The myloglossus in a human cadaver study: common or uncommon anatomical structure?

BACKGROUND: Additional extrinsic muscles of the tongue are reported in literature and one of them is the myloglossus muscle (MGM). Since MGM is nowadays considered as anatomical variant, the aim of this study is to clarify some open questions by evaluating and describing the myloglossal anatomy (including both MGM and its ligamentous counterpart) during human cadaver dissections. MATERIALS AND METHODS: Twenty-one regions (including masticator space, sublingual space and adjacent areas) were dissected and the presence and appearance of myloglossus were considered, together with its proximal and distal insertions, vascularisation and innervation. RESULTS: The myloglossus was present in 61.9% of cases with muscular, ligamentous or mixed appearance and either bony or muscular insertion. Facial artery provided myloglossal vascularisation in the 84.62% and lingual artery in the 15.38%; innervation was granted by the trigeminal system (buccal nerve and mylohyoid nerve), sometimes (46.15%) with hypoglossal component. CONCLUSIONS: These data suggest us to not consider myloglossus as a rare anatomical variant.

Symmetrical anatomical variant of the anterior belly of the digastric muscle: clinical implicat.

The digastric muscle is an important surgical landmark. Several anatomical variants of the digastric muscle are reported in literature and, in particular, the presence of accessory anterior bellies of the muscle is not uncommon. Here, an unreported symmetrical variant of the digastric muscle was found during a dissection of the suprahyoid region. The dissection showed digastric muscles with an accessory anterior belly, which originated from the anterior belly of muscles in proximity and anteriorly to the intermediate tendon. The accessory bellies were fused together on the midline and were attached with a unique tendon to the inner surface of the mental symphysis. These muscles completely filled the submental triangle. This unreported anatomical variant could be considered an additional contribution to description of the anatomical variants of the digastric muscle, with several implications in head and neck pathology, diagnosis and surgery.

Combined transnasal transcervical robotic dissection of posterior skull base: feasibility in a cadaveric model.

The current surgical trend is to expand the variety of minimally invasive approaches and, in particular, the possible application of robotic surgery in head and neck surgery. For this purpose, we explored the feasibility of a combined transcervical-transnasal approach to the posterior skull base, using the da Vinci Surgical System in 3 cadaver heads. Superb visualization of the sellar, suprasellar and clival regions was possible in all three specimens. The trocars` placement through a transcervical port made a more cephalad visualization possible, eliminating the need to split the palate. The advantages of robotic surgery applied to the posterior cranial fossa are similar to the ones already clinically experienced in other districts (oropharynx, tongue base), in terms of tremor-free, bimanual, precise dissection. The implementation of instruments for bony work will definitely increase the applicability of such a system in the forthcoming years.

Endoscopic anatomy of persistent trigeminal artery: a cadaveric study.

BACKGROUND: Persistent trigeminal artery (PTA) is one of the carotid-basilar anastomoses and occasionally complicates vascular or neoplastic pathology. The aim of this study was to become more familiar with the anatomy associated with PTA using an endoscopic view. MATERIAL AND METHODS: PTA was incidentally encountered in a fresh cadaver. Purely endoscopic approaches via supraorbital (extradural and intradural routes), endonasal, and retrosigmoid routes were performed with 4-mm, 0- and 30-degree rigid endoscopes. RESULTS: The PTA belonged to Salas's lateral type and Saltzman's type 1. The supraorbital extradural approach allowed good visualization of the origin and the cavernous portion of the PTA through the infratrochlear triangle. Using the endonasal route, the cisternal portion of the PTA and its confluence to the basilar artery were demonstrated after opening the clival dura; however, the origin of the PTA and the cavernous portion of the PTA were not sufficiently exposed even using a direct approach to the cavernous sinus. The retrosigmoid approach revealed the anatomical relationship among the PTA, trigeminal nerve, and abducent nerve in the petroclival region. CONCLUSION: These 3 endoscopic approaches provided a superb image of the PTA and contribute to the anatomical comprehension of PTA. Additionally, these approaches make us more familiar with an endoscopic view of PTA.

