Morphology of the shoulder musculature of the American kestrel,Falco sparverius (Aves), with implications for gliding flight

Summary The shoulder morphology of the American kestrel,Falco sparverius, was dissected with an emphasis on the morphological requirements for gliding flight. Kestrels are being used as a model for the study of gliding flight in a non-specialized gliding bird. The kestrel forelimb is relatively generalized in its construction, and does not appear to have any remarkable specializations for gliding. However, several structures found in specialized gliders/soarers which may contribute to gliding were also found in kestrels; these include the presence of a scapular anchor and pectoral muscle fibers inserting onto the tendon of the biceps brachii muscle. This paper is the prelude to an experimental study on the gliding flight in this species and may serve as a basis for future functional or taxonomic comparisons.Abbreviations BB M. biceps brachii - Br M. brachialis - C coracoid - C12 12th cervical vertebra - CBA M. coracobrachialis cranialis - CBC M. coracobrachialis caudalis - DMA M. deltoideus major pars cranialis - DMa M. deltoideus major - DMC M. deltoideus major pars caudalis - DMi M. deltoideus minor - ECU M. extensor carpi ulnaris - EDC M. extensor digitorum communis - EMR M. extensor metacarpi radialis - ES M. expansor secundariorum - EU M. ectopicondylo-ulnaris - F furcula - FAH Facies articularis humeralis - FASc Facies articularis scapularis - FASt Facies articularis sternalis - ECU M. flexor carpi ulnaris - FP Fascia pectoralis - H humerus - HCB humerocarpal band - HS Os humeroscapularc and adjacent shoulder ligaments - K sternal keel - LDA M. latissimus dorsi pars cranialis - LDC M. latissimus dorsi pars caudalis - LMS Ligamentous portion of membrana sternocoracoclavicularis - MC Membrana cristoclavicularis - MS Membrana sternocoracoclavicularis - N Notarium - PB M. tensor propatagialis pars brevis - PC pectoral crest of humerus - PL M. tensor propatagialis pars longa - PP M. pronator profundus - PPB M. pectoralis propatagialis brevis - PPL M. pectoralis propatagialis longus - PS M. pronator superficialis - PT M. pectoralis pars thoracicus - RP M. rhomboideus profundus - RS M. rhomboideus superficialis - SA scapular anchor - SB M. subscapularis - SBe M. subscapularis pars externa - SBi M. subscapularis pars interna - SC M. supracoracoideus - Sc scapula - SHA M. scapulohumeralis cranialis - SHC M. scapulohumeralis caudalis - SP M. serratus profundus - SSA M. serratus superficialis pars cranialis - SSC M. serratus superficialis pars caudalis - SSM M. serratus superficialis pars metapatagialis - ST M. sternocoracoideus - St sternum - SU M. subcoracoideus - Su M. supinator - Sy synsacrum - T M. triceps - TH M. triceps humeralis - TS M. triceps scapularis     

Die mechanik der syndactylen zehen von macropus und anderen beuteltieren und ihre verwendung als putzorgan

