The masseteric nerve for facial reanimation: Macroscopic and histomorphometric characteristics in 106 human cadavers and comparison of axonal ratio with recipient nerves.

Peripheral facial palsy causes severe impairments. Sufficient axonal load is critical for adequate functional outcomes in reanimation procedures. The aim of our study was to attain a better understanding of the anatomy of the masseteric nerve as a donor, in order to optimize neurotization procedures. Biopsies were obtained from 106 hemifaces of fresh frozen human cadavers. Histological cross-sections were fixed, stained with PPD, and digitized. Histomorphometry and a validated software-based axon quantification were conducted. Of the 154 evaluated branches, 74 specimens were of the main trunk (MT), 40 of the anterior branch (AB), and 38 of the descending branch (DB), while two halves of one cadaver featured an additional branch. The MT showed a diameter of 1.4 ± 0.41 mm (n = 74) with 2213 ± 957 axons (n = 55). The AB diameter was 0.9 ± 0.33 mm (n = 40) with 725 ± 714 axons (n = 30). The DB diameter was 1.15 ± 0.34 mm (n = 380) with 1562 ± 926 axons (n = 30). The DB demonstrated a high axonal capacity - valuable for nerve transfers or muscle transplants. Our findings should facilitate a balanced selection of axonal load, and are potentially helpful in achieving more predictable results while preserving masseter muscle function.

Visualization of the carotid body in situ in fixed human carotid bifurcations using a xylene-based tissue clearing method.

The anatomy of the carotid body (CB) and its nerve supply are important, because it is a potential therapeutic target for treatment of various clinical conditions. Visualization of the CB in situ in fixed human anatomical specimens is hampered by obscuring adipose and connective tissues. We developed a tissue clearing method to optimize identification of the CB. We used single sided carotid bifurcations of six human cadavers fixed long term. Visualization of the CB was accomplished by clearing tissue with xylene. Under incident light, carotid bifurcations exhibited a less transparent, darker colored CB; hematoxylin and eosin stained paraffin sections confirmed its identity. Our visualization of the CB in situ in human carotid bifurcations fixed long term enabled targeted resection and subsequent topographic and morphometric measurements of the CB. Our procedure does not interfere with immunohistochemical staining of sections prepared from such specimens.

The nerve supply to the pectoralis major: An anatomical study and clinical application of the denervation in subpectoral breast implant surgery.

BACKGROUND: Using the subpectoral approach, animation deformity or breast distortion due to pectoralis muscle contraction is common. Although the anatomy of the pectoral nerves has been extensively studied, only few studies have related the location of these nerves to bony landmarks. OBJECTIVE: Our aim is to clarify the anatomy and possible variations of the innervation of the pectoralis major in relation to bony landmarks useful for surgery and to identify the preferred level for (selective) denervation by 1) transecting the nerves and 2) splitting the muscle in subpectoral breast implant surgery in cadavers. METHODS: Fourteen pectoral regions (both left and right side) were dissected on 7 formaldehyde-fixed cadavers. The origin, locations, and course were mapped and (distances to) landmarks were reported. RESULTS: The lateral pectoral nerve, medial pectoral nerve, and ansa pectoralis were identified in all cadavers. Nerve branches pierce the pectoralis minor or run along its upper or lower border. The piercing nerves vary from one to three branches and were consistently located lateral to the midclavicular line. The horizontal and vertical distances to bony landmarks varied greatly and depended on the size and location of the pectoralis minor, except for the nerve running along the upper border of the PMin, which was located consistently around 30% of the clavicular line from the acromioclavicular joint to the sternoclavicular joint. CONCLUSION: We were unable to define a fixed landmark to mark pre- or peroperatively. However, we could define guidelines that help to identify and excise or preserve nerves of interest.

Histologic Comparison of the Dura Mater among Species.

The biocompatibility, biodegradation, feasibility, and efficacy of medical devices like dural sealants and substitutes are often evaluated in various animal models. However, none of these studies explain the rationale for choosing a particular species, and a systematic interspecies comparison of the dura is not available. We hypothesized that histologic characteristics of the dura would differ among species. We systematically investigated basic characteristics of the dura, including thickness, composition, and fibroblast orientation of the dura mater, in 34 samples representing 10 animal species and compared these features with human dura by using hematoxylin and eosin staining and light microscopy. Dura showed many similarities between species in terms of composition. In all species, dura consisted of at least one fibrovascular layer, which contained collagen, fibroblasts, and blood vessels, and a dural border cell layer beneath the fibrovascular layer. Differences between species included the number of fibrovascular layers, fibroblast orientation, and dural thickness. Human dura was the thickest (564 µm) followed by equine (313 µm), bovine (311 µm), and porcine (304 µm) dura. Given the results of this study and factors such as gross anatomy, feasibility, housing, and ethical considerations, we recommend the use of a porcine model for dural research, especially for in vivo studies.

