Resource Library

m. abdo´minis  peritoneum.

m. adamanti´na  cuticula dentis.

m. adventi´tia  1. tunica adventitia.  2. decidua capsularis.

m. agni´na  amnion.

m. atlantooccipita´lis ante´rior  [TA]  anterior atlanto-occipital membrane: a single midline ligamentous structure that passes from the anterior arch of the atlas to the anterior margin of the foramen magnum, and corresponds in position with the anterior longitudinal ligament of the vertebral column. Called also anterior or deep atlantooccipital ligament and ligamentum atlantooccipitale anterius.

m. atlantooccipita´lis poste´rior  [TA]  posterior atlanto-occipital membrane: a single midline ligamentous structure that passes from the posterior arch of the atlas to the posterior margin of the foramen magnum, and corresponds in position with the ligamenta flava.

m. basa´lis  basement membrane.

m. basa´lis duc´tus semicircula´ris  basal membrane of semicircular duct: the basement membrane underlying the epithelium of a semicircular duct.

membra´nae cadu´cae  membranae deciduae.

m. capsula´ris  1. capsula articularis.  2. capsular membrane (def. 2).

m. choriocapilla´ris  lamina choroidocapillaris.

m. cricovoca´lis  conus elasticus.

membra´nae decid´uae  decidua.

m. epipapilla´ris  an abnormal fibrous membrane on the optic disk.

m. fibroelas´tica laryn´gis  [TA]  fibroelastic membrane of larynx: the fibroelastic layer beneath the mucous coat of the larynx, comprising the quadrangular membrane and the conus elasticus. See also intrinsic laryngeal ligaments, under ligament.

m. fibro´sa cap´sulae articula´ris  [TA]  fibrous membrane of articular capsule: the outer of the two layers of the articular capsule of a synovial joint, composed of dense white fibrous tissue; called also stratum fibrosum capsulae articularis [TA alternative].

m. flac´cida  pars flaccida membranae tympanicae.

m. fus´ca  lamina fusca sclerae.

m. germinati´va  blastoderm.

m. granulo´sa  layers of cuboidal epithelial cells at the periphery of an ovarian follicle and surrounding the antrum or fluid-filled cavity.

m. granulo´sa exter´na  the external granular layer of the retina.

m. granulo´sa inter´na  the internal granular layer of the retina.

m. hyaloi´dea  m. vitrea.

m. intercosta´lis exter´na  [TA]  external intercostal membrane: any of the aponeurotic bands parallel with, and perhaps replacing, the fibers of the external intercostal muscles in the spaces between the costal cartilages, from the ventral tips of the ribs medially to the sternum.

m. intercosta´lis inter´na  [TA]  internal intercostal membrane: any of the aponeurotic bands parallel with, and perhaps replacing, the fibers of the internal intercostal muscles in the spaces between the ribs, from the angles of the ribs medially to the vertebral column.

m. interos´sea antebra´chii  [TA] ,  m. interos´sea antibra´chii  interosseous membrane of forearm: a thin fibrous sheet that connects the bodies of the radius and ulna, passing from the interosseous margin of the radius to that of the ulna.

m. interos´sea cru´ris  [TA]  interosseous membrane of leg: a thin aponeurotic lamina attached to the interosseous margins of the tibia and fibula, deficient for a short distance at the proximal end of the bones; it separates the muscles on the anterior and posterior parts of the leg.

m. li´mitans  1. one of the limiting membranes of the retina; see external and internal limiting membrane (def. 1), under membrane.  2. the limiting membrane of glia fibrils and perivascular feet separating the parenchyma of the central nervous system from the pia and blood vessels. It is sometimes considered together with the pia mater as the pia-glia.

m. muco´sa vesi´cae fel´leae  tunica mucosa vesicae biliaris.

m. nic´titans  1. plica semilunaris conjunctivae.  2. nictitating membrane.

m. obturato´ria  [TA]  obturator membrane: a strong membrane that fills the obturator foramen except superiorly at the obturator groove, where a deficiency is left, the obturator canal.

m. perfora´ta  a term sometimes used to designate the first appearance of dentin in the fetus, manifested as a thick limiting line between the ameloblasts and odontoblasts.

