purpose of this biomechanical model was to reevaluate the alar ligament's tensile strength with both bony attachments, while also keeping the transverse ligament intact, all in a more physiological biomechanical model that mimics the mechanism of traumatic injury closely. METHODS: Eleven fresh-frozen occipito-atlanto-axial (C0-C1-C2) specimens were harvested from individuals whose mean age at death was 77.4 years (range 46-97 years). Only the alar and transverse ligaments were preserved, and the bony C0-C1-C2 complex was left intact. Axial tension was exerted on the dens to displace it posteriorly, while the occipito-axial complex was fixed anteriorly. A device that applies controlled increasing force was used to test the tensile strength (M2-200, Mark-10 Corporation). RESULTS: The mean force required for the alar ligament to fail was 394 ± 52 N (range 317-503 N). However, both the right and left alar ligaments ruptured simultaneously in 10 specimens. The ligament failed most often at the dens (n = 10), followed by occipital condyle rupture (n = 1). The transverse ligament remained intact in all specimens. CONCLUSIONS: When both the right and left alar ligament were included, the total alar ligament failure occurred at an average force of 394 N. The alar ligament failed before the transverse ligament.

The effects of obesity on the human body part III: Cardiovascular, digestive, excretory, endocrine, and reproductive.

This third installment of The Effects of Obesity on the Human Body discusses the endocrine, digestive, reproductive, cardiovascular, and excretory systems. Obesity is known to upset hormonal balance, leading to widespread metabolic disorders involving organs such as the liver and pancreas. Furthermore, the hypersecretion of leptin from adipose tissue triggers various responses from the cardiovascular and gastrointestinal systems, with implications for energy and nutrient balance and uptake.

The Petroclinoid Ligament: Its Morphometrics, Relationships, Variations, and Suggestion for New Terminology.

The anatomy and definition of the petroclinoid ligament (PCL) and its relationship with the abducens nerve are variably described. The goal of this study was to clarify the anatomy of the PCL and better elucidate its relationship with the abducens nerve. Thirty-six sides from 18 fresh-frozen adult cadaveric heads were used in this study. Specimens were all Caucasian and derived from 10 males and 8 females. The mean age at death was 79 years. Dissection of the PCL and abducens nerve was performed using a surgical microscope. The anterior and posterior attachments of the PCL, and position of the abducens nerve were noted. Subsequently, the width, thickness, and length of the ligament, and diameter of the abducens nerve were measured. Thirty-one sides (86.1%) were found to have a PCL, on two sides (5.6%), the PCL was ossified, and on three sides (8.3%), the PCL was absent. The width, thickness, and length of the PCL ranged from 0.54 to 3.39, 0.07 to 0.49, and 3.27 to 17.85 mm, respectively. No PCL had an anterior attachment onto the posterior clinoid process but rather, the clivus. Therefore, based on our findings, the PCL would be better described as the petroclival ligament.

Case Report of a Pelvic Crossed Fused Renal Ectopic Kidney.

Herein we present a case of a horseshoe kidney with crossed fused renal ectopia. Both of these pathologies are congenital anomalies; however, to date, there are few cases that present with both. In this case, discovered during routine dissection, the fused kidney was mostly left-sided and very low in the pelvis. No renal artery arose from the right wall of the abdominal aorta, and the right renal vein drained into the lower part of the inferior vena cava (IVC) where the right and left common iliac veins joined. It is essential for clinicians and surgeons to understand these types of congenital anomalies, as they could impact patient care.

Anatomy, physiology, and updates on the clinical management of constipation.

Clinical management of constipation has evolved from the prescription of dietary supplements, to potent stimulant laxatives, to corrective surgeries for organic blockage. Yet constipation does not respond to a one-size-fits-all treatment. In recent decades, the Bristol Stool Form Scale and Rome III diagnostic criteria have allowed for algorithmic diagnosis, yet these criteria could benefit from further extension and meaningful discussion. This review incorporates pertinent clinical updates and uses the anatomy and physiology of constipation as helpful signposts for the practicing clinician.

