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PubMed1976

Forelimb performance by squirrel monkeys (Saimiri sciureus) before and after dorsal column lesions.

Old World monkeys with dorsal column lesions have exhibited slow, inept reaching movements in extrapersonal space under neurological examination. The purpose of the present study was to obtain quantified observations of such performance in similarly prepared squirrel monkeys. Squirrel monkeys with high cervical lesions of the dorsal columns were tested preoperatively and postoperatively. They were compared with sham-operated controls on three tests requiring fast reaching for stationary bait and on one test requiring catching of a falling bait. The experimental animals were impaired relative to the controls postoperatively only on bait catching. Possible reasons for the apparent discrepancy between the forelimb performance of New World monkeys and Old World monkeys are discussed.

Animals↗
PubMed1980

Recovery of forelimb placing after lateral hypothalamic lesions in the cat: parallels and contrasts with development.

Recovery of forelimb placing after lateral hypothalamic lesions in the cat is similar in several respects to the development of placing in kittens. In both recovery and development, the sequence in which sensory systems acquire control over placing is the same: vestibular--proprioceptive--tactile--visual. In addition, within each sensory modality, placing is initially sluggish, exaggerated in amplitude, and susceptible to rapid habituation. Unlike development, however, the recovery of visually guided placing does not require visuomotor experience.

Age Factors↗
PubMed2001

Forelimb locomotor generators and quadrupedal locomotion in the neonatal rat.

The spinal localization of the forelimb locomotor generators and their interactions with other spinal segments were investigated on in vitro brainstem-spinal cord preparations of new-born rats. Superfusion of the cervicothoracic cord (C1-T4) with high K+/low Mg2+ artificial cerebrospinal fluid (aCSF) evoked rhythmic motor root activity that was limited to low cervical (C7, C8) and high thoracic (T1) spinal levels. This activity consisted of synchronous, homolateral bursts and a typical alternating bilateral pattern. Rhythmic activity with similar locomotor-like characteristics could be induced with either serotonin (5-HT, 5 microm), N-methyl-d-aspartate (NMDA, 5 microm), kainate (10 microm) or a "cocktail" of 5-HT (5 microm) and NMDA (5 microm). During 5-HT/NMDA perfusion of the cervicothoracic cord, induced bursting was no longer restricted to C7-T1 levels, but also occurred at cervical C3-C5 levels and with C5-C8 homolateral alternation. Spinal transections between C6 and C7 cervical segments did not abolish rhythmic activity in C7-T1, but suppressed locomotor-like rhythmicity at C3-C5 levels. Reduced regions comprising the C7-C8 or C8-T1 segments maintained rhythmicity. Superfusion of the whole cord with 5-HT/NMDA induced ventral root bursting with similar frequencies at all recorded segments (cervical, thoracic and lumbar). After isolation, the T3-T10 cord was unable to sustain any rhythmic activity while cervical and lumbar segmental levels continued to burst, albeit at different frequencies. We also found that the faster caudal and the slower rostral locomotor generators interact to produce coordinated locomotor-like activity in all segments of the intact spinal cord. In conclusion, C7-T1 spinal levels display a strong motor rhythmogenic ability; with the lumbar generators, they contribute to coordinated rhythmic activity along the entire spinal cord of a quadrupedal locomoting mammal.

Action Potentials↗
PubMed2002

Studies on fetal forelimb movements by using a wrist actigraph in sheep.

The purpose of this study was to investigate whether an actigraph can be a tool for measuring fetal movements in sheep. Actiwatches were placed on a fetal forelimb and the maternal uterine wall in near-term pregnant sheep. No significant correlation was found between fetal and maternal activity counts for periods of 1 min. The patterns of fetal activity counts were characterized by ultradian rhythms, with bursts of activity every 20-30 min; however, there was no evidence of diurnal changes in fetal activity counts. The results suggest that fetal movements can be measured by using an actigraph in chronically prepared fetal sheep.

Animals↗
PubMed2000

X-ray kinematic analysis of forelimb movements during target reaching and food taking in the cat.