Microsurgical endoscopic-assisted retrosigmoid intradural suprameatal approach: anatomical considerations.

AIM: The aim of this study was to evaluate the feasibility of microscopic endoscopic assisted suprameatal tubercle drilling with a retrosigmoid approach and it focuses on the anatomic structures identified with the endoscope. The advantages of the 30 degrees optic view are also described. METHODS: Fifty dry temporal bones were studied in order to estimate the variability of the prominence of the suprameatal tubercle. Eight fresh cadaveric specimens were prepared for a retrosigmoid approach to allow for microscopic endoscopic assisted suprameatal tubercle drilling. The increase in trigeminal exposure and neurovascular structures visualization with the endoscope, using 0 degrees and 30 degrees optics were then evaluated. RESULTS: Three major types of the suprameatal tubercle were found: 1) a large size tubercle (> 6 mm, 9/50 cases); 2) a medium size tubercle (3-6 mm, 37/50 cases); and 3) an almost absent suprameatal tubercle (< 3 mm, 4/50 cases). Microscopic endoscopic assisted suprameatal tubercle drilling with opening of the Meckel's Cave was found to be technically feasible in all cases. The increase in trigeminal nerve exposition was of 9 mm on average. Endoscopic exploration with 0 degrees and 30 degrees optics made possible the identification of all neurovascular structures in the area. CONCLUSION: Microscopic endoscopic assisted suprameatal tubercle drilling is a feasible procedure that allows the identification of all neurovascular structures in the cerebellopontine angle and petrous apex region. The opening of Meckel's Cave may be particularly useful for lesions located in the cerebellopontine angle having a minor component that extends anteriorly and laterally in the middle cranial fossa.

The microvascular network of the pituitary gland: a model for the application of fractal geometry to the analysis of angioarchitecture and angiogenesis of brain tumors.

In geometrical terms, tumor vascularity is an exemplary anatomical system that irregularly fills a three-dimensional Euclidean space. This physical characteristic, together with the highly variable vessel shapes and surfaces, leads to considerable spatial and temporal heterogeneity in the delivery of oxygen, nutrients and drugs, and the removal of metabolites. Although these biological features have now been well established, quantitative analyses of neovascularity in two-dimensional histological sections still fail to view tumor architecture in non-Euclidean terms, and this leads to errors in visually interpreting the same tumor, and discordant results from different laboratories. A review of the literature concerning the application of microvessel density (MVD) estimates, an Euclidean-based approach used to quantify vascularity in normal and neoplastic pituitary tissues, revealed some disagreements in the results and led us to discuss the limitations of the Euclidean quantification of vascularity. Consequently, we introduced fractal geometry as a better means of quantifying the microvasculature of normal pituitary glands and pituitary adenomas, and found that the use of the surface fractal dimension is more appropriate than MVD for analysing the vascular network of both. We propose extending the application of this model to the analysis of the angiogenesis and angioarchitecture of brain tumors.

Transnasal approach to the medial intraconal space: anatomic study and clinical considerations.

BACKGROUND: The aim of this study was to illustrate the anatomy of the medial compartment of the orbit by comparing the endoscopic transnasal perspective with the external ones. METHODS: 8 orbits from 5 double-injected heads were carefully dissected. An endoscopic anterior transconjunctival dissection was performed in one orbit while an endoscopic transnasal intraconal dissection was conducted in 3 orbits. External dissections (from medial, superior and anterior perspective) were also performed. RESULTS: The role of the medial rectus muscle is emphasised. It represents the first important landmark encountered, covering all the other structures during transnasal approaches. By displacing it, the medial intraconal space with its contents becomes visible: the ophthalmic artery and related branches, the superior ophthalmic vein, the nasociliary nerve and, in the deepest part of the medial compartment, the optic nerve. CONCLUSION: The medial compartment of the orbit can be addressed transnasally. By displacing the medial rectus muscle, it is possible to gain adequate space for the instruments and to control all of the medial compartment, including the medial aspect of the optic nerve.

