Lectures

Medial Pectoral Nerve

by Stuart Enoch, PhD
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    00:01 Let’s start from the beginning. The first one is the lateral pectoral nerve. What does a lateral pectoral nerve supply? Pectoralis major.

    00:09 Pectoralis major, and what about the medial pectoral nerve? Pectoralis minor. Pectoralis minor, okay. The pectoralis major, since it’s a big muscle, it can be supplied by both, predominantly from the lateral pectoral nerve. But the medial pectoralis minor is supplied by the medial pectoral nerve.

    00:32 So that is your first nerve taken of pectoral. Next, the median nerve, who wants to tell me about median nerve? Tell me about median nerve. Where does it come from? What does it supply? So if you go back there, it comes from the -- C5, C6, C7, well, it comes from all of them. Exactly, yes, yeah, because it’s coming from the lateral cord, as well as the medial cord. So it’s from C5, C6, C7, C8, T1.

    01:11 You have the axillary artery here. That’s where it is. Then you have the lateral cord coming from there. And the medial cord coming from here, and they’re to join to form the median nerve. What does median nerve supply in the arm? Here.

    01:34 Nothing. Nothing. Very good. It doesn’t supply anything.

    01:38 Then it comes to the forearm. What does it supply in the forearm? Go on. Tell me.

    01:50 Does it supply all the muscles in the forearm or not? No. No. Okay. What doesn’t it supply? What does it not supply? The ulnar flexor of the -- Flexor carpi ulnaris, and? And the ulnar arch of the -- Very good.

    02:08 So ulnar half of the flexor digitorum profundus. These two are supplied by the ulnar nerve.

    02:14 Everything else that’s in the forearm is supplied by the median nerve. So, what are the muscles in the forearm at this level in the flexor compartment? Yes. We’ve got the profundus and superficialis and we’ve got palmaris longus, flexor carpi radialis, flexor carpi ulnaris, flexor -- we’ve got pronator quadratus.

    02:51 Fine, flexor digitorum superficialis. Okay, fine. I’ll go through those in detail.

    02:56 That’s fine. Does it supply anything else, the median nerve? Yes. Hand, so it comes to the hand. We’ll discuss that when it comes to the hand. So, what nerve supplies this part of the compartment of the arm? Musculocutaneous.

    03:09 Musculocutaneous. So, one thing you need to remember for the exam, everything in the flexor compartment of the arm, this part, his nice biceps, what are the muscles here? What are the muscles in the flexor compartment of the arm? Biceps, brachialis. And? And coracobrachialis. Coracobrachialis. Okay. So that is your BBC. BBC is biceps, brachialis, and coracobrachialis. They are the three muscles in the flexor compartment of the arm. They may ask you the origin of these are quite important, what’s the origin of biceps? You have a long head and the short head.

    03:56 Supraglenoid tubercle. Okay. The long head comes from the supraglenoid tubercle and the short head comes from the -- Coracoid process.

    04:03 Coracoid process. Okay. So that is their origin. Where does it insert? Radial -- Radial tuberosity. Coracobrachialis arises from the coracoid process, and where does it insert? Into the shaft of the humerus.

    04:25 Brachialis arises from the distal part of the shaft of the humerus. And where does it insert? Because the brachialis forms the floor of the cubital fossa. So, the brachialis is the most distal muscle here. It inserts into the radius and the ulnar lower down here.

    04:51 So that is your BBC supplied by the musculocutaneous nerve. What’s the root value of musculocutaneous? C5, C6, C7, because if you work it out, if you trace your lateral cord back, it’s from C5, C6, C7. So, three muscles supply the musculocutaneous, that is three letters, and three nerve roots, C5, C6, C7. So, that’s all you need to remember about the anterior compartment of the arm; musculocutaneous, three muscles, three nerve roots coming from the lateral cord. Right. So we have covered pectoral nerve, lateral root of median nerve and the medial root of median nerve, musculocutaneous nerve.

    05:46 Then you have the medial cutaneous nerve of the arm, which is here. Next is the medial cutaneous nerve of the forearm. So they are both our cutaneous components. And finally, the ulnar nerve. The ulnar nerve is extremely important. They will ask you a few things about ulnar nerve. One of them is which cord. So it’s coming from the medial cord, root values C8, T1. Just trace it back. I’m just tracing back your ulnar nerve.

    06:20 Okay. So, C8, T1. It is lying medial to the axillary artery. It’s medial here, comes all the way down. It’s quite superficial but it does not supply any of the muscles.

    06:37 Goes behind the medial epicondyle and it lays between two muscles here, which two muscles are they? It lays between the two heads of the flexor carpi ulnaris. So you have the flexor carpi ulnaris. It lies between the two heads, comes all the way down, and it supplies the flexor carpi ulnaris, and the ulnar half of flexor digitorum profundus to these fingers. It comes through the carpal tunnel. Does it go under the tunnel or -- It goes over. Yeah. It goes over the carpal tunnel but through the Guyon’s canal. So it’s very close to the pisiform bone. Then it comes to the palm of the hand, and then it supplies most of the small muscles in the hand, with an exception which we’ll come to when we discuss the hand. So that’s mainly your median nerve.

    07:35 So if you think about it now, you’ve covered all of the anterior aspect of the arm, the flexor aspect of the forearm because it’s separated by the median or the ulnar, nothing to do with the radial, nothing to do with musculocutaneous.


    About the Lecture

    The lecture Medial Pectoral Nerve by Stuart Enoch, PhD is from the course Musculoskeletal - Upper Limb.


    Author of lecture Medial Pectoral Nerve

     Stuart Enoch, PhD

    Stuart Enoch, PhD


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