We have used a three-dimensional X-ray cinematographic approach to investigate the kinematics of the forelimb during target reaching and food taking in five cats. Measurements of the trajectory of the limb during the reaching movement showed that the movement paths of the metacarpophalangeal joint (MCP) and the wrist were sigmoidal with a long nearly linear segment. The elbow followed a bent movement path with maximal inflection in the middle. The path of the humerus had an ascending parabola-like characteristic. The velocity profiles of the MCP and wrist were nearly bell-shaped and skewed to the left, whereas the profiles of the elbow joint were more or less double peaked with the second peak occurring 60-40 ms before object contact. Several different velocity peaks reflecting specific aspects of the task existed when the bell-shaped velocity profiles were divided in their vectorial components. Angular motion of the elbow consisted of a flexion-extension sequence during the reach and a flexion during the subsequent retraction. After an initial flexion during lift-off the wrist was extended. It kept this extended position during orienting towards the food container. During the retraction phase it was further extended. The angle between the wrist axis and the parasagittal plane changed during the movement. It first increased, then decreased during the last 100 ms before the object was reached. During the retraction it increased again to support the object weight against gravity. The position of the wrist was established by radio-ulnar supination and movements of the whole arm around the shoulder joint. We hypothesize that the position of the wrist axis is the controlled variable during protraction and retraction, regardless of whether it is achieved by radio-ulnar supination or by movements around the shoulder.

Animals↗
PubMed2000

Distribution of spinocerebellar Purkinje cell responses to passive forelimb movements in the rat.

We recorded Purkinje cell activity throughout the spinocerebellum of anaesthetized rats while imposing circular passive movements to the unrestrained forelimb. The aim was to understand the type of processing of sensory information occurring at the level of the cerebellar cortex, on the basis that precerebellar sensory neurons have been shown to represent whole limb movement parameters better than single joint movements. We observed that neurons representing sensory aspects of arm movements were scattered throughout the spinocerebellar cortex without a distinct segregation from those that did not respond, albeit the relative density of responsive and unresponsive neurons was quite variable and depended on the area of the cortex. Furthermore, Purkinje cells that responded significantly to the arm movement cycles all showed the same response pattern consisting of a firing rate increase during the downward extension of the arm. These results are discussed as suggesting a coordinate framework for the representation of proprioceptive information in the cerebellum congruent to that observed for encoding motor parameters.

Animals↗
PubMed2000

The arterial supply to the digits of the forelimb in the Bactrian camel (Camelus bactrianus).

The arterial supply of the digits of the forelimb of the Bactrian camel is described. The arteries supplying the digits were the palmar metacarpal and common palmar digital arteries III. The palmar metacarpal artery III was the continuation of the deep medial proximal metacarpal branch which was derived from the medial branch of the radial artery. It gave rise to a nutrient branch, medial branch, lateral branch and distal perforating palmar branch at the proximal end of the distal sixth of the cannon bone (fused third and fourth metacarpal bones). The common palmar digital artery III was the continuation of the median artery, which divided into medial and lateral branches. The medial branch of common palmar digital artery III which occasionally arose from the axial palmar proper digital artery III, after giving rise to the axial proximal proximal phalangeal branch, divided into the axial and abaxial palmar proper digital arteries III. The axial palmar proper digital artery III gave off the dorsoaxial distal proximal phalangeal, dorsoaxial proximal middle phalangeal, dorsoaxial distal middle phalangeal, palmoaxial middle phalangeal, palmoaxial distal phalangeal, dorsoaxial distal phalangeal branches, coronal artery and some digital tori branches. The abaxial palmar proper digital artery III gave rise to the abaxial proximal proximal phalangeal, dorsoabaxial distal proximal phalangeal, dorsoabaxial middle phalangeal, palmoabaxial middle phalangeal, palmoabaxial distal phalangeal, dorsoabaxial distal phalangeal branches, coronal artery and some digital tori branches. The lateral branch of the common palmar digital artery III in its origin, course, branching pattern and supply in the fourth digit was similar to the medial branch of common palmar digital artery III in the third digit.

Adaptation, Physiological↗
PubMedDate not supplied

An in vivo equine forelimb model for short-term recording of peak isometric force in the superficial and deep digital flexor muscles.

