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Biomedical subjects

B Salén

Publications and source records attributed to B Salén.

At least 19 recordsLinked to original sources
PubMed1985

The vascular supply of the rat tympanic membrane.

The vascular supply of the rat tympanic membrane (TM) was studied by means of otomicroscopy, angiography, acrylic casts, and light microscopy. The branches of the external carotid artery in the external auditory meatus were found to vascularize 1) the pars flaccida, 2) the manubrial part of the pars tensa, and 3) the junction between the fibrocartilaginous ring of the TM and the tympanic sulcus of the temporal bone. The TM vessels of areas 1 and 2 were found beneath the squamous epithelium, close to mast cells and nerve bundles. Vessels originating from the tympanic cavity (also probably emanating from the external carotid artery) supplied the periphery of the pars tensa with minute branches, localized immediately beneath the tympanal epithelium. The portion of the pars tensa between the manubrial part and the periphery lacked a vascular system. Upon mechanical stimulation (gentle pressure on the handle of the malleus), the normally visible vessels dilated and minute branches appeared. This dilation may be caused, at least partly, by a release of vasoactive substances from mast cells and/or nerves in its vicinity. Even under mechanical stimulation, a large portion of the pars tensa seemed to be devoid of vessels. The nutrition of this part may be served by diffusion, with nutrients originating from the vessels in the tympanal rim and along the handle of the malleus. The architecture of the attachment of the fibrocartilaginous ring to the bony sulcus of the temporal bone is quite unique. Thus, the flow in the dense vascular network between these structures may be affected by an altered tension in the pars tensa.

Angiography↗
PubMed1985

Pharmacological characterization of receptors on blood vessels in the tympanic membrane involved in otitis media.

Acetylcholine dropped onto the meatal surface of the tympanic membrane evoked vasodilatation and a vascular leakage to the middle ear cavity. The vasoreactions were atropine-resistant. Substance P and vasoactive intestinal polypeptide (VIP) injected intravenously caused a marked vascular leakage and VIP also vasodilatation. These blood vessel changes seem to be regulated by the parasympathetic nerves as they were inhibited by vagotomy. Constriction of the tympanic membrane vessels was mediated through alpha-receptors.

Animals↗
PubMed1983

The anatomy of the eustachian tube in the rat: a macro- and microscopical study.

The rat eustachian tube (ET), from the nasopharyngeal orifice to the tympanal orifice, is about 4.5 mm long, of which the naso-medial membranous part (the nasopharyngeal orifice) measures about 1.5 mm and the occipito-lateral bony portion about 3 mm. The nasopharyngeal orifice is surrounded by two soft, lip-like, mucosal swellings--one ventral and one cranial--both easily mobile. The muscles related to the tubal opening mechanisms are the salpingopharyngeus, the tensor veli palatini and the levator veli palatini muscles. The salpingopharyngeus muscle originates partly from the cranial lip, whereas the palatal muscles originate partly from the ventral lip. The tympanal two thirds of the mucosal lining of the ET is cranially guided by a cartilage and incompletely framed by bony structures. The tympanal orifice is situated in the nasal part of the medial wall, well above the floor of the bulla. The tensor tympani muscle does not seem to take part in the opening and closing mechanisms of the ET. The mucosal lining of the ET consists of a respiratory epithelium with numerous glands in the lamina propria. It is suggested that the tubal muscles control the passage through the ET by moving the lip-like folds of the nasopharyngeal orifice. The anatomy of the rat ET is comparable to that described in Homo and it can be concluded that the rat ET might be a good model for studying the function of the human ET.

Animals↗
PubMed1983

Appearance of effusion material in the attic space correlated to an impaired Eustachian tube function.

In adult Sprague-Dawley rats a dysfunction or a total blockade of the Eustachian tube was established by various experimental procedures. The appearance of effusion material in the attic was subsequently considered to be evidence of incomplete ventilation of the middle ear cavity. Though the salpingopharyngeus muscle (SPM) seemed to be the muscle which could open the Eustachian tube maximally, splitting of the soft palate and consequent interference with the tensor veli palatini muscle (TVPM) and the levator veli palatini muscle (LVPM)--but obviously not with the salpingopharyngeus muscle (SPM)--caused the effusion material to be produced in the middle ear cavity. Neither blockade by about 80% of the tympanal orifice nor severing of the tendon of the tensor tympani muscle (TTM) close to the malleus produced any signs of effusion material whatsoever. Our findings strongly suggest that the most important part of the Eustachian tube, as regards ventilation, is the nasopharyngeal portion, as a normally functioning TVPM and LVPM seems to be an absolute prerequisite to prevent effusion material from developing in the attic.

