Long Head Of Triceps Brachii Research Articles

AXILLARY NERVE SUPPLYING MOTOR BRANCH TO LONG HEAD OF TRICEPS BRACHII MUSCLE: A CASE REPORT AND REVIEW OF LITERATURE

All three heads of the triceps brachii are classically described as being innervated by the radial nerve in the textbooks. Some clinical observations of traumatic injuries of the axillary nerve with associated paralysis of the long head of triceps and cadaveric studies have suggested that the axillary nerve may innervate the long head of triceps. During routine dissection to undergraduate M.B.B.S students, we found axillary nerve giving a motor branch to long head of triceps brachii on right side, in an adult male cadaver aged about 60 years. We conducted extensive literature search to analyse the previous studies reporting such variations and the studies conducted on the radial nerve or triceps brachii innervation pattern. This variation is clinically important for surgeons, orthopedicians and anaesthetist while performing surgeries and pain management therapies on the upper limb.

Subject-Specific EMG Modeling with Multiple Muscles: A Preliminary Study.

Modeling of surface electromyographic (EMG) signal has been proven valuable for signal interpretation and algorithm validation. However, most EMG models are currently limited to single muscle, either with numerical or analytical approaches. Here, we present a preliminary study of a subject-specific EMG model with multiple muscles. Magnetic resonance (MR) technique is used to acquire accurate cross section of the upper limb and contours of five muscle heads (biceps brachii, brachialis, lateral head, medial head, and long head of triceps brachii). The MR image is adjusted to an idealized cylindrical volume conductor model by image registration. High-density surface EMG signals are generated for two movements - elbow flexion and elbow extension. The simulated and experimental potentials were compared using activation maps. Similar activation zones were observed for each movement. These preliminary results indicate the feasibility of the multi-muscle model to generate EMG signals for complex movements, thus providing reliable data for algorithm validation.

Specific prime movers’ excitation during free-weight bench press variations and chest press machine in competitive bodybuilders

The current study compared the muscle excitation in free-weight bench press variations and chest press machine. Ten competitive bodybuilders were recruited. The EMG-RMS amplitude of clavicular and sternocostal head of pectoralis major, long head of triceps brachii and anterior and lateral deltoid was recorded while performing horizontal (BP), inclined (45°) (IBP) or declined (−15°) bench press (DBP) and chest press machine (CP). Four non-exhaustive repetitions were performed using 80% of 1-repetition maximum of each exercise. Both concentric and eccentric phases were recorded. During the concentric phase, [d effect size: 2.78/7.80] clavicular head was more excited in IBP and less excited in CP (d: −9.69/−4.39) compared to all other exercises. The sternocostal head was similarly excited in DBP vs. BP and BP vs. CP and more excited (d: 2.42/9.92) compared to IBP. Triceps brachii excitation was overall greater (d: 2.01/6.75) in BP and DBP compared to all other exercises. Anterior deltoid was less excited (d: 3.84/19.77) in DBP compared to all other exercises. Lateral deltoid excitation was greater (d: 0.96/3.10) in BP, IBP and DBP compared to CP. Muscle excitation during the eccentric phase followed a similar pattern, with the exception of the greater (d: 3.89/11.32) excitation in the clavicular head in BP compared to all other exercises. The present outcomes showed that the excitation of the clavicular and sternocostal head of pectoralis major depends on the bench inclination angle. The use of BP variations vs. CP allows overall greater triceps brachii and lateral deltoid excitation, due to the greater instability.

