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2. MOB TCD
Anatomy of Nerve Injuries
Upper Limb
Professor Emeritus Moira O’Brien
FRCPI, FFSEM, FFSEM (UK), FTCD
Trinity College
Dublin

3. MOB TCD
Anatomy of Nerve Injuries
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Dermatomes
Myotomes
Nerves entrapped
Pierce muscle
Pierce fascia
Repetitive movements

4. MOB TCD
Dermatomes
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Skin
Bones
Muscles, tendons
Nerves
Blood vessels

5. MOB TCD
Cutaneous Supply

6. MOB TCD
Extrinsic Factors
• External forces
• Fibro-osseous tunnels tether
the nerve
• Oedema
• Callus formation as a result of
a fracture
• External compression due to
specific movements
• Mechanical compression
• The nerve is tender at the site
of compression

7. MOB TCD
Extrinsic Factors
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Fibrous bands
Accessory muscles
Spurs
Narrow notches
Anatomical variations of the nerve
itself
• The most common symptom
complex involves the lower trunk
of the brachial plexus C8,T1
• With pain and paresthesia along
the medial border of the limb

8. MOB TCD
Extrinsic Factors
Congenital and structural
anomalies include:
• Cervical ribs
• Scalenus anterior syndrome
• Fibrous or fibro-muscular
bands

9. MOB TCD
Extrinsic Factors
• Costoclavicular, where it may also be
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•
•
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due to anatomical anomalies or
structural changes, e.g. shoulder
girdle depression
Between the pectoralis minor and the
coracoid process
The shoulder is very mobile and the
neurovascular structures may change
direction by a full 180°
The coracoid process and the pectoralis minor act as
a fulcrum for the change in direction
This is a potential site of compression

10. MOB TCD
Costoclavicular Compression
• Costoclavicular compression is
usually dynamic
• If you elevate the arm, the clavicle
rotates at the sternoclavicular and
acromioclavicular joints, narrowing
the costoclavicular space
• This space will be further
narrowed by retraction of the
shoulders, particularly if you are
carrying a heavy weight
• Deep inspiration elevates the first rib; this narrows the
space even further

11. MOB TCD
Brachial Plexus
• Roots arise from Anterior
Primary Rami
• C5
• C6
• C7
• C8
• T1
• Contribution from C4

12. MOB TCD
Brachial Plexus
• Roots unite to form trunks;
posterior triangle of neck
• C5, C6 form upper trunk
• C7 middle trunk
• C8,T1 form lowest trunk
• Branches arise mainly from
roots and cords
• Only 1 from upper trunk

13. MOB TCD
Brachial Plexus
• Roots between scalenus
anterior and scalenus
medius
• Trunks in the posterior
triangle
• Divisions behind clavicle
• Cords in axilla to lower
border of pectoralis minor

14. MOB TCD
Brachial Plexus

15. MOB TCD
Branches From Roots
• Branch to phrenic nerve C5
• Nerve to rhomboids or
dorsal scapular C5
• Nerve to subclavius
C5,C6, accessory phrenic
• Long thoracic nerve to
serratus anterior C5, C6, C7
along the side wall of thorax
• Kick or blow may affect rotation of scapula and
winging of scapula

16. MOB TCD
Brachial Plexus Entrapment
• Compression of
thoracic inlet
• Cervical rib
• Scalenus anterior or
fibrous band
• Back pack narrow
costoclavicular

17. MOB TCD
Suprascapular Nerve
• Upper trunk of brachial plexus
• C5, C6 in the posterior triangle
• Passes through suprascapular
foramen into the
• Supraspinous fossa supplies
suprascapular muscle
• Passes through the
spinoglenoid notch supplies
infraspinatus muscle
• Articular to shoulder joint

18. MOB TCD
Blood and Nerve Supply
• At spinoglenoid notch
only infraspinatus affected
√

19. MOB TCD
Cords of Brachial Plexus
• Outer border of first rib
• Divisions unite to form
cords
• Lateral, medial and
posterior cords, related to
first and second parts of
axillary artery
• End at lower border of
pectoralis minor

20. MOB TCD
Lateral Cord of Brachial Plexus
Lateral cord gives off:
• Musculocutaneous
• Lateral pectoral
• Lateral root of median nerve

21. MOB TCD
Medial Cord of Brachial Plexus
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Medial cutaneous of arm
Medial pectoral
Medial cutaneous of forearm
Medial root of median
Ulnar

22. MOB TCD
Posterior Cord of Brachial Plexus
• Axillary nerve
• Upper subscapular nerve
• Lower subscapular nerve,
subscapularis and teres major
• Nerve to latissimus dorsi
• Radial nerve

23. MOB TCD
Musculocutaneous Nerve
• Supplies and pierces
coracobrachialis
• Passes between
brachialis and
biceps supplying them
• Continues as
lateral cutaneous of forearm

