Download MBBS (Bachelor of Medicine, Bachelor of Surgery) Human Anatomy ppt lectures Topic 17 Median Nerve And Its Injury Notes. - anatomy ppt free download human anatomy ppt lectures, medicine notes ppt, anatomy handwritten notes pdf, mbbs 1st year anatomy notes pdf download, best anatomy notes pdf, human anatomy notes pdf, anatomy easy notes pdf, anatomy notes online, anatomy short notes, Anatomy ppt, Powerpoint Presentations and lecture notes.
Learning Objectives
1. Median nerve formation , root value and important
relations
2. Motor and sensory supply
3. Important sites of injuries/entrapment of nerve
4. Effects of injury of median nerve
5. How to clinically test median nerve injury
Q 1.Regarding the median nerve, all are correct
EXCEPT:
a. Arises from both the medial and lateral cords of the
brachial plexus.
b. It crosses the brachial artery at the insertion of the
coracobrachialis.
c. In the cubital fossa, it lies lateral to the brachial
artery.
d. It enters the hand in the carpal tunnel.
e. Injury of the nerve causes ape-like hand.
Q 1.Regarding the median nerve, all are correct
EXCEPT:
a. Arises from both the medial and lateral cords of the
brachial plexus.
b. It crosses the brachial artery at the insertion of the
coracobrachialis.
c. In the cubital fossa, it lies lateral to the brachial
artery.
d. It enters the hand in the carpal tunnel.
e. Injury of the nerve causes ape-like hand.
Answer c
Q 2. A 40 year tailor complains of pain numbness and weakness of right hand for last 3
months. On examination, there is hypoesthesia and atrophy of thenar eminence.
Which of the following nerve is likely to be involved?
A Ulnar nerve
B Median nerve
C radial nerve
D Axil ary nerve
Q 3 Injury to the median nerve in the arm would affect al of the following movements
except:
A. Pronation of the forearm
B. Flexion of the wrist
C. Flexion of the thumb
D. Supination of the forearm
Anatomy
? Mixed nerve (contain motor & sensory fibers).
? Root value: C 5,6,7,8 & T1
? Runs in the median plane of the forearm , so
its called median nerve
MEDIAN NERVE
? Formation:from two roots from
lateral cord
[C(5),6,7]&
from medial cord(C8,T1) of
brachial plexus
Before leaving axil a, C7 fibres
conveyed by median nerve are
handed over to Ulnar nerve
? These two roots embrace the third
part of axillary artery uniting
anterior or lateral to it
In the arm
? Closely related to the
brachial artery through out
the course in arm
? In the upper part it is
lateral to artey
? In the middle part it
crosses the artery from
lateral to medial side
? Remains on the medial
side up to elbow
Branches in arm
? Branch to Pronator Teres just above elbow
? Branch to brachial artery
? Branch to elbow joint at or just below the
elbow
In the cubital fossa
? Descends medial to
brachial artery
? Posterior to bicipital
aponeurosis
? Anterior to brachialis,
seperated by the
muscle from the elbow
joint
? Leaves the cubital fossa by passing
between two heads of pronator teres
In the forearm
? Enters the forearm between
the heads of pronator teres
? Crosses the lateral side of
ulnar artery from which it is
seperated by the deep head
of pronator teres
? Gives branch to pronator
teres while passing between
the two heads
? Proceeds behind a
tendinous ridge
between the two heads
of Flexor digitorum
superficialis and
anterior to Flexor
digitorum profundus
? Here it is accompanied
by median artery, a
branch of anterior
interosseous artery
? About 5 cm
proximal to flexor
retinaculum it
becomes
superficial
? Here it lies
between the
tendon of
palmaris longus
and the flexor
carpi radialis
muscle
? Leaves the forearm and enters the palm of the
hand by passing through the carpal tunnel deep to
flexor retinaculum
Branches in the forearm
? Muscular branches
to all the muscles
in the
superficial and
intermediate layer of
forearm except one
(FCU) originate
medially from nerve
just distal to elbow
joint
? Anterior interosseous
nerve: originate between
two heads of pronator teres
? passes distally down the
forearm with the anterior
interosseous artery.
