Suspensory Apparatus Research Articles

Clinical and pathological observations concerning the aetiology of primary lens luxation in the dog.

A series of 123 consecutive referred cases of lens dislocation in the dog were classified as primary (100), secondary (21) and congenital (two). Cases designated as primary lens luxation comprised only the terrier breeds or crossbreds and collectively appeared to represent a single clinical entity characterised by age of onset (mean four to five years), essential bilaterality and the apparent absence of antecedent ocular disease. Elevated intraocular pressures were encountered in many eyes exhibiting subluxation. However, in three Tibetan terriers, on which tonometry was performed on a daily basis for approximately one year during the period of subluxation and before the development of luxation, there was no evidence of abnormal intraocular pressure change, suggesting that ocular hypertension in primary lens luxation is a secondary and not a primary development. All but one of nine affected eyes representing three terrier breeds showed abnormalities of the suspensory apparatus of the lens (zonule) which resembled those reported previously in Tibetan terriers bred for the condition.

Model of the accommodative mechanism in the human eye

The crystalline lens of the age 11 human eye has been modelled mathematically, using simplified assumptions about lens curvature, internal organization and elasticity. From this representation, expressions for description of strain and stress during accommodation have been obtained. Solution of these equations indicates that the lens capsule acts as a force distributor, spreading tension applied by the suspensory apparatus evenly over the surface of the underlying lens material. It also becomes clear that the vitreous body provides an essential support function during the accommodative process. Finally, the relative contribution of lens-associated structures has been determined for five different values of the Poisson ratio. In order for accommodation to occur by relaxation of zonular tension, this value must be greater than 0.38; with an additional constraint of the net axial force equalling zero during a small accommodative change, the Poisson ratio equals 0.46.

Diseases of the Suspensory Apparatus

Diseases of the Suspensory Apparatus

Modulatory multiplicity in the feeding mechanism in cichlid fishes, as exemplified by the invertebrate pickers of Lake Tanganyika

Electromyography, motion analysis, osteology, myology and feeding behaviour of a morphologically specialized monophyletic lineage of cichlids in Lake Tanganyika have revealed that Eretmodus, Spathodus and Tanganicodus possess a feeding apparatus with a more extensive functional repertoire than that of any other teleost studied to date. When collecting a wide range of foods by inertial suction this trophic group can employ two strategies, a preprogrammed cyclical, energy saving pattern, or a modulated mode effected by extensive overlap of the firing patterns of multiple muscles resulting in a precise control of the magnitude and direction of suction. When dislodging sessile prey from the substrate the complexity of electromyographic and kinematic patterns increases. Because upper jaw protrusion can be effected and controlled independently from the complex couplings causing mouth opening and movements of the suspensory apparatus, a new decoupled model of upper jaw protrusion is proposed. The decoupled model predicts that upper jaw protrusion can be effected directly by contraction of epaxial muscles that raise the neurocranium, causing the premaxillae to slide anteroventrally. Upper jaw protrusion can be modulated continuously and directly by balanced cocontractions of antagonistic muscle sets giving the decoupled model an improved function over a very extensive range. The morphologically symmetrical muscular apparatus can function asymmetrically. Very pronounced asymmetrical firings of multiple muscles produce a continuously modulated jaw mechanism with an extensive repertoire.

Three-dimensional architecture of the suspensory apparatus of the lens of the Rhesus monkey

the three-dimensional ultrastructure of the lens suspensory apparatus and its supporting tissues were determined in the adult Rhesus monkey eye, Single zonular bundles (4–6 μm) composed of parallel oriented fibrils were traced from the lens surfaces to the ciliary body. There are four major tracts of zonular fibrils; the anterior lens to pars plana, the equatorial region to ciliary process, the posterior lens to pars plana, and the posterior lens to ciliary process to pars plana. The course and insertion patterns of the anterior and posterior zonules suggest separate functions. The anterior zonules are arranged in a pattern suited for anterior face contour changes required in accommodation. The posterior zonular pattern is better arranged for maintenance of lens position. The anterior hyaloid membrane is seen as a mesh-work of fibrils with attachments around the ora serrata and on the lens posterior. It also serves as a lens support structure. In contrast, the adjacent vitreous is composed of fibrils plus globular units which are probably hyaluronic acid. The construction of the ciliary processes, the inserting posterior zonules, and the circumferential fibrils between the ciliary processes form a complex capable of reversible response to ciliary muscle contraction. In the light of these findings, a reconsideration of the prineipal theories of accommodation is in order.

