A cadaver study evaluating intraluminal anomalies of the left common iliac vein.

OBJECTIVE: Intraluminal anomalies within the left common iliac vein, characteristic of iliac vein compression syndrome, are thought to result from compression by and pulsation of the overlying right common iliac artery. This cadaver study was designed to expand on the existing literature by surveying and photographing these spurs in addition to exploring whether certain factors, inherent to the cadaver, are associated with spur presence. METHODS: Dissection to expose the aorta, inferior vena cava, and common iliac arteries and veins was performed in 51 cadavers. The spinal level at which the iliac vein confluence occurred was noted. The point at which the right common iliac artery crossed the left common iliac vein was examined for plaque presence. The overlying arterial structures were then transected to expose the venous system. The inferior vena cava was incised to facilitate observation into the mouth and full extent of the left common iliac vein. Spurs were photographed and documented. Statistical analysis was conducted to determine whether sex, body mass index (BMI), plaque presence, or level of the iliac vein confluence are associated with spur presence. RESULTS: Spurs within the left common iliac vein were observed in 16 of 51 cadavers (31.4%). All spurs were located at the point that the right common iliac artery crossed the left common iliac vein. Using1 the classification system established by McMurrich, 67% of spurs (n = 10) were marginal and triangular; 25% (n = 4) were columnar. One marginal, linear spur (6%) and one partially obstructed spur with multiple synechiae (6%) were observed. Among this population, males were 73% less likely to have a spur (odds ratio, 0.269; P = .041). No significant relationship was found between plaque presence and spur presence (odds ratio, 0.933; P = .824) and no significant differences were noted between BMI and spur presence (χ2 = 1.752, P = .625). Last, a significantly greater percent of spurs was found within cadavers with an iliac vein confluence located at the L5/S1 disc space (χ2 = 9.650; P = .002). CONCLUSIONS: Study findings show that spurs are more common when the confluence of the common iliac veins occurs at a lower spinal level. The level of the iliac vein confluence may be important in identifying patients at increased risk of venous disease. The findings also suggest that plaque within the right common iliac artery and BMI display no distinct relationship with spur presence. Further investigation is needed to understand exactly what factors lead to spur formation.

A Cadaveric Evaluation of Hypertrophic Obstructive Cardiomyopathy.

Hypertrophic obstructive cardiomyopathy (HOCM) describes a pathologic state in which the subaortic region of the interventricular septum undergoes significant hypertrophy and fibrosis, resulting in septal bowing into the left ventricle. The reduced left ventricular chamber size and altered cardiac function impair diastolic filling, stroke volume, and cardiac output. This case report evaluates the cardiac tissue of a 36-year-old, formalin-embalmed cadaver affected by HOCM, with the goal of providing a comprehensive overview of the gross and pathologic findings associated with the condition. This donor's heart was found to be larger than average, weighing 510.1 g, which is 52% heavier than the predicted value of 335.6 g for a male of similar stature. The thickness of the interventricular septum, right ventricular free wall, and left ventricular free wall was comparable to other reports of HOCM. However, asymmetrical thickening of the left ventricular walls, which is characteristic of HOCM, was less prominent than expected. Histologic staining of the cadaveric tissue, with hematoxylin and eosin, trichrome, and desmin, further bolstered the diagnosis. Importantly, this also showed that histologic examination of embalmed tissue is effective and diagnostic, even 11 months after embalming. The report herein demonstrates that morphologic and histologic analysis of cadaveric cardiac tissue is sufficient to support a diagnosis of HOCM. To the researchers' knowledge, this is the first case report evaluating HOCM in a cadaver donated for medical education.

Effects of Leg Length, Sex, Laterality, and the Intermediate Femoral Cutaneous Nerve on Infrapatellar Innervation.

