Upper Limb

1. MEDIAN NERVE
Dr M Idris Siddiqui

2. Learning objectives
–The applied anatomy of the median
nerve
–Its anatomical course,
–Motor functions and
–Cutaneous innervation.
–The clinical correlations of damage to
the median nerve.

4. Median nerve:
• Arises in the axilla by two roots
lateral (C5, C6, and C7) and
medial (C8 and T1) from
the lateral and medial cords of
brachial plexus.
• Its root value is C5, C6, C7, C8,
and T1 spinal segments .

5. Median nerve enters the anterior compartment of arm at the
lower border of teres major.
In the arm, initially it lies lateral to the brachial artery, then crosses
in front of the artery to reach its medial side. (i.e., level of
insertion of coracobrachialis).
Enters the cubital fossa where it lies medial to the brachial artery.
It leaves the cubital fossa by passing between the two heads of the
pronator teres and gives off anterior interosseous nerve.
In the forearm , it passes behind (the tendinous arch) of flexor
digitorum superficialis and runs downwards deep to the muscle.
At the wrist,5 cm. proximal to flexor retinaculum it becomes
superficial exactly in the midline.
It then enters the palm through the carpal tunnel (deep to flexor
retinaculum) and divides into lateral and medial terminal
branches.

7. The Median Nerve
in the axilla
• The medial root crosses in front of
the third part of axillary artery to
connect with the lateral root in a
Y-shaped manner possibly in front
of or on the lateral side of the
artery to compose the median
nerve.

10. IN THE CUBITAL FOSSA
• In the cubital fossa, it lies in front of the brachialis
muscle.
• The median nerve lies medial to the brachial
artery and tendon of biceps brachii.
– Here it is protected by bicipital aponeurosis,
which divides it from the median cubital vein.
• Then on the medial side of the ulnar artery.
• It gives muscular branches from its medial side to
supply all the superficial flexors of the forearm (flexor
carpi radialis, palmaris longus, and flexor
digitorum superficialis) other than flexor carpi
ulnaris.

13. Distal to cubital fossa
• Median nerve gets out of the cubital fossa by passing
between the two heads of pronator teres crossing in front of
the ulnar artery( but separated from it by the ulnar head of
pronator teres).
–At this point, it gives off anterior interosseous
nerve.
• The anterior interosseous nerve is purely motor
and supplies muscles:
–Flexor pollicis longus.
–Lateral half of the flexor digitorum
profundus .
–Pronator quadratus.
2 ½

15. The Median Nerve
• In the forearm, the nerve travels between
the flexor digitorum profundus and flexor
digitorum superficialis muscles.
• The median nerve gives rise to two major
branches in the forearm:
–Anterior interosseous nerve – Supplies the deep
muscles in the anterior forearm.
–Palmar cutaneous nerve – Innervates the skin of
the lateral palm.
• The median nerve enters the hand via the carpal tunnel.

17. Proximal to the flexor retinaculum
• About 5 cm proximal to the flexor
retinaculum, the median nerve arises
from the lateral side of the flexor
digitorum superficialis and becomes
superficial, exactly in the midline.

19. CARPAL TUNNEL
• Median nerve gets in the palm by passing
through carpal tunnel where it is located deep
to flexor retinaculum and superficial to the
tendons of flexor digitorum superficialis,
flexor digitorum profundus, and Flexor pollicis
longus.
• Median nerve ends in the carpal tunnel
dividing into 2 terminal branches.
–Lateral (smaller)
–Medial (larger)

20. PALM
• In the palm,
The lateral division gives
• a recurrent branch, which curls upwards to supply
thenar muscles except the deep head of flexor
pollicis brevis.
• It then splits into three palmar digital branches.
The medial divisions give off
• Two palmar digital nerves.
• The five palmar digital nerves supply:
–Sensory innervation to the skin of the palmar aspect of the
lateral 3⅟₂ digits o sisti g of ail eds a d ski o the dorsal
aspect of distal phalanges, and first and second lumbricals.

21. Median nerve
• It is cutaneous to the flexor surfaces and nail beds of
the three and a half radial digits and a corresponding
area of palm.
• Median nerve is also termed laborer s nerve since the
coarse movements of the hand required by laborers
(e.g., digging the ground, lifting weight, etc.) are carried
out by long flexors of the forearm which are mostly
supplied by the median nerve.
• It is also called eye of the hand or peripheral
eye because it offers sensory innervation to the pulp of
the thumb and index finger which are used to see the
thinness and texture of cloth and are also used for
doing fine movements, e.g., buttoning a coat.

