The lacrimal bones are two small and fragile bones of the facial skeleton; they are roughly the size of the little fingernail and situated at the front part of the medial wall of the orbit. They each have two surfaces and four borders. Several bony landmarks of the lacrimal bones function in the process of lacrimation. Specifically, the lacrimal bones help form the nasolacrimal canal necessary for tear translocation. A depression on the anterior inferior portion of one bone, the lacrimal fossa, houses the membranous lacrimal sac. Tears, from the lacrimal glands, collect in this sac during excessive lacrimation. The fluid then flows through the nasolacrimal duct and into the nasopharynx. This drainage results in what is commonly referred to a runny nose during excessive crying or tear production. Injury or fracture of the lacrimal bone can result in posttraumatic obstruction of the lacrimal pathways.
The inferior nasal concha is one of the three paired nasal conchae in the nose. It extends horizontally along the lateral wall of the nasal cavity and consists of a lamina of spongy bone, curled upon itself like a scroll,. The inferior nasal conchae are considered a pair of facial bones. As the air passes through the turbinates, the air is churned against these mucosa-lined bones in order to receive warmth, moisture and cleansing. Superior to inferior nasal concha are the middle nasal concha and superior nasal concha which both arise from the ethmoid bone, of the cranial portion of the skull. Hence, these two are considered as a part of the cranial bones.
In anatomy, the orbit is the cavity or socket/hole of the skull in which the eye and its appendages are situated. "Orbit" can refer to the bony socket, or it can also be used to imply the contents. In the adult human, the volume of the orbit is about 28 millilitres, of which the eye occupies 6.5 ml. The orbital contents comprise the eye, the orbital and retrobulbar fascia, extraocular muscles, cranial nerves II, III, IV, V, and VI, blood vessels, fat, the lacrimal gland with its sac and duct, the eyelids, medial and lateral palpebral ligaments, cheek ligaments, the suspensory ligament, septum, ciliary ganglion and short ciliary nerves.
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 ethmoidal labyrinth or lateral mass of the ethmoid bone consists of a number of thin-walled cellular cavities, the ethmoid air cells, arranged in three groups, anterior, middle, and posterior, and interposed between two vertical plates of bone; the lateral plate forms part of the orbit, the medial plate forms part of the nasal cavity. In the disarticulated bone many of these cells are opened into, but when the bones are articulated, they are closed in at every part, except where they open into the nasal cavity.
The maxillary hiatus is the opening of a maxillary sinus into the middle nasal meatus of the nasal cavity. It is situated superoposteriorly upon the lateral nasal wall, opening into the nasal cavity at the posterior portion of the ethmoidal infundibulum. Its opening in the maxillary sinus is present upon the superior part of the medial wall of the sinus near the roof of the sinus; because of the position, gravity cannot drain the maxillary sinus contents when the head is erect.
The lacrimal apparatus is the physiological system containing the orbital structures for tear production and drainage.
It consists of:
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.
On the nasal surface of the body of the maxilla, in front of the opening of the sinus is a deep groove, the lacrimal groove, which is converted into the nasolacrimal canal, by the lacrimal bone and inferior nasal concha; this canal opens into the inferior meatus of the nose and transmits the nasolacrimal duct.
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 medial palpebral arteries are arteries of the head that contribute arterial blood supply to the eyelids. They are derived from the ophthalmic artery; a single medial palpebral artery issues from the ophthalmic artery before splitting into a superior and an inferior medial palpebral artery, each supplying one eyelid.
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.
Dacryocystorhinostomy (DCR) is a surgical procedure to restore the flow of tears into the nose from the lacrimal sac when the nasolacrimal duct does not function.
Dacryocystitis is an infection of the lacrimal sac, secondary to obstruction of the nasolacrimal duct at the junction of the lacrimal sac. The term derives from Greek dákryon 'tear' cysta 'sac' and -itis 'inflammation'. It causes pain, redness, and swelling over the inner aspect of the lower eyelid and epiphora. When nasolacrimal duct obstruction is secondary to a congenital barrier it is referred to as dacryocystocele. It is most commonly caused by Staphylococcus aureus and Streptococcus pneumoniae. The most common complication is corneal ulceration, frequently in association with S. pneumoniae. The mainstays of treatment are oral antibiotics, warm compresses, and relief of nasolacrimal duct obstruction by dacryocystorhinostomy.
The following outline is provided as an overview of and topical guide to human anatomy:
Dacryocystocele (Dacryocystitis) or timo cyst is a benign, bluish-gray mass in the inferomedial canthus that develops within a few days or weeks after birth. The uncommon condition forms as a result as a consequence of narrowing or obstruction of the nasolacrimal duct, usually during prenatal development. Nasolacrimal duct obstruction disrupts the lacrimal drainage system, eventually creating a swelling cyst in the lacrimal sac area by the nasal cavity. The location of the cyst can cause respiratory dysfunction, compromising the airway. The obstruction ultimately leads to epiphora, an abundance of tear production.
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 ducts and may be either congenital or acquired. Obstruction of the nasolacrimal ducts leads to the excess overflow of tears called epiphora.
In anatomy, the term nasal meatus can refer to any of the three meatuses (passages) through the skull's nasal cavity: the superior meatus, middle meatus, and inferior meatus.
Dacryoscintigraphy (DSG), also known as lacrimal scintigraphy, is a nuclear medicine technique for imaging the lacrimal apparatus. It is used to identify obstructions, for example in the lacrimal duct, nasal cavity or nasolacrimal duct.