? Innervates the muscles of
deep layer (FPL, lateral half
of FDP (for index and middle
finger) and pronator
quadratus)
Articular Branches -supply
elbow,superior and inferior
radio-ulnar joint, interosseous
membrane and wrist joint
?Palmar cutaneous branch: starts just proximal to flexor
retinaculum
?Lateral branches - thenar skin and connecting branch to
the lateral cutaneous nerve of fore arm
?Medial branches - central palmer skin and connecting
branch to the palmar cutaneous branch of the ulnar nerve
? Communicating branch:
multiple
?Arise in the proximal forearm
? Pass medialy between FDP &
FDS and behind the ulnar artery
to join the ulnar nerve
Median nerve in hand
? Proximal to flexor retinaculum it lies
between the tendons of FCR & FDS
overlapped by palmaris longus
? Distally it lies between the retinaculum and
the tendon in the retinaculum
? Site of compression
? Distal to retinaculum nerve enlarges and
flattens
? devides in to five or six branches
Branches in the hand
Lateral branch: gives
Recurrent
muscular branch-
short and
stout, curls upwards
over the distal border
of flexor retinaculum
and FPL to supply
three thenar muscles
APB, FPB &OP
? Three palmer digital
branches- First two
supply the skin of the
sides of the thumb ,its
web and distal part of
its dorsal surface.
? Third supplies the skin
of the radial side of
index finger and the
first lumbrical muscle
through its superficial
surface
? Medial branch: gives
? Two common palmar digital
branches- lateral and
medial which descend to
the interdigital clefts
between the index, middle
and ring finger
? Each nerve divides again
into two to supply adjacent
sides of the fingers
? So in total it supplies skin of
lateral three and half fingers
including the skin on the
dorsal aspect of terminal
phalanges
Injuries
? High
? Low
Median Nerve Lesion in Elbow Region ? High Lesion
? Damaged in
supracondylar fracture
of humerus
? Muscles af ected are:
? Pronator muscles of
the forearm
? All long flexors of
wrist and fingers
except FCU and
medial half of FDP
Motor Effects:
Wasting
of thenar
? Loss of pronation. Hand is kept in
eminence
supine position
? Wrist shows weak flexion, and
ulnar deviation
? Loss of flexion on interphalangeal
joints of the index and middle
fingers
? Weak flexion of ring and little
finger
Ulnar deviation
? Thumb is adducted and lateral y
rotated, with loss of flexion of
terminal phalanx and loss of
opposition
? Wasting of thenar eminence
? Hand looks flat ened and
"apelike", and presents an inability
to flex three most radial digits
when asked to make a fist.
? Sensory Ef ects: Loss of
sensation from:
? The radial side of the palm
? Palmar aspect of the lateral
3? fingers
? Distal part of the dorsal
surface of the lateral 3?
fingers
? Trophic Changes:
? Dry and scaly skin
? Easily cracking nails
? Atrophy of the pulp of
fingers
Median Nerve Lesion at Wrist
? Often injured by penetrating wounds (stab wounds or
broken glass) of the forearm.
? Motor:
? Thenar muscles are paralyzed and atrophy in time so thenar
eminence becomes flattened
? Opposition & abduction of thumb are lost, and thumb and
lateral two fingers are arrested in adduction & hyperextension
position .
? "Apelike hand"
? Sensory & trophic changes are same as in elbow
region injuries
Examination
? Flexor pol icis longus : Tested by holding
thumb at its base and patient asked to flex the
terminal phalanx
Examination
? Flexor digitorum superficialis & profundus
(Ochsner's clasping test)
- Patient is asked to clasp the hands , the index
finger of af ected side fails to flex
Examination
? Flexor Carpi radialis : Hand deviates to the
ulnar side when flexed against resistance
Examination
? Muscles of Thenar eminance:
-abductor pol icis brevis (Pen test)
- hand laid flat on the table
-pen held above the palm and the patient is
asked to touch the pen with his thumb
Examination
? opponens pol icis : brings the tip of the
thumb towards the tips of other fingers
Opponens pollices
Benedict Sign
Lesion to upper arm area, just proximal to where motor
branches of forearm flexors originate, is diagnosed if the
patient is unable to make a fist.
More specifically, the patient's index and middle finger
cannot flex at the MCP joint, while the thumb usually is
unable to oppose. This is known as hand of benediction or
Pope's blessing hand.
