brachial plexus

1. BRACHIAL PLEXUS
ITS ANATOMY
AND BLOCK
DR ZIKRLLAH

3. ANATOMY
 The brachial plexus is formed by the union
of the anterior primary divisions (ventral
rami) of the fifth through eighth cervical
nerves ( C5,C6,C7,C8 ) and first thoracic
(T1) nerve, with variable contributions
from C4 and T2.
 It consists of roots, trunks, divisions, cords
and terminal branches.

5.  The roots of the plexus (anterior primary
rami of C5-T1 nerves) are between the
scalene muscles, the trunks in the
posterior triangle, the divisions behind the
clavicle, and the cords arranged around
the second part of axillary artery.
 About 10% of plexuses are prefixed (from
C4-C8) and 10% postfixed (from C6-T2).

6. COURSE
The nerves roots leave the intervertebral
foramina and course anterolaterally and
inferiorly to lie between the anterior and
middle scalene muscles.
Between these muscles, these nerve roots
unite to form 3 vertically arranged trunks-
upper(C5,C6), middle(C7), lower(C8,T1).

7.  The prevertebral fascia invests the
anterior and middle scalene muscles and
fuses laterally to enclose the brachial
plexus in a fascial sheath.
 The trunks emerge from the interscalene
space to lie cephaloposterior to the
subclavian artery as it courses along the
upper surface of the first rib.

8.  As the trunks pass over the lateral border of the
first rib and under the clavicle, each divides into
anterior and posterior divisions.
 The divisions pass posterior to the middle of the
clavicle to enter the axilla, surrounded by the
fascial sheath descended from the prevertebral
fascia.
 Here they combine again to form three cords
which are named according to their relationship
to the second part of axillary artery.

9.  Lateral cord- formed by the union of
anterior divisions of superior and middle
trunks.
 Medial cord- formed by the anterior
division of inferior trunk.
 Posterior cord- formed by the posterior
divisions of all three trunks.

11.  At the lateral border of pectoralis minor each
cord divides into the peripheral nerves of the
upper extremity.
 Lateral cord- gives off lateral branch of Median
nerve; terminates as Musculocutaneous nerve.
 Medial nerve- gives off medial branch of Median
nerve and median cutaneous nerves of arm and
forearm; terminates as Ulnar nerve.
 Posterior nerve- gives off Axillary nerve;
terminates as Radial nerve.

12.  Anterior scalene muscle: arises from
the anterior tubercles of transverse
processes of the third , fourth, fifth and
sixth cervical vertebrae and is inserted
into the scalene tubercle on the inner
border of the first rib.
 The muscle lies anterior to the brachial
plexus, being seperated from it below by
the subclavian artery.
 Its lateral border, if palpable, is a guide to
the position of the plexus.

13.  Medial scalene muscle: arises from the
posterior tubercles of the six lowest
cervical vertebrae, and is inserted into the
upper surface of the first rib behind the
groove made by the brachial plexus and
the subclavian artery. The plexus thus lies
in front of the muscle.

14.  First rib: the first rib lies in an almost
horizontal plane, being inclined slightly
downwards and forwards.
 It passes below the clavicle at about the
junction of its inner and middle thirds.
 Head: the head has a single articular
facet, which articulates with the body of
the first thoracic vertebra.
 Tubercle: the tubercle articulates with the
transverse process of the same vertebra.

15.  Upper surface: it has two articular
grooves- an anterior one for the
subclavian vein and a posterior one for the
subclavian artery and the lowest trunk of
the brachial plexus. On the inner border,
between the grooves, is the scalene
tubercle.
 The subclavius muscle arises in front of
the anterior groove and the scalenus
medius is inserted behind the posterior
groove.

16.  Lower surface: the lower surface of the first rib
has no costal groove- the inner border embraces
the dome of the pleura and the outer border
gives origin to the first slip of the serratus
anterior.
 Subclavian artery: the subclavian artery
extends from its origin to the outer border of the
first rib. The right subclavian artery originates
from the innominate artery and the left from the
aortic arch.

