INTRODUCTION:

The radial nerve is the largest branch of the posterior cord of the brachial plexus with a root value of c5-8, T1.

ORIGIN, COURSE & TERMINATION:

  • Radical nerve is given off from the POSTERIOR CORD or BRACHIAL PLEXUS in the lower part of axilla.
  • It runs behind the third part of axillary artery.
  • In arm, it lies behind the brachial artery.
  • It leaves the brachial artery to enter the lower triangular space to reach the oblique radical sulcus on the back of humerus.
  • The nerve reaches the lateral intermuscular septa to enter the anterior compartment of the arm on it's lateral aspect.
  • It descends down across the lateral epicondyle into the cubital fossa. The radical nerve terminates by dividing into the superficial and deep branches just below the level of the lateral epicondyle.

RELATIONS:

A. IN LOWER PART OF AXILLA- 

Radial nerve passes downwards and have the following relations:-
a. Anteriorly: Third part of the Axillary artery.
b. Posteriorly: Subscapularis, latissimus dorsi, and teres major.
c. Laterally: Axillary nerve and coracobrachialis.
d. Medially: Axillary Nerve.

B. IN THE UPPER PART OF ARM-

It continuous behind the brachial artery and passes posterolaterally through the lower triangular space below the teres major and between long head of the triceps, brachii and the humerus. It then enters the radial groove with profunda vessels.

C. IN THE RADIAL GROOVE:

It runs as downwards laterally between the medial and lateral head of tricep branchii, in contact with the humerus. At the lower end of groove 5cm below deltoid tuberosity, it pierces the lateral compartment of the arm to reach the. cubital fossa, where it ends by dividing into superficial and deep branches.

BRANCHES & DISTRIBUTION:

1. Muscular Branches:

  • In the AXILLA-  radial nerve supplies to the long and medial head of triceps branchii.
  • In the spiral groove- it supplies to the medial and lateral heads of triceps branchii and the anconeus.
  • Below the spiral groove- it supplies in the front arm, it supplies the brachialis with the proprioceptive fibers and the branchial radialis end Extensor Carpi radialis longus are supplied by motor fibers.

2. Cutaneous Branches:

  • In the Axilla- the nerves gave off posterior cutaneous nerve of the arm which supplies the skin on the back of the arm.
  • In the radial groove- it gives off lower lateral cutaneous nerves of the arm and Posterior cutaneous nerves of the forearm.

3. Articular Branches:

  • The articular branches lies near the elbow joint.