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The literature lacks a comprehensive review of the petrosal nerves, which often have a complicated course and nomenclature. The medical literature was reviewed comprehensively for information regarding the anatomy, pathology, and surgery of the petrosal nerves. The terminology and anatomy of the petrosal nerves are often complicated. Our review found multiple nomenclatures used in the description of these structures. Information regarding the petrosal nerves may assist those who observe or operate at or near the skull base. To our knowledge, this is the first comprehensive review of these structures., (Copyright 2009 Wiley-Liss, Inc.)

Variations within the musculature of the lateral compartment of the leg are uncommon. However, clinicians and radiologists should be aware of anatomical alterations in this region when involved in diagnosis or imaging interpretation. The present report describes a well-developed muscle of the lateral compartment of the leg that inserted distally onto the talus and calcaneus. This muscle could be considered a variation of the so-called peroneus quartus muscle. To the authors' knowledge this muscle variation has not been described as having an attachment onto the talus thus the term 'peroneotalocalcaneus muscle' is proposed.

Introduction: Replacement sources for calvarial defects include synthetic materials, donor grafts, and autologous bones such as ribs or split-thickness calvarial cranioplasty. When these sources are not available or are inadequate, other structures or sites would be desirable. However, and to our knowledge, the scapula has not been explored as a potential source for calvarial reconstruction. Therefore, the following study was performed to verify the utility of this bone for cranioplasty., Materials and Methods: Six adult (mean age 71 years) cadavers (four formalin-fixed and two fresh specimens) were used in this study. In the prone position, an incision was made over the midpart of the infraspinous fossa. Soft tissues were then removed from the anterior and posterior aspects of the scapula in this region avoiding the glenohumeral articulation superiorly. Previously made cranial defects were then filled using available scapula as a bony replacement., Results: An average of 9 x 12 x 7 cm of scapula was available for harvest inferior to the glenohumeral joint. Lateral and medial borders of the scapula were found to have a mean thickness of 9 mm. No obvious injury to surrounding vessels or nerves was found using this procedure and good coverage of calvarial defects was afforded by this bony replacement., Conclusions: Such a bony substitute as autologous scapula might be of utility when other replacements are not available or are of a limited size. Examples of such a use would include patients in whom a hemispheric bone flap is lost. Following clinical confirmation, the neurosurgeon may wish to consider the scapula as an alternative site for bone harvest for cranioplasty as this was a feasible technique in the cadaver.

Introduction: A review of the ancient world finds multiple documentations describing the use of the human calvaria as a drinking implement., Terminology: This term, which is frequently and incorrectly called the "calvarium," has a unique history among multiple cultures of the world. For example, the purported site of Jesus' crucifixion "Calvary" is derived from this term calvaria. The present report explores the derivation, misuse, and history of the human calvaria.

There is scant information in the literature regarding the transverse genicular ligament. In order to elucidate further the anatomy and controversial function of this structure, we dissected 28 cadavers. This ligament was identified in 55% of knee joints. Morphometrically, we found a mean length and width of this ligament of 35.4 and 2.5 mm, respectively. Two (3.7%) specimens were found to have a duplicated ligament. The mean distance between the anterior attachment site of the anterior cruciate ligament onto the tibia to the transverse genicular ligament was 2.5 mm and the mean distance to this ligament to a midpoint of the tibial tuberosity was 40.5 mm The transverse genicular ligament was found to be slightly taut in extension and lax in flexion of the knee joint. Lateral and medial forces applied manually to the knee had no effect on this ligament. No tension was noted of the transverse genicular ligament with rotation of the knee. With transection of the ligament, no discernable difference in the integrity of the knee joint was observed. The mean tensile strength of this ligament was 67 N. Based on our study, the transverse genicular ligament plays a minimal part in the proper function of the knee joint. Moreover, with only approximately one-half of the knees in our study harboring this structure, one would expect a significant portion of the population to exhibit signs of biomechanical dysfunction of the knee joint which is not the case. This structure may represent a vestigal/insular part of the mesenchyme forming the menisci.

A venous anastomotic network is occasionally found at the base of the brain, which closely resembles the vicinal arterial circle of Willis. When present, this venous polygon is composed of the anterior cerebral and communicating veins, the basal vein of Rosenthal and the posterior communicating and lateral mesencephalic veins. We propose that this anastomotic ring be termed the venous circle of Trolard. This venous circle might cause bleeding with such procedures as an endoscopic third ventriculostomy. We believe that information regarding this venous circle may be useful to neuroradiologists or neurosurgeons operating at the base of the brain (Fig. 1, Ref. 10). Full Text (Free, PDF) www.bmj.sk.

Esmail Jorjani was an influential Persian physician and anatomist of the 12th century who did most of his writing after his seventh decade of life. Jorjani's comprehensive textbook of medicine, Zakhirey-e Khwarazmshahi (The Treasure of the Khwarazm Shah) was written in approximately AD 1112 and is considered to be the oldest medical encyclopedia written in Persian. This was an essential textbook for those studying medicine during this time. We describe the life and times of Jorjani and provide a translation and interpretations of his detailed descriptions of the cranial nerves, which were written almost a millennium ago. Medieval Persian and Muslim scholars have contributed to our current knowledge of the cranial nerves. Some of these descriptions, such as the eloquent ones provided by Jorjani, were original and have gone mostly unknown to post-Vesalian European scholars.

The basilar venous plexus is the anteromedian venous channel of the posterior cranial fossa that has many conflicting and brief descriptions in the extant literature. To our knowledge, no single study has been performed that analyzed this venous structure in detail. The aim of the current study was to elucidate further the anatomy of this structure of the posterior cranial fossa. The authors examined twenty adult cadaveric specimens following injection of the internal jugular veins or cavernous sinus to observe the morphology of the basilar plexus. All specimens were found to have a basilar plexus which was always plexiform and very variable in nature. This structure was dorsal to the clivus superiorly and dorsal clivus and overlying tectorial membrane inferiorly. The mean diameter of the channels making up this plexus was 1.1 mm. Communication was always found between the basilar plexus and the inferior petrosal sinuses and this was the primary route used to drain the basilar sinus out of the cranium. In fact, these two venous structures were more or less contiguous across the midline at multiple levels. In seven specimens (35%), the basilar plexus communicated with veins draining into the hypoglossal canal. The basilar plexus communicated with the marginal sinus in 12 specimens (60%). This plexus became much less concentrated as it descended inferior to a plane between the jugular tubercles. No specimen was found to have connections with veins of the anterior brain stem or ventral surface of the clivus. The basilar plexus is a highly variable posterior fossa venous structure. Clinicians and radiologists should take into account this variability when managing cerebral venous disorders or interpreting imaging studies of the skull base.

