Surgical and Radiologic Anatomy最新文献

Introduction: This study aims to investigate the anatomical variations in the median nerve and its branches, specifically focusing on their distribution to the muscles and the points at which they enter the muscles. In addition, the branching level of the ramus muscularis of the median nerve supplying the thenar muscles was examined to explore potential correlations with carpal tunnel syndrome. Understanding these variations is crucial for minimizing iatrogenic nerve damage during surgical procedures in the carpal tunnel region.

Methods: Dissections were conducted on 15 forearm and wrist specimens, including 8 right-sided cadavers and 7 left-sided cadavers. The muscle branch entry levels into the thenar region were measured, and the nerve was classified according to Lanz's classification system during the opening of the flexor retinaculum. Parameters such as the height of the first branch of the median nerve relative to the z-line (interstyloid line), the relationship of the nerve's muscular branch to the flexor retinaculum, the level of entry of the muscle branch into the muscle (relative to the z-line), muscle length, and the ratio of the entry level of the first branch to muscle length were examined.

Results: Four types of median nerve branching were observed according to Lanz's classification. The extraligamentous type was the most common, found in 53% of the specimens. In preligamentous types, the branches emerged on average 13.37 ± 5.69 mm inferiorly, except for those relative to the z-line. The entry level of the muscle branch into the muscle was most frequently located in the upper third of the thenar region. The average length of the thenar region was measured to be 11.40 ± 1.02 mm. The high frequency (53%) of the extraligamentous type in our study aligns with the findings in the general literature. However, the discovery of an additional preligamentous accessory motor branch in 46% of cases is a noteworthy observation, highlighting a higher rate than previously documented.

Conclusion: These branching patterns suggest the need for careful consideration of accessory branches during surgical procedures in the carpal tunnel region. In particular, during carpal tunnel surgeries, it is recommended to assess the relationship between the motor branch of the median nerve and the flexor retinaculum before releasing it, as variations in branching could have implications for surgical outcomes.

Though small, the ascending pharyngeal artery (APA) is surgically significant due to its proximity to the internal carotid artery (ICA) and supply to critical neurovascular structures. We present a unique arterial variant identified by computed tomography angiography (CTA) in a 52-year-old male. On the left side, the APA originated in common with a short linguofacial trunk (LFT) that further gave rise to the lingual and facial arteries (LA and FA), forming a trifurcated LA-FA-APA trunk. On the right side, an independent LFT was present, with the APA originating separately from the external carotid artery (ECA). CTA with three-dimensional reconstruction is essential for detecting rare vascular configurations and should be part of the preoperative evaluation for head and neck surgeries and endovascular procedures.

Purpose: Distal biceps tendon repair is a common procedure with a risk of iatrogenic nerve injury, including the posterior interosseous nerve (PIN). This study aimed to define the anatomical relationship of the PIN to key elbow landmarks, particularly the radial tuberosity, and to identify safe zones for retractor placement during surgery.

Methods: Twenty-nine fresh cadaveric upper extremities were dissected by a fellowship-trained shoulder and elbow surgeon. Measurements included the bifurcation point of the radial nerve into the PIN and superficial radial nerve. We measured the PIN's distance from the radiocapitellar joint (RCJ) and its relation to the radial tuberosity in both pronation and supination. The safe positioning of retractors relative to the radial tuberosity was also evaluated.

Results: The radial nerve bifurcated approximately 5 ± 3 mm proximal to the RCJ. The PIN entered the supinator (Arcade of Frohse) at 22 ± 1 mm distal to the RCJ. It was located a mean of 13 ± 2 mm from the radial border of the radial tuberosity in pronation and 19 ± 2 mm in supination. In all specimens, the PIN distal to the arcade was surrounded by muscle, with no direct contact with bone. Safe retractor placement was ulnar to the tuberosity proximally and radial distally in supination.

Conclusion: Supination increases the separation between the PIN and the tuberosity by ~ 5 mm, supporting ulnar proximal and radial distal retractor placement (narrow right-angled/Langenbeck) to reduce iatrogenic injury.

Level of evidence: IV (Anatomical cadaveric study).

Objective: The posterior canaliculus (PC) is a critical landmark in otologic surgery, but a quantitative in vivo characterization of its postnatal development is lacking. This study aimed to utilize the ultra-high spatial resolution of photon-counting detector computed tomography (PCD-CT) to conduct a definitive in vivo morphometric analysis of the PC's length and its spatial relationship to the mastoid segment of the facial nerve (FN) across a wide age range in a Japanese population, characterizing its developmental trajectory and variability.

Methods: This retrospective, cross-sectional study analyzed temporal bone PCD-CT scans from 128 consecutive Japanese patients (265 sides), aged 0 to 59 years. Using multiplanar reconstructions, the length of the PC (PC length) and the distance between the PC and the mastoid segment of the FN (PC-FN distance) at the level of the tympanic entry were measured. The relationships between these parameters and age were analyzed using locally estimated scatterplot smoothing (LOESS).

Results: The mean PC length was 8.31 ± 2.50 mm (range: 2.59-14.58 mm), and the mean PC-FN distance was 2.80 ± 0.74 mm (range: 1.01-6.18 mm). LOESS analysis revealed a distinct developmental trajectory: PC length increased progressively from birth, plateauing around age 20, with the most rapid growth occurring in the first year of life. Conversely, PC-FN distance decreased from birth, stabilizing around age 9. Both parameters exhibited significant inter-individual variability, particularly in the pediatric cohort. Notably, the PC was unidentifiable in 14 temporal bones, all from patients under 10 years old (mean age: 2.3 years).

Conclusion: This study provides the first in vivo quantitative evidence of the PC's postnatal morphogenesis, demonstrating significant elongation and a concurrent narrowing of PC-FN distance during childhood. This dynamic anatomical development, coupled with high individual variability, defines a "high-risk window" in pediatric otologic surgery. The findings underscore the necessity of preoperative high-resolution imaging for patient-specific surgical planning and highlight the transformative capability of PCD-CT in micro-anatomical research.

Purpose: Morphometric data quality depends on validity-how well a tool measures its intended variable-and reliability-the consistency of repeated measurements. This study investigates how the reliability of digital morphometric measurements correlates with the measurer's level of professional experience and their patterns of technology usage.

Methods: A total of 21 medical students (inexperienced group) and 18 anatomists (experienced group) participated in the study. Participants first filled out a questionnaire addressing demographic information, experience levels, and technology usage behaviors. Following this, they underwent a 2-hour training session on ImageJ, a software utilized for digital morphometric analysis. Participants were then instructed to measure seven parameters (five linear, two angular) on images of 10 individuals, performing the measurements at multiple time points. Reliability was evaluated using the technical error of measurement (TEM), relative technical error of measurement (rTEM), and coefficient of reliability (R). Statistical analysis included Chi-square tests for categorical data and Mann-Whitney U tests for continuous variables, using SPSS 22.

Results: There were no statistically significant differences between groups regarding gender distribution and hand dominance (p > 0.05), although notable differences in age and technology usage patterns were observed (p <  0.05). The experienced participants showed more frequent use of ImageJ (p <  0.05). Following the training, both groups showed comparable measurement times and reliability outcomes (p > 0.05).

Conclusion: The findings suggest that, with sufficient instruction, digital morphometric assessments using ImageJ can yield reliable results regardless of the user's level of professional experience, underscoring the critical role of training in digital measurement proficiency.