The suspensory apparatus of the female bladder neck.

Lateral cystourethrograms have shown a forwards-downwards displacement of the bladder neck in bladder base insufficiency, a type of stress incontinence. In search for the structure which in normal subjects prevents this displacement, a series of 10 dissections of the female pelvic floor was undertaken. The formerly described structures: The pubo-vesical ligaments and the precervical arc are shown. As a new finding it is demonstrated how these structures are dependent on an upwards-backwards suspension by a strong ligament in the fascia over the levator muscle.

Comparative and functional studies on the suspensory apparatus of the lens (Mammalia)

The suspensory apparatus of the lens has been studied in two species of placental mammals (dog and horse) and in two species of marsupials (phalanger and wallaby). Particular attention has been paid to the suspensory apparatus of the dog and the phalanger. It has been found that the suspensory apparatus of the lens shows great morphological variability, although some features generally are more common in one species than in the others. For instance, in the dog there is a tendency to form fibrous bundles, an uneven distribution of fibres around the lens, and a fan-like arrangement of these fibres at their attachment to the lens. In the phalanger the fibres are evenly distributed around most of the circumference of the lens and the bundles, if formed, are slender. An area devoid of fibres, described as a diastema,is also present.

One-Stage Perineal Surgery for Complete Rectal Prolapse

Because of the frequent occurrence of coexisting pathology, the patient undergoing surgical repair of complete rectal prolapse may require relatively long preoperative hospitalization. The one-stage approach illustrated and described here is advocated because of the facility it offers in plastic reconstruction of the rectal suspensory apparatus and because it minimizes complications and recurrences.

Mechanical input impedance of human teeth in vivo.

The mechanical input impedance of teethin vivo has been measured over the frequency range of 60–5000 c/s. A generator was used which delivered a sinusoidal force of variable frequency and constant peak-to-peak amplitude of 4·4×104 dyn. Our data plus those of others indicate that the suspensory apparatus of the tooth consists of several equivalent springs and dampers. The purpose of the initial study is to establish a correlation between some aspect of mechanical impedance and ‘clinical mobility’ or ‘looseness’ of teeth. An increase in tooth mobility has long been regarded as a cardinal finding in periodontal disease and a key consideration in determining the feasibility and mode of restoring lost dental function. Finally, we hope to develop a suitable clinical instrument for measuring tooth mobility objectively.

Functional morphology of the head of the anabantoid teleost fish Helostoma temmincki.

AbstractOsteology, myology and motion analysis of the head of the anabantoid fish Helostoma temmincki, a specialized filter feeder, has revealed six functional units: neurocranium, suspensory apparatus, opercular apparatus, hyoid apparatus, branchial apparatus and pectoral girdle. Interactions between the functional units take place through four couplings involved in opening and protruding the jaws. The first coupling is activated in the beginning of the opening cycle by the levator operculi muscle through the opercular apparatus, interoperculomandibular ligament and mandible. The second is activated during feeding by contraction of the sternohyoideus through the hyoid apparatus, interopercular, interoperculomandibular ligament and mandible. The third coupling is active during feeding and “kissing” by contraction of epaxial muscles through mediation of the neurocranium to the jaw apparatus. The fourth coupling is the only one active during air intake and involves contraction of the levator arcus palatini which abducts and rotates the suspensory apparatus forwards, causing the mandible to drop. The retention of isolated ancestral characters during mosaic evolution are explained in terms of the maintenance of couplings which represent functional associations of seemingly remote structures. When natural selection acts on one component of a functional unit or coupling, it essentially acts on all associated elements simultaneously causing character complexes to evolve in common evolutionary trends. It is feasible that functional analysis can separate primary from secondary evolutionary trends.

