Detailed neurovascular anatomy of the serratus anterior muscle: implications for a functional muscle flap with multiple independent force vectors

A functional muscle free flap with multiple muscle segments that could be oriented independently to produce different force vectors would be beneficial in facial reanimation and upper extremity reconstruction. The serratus anterior muscle has this potential because two or more individual muscle slips can be transferred on a single vascular pedicle. Although serratus anterior muscular anatomy has been studied previously, little attention has been given to the intramuscular anatomy. Muscle slips 5 through 9 (and 10, if present) in 50 specimens from 27 cadavers were studied following intraarterial latex injection. Eight specimens were injected with a radiopaque material (latex/diatrizoate/lead mixture) for x-ray delineation of the intramuscular vascular pattern. Slips 5 through 9 are consistently supplied by a single dominant branch of the thoracodorsal artery and innervated by the long thoracic nerve. Dissection revealed that the long thoracic nerve and its branches invariably follow the artery and divide proximal to the corresponding arterial division. There is a consistent vascular pattern to each muscle slip, in which the serratus artery gives rise to common slip arteries, each of which supplies adjacent muscle slips. The mean length of a muscle slip from its origin on the rib periosteum to the division of the common slip artery is 9.6 cm. These findings imply that the slips may be separated to the level of these common slip arteries, with up to five slips transferred on a single neurovascular pedicle and each slip oriented independently to provide multiple muscle force vectors. With these possibilities, the reconstructive surgeon may be able to restore more natural facial animation and better intrinsic muscle function in the upper extremity.     

Neurovascular musculus obliquus internus abdominis flap free transfer for facial reanimation in a single stage

A study of the anatomy and transplantation of the musculus obliquus internus abdominis with a neurovascular pedicle transfer for facial reanimation in one stage is presented. Eleven adult cadavers (22 face sides) were dissected to observe the shape, thickness, innervation, and blood supply of the musculus obliquus internus abdominis. The blood supply of this muscle primarily comes from the musculus obliquus internus abdominis branch of the deep circumflex iliac artery (diameter, 1.3 +/- 0.2 mm), but it can also come from the eleventh intercostal artery (diameter, 1.14 +/- 0.3 mm) and the infracostal artery (diameter, 1.5 +/- 0.2 mm). The branch of the deep circumflex iliac artery and its vena comitans, or the infracostal artery and its vena comitans, could be anastomosed for muscle transplantation. The innervation of the musculus obliquus internus abdominis comes from the tenth and eleventh intercostal nerves (length, 12.7 +/- 1.5 cm) and the infracostal nerve (length, 12.9 +/- 1.3 cm). The eleventh intercostal nerve and the infracostal nerve were selected for anastomosis of muscle transplantation. From November of 1995 to November of 1999, 14 patients with long established facial paralysis were treated with transplantation of a musculus obliquus internus abdominis flap in one stage and were followed for 10 months to 6 years. In 13 patients, the dynamic functions of the transplanted muscles were restored, the obliqueness of the mouth and philtrum while static was corrected, and the facial muscle activities while smiling were harmonized. The eyelids of the paralyzed side could be closed postoperatively, indicating that the function of the orbicularis oculi of the paralyzed side was restored. The single-stage transplantation of a free musculus obliquus internus abdominis flap with one vascular, multi-nerve pedicle is a new method for facial reanimation in the treatment of long established facial paralysis. Because of the simplicity of the procedure and the completeness of the functional reanimation of the paralyzed facial muscles, compared with the results of other free muscle flap transfers, it is an ideal procedure for facial reanimation.     

Temporoparietal fascia: an anatomic and histologic reinvestigation with new potential clinical applications

