Surgical outcomes following nerve transfers in upper brachial plexus injuries

Background:

Brachial plexus injuries represent devastating injuries with a poor prognosis. Neurolysis, nerve repair, nerve grafts, nerve transfer, functioning free-muscle transfer and pedicle muscle transfer are the main surgical procedures for treating these injuries. Among these, nerve transfer or neurotization is mainly indicated in root avulsion injury.

Materials and Methods:

We analysed the results of various neurotization techniques in 20 patients (age group 20-41 years, mean 25.7 years) in terms of denervation time, recovery time and functional results. The inclusion criteria for the study included irreparable injuries to the upper roots of brachial plexus (C5, C6 and C7 roots in various combinations), surgery within 10 months of injury and a minimum follow-up period of 18 months. The average denervation period was 4.2 months. Shoulder functions were restored by transfer of spinal accessory nerve to suprascapular nerve (19 patients), and phrenic nerve to suprascapular nerve (1 patient). In 11 patients, axillary nerve was also neurotized using different donors - radial nerve branch to the long head triceps (7 patients), intercostal nerves (2 patients), and phrenic nerve with nerve graft (2 patients). Elbow flexion was restored by transfer of ulnar nerve motor fascicle to the motor branch of biceps (4 patients), both ulnar and median nerve motor fascicles to the biceps and brachialis motor nerves (10 patients), spinal accessory nerve to musculocutaneous nerve with an intervening sural nerve graft (1 patient), intercostal nerves (3rd, 4th and 5th) to musculocutaneous nerve (4 patients) and phrenic nerve to musculocutaneous nerve with an intervening graft (1 patient).

Results:

Motor and sensory recovery was assessed according to Medical Research Council (MRC) Scoring system. In shoulder abduction, five patients scored M4 and three patients M3+. Fair results were obtained in remaining 12 patients. The achieved abduction averaged 95 degrees (range, 50 - 170 degrees). Eight patients scored M4 power in elbow flexion and assessed as excellent results. Good results (M3+) were obtained in seven patients. Five patients had fair results (M2+ to M3).     

创伤性全臂丛撕脱伤上肢整体功能重建的临床研究

 目的 观察采用多组神经移位术结合后期手功能重建恢复全臂丛神经撕脱伤患者主动拾物功能的疗效。方法 33例全臂丛神经撕脱伤患者,一期手术均采用多组神经移位术,即副神经移位修复肩胛上神经恢复肩外展,健侧C7神经经椎体前通路移位与患侧下干直接吻合重建屈指、屈腕功能,同时将下干发出的前臂内侧皮神经移位修复肌皮神经恢复屈肘功能,膈神经与下干后股直接吻合同时重建伸肘、伸指功能。术后选择肌力获得有效恢复(肩外展恢复到30°或以上, 伸肘、伸指肌力达到3级或以上,屈肘、屈腕、屈指肌力达到4级或以上)的患者进行二期手功能重建恢复患手的主动抓握功能。主要包括腕关节固定术、拇外展功能重建及掌板紧缩术等。结果 一期神经移位术后平均41±7.7(36~73)个月。10例患者的肌力恢复达到二期手功能重建的条件,其中8例已进行二期手功能重建。6例患者恢复了部分主动拾物功能,1例因爪形指纠正失败,另1例因腕融合术后伸指肌腱粘连致伸指功能丧失。结论 新设计的多组神经移位术可同时恢复全臂丛撕脱伤患者的肩外展、屈肘、屈腕、屈指及伸肘、伸指的有效肌力,在此基础上通过后期手功能重建,可成功重建患侧上肢的部分主动拾物功能。     

Nerve transfers for restoration of upper extremity motor function in a child with upper extremity motor deficits due to transverse myelitis: case report

Transverse myelitis (TM) may result in permanent neurologic dysfunction. Nerve transfers have been developed to restore function after peripheral nerve injury. Here, we present a case report of a child with permanent right upper extremity weakness due to TM that underwent nerve transfers. The following procedures were performed: double fascicle transfer from median nerve and ulnar nerve to the brachialis and biceps branches of the musculocutaneous nerve, spinal accessory to suprascapular nerve, and medial cord to axillary nerve end-to-side neurorraphy. At 22 months, the patient demonstrated excellent recovery of elbow flexion with minimal improvement in shoulder abduction. We propose that the treatment of permanent deficits from TM represents a novel indication for nerve transfers in a subset of patients.     

