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Biomedical subjects

Robert G Louis

Publications and source records attributed to Robert G Louis.

At least 19 recordsLinked to original sources
PubMed2007

False tendons: an endoscopic cadaveric approach.

False tendons (FTs) have been extensively described and recognized by gross anatomic studies. However, in the clinical setting the recognition of FTs is limited to the use of echocardiography. We examined 200 formalin fixed adult hearts, with gross dissections. In addition, 90 of these specimens were also examined with ultrasonographic and endoscopic techniques. Gross examination was able to identify FTs in 128 (62%) specimens. The total number of FTs observed, was 248 and was classified into five types according to their location. In Type I (92, 37.1%) the FT was located between the posteromedial papillary muscle and the ventricular septum. In Type II (55, 22.1%) the FT was located between the two papillary muscles. Type III (41, 16.5%) was classified as an FT between the anterolateral papillary muscle and the ventricular septum. The FT in Type IV (31, 12.5%) was observed to connect between the ventricular septum and the free wall and lastly in Type V (29, 11.6%) the FTs were found to be weblike with three or more points of insertion. When using all three techniques (n = 90), gross dissection and endoscopy were able to identify FTs in 62.2% of specimens while echocardiographic imaging was only able to identify FTs in 27.7% of specimens. Of the 114 FTs detected grossly and endoscopically, echocardiography was only able to identify 46 (40.3%). Therefore, the overall sensitivity of echocardiography for detecting left ventricular FTs was only 40.3%, compared to 100% for endoscopy. Based upon the ability or lack thereof of echocardiography to detect certain topographical patterns, we have created a small series of subtypes for the FTs. Histologically, in 30% of the FTs, conduction tissue fiber was observed to be present, which may implicate them in the appearance of arrhythmias.

Adult↗
PubMed2007

Branches of the petrous and cavernous segments of the internal carotid artery.

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.

Carotid Artery, Internal↗
PubMed2006

Superior phrenic artery: an anatomic study.

The majority of anatomical textbooks offer very little information concerning the anatomy and distribution of the superior phrenic artery (SPA). However, in the last decade, a number of reports have appeared with reference to the transcatheter arterial chemoembolization of the collateral arterial supply of hepatic carcinoma (HC). Considering the potential role of the SPA as a source of collateral blood supply to HC, the aim of this study was to identify the origin and distribution of the SPA. One hundred formalin-fixed adult cadavers with no evidence of significant gross diaphragmatic pathology were examined. The right SPA originated from the aorta (R1) in 42%, as a branch of the proximal segment of the 10th intercostal artery (R2) in 33%, and as a branch of the distal segment of the 10th intercostal artery (R3) in 25%, of the specimens. The left SPA originated from the aorta (L1) in 51%, from proximal segment of the left 10th intercostal artery (L2) in 40%, and from the distal segment of the left 10th intercostal artery (L3) in 9%, of the specimens. In types R1, R2, L1 and L2 the SPA terminated, after a short course, within the medial and posterosuperior surfaces of the thoracic diaphragm and diaphragmatic crura. Conversely, in types R3 and L3 the lateral origin of the SPAs confined the ultimate distribution of the vessels to the posterior surface of the diaphragm. These findings could provide a better understanding of the anatomy and distribution of the arterial supply of the diaphragm and the potential involvement of the right SPA as an extrahepatic collateral artery developed in HC.

Aged↗
PubMed2006

Multiple variations of the hepatobiliary vasculature including double cystic arteries, accessory left hepatic artery and hepatosplenic trunk: a case report.

Anatomical variations in the origins and branching patterns of the hepatobiliary arterial system may be encountered during both conventional surgical and laparoscopic cholecystectomy. We report a rare case of double cystic arteries arising from both the right hepatic artery and the proximal part of the posterior superior pancreaticoduodenal artery. Additional variations consisting of an accessory left hepatic artery arising from a left gastric which in turn arose from the descending aorta superior to the origin of the celiac trunk and a small left hepatic artery arising from the hepatic proper artery were also noted. The celiac trunk bifurcated into the splenic artery and the common hepatic artery forming a hepatosplenic or lienohepatic trunk. The possible clinical implications are discussed.

Cadaver↗
PubMed2006

Pseudoaneurysm of the membranous septum, case report and review of the literature.