Benedict Sign
Kiloh-Nevin syndrome and OK Sign
The Anterior Interosseus Nerve (AIN) syndrome
Patients suffering from this syndrome have impaired distal
interphalangeal joint, because of which they are unable to
pinch anything or make and "OK" sign with their index finger
and thumb. The syndrome can either happen from pinched
nerve, or even dislocation of the elbow.
Kiloh-Nevin syndrome OK Sign
After history of stab wound on front of forearm , patient
presents with impairment of the pincer movement and is having
difficulty picking up a small item, such as a coin, from a flat
surface. Which of the following statement is correct ?
A Injury to anterior interroseous nerve of median nerve
B injury to main median nerve as pincer movement involves FDS
C Injury to ulnar nerve
D. Injury to median nerve at level of wrist
Ape hand deformity
In "Ape hand deformity", the thenar muscles become
paralyzed due to impingement and are subsequently flattened.
it is seen only after the thenar muscles have atrophied. While
the adductor pollicis remains intact, the flattening of the
muscles causes the thumb to become adducted and laterally
rotated. The opponens pollicis causes the thumb to flex and
rotate medially, leaving the thumb unable to oppose.
Ape Thumb
Median nerve Compression
Syndromes
? Carpal Tunnel ?nerve may be compressed due to
inflammatory condition of ulnar bursa or anterior
dislocation of lunate bone
? Pronator
? Interosseous
Carpal Tunnel Syndrome
? Compressive neuropathy as the nerve passes through the
Carpal Tunnel
? Causes:
- Idiopathic
: Most common
- Inflammatory : Rheumatoid Arthritis
: Wrist osteoarthritis
- Post traumatic : Bone thickening
- Endocrine
: Myxoedema
: Acromegaly
- Pregnancy
- Gout
- Repetitive wrist movts: Typists & Computer users
Carpal Tunnel Syndrome
? The commonest neurological
problem associated with median
nerve is compression beneath
flexor retinaculum at wrist.
? Motor: Weak motor function of
thumb, index & middle finger
? Sensory: Burning pain or `pins
and needles' along distribution
of median nerve to lateral 3?
fingers
No sensory changes over palm as palmer cutaneous branch
is given before median nerve enters carpal tunnel.
Symptoms
? Hand and wrist Pain
? Paraesthesia
? Hypoaesthsia
? Sparing of Palmar cutaneous branch supply
? Patient wakes at night with burning or aching
pain and shakes the hand to obtain relief and
restore sensation
? Aggravated by elevation of hand
? Thenar atrophy and weakness of thumb
opposition and abduction may develop late
Diagnosis
? History
? Clinical examination:
- Thenar wasting
- Phalen's sign
- Tinel's sign
- Carpal compression test
? Electro Diagnostic Studies:
- Very reliable for evaluation
- Atypical cases may be present
Thenar atrophy
Phalen test
A positive Phalen test is highly suggestive of carpal tunnel
syndrome.
Phalen's test is performed by having patients place their wrists in
complete unforced flexion for at least 30 seconds.
If the median nerve is entrapped at the wrist, this maneuver will
reproduce the symptoms of carpal tunnel syndrome.
Tinel's Sign
Carpal Compression test/ Durkan's test
Pronator teres syndrome
? High Compression neuropathy
? It is rare compared to CTS and AIS
Pronator teres syndrome
The characteristic physical finding is tenderness over the
proximal median nerve, which is aggravated by resisted
pronation of the forearm.
The flexor pol icis longus and FDP of the index finger are weak,
leading to impairment of the pincer movement. This reflects
involvement of the anterior interosseous nerve.
Sensory changes may be found in the first three fingers as well
as in the palm, indicating impairment of the median nerve
proximal to the flexor retinaculum.
Symptoms & signs
? Symptoms are similar to those of carpal tunnel syndrome
? Sensory disturbances
- Thumb & Index > Middle finger
? Night pain is unusual and forearm pain is more common
? Hand numbness on gripping
? Phalen's test negative
? Double crush phenomena
? Symptoms provoked by resisted elbow flexion with forearm
supinated ( tightening of bicipital aponeurosis )
? By resisted forearm pronation with the elbow extended (
pronator tension )
This post was last modified on 05 April 2022