Few reports are found in the extant medical literature regarding the vastoadductor membrane. This membrane effectively creates a subcompartment within the subsartorial canal. The lower limbs of 16 embalmed adult cadavers were dissected to identify the vastoadductor membrane and note its measurements. A vastoadductor membrane was identified in all specimens and was derived from the medial intermuscular septum. This membrane connected the medial edge of the vastus medialis muscle to the lateral edge of the adductor magnus muscle. Membranes were all wider proximally and narrowed distally. The mean length of this structure was 7.6 cm. The mean width of the vastoadductor membrane at its proximal, midportion, and distal parts was 2.2, 1.7, and 0.5 cm, respectively. The mean distance from the anterior superior iliac spine to the proximal border of the vastoadductor membrane was 28 cm. The mean distance from the distal border of the membrane to the adductor tubercle was 10 cm. Seventy-five percent of specimens exhibited a fenestrated vastoadductor membrane. Branches of the saphenous nerve to the skin of the medial thigh pierced the vastoadductor membrane in 31% of specimens. Two specimens demonstrated branches derived from the branch of the obturator nerve that pierced this membrane en route to the skin of the medial thigh. Perforating venous branches from the great saphenous vein were identified in 22% of specimens. As compression of the femoral artery at the adductor hiatus is a well-recognized entity, the clinician may also try to explore potential compression of this vessel more proximally by an overlying vastoadductor membrane. The authors would also hypothesize that due to the interconnection between the adductor magnus and vastus medialis by the vastoadductor membrane that a potential synergy exists between the functions of these two muscles.

Discrepancies abound in the literature regarding the anatomy and incidence of the C1 dorsal roots, ganglia, and rami. The present study was performed to elucidate further the detailed anatomy of these structures and to review their clinical relevance. Thirty-adult cadavers were used for this study. The mean age for this group was 72 years. C1 and C2 spinal nerves were identified in 100% of the specimens examined. In 46.6% of specimens, C1 dorsal rootlets were identified and of these, 28.5% had an associated dorsal root ganglion. In 50% of specimens, the spinal accessory nerve joined with dorsal rootlets of C1. C1 in these cases did not possess a dorsal root ganglion. There were no significant differences between left sides, gender, and age (P > 0.05). Additional knowledge regarding the C1 dorsal roots, ganglia, and rami may be of use to the clinician who treats various pain syndromes including medically and surgically intractable occipital neuralgia.

There is significant paucity in the literature regarding the vertebral nerve. Moreover, descriptions of this structure are conflicting. To evaluate further the anatomy and potential clinical significance of this structure, 10 fresh adult cadavers (20 sides) underwent dissection and macroscopic observation of this structure. All specimens were found to have a vertebral nerve that originated from the stellate ganglion with the exception of two left sides (10%) in which this nerve arose from the inferior cervical ganglion. This nerve ascended posteromedial to the vertebral artery. The vertebral nerve was found to be, in essence, a long and deep gray ramus communicans that connected most commonly the stellate ganglia to C6 or C7 spinal nerves by passing through the C6 and C7 transverse foramina. Fifteen percent of sides were found to have a vertebral nerve that was plexiform in its configuration. Fifty percent were found to have very small branches that entered the fibrous capsule of adjacent zygapophyseal and intervertebral joints. Some specimens were noted to have meningeal branches of the vertebral nerve. Based on our observations, the vertebral nerve is simply a deep ramus communicans, which often provides articular and meningeal branches to the adjacent spine. As neck pain is a significant reason for physician office visits, additional knowledge of the nerves innervating the joints and adjacent meninges of the neck could be important for both surgical and medical blockade of nerve fibers.

With recent laparoscopic advancements in retroperitoneal and thoracic surgical procedures, familiarity with major lymphatic structures, such as including the cisterna chyli (CC) and thoracic duct (TD), has proven beneficial in avoiding misdiagnosis and iatrogenic intraoperative injury. In this light, the aim of our study was to explore and delineate the topography of the CC, classify the different patterns of lymphatic tributaries, and categorize its varying location with respect to the vertebral bodies. The anatomy of the CC was examined in 120 adult human cadavers. The CC was found in 83.3% of the specimens and both the tributaries of the CC and the location, with respect to vertebral level, demonstrated wide variation. The results were classified into four types. The most common tributary configuration (type I), found in 45% specimens, was a single CC formed by the union of the left lumbar trunk (LT) and the intestinal trunk (IT). In 30% the CC was formed where the IT opened into the TD and the right lumbar trunk (RT), LT, retroaortic nodes (RN) and branches from the intercostal lymphatics (IL) joined variably (type II). In 20% the CC was formed by the junction of the RT and IT (type III), while in 5% there was a variable confluence pattern of lymphatic trunks that could not be classified (type IV). The CC was located at L1-L2 (type A) in 63%, T12-L1 (type B) in 21%, T11-T12 (type C) in 8%, T10-11 (type D) in 5%, and T9-10 (Type E) in 3%, of the specimens. The CC was found in the retrocrural space and, in 75% of the cases, to the right of the abdominal aorta. We hope that the data supplied by this study will provide useful information in the future to anatomists, radiologists and surgeons alike.

The infratemporal fossa is often the site of pathology or surgical intervention. We describe an unusual muscle found during the routine dissection of the right infratemporal fossa. The literature germane to this variable muscle, best described as a variant of the pterygoideus proprius, is reviewed. The clinician may contemplate the wide array of muscular anomalies within the infratemporal fossa when considering unexplained neurological symptoms attributed to branches of V3 and pursue appropriate diagnostic testing.

