ANNALS OF ANATOMY Cutaneous nerve to the subacromial region originating from the lateral pectoral nerve Keiichi Akita, Tomokazu Kawashima*, Takashi Shimokawa, Kenji Sato*, and Tatsuo Sato Unit of Functional Anatomy, Graduate School, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8519, Japan, and *School of Allied Health Sciences, Faculty of Medicine, Tokyo Medical and Dental University, Tokyo, Japan Summary. During dissection practice, a cutaneous branch to the deltoid region, which originated from the lateral pectoral nerve, was found bilaterally in one Japanese male (two of 125 sides, 1.6%). The branch originated from the superior surface of the lateral pectoral nerve, ran on the superior surfaces of the coracoid process and the coraco-acromial ligament, and pierced the deltoid muscle close to the tip of the acromion. The distribution area of this cutaneous branch was similar to the cuta- neous branch of the suprascapular nerve. Although the branch from the suprascapular nerve has been reported in man and primates, a minute description of such a branch from the lateral pectoral nerve is not currently available in the literature. According to the detailed ana- lyses of the roots of the lateral pectoral nerve and the su- prascapular nerve, the roots of both nerves are close to each other in the upper part of the superior trunk of the brachial plexus. Therefore, these cutaneous branches have different courses, but are considered to be a single nerve to complement the supraclavicular nerves. Key words: Subacromial cutaneous branch - Lateral pec- toral nerve - Suprascapular nerve - Cutaneous branch - Human gross anatomy Introduction A cutaneous nerve to the subacromial region, which origi- nated from the lateral pectoral nerve, was found bilaterally in one male during the dissection practice. A detailed de- scription of such a branch of the lateral pectoral nerve is not currently available in the literature. The distribution of Correspondence to: K. Akita E-mail: akita.fana@tmd.ac.jp this cutaneous branch was similar to the cutaneous branch of the suprascapular nerve, which has been reported in man (Spalteholz 1903; Murakami et al. 1977; Horiguchi 1980; Yamada 1984; Yamada and Mannen 1985; Horie 1992). The authors investigated the cutaneous branches of the deltoid region to compare the subacromial cutaneous branches of the lateral pectoral nerve and the suprascapu- lar nerve, and the nerve from the supraclavicular nerve which was found in four sides of three bodies. It has been discussed that the suprascapular nerve has been traced into the anterior division of the brachial plexus or the posterior division (e.g. Kerr 1918; Cheng 1955; Ballard 1964; Kato 1989; Kodama et al. 1992 a; Yan et al. 1999). The lateral pectoral nerve is generally consid- ered to be traced into the anterior division of the brachial plexus. It is very interesting that the subacromial cuta- neous nerves from the suprascapular nerve and the lateral pectoral nerve are distributed to the same region. In the present study, we report the origin, course and distribu- tion of these cutaneous nerves, and discuss the relation- ships between two cutaneous nerves originating from the different nerves. Materials and methods Observations on the shoulder regions were made on 125 sides of 63 Japanese cadavers during student dissection practice in 1999 and 2000. In all cadavers, seven cervical vertebrae were found, and we did not find any cervical ribs. A subacromial cutaneous nerve originating from the lateral pectoral nerve was found bilat- erally in a male and in the right side of a male. A cutaneous nerve originating from the suprascapular nerve was observed in four sides in three bodies (one male and two females). Upon minute dissection and thorough analysis of the brachial plexus, these cutaneous nerves were examined and then recorded using photos and sketches. Ann Anat (2002) 184:15-19 © Urban & FischerVerlag http://www.urbanfischer.de/journals/annanat 0940-9602/02/184/1-15 $15.00•0