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Brachii Muscle (brachii + muscle)
Kinds of Brachii Muscle Selected AbstractsExcitatory synaptic potentials in spastic human motoneurons have a short rise-timeMUSCLE AND NERVE, Issue 1 2005Nina L. Suresh PhD Abstract This study assessed whether changes in size or time-course of excitatory postsynaptic potentials (EPSPs) in motoneurons innervating spastic muscle could induce a greater synaptic response, and thereby contribute to reflex hyperexcitability. We compared motor unit (MU) firing patterns elicited by tendon taps applied to both spastic and contralateral (nonspastic) biceps brachii muscle in hemiparetic stroke subjects. Based on recordings of 115 MUs, significantly shortened EPSP rise times were present on the spastic side, but with no significant differences in estimated EPSP amplitude. These changes may contribute to hyperexcitable reflex responses at short latency, but the EPSP amplitude changes appear insufficient to account for global differences in reflex excitability. Muscle Nerve, 2005 [source] Functional anatomy of the olecranon process in hominoids and plio-pleistocene homininsAMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY, Issue 4 2004Michelle S.M. Drapeau Abstract This study examines the functional morphology of the olecranon process in hominoids and fossil hominins. The length of the bony lever of the triceps brachii muscle (TBM) is measured as the distance between the trochlear articular center and the most distant insertion site of the TBM, and olecranon orientation is measured as the angle that this bony lever makes with the long axis of the ulna. Results show that Homo, Pan, Gorilla, most monkeys, and the Australopithecus fossils studied have similar relative olecranon lengths. Suspensory hominoids and Ateles have shorter olecranons, suggesting, in some instances, selection for greater speed in extension. The orientation that the lever arm of the TBM makes with the long axis of the ulna varies with preferred locomotor mode. Terrestrial primates have olecranons that are more posteriorly oriented as body size increases, fitting general models of terrestrial mammalian posture. Arboreal quadrupeds have more proximally oriented lever arms than any terrestrial quadrupeds, which suggests use of the TBM with the elbow in a more flexed position. Olecranon orientation is not consistent in suspensory hominoids, although they are all characterized by orientations that are either similar or more posterior than those observed in quadrupeds. Homo and the fossils have olecranons that are clearly more proximally oriented than expected for a quadruped of their size. This suggests that Homo and Australopithecus used their TBM in a flexed position, a position most consistent with manipulatory activities. Am J Phys Anthropol, 2003. © 2003 Wiley-Liss, Inc. [source] Modulation of internal model formation during force field-induced motor learning by anodal transcranial direct current stimulation of primary motor cortexTHE JOURNAL OF PHYSIOLOGY, Issue 12 2009Timothy Hunter Human subjects can quickly adapt and maintain performance of arm reaching when experiencing novel physical environments such as robot-induced velocity-dependent force fields. Using anodal transcranial direct current stimulation (tDCS) this study showed that the primary motor cortex may play a role in motor adaptation of this sort. Subjects performed arm reaching movement trials in three phases: in a null force field (baseline), in a velocity-dependent force field (adaptation; 25 N s m,1) and once again in a null force field (de-adaptation). Active or sham tDCS was directed to the motor cortex representation of biceps brachii muscle during the adaptation phase of the motor learning protocol. During the adaptation phase, the global error in arm reaching (summed error from an ideal trajectory) was similar in both tDCS conditions. However, active tDCS induced a significantly greater global reaching (overshoot) error during the early stage of de-adaptation compared to the sham tDCS condition. The overshoot error may be representative of the development of a greater predictive movement to overcome the expected imposed force. An estimate of the predictive, initial movement trajectory (signed error in the first 150 ms of movement) was significantly augmented during the adaptation phase with active tDCS compared to sham tDCS. Furthermore, this increase was linearly related to the change of the overshoot summed error in the de-adaptation process. Together the results suggest that anodal tDCS augments the development of an internal model of the novel adapted movement and suggests that the primary motor cortex is involved in adaptation of reaching movements of healthy human subjects. [source] Three-headed biceps brachii muscle associated with duplicated musculocutaneous nerveCLINICAL ANATOMY, Issue 5 2005Marwan F. Abu-Hijleh Abstract A unilateral three-headed