為什麼哭的同時會流鼻涕？

12-21

那個就是眼淚，當然也可能混著鼻涕。

眼淚從淚腺分泌（lacrimal gland），又經上下兩個淚點（lacrimal punctum）引流進入淚管，流入淚囊，然後經過鼻淚管（nasolacrimal duct）就從下鼻甲的開口處進入鼻腔了。

哭的時候眼淚很多，所以淚液引流進鼻腔的會很明顯。大量的淚液也連帶著把鼻粘膜的附近的分泌也帶出來了。

圖片出處：http://www.medfriendly.com

同意我以前也想過這個問題，想出的主要原因也是這個解釋。當然還有很多小因素，任何一個生理反應都是多因素影響下產生的

Drainage System (淚排出系統)

Drainage of tears from the eyelids into the nose requires a patent drainage
system (Fig. 23) comprising the puncta, canaliculi, lacrimal sac, and nasolacrimal duct, proper
positioning of the eyelids against the globe, and an intact
lacrimal pump function.42

,

43 If any of these components fails, epiphora will result.

Fig. 23. Lacrimal drainage system. A. Measurements. B. Valves of the lacrimal sac and nasolacrimal duct. (A from Jones LT, Wobig JL: Surgery of the Eyelids and Lacrimal System. Birmingham, Aesculapius, 1976. B from Bergin DJ: Anatomy of the eyelids, lacrimal system, and orbit. In
McCord CD, Tanenbaum M, Nunery WR [eds]: Oculoplastic Surgery [3rd
ed]. New York, Raven Press, 1995).

The puncta are defined as the openings of the canaliculi onto the eyelid
margin (see Fig. 6). Each punctum measures about 0.3 mm in diameter and is found 0.5 to 1.0 mm
medial to the end of the tarsal plate. The upper punctum is usually
found slightly nasal to the lower punctum, each measuring 6 mm and 6.5 mm
from the medial commissure, respectively. Thus, the puncta do
not overlap each other during eyelid blink. Peripunctal tissue is avascular
and rich in elastic tissue. This last point is documented clinically
when observing the rapid collapse of the puncta in younger patients
immediately after probing.

The canaliculi begin anatomically at the puncta. The vertical portion measures
about 2 mm, with an ampulla (2.5 mm in diameter) forming just
beneath the punctal opening. The horizontal portion measures 8 mm in length, surrounded
by the medial portions of the muscle of Riolan (also
known as Horner"s muscle, an extension of the pretarsal orbicularis) and
traveling through the fiber network of the medial canthal tendon. The
diameter of each canaliculus is only 1 mm. In more than 90% of
individuals, the canaliculi join to form a common canaliculus known
as the ampulla of Maier, which then enters the lacrimal sac at the common
internal punctum. The common internal punctum forms the first major
valve of the lacrimal system, the valve of Rosenmuller, and acts to
prevent reflux of tears back into the canaliculi during lacrimal pump
function.

The lacrimal sac is found within its bony fossa, formed by the anterior
and posterior lacrimal crests (see Fig. 7A and B). It measures 12 to 15 mm in length and has strong attachments over its
lateral surface from the medial canthal tendon and fibers of the orbicularis (Horner"s
and Jones" muscles). The portion of the sac found
above the medial canthal tendon is defined as the fundus, measuring 3 to 5 mm
in height. Inferiorly, the sac opens into the nasolacrimal
duct at the lacrimal ostium. (Note the proximity of the inferior oblique
muscle origin, an important consideration during surgery of the lacrimal
sac.) The pseudostratified nonkeratinized columnar epithelium of
the lacrimal sac is thrown into numerous folds that form a screwlike
passageway for tear outflow. Although each fold has been given various
eponyms (see Fig. 23B), these are not important to remember; rather, understand that the folds
as a unit perform the important function of efficiently driving tear
flow in a unilateral direction down the nasolacrimal duct. The walls
of the sac are rich in elastic tissue, thereby allowing for the constant
collapse and reformation of the sac during the blink reflex.

The nasolacrimal duct travels within its canal for 12 mm through the nasofrontal
process of the maxillary bone, opening intranasally into the
inferior meatus, found just beneath the inferior turbinate. The opening
of the nasolacrimal duct is about 16 to 25 mm posterior to the tip
of the nose in adults, and about half that distance in children. The duct
travels in a posterior and lateral direction,24 angulating 15° and 5°, respectively. As already noted, the inferior
opening of the duct is defined as the valve of Hasner.

The lacrimal pump mechanism is described elsewhere. In addition to the
dynamic process of the pump, gravity also assists in tear outflow.

SECRETORY SYSTEM

The aqueous portion of the tear film is produced by several glandular units found within the eyelids and anterior orbit.

Considerable controversy exists regarding the innervation and contribution of each set of glands.

One theory put forth by Jones defines the main lacrimal gland as a 「reflex」secretor (i.e., dependent on neural stimulation for tear production), whereas the accessory lacrimal glands found along the inner aspect of the eyelids are called 「basic」secretors, producing tears at a constant, unchanging rate. This theory forms the basis for the Schirmer tests of tear production.

