Abdominal wall muscles have a unique morphology suggesting a complex role in generating and transferring force to the spinal column. Studying passive mechanical properties of these muscles may provide insights into their ability to transfer force among structures. Biopsies from rectus abdominis (RA), external oblique (EO), internal oblique (IO), and transverse abdominis (TrA) were harvested fro...

Histochemical properties, muscle fiber cross-sectional area, muscle fiber length, and the oxidative capacity of masticatory muscles of female rhesus monkeys were assessed following alteration in functional length by an intraoral appliance or by detachment of the muscle. Experimental groups received the appliance only (A); the appliance and subsequent detachment of the masseter (AD); the applian...

In this study, we compare rotator cuff muscle architecture of typically used animal models with that of humans and quantify the scaling relationships of these muscles across mammals. The four muscles that correspond to the human rotator cuff - supraspinatus, infraspinatus, subscapularis and teres minor - of 10 commonly studied animals were excised and subjected to a series of comparative measur...

Recent studies on the canine parasternal intercostal, sternomastoid, and scalene muscles have shown that the maximal changes in airway opening pressure (delta Pao) obtained per unit muscle mass (delta Pao/m) during isolated contraction are closely related to the fractional changes in muscle length per unit volume increase of the relaxed chest wall. In the present study, we have examined the val...

PURPOSE Metacarpal fractures are common in hand surgery. Metacarpal shortening ranging from 2 mm to as much as 10 mm has been deemed acceptable in the literature. We examined the effect of metacarpal shortening on interosseous muscle architecture and predicted force production capacity based on the standard muscle length-tension curve (commonly known as the Blix curve). METHODS The dorsal int...

In the left ventriculogram in the right anterior oblique projection the plane of the mitral valve is seen in profile and the papillary muscle shadows are outlined. The distance from the middle of the papillary muscles to the plane of the mitral valve during systole was used to assess the average length of the chordae tendineae, and the area of the papillary muscle shadows was measured as an ind...

Transmembrane potentials and isometric force were recorded in right ventricular muscles from cats with right ventricular failure 3-127 days after chronic partial pulmonary artery obstruction. For the majority of failed muscles (at 36°C, 30 stimuli/ min), resting potential, action potential overshoot, action potential maximum rate of rise, isometric active force at optimal length (Po), and dP/dt...

Right ventricular papillary muscles from normal rabbits and rabbits with sustained pulmonary artery constriction (67% decrease in external diameter) were studied at several resting muscle lengths and at an early instant in the isometric twitch. Instantaneous force-velocity data were obtained at 30-38% of time to peak tension (TPT) and at 96%, 98%, and 100% of the resting muscle length at which ...

The purpose was to investigate the contribution of mechanical damage to sarcomeres to the greater susceptibility of dystrophic muscle fibers to contraction-induced injury. Single stretches provide an effective method for studying mechanical factors that contribute to the initiation of contraction-induced injury. We hypothesized that, after single stretches, the deficits in isometric force would...

The sliding filament and cross-bridge theories of muscle contraction provide discrete predictions of the tetanic force-length relationship of skeletal muscle that have been tested experimentally. The active force generated by a maximally activated single fiber (with sarcomere length control) is maximal when the filament overlap is optimized and is proportionally decreased when overlap is dimini...