Endoscopic transnasal anatomy of the infratemporal fossa and upper parapharyngeal regions: correlations with traditional perspectives and surgical implications.

BACKGROUND: The aim of this study was to illustrate the endoscopic surgical anatomy of the infratemporal fossa (ITF) and upper parapharyngeal space and to provide useful landmarks by comparing transnasal perspectives with external ones. MATERIALS AND METHODS: 6 fresh double injected heads were dissected. External lateral dissection was performed through a pre-auricular skin incision while external anterior dissection started with a modified Weber-Ferguson incision. External medial to lateral dissection was performed starting from the rhinopharyngeal and pterygoid regions, after cutting the specimen in 2 halves passing through the nose. Endoscopic dissection was performed through an endonasal approach (0° and 45° scopes). RESULTS: Among all the structures identified during the dissection, the most useful landmark when dissecting the ITF in a lateral to medial direction is the lateral pterygoid muscle. In anterior approaches (mostly endoscopic) the role of the lateral pterygoid muscle is less important and the Eustachian tube (ET) represents the most important landmark to point out the upper portion of the parapharyngeal internal carotid artery (ICA). The role of the ET, in lateral dissection is, on the contrary, by far less important given the fact that it is very deep in the surgical field and that the ICA is encountered earlier during surgical approaches. Another crucial landmark during anterior endoscopic surgery is the vidian nerve because it points to the anterior genu of the internal carotid artery. CONCLUSION: The complex 3-dimensionality of the ITF and the upper parapharyngeal space needs a sound knowledge of the surgical anatomy. The role of the same landmarks changed in different approaches. The ability to orientate oneself in this complex area is related to an accurate knowledge of its anatomy through comparison of endoscopic and external perspectives.

Intraosseous anastomosis in the maxillary sinus.

AIM: During sinus-lift surgery, certain intra-osseous vessels may be accidentally cut and this cause bleeding complications in approximately 20% of osteotomies. Therefore, understanding vascular details of the maxilla is very important for the surgeon. Here, we have given an anatomical overview of maxillary sinus vascularization through anatomical dissection. We have analyzed the distribution, localization and distance from the alveolar ridge of intraosseous branches of the maxillary artery found during sinus lift surgery. METHODS: Fifty-six maxillary bone doors were made bilaterally in twenty-eight unfixed cadavers; the doors were made between the first molar and the second molar (24 doors) or between the first and the second premolar (32 doors). RESULTS: Intraosseous arteries were found in 37 maxillary bones (66%). The average height of the artery from the alveolar crest was 13+/-3.2 mm in the distal doors and 18 +/- 6.1 mm in the mesial doors. Generally, the intraosseous maxillary branches ran caudo-rostrally; but in five maxillae, we found two parallel arteries, while in three cases the maxillary artery ran vertically. No differences were found between the left and right side. CONCLUSION: The risk of vascular damage in sinus floor elevation surgery is a real problem for the oral surgeon. Detailed anatomical knowledge about sinus vascularization is very important to reduce the risk of vascular damage and bleeding. In addition the visualization of sinus anastomosis by radiology and less invasive surgery, such as piezo-surgery, could be helpful.

Anatomical structures to provide passive motility of peripheral nerve trunks and fascicles.

It is well known that tendons have to be able to move if the muscle contracts. It is still not generally known that any structure in the body has to be able to move passively against other structures. This is especially important for the movement of limbs. In a monoaxial joint like the humero-ulnar joint only structures in the plane of the joint axis remain fixed. Structures in a certain distance to the flexion or to the extension side have to be able to move against other structures in different levels. The amount of passive motion is dependent on the distance to the plane of the joint axis. Tissues which provide a frictionless passive motion are discussed.

Anatomic position of the asterion.