Ohne ZusammenfassungErklärung der abkürzungen Astr. Astragalus - C I–III Cuneiforme I–III. - Ca. Calcaneus. - cd.m.Sp. caudales, mediales Sprunggelenksband. - C.l. Caput laterale gastrocnemii. - C.m. Caput mediale gastrocnemii. - Cp.f. Caput fibulae. - cr.m.Sp. craniales, mediales Sprunggelenksband. - C.t. Crista tibiae. - D.I–V Digitus I–V. - d.m.S. Dorso-mediales Seitenband. - Fib. Fibula. - Gfl. C III Gelenkfläche mit dem Cuneiforme III. - Gfl.Cale. Gelenkfläche mit dem Calcaneus. - Gefl.Cb. Gelenkfläche mit dem Cuboid. - Gfl.Mt. IV Gelenkfläche mit dem Metatarsale IV. - l.S. laterales Seitenband. - M.add. V Muse. adductor digiti V. - M.e.h.l. Musc. extensor hallucis longus. - M.e.l. Musc. extensor longus digitorum. - M.e.l. IV Musc. extensor longus digiti IV. - M.e.l. II–V Musc. extensor longus digitorum II–V. - M.e.l. II, III Musc. extensor longus digitorum II, III. - M.fl.br. II–V Musc. flexor brevis digiti II–V. - M.fl.d.p.prof. Muse. flexor digitorum pedis profundus. - M.l. Margo lateralis tibiae. - Mm.l. Musculi lumbricales. - M.p.l. Musc. peronaeus longus. - M.p. IV Musc. peronaeus digiti IV. - M.p. V Musc. peronaeus digiti V. - M.p.t. Musc. peronaeus tertius. - M.pl. Muse. plantaris (= Musc. fl. dig. ped. sublimis). - M.pl.l. lateraler Abzweig der Plantarissehne. - M.popl. Musc. popliteus. - M.s. Muse. soleus. - M.t.a. Muse. tibialis anticus. - M.t.p. Musc. tibialis posticus. - M.tric.sur.C.l. Musc. triceps surae, Caput laterale. - M.tric.sur.C.m. Musc. tricepssurae, Caput mediate. - Mt I-Mt V Metatarsale I–V. - Mt.Ph.Gk. Metatarso-Phalangealgelenk. - N. Naviculare. - o.l. Sp. oberes laterales Sprunggelenksband. - Ph. I-Ph. III Phalanx I–III. - pl.m.S. plantares mediales Seitenband. - Ssb.Mt.Ph. Gk. Sesambeine des Metatarso-Phalangealgelenkes. - S.t.p. Sehne des Musc. tibialis posticus. - u.l.Sp. unteres laterales Sprunggelenksband. - U.M.p. IV Ürsprungszone des Muse. paronaeus IV. - I–V Strahlen des Fußskelettes.     

Wrist tendon moment arms: Quantification by imaging and experimental techniques

Subject-specific musculoskeletal models require accurate values of muscle moment arms. The aim of this study was to compare moment arms of wrist tendons obtained from non-invasive magnetic resonance imaging (MRI) to those obtained from an in vitro experimental approach. MRI was performed on ten upper limb cadaveric specimens to obtain the centrelines for the flexor carpi radialis (FCR), flexor carpi ulnaris (FCU), extensor carpi radialis longus (ECRL), extensor carpi radialis brevis (ECRB), extensor carpi ulnaris (ECU), and abductor pollicis longus (APL) tendons. From these, the anatomical moment arms about each of the flexion-extension (FE) and radioulnar deviation (RUD) axes of the wrist were calculated. Specimens were mounted on a physiologic wrist simulator to obtain functional measurements of the moment arms using the tendon excursion method. No differences were observed between anatomical and functional values of the FE and RUD moment arms of FCR, ECRL and ECRB, and the RUD moment arm of ECU (p > .075). Scaling the anatomical moment arms relative to ECRB in FE and ECU in RUD reduced differences in the FE moment arm of FCU and the RUD moment arm of APL to less than 15% (p > .139). However, differences persisted in moment arms of FCU in RUD, and ECU and APL in FE (p < .008). This study shows that while measurements of moment arms of wrist tendons using imaging do not always conform to values obtained using in vitro experimental approaches, a stricter protocol could result in the acquisition of subject-specific moment arms to personalise musculoskeletal models.     

The importance of abductor pollicis longus in wrist motions: A physiological wrist simulator study

The abductor pollicis longus (APL) is one of the primary radial deviators of the wrist, owing to its insertion at the base of the first metacarpal and its large moment arm about the radioulnar deviation axis. Although it plays a vital role in surgical reconstructions of the wrist and hand, it is often neglected while simulating wrist motions in vitro. The aim of this study was to observe the effects of the absence of APL on the distribution of muscle forces during wrist motions. A validated physiological wrist simulator was used to replicate cyclic planar and complex wrist motions in cadaveric specimens by applying tensile loads to six wrist muscles – flexor carpi radialis (FCR), flexor carpi ulnaris, extensor carpi radialis longus (ECRL), extensor carpi radialis brevis, extensor carpi ulnaris (ECU) and APL. Resultant muscle forces for active wrist motions with and without actuating the APL were compared. The absence of APL resulted in higher forces in FCR and ECRL – the synergists of APL – and lower forces in ECU – the antagonist of APL. The altered distribution of wrist muscle forces observed in the absence of active APL control could significantly alter the efficacy of in vitro experiments conducted on wrist simulators, in particular when investigating those surgical reconstructions or rehabilitation of the wrist heavily reliant on the APL, such as treatments for basal thumb osteoarthritis.     