Transfer of the triceps brachii to the finger and thumb extensors: Anatomical study and report on one case

Our aims were to study the anatomical feasibility of triceps brachii long head (TBLH) transfer to the extensor digitorum communis (EDC) and extensor pollicis longus (EPL) tendons through a medial route, and to report on its first clinical application. Dissections were conducted on 10 fresh-frozen cadaver specimens. Using a posteromedial approach, the TBLH was separated from the remaining triceps and extended distally with a fascia lata strip. This strip was then tunneled through a medial route and secured distally to the EDC and EPL tendons. The transfer tenodesis effect during elbow extension was assessed with metacarpophalangeal (MCP) joint motion of the thumb and index finger, and the distance between the thumb and index finger tips (TI distance). This transfer was performed in an eight-year-old boy with incomplete recovery of a right brachial plexus birth palsy; preoperatively, shoulder and elbow functions were recovered as well as active gripping distally, but he had no active wrist or finger extension. With the trapeziometacarpal and radiocarpal joints stabilized, 90° elbow extension provided a mean extension of the thumb and index finger MCP joints of 34 ± 5° and 90 ± 11°, respectively, with a mean TI distance of 116 ± 16 mm. Twelve months after surgery, the boy had full active MCP joint extension, independent from elbow extension. Transferring the TBLH to the EDC and EPL tendons is anatomically feasible. Larger clinical studies will be needed to assess more adequately its functional outcomes.

Effect of exercise order with barbell and machine modalities on upper body volume load and myoelectric activity

ABSTRACT The purpose of this study was to investigate the influence of exercise order on volume load (VL) and myoelectric activation (EMG) during the bench press (BP), military press (MP) and close-grip bench press (CGBP) exercises executed with a barbell and Smith machine. Twelve men experienced in resistance training performed four different exercise sessions in randomised order. Each session consisted of four sets of a given exercise order: O1 = CGBP + MP + BP with barbell; O2 = inverse O1 with barbell, O3 = same O1 with Smith Machine; O4 = same O2 with Smith machine. EMG was assessed for the Clavicular head pectoralis major (PMC), anterior deltoid (AD), triceps brachii long head (TBLH) and biceps brachii (BB). Results showed that VL in BP was affected by exercise order, independent of the mode (p < 0.05). However, the CGBP showed higher VL in O1. Moreover, when the BP was positioned last in the sequence (O1 and O3), myoelectric activity was higher for PMC, AD and TBLH (p < 0.05). Findings were similar in the CGBP (PMC and TBLH), but for the AD (Smith machine > barbell, p < 0.05). Therefore, it appears that the order and modes of exercises influence both volume load and myoelectric activation patterns during multiple set of resistance training.

Surgical treatment of disabling shoulder hypertonia in patients with brain injury

Little is known about shoulder hypertonia in patients with brain injury. The principal aim of our study was to assess the results of spastic shoulder surgery in our team experience. Sixteen patients (18 shoulders) were retrospectively reviewed. The following were studied: etiology of hypertonia, shoulder deformation schemes, initial aims of surgery, shoulder pre- and postoperative mobility, impact of surgery on limb function when possible. None limb was functional preoperatively. Spontaneously, shoulders were all in a medial rotation, in adduction in 15 cases, in abduction in 3 cases. One had spontaneous retroposition. Therapeutic aim was hygienic in all and pain-relief in 6. Ten neurotomies of the lateral pectoral nerve (LPN), 8 intramuscular lengthening of the latissimus dorsi (LD), 9 percutaneous tenotomies of the pectoralis major (PM), one neurotomy of the motor nerve for the long head of triceps brachii (LHTB) and one intramuscular lengthening of the teres major (TM) were performed. Mean age at surgery was 52.1 (24–73). Etiology was vascular in 11, anoxic in 2, one had traumatic brain injury, one multiple sclerosis, one cervicarthrosic myelopathy. Preoperatively, the mean results for passive abduction of the shoulder was 50.6° (10–90) and for the passive lateral rotation was −5° (−70; 20). Postoperatively, there were respectively improved at 87.7° (60–160) and 6.7° (−20; 20). Only 3 muscles presented with residual tightness (two PM and 1TM) in patients where an isolated neurotomy of the lateral pectoral nerve (LPN) had been achieved. All of the initial objectives of the surgery were satisfied. One patient recovered a partial functionnal limb thanks to a recovered active shoulder flexion. In classical medial rotation-adduction deformation schemes, surgery performed on the 3 main involved muscles (PM, LD, TM) offers good results in term of passive mobility of the shoulder and pain-relief.

