The distribution of Golgi tendon organs and muscle spindles in masseter and temporalis muscles of the cat.

Golgi tendon organs and muscle spindles were identified in serial sections of the temporalis and masseter muscles of kitten and cats. In the kitten, the position of each receptor was plotted in three-dimensional reconstitutions of the muscles. Seventy-four spindles and twenty tendon organs were identified in the temporalis, all in the region of the insertion into the mandible. Thirty-four spindles and six organs were located at the origin of the masseter muscle. The receptors were in deep portions of both muscles. All tendon organs were found to form complexes with one or more spindles.     

Topography of corpuscular mechanoreceptors in the shoulder joint region of monodelphis domestica

The topography and structure of corpuscular mechanoreceptors in the shoulder joint capsule and periarticular connective tissue of a small laboratory marsupial (monodelphis domestica) were studied using light and electron microscopy. This animal is known to use its upper extremities for a wide range of activities like climbing and manipulating food. Thus, the shoulder joint of this animal species has a similar wide range of movement as the human shoulder joint, but is small enough for serial sectioning in its entirety. Silver stained serial paraffin sections were examined under the light microscope and the distribution of the different types of mechanoreceptors was reconstructed using three-dimensional image processing. In addition, selected mechanoreceptors were studied electron microscopically. Approximately 100 small lamellated corpuscles were found in the dense connective tissue of the joint capsule close to the insertion on the scapula and in the thickening of the joint capsule close to the glenoid labrum. Ruffini corpuscles were found in much smaller numbers in the moderately dense connective tissue of the axillary region. Only very few Vater-Pacinian corpuscles were seen in the soft periarticular connective tissue. The large number and localization of mechanoreceptor corpuscles in the shoulder joint capsule especially close to the glenoid labrum suggests, that these specialized nerve endings are likely to play an important role in control of joint movement. They can induce protective reflexes during extreme movements in the shoulder joint preventing shoulder luxation by increasing the tone of muscles pressing the humerus head into the glenoid cavity.     

人肌腱袖肌群的构筑学研究

本的目的是了解肌腱袖肌群的构筑特点，功能及其临床意义，对10侧人肌腱袖诸肌进行了构筑学研究，结果表明，冈上肌是环羽肌，其生理横切面积与肌重的比率显大于其余三肌（P＜0．05），作推测冈上肌在人类是一块处于进化状态的上肢带肌，肩胛下肌是由5－7个羽构成的多羽肌，冈下肌与小圆肌为羽肌，以上三肌的生理横切面积之和比冈上肌和三角肌的生理横切面积之和更大，这充分说明人类肩关节运动中协同肌群的重要性，本讨论了肌腿袖肌群的临床意义。     

Distribution of sensory receptors in joints of the upper cervical column in the laboratory marsupial monodelphis domestica.

In order to investigate the sensory innervation, the upper cervical spine of a small laboratory marsupial (monodelphis domestica) was examined with serial section light microscopy and re-embedding of selected sections for electron microscopy. Large numbers of free nerve endings supplied by A delta- and C-fibres were found in the longitudinal ligaments and facet joint capsules. Electron microscopically, areas of direct contact between axon and collagen fibres of the surrounding connective tissue separated only by the basal lamina were observed. Such structural adaptations suggest mechanoreceptive or polymodal nociceptive functions. In addition, about 100 small lamellated corpuscles were found in the longitudinal ligaments mainly concentrated around the first intervertebral disk. Electron microscopy shows finger-like processes extending from the axon terminal into the inner core lamellae. These are the likely sites of the mechanoelectric transduction process. Smaller numbers of lamellated corpuscles were seen in the lower intervertebral disks and facet joint capsules. Lamellated corpuscles are known to function as rapidly adapting mechanoreceptors supplementing information supplied by muscle spindles to the CNS about position and movement of the cervical spine.     