m. perine´i  [TA]  membrane of perineum: the triangular fibrous membrane stretched horizontally between the ischiopubic rami, attached at its base to the perineal body; its apex thickens to form the transverse perineal ligament. Called also perineal membrane and inferior fascia of urogenital diaphragm.

m. pituito´sa  tunica mucosa nasi.

m. pro´pria  lamina propria mucosae.

m. pro´pria duc´tus semicircula´ris  proper membrane of semicircular duct: the outer, loose, connective tissue layer of a semicircular duct.

m. pupilla´ris  [TA]  pupillary membrane: the portion of the tunica vasculosa lentis that is in front of the pupil; it is a mesodermal layer attached to the rim or front of the iris during embryonic development, sometimes persisting in the adult. Called also Wachendorf's membrane.

m. quadrangula´ris  [TA]  quadrangular membrane: the upper part of the fibroelastic membrane of the larynx.

m. reticula´ris or´gani spira´lis  [TA] ,  m. reticula´ta  reticular membrane of spiral organ: a netlike membrane over the spiral organ; the free ends of the outer hair cells pass through its apertures. Called also reticular lamina.

m. ruyschia´na  Ruysch's membrane.

m. saccifor´mis  the synovial membrane of the inferior radioulnar articulation.

m. sero´sa  1. tunica serosa.  2. chorion.

m. seroti´na  decidua basalis.

m. spira´lis duc´tus cochlea´ris  TA alternative for paries tympanicus ductus cochlearis.

m. stapedia´lis  [TA] ,  m. stape´dis  stapedial membrane: a membrane filling the arch formed by the crura and base of the stapes.

m. statoconio´rum macula´rum  [TA]  statoconic membrane of maculae: the gelatinous membrane surmounting the maculae, containing the statoconia, and having special sensory hairs projecting into it.

m. ster´ni  [TA]  sternal membrane: the thick fibrous membrane that envelopes the sternum; it is formed by the intermingling of fibers of the radiate sternocostal ligaments, the periosteum, and the tendinous origin of the pectoralis major.

m. suprapleura´lis  [TA]  suprapleural membrane: the strengthened portion of the endothoracic fascia attached to the inner part of the first rib and the transverse process of the seventh cervical vertebra.

m. synovia´lis cap´sulae articula´ris  [TA]  synovial membrane of articular capsule: the inner of the two layers of the articular capsule of a synovial joint, composed of loose connective tissue and having a free smooth surface that lines the joint cavity. It secretes the synovial fluid. Called also stratum synoviale capsulae articularis [TA alternative].

m. synovia´lis infe´rior articulatio´nis temporomandibula´ris  [TA]  inferior synovial membrane of temporomandibular joint: the synovial membrane that lines the articular capsule of the joint below the articular disk.

m. synovia´lis supe´rior articulatio´nis temporomandibula´ris  [TA]  superior synovial membrane of temporomandibular joint: the synovial membrane that lines the articular capsule of the joint above the articular disk.

m. tecto´ria  [TA]  tectorial membrane: a strong fibrous band connected cranially with the basilar part of the occipital bone and caudally with the dorsal surface of the bodies of the second and third cervical vertebrae. It is actually the cranial prolongation of the deeper portion of the posterior longitudinal ligament of the vertebral column.

Click here to view image ■Membrana tectoria (tectorial membrane) in a posterior view of a dissection of the vertebral column. The vertebral arches, brainstem, and upper part of the spinal cord have been removed.

m. tecto´ria duc´tus cochlea´ris  [TA]  tectorial membrane of cochlear duct: a delicate gelatinous mass extending from the limbus and resting on the spiral organ of the ear and connected with the hairs of the hair cells; called also Corti's membrane.

m. ten´sa  pars tensa membranae tympanicae.

m. thyrohyoi´dea  [TA]  thyrohyoid membrane: a broad fibroelastic sheet attached above to the upper margin of the posterior surface of the hyoid bone and below to the upper border of the thyroid cartilage. See also extrinsic laryngeal ligaments, under ligament.

m. tym´pani  membrana tympanica.

m. tym´pani secunda´ria  m. tympanica secundaria.

m. tympa´nica  [TA]  tympanic membrane: the obliquely placed, thin membranous partition between the external acoustic meatus and the tympanic cavity. The greater portion, the pars tensa, is attached by a fibrocartilaginous ring to the tympanic plate of the temporal bone; the much smaller, triangular portion, the pars flaccida, is situated anterosuperiorly between the two mallear folds. Called also drumhead, drum, eardrum, and tympanum.