Nerve transfer to deltoid muscle using the nerve to the long head of the triceps,part II: a report of 7 cases

PURPOSE: This study reports the results of nerve transfer to the deltoid muscle using the nerve to the long head of the triceps. METHODS: Seven patients with an average age of 25 years with loss of shoulder abduction secondary to upper brachial plexus injuries had nerve transfer using the nerve to the long head of the triceps to the anterior branch(es) of the axillary nerve through the posterior approach. The spinal accessory nerve was used simultaneously for nerve transfer to the suprascapular nerve. The follow-up period ranged from 18 to 28 months (average, 20 mo). RESULTS: All patients recovered deltoid power against resistance (M4) at the last follow-up evaluation. Useful functional recovery was achieved in all 7 patients; 5 had excellent recoveries and 2 had good results. The average shoulder abduction was 124 degrees. No notable weakness of elbow extension was observed. CONCLUSIONS: This method is a reliable and effective procedure for deltoid reconstruction in brachial plexus injury (upper-arm type) and should be combined with spinal accessory nerve transfer to the suprascapular nerve to obtain good shoulder abduction.     

Restoration of shoulder function with nerve transfers in traumatic brachial plexus palsy patients

Shoulder stabilization is of utmost importance in upper extremity reanimation following paralysis from devastating injuries. Although secondary procedures such as tendon and muscle transfers have been used, they never achieve a functional recovery comparable to that following successful reinnervation of the supraspinatus, deltoid, teres minor, and infraspinatus muscles. Early restoration of suprascapular and axillary nerve function through timely brachial plexus reconstruction offers a good opportunity to restore shoulder-joint stability, adequate shoulder abduction, and external rotation function. Overall, in our series, 79% of patients achieved good and excellent shoulder abduction (muscle grade, +3 or more), and 55% of patients achieved good or excellent shoulder external rotation after reinnervation of the suprascapular nerve. The best results were seen when direct neurotization of the suprascapular nerve from the distal spinal accessory nerve or neurotization by the C5 root was carried out. Concomitant neurotization of the axillary nerve yields improved outcomes in shoulder abduction and external rotation function.     

Nerve reconstruction: A cohort study of 93 cases of global brachial plexus palsy

Introduction:

Brachial plexus injury leading to flail upper limb is one of the most disabling injuries. Neglect of the injury and delay in surgeries may preclude reinnervation of the paralysed muscles. Currently for such injuries nerve transfers are the preferred procedures. We here present a series of 93 cases of global brachial plexus palsy treated with nerve transfers.

Materials and Methods:

Ninety-three cases of global palsies out of 384 cases of brachial plexus injury operated by the senior surgeon (AB) were selected. Age varied from 4 to 51 years with 63 patients in 20 to 40 age group and all patients having a minimum follow up of at least 1 year post surgery ranging up to 130 months. The delay before surgery ranged from 15 days to 16 months (mean 3.2 months). The aim of the surgery was to restore the elbow flexion, shoulder abduction, triceps function and wrist and finger flexion in that order of priority. The major nerve transfers used were spinal accessory to suprascapular nerve, intercostal to musculocutaneous nerve and pectoral nerves, contralateral C7 to median and radial nerves. Nerve stumps were used whenever available (30 patients).

Results:

Recovery of ≥ grade 3 power was noted in biceps in 73% (68/93) of patients, shoulder abduction in 89% (43/49), pectoralis major in 100% (8/8). Recovery of grade 2 triceps power was seen in 80% (12/16) patients with nerve transfer to radial nerve. Derotation osteotomies of humerus (n=13) and wrist fusion (n=14) were the most common secondary procedures performed to facilitate alignment and movements of the affected limb. Better results were noted in 59 cases where direct nerve transfers were done (without nerve graft).

Conclusion:

Acceptable function (restoration of biceps power ≥3) can be obtained in more than two thirds (73%) of these global brachial plexus injuries by using the principles of early exploration and nerve transfer with rehabilitation.     

