Neuromuscular correlates to the evolution of flapping flight in birds.

The neuromotor pattern (i.e. the onset/offset of muscle contraction within the locomotor cycle) is conserved for some homologous muscles of the tetrapod shoulder but not others in the transition from terrestrial locomotion to flight.

Neuromuscular organization of avian flight muscle: Morphology and contractile properties of motor units in the pectoralis (pars thoracicus) of pigeon (Columba livia).

We used acid digestion and glycogen depletion to determine fascicle organization, fiber morphology, and physiological and anatomical features of individual motor units of an in-series muscle, the pectoralis (pars thoracicus) of the pigeon (Columba livia). Most fascicles are attached at one end to connective tissue. Average fiber length in the four regions examined range from 42% to 66% of average fascicle length.

The contractile properties of the M. supracoracoideus In the pigeon and starling: a case for long-axis rotation of the humerus.

Wing upstroke in birds capable of powered flight is kinematically the most complicated phase of the wingbeat cycle. The M. supracoracoideus (SC), generally considered to be the primary elevator of the wing, is a muscle with a highly derived but stereotyped morphology in modern flying birds.

The functional anatomy of the shoulder in the European starling (Sturnus vulgaris).

The excursions of wing elements and the activity of eleven shoulder muscles were studied by cineradiography and electromyography in European starlings (Sturnus vulgaris) flying in a wind tunnel at speeds of 9-20 m s . At the beginning of downstroke the humerus is elevated 80-90° above horizontal, and both elbow and wrist are extended to 90° or less. During downstroke, protraction of the humerus (55°) remains constant; elbow and wrist are maximally extended (120° and 160°, respectively) as the humerus passes through a horizontal orientation.

Musculotopic innervation of the primary flight muscles, the pectoralis (Pars thoracicus) and supracoracoideus, of the pigeon (Columba livia): a WGA-HRP Study.

The distribution of motoneurons innervating the primary depressor and elevator muscles of the wing of the domestic pigeon (Columba livia) was studied by using the retrograde axonal tracer lectin-conjugated horseradish peroxidase (WGA-HRP). Injection of WGA-HRP into the pectoralis (pars thoracicus) labeled neurons in the ventromedial corner of the lateral motor column of the spinal cord. These neurons were arranged in a column extending from spinal segment X or XI to spinal segment XII or XIII.

Neuromuscular organization of the pectoralis (pars thoracicus) of the pigeon (Columba livia): implications for motor control.

The pectoralis (pars thoracicus) of the domestic pigeon (Columba livia) is divisible into two anatomical parts, the pars sternobrachialis (SB) and the pars thoracobrachialis (TB). Innervation to this complex is from rostral and caudal branches of the brachial ventral cord. In four anesthetized pigeons, the distribution of muscle units associated with each nerve branch was mapped after prolonged stimulation of each nerve and subsequent analysis for muscle fiber glycogen.

A cineradiographic analysis of bird flight: the wishbone in starlings is a spring.

High-speed x-ray movies of European starlings flying in a wind tunnel provide detailed documentation of avian skeletal movements during flapping flight. The U-shaped furcula (or "wishbone," which represents the fused clavicles) bends laterally during downstroke and recoils during upstroke; these movements may facilitate inflation and deflation of the clavicular air sac. Sternal movements are also coupled with wingbeat, ascending and retracting on downstroke and descending and protracting on upstroke in an approximately elliptical pathway.

A functional analysis of the primary upstroke and downstroke muscles in the domestic pigeon (Columba livia) during flight.

In domestic pigeons (Columba livia), the electrical activity of the major depressor muscle of the wing, the pectoralis (pars thoracicus), beings in late upstroke well before the wing begins its downstroke excursion. The two architecturally distinct heads of the pectoralis, the sternobrachialis and the thoracobrachialis, are differentially recruited during take-off, level flight and landing. In addition to wing depression, the sternobrachialis protracts the humerus and the thoracobrachialis retracts the humerus.

Structure and neural control of the pectoralis in pigeons: implications for flight mechanics.

