title: Intramuscular innervation patterns of the brachialis muscle.
abstract: The aim of this study was to provide accurate anatomical descriptions of the patterns of innervation of the brachialis muscle by the musculocutaneous, radial, and median nerves. Sihler's staining method was applied to 20 brachialis muscles from 10 cadavers to reveal the intramuscular distribution patterns of the musculocutaneous, radial, and median nerves. Three patterns of innervation of the brachialis muscle by the three studied nerves were found: single, double, and triple. These innervation patterns were categorized into four types: Type I--only the musculocutaneous nerve; Type II--double innervation by the musculocutaneous and radial nerves; Type III--double innervation by the musculocutaneous and median nerves; and Type IV--triple innervation by all three nerves. Single, double, and triple innervation patterns occurred 25%, 70% (Type II, 55%; Type III, 15%), and 5% of the samples, respectively. The brachialis muscle is not solely innervated by the musculocutaneous nerve but also by the radial and median nerves, thus making it a potentially triply innervated muscle. Double innervation of this muscle with either the musculocutaneous and median nerve or the musculocutaneous and radial nerves was also observed.
authors.affiliation: Department of Occupational Therapy, College of Health and Welfare, Woosong University, Daejeon, Korea.
authors.forename: Sung-Yoon
authors.initials: SY
authors.lastname: Won
authors.forename: Young-Hoon
authors.initials: YH
authors.lastname: Cho
authors.forename: You-Jin
authors.initials: YJ
authors.lastname: Choi
authors.forename: Vittorio
authors.initials: V
authors.lastname: Favero
authors.forename: Hee-Soon
authors.initials: HS
authors.lastname: Woo
authors.forename: Ki-Yeon
authors.initials: KY
authors.lastname: Chang
authors.forename: Kyung-Seok
authors.initials: KS
authors.lastname: Hu
authors.forename: Hee-Jin
authors.initials: HJ
authors.lastname: Kim
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001132:Arm / Q000294:innervation*; D002102:Cadaver; D005260:Female; D006801:Humans; D008297:Male; D008475:Median Nerve / Q000033:anatomy & histology*; D008875:Middle Aged; D018482:Muscle, Skeletal / Q000294:innervation*; D009138:Musculocutaneous Nerve / Q000033:anatomy & histology*; D011826:Radial Nerve / Q000033:anatomy & histology*
keywords: Sihler staining; brachialis; median; musculocutaneous; radial