Continuation of the ascending cervical artery as the occipital artery in man.

We report an elderly male cadaver with unilateral anomalous continuation of the ascending cervical artery as the occipital artery. The ascending cervical artery was enlarged from its origin and supplied segmental branches through the intervertebral foramina. At the upper cervical spine, the ascending cervical artery continued as the occipital artery providing the branches normally seen stemming from this artery. No other vascular anomalies were noted in this specimen. This anatomical curiosity should be kept in mind by the clinician or academic who may manipulate this anatomical area.

Femoral head of the rectus femoris muscle.

Variability of the muscles of the anterior thigh is minimal. After review of the extant medical literature, we believe this to be the first reported case of a femoral head of the left and right rectus femoris muscles. In addition to this anomaly, our anatomic specimen demonstrated an accessory head of the right brachialis muscle and the quadratus plantae muscles inserted into the tendons of both the flexor hallucis longus and flexor digitorum longus. In clinical practice, knowledge of the possibility of an anomalous accessory femoral head of the rectus femoris muscle in clinical practice would be useful for those who might palpate this unusual muscle or encounter it surgically.

Fenestration of the superior medullary velum as treatment for a trapped fourth ventricle: a feasibility study.

We developed a novel approach for fenestration of the trapped fourth ventricle utilizing the superior medullary velum (valve of Vieussens). Trapped fourth ventricles, which are seen often in the pediatric hydrocephalic population, are troublesome entities surgically. A right burr hole was carried out in 10 adult cadavers with no gross intracranial pathology and the superior medullary velum was fenestrated to the quadrigeminal cistern with the aid of an endoscope. This technique was carried out easily in all cadaveric specimens. With endoscopy, no vascular insult was appreciated either before or after fenestration of the superior medullary velum. These preliminary findings demonstrate that fenestration of the superior medullary velum may provide a good alternative to the present therapy of shunting trapped fourth ventricles, a therapy wrought with complications.

Eyebrow incision with supraorbital trephination for endoscopic corpus callosotomy: a feasibility study.

OBJECTIVE: We describe a novel technique for the partial bisection of the corpus callosum in order to increase the minimally invasiveness of this procedure. METHODS: Brow incisions with midline trephinations were performed in six adult cadavers. An endoscope was next introduced and used to transect approximately the anterior two-thirds of the corpus callosum. RESULTS: No complications such as injury to the superior sagittal sinus or anterior cerebral artery were encountered in any of our cadaveric specimens. The corpus callosum was easily transected in each specimen. CONCLUSION: As a feasibility study, we believe this technique could provide a less invasive mechanism for patients who require corpus callosotomy and will minimize much of the morbidity associated with the traditional methods of sectioning the corpus callosum.

Anatomic landmarks for the cervical portion of the thoracic duct.

OBJECTIVE: Avoidance of injury to the thoracic duct during neurosurgical procedures involving the cervical region depends on a working knowledge of its location. This study evaluates superficial anatomic landmarks for the cervical portion of the thoracic duct that may be encountered in neurosurgery of the neck. METHODS: Fifteen dissections of human cadavers were performed to study the relationship between the proximal thoracic duct and superficial landmarks (e.g., the cricoid cartilage and sternal notch of the manubrium). RESULTS: The cervical portion of the thoracic duct was found to be approximated by a roughly 4.4-cm(2) region in the left supraclavicular area beginning approximately 2.0 cm lateral to the midline and 3.5 cm superior to the sternal notch, extending superiorly to a point roughly 3.5 cm from the midline and 2.5 cm inferior to the cricoid cartilage, and terminating within the venous system at a point approximately 4.5 cm lateral to the midline and 3.0 cm superior to the sternal notch. CONCLUSION: Through an increased appreciation for its location, injury to the thoracic duct may be minimized.

Anomalous traversement of the suprascapular artery through the suprascapular notch: a possible mechanism for undiagnosed shoulder pain?

BACKGROUND: The literature is deficient in studies aimed at quantifying the occurrence of a suprascapular artery traversing the suprascapular notch with the suprascapular nerve. MATERIAL/METHODS: We have performed a cadaveric study using 60 adult specimens (120 sides). Thirty-eight specimens were male and twenty-two were female. RESULTS: Our findings conclude that in this group, the suprascapular artery travels with the suprascapular nerve through the suprascapular notch in 2.5% of specimen sides. Both specimens in whom this occurred were male. CONCLUSIONS: We hypothesize that this anatomic anomaly may also constitute a possible unrecognized mechanism in which shoulder pain is generated. Further studies focused at various races and the presence of this peculiarity are now needed to confirm our findings. In addition, unexplained chronic shoulder pain may be explored with vascular studies aimed at identifying the course of the suprascapular artery.

Intracranial anatomic asymmetry in situs inversus totalis.

