Tears are a clear liquid secreted by the lacrimal glands found in the eyes of all land mammals. Their functions include lubricating the eyes, removing irritants, and aiding the immune system. Tears also occur as a part of the body's natural pain response. Humans are not the only mammals known to produce tears as part of an emotional response, such as out of joy or grief. Elephants have been crying during mourning periods. Tears have symbolic significance among humans. Emotional secretion of tears may serve a biological function by excreting stress-inducing hormones built up through times of emotional distress. Tears are made up of water, electrolytes, proteins, lipids, and mucins that form layers on the surface of eyes. The different types of tears—basal, reflex, and emotional—vary significantly in composition.
The nasolacrimal duct carries tears from the lacrimal sac of the eye into the nasal cavity. The duct begins in the eye socket between the maxillary and lacrimal bones, from where it passes downwards and backwards. The opening of the nasolacrimal duct into the inferior nasal meatus of the nasal cavity is partially covered by a mucosal fold.
Papilla or papillae may refer to:
The lacrimal glands are paired exocrine glands, one for each eye, found in most terrestrial vertebrates and some marine mammals, that secrete the aqueous layer of the tear film. In humans, they are situated in the upper lateral region of each orbit, in the lacrimal fossa of the orbit formed by the frontal bone. Inflammation of the lacrimal glands is called dacryoadenitis. The lacrimal gland produces tears which are secreted by the lacrimal ducts, and flow over the ocular surface, and then into canals that connect to the lacrimal sac. From that sac, the tears drain through the lacrimal duct into the nose.
The orbicularis oculi is a muscle in the face that closes the eyelids. It arises from the nasal part of the frontal bone, from the frontal process of the maxilla in front of the lacrimal groove, and from the anterior surface and borders of a short fibrous band, the medial palpebral ligament.
The term Lacrimal or lachrymal, may refer to:
The lacrimal apparatus is the physiological system containing the orbital structures for tear production and drainage.
It consists of:
The lacrimal canaliculi,, are the small channels in each eyelid that drain lacrimal fluid, from the lacrimal puncta to the lacrimal sac. This forms part of the lacrimal apparatus that drains lacrimal fluid from the surface of the eye to the nasal cavity.
The lacrimal sac or lachrymal sac is the upper dilated end of the nasolacrimal duct, and is lodged in a deep groove formed by the lacrimal bone and frontal process of the maxilla. It connects the lacrimal canaliculi, which drain tears from the eye's surface, and the nasolacrimal duct, which conveys this fluid into the nasal cavity. Lacrimal sac occlusion leads to dacryocystitis.
Epicanthoplasty is a rare eye surgery to modify the epicanthal folds. It can be a challenging procedure because the epicanthal folds overlay the lacrimal canaliculi . Although an epicanthic fold can also be associated with a less prominent upper eyelid crease, the two features are distinct; a person may have both epicanthal folds and an upper eyelid crease, one and not the other, or neither. Single eyelids are reshaped using East Asian blepharoplasty.
The lacrimal punctum or lacrimal point, is a minute opening on the summits of the lacrimal papillae, seen on the margins of the eyelids at the lateral extremity of the lacrimal lake. There are two lacrimal puncta in the medial (inside) portion of each eyelid. Normally, the puncta dip into the lacrimal lake.
The lacrimal lake is the pool of tears in the lower conjunctival cul-de-sac, which drains into the opening of the tear drainage system. The volume of the lacrimal lake has been estimated to be between 7 and 10 μL.
Punctum, plural puncta, adjective punctate, is an anatomical term for a sharp point or tip. It may also refer to:
Oculoplastics, or oculoplastic surgery, includes a wide variety of surgical procedures that deal with the orbit, eyelids, tear ducts, and the face. It also deals with the reconstruction of the eye and associated structures.
Epiphora is an overflow of tears onto the face, other than caused by normal crying. It is a clinical sign or condition that constitutes insufficient tear film drainage from the eyes, in that tears will drain down the face rather than through the nasolacrimal system.
Antoine Ferrein was a French anatomist who was a native of Frespech, which today is a commune in the arrondissement of Villeneuve-sur-Lot. He was a professor at the Collège Royal in Paris, and in 1742 became a member of the Académie des sciences.
Hidrocystoma is an adenoma of the sweat glands.
Punctoplasty is a surgical procedure to restore proper drainage of tears when the lacrimal punctum becomes blocked in one or both eyes.
The accessory visual structures are the protecting and supporting structures (adnexa) of the eye, including the eyebrow, eyelids, and lacrimal apparatus. The eyebrows, eyelids, eyelashes, lacrimal gland and drainage apparatus all play a crucial role with regards to globe protection, lubrication, and minimizing the risk of ocular infection. The adnexal structures also help to keep the cornea moist and clean.
Nasolacrimal duct obstruction is the obstruction of the nasolacrimal duct and may be either congenital or acquired. Obstruction of the nasolacrimal duct leads to the excess overflow of tears called epiphora.