Combined nerve transfers for C5 and C6 brachial plexus avulsion injury

PURPOSE: To report the results of combined nerve transfer in C5 and C6 brachial plexus avulsion injury. METHODS: Fifteen patients had nerve transfers: spinal accessory nerve to the suprascapular nerve, a part of the ulnar nerve to the biceps motor branch, and the nerve to the long head of the triceps to the anterior branch of the axillary nerve. Patients were evaluated with regard to elbow flexion, shoulder abduction, and shoulder external rotation. RESULTS: All patients had recovered full elbow flexion: 13 scored M4 and 2 scored M3. Thirteen of the 15 patients obtained good results. The weight the patients could lift ranged from 0 to 7 kg. All patients had recovery of the deltoid function: 13 scored M4 and 2 scored M3. All 15 patients achieved useful functional recovery. Ten patients experienced excellent recoveries and 5 were classified as having good results. The mean shoulder abduction was 115 degrees . Shoulder external rotation strength was scored as M4 in 9 patients, M3 in 4 patients, and M2 in 2 patients. The range of motion of external rotation that was measured from full internal rotation averaged 97 degrees . No clinical donor nerve deficits were observed. CONCLUSIONS: We recommend combined nerve transfers for C5 and C6 avulsion root injuries. These nerve transfers have the advantage of a quick recovery time as a result of the short regeneration distance without nerve graft. TYPE OF STUDY/LEVEL OF EVIDENCE: Therapeutic, Level IV.     

Brachial plexus palsy in adults with radicular lesions, general concepts, diagnostic approach and results

In post-traumatic brachial plexus lesions in adults, early repair will necessitate a variety of nerve grafting and nerve transfer procedures. In complete palsies, a graft is performed from a radicular stump, using intercostal nerve transfers, partial cross C7 transfer, and the distal spinal accessory nerve. This will provide elbow flexion and extension in 75% of cases, and shoulder abduction or rotation in 50% of cases. In the upper type palsies, ulnar-biceps transfer is the standard procedure. Grafting from a ruptured cervical root, when available, is performed to reanimate the shoulder. In C5 C6 and C7 palsies, extension of the wrist and fingers is provided by tendon transfers. In chronic palsies, elbow flexion and extension loss is treated by means of free muscle transfers, (latissimus dorsi or gracilis) combined with nerve transfers (intercostals or spinal accessory). Secondary procedures are routinely necessary following recovery of elbow flexion. For the shoulder-humeral shaft osteotomy or fusion, for the hand-cosmetic fusion of the wrist and distal radio-ulnar joint in the prone position, or palliative treatment in case of partial recovery. For such weak "plexic hands", we have developed a specific hierarchical functional scale, useful for surgical decisions.     

多组神经移位治疗臂丛上、中干根性撕脱伤重建肩外展及屈肘功能

目的 观察联合应用多组神经移位治疗臂丛上、中干根性撕脱伤的临床效果。方法 我科于2012年4月至2014年4月收治臂丛上、中干根性撕脱伤损伤患者16例,采用副神经斜方肌肌支移位修复肩胛上神经、桡神经肱三头肌长头支移位修复腋神经肌支及Oberlin术式,联合修复臂丛上、中干根性撕脱伤,恢复肩外展及屈肘功能。术后随访采用DASH评分表进行手术疗效评估。结果 术后16例患者中14例得到随访。随访24—28个月(平均25个月),患者肩关节外展恢复至75°-90°,恢复时间9-18个月(平均14个月)。屈肘恢复至100°-160°,恢复时间4-7.5个月（平均5.8个月）。DASH评分8-14分,平均14.6分。结论 臂丛上、中干损伤使用多组神经移位联合治疗,可较好恢复肩外展及屈肘功能,尺神经部分束支移位修复肌皮神经肱二头肌支对手内在肌功能无明显影响。     

Nerve Transfers for Traumatic Brachial Plexus Injury: Advantages and Problems

In recent years nerve transfers have been increasingly used to broaden reconstructive options for brachial plexus reconstruction. Nerve transfer is a procedure where an expendable nerve is connected to a more important nerve in order to reinnervate that nerve. This article outlines the experience of the Scottish National Brachial Plexus Injury Service as our use of nerve transfers has increased. Outcomes have improved for reconstruction of the paralysed shoulder using transfer of the accessory nerve to the suprascapular nerve. Medial pectoral to musculocutaneous nerve transfer has proved reliable for restoration of elbow flexion for patients with C5,6 and C5,6,7 injuries. Problems with nerve transfers include morbidity in the donor nerve territory, co-contraction, and pre-existing injury to the donor nerve. There is a balance of risks in these procedures which should be weighed up in individual cases.     