Functional anatomy of the hand of Australopithecus africanus

The Sterkfontein hand bones, attributed to Australopithecus africanus, were analysed to determine potential hand function of the power grip type of this species. The metacarpus is as stable as that of modern humans, as indicated by the depth of the groove on the base of metacarpal 2, the styloid process of metacarpal 3, the base articular surface areas, and the ligament markings on the bases of the metacarpals. The flexion and rotation of metacarpal 5 might have been less than that of modern humans, due to a more marked ventral articular lip on the base. The metacarpus acts as a lever, acting in various planes. The extensor carpi ulnaris and extensor carpi radialis longus muscles were probably better developed than in modern humans. The extensor carpi radialis brevis and flexor carpi radialis muscles would probably have been as well developed as in modern humans. None of the long tendons have a mechanical disadvantage as compared to modern humans. The metacarpals have a high robusticity index. The proximal phalanges show some midshaft swelling, slightly greater curvature than in modern humans, and some side to side bowing: pongid features. The fibrous flexor sheath markings are well developed, but resemble those of modern humans rather than those of the pongids. A single middle phalanx resembles that of modern humans, and has well developed ridges for insertion of the flexor digitorum superficialis muscle. The distal phalanx of the thumb has a well developed region for insertion of the flexor pollicis longus muscle, and has a mechanical advantage over modern humans for action of this muscle at the interphalangeal joint. The features indicate that the hand of A. africanus was well adapted to powerful hand use, as in hammering, striking, chopping, scraping, and gouging actions, as well as for throwing and climbing activities.     

Differentiation of fiber types in wing muscles during embryonic development: effect of neural tube removal

The embryonic precursors of the avian slow (type I and III) and fast (type II) fibers can be distinguished from each other early in muscle formation (stage 28, V. Hamburger and H. L. Hamilton, J. Morphol, 88, 49-92, 1951) on the basis of the differential sensitivity of their myosin ATPases. To test the neural dependence of fiber type differentiation, the source of motor innervation was eliminated by excision of the brachial neural tube at stages 16-18 before muscles are innervated. Removal of the brachial neural tube did not affect the number of primary myotubes in a sample muscle of the forelimb (ulnimetacarpalis dorsalis, UMD) up until stage 36. Myosin ATPase staining at a variety of pHs revealed the typical patterns of fiber types in muscles of neural-tube free embryos in stages 35-37. These muscles included the anterior latissimus dorsi, brachialis, and UMD which showed presumptive type III staining (type IIIEMB), the pronator superficialis and flexor carpi ulnaris which showed embryonic type II staining (type IIEMB), and the triceps brachii muscles which showed characteristic arrangements of both type IEMB and type IIEMB fibers. The normal patterns of type IEMB and type IIEMB myotubes were also seen in muscles containing a heterogeneous mixture of fiber types such as the biceps brachii, extensor metacarpi radialis, and adductor indicis muscles, although the intensity of acid-stable ATPase staining of the type IEMB myotubes in these muscles was lower than in innervated muscles. It is concluded that the earliest differentiation of muscle fiber types is independent of the nervous system.     

Hindlimb myology of the monk parakeet (Aves,Psittaciformes)

We studied the hindlimb myology of the monk parakeet (Myiopsitta monachus). Like all parrots, it has zygodactyl feet enabling perching, climbing, hanging, moving easily among trees, and handling food. Muscles were described and weighed, and physiological cross‐sectional area (PCSA) of four flexors and one extensor was calculated. In comparison to other muscles, the M. tibialis cranialis and the M. fibularis brevis show increased development and high PCSA values, and therefore, large potential force production. Also, a large proportion of muscle mass was involved in flexing the digits. We hypothesize that these muscle traits are associated with the arboreal locomotion and food manipulation habits. In the monk parakeet, the M. extensor digitorum longus sends a branch to the hallux, and the connection between the M. flexor digitorum longus and the M. flexor hallucis longus is type I (Gadow's classification). We reaffirm the presence of the M. ambiens as a plesiomorphic condition that disappears in most members of the order. Among Psittaciformes, the M. fibularis brevis is stronger and the M. fibularis weaker in arboreal species than in basal terrestrial ones (e.g., Strigops). J. Morphol. 275:732–744, 2014. © 2014 Wiley Periodicals, Inc.     

