THE CLINICAL SIGNIFICANCE OF THE ARM BONY LANDMARKS IN CORRELATION TO THE RADIAL NERVE COURSE: AN ANATOMICAL STUDY

Abstract

The radial nerve is one of the most commonly injured nerves in long bone fractures. Knowledge of
the anatomy of the radial nerve is a key component for safety and successful surgical procedures about
the arm and the elbow. This study aimed to identify the level of the points at which the radial nerve
begins and ends its course on the posterior shaft of humerus in relation to the palpable anatomic bony
landmarks of the arm. The upper limbs of twenty adult human cadavers, ten males and ten females,
were used in this study. The specimens were obtained from the Anatomy Department, Faculty of
Medicine, King Abdul Aziz University. The limbs were dissected and the radial nerve of each was
exposed throughout its course within the arm. The distance between the points of both radial nerve
entry and exit on the spiral groove was measured in relation to different bony landmarks. The values
were measured in millimeters and in percentages in relation to the humeral length. The average
humeral length (from the postero lateral angle of acromion to the centre of lateral epicondyle) was 316
mm ± 5.5 in male upper limbs and 286 mm ± 15.4 in female upper limbs. The mean distance from the
point of radial nerve entry to the lateral angle of acromion, tip of the coracoid process, centre of lateral
and medial epicondyles was 143.3 ± 14 mm (44.5%), 131.7 ± 14.9 mm (42.5%), 174.2 ±13.3 mm
(55.5%) and 178.1± 15.2 mm(57.5%) in male upper limbs and they were 121.4 ± 10.4 mm (42.4%),
116.6 ± 12.3 mm (41.4%), 164.6 ± 1.9 mm (57.6%) & 166.3 ± 13.2 mm (58.6%) in female upper
limbs respectively. However, the mean distances from the point of radial nerve exit to same bony
landmarks were 214.2 ± 12.4 mm (67.7%), 205.6 ± 13.2 mm (66.4%), 102.5 ± 12.9 mm (32.3%),
104.7 ± 13 mm (33.8%) in male upper limbs and were 185.3 ± 14.6 mm(64.8%), 180.9 ± 13.4 mm
(64.8%), 100.3 ± 8 mm (35.1%), 101.3 ± 7 mm (36%) and 23.8 ± 6 mm (8%) in female upper limbs
respectively. Significant differences (P < 0.01) were reported between most of radial nerve
measurements of both male and female upper limbs with exception of the mean distance from the
point of radial nerve exit to the centre of both lateral and medial epicondyles. However, no significant
differences were recorded between the measurements of right and left upper limbs of male or female
cadavers. The palpable bony landmarks of arm provide an accurate data for the surgeon to determine
the location and to avoid the iatrogenic injury of the radial nerve during the surgical interventions of
the arm.
Key Words: Radial nerve, Bony landmarks, Humerus.