Puboperineales: muscular boundaries of the male urogenital hiatus in 3D from magnetic resonance imaging.

PURPOSE: The aims of this report are 1) to extend our previous two-dimensional magnetic resonance imaging study to create a three-dimensional image of the pelvic floor, including the puboperinealis, the most anteromedial component of the levator ani; 2) to clarify the historical controversy about this particular component of the levator ani; and 3) to present clinical implications of this muscle with respect to urinary continence and radical prostatectomy. MATERIALS AND METHODS: We reused the axial magnetic resonance imaging series from 1 of 15 men in a previous series. Analyze AVWTM allowed creation of three-dimensional images. Further, a movie clip of all three-dimensional images was developed and placed at the manuscript-dedicated Web site: http://www.mayo. edu/ppmovie/pp.html. RESULTS: Our three-dimensional images show how the puboperinealis portion of the levator ani flanks the urethra as it courses from the pubis to its insertion in the perineal body. CONCLUSIONS: The puboperinealis corresponds to muscles previously designated as the levator prostatae, Wilson's muscle, pubourethralis, and levator urethrae, among others. The images suggest that the puboperinealis is the muscle most responsible for the quick stop phenomenon of urination in the male. Our study supports the suggestion that weakening of the puboperinealis by transection, traction injury, or denervation may affect urinary continence after radical prostatectomy.

Quantification of active caspase 3 in apoptotic cells.

We describe an enzyme-linked immunosorbent assay (ELISA) for quantifying relative amounts of active caspase 3 in apoptotic cells. Covalent modification of caspase 3 active sites with a biotinylated inhibitor differentiates active from latent caspases. Capture on an ELISA plate with an antibody specific for caspase 3 makes the assay specific for caspase 3. Detection is with horseradish peroxidase (HRP)-conjugated streptavidin that binds to the biotinylated inhibitor covalently bound to caspase 3. Using the assay we detected 6.6 ng active caspase 3 per 10(6) apoptotic staurosporine-treated Jurkat cells. Specificity of the assay for caspase 3 was demonstrated by lack of signal with purified caspases 2, 7, 8, and 10 that were modified by a biotinylated inhibitor. Specificity was also demonstrated by lack of signal with apoptotic MCF-7 cells which do not express caspase 3. The ability to discriminate between active and latent caspase 3 was shown by Western blotting with HRP-streptavidin and anti-caspase 3. Although latent caspase 3 was captured it was not covalently modified with the biotinylated inhibitor. The basic principle of using a covalent inhibitor to identify active enzymes and an antibody to differentiate between enzymes with similar activities has potential for quantifying active members of many classes of enzymes.

Transversalis fascia: historical aspects and its place in contemporary inguinal herniorrhaphy.

Since the introduction of the term "fascia transversalis" by Sir Ashley Cooper in 1840, this thin layer of tissue has been discovered, denied, and redefined. The transversalis fascia was originally described as a bilaminar membrane. Although most subsequent descriptions do not reflect this analysis, some authors, especially in the surgical literature, believe that a posterior lamina of the transversalis fascia exists. Others believe that the posterior lamina of the transversalis fascia is, in fact, part of the preperitoneal fascia. The usefulness of the transversalis fascia and its derivatives or analogues; e.g., the crura of the deep inguinal ring, have also been extensively discussed. The aim of this paper is to provide a brief survey of the historical literature concerning the transversalis fascia and a discussion of some of the contemporary views on its morphology and significance in current laparoscopic hernia repair.

Anatomy of the ulnar nerve at the elbow: potential relationship of acute ulnar neuropathy to gender differences.

Men develop perioperative ulnar neuropathies more frequently than women. To determine the role of anatomical gender differences in the development of these neuropathies, we performed several studies of the anatomy of the ulnar nerve, cubital tunnel, and elbow region. These studies included detailed dissection of male and female embalmed and unembalmed cadavers, ultrasound measurements of the tissue layers at the elbow, and measurement of various dimensions of the coronoid process of the ulna in multiple skeletal sets. No gross anatomical differences were found between genders regarding the course of the ulnar nerve through the upper limb. However, there was a strikingly larger (2-19 times greater) fat content on the medial aspect of the elbow in women compared to men, and the tubercle of the coronoid process was approximately 1.5 times larger in men (P < or = .002, rank sum test). Our finding suggest that the tubercle of the coronoid process is a likely area for external compression-induced ischemia of the ulnar nerve because the nerve and its arterial supply (the posterior ulnar recurrent artery) are covered at the tubercle only by skin, subcutaneous fat, and a very thin aponeurosis of the flexor carpi ulnaris. Importantly, this tubercle is larger and the nerve and blood vessels passing by it are less protected by subcutaneous fat in men than in women. These two anatomical differences between men and women may contribute to the increased frequency of perioperative ulnar neuropathy induced by external pressure at the medial aspect of the elbow in men.