■Membrana tympanica (tympanic membrane).

■Otoscopic view of normal membrana tympanica (tympanic membrane).

m. tympa´nica secunda´ria  [TA]  secondary tympanic membrane: the membrane that closes in the fenestra cochlearis; called also Scarpa's membrane and membrane of round window.

m. vestibula´ris duc´tus cochlea´ris  TA alternative for paries vestibularis ductus cochlearis.

m. vi´brans  pars tensa membranae tympanicae.

m. vitelli´na  vitelline membrane.

m. vi´trea  [TA]  vitreous membrane: a delicate boundary layer investing the vitreous body of the eye; called also m. hyaloidea or hyaloid membrane.

abdominal m.  peritoneum.

accidental m.  false m.

adamantine m.  cuticula dentis.

alveolar-capillary m. ,  alveolocapillary m.  a thin tissue barrier between pulmonary alveoli and adjacent capillaries, the site of gas exchange between alveolar air and capillary blood. Called also alveolar-capillary or alveolocapillary barrier and blood-air or blood-gas barrier.

alveolodental m.  periodontal ligament.

anal m.  the dorsal part of the cloacal membrane after its division by the urorectal septum.

animal m.  a thin membranous diaphragm, as of bladder, used in dialysis or diffusion.

antral m.  a congenital abnormal membrane in the pyloric antrum, partially or completely blocking the gastric outlet. See also prepyloric atresia. Called also antral and antral web.

apical m.  the layer of plasma membrane on the apical side (the side towards the lumen) of the epithelial cells in a body tube or cavity, separated from the basolateral membrane by the zonula occludens.

aponeurotic m.  aponeurosis.

arachnoid m.  arachnoidea.

Ascherson's m.  the covering of casein enclosing the milk globules.

asphyxial m.  hyaline m. (def. 2); so called because of its interference with gaseous exchange in the lungs.

atlanto-occipital m., anterior  membrana atlantooccipitalis anterior.

atlanto-occipital m., posterior  membrana atlantooccipitalis posterior.

basal m. of semicircular duct  membrana basalis ductus semicircularis.

basement m.  a sheet of amorphous extracellular material upon which the basal surfaces of epithelial cells rest; other cells associated with basement membranes are muscle cells, Schwann cells, fat cells, and capillaries. The membrane is interposed between the cellular elements and the underlying connective tissue. It comprises two layers, the basal lamina and the reticular lamina, and is composed of Type IV collagen (which is unique to basement membranes), laminin, fibronectin, and heparan sulfate proteoglycans.

Click here to view image ■Basement membrane, comprising the basal lamina and reticular lamina, in a diagram of a section through epithelial tissue.

basilar m. of cochlear duct  lamina basilaris ductus cochlearis.

basolateral m.  the layer of plasma membrane of epithelial cells that is adjacent to the basement membrane and separated from the apical membrane by the zonula occludens.

Bichat's m.  fenestrated m.

birth m.’s  the amnion and chorion.

Bowman's m.  lamina limitans anterior corneae.

Bruch's m.  lamina basalis choroideae.

Brunn's m.  the epithelium of the olfactory region of the nose.

bucconasal m.  oronasal m.

buccopharyngeal m.  oropharyngeal m.

capsular m.  1. capsula articularis.  2. the portion of the tunica vasculosa lentis that lies posterior to the lens.

capsulopupillary m.  the part of the tunica vasculosa lentis that is around the edges of the lens.

cell m.  plasma m.

chorioallantoic m.  chorioallantois.

chromatic m.  a continuous layer of chromatin substance situated on the internal surface of a nuclear membrane.

cloacal m.  the thin, temporary barrier between the hindgut and the exterior, formed by the endoderm of the hindgut and the ectoderm of the cloaca of the embryo; its dorsal part forms the anal membrane.

complex m.  a membrane made up of several layers differing in structure.

compound m.  a membrane consisting of two distinct layers, such as the tympanic membrane.

