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Head and Neck
Published in Rui Diogo, Drew M. Noden, Christopher M. Smith, Julia Molnar, Julia C. Boughner, Claudia Barrocas, Joana Bruno, Understanding Human Anatomy and Pathology, 2018
Rui Diogo, Drew M. Noden, Christopher M. Smith, Julia Molnar, Julia C. Boughner, Claudia Barrocas, Joana Bruno
The tarsal glands are embedded in the posterior surface of each tarsal plate, the fibrous “skeleton” of the upper eyelid. The orbital septum is a sheet of connective tissue separating the superficial facial fascia and the contents of the orbit. The tarsal glands drain by orifices lying posteriorly to the eyelashes and secrete an oily substance onto the margin of the eyelids that prevents the overflow of tears (lacrimal fluid). The lacrimal gland lies in the lacrimal fossa of the frontal bone. The lacrimal sac lies posterior to the medial palpebral ligament, which is attached to the anterior lacrimal crest that forms the anterior border of the lacrimal groove (Plate 3.32). The lacrimal sac receives lacrimal fluid from the medial angle of the eye through the lacrimal canaliculi. When lacrimal fluid accumulates in excess and cannot be removed from the medial corner of the eye via the lacrimal canaliculi, it overflows the eyelids (visible crying or shedding of tears). Tears also drain into the nasal cavity via the lacrimal sac, resulting in a runny nose.
Special Senses
Published in Pritam S. Sahota, James A. Popp, Jerry F. Hardisty, Chirukandath Gopinath, Page R. Bouchard, Toxicologic Pathology, 2018
Kenneth A. Schafer, Oliver C. Turner, Richard A. Altschuler
The lacrimal fluid is drained via puncta in the medial eyelid margins into canaliculi, which open into the lacrimal sac and eventually into the nasolacrimal duct. Treatment-related alterations of the nasolacrimal duct include epithelial hyperplasia, inflammation, or blockage after the placement of stents (Breider et al. 1996; Greenman et al. 1995; Wilhelm et al. 2006).
The Bladder (BL)
Published in Narda G. Robinson, Interactive Medical Acupuncture Anatomy, 2016
Orbicularis oculi muscle, palpebral and lacrimal parts: The orbicularis oculi acts as a sphincter muscle for the eyelids. The palpebral portion shuts the lids, as when one blinks. The lacrimal portion resides deep to the palpebral part, promoting lacrimal fluid flow by compressing the lids onto the globe, and dilating the lacrimal sac by tugging on the lacrimal fascia. The neuroanatomic proximity of the orbicularis oculi and orbicularis oris motoneuronal pool in the brainstem subnuclei may explain why eyelids close during deglutition. That is, the motoneurons connect at the deglutitional center in the brainstem, such as in the nucleus tractus solitarius after intraoral trigeminal afferents activate swallowing centers and, simultaneously, efferent fibers to the orbicularis oculi muscle.4
Fabrication of nanostructured lipid carriers ocugel for enhancing Loratadine used in treatment of COVID-19 related symptoms: statistical optimization, in-vitro, ex-vivo, and in-vivo studies evaluation
Published in Drug Delivery, 2022
Rehab Abdelmonem, Inas Essam Ibrahim Al-Samadi, Rasha M. El Nashar, Bhaskara R. Jasti, Mohamed A. El-Nabarawi
Nanostructured lipid carriers (NLCs) are considered the modified generation of solid lipid nanoparticles, incorporating both liquid and solid lipid as an oil matrix (Hosny et al., 2022). NLCs are better than other conventional nanocarriers in improving the solubility, drug loading of lipophilic drugs, and trans-corneal penetrability, which provides a property of controlled and prolonged release of drug (Mishra et al., 2016). It is fabricated with biodegradable lipids and offers greater solubility and bioavailability (Gilani et al., 2021b). Most topical treatments available on the market are aqueous emulsions or solutions of the drug, however, such topical treatments have some drawbacks, as the rapid mixing of eye drops with the lacrimal fluid reducing drug’s half-life on the ocular surface (estimated to be ∼4 min) before being removed from the eye through nasolacrimal drainage and the conjunctival vasculature. As such, there is significant interest in identifying methods to improve the residence time of the drug on the ocular surface and thus increase its bioavailability (Dave et al., 2021). Mucoadhesive ocugel drug delivery systems obtained their mucoadhesive properties from HPMC K100 polymer which has a relatively high viscosity, thus, extending retention time in the cornea and conjunctival sac, and sustaining drug release despite some physiological responses for example, the nasolacrimal draining reflex and ocular blinking (Mamatha et al., 2022).
Should We Reconsider the Classification of Patients with Dry Eye Disease?
Published in Ocular Immunology and Inflammation, 2021
Maurizio Rolando, Manfred Zierhut, Stefano Barabino
We now know that dry eye disease is a progressive disease that affects the entire ocular surface unit.5 Both reduced aqueous tear flow caused by impaired lacrimal fluid delivery and increased tear film evaporation caused by an environmental stressor or Meibomian gland dysfunction contribute to hyperosmolarity and nerve terminal overstimulation, triggering a cascade of events involving other parts of the ocular surface unit.5–7 Progressive dry eye disease affects multiple components of the ocular surface unit including epithelial cells, goblet cells, the lid margin, tear film, and the spreading and composition of lipids. Eventually, early dry eye disease becomes an irreversible chronic inflammatory condition exacerbated by reduced aqueous tear flow, increased tear film evaporation, and repeated nerve stimulation.8 If the disease remains untreated, these processes result in a self-perpetuating vicious circle of inflammation leading to treatment-refractory disease and permanent damage to the ocular surface.9,10
Towards Lacrimal Gland Regeneration: Current Concepts and Experimental Approaches
Published in Current Eye Research, 2020
Jana Dietrich, Stefan Schrader
The lacrimal gland is a mainly serous, tubule-acinar gland. Histologically, it is composed of acinar cells, which are arranged in individual functional units (the acini) and surrounded by ductal and myoepithelial cells (Figure 1). The acinar cells are responsible for the production and secretion of the primary lacrimal fluid2, which is then conducted onto the ocular surface. On the ocular surface, the tear film is formed and improves the optical properties of the ocular surface by generating a smooth surface on the corneal epithelium, moistening and nourishing the epithelial cells of the conjunctiva and cornea, removing dust and debris and protecting against pathogens.3 The lacrimal fluid with its complex composition of inorganic salts, immunoglobulin A and various proteins is important for this purpose.4 Consequently, an interruption of lacrimal gland homeostasis resulting in a disturbance of the physiological composition and/or quantity of lacrimal fluid, may lead to the development of ADDE.