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.
Procerus muscle Procerus muscle The procerus muscle (or pyramidalis nasi) is a small pyramidal slip of muscle deep to the superior orbital nerve, artery and vein. "Procerus" is Latin, meaning tall or extended. The procerus arises by tendinous fibers from the fascia covering the lower part of the nasal bone and upper part of the lateral nasal cartilage. It is inserted into the skin over the lower part of the forehead between the two eyebrows on either side of the midline, its fibers merging with those of the frontalis. The procerus helps to pull that part of the skin between the eyebrows