Cochlear duct Health Dictionary

The name applied to a passage leading from a gland into some hollow organ, or on to the surface of the body, by which the secretion of the gland is discharged: for example, the pancreatic duct and the bile duct opening into the duodenum, and the sweat ducts opening on the skin surface.... duct

A duct that goes through the nasolacrimal canal in the palatine bone of the SKULL. The duct drains the tears from the lacrimal (tear) glands into the NOSE.... nasolacrimal duct

See DUCTUS ARTERIOSUS.... patent ductus arteriosus

This is the bodies’ main lymph collecting vessel. It starts in the little collecting bladder in the abdomen (the cisterna chyli), moves up the center of the body in front of the spinal chord, alongside the esophagus and aorta to the neck, where it drains into the left subclavian vein. It drains the lymph from the entire body, except the head, right thorax and arm, which collects lymph separately and drains into the right subclavian vein. Lacking the ability to contract and expand, the thoracic duct relies on its valves and the kinetic energy of breathing and nearby arterial pumping to drain lymph upwards.... thoracic duct

The channel running from the gall-bladder (see LIVER) to the DUODENUM; carries BILE.... bile duct

The tube that runs from the gall-bladder (see LIVER) and joins up with the hepatic duct (formed from the bile ducts) to form the common BILE DUCT. The BILE produced by the liver cells is drained through this system and enters the small intestine to help in the digestion of food.... cystic duct

Any one of certain glands in the body the secretion of which goes directly into the bloodstream and so is carried to di?erent parts of the body. These glands – the pituitary, thyroid, parathyroid, adrenal and reproductive – are also known as the ENDOCRINE GLANDS. Some glands may be both duct glands and ductless glands. For example, the PANCREAS manufactures a digestive juice which passes by a duct into the small intestine. It also manufactures, by means of special cells, a substance called INSULIN which passes straight into the blood.... ductless gland

The blood vessel in the fetus through which blood passes from the pulmonary artery to the aorta, thereby bypassing the lungs, which do not function during intra-uterine life. (See CIRCULATORY SYSTEM OF THE BLOOD.) The ductus normally ceases to function soon after birth and within a few weeks is converted into a ?brous cord. Occasionally this obliteration does not occur: a condition known as patent ductus arteriosus. This is one of the more common congenital defects of the heart, and one which responds particularly well to surgical treatment. Closure of the duct can also be achieved in some cases by the administration of indomethacin. (See HEART, DISEASES OF.)... ductus arteriosus

A device used to treat profoundly deaf people who are not helped by hearing aids. A cochlear implant consists of tiny electrodes surgically implanted in the cochlea deep in the inner ear and a receiver that is embedded in the skull just behind and above the ear. A microphone, sound processor, and transmitter are worn externally. A cochlear implant does not restore normal hearing, but it enables patterns of sound to be detected. Combined with lip-reading, it may enable speech to be understood.... cochlear implant

A cochlear implant is an electronic device, inserted under a general anaesthetic, which stimulates the auditory system, restoring partial hearing in profound sensory deafness. Although there are many types of cochlear implant, they all consist of a microphone, a signal processor, a signal coupler (transmitter and receiver), and an array of electrodes. Most are multi-channel implants. The microphone and signal processor are worn outside the body, like a conventional hearing aid: they receive sound and convert it into an electronic signal which is transmitted through the skin to the receiver. Here the signal is transmitted to the array of electrodes which stimulates the cochlear nerve. Although cochlear implants do not provide normal hearing, most profoundly deaf patients who receive a cochlear implant are able to detect a variety of sounds, including environmental sounds and speech. The duration of hearing-loss and age at implantation are among the many factors which in?uence the results (see DEAFNESS).... cochlear implants

Ductus deferens, or VAS DEFERENS, is the tube which carries spermatozoa from the epidydimis to the seminal vesicles. (See TESTICLE.)... ductus deferens

The Mullerian and the Wol?an ducts are separate sets of primordia that transiently co-exist in embryos of both sexes (see EMBRYO). In female embryos the Mullerian ducts grow and fuse in the mid line, producing the FALLOPIAN TUBES, the UTERUS and the upper third of the VAGINA, whereas the Wol?an ducts regress. In the male the Wol?an ducts give rise to the VAS DEFERENS, the seminal vesicles and the EPIDIDYMIS, and the Mullerian ducts disappear. This phase of development requires a functioning testis (see TESTICLE) from which an inducer substance di?uses locally over the primordia to bring about the suppression of the Mullerian duct and the development of the Wol?an duct. In the absence of this substance, development proceeds along female lines regardless of the genetic sex.... mullerian ducts

the electrical potential generated by the cochlea in response to an acoustic stimulus. It can be detected by *auditory brainstem response audiometry or *electrocochleography and is useful in the diagnosis of *auditory neuropathy spectrum disorder.... cochlear microphonic

(acoustic nerve, auditory nerve) the nerve connecting the cochlea to the brain and therefore responsible for transmitting the nerve impulses relating to hearing. It forms part of the *vestibulocochlear nerve (cranial nerve VIII).... cochlear nerve

(DCIS) the earliest stage of breast cancer, detectable by mammography, which is confined to the lactiferous (milk) ducts of the breast. See carcinoma in situ.... ductal carcinoma in situ

pl. n. movements of one eye, i.e. adduction (rotation towards the nose), abduction (rotation towards the temple), elevation, depression, intorsion, and extorsion.... ductions

n. a small duct or channel.... ductule

n. a duct. The ductus deferens is the *vas deferens.... ductus

a blood vessel in the fetus that conveys oxygenated blood from the umbilical vein to the inferior vena cava and right atrium, where it passes through the *foramen ovale to the left atrium and left ventricle.... ductus venosus

a blind-ended duct that leads from the sacculus and joins a duct from the utriculus of the membranous *labyrinth of the ear.... endolymphatic duct

vaginal cysts, usually small, that arise from Gartner’s duct – remnants of the Wolffian duct (see mesonephros) in females. No treatment is necessary if the cysts are small and not symptomatic, but surgical *marsupialization or excision may be required if they are large and cause obstruction. [H. T. Gartner (1785–1827), Danish surgeon and anatomist]... gartner’s duct cysts

see bile duct.... hepatic duct

(paramesonephric duct) either of the paired ducts that form adjacent to the Wolffian ducts (see mesonephros) in the embryo. In the female these ducts develop into the Fallopian tubes, uterus, and part of the vagina. In the male anti-Müllerian hormone (AMH), produced by the fetal testis, arrests their development and by the tenth week of fetal life they have degenerated almost completely. In females AMH is produced by the ovary and levels are used as a measure of certain aspects of ovarian function, such as response to in vitro fertilization and assessing such conditions as polycystic ovary syndrome, premature ovarian failure, and intersex conditions in infants. [J. P. Müller (1801–58), German physiologist]... müllerian duct

see Müllerian duct.... paramesonephric duct

the long secretory duct of the *parotid salivary gland. [N. Stensen (1838–86), Danish physician]... stensen’s duct

the secretory duct of the submandibular *salivary gland. [T. Wharton (1614–73), English physician]... wharton’s duct

see mesonephros.... wolffian duct