The moment arms of the muscles spanning the glenohumeral joint: a systematic review

The moment arm of a muscle represents its leverage or torque‐producing capacity, and is indicative of the role of the muscle in joint actuation. The objective of this study was to undertake a systematic review of the moment arms of the major muscles spanning the glenohumeral joint during abduction, flexion and axial rotation. Moment arm data for the deltoid, pectoralis major, latissimus dorsi, teres major, supraspinatus, infraspinatus, subscapularis and teres minor were reported when measured using the geometric and tendon excursion methods. The anterior and middle sub‐regions of the deltoid had the largest humeral elevator moment arm values of all muscles during coronal‐ and scapular‐plane abduction, as well as during flexion. The pectoralis major, latissimus dorsi and teres major had the largest depressor moment arms, with each of these muscles exhibiting prominent leverage in shoulder adduction, and the latissimus dorsi and teres major also in extension. The rotator cuff muscles had the largest axial rotation moment arms regardless of the axial position of the humerus. The supraspinatus had the most prominent elevator moment arms during early abduction in both the coronal and scapular planes as well as in flexion. This systematic review shows that the rotator cuff muscles function as humeral rotators and weak humeral depressors or elevators, while the three sub‐regions of the deltoid behave as substantial humeral elevators throughout the range of humeral motion. The pectoralis major, latissimus dorsi and teres major are significant shoulder depressors, particularly during abduction. This study provides muscle moment arm data on functionally relevant shoulder movements that are involved in tasks of daily living, including lifting and pushing. The results may be useful in quantifying shoulder muscle function during specific planes of movement, in designing and validating computational models of the shoulder, and in planning surgical procedures such as tendon transfer surgery.     

Ultrasound Dimensions of the Rotator Cuff and Other Associated Structures in Korean Healthy Adults

In evaluating patients complaining of shoulder pain, ultrasonography is an emerging imaging tool due to convenience, low cost, high sensitivity and specificity. However, normative values of ultrasound dimensions of the shoulder to be compared with pathologic findings in Korean adults are not provided yet. We evaluated the ultrasound dimensions of the rotator cuff, long head of biceps tendon, deltoid muscle and acromioclavicular joint in Korean healthy adults. Shoulder ultrasonography was performed on 200 shoulders from 100 healthy adults. The dimensions of the thickness of rotator cuff (supraspinatus, infraspinatus, subscapularis tendon), deltoid muscle, long head of biceps tendon, subacromial subdeltoid bursa, and acromioclavicular joint interval were measured in a standardized manner. Differences in measurements among sex, age, and dominant arms were compared.The thickness of rotator cuff tendons (supraspinatus, infraspinatus, subscapularis) and deltoid muscle were significantly different between men and women. The thickness of subacromial subdeltoid bursa was significantly different between men and women for non-dominant side. In rotator cuff tendon measurements, the differences between dominant and non-dominant shoulders were not significant, which means the asymptomatic contralateral shoulder can be used to estimate the normal reference values. When stratified by age divided by 10 years, the measurements of supraspinatus, subscapularis and deltoid thickness showed tendency of increase with the age. The acromioclavicular joint interval, on the other hand, revealed decreasing tendency. This report suggests normative values of ultrasound dimensions of healthy Korean population with varying age, and can be useful as reference values in evaluating shoulder pathology, especially in rotator cuff tendon pathology.     

Density of muscle spindles in prosimian shoulder muscles reflects locomotor adaptation

We examined the correlation between the density of muscle spindles in shoulder muscles and the locomotor mode in three species of prosimian primates: the slow loris (Nycticebus coucang), Garnett's galago (Otolemur garnettii), and the ring-tailed lemur (Lemur catta). The shoulder muscles (supraspinatus, infraspinatus, teres major, teres minor, and subscapularis) were embedded in celloidin and cut into transverse serial thin sections (40 microm); then, every tenth section was stained using the Azan staining technique. The relative muscle weights and the density of the muscle spindles were determined. The slow loris muscles were heavier and had sparser muscle spindles, as compared to Garnett's galago. These features suggest that the shoulder muscles of the slow loris are more adapted to generating propulsive force and stabilizing the shoulder joint during locomotion and play a less controlling role in forelimb movements. In contrast, Garnett's galago possessed smaller shoulder muscles with denser spindles that are suitable for the control of more rapid locomotor movements. The mean relative weight and the mean spindle density in the shoulder muscles of the ring-tailed lemur were between those of the other primates, suggesting that the spindle density is not simply a consequence of taxonomic status.     