OBJECTIVE: To develop and test an experimental model for in vivo short-term recording of peak isometric forces of the digital flexor muscles in the forelimb of adult horses. STUDY DESIGN: In vivo experimental study. SAMPLE POPULATION: Four healthy, anesthetized, adult Thoroughbred horses (3 to 7 years old; 527 +/- 87 kg) METHODS: In dorsal recumbency, ulnar and median nerves were exposed and instrumented with insulated bipolar cuff stimulation electrodes for later connection to an electrical stimulator. In left lateral recumbency, a biplanar fixator was applied to the right humerus and a custom-made, rigid, aluminum frame connected to it, to allow loading of muscles distal to the fixator. Threaded transfixation pins through the radial and metacarpal condyles were clamped to the rigid frame so that the humerus, radius, ulna, and metacarpus were fixed in position. Each digital flexor muscle insertion tendon was transected just above the metacarpophalangeal joint, extracted from the carpal canal, and secured in a metal clamp positioned at the distal myotendinous (MT) junction. Distally, the clamp was connected in series to a load cell and a pneumatic actuator to record force and to maintain muscle length during nerve stimulation. A linear potentiometer was connected in parallel to the actuator to record MT junction position. Initial trials were conducted to identify median and ulnar nerve stimulation variables to achieve maximal muscle contraction. Isometric contractions were performed at different muscle lengths and peak forces registered during 3 seconds of supramaximal dual (ulnar and median) nerve stimulation. RESULTS: A stimulation voltage of 2.5 to 5.0 V at 50 Hz usually produced maximal force for both the superficial digital flexor (SDF) and deep digital flexor (DDF) muscles. Single ulnar and median nerve stimulation elicited force development not only in the DDF muscle but also in the SDF muscle. At voltages higher than 1 V, normalized force was greatest with combined median and ulnar nerve stimulation for both the DDF and SDF muscles; however, normalized force was greater for median nerve stimulation than ulnar nerve stimulation in the DDF muscle, and the opposite relationship was observed for the SDF muscle. Final recording of dual supramaximal nerve stimulation of SDF and DDF muscles resulted in peak isometric forces of 716 +/- 192 N and 1,577 +/- 203 N, respectively. CONCLUSIONS: The instrumentation technique and experimental protocol enabled recording of peak isometric forces in the SDF and DDF muscles of anesthetized adult horses. CLINICAL RELEVANCE: Studies using this model will improve knowledge of SDF and DDF muscle mechanics with insight to functional implications of the complex architecture of these muscles. Knowledge of the dynamic performance of the SDF and DDF muscles would also be useful for the development of new treatment strategies for flexor deformities and tendon injuries in horses.

Animals↗
PubMed1995

Axial skeleton homeosis and forelimb malformations in Hoxd-11 mutant mice.

The Hoxd-11 gene was disrupted by homologous recombination in embryonic stem cells. We found that Hoxd-11-/- mutant mice are viable and display homeotic transformations of their sacral vertebrae, while their forelimbs present abnormalities of some metacarpals and of the first row of carpal bones. These results are discussed in the light of current models of tetrapod axial skeleton and limb patterning.

Animals↗
PubMed1999

On the relation of rat's external cuneate activity to global parameters of forelimb posture.

Using anesthetized adult rats, we studied the relationships between the activity of cells belonging to the external cuneate nucleus (ECN) and passive forelimb positions. In essence, we sought to distinguish between a representation of limb position based on local limb parameters (individual joint angles, for example) or a representation based on more global parameters such as the length and the orientation of the limb axis. Using multivariate regression analyses we found that most neurons showed strong linear relationships with the length and the orientation of the limb axis. Relationships to individual joint angles were, instead, rather weak and in most cases not significant. This result implies an extensive integration of sensory information at the level of second order sensory neurons.

Animals↗
PubMed2002

Kinematic features of passive forelimb movements and rat cuneate neuron discharges.

We examined the role of main and external cuneate nuclei neurons in processing sensory information during forelimb passive movement. We recorded activity of neurons using circular and figure-eight trajectories, at different speeds, in anaesthetized rats. A multivariate regression analysis was performed to correlate neural discharge to movement direction and speed, the two components of the velocity vector. We found that the activity of the majority of cuneate neurons related to passive movement velocity and that the directional component of the velocity vector accounted for a larger fraction of the variability in the firing rate than the scalar component (speed). These results indicate that cuneate cells can process whole limb afferent information to elaborate a representation of the movement velocity vector.

Algorithms↗
PubMed1985

A horseradish peroxidase study of motorneuron pools of the forelimb and hindlimb musculature of the axolotl.