24. MOB TCD
Lateral Cord of Brachial Plexus
• Lateral pectoral pierces the
clavipectoral fascia and
• Supplies pectoralis major
• Gives off the lateral root of
median nerve

25. MOB TCD
Axillary Nerve
• Posterior cord lower border of
pectoralis minor
• Quadrilateral space
• Upper lateral cutaneous nerve of
arm supplies skin over lower half
of deltoid
• Nerve to deltoid
• Nerve to teres minor
• Injury results in loss of sensation
over the lower half of the deltoid
• Weakness of the deltoid and the
teres minor

26. MOB TCD
Shoulder Relations
Anterior
• subscapularis
Posterior
• infraspinatus, teres minor
Superior
• long head of biceps
• supraspinatus
Inferior
• axillary nerve
In abduction
• long head triceps

27. MOB TCD
Shoulder Anterior Relations

28. MOB TCD
Axillary Nerve

29. MOB TCD
Axillary Nerve Compression
• Dislocated shoulder
• Quadrilateral space

30. MOB TCD
Radial Nerve
• In axilla
• Posterior cord: lower
border of pectoralis minor,
posterior to axillary artery
• Gives off posterior
cutaneous nerve of arm
• Supplies and then passes
between long and medial
head of triceps
• Injury in axilla e.g. crutches, Saturday night paralysis

31. MOB TCD
Radial Nerve
• In spiral groove
• Nerve to lateral and medial
head of triceps
• Posterior cutaneous nerve of
forearm
• Nerve to anconeus

32. MOB TCD
Radial Nerve - Spiral Groove
• Lies between brachioradialis
and brachialis and the extensor
carpi radialis longus
• Pierces lateral intermuscular
septum
• Brachioradialis and lateral
border of brachialis supplies
them
• Extensor carpi radialis longus
• Divides into superficial branch
• Posterior interosseus nerve

33. MOB TCD
Posterolateral
• Lies below head of radius
• Below lateral epicondyle
• Deep or posterior interosseous
supplies and then passes between
two heads of supinator
• Supplies the extensor carpi radialis
brevis
• Extensors from the lateral
epicondyle and all the deep
extensors of forearm

34. MOB TCD
Posterior Relations
• Superficial lies lateral to radial
artery in upper two thirds of
forearm
• Passes posterior to dorsum
• Pierces deep fascia
• Supplies posterior aspect of
forearm
• Skin of dorsum posterior
aspect of radial three and half
fingers

35. MOB TCD
Radial Nerve in Forearm
• Deep or posterior
interosseus nerve supplies
and then pierces supinator
• Muscles of posterior
compartment of forearm

36. MOB TCD
Radial Nerve
• Extensor digitorum communis,
extensor digiti minimi extensor
carpi ulnaris
• Abductor pollicis longus
• Extensor pollicis brevis
• Extensor pollicis longus
• Extensor indicis

37. MOB TCD
Elbow Nerve Compression
• Radial tunnel syndrome
• Posterior interosseous
nerve syndrome
• Cubital tunnel syndrome
• Pronator syndrome
• Anterior interosseous
nerve syndrome
Behr & Altchek, 1997

38. MOB TCD
Tennis Elbow Extensor Muscles
• Extensor carpi radialis brevis
in most cases
• Anterior edge of extensor
digitorum communis 30% less
frequently
• Extensor carpi radialis longus
• Extensor carpi ulnaris
Nirschl, 1993

39. MOB TCD
Posterior Relations of Elbow
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Triceps
Anconeus
Olecranon bursa
Ulnar nerve posterior to
medial epicondyle
• Common extensor origin

40. MOB TCD
Posterior Interosseous

41. MOB TCD
Deep Branch of Radial Nerve
Posterior Interosseus
• Supplies and then enters forearm
between the two heads of
supinator
• Extensor carpi radialis brevis
• Extensor digitorum communis
• Extensor indicis
• Extensor digiti minimus
• Extensor carpi ulnaris
• Extensor pollicis longus and brevis
• Abductor pollicis longus

42. MOB TCD
Radial Nerve in Forearm and Hand

43. MOB TCD
Radial Nerve in Forearm and Hand

44. MOB TCD
Anatomical Snuffbox
Medial
• Abductor pollicis longus
• Extensor pollicis brevis
• Both involved in De Quervain’s
syndrome
Posterior
• Extensor pollicis longus
Floor
• Distal end of radius and scaphoid
• Radial artery
Superficial
• Radial nerve

45. MOB TCD
Nerves in Forearm
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Posterior interosseus nerve
Supinator
Median nerve
Pronator teres
Ulnar nerve
Flexor carpi ulnaris

46. MOB TCD
Median Nerve
Median nerve
• Lower border of pectoralis minor
• Union of the two roots of median
• Anterior to axillary artery at first
• Then lateral and medial to
brachial artery
• Passes behind bicipital
aponeurosis
• No branches in arm
• Pronator teres