Microsurgical approaches to the skull base require a thorough knowledge of the microvasculature of this region. Interestingly, most standard texts of anatomy do not mention the branches of the internal carotid artery as it travels through the temporal bone and cavernous sinus. Although small and with often conflicting descriptions, these arterial branches may be of significance when contributing to the vascular supply of such pathological entities as meningiomas and vascular malformations. Furthermore, multiple anastomoses exist between these branches and branches of the external carotid artery, thus providing a potentially important collateral circulation between these two systems and thus retrograde flow needed to maintain the patency of the distal internal carotid artery (ICA) when this vessel is obstructed proximally. We review the literature regarding these branches of the internal carotid artery and their clinical significance.

Wilhelm Erb is well known for his early contributions to the field of neurology and was an eminent physician of his time. One area described by him and that still bears his name is Erb's point. This point located just superior to the clavicle was used by Erb to transcutaneously elicit contractions of various proximal arm muscles with electrical stimulation. Many have mistakenly interchanged the terms "Erb's point" and "nerve point" when describing the point of emergence of the cutaneous branches of the cervical plexus near the posterior border of the sternocleidomastoid muscle. We present a brief history of Erb's adult life and review his original description of his supraclavicular point and contrast this to the so called nerve point of the posterior cervical triangle. Clinicians and anatomists should be aware of the discrepancy often found in the literature between these two terms., (Copyright 2006 Wiley-Liss, Inc.)

Object: The superior and inferior sagittal sinuses have been well studied. Interestingly, other venous structures within the falx cerebri have received scant attention in the medical literature. The present study was performed to elucidate the presence and anatomy of these midline structures., Methods: The authors examined 27 adult latex- or ink-injected cadaveric specimens to observe the morphological features of the sinuses within the falx cerebri (excluding the inferior and superior sagittal sinuses)., Results: All specimens were found to have an extensive network of small tributaries within the falx cerebri that were primarily concentrated in its posterior one third. In this posterior segment, these structures were usually more pronounced in the inferior two thirds. The portion of the falx cerebri not containing significant falcine venous sinus was termed a "safe area." These vascular channels ranged in size from 0.5 mm to 1.1 cm (mean 0.6 mm); 100% of these vessels communicated with the inferior sagittal sinus. Classification of the structures was then performed based on communication of the falcine venous sinus with the superior sagittal sinus. Type I falcine sinuses had no communication with the superior sagittal sinus, Type II falcine sinuses had limited communication with the superior sagittal sinus, and Type III falcine sinuses had significant communication with the superior sagittal sinus. Seventeen (63%) of 27 specimens communicated with the superior sagittal sinus (Types II and III). Further subdivision revealed 10 Type I, seven Type II, and 10 Type III falcine venous plexuses., Conclusions: There are other venous sinuses in the falx cerebri in addition to the superior and inferior sagittal sinuses. Neurosurgical procedures that necessitate incising or puncturing the falx cerebri can be done more safely via a described safe area. Given that the majority of specimens in the authors' study were found to have a plexiform venous morphology within the falx cerebri, they propose that these channels be referred to as the falcine venous plexus and not sinus. The falcine venous plexus should be taken into consideration by the neurosurgeon.

Additional localizing superficial landmarks for intracranial structures can be of use to the neurosurgeon. This study was performed to evaluate the usefulness of the superficial temporal artery (STA) as an external landmark for deeper brain structures. Thirteen adult cadavers (26 sides) underwent latex injection of their STA bilaterally. Dissections were next carried out to identify this vessel. Once the STA and its frontal and parietal branches were skeletonized, craniectomies were performed and the underlying dura mater excised. Measurements were made between the frontal and parietal branches of the STA and deeper brain structures. The STA was found to branch on average 3 cm superior to the tragus. The bifurcation of the STA was found to commonly bifurcate at the level of the floor of the middle cranial fossa or superior temporal gyrus. The Sylvian fissure was found at a mean of 2 cm superior to the STA bifurcation. The angle between the frontal branch of the STA and the zygomatic arch had a mean of 37 degrees. The angle between the frontal and parietal branches of the STA had a mean of 87 degrees. At the level of the glabella, the frontal branch of the STA was on average 3 cm posterior to the frontal pole. The temporal tip was located a mean of 3.2 cm anterior to the frontal branch of the STA. The plane of the foramen of Monro was found to lie at a mean distance of 2.3 cm posterior to the frontal branch of the STA. The parietal branch of the STA was noted to travel more or less parallel with the central sulcus in all specimens and to travel an average of 2 cm posterior to this sulcus. At the level of the lateral attachment of the tentorium cerebelli, the parietal branch of the STA was found to travel a mean of 4.8 cm anterior to the entrance of the vein of Labbé into the transverse sinus. The parietal branch of the STA was also found to travel a mean of 4.2 cm anterior to the angular gyrus and 3.9 cm anterior to the supramarginal gyrus. Palpation or Doppler identification of the STA and its branches with subsequent mapping on the lateral cranium may prove useful as an additional superficial landmark for the neurosurgeon., (Copyright 2006 Wiley-Liss, Inc.)

We report a 79-year-old female cadaver found to harbor an indirect inguinal hernia involving the urinary bladder. Further investigation revealed a patent canal of Nuck. The authors describe this rare finding in an adult and review the pertinent literature regarding such herniation. We believe this to be the first report of an indirect inguinal hernia involving the urinary bladder in a cadaver. This also seems to be the first description of such a hernia via a patent canal of Nuck in an adult.

Persistence of fetal intracranial arteries is rare. We review this anatomical literature regarding the persistence of the trigeminal artery and discuss the findings in two cadaveric cases both found to harbor this vessel. This anomaly should be considered by the clinician and anatomist who view imaging of the skull base. Additionally, the relationships between such an artery and other structures within the cavernous sinus should be understood by the neurosurgeon who operates in this region, e.g., transsphenoidal approaches to the skull base.

