The following is a partial list of the "A" codes for Medical Subject Headings (MeSH), as defined by the

United States National Library of Medicine The United States National Library of Medicine (NLM), operated by the United States federal government, is the world's largest medical library. Located in Bethesda, Maryland, the NLM is an institute within the National Institutes of Health. Its ...

(NLM). This list continues the information at List of MeSH codes (A08). Codes following these are found at

List of MeSH codes (A10) The following is a partial list of the "A" codes for Medical Subject Headings (MeSH), as defined by the United States National Library of Medicine (NLM). This list continues the information at List of MeSH codes (A09). Codes following these are ...

. For other MeSH codes, see

List of MeSH codes The following is a list of the codes for MeSH (Medical Subject Headings), a comprehensive controlled vocabulary for the purpose of index (publishing), indexing journal articles and books in the life sciences. It is a product of the United States ...

. The source for this content is the set o
2006 MeSH Trees
from the NLM.

–
sense organs A sense is a biological system used by an organism for sensation, the process of gathering information about the world through the detection of stimuli. (For example, in the human body, the brain which is part of the central nervous system re ...

–
ear An ear is the organ that enables hearing and, in mammals, body balance using the vestibular system. In mammals, the ear is usually described as having three parts—the outer ear, the middle ear and the inner ear. The outer ear consists of ...

– ear, external

* – ear canal * – ear cartilages * –

tympanic membrane In the anatomy of humans and various other tetrapods, the eardrum, also called the tympanic membrane or myringa, is a thin, cone-shaped membrane that separates the external ear from the middle ear. Its function is to transmit sound from the a ...

– ear, middle

* –

ear ossicles The ossicles (also called auditory ossicles) are three bones in either middle ear that are among the smallest bones in the human body. They serve to transmit sounds from the air to the fluid-filled labyrinth (cochlea). The absence of the auditory ...

* –

incus The ''incus'' (plural incudes) or anvil is a bone in the middle ear. The anvil-shaped small bone is one of three ossicles in the middle ear. The ''incus'' receives vibrations from the ''malleus'', to which it is connected laterally, and transmit ...

* –

malleus The malleus, or hammer, is a hammer-shaped small bone or ossicle of the middle ear. It connects with the incus, and is attached to the inner surface of the eardrum. The word is Latin for 'hammer' or 'mallet'. It transmits the sound vibrations f ...

* –

stapes The ''stapes'' or stirrup is a bone in the middle ear of humans and other animals which is involved in the conduction of sound vibrations to the inner ear. This bone is connected to the oval window by its annular ligament, which allows the foo ...

* – eustachian tube * – glomus tympanicum * – stapedius * –

tensor tympani The tensor tympani is a muscle within the middle ear, located in the bony canal above the bony part of the auditory tube, and connects to the malleus bone. Its role is to dampen loud sounds, such as those produced from chewing, shouting, or th ...

– ear, inner

* –

cochlea The cochlea is the part of the inner ear involved in hearing. It is a spiral-shaped cavity in the bony labyrinth, in humans making 2.75 turns around its axis, the modiolus. A core component of the cochlea is the Organ of Corti, the sensory or ...

* –

basilar membrane The basilar membrane is a stiff structural element within the cochlea of the inner ear which separates two liquid-filled tubes that run along the coil of the cochlea, the scala media and the scala tympani. The basilar membrane moves up and down ...

* – cochlear aqueduct * –

cochlear duct The cochlear duct (bounded by the scala media) is an endolymph filled cavity inside the cochlea, located between the tympanic duct and the vestibular duct, separated by the basilar membrane and the vestibular membrane (Reissner's membrane) re ...

* –

stria vascularis The stria vascularis of the cochlear duct is a capillary loop in the upper portion of the spiral ligament (the outer wall of the cochlear duct). It produces endolymph for the scala media in the cochlea. Structure The stria vascularis is part o ...

* –

tectorial membrane The tectoria membrane (TM) is one of two acellular membranes in the cochlea of the inner ear, the other being the basilar membrane (BM). "Tectorial" in anatomy means forming a cover. The TM is located above the spiral limbus and the spiral organ ...

* –

organ of corti The organ of Corti, or spiral organ, is the receptor organ for hearing and is located in the mammalian cochlea. This highly varied strip of epithelial cells allows for transduction of auditory signals into nerve impulses' action potential. Transd ...

