Frequency and characterization of the accessory heads of the biceps brachii: A multicentric cadaveric study

•Investigation of the frequency and different types of biceps brachii muscle (BBM) accessory heads.•Description of the different origins and insertions from BBM accessory heads.•Morphological and morphometric characterization of BBM accessory heads. The biceps brachii muscle (BBM) is a large and thick muscle on the ventral portion of the upper arm. The scientific literature reports the existence of extra heads. The present work investigated the frequency of occurrence of BBM accessory head(s) in four different Anatomy Laboratories at universities in Northeast Brazil. Once the upper limbs with an anatomical variation of the BBM heads were identified, the accessory head was evaluated for morphometric characterization (the length, width, and thickness). The sample consisted of 249 upper limbs and the outcomes were 26 members with BBM accessory heads (10.44% of the total sample). Among the 26 members studied was found a single accessory head in 22 (84.62%), two accessory heads in 3 (11.54%), and three accessory heads in 1 (3.85%). BBMs with one, two, and three accessory heads were found, with different origins. The average length, width, and thickness of these accessory heads were 169.39mm, 10.25mm, and 3.39mm, respectively. The frequency of BBM accessory heads in a population of northeastern Brazil in this cadaveric study was 10.44%.