Assertion: brachial plexus | /r/MadeOf | five roots
Facets:
Source sentences:
text: The brachial plexus is formed by five roots, the union of the anterior divisions of the lower four cervical nerves and the greater part of the anterior division of the first thoracic nerve; the fourth cervical usually gives a branch to the fifth cervical, and the first thoracic frequently receives one from the second thoracic.