Long Head Of Triceps Brachii Research Articles

Effects of postmortem aging and USDA quality grade on Warner-Bratzler shear force values of seventeen individual beef muscles1

Forty USDA Select and 40 upper two-thirds USDA Choice beef carcasses were used to determine the effects of postmortem aging on tenderness of 17 individual beef muscles. Biceps femoris-long head, complexus, gluteus medius, infraspinatus, longissimus dorsi, psoas major, rectus femoris, semimembranosus, semitendinosus, serratus ventralis, spinalis dorsi, supraspinatus, tensor fasciae latae, teres major, triceps brachii-long head, vastus lateralis, and vastus medialis muscles were removed from each carcass. Seven steaks (2.54-cm thick) were cut from every muscle, and each steak was assigned to one of the following postmortem aging periods: 2, 4, 6, 10, 14, 21, or 28 d postmortem. After completion of the designated aging period, steaks were removed from storage (2 degrees C, never frozen), cooked to a peak internal temperature of 71 degrees C, and evaluated using Warner-Bratzler shear force (WBSF). Analysis of WBSF revealed a 3-way interaction (P = 0.004) among individual muscle, USDA quality grade, and postmortem aging period. With the exception of the Select teres major, WBSF of all muscles (both quality grades) decreased with increasing time of postmortem storage. Nonlinear regression was used to characterize the extent (aging response) and rate of decrease in WBSF from 2 through 28 d postmortem for each muscle within each quality grade. In general, WBSF of upper two-thirds Choice muscles decreased more rapidly from 2 to 10 d postmortem than did corresponding Select muscles. Muscles that had greater aging responses generally had greater 2-d WBSF values. The upper two-thirds Choice psoas major, serratus ventralis, and vastus lateralis muscles required similar aging times to complete a majority of the aging response (< or =0.1 kg of aging response remaining) compared with analogous Select muscles. The upper two-thirds Choice complexus, gluteus medius, semitendinosus, triceps brachii-long head, and vastus medialis muscles required 4 to 6 d less time to complete a majority of the aging response than did comparable Select muscles. Aging times for Select biceps femoris-long head, infraspinatus, longissimus dorsi, rectus femoris, semimembranosus, spinalis dorsi, supraspinatus, and tensor fasciae latae muscles were > or =7 d longer than those for corresponding upper two-thirds Choice muscles. Results from this study suggest that muscle-to-muscle tenderness differences depend on quality grade and aging time and that postmortem aging should be managed with respect to individual muscle and USDA quality grade.

Flavor relationships among muscles from the beef chuck and round1

This research compared off-flavor notes and the relationship of pH and heme-iron content to off-flavor for different beef muscles. After grading, knuckles and shoulder clods were removed from 16 USDA Choice and 14 USDA Select beef carcasses, vacuum-packaged, and aged for 7 d. The rectus femoris (REC), vastus medalis (VAM), vastus lateralis (VAL), teres major (TER), infraspinatus (INF), and triceps brachii-long head (TRI) were separated, cut into steaks, and frozen (-16 degrees C). Sensory analysis was conducted using a trained taste panel, with steaks grilled to an internal temperature of 65 degrees C. Heme-iron concentration and pH were determined. The INF had lower (P < 0.05) off-flavor intensity ratings and less frequent sour flavor than the other muscles, and the VAL had the most intense (P < 0.05) off-flavor ratings and among the greatest frequency of sour, charred, and oxidized flavors. The frequencies of liver-like, bloody, and rancid flavors were not affected by muscle type. Heme-iron concentration did not differ among muscles. Three USDA Select carcasses had intense off-flavor in the muscles. Liver-like flavor was highly negatively correlated with off-flavor intensity for each of the muscles tested. Muscles rated a 5 or below (on an 8-point rating scale, where 1 = extremely intense off-flavor and 8 = no off-flavor) in off-flavor intensity and identified as liver-like by 30% or more of the panelists were grouped together and compared to normal muscles. Those in the liver-flavored group were less frequently identified as charred, probably because the liver-like flavor was so intense. There were no differences between the 2 groups for sour, metallic, bloody, oxidized, or fatty off-flavor notes. Regression equations containing the linear and quadratic functions of heme-iron concentration, muscle pH, and their interaction were established for the frequency of off-flavor notes within each muscle. The REC, TER, VAL, and VAM showed a relationship between pH, heme iron, and off-flavor intensity (P < 0.05). Liver-like flavor was explained partially by pH and heme iron in the REC, VAM, and VAL (R2 = 0.45 to 0.55; P < 0.05). Few other significant relationships were found. Heme iron and pH were unrelated to metallic, oxidized, or rancid flavors for any of the muscles tested. These data suggest that liver-like off-flavors are specific to individual animals, and that pH and heme iron are not strongly related to off-flavor notes.