The pecs anesthetic blockade: A correlation between magnetic resonance imaging, ultrasound imaging, reconstructed cross-sectional anatomy and cross-sectional histology.

The interfascial thoracic wall blockades Pecs I and Pecs II are increasingly applied in breast and axillary surgery. Despite the clear anatomical demarcations depicted at their introduction, the clinical outcome is more variable than would be expected based upon the described anatomy. In order to elucidate factors that explain this variability, we evaluated the spread of each injection-medial Pecs I, lateral Pecs I, the deep injection of the Pecs II-separately. A correlation of in vivo landmarks and ultrasound images with ex vivo ultrasound, reconstructed anatomical planes, histology and magnetic resonance imaging. The medial Pecs I, similar to the sagittal infraclavicular block positioning with needle position medial to the pectoral branch of the thoracoacromial artery, reaches the medial and lateral pectoral nerves. The lateral Pecs I, below the lateral third of the clavicle at the level of the third rib with needle position lateral to the pectoral branch of the thoracoacromial artery, additionally spreads to the axilla and reaches the intercostobrachial nerve. The deep Pecs II injection spreads to the lateral cutaneous part of the III-VI intercostal nerves and reaches the long thoracic nerve. The variability of the Pecs anesthetic blockades is driven by the selected Pecs I approach as only the lateral approach stains the intercostobrachial nerve. The pectoral branch of the thoracoacromial artery can serve as the landmark to differentiate the needle position of the medial and lateral Pecs I block. Clin. Anat. 32:421-429, 2019. © 2019 Wiley Periodicals, Inc.

Solute transport at the interface of cartilage and subchondral bone plate: Effect of micro-architecture.

Cross-talk of subchondral bone and articular cartilage could be an important aspect in the etiology of osteoarthritis. Previous research has provided some evidence of transport of small molecules (~370Da) through the calcified cartilage and subchondral bone plate in murine osteoarthritis models. The current study, for the first time, uses a neutral diffusing computed tomography (CT) contrast agent (iodixanol, ~1550Da) to study the permeability of the osteochondral interface in equine and human samples. Sequential CT monitoring of diffusion after injecting a finite amount of contrast agent solution onto the cartilage surface using a micro-CT showed penetration of the contrast molecules across the cartilage-bone interface. Moreover, diffusion through the cartilage-bone interface was affected by thickness and porosity of the subchondral bone as well as the cartilage thickness in both human and equine samples. Our results revealed that porosity of the subchondral plate contributed more strongly to the diffusion across osteochondral interface compared to other morphological parameters in healthy equine samples. However, thickness of the subchondral plate contributed more strongly to the diffusion in slightly osteoarthritic human samples.

Manganese-enhanced MRI of brain plasticity in relation to functional recovery after experimental stroke.

Restoration of function after stroke may be associated with structural remodeling of neuronal connections outside the infarcted area. However, the spatiotemporal profile of poststroke alterations in neuroanatomical connectivity in relation to functional recovery is still largely unknown. We performed in vivo magnetic resonance imaging (MRI)-based neuronal tract tracing with manganese in combination with immunohistochemical detection of the neuronal tracer wheat-germ agglutinin horseradish peroxidase (WGA-HRP), to assess changes in intra- and interhemispheric sensorimotor network connections from 2 to 10 weeks after unilateral stroke in rats. In addition, functional recovery was measured by repetitive behavioral testing. Four days after tracer injection in perilesional sensorimotor cortex, manganese enhancement and WGA-HRP staining were decreased in subcortical areas of the ipsilateral sensorimotor network at 2 weeks after stroke, which was restored at later time points. At 4 to 10 weeks after stroke, we detected significantly increased manganese enhancement in the contralateral hemisphere. Behaviorally, sensorimotor functions were initially disturbed but subsequently recovered and plateaued 17 days after stroke. This study shows that manganese-enhanced MRI can provide unique in vivo information on the spatiotemporal pattern of neuroanatomical plasticity after stroke. Our data suggest that the plateau stage of functional recovery is associated with restoration of ipsilateral sensorimotor pathways and enhanced interhemispheric connectivity.