Corti's m.  membrana tectoria ductus cochlearis.

costocoracoid m.  fascia clavipectoralis.

cribriform m.  fascia cribrosa.

cricothyroid m. ,  cricovocal m.  conus elasticus.

croupous m.  false m.

cyclitic m.  a false membrane which sometimes covers the vitreous body in cyclitis.

cytoplasmic m.  plasma m.

Debove's m.  the delicate layer between the epithelium and the tunica propria of the bronchial, tracheal, and intestinal mucous membranes.

decidual m.’s ,  deciduous m.s  membranae deciduae.

dentinoenamel m.  a continuous thin membrane laid down by ameloblasts adjoining the basement membrane separating them from the dentin in an early developing tooth.

Descemet's m.  lamina limitans posterior corneae.

diphtheritic m.  a false membrane characteristic of diphtheria and resulting from coagulation necrosis.

drum m.  membrana tympanica.

egg m.  any of several investments surrounding the oocyte: if derived from the oocyte itself, as the vitelline membrane, it is called primary; if from the follicular cells, as the zona pellucida, it is called secondary; if from the oviduct, as the albumen around rabbit's egg or the albumen and shell of hen's egg, it is called tertiary. Called also egg envelope and, collectively, lemma.

elastic m.  1. a membrane composed largely of elastic fibers.  2. see external elastic m. and internal elastic m.

elastic m., external  a fenestrated elastic membrane that constitutes the innermost component of the tunica adventitia of arteries. Called also external elastic lamina.

elastic m., internal  a fenestrated elastic membrane that constitutes the outermost component of the tunica intima of arteries. Called also internal elastic lamina.

enamel m.  1. cuticula dentis.  2. the inner layer of cells within the enamel organ of the dental germ in the fetus; called also Hannover's intermediate m.

endoneural m.  neurilemma.

endoral m.  paroral m.

epiretinal m.  a pathologic membrane partially covering the surface of the retina, probably originating chiefly from the retinal pigment epithelial and glial cells; membranes peripheral to the macula are generally asymptomatic, while those involving the macula or adjacent to it may cause reduction in vision, visual distortion, and diplopia.

excitable m.  the membrane of an excitable cell.

exocoelomic m.  Heuser's m.

extraembryonic m.’s  the trophoblastic parts of the conceptus that provide for the support of the embryo or fetus by attachment, mechanical protection, endocrine action, and the mediation of chemical exchange with the maternal circulation. They include the yolk sac, allantois, amnion, umbilical cord, and chorion, including the placenta. Called also fetal m's.

false m.  a layer resembling an organized and living membrane, but made up of coagulated fibrin with bacteria and leukocytes, such as may be formed on mucous membranes in diphtheria or in the gut with Clostridium difficile infection. Called also neomembrane and pseudomembrane.

fenestrated m.  1. a membrane that has tiny pores or fenestrae.  2. either of the elastic membranes of arteries; see internal elastic m. and external elastic m.

fertilization m.  a strong membrane formed around the fertilized ovum in some species of animals by adhesion of part of the contents of the cortical granules to the inner surface of the vitelline membrane; it prevents the entry of additional spermatozoa.

fetal m.’s  extraembryonic m's.

fibroelastic m. of larynx  membrana fibroelastica laryngis.

fibrous m. of articular capsule  membrana fibrosa capsulae articularis.

germinal m.  blastoderm.

glassy m.  1. the basement membrane of a vesicular ovarian follicle which in cross-section appears as a distinct brilliant line and which persists in the ovary long after its follicle has degenerated. Called also m. of Slavianski.  2. lamina basalis choroideae.  3. hyaline m. (def. 1).

glomerular m. ,  glomerular basement m.  (GBM) ,  glomerular capillary m.  the fenestrated basement membrane of the visceral layer of the glomerular capsule, lying adjacent to glomerular capillaries and consisting of the lamina rara interna, lamina densa, and lamina rara externa. On its outer surface is the layer of podocytes and slit pores. See also filtration barrier, under barrier.

gradocol m.’s  thin membranes made of collodion or similar substances and graded as to porosity; used in ultrafiltration and sometimes to estimate the diameters of viruses or other small particles.

ground m.  inophragma.

Haller's m.  lamina vasculosa choroideae.