Background: An iatrogenic injury to the infrapatellar branch of the saphenous nerve (IPBSN) is a common precipitant of postoperative knee pain and hypoesthesia. Purpose: To locate potential safe zones for incision by observing the patterns and pathway of the IPBSN while examining the relationship of its location to sex, laterality, and leg length. Study Design: Descriptive laboratory study. Methods: A total of 107 extended knees from 55 formalin-embalmed cadaveric specimens were dissected. The nerve was measured from palpable landmarks: the patella at the medial (point A) and lateral (point B) borders of the patellar ligament, the medial border of the patellar ligament at the patellar apex (point C) and tibial plateau (point D), the medial epicondyle (point E), and the anterior border of the medial collateral ligament at the tibial plateau (point F). The safe zone was defined as 2 SDs from the mean. Results: Findings indicated significant correlations between leg length and height (r P = 0.832; P < .001) as well as between leg length and vertical measurements (≥45°) from points A and B to the IPBSN (r P range, 0.193-0.285; P range, .004-.049). Male specimens had a more inferior maximum distance from point A to the intersection of the IPBSN and the medial border of the patellar ligament compared with female specimens (6.17 vs 5.28 cm, respectively; P = .049). Right knees had a more posterior IPBSN from point F compared with left knees (-0.98 vs-0.02 cm, respectively; P = .048). The majority of knees (62.6%; n = 67) had a nerve emerging that penetrated the sartorius muscle. Additionally, 32.7% (n = 35) had redundant innervation, and 25.2% (n = 27) had contribution from the intermediate femoral cutaneous nerve (IFCN). Conclusion: We identified no safe zone. Significant innervation redundancy with a substantial contribution to the infrapatellar area from the IFCN was noted and contributed to the expansion of the danger zone. Clinical Relevance: The location of incision and placement of arthroscopic ports might not be as crucial in postoperative pain management as an appreciation of the variance in infrapatellar innervation. The IFCN is a common contributor. Its damage could explain pain refractory to SN blocks and therefore influence anesthetic and analgesic decisions.

Mapping a Danger Zone of the Dorsal Nerve of the Clitoris: Implications in Female Cosmetic Genital Surgery.

BACKGROUND: The literature regarding the route of the dorsal nerve of the clitoris is sparse and lacks surgical focus. With an increasing number of procedures being performed on the labia, it is important to elucidate the route and note any variation from normal of the nerve. METHODS: Fifty-one cadavers were dissected to yield 97 dorsal nerve of the clitoris samples. Measurements were taken from (1) the dorsal nerve of the clitoris penetration point of the perineal membrane to the urethra, (2) the nerve's penetration point of the perineal membrane to the pubic bone, (3) the angle of the clitoris to the branch point of the dorsal nerve of the clitoris, and (4) the branch point of the nerve to the distalmost point of the glans clitoris. Any anomalous branching patterns of the dorsal nerve of the clitoris were recorded and classified. RESULTS: The means and standard deviations of each measurement were used to create a surgical danger zone. The mean of each measurement was (1) 34.63 mm, (2) 5.74 mm, (3) -3.07 mm, and (4) 30.40 mm, respectively. In addition, six distinct branching patterns were observed, organized, and classified based on the location and number of branches observed. CONCLUSIONS: The dorsal nerve of the clitoris has multiple branching patterns and typically travels along the same course in most women. Further investigation of the course and three-dimensional position of the dorsal nerve of the clitoris is warranted to preserve sexual sensation as the frequency of procedures involving the female pudendum increases.

Anatomic Variations From 120 Mental Nerve Dissections: Lessons for Transoral Thyroidectomy.

BACKGROUND: Transoral endoscopic thyroidectomy vestibular approach (TOETVA) is a promising technique for eliminating a neck incision. A new risk of TOETVA is the potential for injury to the mental nerves during placement of three oral endoscopic ports. A better understanding of the variations in mental nerve anatomy is needed to inform safer TOETVA technique. MATERIALS AND METHODS: We performed 120 dissections of mental nerve branches exiting the mental foramen in 60 human cadavers. Anatomic distances and relationships of the foramen to the midline were evaluated. Mental nerve branching patterns were studied and compared with previously reported classification systems to determine surgical safe zones free of nerve branches. RESULTS: The mean midline-to-mental foramen distance was 29.2 ± 3.3 mm, with high variability across individuals (18.8-36.8 mm). There were differences in this distance between the left and right foramina (29.8 ± 3.2 versus 28.8 ± 3.3 mm, P = 0.03). All mental nerve branches exiting the mental foramen distributed medially. The branching patterns were classified into eight distinct categories, three of which are previously undescribed. One of these novel patterns, occurring in 9.2% of cases, had a dense and wide clustering of branches traveling toward the midline. CONCLUSIONS: The location of the mental foramen and mental nerve branching patterns demonstrate high variability. To avoid mental nerve injury in TOETVA, we identify a safe zone for lateral port placement lateral to the plane of the mental foramen. Placement and extension of the middle port incision should proceed with caution, as clustering of mental nerve branches in this area can frequently be present.

