Training on skin flap elevation in hand surgery using cadavers embalmed by the saturated salt solution method: effectiveness and usefulness.

Thiel embalmed and fresh-frozen cadavers have been mainly used for hand surgery training. We held a training seminar on skin flap elevation using cadavers embalmed by the saturated salt solution method. This study aimed to evaluate the usefulness of such training and to validate the suitability of saturated salt solution-embalmed cadavers for hand surgery training. Participants were trained in elevation procedures for the oblique triangular, reverse digital artery, reverse radial forearm, and reverse dorsal metacarpal artery flaps. Forty-eight surgeons participated in three seminars (one held in 2017, 2018, and 2019 each). A self-assessment of the participants' confidence levels for their surgical skills was performed before and immediately after the seminar, and the suitability of saturated salt solution-embalmed cadavers was determined in terms of visual perception, tactility, comparison with real-world surgical settings, and usefulness. The confidence level for all skills increased immediately after the seminar. The surgeons reported that the visual perception and tactility of the saturated salt solution-embalmed cadavers were comparable to those of a living body, and the cadavers were rated higher with respect to their usefulness. Hand surgery seminars using cadavers embalmed by the saturated salt solution method are considered useful for training in skin flap techniques.

Advanced cadaver-based educational seminar for trauma surgery using saturated salt solution-embalmed cadavers.

AIM: Senior surgeons in Japan who participated in "cadaver-based educational seminar for trauma surgery (CESTS)" subsequently stated their interest in seminars for more difficult procedures. Therefore, we held a 1-day advanced-CESTS with saturated salt solution (SSS)-embalmed cadavers and assessed its effectiveness for surgical skills training (SST). METHODS: Data were collected from three seminars carried out from September 2015 to January 2018, including a 10-point self-assessment of confidence levels (SACL) questionnaire on nine advanced surgical skills, and evaluation of seminar content before, just after, and half a year after the seminar. Participants assessed the suitability of the two embalming methods (formalin solution [FAS] and SSS) for SST, just after the seminar. Statistical analysis resulted in P < 0.0167 comparing SACL results from seminar evaluations at the three time points and P < 0.05 comparing FAS to SSS. RESULTS: Forty-three participants carried out surgical procedures of the lung, liver, abdominal aorta, and pelvis and extremity. The SACL scores increased in all skills between before and just after the seminar, but were decreased by half a year after. However, SACL scores of each skill did not change significantly, except for external fixation for pelvic fracture at just after and half a year after. The SSS-embalmed cadavers were evaluated as being more suitable than FAS-embalmed cadavers for each procedure. CONCLUSIONS: Advanced-CESTS using SSS-embalmed cadavers increased the participants' self-confidence just after the seminar, which was maintained after half a year in each skill, except external fixation for pelvic fracture. Therefore, SSS-embalmed cadavers are useful for SST, particularly for surgical repairs.

Middle thymothyroid artery arising from the common carotid artery: case report of a rare variation.

A middle thymothyroid artery, arising from the anterior aspect of the right common carotid as an anomalous branch was observed in a 71-year-old Japanese male cadaver. It soon divided into a thyroidea ima artery, a branch supplying the sternoclavicular joints, and a thymic branch. In addition, twigs from these three main branches supplied the sternohyoid and sternothyroid muscles, right inferior parathyroid gland and also some deep cervical lymph nodes. Anatomical features, clinical implications and a brief account of the developmental aspects of this rare variation are included in this report.

Nerve communication between the glossopharyngeal nerve, external carotid plexus and the superficial cervical ansa: human autopsy case.

The authors encountered a very rare human autopsy case in which the supernumerary branch of the glossopharyngeal nerve and a nerve branch arising from the external carotid plexus communicated with the superficial cervical ansa. This anomaly was observed on the left side of a 71-year-old male cadaver during the gross anatomical seminar at Niigata University in 2004. The nerve fascicle and fiber analyses indicated that the supernumerary branch of the glossopharyngeal nerve separated cranial to the branches to the pharyngeal constrictor muscles, carotid sinus and stylopharyngeal muscle and sent the nerve fibers to the muscular branches to the platysma and the cutaneous branches to the cervical region. Additionally, it was shown that the branch arising from the external carotid plexus sent the nerve fibers to the cutaneous branch to the cervical region. Although the external carotid plexus is primarily postganglionic sympathetic fibers originating from the superior cervical ganglion, the vagus and glossopharyngeal nerves gave off branches connecting to the plexus, and therefore it was not possible to determine the origins of this branch of the external carotid plexus. The present nerve fascicle analysis demonstrates that the supernumerary branch of the glossopharyngeal nerve, which innervated the platysma, did not share any nerve components with the branches to the pharyngeal constrictor muscles, carotid sinus and stylopharyngeal muscle, suggesting that this supernumerary branch may be categorized into the different group from these well-known branches.

Constancy and characteristics of the anterior cutaneous branch of the first intercostal nerve: correcting the descriptions in human anatomy texts.

