Biceps Brachii Muscle Length Affects Force Steadiness with and Without Fatigue

2021 ◽  
Author(s):  
Joshua C. Carr ◽  
Xin Ye ◽  
Hayden M. Tharp
Keyword(s):  
Biceps Brachii ◽  
Muscle Length ◽  
Biceps Brachii Muscle ◽  
Force Steadiness

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.

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.

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 Is it the coracobrachialis superior muscle, or is it an unidentified rare variant of coracobrachialis muscle?

2021 ◽  
Author(s):  
Łukasz Olewnik ◽  
Nicol Zielinska ◽  
Łukasz Gołek ◽  
Paloma Aragonés ◽  
Jose Ramon Sanudo
Keyword(s):  
Case Report ◽  
Rare Variant ◽  
Shoulder Joint ◽  
Biceps Brachii ◽  
Coracoid Process ◽  
Biceps Brachii Muscle ◽  
Shoulder Region

AbstractThe coracobrachialis muscle (CBM) originates from the apex of the coracoid process, in common with the short head of the biceps brachii muscle, and from the intermuscular septum. The CBM demonstrates variability in both the proximal and distal attachment, with some extremely rare varieties, such as the coracobrachialis superior, coracobrachialis longus and coracocapsularis muscle. This case report describes an extremely rare variant of the coracobrachialis superior muscle, or a very rare variant of the CBM. Our findings highlight the importance of muscle variants in the shoulder region, especially the coracoid region, and are significant for radiologists, anatomists, physiotherapists and surgeons specializing in the shoulder joint.

scholarly journals Older Adults Exhibit a Reduced Ability to Fully Activate Their Biceps Brachii Muscle

1999 ◽  
Vol 54 (5) ◽  
pp. M249-M253 ◽  
Author(s):  
G. H. Yue ◽  
V. K. Ranganathan ◽  
V. Siemionow ◽  
J. Z. Liu ◽  
V. Sahgal
Keyword(s):  
Older Adults ◽  
Biceps Brachii ◽  
Biceps Brachii Muscle

Biceps Rupture in Water-related Sporting Activities

2010 ◽  
Vol 2 (2) ◽  
pp. 127-130
Author(s):  
Cheng H. Lo ◽  
Christopher Coombs ◽  
Simon N. Bell
Keyword(s):  
Biceps Brachii ◽  
Early Recognition ◽  
Biceps Brachii Muscle ◽  
Muscle Repair ◽  
Biceps Muscle ◽  
Muscle Belly ◽  
Injury Management ◽  
Muscle Rupture ◽  
Biceps Rupture ◽  
Sporting Activities

Closed traumatic disruptions of biceps brachii muscle belly are rarely seen. In this paper, we report two rare cases of biceps brachii muscle belly rupture sustained while water-skiing or wakeboarding and discuss the mechanism of injury, management and outcomes after a literature review. A review of published articles revealed only three previously reported cases of water skiing related biceps muscle rupture. It is important to be vigilant of these injuries, given that early recognition and operative intervention with or without direct muscle repair may optimise outcomes.

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