Connections Between Amyloid Beta and the Meningeal Lymphatics As a Possible Route for Clearance and Therapeutics.

Alzheimer's disease (AD) is a complex neurodegenerative disorder causing progressive cognitive decline, memory loss, and death of neural tissue. Current research suggests a connection between bulk flow of interstitial fluid and cerebrospinal fluid across the blood-brain barrier and the recently confirmed meningeal lymphatic channels of the brain. The main symptom of interest in AD is the spontaneous aggregation of amyloid beta (Aß) proteins resulting from increased production or lack of clearance from brain tissues. These protein aggregates manifest as plaques in the capillary and artery lumina and the neuronal and dural tissues of the brain, and are known to contribute to cerebral amyloid angiopathy and a host of other neuroinflammatory conditions. The meningeal lymphatics contain a substantial population of immune cells and also serve as a drain into the deep cervical lymph nodes. In this study we discuss the molecular mechanisms by which Aß could gain access to meningeal lymphatic channels through the blood-brain interface, including ways in which it can be cleared to preclude aggregation and plaque deposition.

Ossification of the mamillo-accessory ligament: a review of the literature and clinical considerations.

Ossification of the mamillo-accessory ligament (MAL) is a misunderstood phenomenon; however, many have posited that it can result in nerve entrapment of the medial branch of the dorsal ramus causing zygapophyseal joint related low back pain. The MAL has been studied anatomically by few, yet the data indicate possible associations between ossification of this ligament and spondylosis. It has been proposed that mechanical stress upon the lumbar spine may also lead to progressive ossification of the MAL into a bony foramen.

Ossification of the roof of the porus trigeminus with duplicated abducens nerve.

Ossification of parts of the intracranial dura mater is common and is generally accepted as an age-related finding. Additionally, duplication of the abducens nerve along its course to the lateral rectus muscle is a known, although uncommon anatomical variant. During routine cadaveric dissection, an ossified portion of dura mater traveling over the trigeminal nerve's entrance (porus trigeminus) into the middle cranial fossa was observed unilaterally. Ipsilaterally, a duplicated abducens nerve was also observed, with a unique foramen superolateral to the entrance of Dorello's canal. To our knowledge, there has been no existing report of a simultaneous ossified roof of the porus trigeminus with an ipsilateral duplicated abducens nerve. Herein, we discuss this case and the potential clinical and surgical applications. We believe this case report will be informative for the skull base surgeon in the diagnosis of neuralgic pain in the frontomaxillary, andibular, orbital, and external and middle ear regions.

The simian crease: Relationship to various genetic disorders.

The creases of the palm have been of interest for clinicians, anthropologists, and palmists for hundreds of years, but the variations in them have only been studied during the past 50 years. The simian crease, aptly named for its resemblance to the palmar creases of nonhuman simian primates, has received recognition clinically and anthropologically owing to its abnormal appearance and confounding cytogenetic etiology. Given the rarity of these palmar creases but also their usefulness in diagnosing congenital disorders, discussion of cases of those disorders could provide clinicians with further helpful diagnostic knowledge. This review of the literature focuses on the history, embryology, genetic and hereditary origins, and clinical significance of simian creases for the benefit of the diagnosing clinician. Clin. Anat. 32:1042-1047, 2019. © 2019 Wiley Periodicals, Inc.

Internal Thoracic Artery to Vertebral Artery Bypass Surgery: A Cadaveric Feasibility Study.