The incidence and variety of Golgi tendon organs in extraocular muscles of the rhesus monkey

Summary Golgi tendon organs of distal tendons of recrus muscles were traced in serial transverse sections using a light microscope and their identity confirmed with an electron microscope. One or two tendon organs were present in eight of ten muscles taken from four adult rhesus monkeys and none were present in the other two. Tendon organs were unusually small averaging 270 m in length and 36 m in maximum width; three of them were bifid, at one or both ends and the remainder were fusiform. Some lay wholly within tendon without direct attachment of muscle fibres and in the others the tip of a single felderstruktur (slow, non-twitch) muscle fibre entered the tendon organ capsule proximally and occupied the full width.Nerve terminals of most tendon organs compared with those found in other muscles with similar organelles and variety of shape. In three tendon organs with inserted muscle fibres, however, terminals with regular profiles, larger aggregations of clear vesicles and fewer mitochondria were present. The latter type of terminal and the encapsulated felderstruktur muscle fibres are features shared by the large numbers of myotendinous cylinders present in extraocular muscles and it is argued that tendon organs and myotendinous cylinders might be of common origin. If this is the case, then the overwhelming majority of myotendinous cylinders suggests that tendon organs may be an aberrant development in extraocular muscles and of little significance in the total sensory output.     

Rotator cuff muscles perform different functional roles during shoulder external rotation exercises

The aim of this study was to compare activity in shoulder muscles during an external rotation task under conditions of increasing arm support to investigate whether changing support requirements would influence muscle recruitment levels, particularly in the rotator cuff (RC) muscles. Electromyographic recordings were collected from seven shoulder muscles using surface and indwelling electrodes. The dominant shoulder of 14 healthy participants were examined during dynamic shoulder external rotation performed at 90° abduction with the arm fully supported, partially supported, and unsupported. Linear regressions between arm support load and the averaged muscle activity across participants for each muscle showed infraspinatus predominantly contributing to rotating the shoulder whilst supraspinatus, deltoid, upper trapezius, and serratus anterior were predominantly functioning in support/stabilization roles. During dynamic shoulder external rotation in mid‐range abduction, the RC muscles perform different functional roles. Infraspinatus is responsible for producing external rotation torque, supraspinatus is playing a larger joint stabilizer role, and subscapularis is contributing minimally to joint stability. The results also indicate that increasing support load requirements during an external rotation task may be a functionally specific way to retrain the stabilization function of axioscapular muscles. Manipulating joint stabilization requirements while maintaining constant rotational load is a novel method of investigating the differential contribution of muscles to joint movement and stabilization during a given task. Clin. Anat. 2013. © 2012 Wiley Periodicals, Inc.     

Lines of action and stabilizing potential of the shoulder musculature

The objective of the present study was to measure the lines of action of 18 major muscles and muscle sub‐regions crossing the glenohumeral joint of the human shoulder, and to compute the potential contribution of these muscles to joint shear and compression during scapular‐plane abduction and sagittal‐plane flexion. The stabilizing potential of a muscle was found by assessing its contribution to superior/inferior and anterior/posterior joint shear in the scapular and transverse planes, respectively. A muscle with stabilizing potential was oriented to apply more compression than shear at the glenohumeral joint, whereas a muscle with destabilizing potential was oriented to apply more shear. Significant differences in lines of action and stabilizing capacities were measured across sub‐regions of the deltoid and rotator cuff in both planes of elevation (P < 0.05), and substantial differences were observed in the pectoralis major and latissimus dorsi. The results showed that, during abduction and flexion, the rotator cuff muscle sub‐regions were more favourably aligned to stabilize the glenohumeral joint in the transverse plane than in the scapular plane and that, overall, the anterior supraspinatus was most favourably oriented to apply glenohumeral joint compression. The superior pectoralis major and inferior latissimus dorsi were the chief potential scapular‐plane destabilizers, demonstrating the most significant capacity to impart superior and inferior shear to the glenohumeral joint, respectively. The middle and anterior deltoid were also significant potential contributors to superior shear, opposing the combined destabilizing inferior shear potential of the latissimus dorsi and inferior subscapularis. As potential stabilizers, the posterior deltoid and subscapularis had posteriorly‐directed muscle lines of action, whereas the teres minor and infraspinatus had anteriorly‐directed lines of action. Knowledge of the lines of action and stabilizing potential of individual sub‐regions of the shoulder musculature may assist clinicians in identifying muscle‐related joint instabilities, assist surgeons in planning tendon reconstructive surgery, aid in the development of rehabilitation procedures designed to improve joint stability, and facilitate development and validation of biomechanical computer models of the shoulder complex.     