Muscle Architectural Characteristics in Young and Elderly Men and Women

The purpose of this study was to compare the muscle architectural characteristics, i. e., muscle thickness, pennation angle, fascicle length, of four different groups comprising a total of 121 men and 190 women, divided according to sex and age (i. e., 20 - 39 yrs and 60 - 85 yrs). Muscle thickness and pennation angles of the vastus lateralis (VL), medial gastrocnemius (MG), long head of triceps brachii (TB) muscles were measured by B-mode ultrasonography, and fascicle length was estimated. Men had significantly greater relative muscle thickness (to limb length) than women, but not for MG. Relative muscle thickness of VL was significantly greater in younger subjects than in elderly (men; p < 0.001, women; p < 0.001), although there were no significant differences in relative muscle thickness of MG and TB between younger and elderly subjects. Men had significantly greater pennation angles than women, but not for MG in elderly subjects. The pennation angle of VL was significantly greater in younger subjects than in elderly (men; p < 0.001, women; p < 0.001), although there were no significant differences in pennation angles of MG and TB between younger and elderly subjects. Women had longer relative fascicle lengths (to limb length) of VL than men (p = 0.048 for younger, p = 0.028 for elderly). These results suggest that the decrease of thickness of the vastus lateralis muscle with aging is significant, and that there is the gender difference in the fascicle length of the vastus lateralis muscle.

Effect of task difficulty on muscle activation patterns during rapid single-joint movements.

This study investigated the effect of spatial accuracy demands on movement organization by analyzing the amplitude of the agonist and antagonist muscle activities emerging during horizontal elbow-flexion movements toward spatial targets of varying difficulties. 8 subjects performed elbow-flexion movements toward targets of 3 sizes, located at 2 distances, as rapidly and accurately as possible. For each movement, the elbow angles and the activities of biceps brachii, brachioradialis, and lateral and long heads of triceps brachii were measured. Analysis on the kinematic variables indicated that final elbow angle and peak velocity decreased with increasing index of difficulty of the task in both movement-amplitude conditions. However, movement time increased with increasing index of difficulty. The amplitude of agonist and antagonist muscle activities measured for 100 msec. before movement initiation was also shown to decrease with increasing index of difficulty. Agonist and antagonist muscle activities measured during acceleration phase displayed similar patterns with those of premovement. These results suggest that the task difficulty affects movement organization, and the control system decreases the amplitude of agonist and antagonist muscle activities with an increase in the index of difficulty to enhance the controllability of the limb.

The isometric functional capacity of muscles that cross the elbow

We hypothesized that muscles crossing the elbow have fundamental differences in their capacity for excursion, force generation, and moment generation due to differences in their architecture, moment arm, and the combination of their architecture and moment arm. Muscle fascicle length, sarcomere length, pennation angle, mass, and tendon displacement with elbow flexion were measured for the major elbow muscles in 10 upper extremity specimens. Optimal fascicle length, physiological cross-sectional area (PCSA), moment arm, operating range on the force–length curve, and moment-generating capacity were estimated from these data. Brachioradialis and pronator teres had the longest (17.7 cm) and shortest (5.5 cm) fascicles, respectively. Triceps brachii (combined heads) and brachioradialis had the greatest (14.9 cm 2) and smallest (1.2 cm 2) PCSAs, respectively. Despite a comparable fascicle length, long head of biceps brachii operates over a broader range of the force–length curve (length change=56% of optimal length, 12.8 cm) than the long head of triceps brachii (length change=28% of optimal length, 12.7 cm) because of its larger moment arm (4.7 cm vs. 2.3 cm). Although brachioradialis has a small PCSA, it has a relatively large moment-generating capacity (6.8 cm 3) due to its large moment arm (average peak=7.7 cm). These results emphasize the need to consider the interplay of architecture and moment arm when evaluating the functional capabilities of a muscle.

Topographic Position of Forelimb Motoneuron Pools Is Conserved in Vertebrate Evolution

The neuromotor conservatism hypothesis predicts that neuromotor patterns in homologous tetrapod muscles are conserved evolutionarily despite the musculoskeletal modifications of vertebrate limbs. A complete description of the anatomical organization of the neurons innervating homologous limb muscles is a prerequisite to any test of the neuromotor conservatism hypothesis. This study uses the retrograde neuronal tracer WGA-HRP to selectively label the motor neuron pools of seven homologous forelimb muscles in mice (Mus musculus) and iguanas (Iguana iguana): Mm. pectoralis, spinodeltoideus, biceps brachii, lateral and long heads of triceps brachii, and the supraspinatus and infraspinatus (in mice) or their reptilian homolog, the supracoracoideus (in iguanas). In vertebrates, motoneurons are arranged in longitudinal columns of cells in the ventral horn of the spinal cord. Mouse motor pools average 1,952 μm in length, except the pectoralis pool which averaged 2,949 μm in length. Iguana pools average 3,196 μm in length. The number of neurons per pool ranged from 70–199 in mice and from 58–114 neurons in iguanas. In both iguanas and mice the motor pools for the spinodeltoids, biceps, and the supracoracoideus (or its mammalian homologs) lie anterior to the pectoralis and triceps motor pools. In the transverse plane, the pectoralis pool lies medial to those of the triceps. The pools of the biceps and spinodeltoids are located dorsal and lateral to those of the pectoralis and supracoracoideus (or its homologs in mammals). The resulting motor pool maps support the hypothesis that the anatomical organization of motoneurons in ancestral reptiles has been retained in these two tetrapod descendents.

