Wesley W. Parke

The variant blood supply to the descending colon, rectosigmoid and rectum based on 400 dissections. Its importance in regional resections

The variant blood supply to the descending colon, rectosigmoid and rectum based on 400 dissections. Its importance in regional resections: A review of medical literature Nicholas Michels;Padmanabhan Siddharth;Paul Kornblith;Wesley Parke; Diseases of the Colon & Rectum

Malformations of the liver: Some prenatal and postnatal developmental aspects

The discovery of a large articulated lobe weighing 165.4 g dependent from the anterior margin of the left liver lobe in a 93‐year‐old female culminated two decades of observation of anomalous liver conditions in anatomic cadavers. When this data was compared with the information previously recorded from a series of 52 perinatal livers, remarkable discrepancies between the adult and perinatal incidences of various anomalous manifestations were noted. Ectopic accessory lobes were very rare in our adult series as well as in the groups reported in literature reviews. However, they were a relatively common occurrence in the perinatal cases, as were also gallbladder bridges of hepatic tissue, hypertrophic papillary lobes, and marked accessory fissures. In contradistinction, marginal accessory lobes were not noticed in any of the perinatal livers. Because the liver undergoes considerable postnatal reformation, it was concluded that most ectopic lobes, gallbladder bridges, hypertrophic caudate lobe extensions, and accessory fissures disappear during postnatal remodeling, whereas marginal accessory lobes may result from retention of the original perinatal boundaries of the anterior liver margins.

Avascular necrosis of the hamate: a case report with reference to the hamate blood supply.

Avascular necrosis of the hamate bone has not previously been reported. In this case the proximal fragment of the fractured hamate underwent avascular necrosis and prolonged healing. In an attempt to explain this sequela, angiography of the cadaver carpus followed by dissection of intact wrists and a study of enzyme-cleaned hamates showed that their wedge-shaped proximal segments were mostly enveloped by a distal extension of the midcarpal joint cavity and thus totally dependent on intraosseous nutrition. Consequently, the segment is at risk when a fracture line transects the body proximal to the base of the wedge. Clinically, this condition resulted in persistent discomfort and limitations of motion. A postinjury bone scan of the wrist indicated avascular changes in the proximal third of the hamate, and a delayed union was followed by later revascularization and a more normal scan image.

The Vascular Pattern of the Human Dorsal Root Ganglion and Its Probable Bearing on a Compartment Syndrome

Study Design. A descriptive anatomic investigation of the vasculature of the dorsal root ganglions. Objectives. To determine whether the blood supply of the various spinal ganglions is sufficiently consistent to derive a “generic” description and illustration that would be applicable to all spinal levels, and to ascertain whether this vascular pattern is inherently predisposed to the development of a closed compartment syndrome. Summary of Background Data. The few previous descriptions of spinal ganglionic vasculature do not include photographic evidence showing uniformity in the arterial distribution plan at all ganglionic levels. The venous drainage, although verbally reconstructed from microscopic sections, lacks any indication of its probable role in the etiology of a compartment syndrome. Methods. Three perinatal cadavers received latex/India ink injections, and their removed radiculomedullary systems were cleared, transilluminated, and macroscopically photographed. Paravertebral sections were grossly removed from the spines of two adult anatomic cadavers and received retrograde venous injections of a fine suspension of barium sulfate. The intervertebral foraminal tissues were then dissected from the bone, and radiographs of them were made. For comparative reference, a nerve root/ganglion complex of a rabbit was arterially injected with a more dilute preparation of the latex/India ink suspension. Results. Macroscopic photographs of perinatal dorsal root ganglions showed that the pattern of the intraganglionic arterial distribution was sufficiently consistent to allow a graphic rendering and labeling of a “generic” ganglion. The series of incomplete retrograde venous injections adequately indicated the pressure labile location of a periganglionic venous plexus. Conclusions. The common development, structure, and function of the human dorsal root ganglions have resulted in the evolution of a uniform nutritional vascular pattern that can be conceptualized in a single visual image. Its plan of a primarily internal arterialization with a superficial venous drainage renders it vulnerable to the ischemic conditions consequent on external pressures and/or internal edematous swelling. This vascular arrangement may contribute to a propensity for the ganglion to develop a compartment syndrome when subjected to compression by periforaminal degenerative or neoplastic space-occupying lesions.

Intimal musculature of the lower anterior spinal artery.

Study Design. This was a descriptive microscopic investigation of the smooth musculature in the human lower anterior spinal artery using anatomic cadaver tissues with supporting data derived from angiographic studies of neonatal cadavers. Objective. To determine the extent and configuration of the intimal musculature in the lower anterior spinal artery and deduce the probable influence it has on the lower spinal cord blood flow, as well as its effects on the axial anastomotic potentials during aortic cross-clamping. Summary of Background Data. The high incidence of ischemic spinal cord injury after aortic cross-clamping has led to many studies of autoregulation of the spinal cord blood flow, but none have identified the probable vascular mechanisms. Methods. Spinal tissue blocs that included the mid-thoracic and thoracolumbar anterior spinal artery, and sections of excised anterior spinal artery were dissected from spinal cords of 16 cadavers, refixed in Bouins solution, paraffin embedded, and microscopically studied in sections processed in Massons tri-chrome stain. A radioangiographic study of barium-perfused spines of neonatal cadavers was used to substantiate histologic observations. Results. The smooth muscle of the tunica media of the lower anterior spinal artery is reinforced by a conspicuous longitudinally disposed layer of intimal muscle. At the junction of the arteria medullaris magna and the anterior spinal artery, this muscle forms intimal cushions that can dramatically alter the luminal diameters of the vessels involved. Conclusion. The described muscular characteristics of the lower anterior spinal artery indicate it has a previously unsuspected capacity to control extrinsic and intrinsic aspects of the lower spinal cord blood flow, a factor that should be considered in clinical and experimental procedures involving spinal cord collateral circulation.