Alteration of proprioceptive messages induced by tendon vibration in man: a microneurographic study

Summary The activities of single proprioceptive fibres were recorded from the lateral peroneal nerve using transcutaneously implanted tungsten microelectrodes. Unitary discharges originating from muscle spindle primary and secondary endings and Golgi tendon organs were identified by means of various physiological tests. The sensitivity of proprioceptors to mechanical vibrations with a constant low amplitude (0.2–0.5 mm) applied at various frequencies to the tendon of the receptor-bearing muscle was studied. Muscle spindle primary endings (Ia fibres) were found to be the most sensitive to this mechanical stimulus. In some cases their discharge could be driven in a one-to-one manner up to 180 Hz. Most of them also fired harmonically with the vibration up to 80 Hz and then discharged in a subharmonic manner (1/2–1/3) with increasing vibration frequencies. Muscle spindle secondary endings (II fibres) and Golgi tendon organs (Ib fibres) were found to be either insensitive or only slightly sensitive to tendon vibration in relaxed muscles. The effects of tendon vibration on muscle spindle sensory endings response to muscle lengthening and shortening induced by imposed constant velocity or sinusoidal movements of the ankle joint were studied. Modulation of the proprioceptive discharge frequency coding the various joint movement parameters was either completely or partly masked by the receptor response to vibration, depending on the vibration frequency. Moreover, vibrations combined with sinusoidal joint movements elicited quantitatively erroneous proprioceptive messages concerning the movement parameters (amplitude, velocity). The sensitivity of the Golgi tendon organs to vibration increased greatly when the receptor-bearing muscle was tonically contracted. These data confirm that vibration is able to preferentially activate the Ia afferent channel, even when the vibration amplitude is low. They define the frequency sensitivity of the muscle spindle primary and secondary endings and the Golgi tendon organs. They also show that the physiological messages triggered by ongoing motor activities undergo a series of changes during the exposure of muscles to vibration.     

A comprehensive analysis of muscle recruitment patterns during shoulder flexion: an electromyographic study

Although flexion is a common component of the routine clinical assessment of the shoulder the muscle recruitment patterns during this movement are not clearly understood making valid interpretation of potential muscle dysfunction problematic. The purpose of this study was to comprehensively examine shoulder muscle activity during flexion in order to compare the activity levels and recruitment patterns of shoulder flexor, scapular lateral rotator and rotator cuff muscles. Electromyographic (EMG) data were recorded from 12 shoulder muscles sites in 15 volunteers. Flexion was performed in standing in the sagittal plane at no load, 20%, and 60% of each subject's maximum load. EMG data were normalized to maximum values obtained during maximum voluntary contractions. Results indicated that anterior deltoid, pectoralis major, supraspinatus, infraspinatus, serratus anterior, upper, and lower trapezius were activated at similar moderate levels. However, subscapularis was activated at low levels and significantly lower than supraspinatus and infraspinatus. Similar activity patterns across time were demonstrated in the muscles that produce flexion torque, laterally rotate the scapula, as well as supraspinatus and infraspinatus, and did not change as flexion load increased. The onset of activity in supraspinatus and anterior deltoid occurred at the same time and prior to movement of the limb at all loads with infraspinatus activity also occurring prior to movement onset at the medium and high load conditions only. Posterior rotator cuff muscles appear to be counterbalancing anterior translational forces produced during flexion and it would appear that supraspinatus is one of the muscles that consistently "initiates" flexion.     