Temporoparietal fascia constitutes a very important structural unit from both an aesthetic and a reconstructive surgical point of view. A histologically supported anatomic study was conducted for the reappraisal of the anatomic relationships and clinical application potentials of the data obtained. Anatomy of the temporoparietal fascia was investigated on 20 sides from 10 cadavers. After dissections, necropsies were obtained to demonstrate histologic features of the temporoparietal fascia. The outer part of the temporoparietal fascia is continuous with the superficial musculoaponeurotic system (SMAS) in the inferior border and with orbicularis oculi and frontalis muscles in the anterior border. Therefore, plication of the temporoparietal fascia can increase tightness of the SMAS, orbicularis oculi, and frontalis muscle in rhytidectomy. The frontal branches of facial nerve were noted to course parallel to the frontal branch of the superficial temporal artery, lying deeper to the temporoparietal fascia within the innominate fascia. In the view of these findings, conventional subfascial dissection, which is performed to protect frontal branches of the facial nerve, is not reasonable during the temporal part of rhytidectomy. Careful subcutaneous dissection just under the hair follicles is more appropriate to avoid nerve injury and also provides excellent exposure of the temporoparietal fascia for plication in rhytidectomy with protection of the auriculotemporal nerve and the superficial temporal vessels. Furthermore, two layered structures of the temporoparietal fascia are very suitable to insert a framework into the temporoparietal fascia for ear reconstruction to eliminate some of the shortcomings of Brent's technique. A thin muscle layer was also noted within the outer part of the temporoparietal fascia below the temporal line; the term "temporoparietal myofascial flap" would, therefore, be more accurate than "temporoparietal fascial flap." Finally, the innominate fascia and the deep temporal fascia can be elevated with the two layers of the temporoparietal myofascial flap to obtain a well-vascularized, four-layered myofascial flap based on the superficial temporal vessels. This multilayered flap can be used to reconstruct all defects when fine, pliable, thin, multilayered flaps are required.     

The arteria radialis superficialis. An unusual variation of the arteria radialis of man and its phylogenetic significance

During the clinical investigation of 570 soldiers of the German army, we were not able to feel the pulse in 5 cases at the typical place of the radial pulse in the distal part of the forearm. In these 5 cases we were able to find a subcutaneous artery which coursed superficial to the anatomical snuffbox and crossed superficial to the tendon of the extensor pollicis longus muscle. This superficial radial artery enters the deep aspect of the palm between the first and the second metacarpale bones. In three cases we found a bilateral occurrence of this artery, the other variations were observed unilaterally, two on the right side and one on the left side of the forearm. In the family of two patients other members were found who had the same variation of the radial artery. In one of the cases an arteriography of the vessels was made to find the exact anatomical course of the observed variation. We compared our results with the literature on this variation of the radial artery and found agreement on the following course for this vessel. The radial artery divides in the distal fourth of the forearm (5-7 cm proximal to the wrist joint) into two branches. The dorsal branch courses subcutaneously over the tendon of the brachioradialis muscle and runs over the tendon of the extensor pollicis longus muscle to enter the deep aspect of the palm in the first metacarpal space. This dorsal branch courses parallel to the superficial branch of the radial nerve. The palmar branch can be regarded as the 'normal' radial artery, which continues along the medial border of the brachioradialis muscle and courses deep under the tendons of the dorsal muscles of the thumb. The rare appearance (frequency approximately 1%) of a superficial radial artery in man has probably some phylogenetic importance. This is proven by studies on the comparative anatomy of mammals. This variation of the radial artery seems to be homologous to the superficial radial artery which is described in many lower mammals. In human embryos a superficial radial artery is found as well which courses parallel to the superficial branch of the radial nerve and ends on the dorsal side of the hand. Taking all the anatomical and embryological facts into consideration we propose to name this variation of the radial artery the 'arteria radialis superficialis'.     

The thoracoacromial vessels as recipient vessels in microsurgery and supermicrosurgery: an anatomical and sonographic study

The purpose of this study was to investigate the presence and the precise course of the pectoral branch of the thoracoacromial vessels on the underside of the pectoralis major muscle by anatomical dissection and by color Doppler ultrasound. A further goal was to determine whether these vessels were suitable as recipient vessels in microsurgery and supermicrosurgery for breast reconstruction. In 18 cadavers, the pectoral branch of the thoracoacromial vessels was followed caudally until the diameter of the artery diminished to 1 mm. The same examination was carried out in 40 young female volunteers by tracing the vessel course with color Doppler ultrasound. The 1-mm cutoff point of the artery was measured with reference to the manubrium, the midsternal line, the clavicle, and the upper border of the closest rib. In addition, in the cadavers, the 2-mm cutoff point was determined. At both cutoff points, the diameter of the accompanying vein was measured. The pectoral branch of the thoracoacromial vessels with the artery and concomitant veins could be detected on all 100 undersides of the pectoralis major muscle, anatomically and sonographically. In their course from the acromial region downward, the arteries reached a diameter of 1 mm at an average of 9.9 cm from the manubrium, horizontally 9.4 cm from the midsternal line, and vertically 4.0 cm from the lower border of the clavicle. The 1-mm reference point was situated on the upper border of the third rib in 85 percent of cases. The average distance between the 1-mm and the 2-mm cutoff points was 3.5 cm. At the 1-mm cutoff point, the diameter of the vein was 0.9 mm, and at the 2-mm cutoff point, it was 1.7 mm. Because of their central position at the anterior hemithorax, these vessels are easily accessible from mastectomy incisions, even in skin-sparing mastectomies; the donor-site morbidity is negligible; and as the diameters of the vessels gradually decrease along their caudal course, the recipient site can be chosen precisely according to the length and the diameter of the donor vessels and major mismatch can be avoided. Thus, the pectoral branches of the thoracoacromial vessels are well suited as recipient vessels for (super)microsurgery and are a very promising addendum to the thoracodorsal and internal mammary vessels.     

