MEDIAN NERVE | ANATOMY | SIMPLIFIED

Summary

This video provides a detailed overview of the median nerve, the primary nerve of the anterior forearm, responsible for controlling fine hand movements and supplying the thenar eminence. It explains the nerve's course from the arm, its relationship with the brachial artery, through the forearm between key muscles, and into the hand via the carpal tunnel. The video also covers its branches, including muscular, vascular, cutaneous, and articular branches, and highlights clinical relevance such as carpal tunnel syndrome, which affects sensation and thumb function. Clear explanations, diagrams, and key points make this a comprehensive guide for understanding median nerve anatomy and function.

Takeaways

• 🫀 The median nerve is the main nerve of the anterior forearm and controls coarse movements of the hand.
• 💪 It supplies the muscles of the thenar eminence and most of the long muscles of the forearm.
• 🧬 The root values of the median nerve are C5 to T1.
• 🩺 In the arm, the median nerve is lateral to the brachial artery in the upper part, crosses to the medial side in the middle, and lies medial at the cubital fossa.
• 🤲 In the forearm, the median nerve passes between the two heads of pronator teres, beneath the fibrous arch of flexor digitorum superficialis, and over flexor digitorum profundus.
• ✋ At the wrist, it lies deep to the flexor retinaculum and enters the palm through the carpal tunnel.
• 🔗 Branches of the median nerve include muscular branches to forearm muscles, the anterior interosseous nerve, vascular branches, communicating branch to ulnar nerve, palmar cutaneous branch, and articular branches.
• 🖐 In the palm, the median nerve divides into lateral and medial divisions supplying thenar muscles, lateral 1½ digits, and adjacent sides of index, middle, and ring fingers.
• ⚠️ Carpal tunnel syndrome is caused by compression of the median nerve under the flexor retinaculum, leading to thenar muscle wasting, sensory loss in lateral 2/3 of the palm and lateral 3½ digits, and thumb deformity.
• 📝 Clinical testing of median nerve function includes the paper-holding test to assess thumb opposition.

Q & A

What is the primary function of the median nerve?

The median nerve is the main nerve of the anterior forearm and controls most of the long muscles of the forearm, enabling fine movements of the hand. It also supplies the thenar eminence muscles.

What is the root value of the median nerve?

The root value of the median nerve is C5 to T1.

Describe the course of the median nerve in the arm.

In the upper arm, the median nerve lies lateral to the brachial artery. In the middle of the arm, it crosses anteriorly from lateral to medial. In the lower arm and cubital fossa, it lies medial to the brachial artery, behind the bicipital aponeurosis and anterior to the brachialis muscle.

How does the median nerve enter the forearm?

The median nerve enters the forearm by passing between the two heads of the pronator teres muscle and passes beneath the fibrous arch of the flexor digitorum superficialis, running deep to this muscle and over the flexor digitorum profundus.

Where does the median nerve lie at the wrist before entering the palm?

Five centimeters above the wrist, the median nerve becomes superficial, lying between the tendons of the flexor carpi radialis laterally and flexor digitorum superficialis medially, and lateral to the palmaris longus tendon. It then passes deep to the flexor retinaculum through the carpal tunnel.

What are the branches of the median nerve in the cubital fossa?

In the cubital fossa, the median nerve gives a muscular branch to the pronator teres, a vascular branch to the brachial artery, and an articular branch to the elbow joint.

Which muscles are supplied by the anterior interosseous branch of the median nerve?

The anterior interosseous nerve, the deep branch of the median nerve, supplies the lateral half of the flexor digitorum profundus, the flexor pollicis longus, and the pronator quadratus.

How does the median nerve supply the hand?

In the palm, the median nerve divides into lateral and medial divisions. The lateral division supplies the thenar muscles and three digital branches for the lateral 1½ digits (thumb and lateral side of the index finger). The medial division divides into two common digital branches supplying the adjoining sides of the index, middle, and ring fingers.

What is the clinical significance of the median nerve in carpal tunnel syndrome?

In carpal tunnel syndrome, compression of the median nerve under the flexor retinaculum leads to wasting of the thenar muscles, loss of sensation in the lateral 2/3 of the palm and lateral 3½ digits, and thumb deformity with inability to oppose the thumb. It is often tested using the paper-holding test.

What is the anatomical relationship of the median nerve to the brachial artery throughout the arm?

The median nerve is lateral to the brachial artery in the upper arm, crosses anteriorly to lie medial in the middle arm, and in the lower arm and cubital fossa, it is medial to the artery behind the bicipital aponeurosis and anterior to the brachialis.

Which cutaneous area is supplied by the palmar cutaneous branch of the median nerve?

The palmar cutaneous branch arises above the flexor retinaculum and supplies the lateral two-thirds of the palm.