Mapping the genicular arteries to provide a caution zone during knee surgery.

INTRODUCTION: Reports from the current literature show a lack of detail with depictions of the genicular arteries (GA). The intricate anatomy and infrequency of operating in the posterior knee may lead to surgeons being unfamiliar with the anatomy. The goal of this cadaveric study was to quantitatively map the arteries and create a caution zone that can be utilized when preparing and performing surgical procedures involving the knee. MATERIALS AND METHODS: The left knees of 46 cadavers were used. The distance of the GAs were from the joint line (JL) (+, superior to JL; -, inferior to JL) was measured in two locations: popliteal artery (PA) branch point and medial/lateral knee. The angle the artery traveled between these two points in the posterior knee was measured. A caution map was created. RESULTS: The superolateral GA branched from PA at +47.3 mm and traveled superiorly at 57.7° to +52.2 mm at the lateral knee. The superomedial GA branched from PA at +55.2 mm and traveled superiorly at 66.8° to +57.3 mm at the medial knee. The inferolateral GA branched from PA at -0.6 mm. It traveled superiorly at 74.1° or inferiorly at 62.1° to -1.0 mm at the lateral knee. The inferomedial GA branched from the PA at +9.9 mm. It traveled inferiorly at 21.2° to -33 mm at the medial knee. CONCLUSION: The GAs have a predictable pattern of location in the knee. There is a mismatch between medical textbooks and reality regarding arterial depictions. Knowledge regarding where the arteries are located may help reduce vascular complications in patients in the future.

Validity of the Rule of Threes and Anatomical Relationships in the Thoracic Spine.

CONTEXT: The location of the more superficial thoracic spinous processes is used to help osteopathic physicians locate the deeper and more difficult-to-palpate thoracic transverse processes. In 1979, Mitchell et al proposed the thoracic rule of threes to describe the relationship of the spinous processes to the transverse processes in the thoracic spine. This rule is currently taught at osteopathic medical schools. The rule of threes separates the thoracic vertebrae into 3 distinct groups, each with a different relationship between transverse processes and spinous processes. In 2006, Geelhoed et al proposed a new relationship between the spinous processes and transverse processes for all thoracic vertebrae (ie, Geelhoed's rule). OBJECTIVE: To determine which anatomical relationship-the rule of threes or Geelhoed's rule-is most accurate in locating the transverse processes and to define anatomical relationships between thoracic spinous and transverse processes. METHODS: The thoracic spinous and transverse processes of 44 formalin-embalmed human cadavers were dissected, marked, and photographed. Six different measurements per vertebra were made between spinous processes and transverse processes in the thoracic spine. Geelhoed's protocol was used to determine the validity of each rule. The measurements were analyzed for additional relationships between thoracic spinous processes and transverse processes. Group 1 consisted of vertebrae T1 to T3 and T12; group 2 consisted of T4 to T6 and T11; and group 3 consisted of T7 to T10. RESULTS: Of the 528 vertebrae measured, 0% of the first group vertebrae, 10.8% of the second group vertebrae, and 69.3% of the third group vertebrae followed the rule of threes. In total, 26.7% of vertebrae followed the rule of threes, whereas 62.3% of vertebrae followed Geelhoed's rule. Additional relationships worth noting include the distance between the transverse process and the adjacent caudal transverse process on the same side is approximately 25.4 mm (1 inch), and the distance between the transverse processes of the same vertebra is approximately 50.8 mm (2 inches) for male T3-T10 vertebrae and female T1-T12 vertebrae. CONCLUSION: According to our findings, the rule of threes is not as accurate anatomically as Geelhoed's rule in locating the transverse processes of the thoracic spine. This study suggests osteopathic medical schools should teach Geelhoed's rule rather than the rule of threes.