健侧C7 神经根经椎体前移位修复臂丛上干损伤的中期临床随访

目的 观察健侧C7 神经根经椎体前通路移位修复臂丛上干损伤重建肩外展、屈肘功能的中期效果.方法 健侧C7 神经根经椎体前通路移位修复臂丛上干损伤患者15例,男14例,女1例;年龄15～43岁,平均30岁.全臂丛撕脱伤7例,上、中干撕脱伴下干不全损伤6例,上、中干损伤2例.健侧C7 神经根经椎体前通路移位到患侧臂丛上干的距离平均(7.6±1.7)cm,8例同时行副神经或膈神经移位单独修复肩胛上神经.结果 随访36～63个月,平均50个月.健侧上肢用力内收时,12例患者的肱二头肌、三角肌、胸大肌锁骨部、冈上肌肌力(8例来自副神经或膈神经的支配)均达到4级,大脑皮层运动支配中枢发生临床转化;另3例肌力为3级或以下,尚未发生大脑皮层运动支配中枢的临床转化.健侧上肢用力内收时,8例肩胛上神经单独修复者的肩外展角度平均78.0°,另7例平均43.1..结论 健侧C7 神经根经椎体前通路移位可用于修复臂丛上千损伤,桥接神经的距离短,重建肩外展及屈肘功能的效果良好,大脑皮层运动支配中枢可发生临床转化.     

Nerve repairs for traumatic brachial plexus palsy with root avulsion

Thirty-six patients with traumatic brachial plexus lesions and root avulsions were treated surgically between 1972 and 1986 and were followed for more than 24 months (average, 42.6 months). Neurotization of the musculocutaneous nerve with intercostal nerves or the spinal accessory nerve resulted in satisfactory elbow flexion in 21 of the 33 cases (64%). Combined nerve repairs (i.e., intercostal and spinal accessory neurotization of the terminal branch of the brachial plexus in combination with nerve grafts from the upper spinal nerves of the brachial plexus) created a useful function in at least one functional level of the upper limb for 11 of the 15 cases so treated. Nerve repairs resulted in stability of the shoulder and elbow function controllable with a sensible hand for patients with root avulsion injury of the brachial plexus.     

Combined nerve transfers for repair of the upper brachial plexus injuries through a posterior approach

The upper brachial plexus injury leads to paralysis of muscles innervated by C5 and C6 nerve roots. In this report, we present our experience on the use of the combined nerve transfers for reconstruction of the upper brachial plexus injury. Nine male patients with the upper brachial plexus injury were treated with combined nerve transfers. The time interval between injury and surgery ranged from 3 to 11 months (average, 7 months). The combined nerve transfers include fascicles of the ulnar nerve and/or the median nerve transfer to the biceps and/or the brachialis motor branch, and the spinal accessory nerve (SAN) to the suprascapular nerve (SSN) and triceps branches to the axillary nerve through a posterior approach. At an average of 33 months of follow-up, all patients recovered the full range of the elbow flexion. Six out of nine patients were able to perform the normal range of shoulder abduction with the strength degraded to M3 or M4. These results showed that the technique of the combined nerve transfers, specifically the SAN to the SSN and triceps branches to the axillary nerve through a posterior approach, may be a valuable alternative in the repair of the upper brachial plexus injury. Further evaluations of this technique are necessary.     

