TY - CHAP M1 - Book, Section TI - The Forearm, Wrist, and Hand A1 - Malone, Terry R. A1 - Hazle, Charles A1 - Grey, Michael L. A1 - Hendrix, Paul C. PY - 2016 T2 - Imaging for the Health Care Practitioner AB - In the forearm, reference to normal anatomic relationships begins with the radius and ulna, proximal to distal. The distal radioulnar joint is a critical articulation in forearm pronation and supination. This joint has a separate synovial compartment and bordered distally by the triangular fibrocartilage.1 Generally, the radial styloid process extends beyond the ulnar styloid process by approximately 9 to 12 mm. At the proximal articular surface of the lunate, however, the two bones are of approximately of the same level. An ulna of less length provides for negative ulnar variance, and a longer ulna is described by a positive ulnar variance. The normal arrangement of the distal ulna and radius provides for the radial angle (also known as the ulnar slant or ulnar inclination), which is usually measured at 15° to 25°. The distal surface of the radius also demonstrates an orientation toward the palmar or volar surface of approximately 10° to 25°. These anatomic relationships are critical in imaging assessment for the orthopedist, both in assessing for pathology and in planning the appropriate course of intervention (Figures 13-1 and 13-2).1 SN - PB - McGraw-Hill Education CY - New York, NY Y2 - 2024/04/19 UR - accessphysiotherapy.mhmedical.com/content.aspx?aid=1128340814 ER -