* –

hair cells Hair cells are the sensory receptors of both the auditory system and the vestibular system in the ears of all vertebrates, and in the lateral line organ of fishes. Through mechanotransduction, hair cells detect movement in their environment. ...

* – hair cells, inner * – hair cells, outer * – labyrinth supporting cells * –

round window The round window is one of the two openings from the middle ear into the inner ear. It is sealed by the secondary tympanic membrane (round window membrane), which vibrates with opposite phase to vibrations entering the inner ear through the oval ...

* –

scala tympani The tympanic duct or scala tympani is one of the perilymph-filled cavities in the inner ear of humans. It is separated from the cochlear duct by the basilar membrane, and it extends from the round window to the helicotrema, where it continues as ...

* –

spiral ganglion The spiral (cochlear) ganglion is a group of neuron cell bodies in the modiolus, the conical central axis of the cochlea. These bipolar neurons innervate the hair cells of the organ of Corti. They project their axons to the ventral and dorsal co ...

* – spiral lamina * –

semicircular canals The semicircular canals or semicircular ducts are three semicircular, interconnected tubes located in the innermost part of each ear, the inner ear. The three canals are the horizontal, superior and posterior semicircular canals. Structure The ...

* – hair cells, vestibular * –

vestibule of the ear The vestibule is the central part of the bony labyrinth in the inner ear, and is situated medial to the eardrum, behind the cochlea, and in front of the three semicircular canals. The name comes from the Latin ', literally an entrance hall. Stru ...

* –

oval window The oval window (or ''fenestra vestibuli'' or ''fenestra ovalis'') is a membrane-covered opening from the middle ear to the cochlea of the inner ear. Vibrations that contact the tympanic membrane travel through the three ossicles and into the in ...

* – saccule and utricle * – acoustic maculae * – hair cells, vestibular * – otolithic membrane * –

vestibular aqueduct At the hinder part of the medial wall of the vestibule is the orifice of the vestibular aqueduct, which extends to the posterior surface of the petrous portion of the temporal bone. It transmits a small vein, and contains a tubular prolongation ...

* –

endolymphatic duct From the posterior wall of the saccule a canal, the endolymphatic duct, is given off; this duct is joined by the ductus utriculosaccularis, and then passes along the aquaeductus vestibuli and ends in a blind pouch (endolymphatic sac) on the poster ...

* –

endolymphatic sac From the posterior wall of the saccule a canal, the endolymphatic duct, is given off; this duct is joined by the utriculosaccular duct, and then passes along the vestibular aqueduct and ends in a blind pouch, the endolymphatic sac, on the poster ...

– eye

– anterior eye segment

* –

anterior chamber The anterior chamber ( AC) is the aqueous humor-filled space inside the eye between the iris and the cornea's innermost surface, the endothelium. Hyphema, anterior uveitis and glaucoma are three main pathologies in this area. In hyphema, blood f ...

* –

aqueous humor The aqueous humour is a transparent water-like fluid similar to plasma, but containing low protein concentrations. It is secreted from the ciliary body, a structure supporting the lens of the eyeball. It fills both the anterior and the posteri ...

* – endothelium, corneal * –

cornea The cornea is the transparent front part of the eye that covers the iris, pupil, and anterior chamber. Along with the anterior chamber and lens, the cornea refracts light, accounting for approximately two-thirds of the eye's total optical ...

* – bowman membrane * –

corneal stroma The stroma of the cornea (or substantia propria) is a fibrous, tough, unyielding, perfectly transparent and the thickest layer of the cornea of the eye. It is between Bowman's membrane anteriorly, and Descemet's membrane posteriorly. At its cent ...

* – descemet membrane * – endothelium, corneal * – epithelium, corneal * – limbus corneae * –

trabecular meshwork The trabecular meshwork is an area of tissue in the eye located around the base of the cornea, near the ciliary body, and is responsible for draining the aqueous humor from the eye via the anterior chamber (the chamber on the front of the ...

–
conjunctiva The conjunctiva is a thin mucous membrane that lines the inside of the eyelids and covers the sclera (the white of the eye). It is composed of non-keratinized, stratified squamous epithelium with goblet cells, stratified columnar epithelium ...

–
eyelids An eyelid is a thin fold of skin that covers and protects an eye. The levator palpebrae superioris muscle retracts the eyelid, exposing the cornea to the outside, giving vision. This can be either voluntarily or involuntarily. The human eye ...

