Typological interrelationships of the human scalenus muscles, brachial plexus and subclavian artery

Dissection of 227 Japanese adult cadavers showed that the scaleus anterior and medius muscles are interconnected with each other by some muscle bundles which run between the roots of the plexus brachialis. The subclavian artery originates in the intersegmental arteries. Taking this fact into consideration, we illustrated a typological diagram which can explain some positional anomalies of the subclavian artery and the roots of plexus brachiails. The inconsistent scalenus minimus muscle may be an aberrant slip separated from the scalenus medius muscle by the subclavian artery which may originate in the fifth or sixth intersegmental artery.