Beitrag zur topographischen anatomie der eingeweide des Huhnes

Ohne ZusammenfassungBezeichnungen der Abbildungen A. br. Arteria brachiocephalica sin. - A. car. Arteria carotis comm. sin. - A. isch. Arteria ischiadica - A. subcl. Arteria subclavia sin. - Caec. Caecum - Cav. p. Cavum pericardii - Ce. abd. Cella abdominalis dextr. et sin. - Ce ax. Cella axillaris dextra - Ce cerv. Cellae cervicales - Ce corac. Cella coracoidalis - Ce pelv. Cella pelvina sinistra - Ce th. a. Cella thoracica ant. sinistra - Ce th. p. Cella thoracica post. dextra - C. 2–7. 2.-7. Rippe - D. Ductus cysticus et hepatoentericus (Gallengänge) - For. isch. Foramen ischiadicum - For. obt. Foramen obturatum - Il. Ileum - Lig. f. Ligamentum falciforme - Lig. triang. Ligamentum triangulare dextrum et sin. - Mesot. Mesotubarium - M. d. Musculi diaphragmatici - M. st. Muse. sternotrachealis dextr. - N. Nische des Hauptbauchfellraumes - N. isch. Nervus ischiadicus - Ost. c. a. Ostium cellae abdom. - Ost. c. th. Ostia pulm. cell. thorac. - Perit. Kaudales Blindende des r. dors. Bauchfellraumes. - Pu. Pulmones - R. lat. Ramus lateralis sterni - R. med. Ramus medialis sterni - Tub. ut. Tuba uterina - V. cav. Vena cava anterior dextra - V. portae Vena portae - Ves. f. Vesica felleae - Vert. co. 1 l. Schwanzwirbel - Vert. s. 1 l. Kreuzwirbel - Vert. th. 3 u. 5 3. u. 5. Brustwirbel.     

Fatigue effect on cross-talk in mechanomyography signals of extensor and flexor forearm muscles during maximal voluntary isometric contractions

Objective:This paper presents the analyses of the fatigue effect on the cross-talk in mechanomyography (MMG) signals of extensor and flexor forearm muscles during pre- and post-fatigue maximum voluntary isometric contraction (MVIC).Methods:Twenty male participants performed repetitive submaximal (60% MVIC) grip muscle contractions to induce muscle fatigue and the results were analyzed during the pre- and post-fatigue MVIC. MMG signals were recorded on the extensor digitorum (ED), extensor carpi radialis longus (ECRL), flexor digitorum superficialis (FDS) and flexor carpi radialis (FCR) muscles. The cross-correlation coefficient was used to quantify the cross-talk values in forearm muscle pairs (MP1, MP2, MP3, MP4, MP5 and MP6). In addition, the MMG RMS and MMG MPF were calculated to determine force production and muscle fatigue level, respectively.Results:The fatigue effect significantly increased the cross-talk values in forearm muscle pairs except for MP2 and MP6. While the MMG RMS and MMG MPF significantly decreased (p<0.05) based on the examination of the mean differences from pre- and post-fatigue MVIC.Conclusion:The presented results can be used as a reference for further investigation of cross-talk on the fatigue assessment of extensor and flexor muscles’ mechanic.     

Proprioceptive feedback in locust kicking and jumping during maturation

Campaniform sensilla monitor the forces generated by the leg muscles during the co-contraction phase of locust (Schistocerca gregaria) kicking and jumping and re-excite the fast extensor (FETi) and flexor tibiae motor neurones, which innervate the leg muscles. Sensory signals from a campaniform sensillum on the proximal tibia were compared in newly moulted locusts, which do not kick and jump, and mature locusts which readily kick and jump. The activity pattern of FETi during co-contraction was mimicked by stimulating the extensor tibiae muscle. Less force was generated and the spike frequency of the sensory neurone from the sensillum was significantly lower in newly moulted compared to mature locusts. Depolarisation of both FETi and flexor motor neurones as a result of sensory feedback was consequently less in newly moulted than in mature locusts. The difference in the depolarisation was greater than the decrease in the afferent spike frequency suggesting that the central connections of the afferents are modulated. The depolarisation could generate spikes in FETi and maintain flexor spikes in mature but not in newly moulted locusts. This indicates that feedback from the anterior campaniform sensillum comprises a significant component of the drive to both FETi and flexor activity during co-contraction in mature animals and that the changes in this feedback contribute to the developmental change in behaviour.Abbreviations aCS anterior campaniform sensillum - ETi extensor tibiae - FETi fast extensor tibiae motor neurone - FlTi flexor tibiae - pCS posterior campaniform sensillum     

