Relationships Between Rounded Shoulder Posture and Biceps Brachii Muscle Length, Elbow Joint Angle, Pectoralis Muscle Length, Humeral Head Anterior Translation, and Glenohumeral Range of Motion

2017 ◽  
Vol 24 (2) ◽  
pp. 48-57
Author(s):  
Sil-ah Choi ◽  
◽  
Heon-seock Cynn ◽  
Ji-hyun Lee ◽  
Da-eun Kim ◽  
...  
Keyword(s):  
Range Of Motion ◽  
Humeral Head ◽  
Elbow Joint ◽  
Joint Angle ◽  
Biceps Brachii ◽  
Muscle Length ◽  
Pectoralis Muscle ◽  
Biceps Brachii Muscle ◽  
Anterior Translation

scholarly journals Muscle length and joint angle influence spinal but not corticospinal excitability to the biceps brachii across forearm postures

2019 ◽  
Vol 122 (1) ◽  
pp. 413-423 ◽  
Author(s):  
Davis A. Forman ◽  
Daniel Abdel-Malek ◽  
Christopher M. F. Bunce ◽  
Michael W. R. Holmes
Keyword(s):  
Isometric Contraction ◽  
Elbow Joint ◽  
Joint Angle ◽  
Biceps Brachii ◽  
Motor Evoked Potentials ◽  
Muscle Length ◽  
Elbow Flexion ◽  
Corticospinal Excitability ◽  
Biceps Brachii Muscle ◽  
Spinal Excitability

Forearm rotation (supination/pronation) alters corticospinal excitability to the biceps brachii, but it is unclear whether corticospinal excitability is influenced by joint angle, muscle length, or both. Thus the purpose of this study was to separately examine elbow joint angle and muscle length on corticospinal excitability. Corticospinal excitability to the biceps and triceps brachii was measured using motor evoked potentials (MEPs) elicited via transcranial magnetic stimulation. Spinal excitability was measured using cervicomedullary motor evoked potentials (CMEPs) elicited via transmastoid electrical stimulation. Elbow angles were manipulated with a fixed biceps brachii muscle length (and vice versa) across five unique postures: 1) forearm neutral, elbow flexion 90°; 2) forearm supinated, elbow flexion 90°; 3) forearm pronated, elbow flexion 90°; 4) forearm supinated, elbow flexion 78°; and 5) forearm pronated, elbow flexion 113°. A musculoskeletal model determined biceps brachii muscle length for postures 1–3, and elbow joint angles ( postures 4–5) were selected to maintain biceps length across forearm orientations. MEPs and CMEPs were elicited at rest and during an isometric contraction of 10% of maximal biceps muscle activity. At rest, MEP amplitudes to the biceps were largest during supination, which was independent of elbow joint angle. CMEP amplitudes were not different when the elbow was fixed at 90° but were largest in pronation when muscle length was controlled. During an isometric contraction, there were no significant differences across forearm postures for either MEP or CMEP amplitudes. These results highlight that elbow joint angle and biceps brachii muscle length can each independently influence spinal excitability. NEW & NOTEWORTHY Changes in upper limb posture can influence the responsiveness of the central nervous system to artificial stimulations. We established a novel approach integrating neurophysiology techniques with biomechanical modeling. Through this approach, the effects of elbow joint angle and biceps brachii muscle length on corticospinal and spinal excitability were assessed. We demonstrate that spinal excitability is uniquely influenced by joint angle and muscle length, and this highlights the importance of accounting for muscle length in neurophysiological studies.

Influence of Arm Positions on Emg-Reaction Time of the Biceps Brachii for Elbow Flexion and Forearm Supination

1984 ◽  
Vol 59 (1) ◽  
pp. 191-194 ◽  
Author(s):  
Reiji Taniguchi ◽  
Ryuichi Nakamura ◽  
Tatsuya Kasai
Keyword(s):  
Reaction Time ◽  
Elbow Joint ◽  
Biceps Brachii ◽  
Muscle Length ◽  
Elbow Flexion ◽  
Normal Subjects ◽  
Biceps Brachii Muscle ◽  
Prime Mover

The influence of starting positions of the arm on EMG-RTs of the biceps brachii muscle for elbow flexion and forearm supination was examined using 16 normal subjects. Two angles of the elbow joint, 45° and 110° flexion, and two positions of the forearm, 45° supination and 90° pronation, were used as the factorial combinations of all four. The EMG-RT for elbow flexion decreased in the order of 110° Pronation > 45° Pronation = 110° Supination > 45° Supination, and that for forearm supination decreased in the order of 45° Supination > 45° Pronation = 110° Supination > 110° Pronation. These results were kinesiologically interpreted that variations of EMG-RTs were based on the change in the number of synergic muscles participating in an intended movement and the muscle length of the prime mover at the start of the movement.

scholarly journals A Rare Anomaly of the Long Head of the Biceps Brachii Muscle

2018 ◽  
Vol 11 (1) ◽  
pp. 56-57
Author(s):  
S Kumar ◽  
R Baidya ◽  
P Baral
Keyword(s):  
Congenital Anomalies ◽  
Elbow Joint ◽  
Biceps Brachii ◽  
Biceps Tendon ◽  
Biceps Brachii Muscle ◽  
Rare Anomaly ◽  
Long Head Of Biceps ◽  
Long Head

Introduction: Biceps brachii is a muscle of arm which brings about supination when fore-arm is flexed and flexion of elbow joint. Proximally it is attached with two heads: long and short heads.Case report: The absence of long head of biceps brachii muscle is very rare anomaly. It may be unilateral or bilateral with or without other congenital anomalies. The exact prevalence of this anomaly is unknown. This anomaly has been reported to occur as the result of an insult to the fetus during the sixth or seventh week of gestation, at which time the long head of the biceps tendon is developing. J-GMC-N | Volume 11 | Issue 01 | January-June 2018, Page:56-57