Pseudoaneurysm (dissecting aneurysm) of the membranous septum is a rare occasion. Clinically, aneurysms and pseudoaneurysms not only have the potential to reduce ventricular size, but also can be further complicated by rupture of the aneurysm and by promoting tricuspid insufficiency, aortic valve prolapse, ventricular outflow tract obstruction, and bacterial endocarditis. We describe a case in which a pseudoaneurysm of the membranous septum was identified protruding into the left outflow tract.

Aged↗
PubMed2006

A detailed observation of variations of the facial artery, with emphasis on the superior labial artery.

The reconstruction of lip defects through the use of the Abbe flap and other lip flap procedures involves surgical manipulation of one of the major branches of the facial artery, specifically the superior labial artery (SLA). We examined 284 hemifaces derived from 142 formalin fixed cadavers. Observations regarding the distribution patterns of the facial artery were recognized and categorized into five Types, labeled "A" through "E". Type A (135, 47.5%): facial artery bifurcates into SLA and lateral nasal (the latter gives off inferior and superior alar and ends as angular); Type B (110, 38.7%): similar to Type A, except lateral nasal terminates as superior alar (angular artery is absent); Type C (24, 8.4%): facial artery terminates as SLA; Type D (11, 3.8%): angular artery arises directly from facial arterial trunk rather than as the termination of lateral nasal, with the facial artery ending as superior alar; Type E (4, 1.4%): facial artery terminates as a rudimentary twig without providing any significant branches. Furthermore, we were able to categorize variations within each Type. Sub-Type variations were examined in Types A through C (A: 1-7; B: 1-4; C: 1-3). Our aim was to equip both the anatomist and surgeon with a more thorough understanding of the vasculature of the face, as well as to enable plastic surgeons to have a more confident approach to reconstructive procedures in this region.

Adult↗
PubMed2006

Gross anatomical, CT and MRI analyses of the buccal fat pad with special emphasis on volumetric variations.

The use of the buccal fat pad (BFP) has increased in popularity in recent years because of its reliability, ease of harvest, and low complication rate during oral and maxillofacial procedures. The aim of this study was to evaluate the volumetric variations of the BFP with a CT and MRI, as well as the thickness, weight and volume with conventional methods. We have examined the BFP from 80 formalin fixed adult cadavers (mean age 59) derived from both males (45) and females (35). In addition, we also examined 20 cadaveric BFPs using MR and CT imaging. Digital image analysis software was used to measure the volumetric distribution and to characterize the morphology of BFP. The BFP can be divided into three lobes (anterior, intermediate, and posterior) and has four extensions (buccal, pterygoid, pterygopalatine, and temporal). The BFP is fixed by six ligaments, to the maxilla, posterior zygoma, inner and outer rim of infraorbital fissure, temporalis tendon, and buccinator membrane. The mean volume in males was 10.2 ml and ranged 7.8-11.2 ml, while in females the mean volume was 8.9 ml and ranged 7.2-10.8 ml. Additionally, the mean thickness was 6 mm, with a mean weight of 9.7 g. These facts may be important when considering the use of the BFP in reconstruction, particularly whether the correct volume has been removed from each side in aesthetic, oral, or maxillofacial procedures.

Adipose Tissue↗
PubMed2006

Anatomical and surgical considerations of the sacrotuberous ligament and its relevance in pudendal nerve entrapment syndrome.

In view of the paucity of literature, this study was undertaken to reappraise the gross anatomy of the sacrotuberous ligament (STL), with the objective of providing an accurate anatomical basis for clinical conditions involving the STL. We studied the gross anatomy of the STL in 50 formalin fixed cadavers (100 sides) during the period of 2004-2005. All specimens exhibited an STL with a ligamentous part and (87%) of specimens exhibited a membranous (falciform) segment, which extended towards the ischioanal fossa. The variations of the falciform extensions were classified into three types. In Type I (69%), the falciform process extended towards and along the ischial ramus to terminate at the obturator fascia. In Type II (108%), the falciform process extended along the ischial ramus, fused with the obturator fascia and continued towards the ischioanal fossa. In addition, the medial border of the falciform process descended to fuse with the anococcygeal ligament, forming a continuous membrane. Lastly, in Type III (13%), the falciform process of the STL was absent. The above mentioned data could have an important implication to the understanding of the relationship between the pudendal nerve and the sacrotuberous ligament and their relevance to pudendal nerve entrapment syndrome.

Aged↗
PubMed2006

The gross anatomy of the extrathoracic course of the intercostobrachial nerve.

