Development of high-performance flexible surgical instruments is important to simplify and enable new minimally invasive procedures. New actuation technologies are necessary produce instrumentation that capable accessing difficult-to-reach anatomy performing laborious tasks without damaging delicate tissues. Recently, concentric McKibben muscles dual-chamber pneumatic artificial (PAMs) have bee...

The extremities of the human body contain several bi-articular muscles. The actions produced by muscles at the joints they cross are greatly influenced by joint moment arms and muscle length. These factors are dynamic and subject to change as joint angles are altered. Therefore, to more completely understand the actions of such muscles, the angles of both joints must be manipulated. This report...

Recent studies suggest that the number of nerve terminals maintained per motoneuron and perhaps other motoneuron properties (Grinnell and Herrera, 1980a; Grinnell and Trussell, 1983) influence transmitter release. We have examined, in detail, the structure and function of motoneurons innervating two different twitch muscles, the sartorius and the ext. long. dig. IV (e.l.d.) in the adult frog us...

By manipulating trunk angle in ergometer cycling, we studied the effect of body configuration on muscle recruitment and joint kinematics. Changing trunk angle affects the length of muscles that span the hip joint. It is hypothesized that this affects the recruitment of the muscles directly involved, and as a consequence of affected joint torque distributions, also influences the recruitment of ...

When the resistance to a forceful isometric bite is suddenly removed in unloading experiments, the bite force drops to zero and the mandible reaches a constant velocity. This occurs at an initial bite force of 100 N after approximately 12 ms when the incisors have moved 4.5 mm. Reflex activity is far too slow to limit the velocity at impact. To explore the influence of other factors (cocontract...

1. The mesothoracic wings of tettigoniid insects are used in song production and flight; the metathoracic wings in flight only. In Neoconocephalus triops the wing stroke frequency during flight is about 25 Hz; the frequency during singing about 100 Hz. 2. The twitch duration of mesothoracic, first tergocoxal (Tcxl) wing muscles is only about one-half the duration of the upstroke or downstroke p...

Sarcomere length was measured in flexor carpi ulnaris (FCU) muscles from patients with severely spastic wrist flexion contractures (n = 6), as well as from patients with radial nerve injury and a normally innervated FCU (n = 12). Spastic FCU muscles had extremely long sarcomere lengths with the wrist fully flexed (3.48 +/- 0.44 microm) compared to the FCU muscles of patients with radial nerve i...

The interaction between fascicle and tendinous tissues (TT) in short-contact drop jumps (DJ) with three different drop heights [low (Low), optimal (OP), and high (High)] was examined with 11 subjects. The ground reaction force (F(z)) and ankle and knee joint angles were measured together with real-time ultrasonography (fascicle length) and electromyographic activities of the medial gastrocnemiu...

Skeletal muscles change length and develop force both passively and actively. Gearing allows muscle fiber length changes to be uncoupled from those of the whole muscle-tendon unit. During active contractions this process allows muscles to operate at mechanically favorable conditions for power or economical force production. Here we ask whether gearing is constant in passive muscle; determining ...

WEISFELDT, MYRON L., W. A. LOEVEN, AND N. W. SHOCK. Resting and active mechanical properties of trabeculae carneae from aged male rats. Am. J. Physiol. 220(6): 1921-1927. 1971.-Trabeculae carneae from the left ventricles of 1 lto 13and 26to 3 l-monthold male rats were examined in terms of the active and resting length-tension curves. No significant difference between the two groups was noted fo...