The distribution of gonadotropin-releasing hormone (GnRH) neurons and fibers throughout the chick brain (Gallus domesticus)

Summary Nerve fibers and perikarya containing gonadotropin-releasing hormone (GnRH-like) immunoreactivity were investigated in the brain of the three-week-old chick, Gallus domesticus using the technique of immunocytochemistry. Six major groups of perikarya were found to include the olfactory bulb, olfactory tubercle/lobus parolfactorius, nucleus accumbens, septal preoptic hypothalamic region (three sub-nuclei), lateral anterior thalamic nucleus and in and about the oculomotor complex. The immunostaining was unusual in the latter group, suggesting that the neurons may contain a GnRH-II like material. Immunoreactive fibers for GnRH were found throughout the entire brain extending from the olfactory bulbs to the caudal brainstem. Two anatomical areas, not emphasized in the past literature, which had distinct GnRH-like immunoreactivity, included the lateral anterior thalamic nucleus and the preoptic recess. The former included a group of GnRH perikarya that is also known to be a retino-recipient area while the latter contained neuronal terminals some of which appeared to be contacting the cerebrospinal fluid of the preoptic recess. An attempt was made to list all anatomical structures that contained or were juxta-positioned to sites that displayed immunoreactive perikarya and fibers including circumventricular organs.Abbreviations used in figure legends Ac Nucleus accumbens - Ap Archistriatum posterior - APH Area parahippocampalis - AVT Area ventralis (Tsai) - BO Bulbus olfactorius - CA Commissura anterior (rostralis) - CDL Area corticoidea dorsolateralis - CO Chiasma opticum - CP Commissura posterior - CPi Cortex piriformis - CPP Cortex praepiriformis - CT Commissura tectalis - CTz Corpus trapezoideum - EW Nucleus of Edinger-Westphal - FV Funiculus ventralis - GCt Substantia grisea centralis - GLv Nucleus geniculatus lateralis, pars ventralis - HD Hyperstriatum dorsale - HM Nucleus habenularis medialis - Hp Hippocampus - ICo Nucleus intercollicularis - IH Nucleus inferior hypothalami - IN Nucleus infundibuli hypothalami - IP Nucleus interpeduncularis - LA Nucleus lateralis anterior (rostralis) thalami - LHy Regio lateralis hypothalami - LPO Lobus parolfactorius - LSO Organum septi lateralis (lateral septal organ) - LT Lamina terminalis - ME Eminentia mediana - INT. Z Internal zone - EXT. Z External zone - ML Nucleus mamillaris lateralis - MM Nucleus mamillaris medialis - nBOR Nucleus opticus basalis (n. of basal optic root) - nCPa Nucleus commissurae pallii - N III Nervus oculomotorius - N V Nervus trigeminus - n V M Nucleus mesencephalicus nervi trigemini - OA Nucleus olfactorius anterior (rostralis) - OMdl Nucleus nervi oculomotorii, pars dorsomedialis - OMv Nucleus nervi oculomotorii, pars ventralis - OVLT Organum vasculosum laminae terminalis - P Glandula pinealis - PA Palaeostriatum augmentatum (caudate putamen) - PHN Nucleus periventricularis hypothalami - POM Nucleus praeopticus medialis - POMn Nucleus praeopticus medianus - POP Nucleus praeopticus periventricularis - PP Palaeostriatum primitivum - PT Nucleus praetectalis - PVN Nucleus paraventricularis magnocellularis - RPaM Nucleus reticularis paramedianus - RPR Recessus praeopticus - b, RPR Basal region, RPR - F, RPR Floor, RPR - R, RPR Roof, RPR - S Nucleus tractus solitarii - SCO Organum subcommissurale - SGP Stratum griseum periventriculare - SHL Nucleus subhabenularis lateralis - SL Nucleus septalis lateralis - SM Nucleus septalis medialis - SO Stratum opticum - SSO Organum subseptale - TO Tuberculum olfactorium - TIO Tractus isthmo-opticus - TPc Nucleus tegmenti pedunculopontinus, pars compacta (substantia nigra) - TrO Tractus opticus - TSM Tractus septomesencephalicus - VeD Nucleus vestibularis descendens - VeM Nucleus vestibularis medialis - VL Ventriculus lateralis - VLT Nucleus ventrolateralis thalami - VO Ventriculus olfactorius - V III Ventriculus tertius (third ventricle)     