Anatomic analysis of the whole articular capsule of the shoulder joint, with reference to the capsular attachment and thickness

BackgroundAlthough conventional Bankart repair has been the accepted procedure for traumatic anterior glenohumeral instability, the humeral avulsion of the glenohumeral ligament or an elongation of the capsule remains challenging to decide the appropriate treatment. The anatomical knowledge regarding the whole capsule of glenohumeral joint is necessary to accurately treat for the capsular disorders. The aims of the current study were to investigate the anatomical features of capsular attachment and thickness in a whole capsule of glenohumeral joint.MethodsWe used 13 shoulders in the current study. In 9 shoulders, we macroscopically measured the attachment widths of the capsulolabrum complex on the scapular glenoid, and the attachment widths of the capsule on the humerus in reference to the scapular origin of the long head of triceps brachii, and the humeral insertion of the rotator cuff tendons. We additionally used 4 cadaveric shoulders, which were embalmed using Thiel’s method, for the analysis of the thickness in a whole capsule by using micro-CT.ResultsThe glenoidal attachment of the articular capsule appeared to have a consistent width except for the superior part of the origin of the long head of triceps brachii. On the humerus, the articular capsule was widely attached to areas without overlying rotator cuffs, with the widest width (17.3 ± 0.9 mm) attached to the axillary pouch. The inferior part of the capsule, which was consistently thicker than the superior part, continued to the superior part along the glenoid and humeral side edge.ConclusionsThe current study showed that the inferior part of the glenohumeral capsule had a wide humeral attachment from the inferior edge of the subscapularis insertion to the inferior edge of the teres minor insertion via the anatomical neck of the humerus, and the thickness of it was thicker than the superior part of the capsule.

Iliocapsularis and Long Head of Triceps Brachii Innervation: Not Such “Textbook” Cases

Anatomy instructors rely on accurate anatomical texts to facilitate instruction. While the understanding of anatomy continues to evolve, recent advancements are most reliably reflected in the vast amount of peer‐reviewed literature (PRL). Adjustments in anatomy textbooks (TBs), however, may take years to occur due to the publishing constraints such as illustrations and content vetting procedures. Consequently, TBs tend to lag behind the PRL with respect to new content. Subsequently, anatomy instruction may be dated despite the well‐intentioned instructor. Here we highlight two musculoskeletal‐focused discrepancies in anatomical PRL and TB literature: the presence of the Iliocapsularis (IC) and the innervation of the Long Head of Triceps Brachii (LHTB). To explore potential discrepancies, we used convenience sampling and audited 16 widely‐used TBs published within the past 10 years (3.1 ± 2.8 years) to determine the presence of IC and the innervation of the LHTB. We also analyzed PRL published within the past 18 years (5.4 ± 6.7 years) which focused on studies that used MRI or dissection to determine the presence of IC, and dissection only to explore the innervation of LHTB to the triceps. We conducted human dissection to verify the literature audit findings. To better evaluate the presence of IC, we dissected 22 anterior hips on preserved limbs in 11 cadavers and 5 unpreserved limbs in 3 cadavers. To better assess the innervation of the LHTB, we dissected the posterior shoulder and arm on 5 preserved limbs in 5 cadavers and 3 unpreserved limbs in 3 cadavers, with the aim of completing LHTB dissections on a minimum of 20 limbs. Out of 16 TBs reviewed, only 1 suggested the presence of IC and all reported the radial nerve as the innervation of LHTB (Table 1). Conversely, 4 PRL studies used dissection or MRI to assess the presence of IC and 3 studies used dissection to assess the innervation of LHTB by nerves other than the radial nerve (namely the axillary nerve) (Table 2). When pooling the individuals assessed in PRL, 100% were found to have an IC (n=271) and 72.2% were found to have a LHTB innervated by the axillary nerve. Our dissections of the anterior hips revealed that the IC was present in 100% of the 27 limbs. Our dissections of the posterior shoulder and arm revealed that the axillary nerve innervated the LHTB in 50% of the 8 bodies, including 2 of the 5 preserved limbs and 2 of the 3 unpreserved limbs. This study demonstrates that recently published TBs are not in alignment with the anatomical findings of our dissections or, more importantly, with the PRL. These findings suggest that anatomist instructors, as well as clinicians, should be familiar with recently published PRL and not rely solely on anatomical TBs.Support or Funding InformationNoneThis abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Super-selective cervical nerve root stimulation in contralateral C7 transfer: An intraoperative study