* –

eyelashes An eyelash (also called lash) (Latin: ''Cilia'') is one of the hairs that grows at the edge of the eyelids. It grows in one layer on the edge of the upper and lower eyelids. Eyelashes protect the eye from debris, dust, and small particles and p ...

* –

meibomian glands Meibomian glands (also called tarsal glands, palpebral glands, and tarsoconjunctival glands) are sebaceous glands along the rims of the eyelid inside the tarsal plate. They produce meibum, an oily substance that prevents evaporation of the eye' ...

–
lacrimal apparatus The lacrimal apparatus is the physiological system containing the orbital structures for tear production and drainage.Cassin, B. and Solomon, S. ''Dictionary of Eye Terminology''. Gainesville, Florida: Triad Publishing Company, 1990. It consist ...

* –

nasolacrimal duct The nasolacrimal duct (also called the tear 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. T ...

– lens, crystalline

* – lens capsule, crystalline * – lens cortex, crystalline * – lens nucleus, crystalline

– oculomotor muscles

– pigment epithelium of eye

–
retina The retina (from la, rete "net") is the innermost, light-sensitive layer of tissue of the eye of most vertebrates and some molluscs. The optics of the eye create a focused two-dimensional image of the visual world on the retina, which then ...

* – amacrine cells * – blood-retinal barrier * – fundus oculi * –

macula lutea The macula (/ˈmakjʊlə/) or macula lutea is an oval-shaped pigmented area in the center of the retina of the human eye and in other animals. The macula in humans has a diameter of around and is subdivided into the umbo, foveola, foveal av ...

* –

fovea centralis The fovea centralis is a small, central pit composed of closely packed cones in the eye. It is located in the center of the macula lutea of the retina. The fovea is responsible for sharp central vision (also called foveal vision), which is ne ...

* –

optic disk Optics is the branch of physics that studies the behaviour and properties of light, including its interactions with matter and the construction of instruments that use or detect it. Optics usually describes the behaviour of visible, ultravio ...

* – photoreceptors * – photoreceptors, invertebrate * – photoreceptors, vertebrate * – rods * –

cones A cone is a three-dimensional geometric shape that tapers smoothly from a flat base (frequently, though not necessarily, circular) to a point called the apex or vertex. A cone is formed by a set of line segments, half-lines, or lines conn ...

* – rod outer segments * –

retinal bipolar cells As a part of the retina, bipolar cells exist between photoreceptors ( rod cells and cone cells) and ganglion cells. They act, directly or indirectly, to transmit signals from the photoreceptors to the ganglion cells. Structure Bipolar cells are ...

* –

retinal ganglion cells A retinal ganglion cell (RGC) is a type of neuron located near the inner surface (the ganglion cell layer) of the retina of the eye. It receives visual information from photoreceptors via two intermediate neuron types: bipolar cells and retina ...

* – retinal horizontal cells

– sclera

–
uvea The uvea (; Lat. ''uva'', "grape"), also called the ''uveal layer'', ''uveal coat'', ''uveal tract'', ''vascular tunic'' or ''vascular layer'' is the pigmented middle of the three concentric layers that make up an eye. History and etymolog ...

* – blood-aqueous barrier * – choroid * –

bruch membrane Bruch's membrane is the innermost layer of the choroid of the eye. It is also called the ''vitreous lamina'' or ''Membrane vitriae'', because of its glassy microscopic appearance. It is 2–4 μm thick. Layers Bruch's membrane consists of five ...

* –

ciliary body The ciliary body is a part of the eye that includes the ciliary muscle, which controls the shape of the lens, and the ciliary epithelium, which produces the aqueous humor. The aqueous humor is produced in the non-pigmented portion of the ciliar ...

* –

iris Iris most often refers to: *Iris (anatomy), part of the eye *Iris (mythology), a Greek goddess * ''Iris'' (plant), a genus of flowering plants * Iris (color), an ambiguous color term Iris or IRIS may also refer to: Arts and media Fictional ent ...

* –

pupil The pupil is a black hole located in the center of the Iris (anatomy), iris of the Human eye, eye that allows light to strike the retina.Cassin, B. and Solomon, S. (1990) ''Dictionary of Eye Terminology''. Gainesville, Florida: Triad Publishing ...