Motorneuron pools innervating axolotl limb muscles have been investigated by using the retrograde neuronal tracer horseradish peroxidase. Four muscles in the forelimb (biceps, anconeus, flexor digitorum and extensor digitorum) and four functionally equivalent muscles in the hindlimb (puboischiotibialis, iliotibialis, flexor digitorum and extensor digitorum) were studied. Motorneuron pools were characterized by using four criteria: position in the rostrocaudal axis; position of the median in the rostrocaudal axis; number of labelled cells; position of cells in the transverse plane of the spinal cord. Each pool was uniquely defined by the four characteristics, although overlap was found between pools. Two types of motorneuron were found in each pool, distinguished on the basis of size, shape and position in the spinal cord. The first type constituted the majority of cells in a pool, and occupied different positions in the transverse plane for each muscle. The second type was less common and always occupied a characteristic medial ventral position. These data will allow an assay of correct or incorrect innervation in experiments on the regeneration of specific neuromuscular connections in these animals.

Ambystoma↗
PubMed1989

Descriptive and comparative myology of the forelimb of the babirusa (Babyrousa babyrussa L. 1758).

A description is given of the anatomy of the extrinsic and intrinsic muscles of the forelimb of the babirusa (Babyrousa babyrussa, L. 1758). Three adult animals, two males and a female were dissected and the results compared with the previously published information. Significant differences were found between the accounts, and these were analysed within the context of material availability and advances in anatomical nomenclature. Comparisons made with published descriptions of the pig (Sus scrofa) showed that the muscular anatomy of the two species is very similar. Four structures are present in the babirusa but not in the pig; the M. pronator teres is completely tendinous, a tendon branch from the Caput craniale m. extensor digitorum lateralis anastomoses with the tendon of the Caput intermedium m. extensor digitorum communis to the fourth digit, there is an additional small deep portion of the M. supraspinatus and a bundle of fibres from the M. pectoralis profundus inserts on the intersectio clavicularis. Four structures present in the pig but not the babirusa are an additional insertion from the M. cleido-occipitalis into the raphe of the neck, an extra medial insertion of the M. infraspinatus, the accessory tendinous origin of the M. flexor digitorum profundus and the ulnar head of the M. flexor carpi ulnaris.

Anatomy, Comparative↗
PubMed2006

Radiographic evolution of the forelimb digit in Ardenner horses from weaning to 28 months of age and its clinical significance.

Ossification of collateral cartilages is a common radiographic finding in draught horses and indication of a high frequency of interphalangeal osteo-arthropathy have been found in Ardenner horses. This study first aimed at following the evolution of the digits of the forelimbs on radiographic images in a group of 32 Ardenner horses from weaning to 852 +/- 19 days and, secondly, at evaluating the clinical significance of the observed radiographic changes. At 250 +/- 21 days, only 23% of the horses presented a small separate ossification centre of collateral cartilages above the level of the distal sesamoid bone or at the level of the proximal half of the middle phalanx. At 852 +/- 19 days, 100% of the horses presented an ossification of collateral cartilages but at different stages and grades. The presence and the extent of the ossification of the lateral cartilages were not significantly associated with lameness. Phalanges changes appeared at the average age of 1 year and they were represented by entheseophytes on the dorsal surface of the middle and distal phalanges. The frequency of affected horses increased with age as well as the size of the entheseophytes. This may reflect mechanical stresses applied to the interphalangeal joints. A significant association with the presence of lameness was pointed out. The presence and the severity of phalanges changes could be of importance, in combination with a clinical examination, in improving the selection of horses able to assume work and/or leisure activities.

Aging↗
PubMedDate not supplied

The effect of occlusive and semi-occlusive dressings on the healing of acute full-thickness skin wounds on the forelimbs of dogs.

This project compared the effects of hydrocolloid (HC) and hydrogel (HG) occlusive dressings and a polyethylene (PE) semi-occlusive dressing on the healing of acute full-thickness skin wounds on the forelimbs of 10 dogs. All treatments resulted in a similar degree of healing at postoperative days 4 and 7. No significant differences existed in the number of wounds that were more than 90% healed at postoperative day 28 between the group treated with the HG dressing and the group treated with the PE dressing. There were significantly fewer wounds more than 90% healed at postoperative day 28 in the group treated with the HC dressing. Wounds under the HG dressing had the largest mean percentage of contraction at postoperative days 21 and 28. Wounds under the HG dressing also had the largest contraction/re-epithelialization ratio (postoperative days 21 and 28) compared with wounds under the PE and HC dressings. Wounds under the PE dressing had a significantly higher mean percentage of re-epithelialization than wounds under both occlusive dressings on postoperative days 14, 21, and 28. Wounds under the two occlusive dressings had exuberant granulation tissue present more often than wounds under the PE dressing. The two occlusive dressings had significantly higher bacterial counts on wounds compared with wounds under the PE dressing; analysis of variance (ANOVA), P = .0008. Wounds under the HC dressing showed the poorest healing in all parameters.