Human anatomy texts state that the anterior cutaneous branch of the first intercostal nerve (Rca-Th1) does not exist or that, even if it does, it is poorly developed. However, an anterior cutaneous branch in the first intercostal space (Rca-1) was observed in 74.8% of cases examined (104/139 sides) and was not poorly developed at all. Some of the observed Rca-I were even larger than the anterior cutaneous branches in the second intercostal space (Rca-ll). The segment of origin of the Rca-I was analyzed in 37 sides and 66.2% (49/74 branches) were confirmed to be from Th1. As a result, in contrast with traditional beliefs, it was shown that Rca-Th1 exists. The Rca-I was classified into two types according to the course and distribution: (i) an anterior cutaneous branch that appeared at the anterior end of the first intercostal space (ICS), ran through the pectoralis major muscle and extended in the first ICS (Rca-1); and (ii) another branch that appeared at the same place but ran downward along the anterior surface of the second costal cartilage, deep to the pectoralis major muscle, to reach the inferior edge of the second costal cartilage or the second ICS, passed through the pectoralis major muscle and extended to the second rib or the second ICS (pseudo Rca-2). It was found that 77.8% (35/45 branches) of Rca-1 and 48.3% (14/29 branches) of pseudo Rca-2 were derived from Th1. Accordingly, the author suggests that the description in human anatomy texts should be revised to read, '... the Rca-Th1 exists quite constantly and some of appear at a position resembling Rca-Th2'.

[Reexamination of the communicating branch between the sural and tibial nerves].

Reexamination of communicating branches between the sural and tibial nerves ventral to the calcanean tendon was carried out on 52 legs of 26 Japanese cadavers which were used for ordinary dissection practices at the Niigata University School of Medicine. Communicating branches were found in 7 out of 52 dissections (13.5% of cases). In three of the 7 specimens, the communicating branch, the sural nerve and the tibial nerve with the deep crural fascia were removed from the legs and demonstrated by a modified Sihler's staining technique. Three types of communicating branches, Y, U and N, were distinguished on the basis of their shapes. In type Y, a medial branch from the sural nerve and a branch from the tibial nerve joined in Y-shape and become one terminal branch. In type U, the both branches formed a loop between the sural and tibial nerves. The type N communicating branch ran obliquely and medially to reach the tibial nerve distally. Only the Y type appeared in 5 specimens. Both the Y and U type and the Y and N types occurred in one specimen each. We assume that the communicating branch of the N type contains motor fibers which are derived from the sural nerve and innervate some plantar muscles, because this type is correspond to the communication type of some animals in which motor fibers have been demonstrated. Therefore, if the sural nerve biopsy is performed to examine a pure sensory nerve, removal of the more distal part of the sural nerve than a diverging point of a communicating branch is recommended. This study also indicated that the modified Sihler's staining technique is useful to examine distributions of cadaveric peripheral nerves after medical students' dissection course.

Formation and distribution of the sural nerve based on nerve fascicle and nerve fiber analyses.

The formation and distribution of the sural nerve are presented on the basis of an investigation of 31 legs of Japanese cadavers using nerve fascicle and fiber analyses. Nerve fibers constituting the medial sural cutaneous nerve were designated as 'T', whereas those constituting the peroneal communicating branch were designated as 'F'. In 74.2% of cases (23/31), the T and F fibers joined each other in the leg, whereas in 9.7% of cases (3/31) they descended separately. In 16.1% of cases (5/31), the sural nerve was formed of only the T fibers. The sural nerve gave off lateral calcaneal branches and medial and lateral branches at the ankle. The lateral calcaneal branches always contained T fibers. The medial branches consisted of only T fibers, whereas most of the lateral branches consisted of only F fibers (71.0%; 22/31). In addition to the T and F fibers, P fibers, which derived from the superficial and deep peroneal nerves, formed the dorsal digital nerves. The P fibers were entirely supplied to the medial four and one-half toes. However, they were gradually replaced by the T and F fibers in the lateral direction. The 10th proper dorsal digital nerve consisted of T fibers only (38.7%; 12/31), of F fibers only (19.4%; 6/31) or of both T and F fibers (38.7%; 12/31). These findings suggest that the T fibers are essential nerve components for the skin and deep structures of the ankle and heel rather than the skin of the lateral side of the fifth toe. The designation of the medial sural cutaneous nerve should be avoided and only the T fibers are appropriate components for naming as the sural nerve.

[Application of the modified Sihler's stain technique to cadaveric peripheral nerves after medical students' dissection course].

The exact ramification and distribution pattern of the peripheral nerves is one of the most important information for anatomists and clinicians. However, it is very difficult to pursue perfectly all of the fine twigs of nerve branches even if we use a stereoscopic microscope. Recently, Liu et al. (Anat. Rec., 247: 137, 1997) applied a modified Sihler's stain technique to study the distribution of intramuscular nerve branches in mammalian skeletal muscles. Then, we attempted to apply this technique to plantar nerves of human foot removed from cadavers which were used for ordinary dissection practices at the School of Medicine. Intrinsic muscles of the foot with motor and sensory nerve branches were removed en bloc from bones of the foot. They were macerated and depigmented in 3% aqueous potassium hydroxide, decalcified in Sihler's solution 1. Then, after staining in Sihler's solution II, they were destained in Sihler's solution I, neutralized in 0.05% lithium carbonate, and cleared in increasing concentrations of glycerin. As a result, each nerve fascicle, which are bundles of nerve fibers invested by the perineurium, was very clearly visualized, since only nerve fibers were stained deep blue-purple, while muscles, the epineurium and the perineurium were made transparent in glycerin. We found an anastomosis between a deep branch of the lateral plantar nerve and the medial plantar nerve, composed of several nerve fascicles. Therefore, the modified Sihler's stain technique can be applied to cadaveric peripheral nerves after medical students' dissection course.