Volvulus of the stomach

Chronic volvulus of the stomach is of rare occurrence. Factors inducing this lesion are chiefly, visceroptosis, abnormally long mesenteric attachment, and other congenital malformations of the suspensory apparatus. The acute type of chronic volvulus needs immediate surgical interference consisting of a reduction and pexy. The chronic type is often intermittent, reversible, and at times, may be approached medically. However, if a concomitant lesion is found responsible, surgery is necessary. A case of chronic volvulus of the stomach is presented. A huge penetrating ulcer on the lesser curvature with subsequent complications necessitated surgical interference. An anterior antecolic gastroenterostomy was successfully performed.

Sémiologie oculaire, le cristallin, Anatomie. Physiologie. Pathologie.

This, the third book of this series, deals exclusively with the crystalline lens and its suspensory apparatus. The subject matter is divided into three parts, the first of which has to do with the gross and microscopic anatomy. Included is a well written and comprehensively illustrated portion on the development of the human lens with sufficient comparative embryology to be instructive. Four short pages are devoted to the examination of the lens with the Gullstrand slit lamp and binocular microscope. The second part of the book deals with the physiology of the lens, and naturally much space is devoted to a consideration of the optics of the lens. This is well written, and the ultramathematical phases have been eliminated. Of course, the author leans toward the Tscherning theory of accommodation; however, this natural inclination does not make him gloss over the other theories too sketchily. The discussion of accommodation leads

An account of the devonian fish, Palæospondylus Gunni , traquair

This fossil, which has been variously referred to an alliance with Lampreys, Tadpoles, and Lung-fish, has been successfully studied by means of serial sections. The ventral surface of the head bears four pairs of branchial bars, with the last of which two post-branchial plates, the so-called “post-occipital” plates, are associated; in front of the branchial bars are two pairs of structures, which are regarded as representing the lower jaw and hyoid; they are supported by a suspensory apparatus, which may represent the palato-quadrate and hyo-mandibular elements. The branchial arches are wholly unlike anything seen in Marsipobranchs, but call to mind the similar structures in the Dipnoi and larval Amphibians. The dorsal side of the skull shows a large cranial cavity with thin vertical walls, but no complete roof, a pair of auditory and a pair of nasal capsules.

XX. On the development of the ossicula auditus in the higher Mammalia

Since the discovery by Meckel of the cartilage which bears his name and the subse­quent discovery by Rathke of the cartilaginous rods immediately succeeding it, anatomists and embryologists have not failed to be intensely interested in the elucida­tion of their history. Huschke was the first to limit the origin of the ossicula to the cartilages of the first two post-oral arches, but it is to Reichert that the first full and masterly description of these two cartilages is due. Looking at the wide­spread existence of these two rods in all classes of the Vertebrata, and the differentia­tion taking place at their proximal extremities, which may result either in the formation of a suspensory apparatus, or in one which, changing its function, is sub­ordinated to the organ of hearing, it can scarcely be wondered at that the opinions concerning the homology of the differentiated parts should be various and conflicting. Nor can it be otherwise, seeing that as yet there is no general agreement as to what parts are or are not derived from or connected with the upper extremities of these two cartilages in any one class of the Vertebrata. This portion of my work refers only to the Mammalia, but I hope soon to complete my observations upon the remaining classes of the Vertebrata. Before passing to the description of my own work I shall give a brief summary of the various views that have been advanced respecting the origin of the ossicula auditus.

Art. XXV.– Treatment of Fractures of the Lower Extremity by the Use of the Anterior Suspensory Apparatus

Art. XXV.– Treatment of Fractures of the Lower Extremity by the Use of the Anterior Suspensory Apparatus

Art. I. ??? The Anterior Suspensory Apparatus for the Treatment of Fractures of the Lower Extremity

Art. I. ??? The Anterior Suspensory Apparatus for the Treatment of Fractures of the Lower Extremity