The myodural bridge (MDB) is a dense connective tissue structure that connects the subocciptal musculature to the spinal dura mater. The purpose of this study was to clarify morphological evolution characteristics and compositional changes in the fibrous structures of MDB during its growth and development in the atlanto-occipital interspace. For this, histological sections from Sprague-Dawley (SD) rats (age, E17 to adulthood) were stained with Masson's Trichrome and Picrosirius Red. The results demonstrated that at age E18, the posterior arch of the atlas was completely closed and MDB fibers had already begun to form. In rat embryos (E18-E21), only few fibers and muscles were present in the suboccipital region, and these were lightly stained. In postnatal rats, an obvious increase in the amount of fibers and muscle tissues was noted. At age P1, MDB fibers originated from the rectus capitis posterior minor muscle and merged into the atlanto-occipital membrane, which was closely attached to the spinal dura mater. As rats matured, MDB fibers gradually became denser and more organized. This study also showed that in postnatal rats, MDB was mainly composed of type I collagen fibers. By observing the development of MDB in SD rats, the function of MDB can be further understood. This study provides a morphological basis for future functional studies involving the MDB.
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.
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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