Changes of agonist and synergist muscles activity during a sustained submaximal brake-pulling gesture

We analyzed the time course of changes in muscle activity of the prime mover and synergist muscles during a sustained brake-pulling action and investigated the relationship between muscle activity and braking force fluctuation (FF). Thirty-two participants performed a continuous fatiguing protocol (CFP) at 30% of maximal voluntary contraction (MVC) until failure. Surface electromyography was used to analyze root mean square (RMS) values in the flexor digitorum superficialis (FD), flexor carpi radialis (FC), extensor digitorum communis (ED), extensor carpi radialis (EC), brachioradialis (BR), biceps brachii (BB), and triceps brachii (TB). The FF and RMS in all muscles increased progressively (P<0.01) during the CFP, with sharp increments at time limit particularly in FD and FC (P<0.001). The RMS of the FD and FC were comparable to the baseline MVC values at time limit, in comparison to the other muscles that did not reach such levels of activity (P<0.003). The three flexor/extensor ratios used to measure coactivation levels decreased significantly (P<0.001). In contrast to RMS, MVC was still depressed at the minute 10 of recovery. The results suggest that the time limit was mainly constrained by fatigue-related mechanisms of the FD and FC but not by those of other synergist and antagonist muscles.     

New conditions and intraspecific variation of some muscles of hands and feet of Dendropsophus labialis (Peters, 1863) (Anura,Hylidae)

Systematics of frogs have been based on osteological and molecular characters; however, the morphology of the muscles of hands and feet has proven to be an important complement to these studies, but it has not been sufficiently studied. This study presents undescribed conditions based on the origin, insertion or arrangement of 18 muscles of hands and feet of Dendropsophus labialis, and intraspecific variation. Muscles of four specimens (two males and two females) were examined to observe both sides of each specimen determining new conditions, and comparing them with documented species of Dendropsophus. Four intraspecific variant categories were established: Minor, unique, explosive and mimicking. Mainly mimicking, explosive and unique variations were found. Our results show the need to expand intraspecific studies in more species of Dendropsophus and to assess its value in the phylogeny of the genus. The family Hylidae may be identifiable based upon the combination of character states of some of these muscles: the m. flexor indicis superficialis proprius and the group of tendines superficialis digitorum of hands and foot, the m. extensor brevis superficialis Digiti III of the hand, the m. extensor brevis superficialis Digiti IV in hands and the mm. extensores breves profundi Digiti III in hands.     

Crosstalk effect on surface electromyogram of the forearm flexors during a static grip task

The fraction of crosstalk was examined from the surface EMG signals collected from digit- and wrist-dedicated flexors with a blind signal separation (BSS) algorithm. Six participants performed static power grip tasks in a neutral posture at four different exertion levels of 25%, 50%, 75%, and 100% MVC. The signals were collected from the flexor digitorum superficialis, flexor digitorum profundus, flexor carpi radialis, palmaris longus, and flexor carpi ulnaris using a bipolar electrode configuration. The percentage of root mean square (RMS) was used as an amplitude-based index of crosstalk by normalizing the signals including crosstalk to those excluding crosstalk by the BSS algorithm for each %MVC exertion. The peak R² value of a cross-correlation function was also calculated as a correlation-based index of crosstalk for a group of forearm flexors by force level and algorithm application. The fraction of crosstalk ranged from 32% to 50% in the wrist-dedicated flexors and from 11% to 25% in the digit-dedicated flexors. Since surface EMG signals had such high levels of crosstalk, reduction methods like the BSS algorithm should be employed, as the BSS significantly reduced crosstalk in the forearm flexors 33% over all muscles and exertion levels. Thus, it is recommended that BSS be utilized to reduce crosstalk for the digit- and wrist-dedicated flexors during gripping tasks.     