Using anatomical landmark to avoid phrenic nerve injury during balloon-based procedures in atrial fibrillation patients.

PURPOSE: Atrial fibrillation (AF) is an arrhythmia which affects as many as 2.7 million Americans. AF should be treated, because it can lead to a four-to-fivefold increased risk of experiencing a stroke. The American College of Cardiology/American Heart Association guidelines for the treatment of drug refractory and symptomatic paroxysmal AF denote catheter ablation as the standard of care. The newest ablation treatment, cryoballoon, uses a cold balloon tip. The biggest risk factor associated with the cryoballoon ablation is phrenic nerve injury (PNI). The purpose of this study is to measure relevant distances from specific landmarks to the right phrenic nerve (RPN) to create a safe zone for physicians. METHODS: Using 30 cadaveric specimens, we measured laterally from the right superior pulmonary vein orifice (RSPV) to the RPN at the level of the sixth thoracic vertebra and laterally from the lateral border of the sixth thoracic vertebral body (T6) to the RPN. The depth and width of the left atrium (LA) were also measured to establish a cross-sectional area of the LA. The cross-sectional area of the LA was then correlated with the averaged measurements to see if the area of the LA could be a predictor of the location of the RPN. RESULTS: The average distance from the RPN-RSPV was 9.6 mm (range 4.3-18.8 mm). The average RPN-T6 distance was 30.6 mm (range 13.7-49.9 mm). There was a non-significant trend that suggests as the size of the LA increases, the measured distances also increased. CONCLUSION: Using the lateral border of the sixth thoracic vertebra as a landmark, which can be viewed under fluoroscopy during the procedure, physicians can triangulate the distance to the RSPV and determine the approximate position of the RPN. Furthermore, physicians can perform a preoperative echocardiogram to determine the size of the LA to assist in determining the position of the RPN with the hopes of avoiding injury to the RPN.

Anatomic description of the middle meatus and classification of the hiatus semilunaris into five types based upon morphological characteristics.

Anatomical variation of the lateral nasal wall, including the pathway from the frontal, ethmoidal, and maxillary sinuses may affect the communication between the paranasal sinuses and the nasal cavity. The middle meatus and hiatus semilunaris are areas where variations can occur which predispose patients to recurring sinusitis. Endoscopy allows for visualization of the entire nasal cavity, for both diagnostic and therapeutic uses. The purpose of this study was to provide an accurate characterization of the middle meatus and hiatus semilunaris for the purposes of endoscopic procedures. Ninety seven cadaveric lateral nasal walls were observed. The middle meatus was measured at three distinct points. Cranial length was also recorded. A 3D digitizer was used to record spatial relationships for the openings of the paranasal sinuses and the morphology of the hiatus semilunaris. The average widths for the middle meatus were 1.69-mm anteriorly, 2.83 mm at the transition angle, and 4.74-mm posteriorly. The posterior width was significantly larger than either of the two other measurements. The length of the hiatus semilunaris was found to be shorter on both left-sides and in females. The hiatus semilunaris was categorized into five types according to the varying morphologies. Given that the middle meatus was significantly wider posteriorly, our findings support the recommendation that entering the middle meatus posteriorly may allow an endoscopic surgeon easier access to the structures of the lateral nasal wall. Knowing the discrepancy of hiatus semilunaris lengths between right and left sides and males versus females may guide advancement of endoscopic instruments into the nasal cavity. Describing the five distinct types of the hiatus semilunaris allows the distinction of normal variation in this anatomic space versus pathologic condition.

Smaller insertion area and inefficient mechanics of the gluteus medius in females.