Animals↗
PubMedDate not supplied

An in vitro biomechanical comparison of two fixation methods for transverse osteotomies of the medial proximal forelimb sesamoid bones in horses.

OBJECTIVE: This study compared the mechanical properties of the normal intact suspensory apparatus and two methods of fixation for repair of transverse, midbody fractures of the proximal sesamoid bones of adult horses: transfixation wiring (TW) and screws placed in lag fashion (LS). STUDY DESIGN: An in vitro, paired study using equine cadaver limbs mounted in a loading apparatus was used to test the mechanical properties of TW and LS. ANIMAL OR SAMPLE POPULATION: Seventeen paired (13 repaired, 4 normal) equine cadaver limbs consisting of the suspensory apparatus third metacarpal bone, and first and second phalanges. METHOD: The two methods of repair and normal intact specimens were evaluated in single cycle-to-failure loading. Yield failure was defined to occur at the first notable discontinuity (>50 N) in the load-displacement curve, the first visible failure as evident on the videotape, or a change in the slope of the moment-fetlock angle curve. Ultimate failure was defined to occur at the highest load resisted by the specimen. Corresponding resultant force and force per kg of body weight on the suspensory apparatus, fetlock joint moment, and angle of fetlock dorsiflexion were calculated by use of specimen dimensions and applied load. These were compared along with specimen stiffness, and ram displacement. RESULTS: Load on the suspensory apparatus, load on the suspensory apparatus per kg of body weight, moment, applied load, and angle of fetlock dorsiflexion at yield failure were significantly greater for the TW-repaired than for the LS-repaired specimens. A 3 to 5 mm gap was observed before yield failure in most TW-repaired osteotomies. CONCLUSIONS: Transfixation wiring provided greater strength to yield failure than screws placed in lag fashion in single cycle load-to-failure mechanical testing of repaired transverse osteotomized specimens of the medial proximal forelimb sesamoid bone.

Animals↗
PubMed1986

Projection of Ia and Ib afferents from forelimb muscles to the C3-C4 segments of the cat spinal cord.

Group Ia muscle spindle afferents were activated separately by small stretches applied to the tendons of antibrachial muscles in the forelimb in the cat. Group Ib tendon organ afferents were stimulated electrically after a selective increase of the threshold of the Ia afferents. Recordings of focal synaptic potentials were made in the C3-C4 segments in the medial part of the base of the dorsal horn. It has been found that both Ia and Ib afferents have monosynaptic connections with neurones in this medial region. Quantitatively, these two groups of afferents produced focal synaptic potentials of approximately the same size. The connections may be to inhibitory interneurones projecting to the C3-C4 propriospinal neurones, which are known to receive disynaptic IPSPs from group I muscle afferents.

Afferent Pathways↗
PubMed2005

Of all the nerve! A subcutaneous forelimb mass on a cat.

A 16-year-old, male, neutered cat had a 2.5 X 1.5 cm mass on the medial aspect of the right carpus. Cytologic examination of a fine-needle aspirate of the mass indicated a markedly pleomorphic population of plasmacytoid to histiocytic-appearing cells. The cytologic diagnosis was malignant neoplasia of probable mesenchymal or round cell origin. The right forelimb was surgically removed and the scapular, axillary, and prescapular lymph nodes were excised. Malignant fibrous histiocytoma was tentatively diagnosed histologically; however, the tumor cells subsequently were found to be negative for histiocytic (MAC 387, antitrypsin), T-cell (CD3), and B-lymphocyte (immunoglobulin light chains, Ly 5/CD45R) markers, and positive for glial fibrillary acidic protein, vimentin, and S-100. Based on the immunohistochemical results, the diagnosis was modified to malignant peripheral nerve sheath tumor (PNST). Six months after surgery, the cat was reported to be well and had no evidence of metastasis. PNSTs are rare tumors in cats, and are considered as synonymous with schwannomas, neurofibrosarcomas, and hemangiopericytomas. In this cat, the plasmacytoid and pleomorphic appearance of the PNSTcells in cytologic and histologic specimens was unusual, and made it difficult to reach an accurate diagnosis without immunocytochemistry.

Animals↗