This document provides an overview of upper extremity anatomy as it relates to brachial plexus blocks. It discusses the branches and innervation of the brachial plexus, as well as anatomical variations that are important to consider when performing blocks. Specific techniques like interscalene, supraclavicular, infraclavicular, and axillary blocks are described, highlighting relevant landmarks, spread of local anesthetic, and risks like phrenic nerve palsy or pneumothorax. Detailed dissections of the brachial plexus at different levels are also shown.

1. ANATOMY, A LAUNCH PAD FOR RA!
UPPER EXTREMITY ANATOMY
DR KALPESH SHAH
M.D.,D.A (Anaesthesia )
Consultant Anaesthesiologist
Mumbai

2. “The understanding of innervations are of basic
importance and is the basis for
Neuro-electrostimulation.”
Dr Sandip Diwan
(Regional Nerve Blocks book)

3. Brachial plexus block becomes the analogues to
epidural anaesthesia, i.e. once the compartment is
entered ,a single injection of an adequate volume
of local anesthetic results in successful
anaesthesia.

4. BRANCHES OF BRACHIAL
PLEXUS

6. DERMATOMES

7. SCHEMATIC DIAGRAM OF BRACHIAL
PLEXUS

8. GROSS ANATOMICAL
RELATION OF BRACHIAL
PLEXUS AT NECK

10. DISSECTION AT NECK

12. DISSECTION OF NECK

14. ORIENTATION OF
‘ BRACHIAL LINE’

16. SCLEROTOME (ANT.)

17. SCLEROTOME (POST.)

18. DIVISIONS
• Each trunk divides to form an anterior and
posterior division posterior to the mid clavicle.
• In general, anterior divisions supply muscles of the
anterior compartments (flexors) where as the
posterior division supply muscles of the posterior
compartments(extensors)
• No branches arises from the divisions.

19. • The dorsal rami course posteriorly into the spinal
extensors (erector spine)and do not contribute to
the brachial plexus.
• The ventral rami of C4 & C5 also contribute to
the brachial plexus
• The ventral ramus of T1 also contribute to the
first intercostal nerve.

20. DISSECTION AT THE LEVEL
OF CORDS

22. INTERSCALENE BLOCKS

23. • The ant scalene muscle arises from anterior
tubercle of the transverse process of the 3
rd,4 th,5 th and 6 th cervical vertebra.
• It inserts on the scalene tubercle of the first
rib.
• Brachial plexus is situated lateral and
superior to the subclavian artery.

24. • Middle scalene muscle arises from the
posterior tubercles of the transverse process
of lower six cervical vertebrae.
• The trunks that are stacked on each other
now divides into anterior and posterior
division are enclosed in the scalene sheath
and come to lie superolateral to the
subclavian artery.

25. • The topography changes from almost vertical
arrangement of trunks of brachial plexus to a
horizontal one.
• Quiet often, the trunks are short in length and
divide and rejoin immediately at the
supraclavicular area(division), thus at times the
interscalene or supraclavicular produces mixed
neurostimulation induced evoked muscle
response.

27. PREVERTEBRAL FACIA
• The prevertebral fascia of the neck
extends down to ensheth the axillary
artery and cords.
• It is this axillary sheath that local
anesthetic is injected when performing the
brachial plexus block

28. • Once the needle tip penetrates the
prevertebral cervical fascia its really
undecided whether the tip is in the
interscalene groove or in the anterior or
middle scalene muscle.
• Increasing resistance on bolus injection will
suggest the tip in the muscle ,while a smooth
flow will be definitive that tip is in the groove.

29. ANATOMICAL VARIATIONS
• Commonly described anatomical relationship
of brachial plexus lying between the anterior
scalene and middle scalene muscle was
found in only 60% of instance.
• The most common variation was the
penetration of AS by the C5 and/or C6 ventral
rami.

30. • The C5 &C6 roots may fuse before
piercing Anterior Scalene. (15%cases).
• The C5 root alone pierce the belly of AS
(13%cases)
• The C5 root was found completely anterior
to AS in 3% of cases.

31. • VERTEBRAL FORAMEN IS AT A
DISTANCE OF 3.7 CMS APPROX FROM
SKIN…..BEWARE OF INTRAFORAMINAL
INJECTION

32. • SYMPATHETIC CHAIN BLOCKADE WITH
ISB CAN CAUSE BRONCHOSPASM DUE
TO UNOPPOSED VAGAL
PARASYMPATHETIC ACTION

33. • HEAD ROTATION MORE THAN 30
DEGREES DISTORTS THE ANATOMICAL
GROOVE AND VASCULAR RELATIONSHIP
• INTERCOSTOBRACHIAL NERVE TO BE
INFILTRATED FOR ANESTHESIA AROUND
MEDIAL PART OF SHOULDER AND
FOREARM

34. IMPORTANCE OF VARIATION IN
ANATOMY
• No neurostimulation
• Inappropriate neurostimulation
• Appropriate neurostimulation but
inadequate block
• Total block failure

35. The posterior cord is discrete in 25%,in 71%
continues as various nerves and in 4%
directly as the radial nerve.

36. • The upper two roots join to form the upper
trunk, this is C5-6.
• This is exactly the position of the
stimulating needle tip,

37. • The trunks lay above each other with
sparse connective tissue between them.
• Drug injected at the upper trunk will slowly
disperse along a concentration gradient.