PURPOSE: Tears of the gluteus medius are most prevalent in middle-aged females. Recently, focus has been placed on diagnosis and treatment of tears, but an explanation for the increased prevalence still eludes researchers. We compared the area of insertion of the gluteus medius on the femur as well as three separate moment arm measures between males and females to determine if a smaller insertion area and/or decreased hip efficiency existed in females. METHODS: The gluteus medius was dissected on 37 embalmed cadaveric hips (23 M, 14 F; mean age 66.4 years) to expose its insertion on the femur, which was then outlined. Three-dimensional scans were taken of each insertion, and area measurements calculated. Reference points were placed on analogous structures within each hip, and moment arms were calculated using the x, y, z coordinates of these points. The gluteus medius insertion and three moment arm lengths were compared between the genders. RESULTS: Gluteus medius insertion area was found to be smaller in females (M 602.35 ± 116.01 mm, F 534.96 ± 98.60 mm, p = 0.034). The gluteal moment arms were also shorter in females (GMA1, M 69.87 ± 7.03 mm, F 63.22 ± 4.64 mm, p = 0.001) (GMA2, M 83.18 ± 6.69 mm, F 75.06 ± 6.23 mm, p = 0.000) with pelvic moment arms being comparable between the genders. Stature and age were not found to influence these outcomes. CONCLUSIONS: Our results suggest that in an equally massive male and female, the female will place greater mechanical demands on the gluteus medius, due to decreased efficiency as well as a relatively smaller insertion area.

Descriptive anatomy of the interscalene triangle and the costoclavicular space and their relationship to thoracic outlet syndrome: a study of 60 cadavers.

OBJECTIVE: Thoracic outlet syndrome classically results from constrictions in 1 or more of 3 specific anatomical locations: the interscalene triangle, costoclavicular space, and coracopectoral tunnel. Magnetic resonance and computed tomographic imaging studies suggest that, of the 3 potential locations for constriction, the costoclavicular space is the most susceptible to compression. This study of human cadavers aims to expand on the descriptive anatomy of the interscalene triangle and associated costoclavicular space. METHODS: The interscalene angle, interscalene triangle base, and costoclavicular space were measured on 120 sides of embalmed human cadavers. Linear distances and angles were measured using a caliper and protractor, respectively. The data were analyzed by calculating the mean, range, and standard deviation. RESULTS: The range for the interscalene base was 0 to 21.0 mm with a mean of 10.7 mm. For the interscalene angle, the range was 4° to 22° with a mean of 11.3°. Measurements for the costoclavicular space ranged from 6 to 30.9 mm with a mean of 13.5 mm. CONCLUSIONS: No significant differences were observed between left and right interscalene triangles or costoclavicular spaces; furthermore, there were no differences between the sexes concerning these 2 locations.

A possible relationship between reliability of thoracic outlet syndrome diagnostic testing and the position of the axillary artery.

PURPOSE: Publications describe variable spatial relationships between the axillary artery and brachial plexus whereby the axillary artery may be compressed by the median nerve roots when the upper extremity is hyper-abducted. The purpose of this study is to quantify the frequency of variant positioning of the axillary artery with respect to the brachial plexus, describe and quantify the lengths of the median nerve roots, and evaluate intra-arterial pressure in axillary arteries of normal and variant cadavers when the upper extremity is hyper-abducted. METHODS: Three-hundred and thirty-eight cadaveric axillae were dissected to evaluate the spatial relationship between axillary artery and the median nerve roots. Three-hundred and twelve cadaveric axillae were dissected to evaluate the lengths of the median nerve roots. Twelve cadavers were selected for evaluation of the intra-arterial pressure during a hyper-abduction procedure. RESULTS: The axillary artery was positioned anterior to the median nerve roots in 6.8% of axillae and positioned posterior to the median nerve roots in 93.2% of axillae. An experimental cohort, possessing a classic relationship between axillary artery and median nerve roots and a proximal union of the median nerve roots, showed an increase in intra-arterial pressure during hyper-abduction test. All other experimental cohorts exhibited no change in intra-arterial pressure. CONCLUSIONS: These findings suggest that the median nerve roots are capable of compressing the axillary artery when the upper extremity is hyper-abducted, the axillary artery is positioned posterior to the median nerve roots, and the patient possesses a more proximal convergence of the median nerve roots.