ObjectiveWe designed this study using super-selective intraoperative cervical nerve root stimulation aiming to support decision making about complete or partial contralateral C7 (cC7) nerve root transfer in patients with multiple cervical root avulsion injury. MethodsSuper-selective intraoperative stimulations of anterior, lateral, medial and posterior aspect of C5–C8 nerve roots were performed. Compound muscle action potentials (CMAP) were recorded in the lateral part of the deltoid (DM), long head of biceps brachii (BCM), brachioradial (BRM), long head of triceps brachii (TCM), and extensor digitorum communis (EDC) muscle. Muscle strength was documented immediately after cC7 transfer procedures and on scheduled follow-up visits according to the Medical Research Council (MRC) scale. ResultsIn the DM, stimulation of the posterior aspect of C5 resulted in the largest CMAP amplitudes (2.0 mV ± 1.9; 80% ± 28.3). The BCM CMAPs induced by the different aspects of C6 all revealed homogenous stimulation results. Stimulation of the lateral aspect of C7 induced the largest amplitude of TCM CMAPs (1.3 mV ± 1.0; 67.1% ± 43.3). CMAP amplitudes of individual muscles and individual contributions of cervical nerve roots to the TCM varied between subjects. Overall donor side morbidity was low, no permanent motor deficit occurred. ConclusionA super-selective intraoperative cervical nerve root stimulation may help minimize donor side morbidity in transfer procedures. Individual differences of cervical nerve root innervation pattern need to be addressed in future electrophysiological studies. SignificanceOur study outlines individual differences of cervical nerve root innervation pattern.

A validated approach for collecting fine-wire electromyographic recordings in four canine shoulder muscles during highly dynamic tasks

This study investigated the feasibility of obtaining ultrasound-guided intramuscular fine-wire electromyographic (fEMG) recordings from four canine shoulder muscles during highly dynamic activities. Four cadaveric canines were utilised to confirm the appropriate anatomical landmarks and the use of real time ultrasound guidance for electrode placement for four shoulder muscles: Biceps Brachii (BB), Supraspinatus (SP), Infraspinatus (IF), and Triceps Brachii – Long Head (TBLH). Electromyographic activity of the left BB, S P, IF, and TBLH was then recorded in two research dogs while walking and trotting to refine the data collection procedures. Finally, the full experimental protocol was piloted with two client-owned, specially-trained agility dogs, confirming the feasibility of collecting fEMG recordings while performing dynamic, highly-specific agility-related tasks and verifying our EMG amplitude normalisation protocol to enable comparisons across muscles and performance tasks. We present specific guidelines regarding the placement of fEMG electrodes and data collection/normalisation procedures to enable investigations of muscle activation during dynamic activities.

Muscle hardness of the triceps brachii before and after a resistance exercise session: a shear wave ultrasound elastography study.

Muscle hardness indicates muscle condition, and its measurement before and after resistance exercise is essential for preventing resistance training-induced muscle injury. To investigate muscle hardness of the triceps brachii (TB) before and immediately after a resistance exercise session involving the elbow extensors. In 18 young men, muscle hardness of the long head of TB was measured at 50%, 60%, and 70% point along the length of the upper arm from the acromial process of the scapula to the lateral epicondyle of the humerus by using shear wave ultrasound elastography. At the same sites, muscle thickness of the long head of TB was also measured by ultrasonography. Resistance exercise was performed using a dumbbell with a mass adjusted to 80% of the one-repetition maximum. Although the exercise-induced increase in muscle hardness was significant at all the regions, muscle hardness was significantly higher at 70% of the upper arm length than at the other regions before and after resistance exercise. The exercise-induced increase in muscle thickness was also significant, but the relative changes in muscle hardness before and after resistance exercise were not correlated with the corresponding relative changes in muscle thickness at each region. These results indicate the small effect of exercise-induced muscle swelling on exercise-induced changes in muscle hardness. We suggest that muscle damage and/or injury, particularly at the distal region of TB, should be carefully considered to safely perform resistance exercise.