In the fully developed orbit, the lacrimal gland is normally impalpable and is situated in a small fossa behind the superotemporal orbital rim. It is not an encapsulated structure but rather is an aggregated collection of lobules of secretory tissue set in the superotemporal orbital fat, with interlobular ducts converging into the main excretory ducts in the superotemporal fornix. Within the secretory acini are located inner columnar to cuboidal zymogen-bearing cells, on the outer aspect of which are applied contractile myoepithelial cells. Mucus-producing elements are not present. Myoepithelial cells are not present in the terminal intralobular ductules or in the interlobular ducts. The acinar elements are not capable of regenerating after inflammatory insults, and the regenerative capacity of the gland resides in the terminal ductules.

Lymphoid tissue is present in the substantia propria of the conjunctiva, and lymphocytes and plasma cells are lightly dispersed among the secretory acini of the lacrimal gland, but the deep orbital tissue is devoid of a standing population of lymphoid cells. Based on a study of the immunoarchitecture of the lacrimal gland using monoclonal antibodies as markers, plasma cells are the predominant mononuclear cell type, making up 54%, and are located in the interstitium of the gland. Immunoglobulin A (IgA) vastly predominates over other immunoglobulin types; lymphocytes of the substantia propria of the conjunctiva and of the lacrimal gland secrete IgA, which has a secretory piece added to it as it moves across the ducts of the gland or the conjunctival epithelium. T cells make up 40% of all mononuclear cells, with T8 suppressor/cytotoxic cells outnumbering T4 helper cells. Occasional small lymphoid aggregates without germinal centers may also be seen at the juncture of intralobular and interlobular ducts, in which T4 helper cells predominate and a smattering of B cells are found. Lymphoid tumors, representing reactive hyperplasias and true lymphomas, consequently are derived from blood-borne lymphocytes that emigrate from the orbital vascular system into the orbital connective tissues, generally into the orbital fat. To date, there are no identifiable endothelial-lined lymphatics within the orbit, although the lacrimal gland itself contains lymphatic channels that drain to the preauricular and cervical nodes. The fact that the lacrimal gland has a standing population of lymphocytes and plasma cells—which are not, however, organized into lymph nodes (as may be seen in the parotid gland)—may explain the relative frequency of the development of idiopathic dacryoadenitis and lymphoid tumors of the gland. Inflammatory pseudotumors, lymphoid tumors, inflammations such as sarcoidosis and Sj?gren syndrome, and epithelial tumors are the main types of pathology that arise from or involve the lacrimal gland.

The main lacrimal gland is split into two lobes, the palpebral and the orbital, by the lateral horn of the levator aponeurosis2 (Fig. 24). The palpebral lobe measures about one-third the volume of the orbital lobe, and its subconjunctival location is easily identified during slit-lamp examination. The orbital lobe lies within its fossa, a concavity found within the lateral portion of the orbital roof. Fibrous septa known as Sommering"s ligaments run from the gland to attach it more firmly to the periosteum of the lacrimal gland fossa. Whitnall"s ligament also adds support for lacrimal gland suspension.30 (The lacrimal sac fossa is distinctly separate from the lacrimal gland fossa; the term 「lacrimal fossa」is discouraged because it is confusing in its nonspecificity.) The shape of the orbital lobe is rather like that of a pancake (see Fig. 21B). The orbital lobe is usually limited to its fossa, but it is not uncommon to encounter posterior tails of lacrimal gland tissue traveling toward the orbital apex on routine CT/MRI studies.1 Likewise, the palpebral lobe may extend as inferiorly as the lateral canthal tendon in some individuals.31

Fig. 24. The lateral horn of the levator aponeurosis splits the lacrimal gland into the orbital and palpebral lobes as it sweeps laterally to insert into the lateral canthal tendon of the eyelid. (Zide BM, Jelks GW: Surgical Anatomy of the Orbit, p 35. New York, Raven Press, 1985)

Tear outflow passes from the orbital to the palpebral lobe through the levator aponeurosis; aggressive dissection in this area during levator surgery can thus damage the outflow mechanism. The palpebral lobe opens into the superolateral conjunctival fornix through 10 to 12 ductules. Innervation to the lacrimal gland remains controversial32 but can be summarized succinctly as sensory innervation from the lacrimal nerve (V-1) and parasympathetic innervation from the pterygopalatine ganglion.23 The role of sympathetic innervation is not completely understood.

The accessory lacrimal glands or basic secretors are usually grouped as the glands of Krause, found along the conjunctival fornices, and the glands of Wolfring, found along the superior tarsal border of the upper eyelid. The glands of Wolfring may be injured during ptosis repair by a posterior approach. The glands of Popov are located within the substance of the caruncle.

Two additional components of the tear film are mentioned briefly. The outer lipid layer is produced by the meibomian glands, which form excavations within the tarsus and open at the eyelid margin (and by minor contributions from the glands of Zeis and Moll of the eyelash follicle). The inner mucin layer is made by the conjunctival goblet cells.

那為什麼鼻涕是粘的，怎麼不是水呢？

鼻淚管。