biceps brachii muscle coinciding with an unusual variant of the musculocutaneous nerve was found during routine dissection of a 79-year-old male cadaver. The supernumerary bicipital head originated from the antero-medial surface of the humerus just beyond the insertion of the coracobrachialis, and inserted into the conjoined tendon of biceps brachii. Associated with this muscular variant was a duplicated musculocutaneous nerve. The proximal musculocutaneous nerve conformed to the normal pattern only in its proximal part, and terminated after innervating the coracobrachialis and biceps brachii muscles. The distal musculocutaneous nerve arose from the median nerve in the lower arm, then passed laterally between the supernumerary bicipital head and the brachialis muscles, supplying both and terminating as the lateral cutaneous nerve of the forearm. The supernumerary bicipital head and the accompanying anomaly of the musculocutaneous nerve seem to be unique in literature. Clin. Anat. 18:376,379, 2005. © 2005 Wiley-Liss, Inc. [source] Supernumerary humeral heads of the biceps brachii muscle revisitedCLINICAL ANATOMY, Issue 3 2003Marc Rodríguez-Niedenführ Abstract Supernumerary humeral heads of the biceps brachii muscle were found in 27 (15.4%) of 175 cadavers. They were bilateral in five cadavers and unilateral in 22 (8 left, 14 right), giving a total of 32 examples in 350 arms (9.1%). Depending on their origin and location, the supernumerary heads were classified as superior, infero-medial, and infero-lateral humeral heads. Previous studies were reviewed using this classification. The infero-medial humeral head was observed in 31 of 350 (9%) arms and was therefore the most common variation. The superior humeral head was observed in five (1.5%). The infero-lateral humeral head was the least common variation, observed only in one (0.3%) of 350 arms. A biceps brachii with three heads was observed in 27 of 350 (7.7%) arms and with four heads in five (1.4%) arms. Clin. Anat. 16:197,203, 2003. © 2003 Wiley-Liss, Inc. [source] Two bellies of the coracobrachialis muscle associated with a third head of the biceps brachii muscleCLINICAL ANATOMY, Issue 5 2001Mostafa M. El-Naggar Abstract Reports that describe the abnormalities and complexities of the anatomy of the arm are important with regard to surgical approaches. This case study reports a combined abnormal form of the coracobrachialis and biceps brachii muscles of the left arm of an adult male cadaver that was detected during the educational gross anatomy dissections of embalmed cadavers. The coracobrachialis muscle demonstrated two bellies which formed shortly inferior to its origin from the coracoid process of the scapula. One belly inserted into the middle of the antero-medial surface of the humerus, whereas the other belly inserted into the medial head of the triceps brachii muscle. The musculocutaneous nerve passed between the two bellies, giving a separate branch to each. We suggest that the two bellies of the coracobrachialis muscle may represent the incompletely fused short heads of the ancestral muscle. The biceps brachii muscle showed a third head, which originated mainly from the antero-medial surface of the humerus and partially from an aponeurosis belonging to the medial head of the triceps brachii muscle. These observations were confined to the left upper limb and were not accompanied by any other abnormality. Clin. Anat. 5:379,382, 2001. © 2001 Wiley-Liss, Inc. [source] Incidence and morphology of the brachioradialis accessorius muscleJOURNAL OF ANATOMY, Issue 3 2001M. RODRÍGUEZ-NIEDENFÜHR A separate supernumerary muscle in the lateral cubital fossa originating from the humerus or brachioradialis and inserting into the radius, pronator teres or supinator muscle has been considered as a variation of the brachioradialis muscle (Dawson, 1822; Meckel, 1823; Lauth, 1830; Halbertsma, 1864; Gruber, 1868b; Testut, 1884; LeDouble, 1897; Spinner & Spinner, 1996). However, a similar description was used to report additional heads of the brachialis or biceps brachii muscles (Gruber, 1848; Wood, 1864, 1868; Macalister, 1864,66, 1966,69, 1875; Gruber, 1868a; Wolff-Heidegger, 1937). The innervation of these variant muscles would be a good tool to assign each variation to its associated muscle. Consequently, innervation by the radial nerve would indicate that it is a derivative of the humero,radialis group of muscles, while innervation by the musculocutaneous nerve would support it as a derivative of the anterior musculature of the arm (Rolleston, 1887; Lewis, 1989). However, no references to the innervation were found in the available literature. Therefore this study set out to establish the phylogenetic origin of the brachioradialis accessorius muscle and, with the help of its innervation, to determine its incidence and unreported detailed morphology. [source] Effect of elbow flexion contractures on the ability of people