–
vitreous body The vitreous body (''vitreous'' meaning "glass-like"; , ) is the clear gel that fills the space between the lens and the retina of the eyeball (the vitreous chamber) in humans and other vertebrates. It is often referred to as the vitreous hu ...

–
nose A nose is a protuberance in vertebrates that houses the nostrils, or nares, which receive and expel air for respiration alongside the mouth. Behind the nose are the olfactory mucosa and the sinuses. Behind the nasal cavity, air next passes ...

–
olfactory mucosa The olfactory mucosa is located in the upper region of the nasal cavity and is made up of the olfactory epithelium and the underlying lamina propria, connective tissue containing fibroblasts, blood vessels, Bowman's glands and bundles of fine ax ...

* –

olfactory receptor neurons An olfactory receptor neuron (ORN), also called an olfactory sensory neuron (OSN), is a sensory neuron within the olfactory system. Structure Humans have between 10 and 20 million olfactory receptor neurons (ORNs). In vertebrates, ORNs are b ...

–
vomeronasal organ The vomeronasal organ (VNO), or Jacobson's organ, is the paired auxiliary olfactory (smell) sense organ located in the soft tissue of the nasal septum, in the nasal cavity just above the roof of the mouth (the hard palate) in various tetrapods. T ...

–
taste buds Taste buds contain the taste receptor cells, which are also known as gustatory cells. The taste receptors are located around the small structures known as papillae found on the upper surface of the tongue, soft palate, upper esophagus, the che ...

---- The list continues at

. {{MeSH codes A09

– sense organs A sense is a biological system used by an organism for sensation, the process of gathering information about the world through the detection of stimuli. (For example, in the human body, the brain which is part of the central nervous system re ...

– ear An ear is the organ that enables hearing and, in mammals, body balance using the vestibular system. In mammals, the ear is usually described as having three parts—the outer ear, the middle ear and the inner ear. The outer ear consists of ...

– ear, external

– ear, middle

– ear, inner

– eye

– anterior eye segment

– conjunctiva The conjunctiva is a thin mucous membrane that lines the inside of the eyelids and covers the sclera (the white of the eye). It is composed of non-keratinized, stratified squamous epithelium with goblet cells, stratified columnar epithelium ...

– eyelids An eyelid is a thin fold of skin that covers and protects an eye. The levator palpebrae superioris muscle retracts the eyelid, exposing the cornea to the outside, giving vision. This can be either voluntarily or involuntarily. The human eye ...

– lacrimal apparatus The lacrimal apparatus is the physiological system containing the orbital structures for tear production and drainage.Cassin, B. and Solomon, S. ''Dictionary of Eye Terminology''. Gainesville, Florida: Triad Publishing Company, 1990. It consist ...

– lens, crystalline

– oculomotor muscles

– pigment epithelium of eye

– retina The retina (from la, rete "net") is the innermost, light-sensitive layer of tissue of the eye of most vertebrates and some molluscs. The optics of the eye create a focused two-dimensional image of the visual world on the retina, which then ...

– sclera

– uvea The uvea (; Lat. ''uva'', "grape"), also called the ''uveal layer'', ''uveal coat'', ''uveal tract'', ''vascular tunic'' or ''vascular layer'' is the pigmented middle of the three concentric layers that make up an eye. History and etymolog ...

– vitreous body The vitreous body (''vitreous'' meaning "glass-like"; , ) is the clear gel that fills the space between the lens and the retina of the eyeball (the vitreous chamber) in humans and other vertebrates. It is often referred to as the vitreous hu ...

– nose A nose is a protuberance in vertebrates that houses the nostrils, or nares, which receive and expel air for respiration alongside the mouth. Behind the nose are the olfactory mucosa and the sinuses. Behind the nasal cavity, air next passes ...

– olfactory mucosa The olfactory mucosa is located in the upper region of the nasal cavity and is made up of the olfactory epithelium and the underlying lamina propria, connective tissue containing fibroblasts, blood vessels, Bowman's glands and bundles of fine ax ...

– vomeronasal organ The vomeronasal organ (VNO), or Jacobson's organ, is the paired auxiliary olfactory (smell) sense organ located in the soft tissue of the nasal septum, in the nasal cavity just above the roof of the mouth (the hard palate) in various tetrapods. T ...

– taste buds Taste buds contain the taste receptor cells, which are also known as gustatory cells. The taste receptors are located around the small structures known as papillae found on the upper surface of the tongue, soft palate, upper esophagus, the che ...