Object: The basal vein of Rosenthal (BV) courses from the premesencephalic cistern, through the ambient cistern, and terminates in the quadrigeminal cistern. The aim of this study was to describe and quantitate the surgical anatomy of this structure and specifically to provide landmarks for identifying this vessel along its course. These data may be of use, for example, to surgeons using subtemporal operative approaches through regions where this vessel is concealed., Methods: The authors examined 15 latex-injected adult cadaveric brains (30 sides) to delineate the morphological characteristics of the BV. Dissections of the BV were then performed and measurements were made between this structure and the tentorial incisura at the anterior, middle, and posterior borders of the lateral midbrain. All specimens were found to have a left and right BV with varying morphological characteristics. The mean distance between the BV and posterior cerebral artery at the midpoint of the lateral midbrain was 16 mm. The BV was always found superomedial to the posterior cerebral artery along the lateral aspect of the midbrain, and the BV ranged in diameter from 1 to 5 mm. The BV drained into the vein of Galen in all but two specimens. The mean distances from the tentorial edge to the BV at the anterior, middle, and posterior borders of the lateral midbrain were 11, 1 3, and 4 mm, respectively. No statistically significant differences were found when comparing left and right sides or male and female specimens., Conclusions: The authors hope that these data will help the neurosurgeon operating near the BV to avoid injury to this important structure.

There is minimal information in the literature regarding the tectorial membrane. Further, information in the literature regarding the anatomy and function of this structure is often contradictory. We performed the current study to elucidate further this structure's detailed anatomy, function, and histology. Thirteen adult cadavers underwent dissection of their tectorial membranes and detailed observations and measurements were made of them. Ranges of motion of the craniocervical junction were performed before and after transection of this structure. Histological analysis was performed on all membranes. The tectorial membrane was found to attach much more superiorly than previously described and was found to be firmly adherent to the cranial base and body of the axis but not to the posterior aspect of the odontoid process. The mean thickness of this membrane was found to be 1 mm. Flexion of the head made the tectorial membrane fully taut at 15 degrees and extension made it fully taut at 20 degrees; however, there was a buckling effect (redundant tectorial membrane) noted at the level of the odontoid process in extension. With the alar and transverse ligaments cut and with flexion of the head, the middle portion of this membrane was stretched over the odontoid process, thus acting as a "hammock" that inhibited the odontoid process from moving posteriorly. The tectorial membrane did not limit cervical flexion per se but rather helped to insure that the odontoid process did not impinge into the cervical canal. Lateral flexion was not found to be limited by this structure. Histologically, parallel collagen fibers with spindle-shaped fibrocytes were observed within this membrane and near its attachment to the posterior axis, the collagen fibers were noted to be more homogenous with larger non-spindled fibrocytes. At the cranial attachment of the tectorial membrane, multiple calcified areas were noted that interdigitated with the underlying bone. Also near this cephalic bony attachment, there was an increase in the number of elastic fibers, which were found running parallel with the surrounding Type III collagen fibers. The tectorial membrane was found to attach much more superiorly than previously described. We would propose that the tectorial membrane provides for a second line of defense, preventing the odontoid process from compressing the spinal cord and by doing so, secondarily limits movement of the craniocervical juncture. This hypothesis is strengthened by the finding of many elastic fibers in the tectorial membrane. To our knowledge, our study is the first to perform a detailed histological analysis of the tectorial membrane. We hope that these data are useful to the clinician who investigates this ligament of the craniocervical region.

Although surgical procedures are often performed over the posterior head and neck, surgical landmarks for avoiding the cutaneous nerves in this region are surprisingly lacking in the literature. Twelve adult cadaveric specimens underwent dissection of the cutaneous nerves overlying the posterior head and neck, and mensuration was made between these structures and easily identifiable surrounding bony landmarks. All specimens were found to have a third occipital nerve (TON), lesser occipital nerve (LON), and greater occipital nerve (GON), and we found that the TON was, on average, 3 mm lateral to the external occipital protuberance (EOP). Small branches were found to cross the midline and communicate with the contralateral TON inferior to the EOP in the majority of sides. The mean diameter of the main TON trunk was 1.3 mm. This trunk became subcutaneous at a mean of 6 cm inferior to the EOP. The GON was found to lie at a mean distance of 4 cm lateral to the EOP. On all but three sides, a small medial branch was found that ran medially from the GON to the TON approximately 1 cm superior to a horizontal line drawn through the EOP. The GON was found to pierce the semispinalis capitis muscle on average 2 cm superior to the intermastoid line. The mean diameter of the GON was 3.5 mm. The GON was found to branch into medial and lateral branches on average 0.5 cm superior to the EOP. The LON was found to branch into a medial and lateral component at approximately the midpoint between a horizontal line drawn through the EOP and the intermastoid line. The main LON trunk was found on average 7 cm lateral to the EOP. In specimens with a mastoid branch of the great auricular nerve (GAN), this branch was found at a mean of 9 cm lateral to the EOP. The main trunk of this branch of the GAN was found to lie on average 1 cm superior to the mastoid tip. Easily identifiable bony landmarks for identification of the cutaneous nerves over the posterior head and neck can aid the surgeon in more precisely identifying these structures and avoiding complications. Although the occipital nerves were found to freely communicate with one another, avoiding the main nerve trunks could lessen postoperative or postprocedural morbidity. Moreover, clinicians who need to localize the occipital nerves for the treatment of occipital neuralgia could do so more reliably with better external landmarks.

Introduction: Stability of the atlantooccipital joint is of vital importance. The ligaments of this region, for the most part, have been thoroughly investigated, except for the lateral atlantooccipital ligament (LAO), which is not described in most modern texts., Materials and Methods: The authors examined 20 adult cadaveric specimens to observe the morphology of the LAO., Results: All specimens were found to have an LAO, bilaterally, immediately posterior to the rectus capitis lateralis muscle with a fiber direction more or less opposite to this muscle. The LAO was found in intimate contact with the vertebral artery posteriorly and with the contents of the jugular foramen anteriorly. In all specimens, the origin of this ligament was from the anterolateral aspect of the transverse process of the atlas and the insertion onto the jugular process of the occipital bone. The fibers of the LAO had a mean angle of 26 degrees from the midline. The mean length and width of this ligament was 2.2 and 0.5 cm, respectively. The mean thickness of the LAO was 2 mm. The average tensile strength of this band was 37.5 degrees N. The LAO remained lax with flexion and extension of the craniocervical junction. With contralateral lateral flexion of the craniocervical junction, the LAO became fully taut at a mean of 8 degrees . Partial, but never complete, tautness was observed with rotation of the occipital on the atlas bilaterally. Following sectioning of the LAO, approximately an additional 3 degrees -5 degrees of contralateral lateral flexion was observed., Conclusions: The LAO is a constant anatomical structure of the craniocervical junction that might be of concern to the clinician. This ligament inhibits lateral flexion of the atlantooccipital joint and its disruption appears to add to instability at this articulation.

