Download Radial Nerve Anatomy

GOOD MORNING
RADIAL NERVE
 Dr .Qudsia Sultana
Objectives
 Origin
 Course & Relations
 Branches
 Distribution
 Applied Anatomy
Radial Nerve
 Originates as the
terminal branch of the
posterior cord of the
brachial plexus
 Roots from C5, 6, 7, 8, &
T1.
 Largest branch of
brachial plexus
 It is primarily a motor
nerve
Course – RN – Ant.view-Axilla
 It commences its
decent into the arm by
passing anterior to the
muscles forming
posteerior wall of
axilla.
Course of Radial Nerve
 Enters lower triangular
interval
 Teres major
(superior)
 Long head triceps
(medial)
 Humerus (lateral)
Course of R N
 Comes to lie in
distal part of spiral
groove with
profundi brachii
artery
 Beneath lateral
head of triceps
and proximal to
origin of medial
head
Course of Radial Nerve
 The lower portion of
the radial nerve
pierces the lateral
intermuscular
septum at
approximately 812cm from the
lateral epicondyle
and enters the lower
part of arm
Course of Radial Nerve
 In anterior compartment
of arm lies between
brachialis medially and
brachioradialis, Extensor
carpi radialis longus
laterally.
 In the cubital fossa divide
 Superficial radial
 Deep radial /Posterior
interosseous nerve
Course of Superficial Radial
Nerve
 Runs down the forearm
along the lat.border of
BR with radial artery on
its ulnar side in the
middle 1/3 of forearm
 Passes posteriorly
through tendon of BR
proximal to radial
styloid.
Course of Superficial R.Nerve
 Passes over tendons
of snuffbox
 Terminates as
cutaneous branches
to dorsum of hand
and lateral 3 1/2
digits except
nailbeds
Course – Posterior Interosseous
Nerve
 The Post Interosseous
Nerve continues down
the forearm dividng
between the heads of
supinator and then
emerging to split into
several branches that
supply the extensors of
the wrist and hand
APPLIED
ANATOMY
Lesions
 Level I – Axilla
 Level II – Spiral groove
 Level III – Elbow
 Level IV – Forearm
Axilla
 Lesions in the axilla
Involves the
posteriorcord / high
axillary lesions.
* Etiology:
Crutches / shoulder
dislocation
Position
• Hand hangs in flexion(wrist
drop)
• Wasting of dorsal arm
(triceps)& muscle mass on
the posterior surface of the
forearm
• Paraesthesias & sensory
loss on the entire extensor
surface of the arm &
forearm & on the back of
the hand & dorsum of the
first 4 fingers.
Spiral Groove
 Etiologies
Humeral factures/Compressive
lesions / Saturday night palsy
Entrapment by tendinous arch
of lateral head of triceps
muscle/damaged after arm
excercise .
Soldiers developing palsies at
the lateral border of humerus
after military shooting training
 Sensibility on the
extensor aspect of arm
is spared .
 Sensibility on the
extensor aspect of
forearm may or may
not be spared.
 Wrist drop + / No loss
of elbow extension
Elbow – Radial Tunnel Syn.
• Involvement of the
Post Interosseous N.
• Etiologies
A constricting band
at the radiohumeral
joint capsule.
Position
 Atrophy & paresis of
the ECU,ED,Extensor
digiti minimi
APL,EPL,EPB &
extensor indices.
 Extensor carpi radialis
is intact.
• Drop finger deformity
Difficulty in extending
the MCP of all five
fingers
 Partial wrist drop
 No sensory loss
 The wrist deviates
radially,when the
patient makes a fist.
Cheiralgia Paresthetica
• The superficial cutaneous branch of the radial
nerve → pure sensory syndrome that
affects the radial part of the dorsum of the
hand & dorsal aspect of the first 3 ½ fingers.
• Etiology:
Crushing/twisting injuries of the wrist/forearm
( “Hand-cuff / Wrist watch neuropathy” )
Repetitive pronation & supination.
Summary
 Radial nerve arises from posterior cord of the brachial
plexus
 It passes posterior to the axillary artery between long
and medial heads of triceps muscle, to lie in the spiral
groove between medial & lateral heads of triceps
muscle.
 Here it is accompanied by the profunda brachii artery
before it pierces lateral intermuscular septum of the
lower third humerus to run between brachialis &
brachioradialis
 At the lateral of epicondyle humerus, it gives rises to
PIN & superficial radial nerve
 Radial nerve supply all the extensor muscles of
forearm & arm. However it also supply brachioradialis,
which is flexor of elbow when forearm pronated.
 Damage to the nerve in the spiral groove causes
wrist drop but no loss of elbow extension, as fibres of
triceps remain intact proximal to this site.
 Only damage in the axilla will causes loss of elbow
extension & wrist drop
 Damage to posterior interosseus nerve (PIN) does
not cause wrist drop because extensor carpi radialis
longus receives its innervation from the main radial
nerve
 Pin only causes inability to extend
metacarpophalangeal joint  finger drop.