Infraclavicular brachial plexus block: parasagittal anatomy important to the coracoid technique.

UNLABELLED: Infraclavicular brachial plexus block is a technique well suited to prolonged continuous catheter use. We used a coracoid approach to this block to create an easily understood technique. We reviewed the magnetic resonance images of the brachial plexus from 20 male and 20 female patients. Using scout films, the parasagittal section 2 cm medial to the coracoid process was identified. Along this oblique section, we located a point approximately 2 cm caudad to the coracoid process on the skin of the anterior chest wall. From this point, we determined simulated needle direction to contact the neurovascular bundle and measured depth. At the skin entry site, the direct posterior insertion of a needle will make contact with the cords of the brachial plexus where they surround the second part of the axillary artery in all images. The mean (range) distance (depth along the needle shaft) from the skin to the anterior wall of the axillary artery was 4.24 +/- 1.49 cm (2.25-7.75 cm) in men and 4.01 +/- 1.29 cm (2.25-6.5 cm) in women. Hopefully, this study will facilitate the use of this block. IMPLICATIONS: We sought a consistent, palpable landmark for facilitation of the infraclavicular brachial plexus block. We used magnetic resonance images of the brachial plexus to determine the depth and needle orientation needed to contact the brachial plexus. Hopefully, this study will facilitate the use of this block.

Anomalous thymic branch of the right common carotid artery.

A previously unreported anomalous thymic artery that branched from the anterior aspect of right common carotid artery approximately 1 cm above bifurcation of the brachiocephalic artery was found during routine dissection. It traveled inferiorly through a plexus of inferior thyroid veins for 6 cm in front of the brachiocephalic artery and crossed the anterior surface of the trachea where it divided into two branches that supplied the right and left lobes of the thymus. The development and blood supply of the thymus and their clinical anatomy are reviewed.

Anatomy of radical prostatectomy as defined by magnetic resonance imaging.

PURPOSE: We examined and defined anatomical structures relevant to radical prostatectomy using magnetic resonance imaging. MATERIALS AND METHODS: Before radical prostatectomy, 15 men underwent high-resolution magnetic resonance imaging studies of their pelvic floors (fast spin echo, T2 weighting of 3- to 4-mm. contiguous or overlapping slices) in axial, coronal, and sagittal planes. RESULTS: Pubovesical ligaments, rather than the commonly reported puboprostatic ligaments, were observed attaching the bladder-prostate unit to the pubis. We suggest that the part of the urethra that extends from the apex of the prostate to the bulb of the penis, which is surrounded by the striated sphincter, should be termed the sphincteric urethra rather than the membranous urethra. Further, we found no evidence that supports the traditional concept of a urogenital diaphragm. The lower part of the striated urethral sphincter was flanked on its sides by the anterior recesses of the ischioanal fossae. The portion of the levator ani, which we have termed the puboanalis sling, flanked the apex of the prostate. The most anteromedial portion of this sling inserts into the perineal body and should be termed the puboperinealis. The terminal part of the gastrointestinal tract (the part continued beyond the levator ani) should be termed the anal canal, not the rectum, as used frequently in the urologic literature. Therefore, the initial plane of dissection in radical perineal prostatectomy passes along the anterior portion of the anal canal, not the rectum. CONCLUSION: We used magnetic resonance imaging to study male pelvic floor and perineal anatomy without the artifact of dissection. This study allowed us to devise a more precise nomenclature with respect to radical prostatectomy and, in so doing, to provide a better understanding of both the retropubic and the perineal operations.

Defining the cross-sectional anatomy important to interscalene brachial plexus block with magnetic resonance imaging.