The pial ligaments of the anterior spinal artery and their stretch receptors : a spinal cord distraction-sensing system ?

The pial sheath of the anterior spinal artery displays a system of ligaments that course along the ventral surfaces of the anterior spinal artery and its medullary feeder arteries on the lower half of the spinal cord. Frequently, discrete ligamentous straps extend from these anterior spinal artery ligaments to the sheath of an anterior spinal nerve root to reinforce the general cauda equina pial connections to this system. Microscopy of ligament sections revealed that numerous Golgi-type neurofascicular receptors were oriented longitudinally among the ligament fascicles and associated with well-myelinated nerves. As this type of mechanoreceptor has been known only in association with stretch reflex mediation in the musculoskeletal system, it appeared likely that these anterior spinal artery ligaments and their homologous type of receptors may be implicated in sensing distraction of the thoracolumbar spinal cord and protectively modifying the actions of the involved spinal musculature.

Lumbosacral anterolateral spinal arteries and brief review of “accessory” longitudinal arteries of the spinal cord

The lumbosacral anterolateral spinal arteries (LALSA) were studied in 14 injected lumbosacral spinal cords. Contrary to many previously published opinions, which claimed that virtually all of the formerly described “accessory” longitudinal arteries of the vasa corona, were too inconstant to be of significance, the LALSA in this series were reliably present bilaterally and averaged a length of 8.4 cm. They ran in the acute angles formed by the emergence of the fascicles of the lumbosacral anterior spinal nerve roots and in this position, served as the origin for most of the proximal radicular arteries that supply the cranial half of the motor roots of the cauda equina. A review of the literature and analysis of other accessory longitudinal spinal arteries revealed that two other pairs of accessory spinal vessels, the lateral cervical spinal arteries (LCSA) and the lateral spinal arterial axes (LSA), have a demonstrable functional role and were sufficiently constant, along with the LALSA, to warrant inclusion in detailed descriptions of human spinal cord vasculature. Clin. Anat. 12:171–178, 1999.

Role of Epidural and Radicular Veins in Chronic Back Pain and Radiculopathy

Although the pattern and major components of the human medullary arterial supply were widely known by the end of the nineteenth century, the details of the associated venous circulation were generally ignored. Despite Brechet’s (1) quite accurate description and later depiction of the complexity of the spinal venous system, published in 1835 (Fig.1), the ubiquity and variability of its ramifications evidently discouraged further consideration beyond the comprehension that the veins collectively served as collateral channels to the caval and azygos systems. Another factor that may have contributed to the general disregard of the anatomical particulars of these channels may have been related to their structural delicacy. The thinness and transparency of their walls render them almost invisible during conventional cadaver dissections unless they show postmortem evidence of congestion or are specifically filled with a contrast medium. Clemens (2) noted that these vessels were quite pliable, which permitted considerable distension under collateral load. Thus, the Queckenstedt maneuver, which tests the patency of the spinal subarachnoid space by compression of the jugular or intra-abdominal veins, causes an increase in cerebrospinal fluid (CSF) pressure by an external compression from the expansion of the collaterally loaded epidural plexus. Clemens also postulated that a passive congestion of the spinal cord was prevented by minute valves in the proximal sources of the radicular veins that drain the spinal cord, a unique situation considering that none of the other sinus veins possess valves.

Pulmonary appendix of the short-tailed shrew (Blarina): A unique immunologic organ

The right bronchus of the short‐tailed shrew, Blarina brevicauda, terminates in a nonrespiratory pulmonary appendix (PA) containing two bronchial extensions. The experimentally demonstrated ability of these structures to collect and peristaltically expel aspirated material was initially assumed to be a sufficient reason for their developmental persistance, but as bronchus associated lymphoid tissue (BALT) became a subject of immunologic interest in other species, a possible immunologic role for the concentrations of BALT observed in the shrew PA were investigated. As the BALT of the PA contained many well‐differentiated plasma cells and numerous particle‐containing macrophages, 6‐μ paraffin sections were treated with an immunoperoxidase avidin‐biotin preparation that chromogenically identified alpha chains of IgA in many of the PA plasma cells and their associated luminal secretions. Also, vascular injections revealed that the PA had a complex relationship with anastomotic sinusoids connecting the bronchial and pulmonary circulation systems, and scanning electron microscopy showed that the luminal epithelial surfaces of the PA were virtually identical to the scattered BALT aggregates in the bronchi of other animals. It thus appeared that these unique structures in the shrew are morphologically and topographically suited to receive aspirated antigens that induce secretory IgA production, while possibly providing other humoral and cellular immunologic products to the general circulation. Anat Rec 266:184–191, 2002.