The Median Nerve Flashcards
What are the spinal roots of the median nerve?
C6-T1 (Also contains fibres from C5 in some individuals)
What are the motor functions of the median nerve?
Innervates most of the flexor muscles in the anterior compartment of the forearm
What are the flexor muscles within the superficial anterior compartment of the forearm?
Flexor carpi ulnaris (Innervated by the Ulnar nerve, not the median)
Palmaris Longus- Absent in about 15% of the population. The median nerve runs deep to this muscle.
Flexor Carpi Radialis
Pronator teres- The lateral border forms the medial border of the cubital fossa (An anatomical triangle located over the elbow.
Which flexor muscle is found within the intermediate anterior compartment of the forearm?
Flexor digitorum superficialis- Intermediate because in most people it lies between the deep and superficial muscle layers
It’s a good anatomical landmark as the median nerve and ulnar artery pass between its two heads and then travel posteriorly
What are the flexor muscles within the deep anterior compartment of the forearm?
Flexor digitorum profundus (FDP)- The medial half (which acts on the little and ring fingers) is innervated by the ulnar nerve. The lateral half (which acts on the middle and index fingers) is innervated by the anterior interosseous branch of the median nerve
Flexor pollicis Longus (FPL)- This muscle lies laterally to FDP and is innervated by the anterior interosseous branch of the median nerve
Pronator quadratus- Square shaped muscle found deep to the tendons of FDP and FPL. Also innervated by anterior interosseous branch of the median nerve
What are the actions of the muscles within the superficial anterior compartment of the forearm?
Flexor carpi ulnaris- Flexion and adduction at the wrist
Palmaris Longus- Flexion at the wrist
Flexor carpi radialis- Flexion and abduction at the wrist
What is the action of the muscle within the intermediate anterior compartment of the forearm?
Flexor digitorum superficialis- Flexes the metacarpophalangeal joints and proximal interphalangeal joints at the 4 fingers. Also, flexes at the wrist
What are the actions of the muscles within the deep anterior compartment of the forearm?
Flexor digitorum profundus- It’s the only muscle that can flex the distal interphalangeal joints of the fingers. It also flexes at metacarpophalangeal joints and at the wrist
Flexor pollicis longus- Flexes the interphalangeal joint and metacarpophalangeal joint of the thumb
Pronator quadratus- Pronates the forearm
What anatomical course does the median nerve take up to the cubital fossa?
The median nerve is derived from the medial and lateral cords of the brachial plexus (C5-T1)
It then descends down the arm, initially lateral to the brachial artery. Halfway down the arm, the nerve crosses over the brachial artery and becomes situated medially.
The median nerve enters the anterior compartment of the forearm via the cubital fossa.
What anatomical course does the median nerve take after passing through the cubital fossa?
The nerve travels between the flexor digitorum profundus and flexor digitorum superficialis.
It then gives rise to two major branches in the forearm:
Anterior interosseous nerve and the palmar cutaneous nerve
The median nerve then enters the hand via the carpal tunnel
What do the two major branches in the forearm of the median nerve supply?
Anterior interosseous nerve- Supplies the deep muscles in the anterior forearm
Palmar cutaneous nerve- Innervates the skin on the lateral palm
What anatomical course does the median nerve take after passing through the carpal tunnel?
It terminates by dividing into two branches:
The recurrent and the palmar digit branch
What do the two terminal branches of the median nerve supply?
Recurrent branch- Innervates the thenar muscles
Palmar digital branch- Innervates the palmar surface and fingertips of the lateral three and a half digits. Innervates the lateral two lumbrical muscles.
Which areas of the skin does the median nerve provide with sensation and how?
The median nerve is responsible for cutaneous innervation of part of the hand.
It gives rise to the palmar cutaneous branch it arises in the forearm and does not pass through the carpel tunnel. It innervates the lateral part of the palm.
The median nerve also gives rise to the digital cutaneous branch which innervates the lateral three and a half fingers of the anterior surface of the hand.