23. Branches and distribution
In the axilla and arm No branches
In the cubital fossa From its medial side to the all the superficial flexors of the
forearm except flexor carpi ulnaris.
In the forearm Anterior interosseous branch supplies 2 ½ muscles:
Flexor pollicis longus
Pronator quadrates
Lateral half of the flexor digitorum profundus.
Palmar cutaneous branch:
Before entering carpal tunnel it gives off palmar cutaneous
branch ( passes superficial to flexor retinaculum) which
supplies skin over thenar eminence and lateral part of palm.
In the palm Lateral branch gives:
•A recurrent branch that supplies thenar except
adductor pollicis.
•Three palmar digital branches.
Medial branch gives:
• Two palmar digital branches.
•The five palmar digital nerves supply:

25. The Median Nerve
• Motor functions: Innervates the flexor
muscles in the anterior compartment of the
forearm
–(except the flexor carpi ulnaris and part of the
flexor digitorum profundus, innervated by
the ulnar nerve).
• Also supplies innervation to the thenar
muscles and lateral two lumbricals in the
hand.

26. Motor Functions
• The median nerve innervates the
majority of the muscles in the anterior
forearm.
–In general, these muscles perform
pronation of the forearm, flexion of the
wrist
• Some intrinsic hand muscles.
–only the three thenar muscles and two
lumbricals which perform flexion of the digits of the
hand.

27. Sensory Functions
• The median nerve is responsible for the cutaneous
innervation of part of the hand. This is achieved via
two branches:
• Palmar cutaneous branch – Arises in the forearm
and travels into the hand. It innervates the lateral
aspect of the palm. This nerve does not pass
through the carpal tunnel, and is spared in carpal
tunnel syndrome.
• Palmar digital cutaneous branch – Arises in the
hand. Innervates the palmar surface and fingertips
of the lateral three and half digits.

28. The Median Nerve

30. CLINICAL RELEVANCE
• INJURIES OF THE MEDIAN NERVE
• The lesions of median nerve may take
place at the following four sites:
–(a) at elbow,
–(b) at mid-forearm,
–(c) at wrist (distal forearm), and
–(d) in the carpal tunnel.

31. Lesions Motor deficit: Sensory deficit
Lesions above the
elbow
•Supracondylar
fracture of humerus,
•Application of tight
tourniquet during
venipuncture
Loss of pronation of forearm
Weakness in flexion of the hand at the
wrist
Loss of flexion of thumb, 2nd and 3rd digits
Loss of abduction and opposition of thumb.
Fixed hyperextension of index finger,
middle finger and thumb
Loss of sensation in the
thumb, 2nd and 3rd
digits, and the thenar
area.
Lesions between
elbow and wrist
Loss of pronation of forearm
Loss of flexion of thumb, 2nd and 3rd digits
(pointing index finger)
Loss of abduction and opposition of thumb.
Loss of sensation in the
thumb, 2nd and 3rd
digits, and the thenar
area.
Lesions proximal to
the carpal tunnel
•deep lacerated wounds
(cut injury), e.g., suicidal
cuts.
Loss of flexion of thumb, 2nd and 3rd digits
Loss of abduction and opposition of thumb.
Loss of sensation in the
thumb, 2nd and 3rd
digits, and the thenar
area
Lesions within the
carpal tunnel
Loss of flexion of thumb, 2nd and 3rd digits
Loss of abduction and opposition of thumb.
Ape-thumb deformity
Loss of sensation in the
thumb, 2nd and 3rd
digits,
but excluding the
thenar eminence

32. INJURY IN THE CARPAL TUNNEL
• Carpal tunnel syndrome. The median nerve is
injured in the carpal tunnel due to its compression.
– Feeling of ur i g pai or pi s a d eedles alo g the
sensory distribution of median nerve (i.e., lateral 3 1 / ₂
digits) especially at night.
– There is no sensory loss over the thenar eminence
because skin over thenar eminence is supplied by the
palmar cutaneous branch of the median nerve, which
passes superficial to flexor retinaculum.
– Weakness of thenar muscles.
– Ape-thu defor ity ay o ur, if left u treated, due
to paralysis of the thenar muscles.