The pectoralis muscle in pigeons (Columba livia) is composed of two heads (sternobrachialis, thoracobrachialis) that are separately innervated and have different fiber orientations. High-speed film and electromyographic studies of free-flying pigeons reveal that the pectoralis is activated prior to wing depression (the power stroke) and that its two heads are differentially recruited during takeoff, level flight, and landing. The electrical activity patterns of both heads support an interpretation that intramuscular elasticity provides energy storage.

Kinematics of locomotion in cats with partially deafferented spinal cords: the spared-root preparation.

The spinal cord was partially deafferented in two cats by dorsal rhizotomy sparing the dorsal root, L6. Kinematic methods were used to study movements of the pelvis and the affected hindlimb during treadmill walking. The E2 yield of the ankle 2 days postsurgery was of greater duration and extent than normal.

Motor units of the primary ankle extensor muscles of the opossum (Didelphis virginiana): functional properties and fiber types.

Motor units of the medial gastrocnemius (MG) and the single lateral gastrocnemius/soleus (LG/S) muscles of the opossum (Didelphis virginiana) were found to have uniformly slow contraction times relative to homologous muscles of the cat. Though a broad range of peak tetanic tensions was found among motor units from both muscles, most of the motor units were quite large relative to tension of the whole muscle. Comparison of the relative sizes of motor units showed that those of LG/S are significantly larger and slower than the units of MG.

An effective sleeving technique in nerve repair.

This report describes the use of a porous polymeric sleeve (Gore-tex) to direct nerve fiber growth after axotomy. Select nerves of the triceps surae muscles in 5 adult cats were surgically isolated, sectioned, and crossed or self- reunited . A piece of Gore-tex, 15 mm in length, was compressed to 5 mm and sleeved over each distal nerve end.

The functional anatomy of the shoulder of the savannah monitor lizard (Varanus exanthematicus).

The excursions of the scapulocoracoid and forelimb and the activity of 18 shoulder muscles were studied by simultaneous cineradiography and electromyography in Savannah Monitor lizards (Varanus exanthematicus) walking on a treadmill at speeds of 0.7-1.1 km/hour.

Histochemical and physiological properties of cat motor units after self-and cross-reinnervation.

1. This report describes selected histochemical and physiological properties of the motor units of adult cat soleus muscle approximately one year after self- and cross-reinnervation with the nerve of the heterogenous flexor hallucis longus (f.h.

Electrical activity and relative length changes of dog limb muscles as a function of speed and gait.

Electrical activity and length changes of 11 muscles of the fore- and hind- limbs of dogs walking, running, and galloping on a treadmill, were measured as a function of forward speed and gait. Our purpose was to find out whether the activity patterns of the major limb muscles were consistent with the two mechanisms proposed for storage and recovery of energy within a stride: a 'pendulum-like' mechanism during a walk, and a 'spring-like' mechanism during a run. In the stance phase of the walking dog, we found that the supraspinatus, long head of the triceps brachii, biceps brachii, vastus lateralis, and gastrocnemius underwent only minor length changes during a relatively long portion of their activity, Thus, a major part of their activity during the walk seems consistent with a role in stabilization of the joints as the dog 'pole-vaulted' over its limbs (and thereby conserved energy).

Is resistance of a muscle to fatigue controlled by its motoneurones?

The original experiment of Buller et al. and the many subsequent confirmatory reports clearly show that the time-to-peak tension and many other speed-related parameters of slow and fast muscle fibres are dictated by the motoneurone. It has been concluded that the motoneurone exerts this control of the physiological and associated biochemical properties by the frequency at which it excites the muscle fibre.

Ipsilateral limb variation in cats during overground locomotion.

The timing interval between the onset of knee extensor EMG (vastus lateralis) and the onset of the ipsilateral elbow flexor EMG (brachialis) was studied in adult cats during overground walking, trotting and galloping. Concurrent finding of the animals in locomotion was used to relate the electrical activity of the muscles to the physical events in a step cycle. The observed variability in the interval between the onset of knee extensor EMG and the onset of elbow flexor EMG lead to the conclusion that it is not appropriate to postulate a rigid neural coupling mechanism for the control and coordination of ipsilateral limbs in locomotion.