Recent studies have identified that the myodural bridge (MDB) is located between the suboccipital muscles and cervical dura mater in the posterior atlanto-occipital interspace within humans. The myodural bridge has been considered to have a significant role in physiological functions. However, there is little information about the myodural bridge in marine mammals; we conducted this study to investigate and examine the morphology of the myodural bridge in a sperm whale. We also aim to discuss the physiological functions of the myodural bridge. In this study, a 15.1-meter long sperm whale carcass was examined. Multiple methods were conducted to examine the bridges of the sperm whale which included dissection, P45 plastination and histological analysis. This study confirmed the existence of the myodural bridge in the sperm whale and shows there are two types of the bridge in the sperm whale: one type was the occipital-dural bridge (ODB), the other type was the MDB. A large venous plexus was found within the epidural space and this venous plexus is thought to contain a great amount of blood when in deep water and thus the movements of suboccipital muscles could be a unique power source that drives cerebrospinal fluid circulation.
This study evaluated the anatomical features of preseptal and preaponeurotic fat tissues in the upper eyelids of individuals of Asian heritage. Specifically, we attempted to elucidate the role of these tissues in the formation of sunken upper eyelids and devise an easy and feasible approach to rectify this. Sixteen heads (32 facial halves) from fresh adult cadavers were processed using the P45 plastination techniques. The polymer resulted in transparent plastination, and the sagittal median section of the eyeballs was dissected. Gross anatomy results of 12 adult cadaveric heads (24 facial halves) were included as supplementary data. The orbital septum was observed on sagittal section slides prepared with P45 sheet plastination. Based on the amount of fat distribution, the upper eyelid was classified into three groups: preseptal fat predominant type, preaponeurotic fat predominant type, and orbital septum equilibrium type (relative distribution of 31.3, 12.5, and 56.3 % in plastinated slices, and 29.2, 16.7, and 54.2 % in gross anatomical studies). Major tissues on P45 sheet plastination slices in the supraorbital region were preseptal fat, preaponeurotic fat, frontalis muscle and frontalis muscle aponeurosis, and partial orbicularis oculi muscle. The muscle fibers of the frontalis muscle and orbicularis oculi were interconnected and extended backward to connect with the orbital septum through preseptal fat. In conclusion, the morphology and external appearance of the upper eyelids depend on the relative relationship between preseptal and preaponeurotic fat tissues. Mildly or moderately sunken upper eyelids can be corrected by modifying the soft tissue in the supraorbital margin.
Purpose: Ocular suspensory ligament is an important part of the lower eyelid retractors. However, there is a scarcity of studies examining detailed en-block histologies of ocular suspensory ligaments. Methods: In this study, we included the cadavers of Chinese adults as subjects. These cadavers of Chinese adults were processed using P45 plastination techniques. The polymer resulted in transparent plastination, and the P45 sheet-plastinated sections of the lower eyelid were observed. The gross anatomy results of three Chinese adult heads (six hemifaces) were included as gross dissection data. All photographic documentation was performed via a Canon EOS 7D Mark camera. Results: The results showed that the inferior rectus muscle, inferior oblique muscle, ocular suspensory ligament, and its arcuate expansion are under the eyeball. The medial and lateral parts of the ocular suspensory ligament end at the medial and lateral canthal ligament. The middle part, a hammock-like shape, is slightly lower. The ocular suspensory ligament holds up the inferior oblique muscle, inferior rectus muscle, and the eyeball. As the inferior oblique muscle passes through the sheath of the inferior rectus, the fascia is thickened, forming the ocular suspensory ligament. The ocular suspensory ligament connects to the intermuscular septum, the inferior tarsal muscle, and the medial and lateral check ligaments. Conclusion: This study observed the ocular suspensory ligament and arcuate expansion through P45 sheet plastination for the first time and identified the distribution of the lower eyelid ligaments, thus laying the foundation for further research.
Type 2 diabetes mellitus (T2DM) is becoming a significant health issue worldwide. Many studies support the hypothesis that patients with T2DM have a higher-than-expected incidence of mild cognitive impairment (MCI) than individuals without diabetes. Based on the results from recent studies, MCI might be associated with the effects of T2DM on glucose metabolism and brain atrophy. As a narrative review, we will illuminate pathological and cognitive changes in patients with T2DM and comorbid MCI and protective hypoglycemic therapies. The early abnormal signs of cognition must be elucidated, and extensive investigations are needed to develop improved therapies for use in the clinic.
Background: To study the anatomical characteristics of retro-orbicularis oculi fat (ROOF) in the upper eyelid and to investigate its relevance in upper eyelid surgery.Methods: Thirty-eight Chinese hemifacial cadaver specimens were used. Several sagittal plane section planes were recorded from the medial canthus to the lateral canthus of the eyelid after P45 sheet plastination.ROOF and the associated orbital septum connective tissues in the 38 hemifaces were studied. According to the anatomic results, the lowest point of the junction of the orbital septum and the ROOF (SRJ) was raised for surgical dissection. We improved the intraoperative management of patients who underwent upper eyelid surgery in the plastic surgery department of the First Affiliated Hospital of Dalian Medical University in 2019. Patients were evaluated by observation and self-assessment.Results: ROOF is fascia adipose tissue. In the upper portion of upper eyelid, ROOF fibers were observed to be extremely dense and continuous with the fascia on the surfaces of orbicularis oculi muscle, the periosteum of the orbital margin, and the orbital septum. In the middle portion, positional relationships were identified between the lowest point of the SRJ and the lowest point of the junction of the orbital septum and the levator palpebrae superioris (SAJ). Lifting the SRJ significantly increased the upper eyelid reflex distance in all 57 patients. Conclusions: ROOF is an important factor in upper eyelid surgery. Lifting the SRJ effectively improves the retraction force of the levator palpebrae superioris muscle (LPS)
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