The blood supply of the reverse temporalis muscle flap: anatomic study and clinical implications

Although the reverse temporalis muscle flap has been used clinically, the exact vascular connection between the superficial and deep temporal vessels has not been clearly defined. The purpose of this study was to investigate the vascular territory of the reverse temporalis muscle supplied by the superficial temporal vessels. Six cadaver heads were studied using a colored lead oxide injection through the superficial temporal artery. The specimens were examined macroscopically and radiographically. The reverse temporalis muscle flap was then applied to a clinical case presenting with traumatic anterior skull base defect communicating with the nasal cavity. The cadaver specimens demonstrated that the superficial temporal artery formed an average 1.3 +/- 0.2 cm in width of dense vascular zone, which was located within 1.8 cm below the superior temporal line. The dense vascular network further perfused the anterior and posterior deep temporal arteries and the muscular branch of the middle temporal artery to supply the temporalis muscle. The mean perfused area of the temporalis muscle was 83 percent, ranging from 79 to 89 percent, in five cadaver heads. One cadaver revealed only 55 percent of perfused area in the absence of the muscular branch of the middle temporal artery. The consistent area without perfusion was located in the distal third of the posterior portion of the reverse temporalis muscle. In clinical cases, the reverse temporalis muscle flap was used successfully to obliterate the anterior skull base defect without evidence of muscle flap necrosis. The exact blood supply to the distal third of the posterior portion of the reverse temporalis muscle flap needs to be investigated further in vivo. Particular attention was paid to the inclusion of the muscular branch of the middle temporal artery in this flap to augment the blood supply to the temporalis muscle.     

The long head of the triceps brachii as a free functioning muscle transfer

This anatomic study investigates the possibility of using the long head of the triceps brachii muscle as a free functioning muscle transfer for the upper limb. It has been reported that the long head is not difficult to harvest and that its loss does not create significant donor-site morbidity. The muscle was studied in 23 fresh frozen upper limbs. The long head in all 23 specimens had a constant and proximal vascular pedicle from the profunda brachii artery and vein. The mean pedicle was long (4 cm) and had large-caliber vessels (diameter, 3-mm artery and 4-mm vein). Angiograms were carried out in five specimens and dye perfusion studies in six specimens. A single branch from the radial nerve of at least 7 cm in length innervated the muscle. Muscle architecture was studied in 12 specimens and revealed that the long head of the triceps is better suited for forearm reconstruction than either the gracilis or the latissimus dorsi muscles. The mean physiologic cross-sectional area (8.36 cm(2)) and fiber length (10.8 cm on the superficial surface and 8.2 cm on the deep surface) of the long head match more closely those of the flexor digitorum profundus and the extensor digitorum communis, the muscles most commonly replaced.     

Passive shortening of canine parasternal intercostals during breathing

We have previously demonstrated that the shortening of the canine parasternal intercostals during inspiration results primarily from the muscles' own activation (J. Appl. Physiol. 64: 1546-1553, 1988). In the present studies, we have tested the hypothesis that other inspiratory rib cage muscles may contribute to the parasternal inspiratory shortening. Eight supine, spontaneously breathing dogs were studied. Changes in length of the third or fourth right parasternal intercostal were measured during quiet breathing and during single-breath airway occlusion first with the animal intact, then after selective denervation of the muscle, and finally after bilateral phrenicotomy. Denervating the parasternal virtually eliminated the muscle shortening during quiet inspiration and caused the muscle to lengthen during occluded breaths. After phrenicotomy, however, the parasternal, while being denervated, shortened again a significant amount during both quiet inspiration and occluded breaths. These data thus confirm that a component of the parasternal inspiratory shortening is not active and results from the action of other inspiratory rib cage muscles. Additional studies in four animals demonstrated that the scalene and serratus muscles do not play any role in this phenomenon; it must therefore result from the action of intrinsic rib cage muscles.     