Don Manuel Louise Antonio de Gimbernat y Arbós, Spanish anatomist and surgeon, was one of the pioneers during the "age of dissection" (late eighteenth century). A bright young mind, Gimbernat was confident and audacious, which allowed him to become a recognized surgeon with a famed reputation that influenced his colleagues internationally. The Spaniard was most widely recognized for his advancements in the treatment of strangulated femoral hernias, and the lacunar ligament was named "Gimbernat's ligament" in his honor. In 1793, he published Nuevo Método de operar en la Hernia Crural dedicated to King Charles IV, which was translated into English by Thomas Beddoes 2 years later. Gimbernat's daring procedures helped improve safety and efficiency of hernia surgery. A person of great determination, he was known as a brilliant, meticulous, and creative man who exemplified the importance of surgeons. His devoted study of anatomy, especially of inguinal anatomy, allowed him to devise a legendary surgical technique in repairing femoral hernias, influencing renowned surgeons of his time and thereafter.

Manipulation of the cisternal segment of cranial nerves is often performed by the neurosurgeon. To date, attempts at quantifying the forces necessary to disrupt these nerves in situ, to our knowledge, has not been performed. The present study seeks to further elucidate the forces necessary to disrupt the cranial nerves while within the subarachnoid space. The cisternal segments of cranial nerves II through XII were exposed in six unfixed cadavers, all less than 6 hr postmortem. Forces to failure were then measured. Mean forces necessary to disrupt nerves for left sides in increasing order were found for cranial nerves IX, VII, IV, X, XII, III, VIII, XI, VI, V, and II, respectively. Mean forces for right-sided cranial nerves in increasing order were found for cranial nerves IX, VII, IV, X, XII, VIII, V, VI, XI, III, and II, respectively. Overall, cranial nerves requiring the least amount of force prior to failure included cranial nerves IV, VII, and IX. Those requiring the highest amount of force included cranial nerves II, V, VI, and XI. There was an approximately ten-fold difference between the least and greatest forces required to failure. Cranial nerve III was found to require significantly (P < 0.05) greater forces to failure for right versus left sides. To date, the neurosurgeon has had no experimentally derived data from humans for the in situ forces necessary to disrupt the cisternal segment of cranial nerves II through XII. We found that cranial nerve IX consistently took the least amount of force until its failure and cranial nerve II took the greatest. Other cranial nerves that took relatively small amount of force prior to failure included cranial nerves IV and VII. Although in vivo damage can occur prior to failure of a cranial nerve, our data may serve to provide a rough estimation for the maximal amount of tension that can be applied to a cranial nerve that is manipulated while within its cistern.

There is a paucity of information in the literature regarding the mendosal suture. Furthermore, reports of the closure of this presumed suture of childhood are variable. This study seeks to establish the presence or absence of this structure in the adult. Fifty adult skulls were evaluated for the presence or absence of the mendosal suture. Sixteen percent of specimens were found to have a mendosal suture. Six specimens were found to have these sutures bilaterally, and two had sutures on the right side only. Most sutures were linear in nature. The mendosal suture approximated the superior nuchal line in all specimens and more or less traveled medial and perpendicular to the lambdoidal suture. The length of these sutures ranged from 0.8 to 1.4 cm (1.1 cm). Our hopes are that these data will prove useful to both the anatomist and clinicians, so that, when present, misinterpretation of the mendosal suture will be avoided.

The sphenoid ridge (posterior aspect of the lesser wings) is encountered in many intracranial procedures. Increased knowledge of its morphology and relationships is, therefore, of importance to the neurosurgeon and clinician who appreciate imaging of this anatomical region. We have quantitated this part of the sphenoid bone in dry human skulls (35) and made cadaveric (15) measurements between its parts and surrounding neuroanatomical structures in all three cranial fossae. The length of the left and right lesser wings was on average 4.2 and 4 cm, respectively. The mean widths of this bony part at its midline, midpoint, and lateral point (crista alaris) were 1.5 cm, 2.0 cm, and 2 mm, respectively. From the crista alaris the mean distances to the crista galli, V3 at its exit through the foramen ovale, entrance of the occulomotor nerve into the cavernous sinus, middle meningeal artery at its emergence from the foramen spinosum, and the facial and vestibulocochlear nerves at the internal auditory meatus were 4.9, 4.5, 5, 4.7, and 6.1 cm, respectively. From the midpoint of the lesser wing, the mean distances to the crista galli, V3 at its exit through the foramen ovale, entrance of the occulomotor nerve into the cavernous sinus, middle meningeal artery at its emergence from the foramen spinosum, and the facial and vestibulocochlear nerves at the internal auditory meatus were 4.2, 2.9, 3, 3.4, and 4.7 cm, respectively. From the anterior clinoid process of the lesser wing, the mean distances to the crista galli, V3 at its exit through the foramen ovale, entrance of the oculomotor nerve into the cavernous sinus, middle meningeal artery at its emergence from the foramen spinosum, and the facial and vestibulocochlear nerves at the internal auditory meatus were 4.3, 2.8, 1, 3.3, and 4.1 cm, respectively. Additional measurements between the parts of the sphenoid ridge and surrounding anatomical structures may assist the surgeon who operates in this region or the clinician who view imaging of this anatomy.

Objective: There is minimal detailed information regarding the sphenoparietal venous sinus found in the extant medical literature. Furthermore, there is controversy in the literature regarding drainage of the Sylvian vein into this sinus. The sphenoparietal sinus can potentially be encountered with cranial base approaches near the lesser wing of the sphenoid bone and may be found as one surgically traverses the superior orbital fissure., Methods: To further elucidate the anatomy of this structure, we injected this intracranial venous sinus with blue latex in 15 adult cadavers (30 sides) via cannulation of the cavernous sinus near the posterior part of the oculomotor trigone. Observations and measurements of this and nearby structures were then made., Results: A left and right sphenoparietal sinus were found in all specimens and had a mean diameter of 2.5 mm for left sides and 3 mm for right sides. No statistical difference was noted between sides or sexes (P > 0.05). This structure generally began at the lateral tip of the lesser wing of the sphenoid bone and ended in the cavernous sinus near the passage of the ophthalmic nerve. In seven left sides and eight right sides, no discernible connection with the middle meningeal veins was noted. This sinus was found to have a connection with the Sylvian vein in all but one side. One sinus did not drain into the cavernous sinus but rather into the veins of the foramen rotundum. Ten specimens were noted to have previously undocumented temporal veins from the anterior temporal tip that drained into the sphenoparietal sinus., Conclusion: We think that these data will aid the clinician in the diagnosis of the pathology of this region and decrease morbidity that may follow manipulation of this venous sinus.

