Article
Anatomic distribution of the axillary nerve and its implications in the treatment of the paralytic shoulder
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Published: | February 6, 2020 |
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Objectives/Interrogation: To evaluate the anatomic distribution of the main and terminal branches of the axillary nerve into the deltoid muscle through dissection and measurement in adult cadavers and to find the best donor for nerve transfer surgery based upon its distribution.
Methods: Anatomic study was performed on 20 shoulders of unembalmed cadavers. The relationships between the nerve and the tip of the acromion, coracoid process, greater tubercle of the humerus, subscapularis muscle, the quadrangular space and all of the nerve branches inside the deltoid muscle were measured regardless of the specimens age and gender. The anatomic branch pattern was also described on each specimen.
Results and Conclusions: The mean distance between the tip of the acromion and the axillary nerve was 6.1 cm (range, 4.6, 7.7 cm). The mean distance between the coracoid process and the axillary nerve was 4.8 cm (range, 4.0, 6.3 cm). The mean distance between the greater tubercle of the humerus and the axillary nerve was 5.2 cm (range, 4.0, 5.8 cm). The axillary nerve gave off no branches before entering into the quadrangular space in all of the specimens. The axillary nerve branched out at a distance of 1.4 cm (range, 0.8-2.4 cm) from the quadrangular space. The anterior branch of the axillary nerve supplied the anterior and middle parts of the deltoid muscle and the posterior branch supplied the posterior part of the deltoid muscle in 80% of the specimens (Type D pattern of distribution, Leechavengvongs et al). These findings regarding the innervation pattern show an important variation in the Colombian population. Our study suggests that nerve transfer to the anterior branch alone would not reinnervate the posterior part of the deltoid muscle in almost all the patients.