联合尺神经束支和臂丛外神经移位治疗臂丛损伤

目的 观察联合尺神经束支和臂丛外神经移位治疗臂丛损伤的临床效果.方法 臂丛损伤6例,其中单纯上干损伤4例;上中干为主,合并下干部分损伤2例.伤后平均2.8个月接受手术.术式包括尺神经部分束支转位至肌皮神经肱二头肌肌支,膈神经或者副神经斜方肌支转位至肩胛上神经,桡神经肱三头肌长头肌支转位修复腋神经肌支.用肱二头肌、岗上肌和三角肌肌力,肩外展和上举角度,尺神经功能损失等指标对手术方式和效果进行评估.结果 6例中5例得到随访,平均随访时间18个月,肱二头肌均在术后3～4个月开始恢复肌力.随访时间18个月以上的4例屈肘M_4~+～M_5;随访时间4个月的1例屈肘M_3~+.其中3例行外展功能重建,单用膈神经修复的病例上臂可上举至180°,外展肌力M_4~+;联合副神经和肱三头肌长头肌支修复的病例上肢可外展90°,肌力M_4~-;单用副神经修复的病例上肢可外展80°,肌力M_3~+.3例手部握持力与术前相同,2例增强.4例手部尺神经供区功能无明显影响,1例小指掌侧皮肤感觉减退,第一骨间背侧肌萎缩.结论 尺神经部分束支转位修复肱二头肌支可以有效的恢复臂丛损伤后屈肘功能;用膈神经修复肩胛上神经可能取得更好的肩外展和上举效果;本组臂丛下干部分损伤的病例受伤均在3个月内,采用此术式同样恢复了肱二头肌功能,未加重原有的手功能障碍.     

Nerve transfer in brachial plexus injuries--comparative analysis of surgical procedures

Nerve transfer is the only possibility for nerve repair in cases of the brachial plexus traction injuries with spinal roots avulsion. From 1980. until 2000. in Institute of Neurosurgery, Clinical Center of Serbia, nerve transfer has been performed in 127(79%) of 159 patients with traction injuries of brachial plexus, i.e., 204 reinnervation procedures has been performed using different donor nerves. We achieved good or satisfactory arm abduction and full range or satisfactory elbow flexion through reinnervation of the axillary and musculocutaneous nerve using different donor nerves in 143 of 204 reinnervations, which presents general rate of useful functional recovery in 70.1% of cases. Mean values of the rate of useful functional recovery in individual modalities of nerve transfer in our series are 50.1% for intercostal and/or spinal accessory nerve transfer, 64.5% for plexo-plexal nerve transfer, 81.7% for regional nerve transfer, and 87.1% for combine nerve transfer.     

多组神经束支部移位治疗臂丛神经上干损伤的近期疗效

目的 通过在各受区神经近入肌点处同时进行多组神经束支部移位,恢复臂丛神经上干损伤后丧失的肩肘功能.方法 2007年2月-9月,收治4例单纯臂丛神经上干损伤男性患者.年龄21～39岁.均为车祸伤.左侧1例,右侧3例.患侧肩关节外展、外旋、上举及屈肘不能;耸肩、伸肘、屈伸腕指肌力≥4级.肌电图检查:副神经、尺神经及肱三头肌长头肌支功能好;正中神经功能轻度受损.患者于伤后3～11个月入院.于全麻下行后路副神经到肩胛上神经、肱三头肌肌支到腋神经、尺神经部分束支到肱二头肌肌支和/或正中神经部分束支到肱肌肌支移位术.结果 术后切口均Ⅰ期愈合,其中1例术后出现手部尺侧麻木症状,经对症处理后症状消失.余患者未出现与供区神经相关的运动、感觉功能受损症状.4例均获随访,随访时间7～12个月.术后3～4个月患侧均出现肩外展、屈肘动作.肌电图显示3组受区肌肉均可记录到新生电位.术后6～7个月,患者肩外展30～65°,屈肘90～120°,肌力3～4级.1例随访12个月患者肩外展、上举、外旋及届肘主动活动度基本正常,三角肌、肱二头肌外形轮廓接近正常.结论 应用功能相近的供体神经进行多组神经束支部移位具有供区损失小、恢复时间快、功能恢复佳等优点.尤其适合因伤后时间长延误治疗及锁骨上探查有风险的臂丛神经上干损伤患者.     

Transfer of the intercostal nerves to the nerve of the long head of the triceps to recover elbow extension in brachial plexus palsy

Restoration of elbow flexion is the first goal in brachial plexus injuries. The current procedures using nerve grafts and nerve transfers authorize more extensive repairs, with different possible targets: shoulder, elbow extension, and hand. Elbow extension is important to stabilize the elbow without the contralateral hand and allows achieving a useful grasp. The transfer of the intercostal nerves to the nerve of the long head of the triceps may restore this function in brachial plexus palsies. Furthermore, in case of C5 to C7 palsy, this transfer spares the radial nerve and gives a chance to spontaneous triceps recovery by the reinnervation from C8 root. Moreover, in case of absence or insufficient (M0 to M2 according to Medical Research Council scoring) recovery of elbow flexion strength by nerve surgery, the reinnervated triceps can be transferred. We present the technique of intercostal nerve transfer to the long head of the triceps branch to restore elbow extension in brachial plexus palsy. Results concerning 10 patients are presented.     