Distribution of the superficial temporal artery in the Chinese adult.

The superficial temporal artery is important in head and neck surgery. Ethnologic variation may affect surgical procedure. In this study, we evaluated the variations of the artery in Chinese adults. We measured its bifurcating location, the diameter of its vessels, and its relationship to nearby structures. A total of 26 cadavers with 52 superficial temporal arteries were examined in 3 consecutive years. The superficial temporal artery ran 1.14 cm anteriorly to the bony external auditory canal. The average diameters of the superficial temporal artery, frontal branch, and parietal branch were 2.14, 1.61, and 1.68 mm, respectively. In 45 of 52 cases (86.5 percent), bifurcation of the artery occurred well above the zygomatic arch. The present study thus demonstrated that the superficial temporal artery in the Chinese adult differs from that in the Caucasian and has provided a detailed anatomic distribution analysis of the superficial temporal artery in Chinese adults, which should benefit the clinician in dealing with operation procedures related to this artery.     

Superficial circumflex iliac artery perforator flap for reconstruction of limb defects

The superficial circumflex iliac artery perforator (SCIP) flap differs from the established groin flap in that it is nourished by only a perforator of the superficial circumflex iliac system and has a short segment (3 to 4 cm in length) of this vascular system. Three cases in which free superficial circumflex iliac artery perforator flaps were successfully transferred for coverage of soft-tissue defects in the limb are described in this article. The advantages of this flap are as follows: no need for deeper and longer dissection for the pedicle vessel, a shorter flap elevation time, possible thinning of the flap with primary defatting, the possibility of an adiposal flap with customized thickness for tissue augmentation, a concealed donor site, minimal donor-site morbidity, and the availability of a large cutaneous vein as a venous drainage system. The disadvantages are the need for dissection for a smaller perforator and an anastomosing technique for small-caliber vessels of less than 1.0 mm.     

New observations on the splenius capitis and rectus capitis ventralis muscles of the Common Swift Apus apus (Apodidae)

In swifts and hummingbirds (Apodiformes), the splenius capitis muscle displays a characteristic modification, the 'cruciform origin'. The muscle pairs arise from the second vertebra by several slips which criss-cross and interdigitate with each other, before inserting into the skull. In the course of a study on the neck muscles of the Common Swift, we paid special attention to the arrangement of these slips of the splenius capitis muscle, and noted a previously unrecognized individual modification of this muscle. In addition, we observed an incipient cruciform origin of the deep portion (slip) of the rectus capitis ventralis muscle that has not been noticed for swifts or any other avian taxon before. The development and function of these modifications of the splenius capitis and rectus capitis ventralis muscle are discussed.     

Transblepharoplasty endoscopic subperiosteal midface lift

The use of endoscopy in the transblepharoplasty midface lift is essential for preventing the complications of facial nerve injury and bleeding. Complete observation allows precise dissection and release of all structures in the composite flap. This technique fully preserves the zygo-orbicular nerve plexus and prevents denervation of the orbicularis oculi and zygomaticus muscles. Blind dissection has a significant probability of denervation of the entire zygo-orbital muscle complex, and avulsion of the zygomaticofacial vessels, with associated postoperative bleeding complications. The modification involving suturing of the "vest" of the combined lateral orbital periosteal and superficial layers of the deep temporal fascia over the elevated "pants" of the orbicularis periosteal flap provides very secure fixation for suspension of the lower eyelid and midface. The use of slowly absorbable polydioxanone sutures for this technique prevents the problems caused by permanent sutures beneath the very thin skin of the lateral canthal area. Careful trimming of the prominent roll of the orbicularis muscle that often develops with suspension eliminates the uneven contour and yields a smooth lower lid appearance. The details and modifications described should decrease the complications and morbidity that can occur with this procedure and provide for a more precise and reliable procedure for rejuvenation of the lower eyelid and midface.     