BACKGROUND AND OBJECTIVES: Interscalene brachial plexus block is a useful technique to provide anesthesia and analgesia for the shoulder and proximal upper extremity. The initial needle direction at the interscalene groove has been described as being "perpendicular to the skin in every plane" (1). A cross-sectional (axial) approach may offer a more easily conceptualized directed needle placement. The purpose of this study is to define the cross-sectional anatomy and idealized needle angles important to interscalene brachial plexus block. METHODS: Following IRB approval, 50 patients were studied. Cross-sectional volume coil T1-weighted magnetic resonance images (MRI) were obtained from 50 patients undergoing cervical region imaging for other reasons. At the interscalene groove, a simulated needle path to contact the ventral rami or trunks of the brachial plexus was approximated at the level of C6 or C6-C7 interspace. The angle of this needle path intersecting the sagittal plane was recorded for each patient. RESULTS: The mean angle of the simulated needle path relative to sagittal plane was determined to be 61.1 +/- 6.1 degrees (range, 50-78 degrees). In 13 of 50 (26%) MRI scans, the cervical nerve roots were not visualized at the level of C6 and were measured at the C6-C7 level. CONCLUSIONS: These findings suggest initial needle placement at the interscalene groove should be angled less perpendicularly relative to the sagittal plane than is often observed. A cross-sectional approach enables more practical visualization of initial needle placement. A more accurate initial needle placement may minimize the number of needle passes necessary to contact the nerve roots, thereby more efficiently obtaining a successful block.

Catching up.

The medical school I (S.M.) attended did not require dissection of a cadaver to fulfill the requirements of the anatomy curriculum. I had "learned" human anatomy through lectures, text books, and an atlas, but did no dissection. Although it was difficult doing anatomy that way, I passed basic science exams with high marks and did well on the board exams (NBME). I graduated from medical school with distinction and thought I was well prepared for residency. To my surprise, dissection of the orbit and periorbital regions and cranial cavity were included in my ophthalmology residency and were to pose a challenge for me. I requested the aid of a medical school anatomist to help me face this challenge. Not only did I learn the art of dissection, I gained considerable knowledge in anatomy (much of it clinically relevant), acquired better skill with surgical instruments and enhanced my logical and critical thinking ability. This viewpoint is based upon a diary I kept during my dissection experience.

A special anatomic preparation for teaching central venous catheterization.

Catheterization of the subclavian and internal jugular veins is a commonly performed procedure for monitoring the hemodynamic, respiratory, and fluid status of patients as well as for delivery of special potent drugs and nutritive solutions. In inexperienced hands, this procedure can carry significant morbidity. A comprehensive central line placement teaching program has been developed at our institution centered upon an anatomy and catheterization skills workshop. A dedicated anatomic specimen has been prepared to emphasize key anatomical concepts about the subclavian and internal jugular veins. A design with easily reflectable flaps allows quick and simple visualization of needle position after supervised cannulation attempts. Workshop preparation and teaching sessions benefit from close collaboration between anatomists and clinicians. This should help standardize residents' exposure to central venous cannulation techniques and ensure basic procedure skills prior to actual cannulation in patients.

The effect of removing the true dental follicle on premolar eruption in the dog.

Eruption is a highly localized process during which the bone resorption and formation that occur on opposite sides of the tooth are dependent upon the surrounding soft tissues, the true dental follicle externally and the enamel organ internally. To examine the ability of the enamel organ to cause eruption the external layer (dental follicle) was removed just prior to and up to 4 weeks before eruption in 13 mandibular premolars in dogs and eruption followed clinically, radiographically and histologically. None of the teeth without dental follicles erupted but three teeth from which the follicle was separated then replaced did erupt. These data indicate that the enamel organ without the dental follicle cannot support tooth eruption and provide indirect evidence for the central role of the dental follicle, alone or in combination with the enamel organ, in eruption.

Supraclavicular nerve block: anatomic analysis of a method to prevent pneumothorax.

Supraclavicular nerve blocks are technically easy to perform, but may be associated with pneumothorax. The objective of this study is to define the parasagittal anatomy important to our modified technique of supraclavicular nerve block designed to decrease the incidence of pneumothorax and to determine whether this technique is anatomically sound. Two cadaver specimens were studied. One embalmed specimen was dissected to establish the relationship of the brachial plexus to our modified needle entry site. The neck and upper thorax of an unembalmed cadaver were frozen, and parasagittal serial sections were made to establish the relationship of the brachial plexus to surface features and the chest cavity. Additionally, 12 volunteers underwent magnetic resonance (MR) imaging and anatomic measurements of their supraclavicular anatomy important to our modified block. MR imaging showed that in no instance using our modified technique was the lung contacted by the simulated needle before entering either the subclavian artery or contacting the brachial plexus. Our technique has been used in more than 110 patients without pneumothorax. The combination of our cadaver and magnetic resonance data suggests that our plumb-bob technique of supraclavicular nerve block is anatomically sound and may minimize the development of pneumothorax during supraclavicular block.