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Concept: Axillary nerve

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The deltoid is a fascinating muscle with a significant role in shoulder function. It is comprised of three distinct portions (anterior or clavicular, middle or acromial, and posterior or spinal) and acts mainly as an abductor of the shoulder and stabilizer of the humeral head. Deltoid tears are not infrequently associated with large or massive rotator cuff tears and may further jeopardize shoulder function. A variety of other pathologies may affect the deltoid muscle including enthesitis, calcific tendinitis, myositis, infection, tumors, and chronic avulsion injury. Contracture of the deltoid following repeated intramuscular injections could present with progressive abduction deformity and winging of the scapula. The deltoid muscle and its innervating axillary nerve may be injured during shoulder surgery, which may have disastrous functional consequences. Axillary neuropathies leading to deltoid muscle dysfunction include traumatic injuries, quadrilateral space and Parsonage-Turner syndromes, and cause denervation of the deltoid muscle. Finally, abnormalities of the deltoid may originate from nearby pathologies of subdeltoid bursa, acromion, and distal clavicle.

Concepts: Humerus, Shoulder, Rotator cuff, Deltoid muscle, Axillary nerve, Clavicle, Scapula, Acromion

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Restoration of stability and movements at the shoulder joint are the 2 most important goals in the management of brachial plexus injuries. The 2 nerves that are preferentially targeted for this purpose are the suprascapular (SSN) and the axillary (AXN) nerves. These nerve transfers have conventionally been performed by the anterior approach, but recently transfers performed by posterior incisions have been gaining popularity, by virtue of being selective and located close to the target muscles. Herein, we describe the technical details of spinal accessory nerve (SAN) to SSN and triceps branch to AXN for upper plexus injuries, both performed by the posterior approach.

Concepts: Cranial nerves, Brachial plexus, Suprascapular nerve, Trapezius muscle, Axillary nerve, Radial nerve, Accessory nerve

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OBJECTIVE To describe the clinical features, diagnostic procedures, management, and outcome of horses with peripheral neuropathy of a forelimb. DESIGN Retrospective case series. ANIMALS 27 horses. PROCEDURES Records from 2000 to 2013 were reviewed to identify horses with peripheral neuropathy of a forelimb. Horses were grouped as having predominant lesions of a suprascapular nerve, axillary nerve, or radial nerve (alone or in association with other brachial plexus nerves) on the basis of physical examination and diagnostic imaging findings. Treatments were primarily conservative. Signalment, history, lameness characteristics, diagnostic imaging features, case management, and outcomes were evaluated. RESULTS Predominant lesions of a suprascapular nerve, axillary nerve, and radial nerve were identified in 11, 2, and 14 horses, respectively. Eight horses with predominant suprascapular nerve injury and 9 with injury to a radial nerve alone or in association with other nerves returned to their previous activity level or intended use after mean recovery periods of 9.3 and 13.3 months, respectively; 2 horses with a predominant axillary nerve injury had this outcome after a mean 3.5-month recovery period. Ultrasonography was useful for evaluation of muscle atrophy and other injuries during the initial examination (in 27 horses) and the rehabilitation period (in 7 horses). CONCLUSIONS AND CLINICAL RELEVANCE Most horses with peripheral neuropathy of a forelimb returned to athletic soundness following an adequate period of rest. Horses with lesions of a radial nerve alone or in association with other nerves typically required longer recovery times than did those with predominant injuries of a suprascapular nerve.

Concepts: Nervous system, Muscle, Brachial plexus, Suprascapular nerve, Axillary nerve, Radial nerve, Nerves of the upper limb, Posterior cord

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Posterior shoulder tightness (PST) and glenohumeral internal rotation deficit (GIRD) are common physical impairments in overhead sports, such as baseball, cricket and tennis. PST is clinically measured by passive shoulder horizontal adduction with scapula stabilized in supine or side lying. GIRD is generally characterised as concurrent deficits of internal rotation (IR) and total arc of motion in dominant side. Although the mechanisms of PST and GIRD are not clear, it is speculated that they derive from tight posterior glenohumeral capsule and posterior muscles, such as posterior deltoid, infraspinatus and teres minor muscles. Some authors suggest that repetitive tensile stress to posterior structures in follow-through phase in throwing movements could lead to inflammation, scar formation and subsequent tightness in posterior tissues, resulting in PST and GIRD. Since both PST and GIRD are thought to reflect tightness of posterior structures in the shoulder, the term PST is occasionally used instead of GIRD in order to describe decreased IR ROM.