Force-Velocity Characteristics of Individual Human Skeletal Muscles: TBCIat and TBCIong. Outline of the Method

The aim of the work is to outline a procedure of finding force-velocity (F–V) characteristics (F = f(V)) of individual skeletal muscles of the human locomotor system. The presentation is based on an example concerning extensors of the elbow joint: the lateral and long heads of triceps brachii (TBCIat and TBCIong). The experimental part of the procedure involves a natural movement of using the upper extremity to push an external object of variable, adjustable load, engaging both the elbow and shoulder joint.Five men aged 23 took part in the experiment. Their task was to push the handle of a physical pendulum whose moment of inertia could be adjusted within the range of 58 kg m2-450 kg m2, so as to give it maximum angular velocity. During each trial the movement of the trunk, of the upper extremity and of the pendulum was video recorded and the force applied with the hand to the handle of the pendulum was measured.In order to find the F–V characteristics a simulation model SHOULDER was used, which is capable of solving the synergy problem for muscles of the arm and the shoulder girdle.It was found that despite considerable dispersion of experimental points the respective regression lines revealed a clear tendency of decreasing muscle force for increased shortening velocity of the monoarticular head (TBCIat) and of increasing muscle force for increased lengthening velocity of the biarticular head (TBCIong) of the triceps brachii muscle.

Influence of endurance exercise training on distribution of vascular adaptations in rat skeletal muscle

We hypothesized that an exercise training program consisting of treadmill running at 32 m/min up a 15% incline, 90 min/day, 5 days/wk for 12-14 wk, would elicit vascular adaptation in skeletal muscle of all fiber types in rats. This hypothesis was based on previous reports that this intensity and duration of training caused increases in oxidative capacity in rat skeletal muscle of all fiber types. Skeletal muscle vascular transport capacity was examined with measurements of total and regional (radiolabeled microspheres) flow capacity, capillary filtration coefficient (CFC), and permeability-surface area product (PS) for 51Cr-EDTA in maximally vasodilated (papaverine) hindquarters of control (C; n = 25) and exercise-trained (ET; n = 26) rats. CFC was increased in ET (0.038 +/- 0.001 vs. 0.030 +/- 0.001 ml.min-1 x mmHg-1 x 100 g-1; P < or = 0.001). PS was greater in ET than C (7.80 +/- 0.33 vs. 6.39 +/- 0.37 ml.min-1 x 100 g-1; P < or = 0.01). Citrate synthase activity was increased in the soleus (25%; P < or = 0.05), the medial head (35%; P < or = 0.05), and the red portion of the long head (45%; P < or = 0.005) but not in the white portion of the long head of triceps brachii (P = 0.14) of ET rats. Pressure-flow relationships indicate that total flow was greater (P < or = 0.05) in ET hindquarters at all perfusion pressures. Regional flow data revealed that increases in flow capacity were not evident in muscles composed of all fiber types as predicted.(ABSTRACT TRUNCATED AT 250 WORDS)

A biomechanical analysis of the sticking region in the bench press

The performance of ten elite powerlifters were analyzed in a simulated competition environment using three-dimensional cinematography and surface electromyography while bench pressing approximately 80% of maximum, a maximal load, and an unsuccessful supramaximal attempt. The resultant moment arm (from the sagittal and transverse planes) of the weight about the shoulder axis decreased throughout the upward movement of the bar. The resultant moment arm of the weight about the elbow axis decreased throughout the initial portion of the ascent of the bar, recording a minimum value during the sticking region, and subsequently increased throughout the remainder of the ascent of the bar. The electromyograms produced by the prime mover muscles (sternal portion of pectoralis major, anterior deltoid, long head of triceps brachii) achieved maximal activation at the commencement of the ascent phase of the lift and maintained this level essentially unchanged throughout the upward movement of the bar. The sticking region, therefore, did not appear to be caused by an increase in the moment arm of the weight about the shoulder or elbow joints or by a minimization of muscular activity during this region. A possible mechanism which envisages the sticking region as a force-reduced transition phase between a strain energy-assisted acceleration phase and a mechanically advantageous maximum strength region is postulated.