Functional anatomy of human scalene musculature: rotation of the cervical spine.

OBJECTIVES: Actions of the scalene muscles include flexion and lateral flexion of the cervical spine and elevation of the first and second ribs. The cervical rotational qualities of the scalene muscles remain unclear. Textbooks and recent studies report contradictory findings with respect to the cervical rotational properties of the scalene muscles. The present study was designed to take a mechanical approach to determining whether the scalene muscles produce rotation of the cervical spine. METHODS: The scalene muscles were isolated, removed, and replaced by a durable suture material. The suture material was attached at the origin and then passed through a hole on the corresponding rib near the central point of the insertion. The suture material was pulled down through the corresponding costal insertion hole to simulate contraction of each muscle. RESULTS: The simulated anterior, middle, and posterior scalene muscles, working independently and jointly, produced ipsilateral rotation of the cervical spine. The upper cervical spine rotated in the ipsilateral direction in response to the simulated muscle contraction. Findings were similar for the lower cervical spine with the exception of 2 specimens, which rotated contralaterally in response to the simulation. CONCLUSION: Experimental models of the scalene muscles are capable of producing ipsilateral rotation of the cervical spine. The findings of this study support the accepted main actions of the scalene muscles. The clinical applications for understanding the cervical rotational properties of the scalene muscles include the diagnosis, management, and treatment of cervical pain conditions as well as thoracic outlet syndrome.

Branching patterns of the lateral thoracic, subscapular, and posterior circumflex humeral arteries and their relationship to the posterior cord of the brachial plexus.

Anatomical variations in the branching pattern of the axillary artery are common and typically include the lateral thoracic, subscapular, and the posterior circumflex humeral (PCHA) arteries. Previous investigations of single specimen dissections demonstrate numerous variations to axillary artery branching, but the frequency of these occurrences is unclear. This study quantifies the frequency of variant branching of the lateral thoracic, subscapular, and posterior circumflex humeral arteries, how it they relate to the posterior cord of the brachial plexus. Axillae of 83 cadavers were dissected to allow examination of the axillary artery and its branches. Data were collected observing the branching pattern of the lateral thoracic, subscapular, and posterior circumflex humeral arteries, as well as those branches spatial relationship to the two terminal branches of the posterior cord of the brachial plexus. Some of the more common variations included the thoracodorsal artery arising from the lateral thoracic artery (LTA) (7.2%) and the subscapular artery (SSA) arising from the LTA (5.4%). The SSA also produced the LTA (4.2%) and the PCHA (12%). The PCHA also originated from the deep brachial artery (8.4%) and traversed the triangular interval to supply the deltoid muscle. These findings are relevant to both the anatomical and clinical fields as provide evidence as to the frequency of variant axillary artery branching and the potential for neurovascular elements to exist in a location other than their classical anatomical description.

GABA(B) receptor gene expression is not altered in cocaine-sensitized rats.

Recent behavioral and neurobiological data indicate that GABA(B) receptor transmission is involved in cocaine-induced hyperactivity and reinforcement. GABA(B) receptor gene expression in cocaine-sensitized rats was examined in this study. Rats were injected with cocaine (15 mg/kg, daily, i.p.) or saline for 5 consecutive days, and challenged with the same dose of cocaine after a 1-, or 20-day hiatus. The locomotor activities of rats were recorded after challenge, and the rats were killed 24 hr later. GABA(B)R1a, 1b, and GABA(B)R2 mRNA in discrete brain regions was detected by RPA and In Situ Hybridization; GABA(B)R1a protein was measured by Western blotting. Rats pretreated with cocaine developed a hyperactivity to the cocaine challenge after a 1-day or 20-day hiatus, but GABA(B)R subunit mRNA and GABA(B)R1a protein densities in the targeted regions showed no significant difference compared to those in control rats. These data indicate that GABA(B) receptor gene expression is not necessarily relevant to the behavioral sensitization of cocaine.