47. MOB TCD
Median Nerve in Forearm
• Median gives off branches to
flexor tendons
• Pronator teres, flexor carpi
radialis
• Pronator teres
• Flexor digitorium superficialis
• Passes between two heads of
pronator teres

48. MOB TCD
Median Nerve

49. MOB TCD
Median Nerve
• Passes deep to flexor digitorum
superficialis
• Gives off
• Anterior interosseous, supplies
flexor pollicis longus
• Radial one or two tendons of
flexor digitorum profundus
• Pronator quadratus

50. MOB TCD
Median Nerve
• Median passes deep to flexor
digitorum superficialis
• At wrist, posterolateral to
palmaris longus
• Gives off the superficial
palmar branch
• Passes superficial to flexor
retinaculum
• Main nerve goes deep to
retinaculum

51. MOB TCD
Carpal Tunnel
• No loss of sensation over skin of
palmar aspect of thenar eminence
• Loss over palmar aspect radial 3.5
fingers
• Wasting of thenar eminence
particularly abductor
pollicis brevis

52. MOB TCD
Wrist and Carpal Tunnel

53. MOB TCD
Wrist and Carpal Tunnel
• Median distal border gives off
motor branch to abductor pollicis
brevis
• Flexor pollicis brevis
• Opponens pollicis
• Unipennate lumbricals
• Cutaneous branches to radial
three and half and skin over the
dorsum of corresponding fingers

54. MOB TCD
Injury at Elbow
• Loss of sensation over skin
of palmar aspect of thenar
eminence
• Palmar aspect of radial
three and half fingers
• Wasting of thenar
eminence
• Weakness of superficialis
and one or two of
profundus tendons

55. MOB TCD
Median Nerve Lesion

56. MOB TCD
Compartment Syndrome
• Forearm is the most
common site of
compartment syndrome
• Anterior compartment of
the forearm may
compress median nerve
• Posterior compartment
• Mobile wad may be
altered sensation over the
dorsum

57. MOB TCD
Compartment Syndrome
• Windsurfing may cause
compartment syndrome in
flexor compartment
• Compression of median
nerve

58. MOB TCD
Blood and Nerve Supply

59. MOB TCD
Ulnar Nerve
• Lower border of pectoralis minor
from medial cord
• Medial to brachial artery
• Midway down
• Pierces medial intermuscular
septum, into posterior compartment
• Passes between two heads of
flexor carpi ulnaris
• Behind medial epicondyle to enter
anterior compartment of forearm
• No branches in the arm

60. MOB TCD
Ulnar Nerve

61. MOB TCD
Ulnar Nerve
• Supplies and then runs between
flexor carpi ulnaris and flexor
digitorum profundus
• Supplying medial two or three
tendons of flexor digitorum
profundus
• 5 cm above wrist gives off the dorsal
cutaneous branch skin of medial one
and half fingers

62. MOB TCD
Ulnar Nerve
• Passes superficial to flexor
retinaculum with artery on
lateral side, Guyons’ tunnel
• Supplies palmaris brevis
• Muscles of hypothenar
eminence
• Bipennate lumbricals
• Palmar and dorsal interossei
• Ends in adductor pollicis

63. MOB TCD
Ulnar Nerve

64. MOB TCD
Ulnar Nerve

65. MOB TCD
Ulnar Nerve
Compression at wrist affects
skin over palmar small
finger, half of the ring finger
and hypothenar muscles,
not skin over the dorsal
aspect.

66. MOB TCD
Ulnar Nerve Injury
• Rounded elbow in throwing
sports
• Javelin
• Discus puts tension on ulnar
nerve at elbow
• Electric shock along course of
nerve
• Late result of supracondylar
fracture

67. MOB TCD
Hamate
• Hook of hamate may fracture if
palm hits a wall
• Damage deep branch of ulnar
• Wasting of adductor pollicis
• 1st dorsal interossei

68. MOB TCD
Ulnar Nerve Paradox
• More deformity with an injury at
wrist than elbow
• Wasting of first web and guttering
due to wasting of interossei and
bilateral lumbricals
• Hyperextension of
metacarpophalangeal joints
• Flexion of proximal and distal
interphalangeal joints

69. MOB TCD
Grips

70. MOB TCD
Test for Ulnar Neuritis
• Tap ulnar nerve on
posteromedial aspect of
medial epicondyle
• Completely flex elbow and
hold for five minutes
• Positive is tingling along
nerve
Anderson & Hall, 1995

71. MOB TCD
Test for Medial Epicondylitis
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Stabilise flexed elbow
Palpate medial epicondyle
Slowly supinate the forearm
Extend wrist and elbow, while
patient resists
Anderson & Hall, 1995

72. MOB TCD
Elbow
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Biceps brachii
Brachialis
Triceps
Pronator teres
Supinator
Anderson & Hall, 1995
Musculocutaneous C5,C6
Musculocutaneous C5,C6
Radial C6, C7, C8
Median C6,C7
Posterior interosseous C5,C6

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