Ultrasound assessment of the anatomical validity of T3 and L4 as sEMG recording sites

The accuracy of surface EMG measurement is dependent upon minimizing potential crosstalk from other muscles. Although they are deeply situated, in places the erector spinae are covered with electrically silent aponeuroses rather than active muscle tissue. Theoretically these aponeuroses can serve as windows for sEMG recordings. A recent anatomical study concluded that T3 and L4 are ideal sites for recording the ES because the superficial muscle aponeuroses are wide at these sites. The aim of this prospective study was to investigate these sites in vivo using real time ultrasound. Ultrasound images from 20 subjects (10<30 years and 10>70 years; equal numbers of males and females in each group) were acquired during rest and in prone extension with the arms in three different positions. The most superficial aponeurosis widths were measured. The mean T3 aponeurosis width reduced significantly in extension from 4.4±4.7mm at rest to 1.8±2.6mm in extension (p<0.0001). Males had significantly smaller T3 aponeurosis widths than females (p=0.049). The mean L4 aponeurosis width also significantly decreased in extension from 35.5±7.0mm at rest to 29.9±7.2mm in extension (p<0.0001) due to 'doming' of the aponeurosis. Our results demonstrate that T3 is not a reliable site over which to record the ES because the aponeurosis width is too narrow. L4 is a good site if the electrodes are placed no more than 20mm from the midline.     

刺猬的皮肌及其神经支配

刺猬的皮肤,包括皮肤肌和皮下脂肪,是一个质量很大的器官,平均占体重43形,最多可达57％以上。刺猬的皮肌,如果不是动物界中最发达的,也是非常发达的,尤其环状皮肌带约占体重11％(赵以炳等1958)。在功能上,刺猬的皮肌是重要的生理性体温调节器官,背面带针刺的部分有保温御寒作用,腹部有散热机能(赵以炳等1950a)。清醒的刺猬当遇到强敌或其它干扰时,常蜷缩成带剌的球。不活动的冬眠刺猬也取同样姿势,以防侵害。可以说,蜷缩是一种主动的保护性行为,这种强烈的蜷缩主要是由于环状皮肌带持续有力的收缩。尤其令人惊奇的是冬眠时的蜷缩,这是在一般生理活动明显降低的     

The bipedicled osteocutaneous scapula flap: a new subscapular system free flap

Thirty-six adult dissections (14 cadaver and 22 operative) demonstrate the constant presence of the angular branch of the thoracodorsal artery as a vascular pedicle to the inferior pole of the scapula. This vessel originated in all cases just proximal or distal to the serratus branch of the thoracodorsal artery and arborized to the periosteum 6 to 9 cm from the bony branch of the circumflex scapular artery. In eight patients, scapular osteocutaneous flaps were raised preserving the angular branch and the circumflex scapular artery and dissecting up to the subscapular vessels. In all cases, bone was independently perfused by the angular branch. In all six cases where the angular branch was the sole supply to bone, technetium-99m scans demonstrated perfusion. Addition of this vascular pedicle to scapula bone allows two separate bone flaps with one microanastomosis and provides a longer arc of rotation between skin supplied by the circumflex scapular artery and bone. Donor-site morbidity was no greater than with the standard scapula flap.     

The reaction strategy of lower extremity muscles when slips occur to individuals with trans-femoral amputation.

The aim of this study is to investigate the surface electromyography (sEMG) responses of lower extremity muscles for both healthy people and individuals with trans-femoral amputation (TFA), when slip events occur during level walking. Six male individuals with unilateral TFA and five healthy subjects participated in this study. Each subject was required to walk at a self-selected comfortable pace along a 5m plastic walkway, and to perform walking trials on dry and oily conditions respectively. The sEMG signals of muscles on legs and around waist were recorded in each trial and the normalized instantaneous muscle power (IMP) values were employed to quantify the response intensity. The IMP profiles of each muscle in oily-surface walking trials were compared quantitatively with that in dry-surface trials. There are three main findings in this study. (1) Different muscle reaction strategies are employed in slip events by the healthy persons and the individuals with TFA, respectively. Moreover, when the slip event occurs on the prosthetic leg and the intact leg of the individuals with TFA respectively, the muscle reaction strategies are also different. (2) The individuals with TFA face higher risks of fall than the healthy persons no mater slips occur on the prosthetic side or the intact side. (3) The hip muscles, especially the gluteus maximus (GMA) muscles, always enormously contribute to posture adjustment and balance recovery in slip events.     