Cadaveric investigation into the innervation of the long head of triceps brachii (726.9)

All three heads of the Triceps brachii are classically described as being innervated by the radial nerve. A previous study of 20 cadaveric shoulders revealed that in 13 specimens the long head of the triceps (LHT) was supplied by a branch of the axillary nerve, not the radial nerve. In our current study 20 cadaveric shoulders were dissected via a combined anterior and extensile dorsal approach. The dissections were photographed and nerve maps were created. Distances from proximal LHT attachment to the point of neuromuscular insertion were measured with calipers. The results indicated that in 60% of the specimens the axillary nerve contributed to the innervation of the LHT; in 15% axillary nerve alone and in 45% combined axillary and radial nerve. These findings have clinical significance in understanding why triceps brachii dysfunction is sometimes associated with axillary nerve injuries.

Unilateral Third Head of Biceps Brachii with Associated Neurovascular Variants in both the Upper Limbs of a Single Cadaver

During routine undergraduate dissection in the upper extremities of a 65 years old male cadaver in the department of Anatomy at Dr. PSIMS &amp; RF, coexistence of muscular and neurovascular variants were identified .Muscular variations included presence of additional head(third) of biceps brachii in the left arm, accompanied with medially positioned median nerve in relation to brachial artery bilaterally . Teres minor muscle was not identified and the origin of long head of triceps brachii extended upto the lateral border of scapula on the left side. Both the medial cutaneous nerves of arm and forearm arouse from a single trunk bilaterally. In the right limb the axillary artery showed only four branches instead of six branches, with common trunk for thoraco-acromial and lateral thoracic artery and common trunk for subscapular and posterior circumflex humeral artery. Knowledge of coexistence of these variations would of profound importance surgically and clinically, especially in limb injuries and surgical repairs. DOI: http://dx.doi.org/10.3126/ajms.v5i1.7391 Asian Journal of Medical Science Vol.5(1) 2014 pp.81-85

Anatomical and clinical substantiation of the long head of triceps transposition to restore active forearm flexion in patients with arthrogryposis

Purpose: to investigate anatomic features of the long head of triceps brachii in relation to its using as a pedicle flap for restoration of active forearm flexion in patients with arthrogryposis. Material and methods. Anatomical studies were performed on 15 fresh frozen human upper limbs from 9 cadavers. Arteries were perfused with radiopaque masses and following preparation, sectional roentgenography, morphometry of anatomical structures were carried. 29 patients with the lack of active elbow flexion aged from 8 months to 15 years were examined (clinical, neurological and physiological studies) and treated in Turner Scientific and Research Institute for Children's Orthopedics from 2008 to 2012. Results and conclusion. Anatomical studies demonstrated the possibility of transposition of the long head of triceps to forearm flexors position. The long head of triceps can be simply separated from the other two heads, it has independent innervation and blood supply, its vascular pedicle is easily identified, and length of extraorgan vessels and nerves is sufficient to transfer the muscle as a pedicle flap. Clinical study has shown the principal possibility and effectiveness of restoration of active forearm flexion in patients with arthrogryposis using the long head of triceps brachii.