Concepts: Randomized controlled trial, Humerus, Shoulder, Rotator cuff, Teres minor muscle, Supraspinatus muscle, Deltoid muscle, Axillary nerve

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Background The lateral branch of the thoracodorsal nerve (LBTN) is used for nerve transfer in facial, musculocutaneous, axillary nerve injuries and for irreparable C5, C6 spinal nerve lesions and accessory nerve defects. For a successful surgical outcome, the nerve to be used in nerve transfer should be of adequate length and thickness for nerve coaptation. Aim Our objective was to evaluate the length of the LBTN that could be obtained as a donor nerve, externally and within the muscle. Method Eight (8) cadavers with intact upper limbs and thorax which could be positioned in the anatomical position were selected for the study. Cadavers with dissected axillae, brachial plexus or upper limbs were excluded. The thoracodorsal neurovascular bundle was dissected and the number of branches of the thoracodorsal nerve was identified along with its lateral branch. The lateral branch was dissected up to the latissimus dorsi muscle and further intramuscularly. All lengths were measured using a vernier caliper. Results The mean length of the LBTN, up to its first intramuscular branch, is 8.14 cm (range 5.99-12.29 cm). Beyond this, the intramuscular nerve branched further and was of very minute diameter. The mean unbranched intramuscular length of the nerve is 3.36 cm (range 1.3-7.71 cm) which is 41.28% of the total length of the LBTN. Conclusion A significant proportion of the LBTN is found within the latissimus dorsi muscle. This length could potentially be used for direct nerve coaptation by intrafascicular dissection.

Concepts: Latissimus dorsi muscle, Brachial plexus, Axillary artery, Thoracodorsal nerve, Dissection, Axillary nerve, Nerves of the upper limb, Posterior cord

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Quadrilateral space syndrome (QSS) is a rare disorder characterized by axillary nerve and posterior humeral circumflex artery (PHCA) compression within the quadrilateral space. Impingement is most frequently due to trauma, fibrous bands, or hypertrophy of one of the muscular borders. Diagnosis can be complicated by the presence of concurrent traumatic injuries, particularly in athletes. Since many other conditions can mimic QSS, it is often a diagnosis of exclusion. Conservative treatment is often first trialed, including physical exercise modification, physical therapy, and therapeutic massage. In patients unrelieved by conservative measures, surgical decompression of the quadrilateral space may be indicated.

Concepts: Muscle, Exercise, Physical therapy, Exercise physiology, Massage, Axillary nerve, Posterior humeral circumflex artery, Quadrangular space

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Treatment of brachial plexus injuries has slowly improved over the last 45 years. Changes in strategy, techniques, microsurgical equipment and technology have expanded the surgical options to reconstruct these life altering, highly complex injuries. The surgical armamentarium includes neurolysis, nerve repair, nerve grafting, nerve transfers, tendon transfer, muscle transfer and other soft tissue and bony procedures. In this article we have selected five surgical procedures (Oberlin’s procedure, Leechavengvongs' procedure, free functional muscle transfer, radial nerve tendon transfers and C5-C6 nerve grafting in obstetrical birth palsy) that have consistently given us good results in our patients who require surgical reconstruction.

Concepts: Brachial plexus, Axillary nerve, Radial nerve, Posterior cord

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Deltoid paralysis following isolated axillary nerve injury can be managed with triceps motor branch transfer or interpositional grafting. No consensus exists on the treatment that results in superior deltoid function. The purpose of this study was to review the authors' experience with axillary nerve injury management and compare functional outcomes following these two treatment options.

Concepts: Deltoid muscle, Axillary nerve, Radial nerve

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Voluntary elbow extension is essential for optimal upper limb positioning required for daily living activities, particularly above-shoulder maneuvers. The authors present a case of traumatic brachial plexus injury in which paralysis of the musculature selectively supplied by the posterior cord was based on magnetic resonance imaging and nerve conduction studies. An attempt at a radial nerve graft at another center was not effective. Ipsilateral hand function improved after multiple local tendon transfers were performed. Restoration of active elbow extension was not possible using the posterior deltoid or the latissimus dorsi because they were denervated by the primary trauma and so the trapezius muscle was used as a donor muscle unit to restore voluntary elbow extension. The patient resumed biking 6 weeks after the transfer procedure. At 2-year follow-up, full active elbow extension was regained, elbow extension power scored 4 of 5, and the patient reported that he could ride his bicycle for 70 miles.

Concepts: Muscle, Nerve, Brachial plexus, Thoracodorsal nerve, Axillary nerve, Clavicle, Radial nerve, Posterior cord

0

The triceps brachii muscle occupies the posterior compartment of the arm in humans and has three heads. The lateral and medial heads originate from the humerus and the long head arises from the infraglenoid tubercle of the scapula. All heads form a common tendon that inserts onto the olecranon and the deep antebrachial fascia on each side of it. Each head receives its own motor branch, which all are thought to originate from the radial nerve. However, several studies reported that the motor branch of the long head of the triceps (LHT) arises from the axillary nerve or the posterior cord. Here, we dissected 27 triceps in 15 cadavers to analyze the innervation of the LHT and found only radial innervation, which contradicts those studies. We examined studies reporting that the motor branch to the LHT in humans does not arise from the radial nerve as well as studies of the triceps in primates. Occasional variations of the innervation of skeletal muscles are normal, but a change of principal motor innervation from radial to axillary nerve has important implications. This is because the axillary nerve is often involved during shoulder injuries. The precise identification of the prevalence of axillary versus radial innervation is therefore clinically relevant for surgery, nerve drafting, and occupational and physical therapy. We conclude that the primary motor branch to the LHT arises from the radial nerve but axillary/posterior cord innervations occur occasionally. We suggest the development of a standard methodology for further studies. Anat Rec, 301:473-483, 2018. © 2018 Wiley Periodicals, Inc.

Concepts: Muscle, Biceps brachii muscle, Triceps brachii muscle, Brachial plexus, Axillary nerve, Radial nerve, Posterior cord, Radial sulcus