Hannover's intermediate m.  enamel m. (def. 2).

hemodialyzer m.  the semipermeable membrane that filters the blood in a hemodialyzer, commonly made of cuprophane, cellulose acetate, polyacrylonitrile, polymethyl methacrylate, or polysulfone.

Henle's m.  posterior border lamella of Fuchs; see under lamella.

Henle's elastic m.  external elastic m.

Henle's fenestrated m.  fenestrated m.

Heuser's m.  a delicate sac of mesoblastic tissue that develops as a lining of the blastocyst or chorionic cavity just after implantation, forms the exocoelomic cavity, and quickly disappears; called also exocoelomic m.

high efficiency m.  a hemodialyzer membrane that has clearance characteristics that increase progressively with increases in dialysis blood flow rates; this usually implies that the membrane is not a high flux membrane.

high flux m.  a hemodialyzer membrane that has a high permeability to fluids and solutes and thus a high rate of clearance of fluids and solutes composed of large molecules.

Huxley's m.  see under layer.

hyaline m.  1. the membrane between the outer root sheath and the inner fibrous layer of a hair follicle.  2. a layer of eosinophilic hyaline material lining the alveoli, alveolar ducts, and bronchioles, found at autopsy in infants who have died of respiratory distress syndrome of the newborn (see under syndrome). Similar changes may be seen in adults who have died of viral respiratory infections. Called also asphyxial m. and vernix m.

hyaloid m.  membrana vitrea.

hymenal m.  hymen.

hyoglossal m.  a fibrous lamina connecting the under surface of the tongue with the hyoid bone.

hyothyroid m.  membrana thyrohyoidea.

intercostal m., external  membrana intercostalis externa.

intercostal m., internal  membrana intercostalis interna.

interosseous m., radioulnar  membrana interossea antebrachii.

interosseous m. of leg  membrana interossea cruris.

interspinal m.’s  see ligamenta interspinalia.

intersutural m.  the pericranium lying between the cranial sutures.

ion-selective m.  a membrane that is more permeable to particular types of ions than to other types, e.g., K⁺-selective glass membrane. Many biological membranes exhibit ion-selective behavior.

Jackson's m.  a delicate curtain or web of adhesions (regarded by some as a sheet of peritoneum) which may extend from the lateral abdominal wall to the cecum, covering the cecum and producing obstruction of the bowel; called also Jackson's veil.

Jacob's m.  layer of rods and cones.

keratogenous m.  matrix unguis.

Kölliker's m.  membrana reticularis organi spiralis.

Krause's m.  Z band.

ligamentous m.  membrana tectoria.

limiting m.  one that constitutes the border of some tissue or structure.

limiting m., external  1. a thin fenestrated layer of the pars nervosa retinae adjacent to the outer nuclear layer and through which extend the visual rods and cones.  2. a membrane investing the external surface of the embryonic neural tube. Called also outer limiting m.

limiting m., inner ,  limiting m., internal  1. internal limiting layer.  2. a membrane lining the internal surface of the embryonic neural tube.

limiting m., outer  external limiting m.

Mauthner's m.  axolemma.

medullary m.  endosteum.

mucocutaneous m.  a membrane that is partly mucous and partly cutaneous, such as the tympanic membrane.

mucous m.  tunica mucosa.

mucous m., proper  lamina propria mucosae.

mucous m. of esophagus  tunica mucosa oesophagi.

mucous m. of female urethra  tunica mucosa urethrae femininae.

mucous m. of gallbladder  tunica mucosa vesicae biliaris.

mucous m. of large intestine  tunica mucosa intestini crassi.

mucous m. of male urethra  tunica mucosa urethrae masculinae.

mucous m. of mouth  tunica mucosa oris.

mucous m. of pharynx  tunica mucosa pharyngis.

mucous m. of rectum  tunica mucosa recti.

mucous m. of small intestine  tunica mucosa intestini tenuis.

mucous m. of stomach  tunica mucosa gastris.

mucous m. of tongue  tunica mucosa linguae.

mucous m. of ureter  tunica mucosa ureteris.

mucous m. of urinary bladder  tunica mucosa vesicae urinariae.

mucous m. of vagina  tunica mucosa vaginae.