Exercise does not increase skeletal muscle FNDC5 protein or mRNA in pigs

Endurance exercise training (EX) is reported to increase FNDC5 expression in skeletal muscle (SkM) of mice (Nature 481:463, 2012). We tested the hypothesis that EX increases FNDC5 expression in pig SkM. Castrated male Rapacz hypercholesterolemic (FH) and normal Yucatan miniature swine (Y) were divided into EX and unexercised (SED) groups. After 16–20 weeks pigs were anesthetized and tissue samples collected and FNDC5 gene expression measured by RT‐PCR. Citrate synthase activity (CS) (index of EX‐induced adaptation) was increased in SkM samples of both FH and Y EX. FNDC5 mRNA appeared 64% less deltoid and 25% less in long head of triceps brachii (LHT) SkM of FH EX pigs. EX did not appear to affect FNDC5 mRNA expression in fat or heart muscle. FNDC5 mRNA expression in subcutaneous fat was comparable to that in the SkM. EX enhanced PGC1α mRNA levels which were much higher in the SkM samples than in fat samples. The changes in PGC1α mRNA levels were not correlated with FNDC5 mRNA. Despite the increase in CS activity in SkM, there was no difference in FNDC5 protein content (Western blot) between SED and EX SkM of Y pigs. We conclude that EX does not increase FNDC5 mRNA or protein in pig SkM.

Function of shoulder muscles of driver in vehicle steering maneuver

In order to study the function of muscles of driver shoulder during vehicle steering, identification of relations between electromyograph (EMG) activity of 10 shoulder muscles and steering force was performed. The procedure was to perform controlled steering maneuver by right hand in a driving simulator, and based on analyzing the EMG data with steering force in the steering wheel plane, the function was identified. It was found that muscle function depends strongly on both steering rotation and steering torque directions. In clockwise steering, the long head of triceps brachii was the prime mover and an important contributor to clockwise moment, while the sternocostal portion of the pectoralis major, the lateral head of triceps brachii, biceps brachii and teres major were the important stabilizers or fixators. In contrast, in counterclockwise steering, the anterior, middle and posterior deltoid, the clavicular portion of the pectoralis major and infraspinatus were the prime movers and also the important contributors to counterclockwise moment, while the sternocostal portion of the pectoralis major, the lateral head of triceps brachii, biceps brachii and teres major were the important stabilizers or fixators. We conclude that the prime movers are primarily a consequence of steering direction, while the stabilizers or fixators are primarily constant. These results can be used to improve the neuromuscular model and estimate the steering comfort of driver. electromyograph, muscle function, steering maneuver

Chemical composition and cooking properties of beef forequarter muscles of Mexican cattle from different genotypes

Beef forequarter muscles biceps brachii (BRB), brachialis (BRA), complexus (COM), splenius (SPL), infraspinatus (INF), teres major (TER), rhomboideus (RHO), subscapularis (SUB), supraspinatus (SUP), triceps brachii long-head (TRB) and triceps brachii lateral-head (TRI) were obtained from Mexican beef carcasses originated from Bos indicus (Bi, n=10) or Bos taurus (Bt, n=10) young bulls. Muscles were analyzed for WBSF, cooking loss, and moisture and fat contents. INF had the lowest WBSF (37.23N) and cooking loss (31.78%) of all. RHO exhibited the lowest moisture (72.62%) and highest fat content (5.23%) of all. Bi genotype exhibited higher WBSF (53.78, 48.69N), higher cook loss (36.27, 34.32%), higher fat content (2.93, 2.35%), and lower moisture content (73.70, 75.07%) than Bt. Further research is needed to estimate the actual consumer acceptance of beef forequarter muscles and their marketing potential as individual cuts in the Mexican market.

Electrophysiological study of the dominant motor innervation to the extensor digitorum communis muscle and long head of triceps brachii at posterior divisions of brachial plexus