The split spinal cord is a rare congenital malformation. We report the rare finding of a split cord malformation in a young girl. Further evaluation of this anomaly revealed a Type I split cord malformation (midline bony septation), with no other concomitant pathological entities. Various hypotheses have been made regarding the embryology of this unusual form of spinal dysraphism, and these are reviewed along with the common clinical manifestations of this intriguing pathological entity.

We have previously shown that left-sided vagus nerve stimulation results in cessation of induced spinal cord seizures. To test our hypothesis that right-sided vagus nerve stimulation will also abort seizure activity, we have initiated seizures in the spinal cord and then performed right-sided vagus nerve stimulation in an animal model. Four pigs were anesthetized and placed in the lateral position and a small laminectomy performed in the lumbar region. Topical penicillin, a known epileptogenic drug to the cerebral cortex and spinal cord, was next applied to the dorsal surface of the exposed cord. With the exception of the control animal, once seizure activity was discernible via motor convulsion or increased electrical activity, the right vagus nerve previously isolated in the neck was stimulated. Following multiple stimulations of the vagus nerve and with seizure activity confirmed, the cord was transected in the midthoracic region and vagus nerve stimulation performed. Right-sided vagus nerve stimulation resulted in cessation of spinal cord seizure activity in all animals. Transection of the spinal cord superior to the site of seizure induction resulted in the ineffectiveness of vagus nerve stimulation in causing cessation of seizure activity in all study animals. As with left-sided vagus nerve stimulation, right-sided vagus nerve stimulation results in cessation of induced spinal cord seizures. Additionally, the effects of right-sided vagus nerve stimulation on induced spinal cord seizures involve descending spinal pathways. These data may aid in the development of alternative mechanisms for electrical stimulation for patients with medically intractable seizures and add to our knowledge regarding the mechanism for seizure cessation following peripheral nerve stimulation.

Object: New information regarding nerve branches of the brachial plexus can be useful to the surgeon performing neurotization procedures following patient injury. Nerves in the vicinity of the axillae have been commonly used for neural grafting procedures, with the exception of the lower subscapular nerve (LSN)., Methods: The authors dissected and measured the LSN in 47 upper extremities (left and right sides) obtained in 27 adult cadavers, and determined distances between the LSN and surrounding nerves to help quantify it for possible use in neurotization procedures. The mean diameter of the LSN was 2.3 mm. The mean length of the LSN from its origin at the posterior cord until it branched to the subscapularis muscle was 3.5 cm, and the mean distance from this branch until its termination in the teres major muscle was 6 cm. Therefore, the mean length of the entire LSN from the posterior cord to the teres major was 9.5 cm. When the LSN was mobilized to explore its possible use in neurotization, it reached the entrance site of the musculocutaneous nerve into the coracobrachialis muscle in all but three sides and was within 1.5 cm from this point in these three. In the other specimens, the mean length of the LSN distal to this site of the musculocutaneous nerve was 2 cm. The mobilized LSN reached the axillary nerve trunk as it entered the quadrangular space in all specimens. The mean length of the LSN distal to this point on the axillary nerve was 2.5 cm. Furthermore, on all but one side the LSN was found within the confines of an anatomical triangle previously described by the authors., Conclusions: The authors hope that these data will prove useful to the surgeon for both identifying the LSN and planning for potential neurotization procedures of the brachial plexus.

Object: The authors describe a technique in which the cervical portion of the vagus nerve is exposed during procedures such as neuroma resection or, more commonly, during the placement of a vagus nerve stimulator., Methods: To test their hypothesis that a posterolateral approach to the vagus nerve may be feasible and efficacious, the authors performed dissection of the left-sided vagus nerve in 13 adult cadavers. The carotid sheath was exposed via the posterior cervical triangle, and the vagus nerve was identified posterolaterally. Measurements were made of the length of available nerve, and the anatomical approach was documented. As part of a comparison study regarding the available length of nerve, the authors exposed the left vagus nerve in five additional adult cadavers via a standard anterior approach to the carotid sheath, and compared the results obtained with each technique. A mean length of 12 cm of the vagus nerve was isolated when using the posterior approach to the carotid sheath, whereas a mean length of 11 cm of the nerve was documented when using the anterior approach. With the aforementioned posterior approach, no obvious injury occurred to the vagus nerve or other local neurovascular structures such as the spinal accessory nerve., Conclusions: Evaluation of the findings obtained in the present cadaveric study showed that a posterior approach to the vagus nerve is feasible. The technique for posterior exposure of the carotid sheath may prove useful in surgical exposures of the vagus nerve when a standard anterior method is not possible.

Current anatomical texts describe only two tendinous origins of the rectus femoris muscle. The authors identified one older reference in which a third head of the rectus femoris muscle was briefly described. In order to confirm the existence of this head, 48 adult cadavers (96 sides) underwent detailed dissection of the proximal attachments of the rectus femoris muscle. Of these sides 83% were found to harbour a recognised third head of the rectus femoris muscle. This additional head was found to attach deeply to the iliofemoral ligament and superficially with the tendon of the gluteus minimus muscle as it attached into the femur. This tendon attached to the anterior aspect of the greater trochanter in an inferolateral direction compared to the straight head. The mean length and width of the third head was 2 cm and 4 cm, respectively. The mean thickness was found to be 3 mm. Most commonly this third head was bilaterally absent or bilaterally present. However, 4.2% were found only on left sides and 5.2% were found only on right sides. The angle created between the reflected and third heads was approximately 60 degrees. Two sides (both left sides with one female and one male specimen) were found to have third heads that were bilaminar. These bilaminar third heads had a distinct layer attaching to the underlying iliofemoral ligament and a superficial layer blending with the gluteus minimus tendon to insert onto the greater trochanter. Although the function of such an attachment is speculative, the clinician may wish to consider this structure in the interpretation of imaging or in surgical procedures in this region, as in our study it was present on the majority of sides.