Physiological properties of muscle spindles in dorsal neck muscles of the cat.

1. Single-fiber recording was used to examine the properties of 107 spindle endings in cat biventer cervicis (BC) and complexus (CM) muscles. Responses of receptors were examined following muscle contraction and ramp and hold stretch. Twenty-two endings in splenius (SP) were also examined, but their responses could not be quantitated because the anatomy of SP prevented the application of appropriate stretches. 2. Conduction velocitites of spindle afferents ranged from 13 to 90 m/s. Endings with primary response patterns usually had faster conduction velocities than secondary endings, but there was overlap in the conduction velocity ranges of the two subgroups. 3. Most neck spindle afferents could be classified as either primary or secondary by a constellation of physiological criteria including dynamic response pattern, dynamic index, and variability of resting discharge frequency. However, 22 of 107 endings from BC and CM had responses with characteristics intermediate between primary and secondary responses. The possible sources of these characteristics are discussed. 4. Despite the similarity in properties between spindles of different neck muscles, the length sensitivities of CM spindles were high compared to those of BC spindles. CM spindles showed length-related modulation of firing frequency over a more restricted range of initial muscle lengths than did BC spindles. 5. Eight Golgi tendon organs (GTO) were identified by their characteristics responses. Conduction velocities obtained for five GTO afferent nerves ranged from 50 to 67 m/s. Recordings were also made from receptros in deep muscles surrounding the vertebrae. These receptors had properties characteristic of muscle spindles.     

EMG of scapulohumeral muscles in the chimpanzee during reaching and “arboreal” locomotion

Current views on the function of the deltoid and rotator cuff muscles emphasize their roles in arm-raising as participants in a scapulohumeral force “couple.” The acceptance of such a mechanism is based primarily on a 1944 EMG study of human shoulder muscle action. More recently, it has been suggested that shoulder joint stabilization constitutes a second and equally important function of the cuff musculature, especially in nonhuman primates which habitually use their forelimbs in overhead postural and locomotor activities. Few comparative data exist, however, on the actual recruitment patterns of these muscles in different species. In order to assess the general applicability of a scapulohumeral force couple model, and the functional significance of the differential development of the scapulohumeral musculature among primate species, we have undertaken a detailed study of shoulder muscle activity patterns in nonhuman primates employing telemetered electromyography, which permits examination of unfettered natural behaviors and locomotion. The results of our research on the chimpanzee, Pan troglodytes, on voluntary reaching and two forms of “arboreal” locomotion reveal four ways in which previous perceptions of the function of the scapulohumeral muscles must be revised: (1) the posterior deltoid is completely different in function from the middle and anterior regions of this muscle; (2) the integrity of the glenohumeral joint during suspensory postures is not maintained solely by osseoligamentous structures; (3) the function of teres minor is entirely different from that of the other rotator cuff muscles and is more similar to the posterior deltoid and teres major; and (4) each remaining member of the rotator cuff plays a distinct, and often unique, role during natural behaviors. These results clearly refute the view that the muscles of the rotator cuff act as a single functional unit in any way, and an alternative to the force couple model is proposed.     

Ultrasonographic findings of the shoulder in patients with rheumatoid arthritis and comparison with physical examination

The objectives of this study were: 1) to identify the ultrasonographic (US) abnormalities and 2) to compare the findings of physical examination with US findings in rheumatoid arthritis (RA) patients with shoulder pain. We studied 30 RA patients. Physical examination was performed systemically as follows: 1) area of tenderness; 2) range of passive and active shoulder motion; 3) impingement tests; 4) maneuvers for determining the location of the tendon lesions. US investigations included the biceps, the supraspinatus, infraspinatus, and subscapularis tendons; the subacromial-subdeltoid bursa; and the glenohumeral and acromioclavicular joints. Thirty RA patients with 35 painful and 25 non-painful shoulders were examined. The range of motion affected the most by shoulder pain was abduction. The most frequent US finding of shoulder joint was effusion in the long head of the biceps tendon. Among the rotator cuff tendons, subscapularis was the most frequently involved. Tendon tear was also common among non-painful shoulders. Physical examination used for the diagnosis of shoulder pain had low sensitivity and specificity for detecting abnormalities in the rheumatoid shoulder joint. In conclusion, US abnormalities showed frequent tendon tears in our RA patients. Physical examination had low sensitivity and specificity for detecting rotator cuff tear in the rheumatoid shoulder joint.     