Restoration of elbow and finger extension function is still challenging in management of complete brachial plexus avulsion injury, mainly because of fewer available donor nerves for transfer to the radial nerve. Selective neurotization could be a potentially alternative for overcoming this dilemma. This study was designed to identify the innervation dominance of the extensor digitorum communis muscle (EDCM) and long head of the triceps brachii (LTB) at the level of division of brachial plexus. From February 2008 to October 2009, 17 patients with complete brachial plexus avulsion injury underwent the procedure of contralateral C7 nerve root transfer. The posterior divisions of brachial plexus on the healthy donor side were intraoperatively stimulated and the compound muscle action potentials (CMAPs) from the extensor digitorum communis muscle and long head of triceps brachii were recorded by an electrophysiological device. In 13 out of 17 patients (76.5%), the maximal amplitude of CMAP from EDCM was induced by stimulation of the posterior division of lower trunk (PDLT). The mean amplitudes of CMAP from EDCM with stimulation of the posterior division of upper trunk (PDUT), middle trunk (PDMT), and PDLT were 0.64 ± 0.95, 1.64 ± 1.56, and 5.32 ± 4.67 mV (P < 0.05), respectively. The maximal amplitude of CMAP from LTB was induced mainly by stimulation of the PDMT) and PDLT (6 out of 11 and 5 out of 11 patients). The mean amplitudes of CMAP from LTB with stimulation of the PDUT, PDMT, and PDLT were 0.15 ± 0.24, 5.20 ± 4.27, and 7.48 ± 9.90 mV, respectively. The differences of CMAPs between stimulation of PDUT and other two divisions were significant (P < 0.05). From the electrophysiological point of view, this study showed that the PDLT was the major motor division innervating EDCM, and the PDMT and PDLT shared the similar proportion of LTB innervation.

Effects of Days on Concentrate Feed and Postmortem Aging on Carcass and Palatability Characteristics of Selected Muscles from Cull Beef Cows

<h2>ABSTRACT</h2> Twenty-four beef cows were selected to examine the effects of concentrate feeding on performance and to examine the effects of concentrate feeding and postmortem aging (10 or 20 d) on the triceps brachii lateral and long heads, infraspinatus, longissimus lumborum, psoas major, gluteus medius, tensor fascia latae, rectus femoris, and vastus lateralis. Cows were randomly assigned to a concentrate diet for 0, 42, or 84 d. Carcass characteristics were measured and Warner-Bratzler shear force, sensory evaluation, and collagen analyses were performed on selected muscles. Cow BW, ADG, and BCS increased (P < 0.02) after 84 d. Hot carcass weight, ribeye area, fat thickness, marbling, and muscling increased (P < 0.02) after 84 d. Soluble collagen content increased (P < 0.01) in the triceps brachii-long head and longissimus lumborum after 84 d. There was a days on concentrate × muscle interaction (P < 0.01) for Warner-Bratzler shear force with the longissimus lumborum and gluteus medius decreasing with increasing days. Sensory evaluation showed that steaks became more tender (P < 0.01) after 84 d and exhibited less (P < 0.01) off-flavor after 42 d. Extended postmortem aging (20 d) decreased (P < 0.01) Warner-Bratzler shear force and increased (P < 0.01) sensory tenderness; however, postmortem aging did not increase (P > 0.05) sensory off-flavor detection. Concentrate feeding of cull cows for 84 d improved carcass characteristics and the tenderness of several muscles. These muscles may be aged for 20 d postmortem to achieve maximal tenderness without detrimental off-flavor production.

Effect of days on concentrate feed on sensory off-flavor score, off-flavor descriptor and fatty acid profiles for selected muscles from cull beef cows

The effects of short-term realimentation (0, 42 or 84 days) of cull beef cows ( n = 24) and post-mortem aging (10 or 20 days) of selected muscles on sensory off-flavor score, off-flavor descriptors of m. Gluteus medius (GLM), m. Longissimus lumborum (LOL), m. Triceps brachii-long head (LON) and m. Rectus femoris (REF) and fatty acid profiles (GLM, LOL and LON) were researched. Post-mortem aging did not affect sensory off-flavor detection or the interaction with muscle or treatment ( P ⩾ 0.65). Sensory off-flavor scores were lower ( P < 0.01) for steaks that were derived from cull cows fed a concentrate diet for at least 42 days. As well, the number of samples that had detectable off-flavors decreased ( P < 0.01) when cull cows were fed for 42 days. Realimentation did have an effect on fatty acid profiles ( P < 0.05). However, regression analysis showed changes in sensory off-flavor score were not influenced ( P > 0.05) by alterations in fatty acid profiles.