OBJECTIVE: Posterior circulation strokes account for over one quarter of all ischemic strokes. The frequency of vertebral artery origin stenosis (VAOS) in patients with vertebrobasilar insufficiency (VBI) has been estimated to be as high 26%-32%, and VAOS is the direct cause of posterior circulation strokes in 9% of patients. This association could have a significant genetic component. This study examines the feasibility of the internal thoracic artery (ITA) as a donor vessel for revascularization in patients with VAOS. METHODS: Ten sides from 5 fresh-frozen white cadaveric necks derived from 3 women and 2 men were used in this study. The mean age of the cadavers at death was 77.2 years (range, 68-88 years). The subclavian artery, vertebral artery, and ITA were dissected. The length and diameter (proximal and distal) of the V1 segment and the length and diameter of the ITA were recorded. Finally, the ITA was transposed to the V1 segment of the vertebral artery (VA1). RESULTS: The mean length of the VA1 and its diameter at the proximal and distal parts were 35.51 and 3.69 mm, respectively. The mean length and diameter of the ITA were 26.53 and 3.27 mm, respectively. Rerouting the ITA to the VA1 was feasible without tension on all sides. CONCLUSIONS: This study indicates that the ITA is anatomically and hemodynamically an excellent option for bypass surgery in a VAOS scenario. We present convincing and reproducible data to aid neurosurgeons in choosing the procedure best suited to their patients.

Pfeiffer type 2 syndrome: review with updates on its genetics and molecular biology.

INTRODUCTION: Pfeiffer syndrome is a rare autosomal dominant inherited disorder associated with craniosynostosis, midfacial hypoplasia, and broad thumbs and toes. The syndrome has been divided into three clinical subtypes based on clinical findings. METHODS: This review will specifically examine the most severe type, Pfeiffer syndrome type 2, focusing on its genetics and molecular biology. CONCLUSION: This subtype of the syndrome is caused by de novo sporadic mutations, the majority of which occur in the fibroblast growth factor receptor type 1 and 2 (FGFR1/2) genes. There is not one specific mutation, however. This disorder is genetically heterogeneous and may have varying phenotypic expressions that in various cases have overlapped with other similar craniosynostoses. A specific missense mutation of FGFR2 causing both Pfeiffer and Crouzon syndromes has been identified, with findings suggesting that gene expression may be affected by polymorphism within the same gene. Compared to other craniosynostosis-related disorders, Pfeiffer syndrome is the most extreme phenotype, as the underlying mutations cause wider effects on the secondary and tertiary protein structures and exhibit harsher clinical findings.

Ectopic Pituitary Adenoma Presenting as a Clival Mass.

Pituitary adenomas are well described in the literature and are frequently observed and treated in clinical practice by neurosurgeons. On the other hand, ectopic adenomas are a diagnostic enigma; a good understanding of anatomy and radiological characteristics is crucial for the successful management of such pathologies. In this paper, we describe the case of a 77-year-old woman who presented with a clival mass invading the left cavernous sinus; we also discuss the associated diagnostic techniques, approaches, imaging options, and characteristics.

Clinical anatomy of the nerve to the mylohyoid.

The nerve to the mylohyoid (NM) originates from the mandibular division of the trigeminal nerve. The NM provides motor control to the mylohyoid and the anterior belly of the digastric. Its sensory component, as a variation of this nerve, has scantly been described in the literature. We discuss the current clinical implications of the NM based on its anatomical variations of the with the hopes of benefiting patients who are undergoing invasive maxillofacial procedures.

Report of an inferior rectal nerve variant arising from the S3 ventral ramus.

In surgical approaches to the perineum in general and anal region specifically, considering the possible variations of the inferior rectal nerve is important for the surgeon. Normally, the inferior rectal nerve originates as a branch of the pudendal nerve. However, during routine dissection, a variant of the inferior rectal nerve was found where it arose directly from the third sacral nerve ventral ramus (S3). Many cases have described the inferior rectal nerve arising independently from the sacral plexus, most commonly from the fourth sacral nerve root (S4); however, few cases have reported the inferior rectal nerve arising from S3. Herein, we describe a variant of the inferior rectal nerve in which the nerve arises independently from the sacral plexus.