Variations of the triceps brachii muscle are apparently rare. We report an additional attachment site of the medial head of the triceps brachii found on the left side of a male cadaver. This head originated from the posterior aspect of the surgical neck of the humerus. Clinicians diagnosing or treating patients with weakness or pain of the posterior arm should consider anomalous muscles in this region that may result in neurovascular compression., (Copyright 2006 Wiley-Liss, Inc.)

We report a male cadaver found to have his right intermediate branch of the supraclavicular nerve piercing the clavicle. No other anomalies were found in this specimen. Following a review of the literature, it appears that symptoms related to this finding are rare but do occur most commonly involving the intermediate branch of the supraclavicular nerve. Symptoms may be alleviated with surgical decompression of the entrapped nerve. Although rare, the clinician should include entrapment of the supraclavicular nerve within the clavicle in their differential diagnosis of shoulder pain., (Copyright 2006 Wiley-Liss, Inc.)

We report an unusual finding in an adult male cadaver. During the routine dissection of the posterior abdominal wall as part of an anatomy course at our institution, an anomalous muscle was noted. This muscle originated from the transverse process of the left L3 vertebrae and the medial aspect of the quadratus lumborum. We believe this muscle to represent a variety of the psoas quartus that, to our knowledge, has only been described once before in the extant medical literature. The presence of a psoas quartus muscle may contribute to femoral nerve compression. The clinician may wish to consider this rare muscular anomaly in patients with symptoms of femoral nerve compression in which no other clear etiology is found. Furthermore, clinicians who image the posterior abdominal wall should be aware of this potential anomaly when interpreting the anatomy of this region., (Copyright 2006 Wiley-Liss, Inc.)

We report a 13-year-old female who presented to an outside emergency room following blunt trauma to the head. As part of her evaluation, an unenhanced CT of the face and radiographs of the cervical spine were performed. She was referred to our clinic with "abnormal" imaging. Radiographs revealed dysmorphic cervical spine and ventral clefting of the vertebral bodies from C7-T2. A subsequent MRI was obtained that demonstrated a large spinal cord mass. MRI demonstrated an unenhanced intramedullary mass of the cervicothoracic spinal cord measuring approximately 1.5 cm in greatest axial diameter. Surgical exploration of her intraspinal mass revealed a neurenteric cyst. Spinal neurenteric cysts are categorized in the spectra of occult spinal dysraphism and most likely arise from incomplete separation of the developing notochord and foregut in the embryo. We discuss potential etiologies for the formation of such cysts. The clinician should consider neurenteric cysts in their differential diagnosis of patients with spinal dysraphism and/or intraspinal masses., (Copyright 2006 Wiley-Liss, Inc.)

We report a case of the rare tensor fascia suralis muscle. This muscle was found during the routine dissection of the lower extremity in an adult male cadaver. No other anomalies were noted in this specimen. The innervation of this muscle was via the tibial component of the sciatic nerve. Although seemingly rare, the tensor fascia suralis muscle may be considered by the clinician in the differential diagnosis of masses over the posterior lower extremity.

The biceps femoris is the most lateral component of the so-called hamstring muscles. Classically, this muscle's insertion into the head of the fibula has been described but further details of its anatomy have not been universally appreciated. Additional insertions into the crural fascia and tibia have been described. We dissected 56 cadavers paying especially close attention to the insertion of the biceps femoris muscle. The tendon of this muscle was found to have both medial and lateral slips each with an anterior and posterior component. Further, we found an attachment not only into the lateral condyle of the femur but also the popliteus tendon and arcuate popliteal ligament. Our study has found that the tendon of insertion of the biceps femoris muscle is more complex than described previously and suggests that this tendon may be far more important in knee stability based on the multiple attachment sites found. We hypothesize that there may be a synergistic effect between the biceps femoris and the popliteus muscles based on our findings of an additional attachment of the biceps femoris tendon into the popliteus tendon. This study provides new detailed nomenclature for the description of the tendon of insertion of the biceps femoris muscle and indicates that the current description of the insertion of the tendon of the biceps femoris muscle should be revised. The clinician must have a thorough understanding of this anatomy before correct therapeutic maneuvers can be implemented.

There is a paucity of information in the literature regarding the quadrate ligament and the information that does exist is extremely conflicting. We dissected 30 cadavers (60 sides) to determine the morphology and function of this enigmatic ligament. A quadrate ligament (thickening of the elbow joint capsule) was found in all specimens. In all specimens this band was distinct from the circumferential fibres of the annular ligament. The length, width, and thickness of the quadrate ligament were found to be 11 mm, 8 mm, and 1 mm respectively. This ligament not only aided in securing the neck of the radius to the ulna but also resisted excessive supination and, to a lesser degree, pronation of the forearm. Following transection of the quadrate ligament, the head of the radius was secured to the ulna considerably less firmly and supination and pronation increased by 10 to 20 degrees and 5 to 8 degrees respectively. The quadrate ligament contributes to proximal radioulnar stability, limits the "spin" of this joint, and should be considered in manipulation, surgery, or imaging of the proximal forearm.

LITTLE IS KNOWN of the early physician/anatomist Vidius Vidius (Guido Guidi). Anatomic structures named after Vidius include the Vidian nerve, artery, and canal and are well known to neurosurgeons. His anatomic treatise was printed under the title Vidi Vidii: Florentini de anatome corporis humani libri VII in a posthumous edition (1626). We report what is known regarding this historical figure of both early anatomy and medicine.

Early examples of intentional human cranial deformation predate written history. Intentional cranial deformation as an extreme has seemingly not persisted into this century. However, mild forms of this manipulation are still practiced by various groups worldwide. Accidental cranial deformation or mild forms of intentional cranial deformation may be encountered by the clinician or anatomist. We review the literature regarding intentional manipulation of the human cranium.