The afferent innervation of two infrahyoid muscles of the cat

1. The afferent innervation of the straplike muscles of the infrahyoid region were investigated in two ways. The morphology of spindles and counts of tendon organs were investigated by the gold chloride technique in ten muscles. Spindle counts were made in forty pairs of thyrohyoid and infrahyoid muscles. De-efferenting of the nerves to these muscles was done in three cats and the calibre spectra of the afferent innervation investigated. These were compared with the total counts of fibres in intact nerves.2. In the thyrohyoid, spindles are frequently absent. No tendon organs were seen. In the large infrahyoid (combined sternohyoid and sternothyroid), spindle counts varied from 0 to 20 and the mean spindle count per gram of muscle was 3.5. A maximum of five tendon organs were seen in the muscle. Both spindle and tendon organ counts are low when compared with a limb muscle of similar weight and size.3. In the infrahyoid muscle complex spindles were about equal in number to simple spindles.4. Counts of spindles in the infrahyoid muscle in families of three or more siblings suggest that some families of kittens tend to have higher spindle counts than other families.5. The afferent innervation of the two muscles varied between 21 and 42% of the total fibre population and the fibre diameter spectrum is in keeping with the low counts of encapsulated endings.     

本体感觉神经肌肉易化训练对运动性肩袖损伤功能恢复的影响

目的 探讨本体感觉神经肌肉易化(proprioceptive neuromuscular facilitation, PNF)训练对运动性肩袖损伤功能恢复的作用。方法 将46名运动性肩袖损伤大学生按性别分层,并随机分为弹力带抗阻+被动关节活动度(range of motion, ROM)训练组(对照组)与PNF训练组(实验组),采用目测类比评分法(visual analog scale, VAS)对肩关节主观疼痛程度进行评定,检测肩袖损伤各手法试验疼痛阳性率及肩关节肌力、主动ROM,并采用改良UCLA肩关节评分系统对肩关节综合功能进行评定。结果 训练后,两组VAS评分、各手法实验疼痛阳性率均低于训练前水平,其中实验组低于对照组;两组受试者肩关节各方向肌力、各方向主动ROM、改良UCLA肩关节评分等均高于训练前水平,其中实验组内旋肌力、内外旋的主动ROM、改良UCLA肩关节评分高于对照组。结论 PNF康复训练可减轻运动性肩袖损伤的疼痛感,提高关节主动ROM、肌力及UCLA肩关节评分;PNF训练对运动性肩袖损伤功能改善作用要优于弹力带抗阻+被动关节ROM训练。     

A quantitative study of muscle spindles and tendon organs in some intrinsic muscles of the hand in the bonnet monkey (Macaca radiata)

The number and density of muscle spindles and tendon organs have been determined in the following intrinsic muscles of the hand of bonnet monkeys: I lumbrical, II lumbrical, abductor digiti minimi, adductor pollicis, and I dorsal interosseous. All these muscles were found to be very rich in muscle spindles (17.6 to 42.31 per gram wet weight) but relatively poor in tendon organs (0.606 to 10.06 per gram wet weight). The lumbricals have very few tendon organs. The possible functional significance of these findings has been discussed.     

肩袖修补的生物力学研究进展

肩袖是维持肩关节运动与动态稳定的重要结构。肩袖损伤改变了其独特的生物力学作用,导致肩关节疼痛及活动障碍。尽管缝合技术与固定方法不断改进,术后再撕裂率仍然很高。理解正常肩袖的生物力学机制以及恢复损伤后肩袖的特殊生物力学作用,是预防再撕裂的关键。本文对近年来肩袖损伤修补的生物力学相关研究进行综述,以期为临床手术开展提供一定的理论指导。