Situs inversus is a rare condition in which the position of the thoracic and the abdominal viscera are exchanged from the left to the right sides. A possible inversion of normal dominant intracranial anatomy, has however, rarely been discussed. We examine here the gross anatomy of an elderly cadaveric female for a possible "situs inversus" of the intracranial contents. This study has found that many structures commonly dominant on one side in the intracranial compartment were reversed in this specimen. These findings support the concept that a reversal of more commonly found intracranial anatomy may occur in situs inversus totalis, and this should alert the clinician performing invasive procedures in this population. These data will also hopefully provide further insight into possible mechanisms that contribute to situs inversus totalis.

Accessory obturator nerves with bilateral pseudoganglia in man.

During the routine dissection of the pelvis and anterior thigh of an adult female cadaver, accessory obturator nerves were found bilaterally with pseudoganglia. In addition, each accessory obturator nerve rejoined the anterior division of the normally placed obturator nerves after traveling superficial to the pubic bones. Histological sections revealed primarily normal nerve with no neuronal cell bodies within these focal areas of enlargement. No inflammatory response was noted in these histologically normal peripheral nerve structures. Further gross anatomy including other peripheral nerves was found to be normal. Peripheral nerve "ganglia" are found in the literature with little focus on histology. Our case report represents to our knowledge, the first report of a pseudoganglion in association with an accessory obturator nerve.

Absence of the falx cerebelli in a Chiari II malformation.

After a review of the literature, we found no descriptions of the falx cerebelli in the Chiari II population. Other dural partitions in this group have been well-described. The aim of our study was to radiologically and at autopsy search for the falx cerebelli in this population. We retrospectively analyzed 50 CTs and 50 MRIs in children with a known Chiari II malformation, searching for either the falx cerebelli or internal occipital crest, the bony attachment for the falx cerebelli; these structures were also investigated in two patients at autopsy. We were unable to observe the falx cerebelli or internal occipital crest on any of the radiologic images or at autopsy. We theorize that a "crowded" posterior cranial fossa in these patients inhibits the development of the falx cerebelli and internal occipital crest.

Superficial surgical landmarks for the frontal sinus.

OBJECT: There is a lack of reports in the literature that contain descriptions of superficial anatomical landmarks for the identification of the internally located frontal sinus. Neurosurgeons must often enter the cranium through the frontal bone and knowledge of the frontal sinus is essential to minimize complications. METHODS: Seventy adult cadaveric frontal sinuses were evaluated. Measurements included both the lateral and superior extent of the frontal sinus in reference to a midpupillary line, and the superior extent of the frontal sinus from the nasion. Frontal sinuses were found bilaterally in all specimens. The mean height of the frontal sinus superior to the nasion was 2.8 cm. In 71.4% and 74.3% of specimens the lateral extent of the frontal sinus was found to be medial to the left and right midpupillary line, respectively. Distances superior to a plane drawn through the supraorbital ridges at a midpupillary line included a mean of 2.5 mm for the left side and 1.8 mm for the right side. CONCLUSIONS: Of 70 sinuses, none extended more than 5 mm lateral to a midpupillary line. At this same midpupillary line and at a plane drawn through the supraorbital ridges, the frontal sinus was never higher than 12 mm. Finally, in the midline the frontal sinus never reached more than 4 cm above the nasion. These measurements will assist surgeons who must manipulate the frontal bone.

Blood supply of the human cervical sympathetic chain and ganglia.

OBJECTIVE: Cadaveric studies of the blood supply to the human cervical sympathetic chain and ganglia are lacking in the English literature. This study seeks to elucidate the gross blood supply of the cervical sympathetic chain so as to avoid surgical disruption of these vessels and thus decrease the risk of vascular insufficieny and subsequent dysfunction of thoracolumbar autonomic outflow to the head and neck. METHODS: Twelve (24 sides) human cadavers (8 male and 4 female) were dissected and their brachiocephalic veins, internal carotid arteries, and vertebral arteries cannulated. Red and blue latex was injected into the arteries and veins respectively. Dissection of the neck was carefully performed and the blood supply of the cervical sympathetic chain identified. RESULTS: The primary arterial supply to the sympathetic chain and ganglia were from superior to inferior the ascending pharyngeal, ascending cervical, thyrocervical trunk, and supreme intercostal arteries. The primary venous drainage of these structures was primarily by direct posterior branches into the internal jugular vein. In addition, we have found an area at the junction of the lower two-thirds and upper one-third of the neck, which is deficient in blood supply (both arterial and venous). CONCLUSIONS: Although sympathetic injury is a rare consequence of cervical operations, the current data should be useful to the surgeon who operates in the cervical region so as to avoid potential complications from disruption of the primary blood supply of the cervical sympathetic chain and ganglia. Also, future techniques of selective iatrogenic disruption of the blood supply to portions of these structures e.g. stellate ganglion may be helpful in treating entities such as hyperhydrosis.