Animals↗
PubMed1983

The stapedial artery in the rat. A microscopical study under normal conditions and in otitis media with effusion.

Arteria stapedialis in the rat was studied in healthy rats and in experimental otitis media with effusion (OME). The mean diameters of the vessel was calculated to approximately 460 microns (healthy) and 430 microns (otitic) (no significant difference). The tunica intima consisted of an endothelium and a well-developed elastica interna. The tunica media was composed of 2-3 layers of smooth muscle cells. The adventitia was thicker than the media and consisted of bundles of collagen fibers. The artery in the middle ear cavity was quite naked covered only with the middle ear mucosa. The stapedial artery did not appear to be involved in the production of effusion in experimentally induced OME.

Animals↗
PubMed1982

Structure of the pars flaccida after occlusion of the Eustachian tube or blockade of the tympanic isthmus.

In this experimental study performed on the rat middle ear either the Eustachian tube or the tympanic isthmus was blocked via the tympanic bulla with a polyethylene plug or a piece of Gelfoam, respectively. Effusion material was immediately observed in the attic space and subsequently the pars flaccida was drawn in a medial direction to form a retraction pocket. The initial changes in the pars flaccida structure were a degranulation of the mast cells and concomitantly metaplasia of the mucosal epithelium into cells displaying numerous osmiophilic inclusions, vacuoles and multivesicular bodies. It cannot be excluded that the initial cause of the effusion production is the histamine released from mast cell granules.

Animals↗
PubMed1980

Calculation of noise dose from time distribution of sound levels.

The noise from ten different sites in a machine factory was measured and cumulative time distributions of the sound pressure were constructed. From these distributions it is possible to calculate the energy mean level, the equivalent sound level as well as the average sound pressure level. Calculations based on knowledge of the times during which only a few sound pressure levels are exceeded give values deviating systematically from the exact value. Because of the systematic nature of the deviations corrections can be made for them. The accuracy of this method is relatively high.

Acoustics↗
PubMed1979

The role of the pars flaccida in the mechanics of the middle ear.

The role played by the pars flaccida in the functioning of the middle ear is not altogether clear. The aim of our research was to study the movements of pars flaccida in altering the air volume in the middle ear. By using a sond placed either in the tympanic bulla or in the Eustachian tube in the rat, the middle ear can be insufflated or aspirated with exact volumes of air. Pars flaccida reacted promptly to the changes, while pars tensa remained immobile. A large air volume caused perforation of the pars flaccida. It seems that pars flaccida's function may consist in maintaining a constant middle ear pressure within certain limits, by changing its position.

Animals↗
PubMedDate not supplied

Mechanisms in middle ear effusion production caused by irritation of the external auditory canal.

In an animal model, a stream of chilled air blown into the external auditory canal evoked an edematous pars flaccida and accumulation of a serous effusion in the attic. The degree of inflammatory changes depended on the temperature of the stimuli. The nervous system appears to mediate the observed changes, as the vagus nerve, representing the parasympathetic system, potentiates vascular leakage, and the sympathetic nerves inhibit leakage.

Animals↗
PubMedDate not supplied

Electromyogram of the tensor tympani muscle in man during swallowing.

Experiments were carried out on 2 patients who underwent an operation for chronic otitis media, whereupon the tensor tympani muscle was visualized. A unipolar platinum electrode was inserted into the muscle belly. EMG recordings were made during swallowing and other motor activity. Distinct, pronounced EMG activity was recorded from both patients every time they swallowed. It was concluded that the tensor tympani muscle participates in the act of swallowing and thereby probably contributes to the ventilation of the middle ear.

Deglutition↗
PubMedDate not supplied

The healing pattern of experimental pars flaccida perforations.

The aim of this investigation was to ascertain how a traumatic perforation of the pars flaccida heals and whether this could explain the way in which the retraction pocket develops. In rats, traumatic pars flaccida perforations were performed on both ears and the healing pattern was registered after various intervals. The perforations healed in 7-10 days, forming in the first instance an indrawing of the pars flaccida and after 12-14 days an adhesive retraction, i.e., ther pars flaccida adhered to the neck of malleus. The retraction pocket was filled with wax, keratin and detritus. At the base of the retraction, epithelial inclusions could be found, which could explain why these retractions were not self-cleaning.

Animals↗