Patterns of hind limb motor output during walking in the salamander Dicamptodon tenebrosus,with comparisons to other tetrapods

Based on similarity of motor patterns of lizards, crocodiles, birds and mammals, various authors have concluded that a number of homologous muscles across these taxa demonstrate neuromuscular conservatism. This hypothesis remains untested for more basal taxa. Therefore, a quantitative electromyographic study of the hind limb during treadmill walking (mean speed of 0.75 SVL/s) in the salamander Dicamptodon tenebrosus was undertaken. Muscles located ventrally on the hind limb become active just before foot placement on the substrate, and maintain activity through the first half of the stance phase. Dorsally located muscles begin activity at or just before the start of the swing phase, and fire through the first half of swing. Several muscles showed a secondary EMG burst during the stride. The second burst in most ventral muscles occurred in late stance. In all dorsal muscles with double bursts, the second burst occurred in the middle of stance. Comparison of electromyographic onset and offset values for Dicamptodon to those for presumed homologues in other tetrapods reveals similarity in activity patterns for all ventral and two dorsal muscles despite anatomical rearrangements, supporting the hypothesis of neuromuscular conservatism for some muscles but not others.Abbreviations BF biceps femoris muscle - CDF caudofemoralis muscle - CPIT caudalipuboischiotibialis muscle - Dist distal - EDC extensor digitorum communis muscle - EMG electromyogram - EXF extensor cruris et tarsi fibularis muscle - EXT extensor cruris tibialis muscle - FMFB femorofibularis muscle - FPC flexor primordialis communis muscle - Gastroc gastrocnemius muscle - ILFB iliofibularis muscle - ILFM iliofemoralis muscle - ILTA extensor iliotibialis pars anterior muscle - ILTP extensor iliotibialis pars posterior muscle - ISC ischiocaudalis muscle - ISF ischioflexorius muscle - ISFM ischiofemoralis muscle - ITCR iliotrochantericus cranialis muscle - ITM iliotrochantericus medius muscle - MG medial gastrocnemius muscle - PFM pubifemoralis muscle - PIFE puboischiofemoralis externus muscle - PIFI puboischiofemoralis internus muscle - PIT puboischiotibialis muscle - Prox proximal - PTB pubotibialis muscle - Sol soleus muscle - ST semitendinosus muscle - SVL snout-vent length     

The automating skeletal and muscular mechanisms of the avian wing (Aves)

The avian wing possesses the ability to synchronize flexion or extension of the elbow and wrist joints automatically. Skeletal and muscular mechanisms are involved in generating this phenomenon. The drawing-parallels action of the radius and ulna coordinates the movements of the forearm with the carpus. Movement of the radius along the length of the forearm isnot dependent on the shape disparity between the dorsal and ventral condyles of the humerus, nor is it generated by the shape of the dorsal condyle itself. Instead, shifting of the radius toward the wrist occurs during humeroulnar flexion when the radius, being pushed by muscles toward the ulna, is deflected off theIncisura radialis toward the wrist. Movement of the radius toward the elbow occurs during the latter stages of humeroulnar extension when, as the dorsal condyle of the humerus and the articular surface of the ulna's dorsal cup roll apart, the radius gets pulled by the humerus and its ligaments away from the wrist. Synchronization of the forearm with the manus is accomplished by twojoint muscles and tendons.M. extensor metacarpi radialis and the propatagial tendons act to extend the manus in unison with the forearm, whileM. extensor metacarpi ulnaris helps these limb segments flex simultaneously.M. flexor carpi ulnaris, in collaboration with the drawing-parallels mechanisms, flexes the carpus automatically when the elbow is flexed, thereby circumducting the manus from the plane of the wing toward the body. In a living bird, these skeletal and muscular coordinating mechanisms may function to automate the internal kinematics of the wing during flapping flight. A mechanized wing may also greatly facilitate the initial flight of fledgling birds. The coordinating mechanisms of the wing can be detected in a bird's osteology, thereby providing researchers with a new avenue by which to gauge the flight capabilities of avian fossil taxa.     

