Radius (bone) in the grooves on the lower end of the bone. The lateral surface ("facies lateralis; external surface") is convex throughout its entire extent and is known as the convexity of the radius, curving outwards to be convex at the side. Its upper third gives insertion to the supinator muscle. About its center is a rough ridge, for the insertion of the pronator teres muscle. Its lower part is narrow, and covered by the tendons of the abductor pollicis longus muscle and extensor pollicis brevis muscle. The upper extremity of the radius (or proximal extremity) presents a head, neck, and tuberosity.
Geniohyoid muscle artery. The geniohyoid muscle is innervated by fibres from the first cervical nerve travelling alongside the hypoglossal nerve. These fibers are called ansa cervicalis. It may be blended with the one on opposite side or double; slips to greater cornu of hyoid bone and genioglossus occur. The geniohyoid muscle brings the hyoid bone forward and upwards. This dilates the upper airway, assisting respiration. During the first act of deglutition, when the mass of food is being driven from the mouth into the pharynx, the hyoid bone, and with it the tongue, is carried upward and forward by the anterior bellies