38. • The distance between the interscalene
and the subclavian area is too small, drug
injected correctly in the sheath will spread
across the entire length from the cervical
root to the supraclavicular area.

39. • The scalene muscle and the brachial
plexus are in same plan ,thus the needle
should be perpendicular to this plane.

40. PHRENIC NERVE
• The phrenic nerve is in close relation to
the trunks of brachial plexus in the
inrerscalene area.
• It lies on the anterior scalene muscle and
courses from the lateral aspect of scalene
to the medial.

41. • The higher level interscalene block ,the
more the incidence of phrenic nerve block.

42. • Contrast study showed, the spread of contrast is
linear and compressed between the two scalene
muscle and widens lower down at the midpoint of
the clavicle.
• The contrast spreads close to the anterior scalene
muscle thus blocking the phrenic nerve.

43. • Combining low volume LA and digital
pressure was thought to reduce incidence
of phrenic nerve palsy.

44. SUPRASCAPULAR NERVE
• This nerve accompanies the trunks for a
considerable distance and then leaves
posteriorly through the middle scalene
muscle.

45. • Stimulation of the suprascapular nerve is
possible and provides a false feeling of the
needle tip in the sheath of brachial plexus.

46.  One branch arises from the trunks.
Suprascapular nerve, it arises from the
upper trunk and supplies the supraspinatus
and infraspinatus muscles, and sensation to
the glenohumeral and acromioclavicular
joints.

47. SUPRACLAVICULAR BLOCK

50. • BLOCK IS AT THE LEVEL OF DIVISIONS
• BRACHIAL PLEXUS IS SUPPOSED TO
BE COMPACT AT THIS LOCATION,
DENSE ACTION EXPECTED

51. • ANATOMICAL LANDMARK -
SUBCLAVIAN ARTERY ( BP IS
POSTEROLATERAL )
• 0.5 -6 % CHANCES OF
PNEUMOTHORAX
• VASCULAR INJURIES COMMON

52. INFRACLAVICULAR
ANATOMY
• The divisions pass over the first rib close
to the dome of the lung and continue
under the clavicle as cords immediately
posterior to the subclavian artery.
• The sheath is completely stripped off the
infraclavicular cords.

53. • The cords are identified according to their
relationship to the axillary artery.
• The lateral cord lies more laterally and
superficially and is first to be encountered
during an infraclavicular block.

54. • The lateral cord always lies anterior to
either the posterior or medial cord and
cranial to the axillary artery.
• The posterior cord was always cranial to
the medial cord and both cords were
always located dorsal to the artery.

55. • There are at least 13 branches at infraclavicular
area.
• The musculocutaneous nerve has an anomalous
origin or connection to the median nerve in
11%,and a connection carrying C7 fibers from the
lateral cord to the ulnar nerve occurs in 42% of
anatomic specimens

56. • The lateral root of the median nerve may
pass posterior to the axillary artery and the
axillary and radial nerves may arises
directly from the division such that a true
posterior cord is not present.

57. • The musculocutaneous nerve (MCN)
leaves the brachial plexus sheath high in
the axilla at the level of the lower border of
the teres major muscle and passes into
the substances of coracobrachialis
muscle.

58. • The MCN exits out of the lateral cord early
in the course and is reliably blocked in
infraclavicular area.

59. AXILLARY BLOCK

60. • BLOCK GIVEN AT THE LEVEL OF
CORDS
• ANATOMICAL LANDMARK – AXILLARY
ARTERY
• CORDS SURROUND THE ARTERY IN
2’O CLOCK TO 11’O CLOCK POSITION

61. • VASCULAR INJURIES VERY COMMON
• TOO MEDIALLY DIRECTED NEEDLE
INCREASE THE CHANCE OF
PNEUMOTHORAX

62. • TARGETTING POSTERIOR CORD
STIMULATION GIVES EQUAL SPREAD
TO ALL THE CORDS
• FINGER/WRIST – FLEXION /
EXTENSION AS END POINT OF
NEUROSTIMULATION

63. • BICEPS CONTRACTION SUGGESTIVE
OF MUSCULOCUTANEOUS…DO NOT
ACCEPT AS THIS NERVE EXITS THE
PLEXUS BEFOREHAND
• TOURNIQUET PAIN POSSIBLE WITH
PLAIN AXILLARY BLOCK

64. AXILLARY NERVE
• It supplies the shoulder joint, the surgical
neck of humurus, the deltoid, and the teres
minor muscle before ending as the
superior lateral brachial cutaneous nerve,
which innervates the superolateral part of
proximal arm.

65. AXILARY AREA DISSECTION

66. My sincere thanks to
Dr. Avadhoot Kulkarni

67. THANK YOU