Quantitative analyses of cross-sectional shape of the distal radius in three species of macaques

I conducted quantitative analyses of the cross-sectional shape of the distal radial shaft in three species of macaques, which differ in locomotor behavior: semi-terrestrial Japanese macaques (Macaca fuscata), arboreal long tailed macaques (M. fascicularis), and relatively terrestrial rhesus macaques (M. mulatta). I took CT scans of the distal radial shafts of a total of 180 specimens at the level of the inferior radio-ulnar articulation. From each CT image, the periosteal outline of the radius was traced automatically by a digital imaging technique. I determined five points (landmarks) on the outline by developing a standardized morphometric technique. Bone surface lengths were measured by using these landmarks and their soft tissue correlates were investigated. The results of this study were as follows: (1) Semi-terrestrial M. fuscata has features that are approximately intermediate between those of the other two species. M. fuscata has a relatively small groove for M. abductor pollicis longus and a large groove for Mm. extensor carpi radialis longus et brevis. These characters resemble those of M. fascicularis. On the other hand, the ulnar notch of M. fuscata is relatively large, a character which is similar to that of M. mulatta. Moreover, compared to the other two macaques, the surface of the flexor muscles of M. fuscata is intermediate in size. (2) The more terrestrial M. mulatta has a relatively large groove for M. abductor pollicis longus and a small groove for Mm. extensor carpi radialis longus et brevis. Moreover, M. mulatta has a relatively large ulnar notch and a small surface for the flexor muscles. (3) The arboreal M. fascicularis has similar features to those of M. fuscata for the first and second relative size index. However, in the ulnar notch, M. fascicularis has a peculiar character and the surface for the flexor muscles is relatively large compared to those of the other two species. These results can be interpreted in terms of positional habits and presumed functional demands. A form-functional study by Lemelin and Schmitt also corroborates the interpretations of the present study. Thus, the distal region of the forearm strongly reflects muscular development and joint resultant force, and is an important region for investigating locomotor adaptations in primates. The present study reveals the possibility of using this type of morphometric analysis for reconstructing the positional behavior of fossil primates.     

Light-promoted changes in apoplastic K+ activity in the Samanea saman pulvinus,monitored with liquid membrane microelectrodes

The movement of Samanea saman (Jacq.) Merrill leaflets is a consequence of the re-distribution of K⁺ and anions between motor cells on opposite sides of the pulvinus. We used a K⁺-sensitive microelectrode to study dynamic changes in K⁺ transport through motor-cell membranes during and immediately after change in illumination. Potassium-ion-sensitive and reference microelectrodes were inserted into extensor or flexor tissue of a whole pulvinus in white light (WL). A brief pulse of red light (RL) followed by darkness (D) (a) increased K⁺ activity in the extensor apoplast, indicating K⁺ release by the protoplast; and (b) decreased K⁺ activity in the flexor apoplast, indicating K⁺ uptake by the protoplast. White light after 35–40 min D reversed K⁺ activity in the extensor apoplast to approximately its original value. Blue light substituted partially for WL in this regard. Potassium-ion activity in the flexor apoplast reverted to approximately its original value after 2 h, with or without white illumination. Our data support the hypothesis that K⁺ efflux from extensor cells and K⁺ uptake by flexor cells following a WLRLD transition occurs by way of K⁺ channels.Abbreviations L light - WL white light - RL red light - BL blue light - D darkness     

Fluorescence demonstration of a cathepsin H-like protease in cardiac, skeletal and vascular smooth muscles

Summary A cathepsin H-like enzyme was localized by histochemical techniques in cardiac muscle, extensor digitorum longus and soleus skeletal muscles, and vascular smooth muscle. Using the specific exopeptidase activity of this enzyme against the substrate arg-4-methoxy--naphthylamide, valid histochemical assay conditions were developed. More fluorescent granules were observed in cardiac muscle than in the soleus and about equal amounts in vascular smooth muscle and the extensor digitorum longus. The reaction rate was enhanced by chloride ions and inhibited by 1mm p-chloromercuribenzoate. The maximal activity was observed between pH 5.5 and 6.0. Chemical fixation with periodate-lysine-paraformaldehyde preserved a small amount of enzymatic activity.