Recent reports emphasize the importance of preserving the intercostobrachial nerve (ICBN) during surgical procedures (i.e., mastectomy, axillary clearance). However, a limited number of scientific reports explore the surgical anatomy of this nerve. We dissected 100 adult human formalin-fixed cadavers (200 axillae). In all the cadavers the ICBN was present with variant contributions from intercostal nerves T1, T2, T3, and T4. The arrangements of the ICBN were typed as I through VIII. The components of Type I (45% or 90 of our specimens) included a branch to the posterior antebrachial cutaneous nerve, a branch to the anterior and lateral parts of the axilla, a branch to the medial side of the arm, and a branch to the medial antebrachial cutaneous nerve. Type II (25%) describes the ICBN arising from T2 and giving off a branch to the brachial plexus. In Type III (10%), lateral cutaneous branches of T2 and T3 fuse as a common trunk and then split immediately after exiting the intercostal space to form an ICBN. In type IV (5%), T2 and T3 join distally to form an ICBN that ends as its terminal branches. Type V (5%): T3 joins T2 from the same intercostal space proximally, with Type VI (3%) showing a very proximal branching of the sensory terminal nerves. Type VII (5%) displayed a contribution from T3 and a branch to the brachial plexus with multiple terminating branches. A contribution from T3 and T4 and a branch to the brachial plexus with multiple branches of termination comprised Type VIII (2%).

Aged↗
PubMed2006

Anatomical examination of the recurrent artery of Heubner.

There is considerable inconsistency in the description of the origins, dimensions, and course of the recurrent artery of Heubner (RAH). The RAH frequently supplies parts of the basal ganglia and the anterior limb of the internal capsule and can be damaged with improper clip placement during repair of aneurysms near the anterior communicating artery. Thus, further elaboration of the anatomical descriptions of the RAH is necessary. The gross anatomy of the RAH was studied in 69 human brain hemispheres. RAH was found as a single vessel in 53 hemispheres (77%), as double arteries in 12 hemispheres (17%), and was absent in 4 hemispheres (6%). The origin of the RAH was from the junction of the anterior cerebral artery and anterior communicating artery in 48 (62.3%) hemispheres, from the proximal A2 segment of the anterior cerebral artery in 18 (23.3%) hemispheres and from the A1 segment in 11 (14.3%) hemispheres. The diameters of the artery ranged from 0.2 to 1.3 mm with a mean of 0.8 mm, while the length ranged from 0.9 to 3.8 cm with a mean of 2.4 cm. The above data may provide important information to neurosurgeons operating in this area, as well as to neuroanatomists teaching the vascular supply of the brain.

Anterior Cerebral Artery↗
PubMed2006

An unusual innervation of pectoralis minor and major muscles from a branch of the intercostobrachial nerve.

Variations of the branching pattern of the intercostobrachial nerve have been known to complicate dissection during mastectomy and other procedures involving the axilla. We present a unilateral case of a 73-year-old Caucasian female, in which the intercostobrachial nerve gives rise to an additional medial pectoral branch, which partially innervates the pectoralis minor muscle, as well as the abdominal head of pectoralis major muscle. Clinical consequences of such a variation may include motor losses, in addition to the commonly reported sensory losses, resulting from accidental or intentional dissection of the intercostobranchial nerve.

Aged↗
PubMed2006

A case of an accessory brachialis muscle.

Functionally, the brachialis muscle serves a critical role as the primary flexor of the arm at the elbow. However, few reports exist in the literature, which describe variations of this muscle. We present a case of an accessory brachialis muscle (AcBr), found during routine dissection at Harvard Medical School during 2003. The AcBr originated medially from the mid-shaft of the humerus and the medial intermuscular septum. During its course medially, toward the elbow, the AcBr crossed both the brachial artery and the median nerve. The distal tendon split to surround the median nerve before inserting into the common tendon of the antebrachial flexor compartment muscles. Embryological origins and clinical considerations including median nerve entrapment are considered.

Aged↗
PubMed2006

The surgical anatomy of the ansa pectoralis.