OBJECTIVE: The asterion is defined as the junction of the lambdoid, parietomastoid, and occipitomastoid sutures. The asterion has been used as a landmark in lateral approaches to the posterior fossa. However, its reliability as a landmark comes into question considering the apparent variability of its position. This study was performed to determine the reliability of the asterion as a surgical landmark. METHODS: One hundred dried skulls were obtained for study. A 2-mm drill hole was placed at the asterion on each side. The position of the drill hole on the inner surface of the skull was next determined and recorded. RESULTS: The asterion was located over the posterior fossa dura in 32% on the right and 25% on the left. Its position was over the transverse or sigmoid sinus complex in 61% on the right and 66% on the left. The landmark was located above the transverse-sigmoid sinus complex in 7% on the right and 9% on the left. CONCLUSIONS: The asterion is not a strictly reliable landmark in terms of locating the underlying posterior fossa dura. Its location is very often directly over the transverse-sigmoid sinus complex. Burr holes placed at the asterion may often open the bone directly over the sinus, leading to potential damage.

Surface and superficial surgical anatomy of the posterolateral cranial base: significance for surgical planning and approach.

We have performed an anatomic study, 15 using fixed cadaveric preparations, with the goal of identifying surface landmarks that will reliably locate the underlying transverse and sigmoid sinus complex. Simple morphometric relationships were first determined on both sides of each specimen to yield 30 sides measured. The following relationships were determined: 1) zygoma root-asterion, 2) asterion-mastoid tip, 3) zygoma root-suprameatal spine (Henle's spine), 4) asterion-suprameatal spine, 5) mastoid tip-suprameatal spine. The relationship of the asterion to the transverse-sigmoid junction was determined by bone removal. Also, the distances from the asterion to the sigmoid sinus-superior petrosal sinus junction and the superior margin of the transverse sinus were studied. Surface and marks were found to have definitive relationships to underlying anatomic substrates in all specimens studied. The critical relationships that were concluded from this study can be described in terms of two easily identified lines between bony surface structures. A line drawn from the zygoma root to the inion, i.e., the superior nuchal line, reliably located the rostrocaudal level of the transverse sinus in all specimens. Although the asterion did not consistently fall on this line, the transverse-sigmoid junction could reliably be placed at the anteroposterior level of the asterion. Further, a line drawn from the squamosal-parietomastoid suture junction to the mastoid tip reliably defined the axis of the sigmoid sinus through the mastoid. We also found that the junction of the squamosal and parietomastoid sutures lay over the anterior border of the upper curve of the sigmoid sinus. The anterior portion of the supramastoid crest correlated with the level of the middle fossa. These surface relationships all have significance for posterolateral approaches to the cranial base. Since performing this study, these relationships have been found reliable for operative planning in our clinical cases.

Two-port endoscopy of the middle ear: endoscopic anatomy.

OBJECTIVES: To shed light on the endoscopic anatomy of the middle ear seen on 2-port endoscopy and to describe potential clinical applications. DESIGN: Anatomical structures were visualized by transmeatal or transtympanic rigid scopes of different angles and by a flexible scope in the eustachian tube. This arrangement ensured reciprocal guidance of the scopes and provided access to regions not seen otherwise. SETTING: The Department of Anatomy 1, University of Vienna, Vienna, Austria. MATERIALS: Forty tympanic cavities obtained from cadaver skulls without prior fixation were examined. Specimens did not show any abnormalities and were chosen without regard to age or sex. RESULTS: Depending on the angle of view, rigid transmeatal or transtympanic endoscopes provided a full view of the entire tympanic cavity except for the epitympanum, access to which was barred by the incudomallear joint, the mallear folds, and the tympanic chord, but the epitympanum was well visualized through the flexible, steerable, transtubal scope. CONCLUSIONS: Two-port endoscopy of the middle ear offers a full view of all structures in the tympanic cavity. The atraumatic transtubal approach to the tympanic cavity enhances the safety of transmeatal interventions and facilitates postoperative follow-up.

The course of the prevertebral segment of the vertebral artery: anatomy and clinical significance.