Object: There is a paucity of information in the neurosurgical literature regarding the surgical anatomy surrounding the posterior interosseous nerve (PIN). The goal of the current study was to provide easily recognizable superficial bone landmarks for identification of the PIN., Methods: Thirty-four cadaveric upper extremities obtained from adults were subjected to dissection of the PINs, and measurements were made between this nerve and surrounding superficial bone landmarks. In all specimens the main radial trunk was found to branch into its superficial branch and PIN at the level of the lateral epicondyle of the humerus. Proximally, the PIN was best identified following dissection between the brachioradialis and extensor carpi radialis longus and brevis muscles. At its exit site from the supinator muscle, the PIN was best identified after retraction between the extensor carpi radialis longus and brevis and extensor digitorum communis muscles. This site was a mean distance of 6 cm distal to the lateral epicondyle of the humerus. No compression of the PIN by the tendon of origin of the extensor carpi radialis brevis muscle was seen. One specimen was found to have a proximally split PIN that provided a previously undefined articular branch to the elbow joint. The mean diameter of the PIN proximal to the supinator muscle was 4.5 mm. The leash of Henry crossed the PIN in all but one specimen and was found at a mean distance of 5 cm inferior to the lateral epicondyle. The PIN exited the distal edge of the supinator muscle at a mean distance of 12 cm distal to the lateral epicondyle of the humerus. Here the mean diameter of the PIN was 4 mm. The exit site from the distal edge of the supinator was found to be at a mean distance of 18 cm proximal to the styloid process of the ulna. This exit site for the PIN was best identified following dissection between the extensor carpi radialis longus and brevis and extensor digitorum communis muscles. The distal articular branch of the PIN was found to have a mean length of 13 cm and the proximal portion of this terminal segment was located at a mean distance of 7.5 cm proximal to the Lister tubercle., Conclusions: The addition of more anatomical landmarks can help the neurosurgeon to be more precise in identifying the PIN and in avoiding complications during surgery in this region.

Object: In neurotization procedures, donor nerves--either whole or in part-with relatively pure motor function can be carefully chosen to provide the optimal nearby motor input with as little donor site morbidity as possible. In this context, the ulnar nerve branches to the forearm muscles are relatively dispensable; however, quantitation of and landmarks for these branches are lacking in the literature., Methods: The ulnar branches to the flexor carpi ulnaris (FCU) and flexor digitorum profundus (FDP) muscles in 20 upper extremities obtained in adult cadaveric specimens were dissected and quantified. In the forearm, a mean of four nerve branches led to the FCU and FDP muscles. A mean of 3.4 branches led to the FCU muscle; of these, one to three were medial branches and zero to two were lateral. Medial branches to the FCU muscle originated a mean of 2.7 cm inferior to the medial epicondyle. Lateral branches to the FCU muscle originated at a mean of 3.3 cm inferior to the medial epicondyle. The mean length of the medial branches was 3.2 cm, whereas the mean length of the lateral branches was 3.3 cm. All nerves had a single trunk for the FDP muscle, and in all specimens this branch was located deep to the main ulnar nerve trunk, originating from the ulnar nerve a mean of 2.7 cm inferior to the medial epicondyle. These branches had a mean length of 5.6 cm. The mean diameter of all medial and lateral branches to the FCU muscle was 1 mm, and the mean diameter of the branch to the FDP muscle was 2.1 mm. All branches to both the FCU and FDP muscles arose from the ulnar nerve, over its first approximately 5 cm from the level of the medial epicondyle. Additionally, all branches could be easily lengthened by gentle proximal dissection from the main ulnar nerve., Conclusions: Ulnar branches to the forearm can be easily localized and used for neurotization procedures. The branch to the FDP muscle had the greatest diameter and longest length, easily reaching the median nerve and posterior interosseous nerve via a transinterosseous membrane tunneling procedure. Furthermore, this branch could be teased away from the main ulnar nerve trunk and made to reach the distal branches of the musculocutaneous nerve in the arm.

There is scant detailed information regarding the tabatière anatomique (anatomical snuff box) in the literature. The authors dissected this area in 15 adult cadavers (30 sides) and made measurements and observations of this region. We found that the average mean width and length of this geometric area was 4 cm and 6 cm, respectively. Although the dimensions of the tabatière anatomique tended to be larger among male specimens this trend did not reach statistical significance (P > 0.05). There was no statistical difference between left and right sides. The majority (70%) of specimens was noted to have connections between the cephalic vein and the vena comitantes of the radial artery within the tabatière anatomique. Five specimens were noted to have a muscular branch to the abductor pollicis brevis muscle arising from the dorsalis pollicis artery in the tabatière anatomique. The dorsalis pollicis artery was found to originate in the tabatière anatomique in all specimens. One right-sided specimen was noted to have an intraosseous branch of the radial artery that entered the styloid process of the radius. A well-formed collection of fat was noted between the styloid process and base of the first metacarpal in all specimens. This fat pad completely covered the radial artery in the majority of specimens and had loose connections to both the first and second dorsal compartments. The branches of the superficial branch of the radial nerve always originated distal to the tendon of the EPB muscle. These data may prove useful to the surgeon or clinician who operates or examines this interesting anatomical area.

Object: There are scant data regarding the anterior interosseous nerve (AIN) in the neurosurgical literature. In the current study the authors attempt to provide easily identifiable superficial osseous landmarks for the identification of the AIN., Methods: The AIN in 20 upper extremities obtained in adult cadaveric specimens was dissected and quantified. Measurements were obtained between the nerve and surrounding superficial osseous landmarks. The AIN originated from the median nerve at mean distances of 5.4 cm distal to the medial epicondyle of the humerus and 21 cm proximal to the ulnar styloid process. The distance from the origin of the AIN to its branch leading to the flexor pollicis longus muscle and to the point it travels deep to the pronator quadratus (PQ) muscle measured a mean 4 and 14.4 cm, respectively. The mean distance from the AIN branch leading to the flexor pollicis longus muscle to the proximal PQ muscle was 12.1 cm, and the mean distance between this branch and the ulnar styloid process was 7.2 cm. The mean diameter of the AIN was 1.6 mm at the midforearm., Conclusions: Additional landmarks for identification of the AIN can aid the neurosurgeon in more precisely isolating this nerve and avoiding complications. Furthermore, after quantitation of this nerve, the AIN branches can be easily used for neurotization of the median and ulnar nerves, and with the aid of a transinterosseous membrane tunneling technique, passed to the posterior interosseous nerve.