Sarcomere Length During Post-Natal Growth of Mammalian Muscle Fibres

1968 ◽  
Vol 3 (4) ◽  
pp. 539-548
Author(s):  
G. GOLDSPINK
Keyword(s):  
Sarcomere Length ◽  
Biceps Brachii ◽  
Muscle Length ◽  
Muscle Fibres ◽  
Biceps Brachii Muscle ◽  
Newborn Animal ◽  
Maximum Tension ◽  
Mammalian Muscle ◽  
Extended Position ◽  
The Difference

The length of the sarcomeres, the A- and the 1-filaments and their percentage overlap were measured in the fibres of the biceps brachii muscle from mice of different ages. The sarcomere length with the limb in the fully extended position was found to increase from 2.3 µ in the newborn animal to 2.8 µ in the adult. This increase was due to a decrease in the percentage overlap of the filaments and not to any change in the filament lengths. The sarcomeres at the ends of the fibres were found to be shorter than those in the middle of the muscle, at all ages. When the muscles were stretched beyond their resting length, only about the middle 60 % of the sarcomeres in the young muscles increased in length. Length/tension plots were obtained for young and old muscles and the difference in the shape of these plots could be explained as being due to the non-functional terminal sarcomeres of the young muscles. The maximum tension developed by the young muscles was found to be attained at an initial muscle length about 10 % greater than their length at maximum limb extension. The adult muscles developed maximum tension at their length at maximum limb extension.

scholarly journals Range of motion, neuromechanical, and architectural adaptations to plantar flexor stretch training in humans

2014 ◽  
Vol 117 (5) ◽  
pp. 452-462 ◽  
Author(s):  
A. J. Blazevich ◽  
D. Cannavan ◽  
C. M. Waugh ◽  
S. C. Miller ◽  
J. B. Thorlund ◽  
...  
Keyword(s):  
Range Of Motion ◽  
Muscle Activation ◽  
Joint Angle ◽  
Maximum Voluntary Contraction ◽  
Muscle Length ◽  
Joint Moment ◽  
Muscle Stiffness ◽  
Control Group ◽  
Plantar Flexor ◽  
Passive Joint

The neuromuscular adaptations in response to muscle stretch training have not been clearly described. In the present study, changes in muscle (at fascicular and whole muscle levels) and tendon mechanics, muscle activity, and spinal motoneuron excitability were examined during standardized plantar flexor stretches after 3 wk of twice daily stretch training (4 × 30 s). No changes were observed in a nonexercising control group ( n = 9), however stretch training elicited a 19.9% increase in dorsiflexion range of motion (ROM) and a 28% increase in passive joint moment at end ROM ( n = 12). Only a trend toward a decrease in passive plantar flexor moment during stretch (−9.9%; P = 0.15) was observed, and no changes in electromyographic amplitudes during ROM or at end ROM were detected. Decreases in Hmax:Mmax(tibial nerve stimulation) were observed at plantar flexed (gastrocnemius medialis and soleus) and neutral (soleus only) joint angles, but not with the ankle dorsiflexed. Muscle and fascicle strain increased (12 vs. 23%) along with a decrease in muscle stiffness (−18%) during stretch to a constant target joint angle. Muscle length at end ROM increased (13%) without a change in fascicle length, fascicle rotation, tendon elongation, or tendon stiffness following training. A lack of change in maximum voluntary contraction moment and rate of force development at any joint angle was taken to indicate a lack of change in series compliance of the muscle-tendon unit. Thus, increases in end ROM were underpinned by increases in maximum tolerable passive joint moment (stretch tolerance) and both muscle and fascicle elongation rather than changes in volitional muscle activation or motoneuron pool excitability.

scholarly journals Experimental study on the sEMG of "joint angle effect" of human muscle strength—Taking biceps brachii as an example

2020 ◽  
Vol 145 ◽  
pp. 01021
Author(s):  
Jianxin Gao ◽  
Cheng Han ◽  
Wenying Huang ◽  
Jianjun Gao ◽  
Liaoliang Nie
Keyword(s):  
Surface Electromyography ◽  
Elbow Joint ◽  
High Speed ◽  
Joint Angle ◽  
Biceps Brachii ◽  
Contraction Force ◽  
High Definition ◽  
Whole Process ◽  
Angle Measuring ◽  
Angle Effect

In the experiment, the author used wave plus wireless surface electromyography system (SEMs + 3-axis acceleration sensor) made in Italy and wave wireless EMG software system, high-definition high-speed camera and human joint angle measuring instrument. Taking human biceps brachii as an example, the static and dynamic isometric contraction of biceps brachii was completed surface electromyography. In the experiment, the surface electromyography of biceps brachii was measured at 30°, 60°, 90°, 120°, 150°, 180° and the surface electromyography of biceps brachii was measured at the same time when the biceps brachii was not loaded or when the biceps brachii was loaded. Secondly, the surface electromyography of biceps brachii was measured at the same time when the biceps brachii completed the whole process of flexion and extension of the elbow (centripetal and centrifugal). Finally, the paper combined with HD The effect of joint angle on the contraction of biceps brachii muscle was analyzed by camera technique. The results show that the static contraction force of biceps brachii is different when the elbow joint is at different angles; in addition, when the dynamic contraction, the contraction force of biceps brachii is inversely proportional to the angle of elbow joint.

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