BACKGROUND: The so called "pretransverse or prevertebral segment" of the vertebral artery is defined from its origin at the subclavian artery to its entry into the respective transverse foramen. In surgery, angiography, and in all noninvasive procedures it is of great importance to know the exact details of the course and the origin of this segment of the vessel as well as in which percentages real abnormalities can be found. METHODS: The VI segment of the vertebral artery was investigated both in anatomic preparations and clinical studies. A total of 402 vertebral arteries were evaluated (70 anatomic preparations in different forms, 181 patients, 95 angiographies of the aortic arch, and 86 color coded doppler sonographies). RESULTS: A contorted course was found in 157 (39%) cases. The plane of tortuosities demonstrated by the respective vessels was found to be horizontal in 40 (44.9%) cases, sagittal in 30 (33.7%) cases, and frontal in 19 (21.4%) cases. In 51 (32.5%) cases the contorted pathway was on the right side, and in 106 (68%) cases, on the left. A hypoplasia was found in 16 (10%) cases--11 (4.8%) right and 5 (2.2%) left. We further differentiated the convexity lying either medially or laterally in the transverse or frontal plane, or oriented dorsally or ventral in the sagittal plane. The exact location of the origin of the artery on the circumference of the subclavian artery (47% cranial, 44% dorsal, 3% ventral, 6% caudal) and also the average values of length and diameter are described. No significant differences between tortuous and nontortuous vessels were found with respect to length and diameter. A real abnormality of the origin of the vertebral artery was found in 8 (3.5%) cases. CONCLUSIONS: The described morphologic variations and frequencies of the VI segment of the vertebral artery have clinical applications in a wide field of pathologies in that region. To know about these findings seems to be very important not only in diagnosis (angiography, color coded doppler sonography) but also in their surgical and endovascular treatment.

The vertically based deep fascia turnover flap of the leg: anatomic studies and clinical applications.

Although fasciocutaneous turnover flaps are a simple and fast method for covering soft-tissue defects of the lower leg, many reconstructive surgeons have their doubts about them. They revolve around the lack of criteria for safely designing these random-pattern flaps and around the risk of donor site problems. A vertically based deep fascia turnover flap with a paratibial or parafibular pedicle is presented. Anatomic studies of 36 injected lower limbs showed the deep fascia to be supplied by a mean of 61 vessels. As musculofascial, septofascial, and periosteofascial branches, these contribute to a richly anastomosing vascular network within the deep fascia. Along the deep transverse septum at the medial tibial border, the anterior and posterior peroneal septa, and between the anterior tibial and extensor muscles, the fascia is supplied by segmental vessels in a clearly defined arrangement. Pedicled on these vessels, the deep fascia is a useful candidate tissue for transversely oriented turnover flaps. These are particularly well suited for covering pretibial or prefibular soft-tissue defects. Unlike adipofascial turnover flaps, the transversely oriented deep fascia turnover flap keeps its subcutaneous layer with its intact vascular plexus so that the overlying skin is adequately perfused even in patients with sizable flaps or an extremely thin skin. Clinical experience with the vertically based paratibial or parafibular deep fascia turnover flap in six patients confirmed its usefulness for covering small to medium-sized soft tissue defects of the lower leg.

Scarpa's fascia flap: anatomic studies and clinical application.

Fascia and fascia-subcutaneous flaps are thin, pliable, and well-vascularized tissue with aesthetic and functional advantages, particularly for the extremities and in the head and neck region. Although various donor sites have been used for these flaps, there is an occurrence of unsatisfactory donor-site defects that are often complicated by conspicuous, widened scars or alopecia. In addition, flap elevation is sometimes prolonged because of the demanding operative procedures as well as the impossibility of a two-team approach. In this anatomic and clinical study we present a new fascial flap that results in a minimal donor-site defect and a short and easy operative procedure. Scarpa's fascia, which can be used as both a free and a pedicled flap, is a well-defined single membranous sheet within the subcutaneous tissue layer at the lower abdominal wall. We studied its distribution, structure, and vascular supply in 27 fresh cadaver specimens. In addition, computed tomographic (CT) and ultrasound studies were performed in 13 healthy volunteers and in 3 cadavers before and after injection of diluted contrast material in the superficial epigastric artery. Finally, histologic examinations were done with hematoxylin and eosin or with reticulum and elastin. Our studies showed that Scarpa's fascia provides a thin, pliable, and well-vascularized flap pedicled on the superficial epigastric artery. After successful application of the Scarpa's fascia flap as a free flap in 3 patients and as a pedicled option in 1 patient, we can recommend this flap as a valuable tool for the reconstructive surgeon.