Nasmyth's m.  primary (enamel) cuticle.

nictitating m.  a transparent fold of skin lying deep to the other eyelids at the mesial side, which may be drawn over the front of the eyeball; found in reptiles and birds generally and in many mammals. See also haw. Called also third eyelid and membrana nictitans.

nuclear m.  1. either of the membranes, inner and outer, comprising the nuclear envelope.  2. nuclear envelope.

oblique m. of forearm  chorda obliqua membranae interosseae antebrachii.

obturator m.  membrana obturatoria.

obturator m. of atlas, anterior  membrana atlantooccipitalis anterior.

obturator m. of atlas, posterior  membrana atlantooccipitalis posterior.

occipitoaxial m., long  membrana tectoria.

olfactory m.  the olfactory portion of the mucous membrane lining the nasal fossa.

oral m.  oropharyngeal m.

oronasal m.  a thin epithelial plate separating the nasal pits from the oral cavity of the embryo. Called also bucconasal m.

oropharyngeal m.  a transient embryonic septum at the cranial limit of the foregut, in the depths of the stomodeum; called also buccopharyngeal m.

otolithic m.  membrana statoconiorum macularum.

ovular m.  vitelline m.

palatine m.  the membrane covering the roof of the mouth.

pansporoblastic m.  a surface membrane surrounding the sporoblasts in a pansporoblast; characteristic of microsporidian protozoa of the suborder Pansporoblastina.

paroral m.  in certain ciliate protozoa, a movable membrane-like sheet(s) formed by fusion of the bases of a longitudinal row of cilia that borders the right side of the buccal cavity; it serves to gather food and push it toward the cytostome. Called also endoral m. and undulating m. Cf. membranelle.

pericolic m.  occasional bands of peritoneum extending between the abdominal wall and the serosa of the colon.

peridental m.  periodontal ligament.

perineal m.  membrana perinei.

periodontal m.  see under ligament.

periorbital m.  periorbita.

peritrophic m.  a delicate, cylindrical sheath of chitin continuously secreted from the posterior edge of the foregut of insects and millipedes that ingest solid food, which surrounds the food as it passes through the midgut.

pharyngeal m.  fascia pharyngobasilaris.

pituitary m. of nose  tunica mucosa nasi.

placental m.  the semipermeable membrane that separates the fetal from the maternal blood in the placenta. In the human (hemochorial) placenta, it is composed of fetal vascular endothelium, connective tissue, trophoblast, and syncytium, and it becomes thinner as pregnancy progresses. Sometimes inappropriately called the placental barrier; there are only a few substances that cannot pass through the membrane.

Click here to view image ■Placental membrane separating the blood in the fetal capillaries from the maternal blood in the intervillous space. (A), chorionic villus containing the fetal vessels and surrounded by maternal blood in the intervillous space; (B), cross-section through a villus, showing the layers of the placental membrane separating the fetal blood from the maternal blood surrounding the villus.

plasma m.  the structure enveloping a cell, enclosing the cytoplasm, and forming a selective permeability barrier; it consists of lipids, proteins, and some carbohydrates, the lipids thought to form a bilayer in which integral proteins are embedded to varying degrees. Called also cell m., cytoplasmic m., and plasmalemma.

platelet demarcation m.  a more or less tridimensional system of paired membranes that serve to partition the megakaryocyte cytoplasm, each partition containing azurophilic granules and representing a future blood platelet.

pleuropericardial m.  a membrane in the embryo separating the pericardial cavity from the pleural cavity.

pleuroperitoneal m.  a membrane in the embryo separating the pleural cavity from the peritoneal cavity and developing into the posterolateral part of the diaphragm.

postsynaptic m.  the area of plasma membrane of a postsynaptic cell, either a muscle fiber or a neuron, that is within the synapse and has areas especially adapted for receiving neurotransmitters.

presynaptic m.  the area of plasma membrane of a presynaptic axon that is within the synapse and has sites (active zones) especially adapted for the release of neurotransmitters.

proper m. of semicircular duct  membrana propria ductus semicircularis.

prophylactic m.  pyophylactic m.

pseudoserous m.  a membrane resembling serous membrane, but differing from it in structure.

pupillary m.  membrana pupillaris.

pupillary m., persistent  a congenital defect in dogs in which remnants of the tunica vasculosa lentis are found on the surface of the iris or cornea, sometimes with a corneal opacity.

pyloric m.  a congenital abnormal membrane in the pylorus, partially or completely blocking the gastric outlet. See also prepyloric atresia. Called also pyloric diaphragm and pyloric web.

pyogenic m.  a membrane which produces pus.

pyophylactic m.  a fibrinous membrane lining a pus cavity and tending to prevent reabsorption of injurious materials.

quadrangular m.  membrana quadrangularis.