Surgical anatomy and blood supply of the fascial layers of the temporal region

In 15 fresh cadavers (30 sides), we studied the two layers of fascia in the temporal region, with particular regard to their blood supply and to their usefulness--together or separately--as microvascular free-tissue autografts. The superficial temporal fascia (temporoparietal fascia, epicranial aponeurosis) lies immediately deep to the hair follicles. It is part of the subcutaneous musculoaponeurotic system and is continuous in all directions with other structures belonging to that layer--including the galea above and the SMAS layer of the face below. The deep temporal fascia (temporalis fascia, investing fascia of temporalis) is separated from the superficial fascia by an avascular plane of loose areolar tissue. It completely invests the superficial aspect of the temporalis muscle down to (but not beyond) the zygomatic arch. It is firmly attached to periosteum all around the margin of the muscles. Below it is attached to the upper border of the zygomatic arch. We found the deep temporal fascia to be supplied solely by the middle temporal artery, a constant branch of the superficial temporal. The middle temporal artery arises 1 to 3 cm below the upper border of the zygomatic arch, runs always superficial to the arch, and enters the deep temporal fascia immediately above that layer's attachment to the zygomatic arch. If the middle temporal vessels are protected, the two layers of temporal fascia can be raised together as a fully vascularized tissue island. This island can be fashioned as a bilobed or a double-layered flap, depending on the manner of dissection. The potential surgical usefulness of these findings is discussed.     

Laryngeal nerves, branches in the interior of the larynx

The recurrent laryngeal nerve divides in the most cases outside of the larynx into 2 twigs. The thicker ventral branch has a posterior and an anterior twig. From the posterior one, we counted 6.22 (1 to 12) branches to the posterior cricoarytenoid muscle and 1.48 (1 to 3) to the arytenoid muscle. From the anterior branch 3.54 (1 to 6) twigs run to the lateral cricoarytenoid muscle and 2.06 (1 to 5) to the thyreo-arytenoid muscle. An Ansa GALENI was found in 66%. Its diameter was cranial greater than caudal, its length was measured with 73.6 (56 to 96) mm. A single anastomose was found in 54%, and in 12% numerous variations. We found 8.5 (3 to 13) thicker twigs, which divided themselves in 17 thinner twigs. To the mucous membrane we found 78.5% and to muscles 21.5%. In cases without anastomoses, 3.5 (2 to 5) twigs were running to muscles and 13.4 (1 to 25) to the mucous membrane. The diameter and length of the twigs and their course to muscles and mucous membrane have been estimated. The results are discussed with those of earlier authors.     

Reconstruction of soft-tissue defects using serratus anterior adipofascial free flap

The serratus anterior muscle has been suggested as a versatile and reliable flap for reconstruction of head and neck and extremity injuries. The adipofascial layer overlying the serratus anterior muscle is the anatomic layer, which is supplied by the same branch of thoracodorsal artery. Even though great progress has occurred in the prevention of postoperative adhesion of extremity injuries, the problem has not been completely solved and is still of special importance in complex injuries. Between March of 1995 and February of 1996, seven patients underwent reconstructive operation as a result of soft-tissue defects of the upper or lower extremities or the scalp. We transferred free adipofascial tissue overlying the serratus anterior muscle in three patients and both serratus anterior muscle and adipofascial tissue in four patients. A free adipofascial flap overlying serratus anterior muscle was transferred when a gliding surface was required, owing to the exposure of tendons and neurovascular structures. The average duration from operation to follow-up examination was 8 months (from 4 to 16 months). The results of the operations were satisfactory in functional and cosmetic aspects. This kind of flap was very effective in reconstruction of soft-tissue defects and gliding surfaces for these reasons: easy dissection, the capability of obtaining a long vascular pedicle, large-sized flap, composite flap including muscle or rib, and the fact that there was no serious functional or cosmetic deficit at the donor site.     

Normalization procedures using maximum voluntary isometric contractions for the serratus anterior and trapezius muscles during surface EMG analysis.

The serratus anterior and trapezius muscles are considered to be the only upward rotators of the scapula and are very important for normal shoulder function. A variety of methods have been used to produce a maximum voluntary isometric contraction (MVIC) of these muscles for normalization of EMG data. The purpose of this study was to quantify the surface EMG activity of the serratus anterior muscle and the upper, middle, and lower parts of the trapezius during 9 manual muscle tests performed with maximum effort in 30 subjects. It was found that no one muscle test produced a MVIC for all individuals. Therefore, to perform normalization within each subject, it is suggested that the 2 or 3 tests identified in this study that produce high levels of EMG activity for each muscle be performed. The scapular protraction muscle test that is often used to normalize data for the serratus anterior muscle produced relatively low levels of EMG activity and was not found to be an optimal test. Muscle tests in which an attempt was made to de-rotate the scapula from an upwardly rotated position produced much higher levels of EMG activity in the serratus anterior muscle.