Detailed anatomical knowledge of the pectoral nerves is of clinical importance in surgeries as diverse as limb neurotization, mastectomy, orthopedic procedures and operations related to trauma. The brachial plexus of 200 cadavers were examined in an attempt to clarify the normal origins, courses and variations of the nerves with special emphasis on the ansa pectoralis (AP). In 75% the MPN arose from the anterior division of the inferior trunk of the brachial plexus and in 25% it arose from the medial cord. In 40% of specimens, the LPN arose from a single contributing nerve (anterior division of the superior trunk, 11%; anterior division of the middle trunk 18%; lateral cord, 11%). In the remaining 60% of specimens, the LPN arose from the fusion of two rootlets derived variably from the anterior divisions of the superior and middle trunks and the lateral cord. A single AP was found to be present bilaterally in 200 (100%) of the specimens. Classification of the AP was based upon its origin from the upper or lower rootlet of the LPN, the LPN itself, or from the deep branch of the LPN. AP-1 (42%) arose from the deep branch of the LPN; AP-2 (28%) arose directly from the LPN; AP-3 (25%), arose from the lower rootlets of the LPN and rarely, the AP arose from the upper rootlet of the LPN and crossed posterior to the lower rootlet to communicate with the MPN (AP-4, 5%). Irrespective of the aforementioned types, the AP was found to be present, crossing the second segment of the axillary artery in 90% of the specimens. These results could prove useful during the preoperative planning of neurotization and other surgical procedures involving the axilla.

Aged↗
PubMed2006

Surgical anatomy of the accessory phrenic nerve.

BACKGROUND: Reports place the frequency of phrenic nerve injury after cardiac operations between 10% and 85%, emphasizing the importance of an accurate anatomic description of the diaphragm's innervating nerves to reduce iatrogenic injury, length of hospitalization, and associated costs. The aim of our study was to explore the anatomic variations of the accessory phrenic nerve and relate these findings to phrenic nerve injury. METHODS: Eighty adult formalin-fixed cadavers were dissected, resulting in 160 nerve specimens. Fifty nerve specimens were also examined laparoscopically with findings later confirmed through gross dissection. All nerves contributing to the phrenic nerve after crossing the anterior scalene were considered to be accessory phrenic nerves. RESULTS: The phrenic nerve was present in all specimens, and 99 (61.8%) also had an accessory phrenic nerve. The accessory phrenic nerve arose from the nerve to subclavius in 60 specimens (60.6%), ansa cervicalis in 12 (12.1%), and nerve to sternohyoid in 7 (7%). The accessory phrenic nerve joined with the phrenic nerve in the thorax anterior to the subclavian vein in 45 (45.5%) specimens and posterior in 17 (22.2%). A phrenic-accessory phrenic nerve loop was found around the subclavian vein in 45 (35 on the right, 10 on the left) specimens and around the internal thoracic artery in 38 (31 on the right, 7 on the left). CONCLUSIONS: To reduce injuries to the diaphragm, the presence of an accessory phrenic nerve should be considered before mobilization and skeletonization of the internal thoracic artery above the second rib.

Adult↗
PubMed2006

The relationship of myocardial bridges to coronary artery dominance in the adult human heart.

Myocardial bridging is recognized as an anatomical variation of the human coronary circulation in which an epicardial artery lies in the myocardium for part of its course. Thus, the vessel is 'bridged' by myocardium. The anterior interventricular branch of the left coronary artery has been reported as the most common site of myocardial bridges but other locations have been reported. The purpose of this study was to provide more definitive information on the vessels with myocardial bridges, the length and depth of the bridged segment, and the relationship between the presence of bridges and coronary dominance. Two hundred formalin-fixed human hearts were examined. Myocardial bridges were found in 69 (34.5%) of the hearts with a total of 81 bridges. One bridge was found in 59 of these hearts and multiple bridges were observed in ten (eight with double bridges and two with triple bridges). Bridges were most often found over the anterior interventricular artery (35 hearts). Bridges were also found over the diagonal branch of the left coronary artery (14), over the left marginal branch (five) and over the inferior interventricular branch of the left coronary artery (six). Bridges were also found over the right coronary artery (15 hearts), over the right marginal branch (four) and over the inferior interventricular branch of the right coronary artery (two). The presence of bridges appeared to be related to coronary dominance, especially in the left coronary circulation. Forty-six (66.6%) of the hearts with bridges were left dominant. Forty-two of these had bridges over the left coronary circulation and four over the right coronary circulation. Seventeen hearts (24.6%) were right dominant. Eleven of these had bridges over the right coronary circulation and six over the left coronary circulation. The remaining six hearts were co-dominant with four having bridges over the left coronary circulation and two over the right coronary circulation. The mean length of the bridges was 31 mm and the mean depth was 12 mm. The possible clinical implications of myocardial bridging may vary from protection against atherosclerosis to systolic vessel compression and resultant myocardial ischaemia.

Adult↗