Reconstruction of C5 and C6 brachial plexus avulsion injury by multiple nerve transfers: spinal accessory to suprascapular, ulnar fascicles to biceps branch, and triceps long or lateral head branch to axillary nerve

PURPOSE: In C5 and C6 brachial plexus avulsion lesions, elbow flexion, shoulder abduction, and external rotation are the functions that need to be restored. Because the proximal stumps are not available for grafting, surgical repair is based on nerve transfers. The purpose of this study was to describe and report the results of the use of multiple nerve transfers in the reconstruction of these avulsion injuries. METHODS: Ten patients had multiple nerve transfers: cranial nerve XI to the suprascapular nerve, ulnar nerve fascicles to the biceps motor branch, and triceps long or lateral head motor branch to the axillary nerve. Triceps branch transfer was performed through a posterior arm incision. RESULTS: Two years after surgery, all the patients had recovered full elbow flexion; 7 scored M4 and 3 scored M3+ according to Medical Research Council scoring. All the patients had recovered active abduction and external rotation. Abduction recovery averaged 92 degrees (range, 65 degrees-120 degrees) and external rotation, measured from full internal rotation, averaged 93 degrees (range, 80 degrees-120 degrees). Shoulder abduction strength was graded M4 in 3 patients and M3 in the remaining 7 patients. Shoulder external rotation strength was graded M4 in 2 patients, M3 in 5 patients, and M2 in 3 patients. No donor site deficits were observed. CONCLUSIONS: The proposed nerve transfers constitute a valid strategy in C5-C6 avulsion injury reconstruction.     

Transfer of the accessory nerve to the suprascapular nerve in brachial plexus reconstruction

PURPOSE: Transfer of the accessory nerve to the suprascapular nerve is a common procedure, performed to reestablish shoulder motion in patients with brachial plexus palsy. We propose dissecting both nerves via a distal oblique supraclavicular incision, which can be prolonged up to the scapular notch. The results of the transfer to the suprascapular nerve are compared with those of the combined repair of the suprascapular and axillary nerves. METHODS: Thirty men between the ages of 18 and 37 years with brachial plexus trauma had reparative surgery within 3 to 10 months of their injuries. In partial injuries with a normal triceps, a triceps motor branch transfer to the axillary nerve was performed. The suprascapular and accessory nerves were dissected via an oblique incision, extending from the point at which the plexus crosses the clavicle to the anterior border of the trapezius muscle. In 10 patients with fractures or dislocations of the clavicle, the trapezius muscle was partially elevated to expose the suprascapular nerve at the suprascapular notch. RESULTS: In all cases, transfer of the accessory to the suprascapular nerve was performed without the need for nerve grafts. A double lesion of the suprascapular nerve was identified in 1 patient with clavicular dislocation. In those with total palsy, the average improvement in range of abduction was 45 degrees , but none of the patients with total palsy recovered any active external rotation. Patients with upper-type injury recovered an average of 105 degrees of abduction and external rotation. If only patients with C5-C6 injuries were considered, the range of abduction and external rotation increased to 122 degrees and 118 degrees , respectively. CONCLUSIONS: Use of the accessory nerve for transfer to the suprascapular nerve ensured adequate return of shoulder function, especially when combined with a triceps motor branch transfer to the axillary nerve. The supraclavicular exposure proposed here for the suprascapular and accessory nerves is advantageous and can be extended easily to explore the suprascapular nerve at the scapular notch.     

Functional Recovery Following an End to Side Neurorrhaphy of the Accessory Nerve to the Suprascapular Nerve: Case Report

The use of end-to-side neurrorhaphy remains a controversial topic in peripheral nerve surgery. The authors report the long-term functional outcome following a modified end-to-side motor reinnervation using the spinal accessory to innervate the suprascapular nerve following a C5 to C6 avulsion injury. Additionally, functional outcomes of an end-to-end neurotization of the triceps branch to the axillary nerve and double fascicular transfer of the ulnar and medial nerve to the biceps and brachialis are presented. Excellent functional recoveries are found in respect to shoulder abduction and flexion and elbow flexion.