Endoscopic anatomy of the ventricles.

The endoscopic view offers a new anatomical dimension to the neurosurgeon. The fact makes it basically necessary to study the topographic anatomy under endoscopic conditions. In this paper attention was drawn to the ventricles because they are the most common region of clinical application. In 25 specimens neuroendoscopic explorations of the ventricles have been done. The dissections have been carried out through one- and two burr hole approaches (two working endoscopes at the same time). The instrumentation includes rigid 4 mm and 6 mm endoscopes. The procedures have been documented by continuous video recording and parallel photography.

Neuroanatomical details under endoscopical view--relevant for radiosurgery?

Both, neuroendoscopy and radiosurgery, are upcoming techniques in neurosurgery and become nowadays more and more important. In planning radiosurgical interventions it is very important to have both, the information about the morphology of the pathology itself, and also a clear understanding from the surrounding structures. Neuroendoscopic techniques gives the possibility to demonstrate well known structures without prior dissection. This paper focuses on these anatomical informations which might be relevant in planning further radiosurgical interventions especially in cases of the vascularization of the cranial nerves and the arachnoid membranes, these structures appears much more complex than described in "common" neuroanatomical textbooks. Endoscopic techniques also better demonstrate the real in vivo relationships and gives so a better understanding for interpreting "planning" MRI and CT scans. We therefore consider that neuroanatomical studies under a neuroendoscopical view are very important and could be very helpful in planning radiosurgical intervensitons.

[Hydatid torsion as a cause of acute scrotum--clinical, sonographic and anatomic aspects]. / Hydatidentorsion als Ursache des akuten Skrotums--klinische, sonographische und anatomische Aspekte.

Out of 82 patients with acute swelling of the scrotum, 25 (30.5%) had hydatid torsion. Hydatid torsion was the second most common cause of acute scrotal swelling in the entire patient group. In the group of patients up to 14 years of age (n = 36), hydatid torsion was found in 47.2% and was the most common cause of acute scrotal swelling, followed by torsion of the spermatic cord. Only 3 patients had torsion of an appendage of the epididymis. All other patients (n = 22) had torsion of the hydatid of Morgagni (appendage of the testicle). A difference in anatomical structure and vascularization during childhood seems to be the most important aspect regarding hydatid torsion and hemorrhagic infarction. Ultrasonographic examination of the scrotum and checking to see if the typical physical signs are present can help in making the exact diagnosis. In 13 patients with hydatid torsion, the scrotum was examined with ultrasound high-frequency transducers (7.5, 10 and 12 MHz). In 4 patients, the diagnosis was hydatid torsion, as determined by ultrasonography. Two patients were treated conservatively with a daily follow-up including a clinical examination and investigation of the scrotum with ultrasound. The patients recovered very quickly and the acute symptoms resolved within a few days in virtually all instances. Thus, in cases where the diagnosis is proven and the course of the disease is reasonably mild and painless, conservative management of intrascrotal hydatid torsion is possible and can be an effective means of treatment in lien of surgical intervention.

The natural evolution of endoscopic approaches in skull base surgery: robotic-assisted surgery?

The current surgical trend is to expand the variety of minimally invasive approaches and, in particular, the possible applications of robotic systems in head and neck surgery. This is particularly intriguing in skull base regions. In this paper, we review the current literature and propose personal considerations on the role of robotic techniques in this field. A brief description of our personal preclinical experience on skull base robotic dissection represents the basis for further considerations. We are convinced that the advantages of robotic surgery applied to the posterior cranial fossa are similar to those already clinically experienced in other areas (oropharynx, tongue base), in terms of tremor-free, bimanual, precise dissection: the implementation of instruments for bony work and resolving current drawbacks will definitely increase the applicability of such a system in forthcoming years.