Reissner's m.  paries vestibularis ductus cochlearis.

reticular m.  membrana reticularis organi spiralis.

Rivinus' m.  pars flaccida membranae tympanicae.

m. of round window  membrana tympanica secundaria.

Ruysch's m. ,  ruyschian m.  the capillary layer of the choroid in addition to the pigmented layer of the retina and Bruch's membrane (the basal complex of the choroid). Called also membrana ruyschiana, tunica ruyschiana, and Ruysch's tunic.

Scarpa's m.  membrana tympanica secundaria.

schneiderian m.  tunica mucosa nasi.

Schwann's m.  neurilemma.

semipermeable m.  a membrane that is freely traversed by solvent, such as water, but which permits the passage of only certain solutes.

serous m.  tunica serosa.

shell m.  a double fibrous layer lining the shell of the egg of some animals, such as birds.

Shrapnell's m.  pars flaccida membranae tympanicae.

m. of Slavianski  glassy m. (def. 1).

slit m.  one of the exceedingly thin membranes that bridge the slit pores between adjacent pedicels of the podocytes of the renal glomerulus and close the pores at their bases.

spiral m. of cochlear duct  paries tympanicus ductus cochlearis.

stapedial m.  membrana stapedialis.

statoconic m. of maculae  membrana statoconiorum macularum.

sternal m.  membrana sterni.

striated m.  see zona pellucida (def. 1).

subepithelial m.  basement m.

submucous m.  tela submucosa.

submucous m. of stomach  tela submucosa gastris.

suprapleural m.  membrana suprapleuralis.

synaptic m.  the part of the plasma membrane of a neuron that is within a synapse; see postsynaptic m. and presynaptic m.

synovial m.  membrana synovialis capsulae articularis.

synovial m. of articular capsule  membrana synovialis capsulae articularis.

synovial m. of temporomandibular joint, inferior  membrana synovialis inferior articulationis temporomandibularis.

synovial m. of temporomandibular joint, superior  membrana synovialis superior articulationis temporomandibularis.

tarsal m.  orbital septum.

tectorial m.  membrana tectoria.

tectorial m. of cochlear duct  membrana tectoria ductus cochlearis.

tendinous m.  aponeurosis.

Tenon's m.  vagina bulbi.

thyrohyoid m.  membrana thyrohyoidea.

Toldt's m.  the part of the renal fascia anterior to the kidney.

tympanic m.  membrana tympanica.

tympanic m., secondary  membrana tympanica secundaria.

undulating m.  1. in certain flagellate protozoa, a delicate finlike cytoplasmic membrane along the lateral aspect of the body; its outer margin is formed by a flagellum that may continue free beyond the end of the body. It serves a locomotor function; when it vibrates it produces undulating movements.  2. paroral m.

unit m.  the trilaminar structure of the plasma membrane as seen under the electron microscope and postulated to be the same for the membranes of all cells, the cell nucleus, and organelles (mitochondria, etc.).

vascular m. of viscera  tela submucosa.

vernix m.  hyaline m. (def. 2); so called because it was originally thought to be the result of aspiration of vernix by the fetus in utero.

vestibular m. of cochlear duct  paries vestibularis ductus cochlearis.

virginal m.  hymen.

vitelline m.  the cytoplasmic, noncellular membrane surrounding an ovum.

vitreous m.  1. membrana vitrea.  2. lamina basalis choroideae.  3. lamina limitans posterior corneae.  4. hyaline m. (def. 1).

Volkmann's m.  a thin, yellowish membrane, studded with miliary tubercles, lining the fibrous wall of a tubercular abscess.

Wachendorf's m.  1. membrana pupillaris.  2. plasma m.

yolk m.  vitelline m.

Zinn's m.  zonula ciliaris.