with C5 and C6 tetraplegia to liftPHYSIOTHERAPY RESEARCH INTERNATIONAL, Issue 2 2001Lisa Harvey Abstract Background and Purpose It is commonly assumed that minor elbow flexion contractures prevent people with C5,C6 tetraplegia and paralysis of the triceps brachii muscles from bearing full body weight through their upper limbs. The aim of the present study was to determine the effect of simulated bilateral elbow flexion contractures on the ability of these individuals to bear weight through their upper limbs and to determine whether full passive elbow extension is truly critical for lifting body weight. Method A biomechanical study was performed. Body weight lifted was measured under conditions that simulated bilateral elbow flexion contractures. Five people with motor complete C6 tetraplegia and one person with motor complete C5 tetraplegia, all with bilateral paralysis of the triceps brachii muscles, were recruited to the study. Subjects were fitted with bilateral elbow splints that restricted elbow extension but did not restrain elbow flexion nor prevent the elbow from collapsing, and were seated on an instrumented platform that measured vertical forces under the buttocks. Subjects pushed down through their hands and lifted under five different conditions, namely: with no elbow splints; with bilateral elbow splints adjusted to restrict elbow extension by 5,10°; by 15,20°; by 25,30° and with bilateral elbow splints adjusted to allow unrestricted movement of the elbow joint. Maximal weight lifted from under the buttocks, for each condition, was expressed in relation to weight under the buttocks during unsupported sitting (that is, ,seated body weight'). Results Subjects lifted progessively less weight from under their buttocks as passive elbow restriction was progressively restricted. However, one subject lifted all his seated body weight when elbow extension was restricted by 5,10° and another lifted all his seated body weight when elbow extension was restricted by 5,10° and 15,20°. Conclusions Minor elbow flexion contractures will not alone prevent people with tetraplegia and paralysis of the triceps brachii muscles from lifting. Full passive elbow extension is not critical for the performance of this task. Copyright © 2001 Whurr Publishers Ltd. [source] Three-headed biceps brachii muscle associated with duplicated musculocutaneous nerveCLINICAL ANATOMY, Issue 5 2005Marwan F. Abu-Hijleh Abstract A unilateral three-headed biceps brachii muscle coinciding with an unusual variant of the musculocutaneous nerve was found during routine dissection of a 79-year-old male cadaver. The supernumerary bicipital head originated from the antero-medial surface of the humerus just beyond the insertion of the coracobrachialis, and inserted into the conjoined tendon of biceps brachii. Associated with this muscular variant was a duplicated musculocutaneous nerve. The proximal musculocutaneous nerve conformed to the normal pattern only in its proximal part, and terminated after innervating the coracobrachialis and biceps brachii muscles. The distal musculocutaneous nerve arose from the median nerve in the lower arm, then passed laterally between the supernumerary bicipital head and the brachialis muscles, supplying both and terminating as the lateral cutaneous nerve of the forearm. The supernumerary bicipital head and the accompanying anomaly of the musculocutaneous nerve seem to be unique in literature. Clin. Anat. 18:376,379, 2005. © 2005 Wiley-Liss, Inc. [source] Two bellies of the coracobrachialis muscle associated with a third head of the biceps brachii muscleCLINICAL ANATOMY, Issue 5 2001Mostafa M. El-Naggar Abstract Reports that describe the abnormalities and complexities of the anatomy of the arm are important with regard to surgical approaches. This case study reports a combined abnormal form of the coracobrachialis and biceps brachii muscles of the left arm of an adult male cadaver that was detected during the educational gross anatomy dissections of embalmed cadavers. The coracobrachialis muscle demonstrated two bellies which formed shortly inferior to its origin from the coracoid process of the scapula. One belly inserted into the middle of the antero-medial surface of the humerus, whereas the other belly inserted into the medial head of the triceps brachii muscle. The musculocutaneous nerve passed between the two bellies, giving a separate branch to each. We suggest that the two bellies of the coracobrachialis muscle may represent the incompletely fused short heads of the ancestral muscle. The biceps brachii muscle showed a third head, which originated mainly from the antero-medial surface of the humerus and partially from an aponeurosis belonging to the medial head of the triceps brachii muscle. These observations were confined to the left upper limb and were not accompanied by any other abnormality. Clin. Anat. 5:379,382, 2001. © 2001 Wiley-Liss, Inc. [source] | |||||||||||||