ðə pɹˈɪnsɛps pˈɑːlɪsˌɪs ˈɑːɹɾɚɹi, ɔːɹ pɹˈɪnsɪpəl ˈɑːɹɾɚɹi ʌvðə θˈʌm, ɚɹˈaɪzᵻz fɹʌmðə ɹˈeɪdɪəl ˈɑːɹɾɚɹi dʒˈʌst æz ɪt tˈɜːnz mˈiːdiːəli təwˈɔːɹdz ðə dˈiːp pˈɑːɹt ʌvðə hˈænd; ɪt dᵻsˈɛndz bᵻtwˌiːn ðə fˈɜːst dˈoːɹsəl ˌɪntɚɹˈɑːsiəs mˈʌsəl ænd ðɪ oʊblˈiːk hˈɛd ʌvðɪ ɐdˈʌktɚ pˈɑːlɪsˌɪs, ɐlˈɔŋ ðə mˈiːdiːəl sˈaɪd ʌvðə fˈɜːst mˌɛɾəkˈɑːɹpəl bˈoʊn tə ðə bˈeɪs ʌvðə pɹˈɑːksɪməl fˈælæŋks, wˌɛɹ ɪt lˈaɪz bᵻnˌiːθ ðə tˈɛndən ʌvðə flˈɛksɚ pˈɑːlɪsˌɪs lˈɔŋɡəs mˈʌsəl ænd dᵻvˈaɪdz ˌɪntʊ tˈuː bɹˈæntʃᵻz.
The princeps pollicis artery, or principal artery of the thumb, arises from the radial artery just as it turns medially towards the deep part of the hand; it descends between the first dorsal interosseous muscle and the oblique head of the adductor pollicis, along the medial side of the first metacarpal bone to the base of the proximal phalanx, where it lies beneath the tendon of the flexor pollicis longus muscle and divides into two branches.