17.  A major portion of the brachial plexus is located
parallel and lateral to the third part of the
subclavian and first part of the axillary artery,
just above and below the clavicle, respectively.
 The third part of the subclavian artery extends
from the outer border of the anterior scalene
muscle laterally and caudally to the outer border
of the first rib, where it becomes the first part of
the axillary artery.

18.  The terminal part of the subclavian artery
lies behind the clavicle near its midpoint.
At this level the inferior trunk of the
brachial plexus is posterior to the third
part of the third part of the subclavian
artery. The upper two trunks of the
brachial plexus lie superior and lateral to
the subclavian artery.

19.  Subclavian vein: the subclavian vein is
separated from the brachial plexus by the
anterior scalene muscle. As it is well protected
by the clavicle, it is unlikely to be punctured.
 The brachial line: the brachial line runs in a
straight line from the transverse process of the
sixth cervical vertebra to the axillary artery in
the axilla. It runs inferolateral at 45 degrees
from the horizontal and slightly forwards at 15
degrees.

20. Branches of brachial plexus
 Branches of the roots:
 C5- dorsal scapular
 C5,6- nerve to subclavius
 C5,6,7- long thoracic nerve
The dorsal scapular nerve (C5) runs down
deep to levator scapulae and the two
rhomboids, supplying all three muscles.

21.  Lying on serratus posterior superior, it forms
neurovascular bundle with the descending
scapular vessels alongside the vertebral border
of the scapula
 The nerve to subclavius (C5,6) passes down
over the trunks of the plexus and in front of the
subclavian vein. It frequently contains contains
accessory phrenic fibres which join the phrenic
nerve in the superior mediastinum.

22.  The long thoracic nerve (C5,6,7) ,forms on
the first digitation of the serratus anterior
muscle and runs vertically downwards just
behind the midaxillary line, deep to the
fascia over the muscle.

23.  Branches of the upper trunk:
 The supraclavicular nerve (C5,6), prominent
beneath the fascial floor of the posterior
triangle, passes beneath the transverse scapular
ligament and round the lateral border of the
scapular spine. The nerve supplies
supraspinatus, infraspinatous, and the shoulder
and acromioclavicular joints.

24.  Branches of the lateral cord:
 C5,6,7- lateral pectoral
 C5,6,7- musculocutaneous
 C5,6,7- lateral root of median
 The lateral pectoral nerve (C5,6,7) passes
through the clavipectoral fascia and
supplies the upper fibres of the pectoralis
major.

25.  It also contributes to the supply of pectoralis
minor via a communicating branch.
 The musculocutaneous nerve (C5,6,7) supplies
the flexors of the arm- coracobrachialis, biceps
brachii and brachialis.
Below the elbow, it is known as the ‘ lateral
cutaneous nerve of the forearm’ and gives the
cutaneous supply from elbow to wrist by an

26. anterior and a posterior branch along the
radial border of the forearm.
 The lateral root of the median nerve
(C5,6,7) is joined by the medial root to
form the main nerve.

27.  Branches of the medial cord:
 C8,T1- medial pectoral
 C8,T1- medial root of median
 C8,T1- medial cutaneous nerve of arm
 C8,T1- medial cutaneous nerve of forearm
 C8,T1- ulnar
 The medial pectoral nerve gives a branch to

28. pectoralis minor and then pierces it to
supply the sternocostal fibres of the
pectoralis major.
 The medial root of the median nerve
crosses the axillary artery to join its
companion and form the median nerve at
the lateral side of the artery.

29.  The median cutaneous nerve of arm is the
smallest branch of the plexus. It supplies
the skin on the medial aspect of the arm.
 The medial cutaneous nerve of the
forearm supplies the skin over the lower
part of the arm and the medial side of the
forearm.

30.  The ulnar nerve is the largest branch of
the medial cord and supplies most of the
small muscles of the hand.
 Branches of the posterior cord:
 C5,6- upper subscapular
 C6,7,8- thoracodorsal
 C5,6- lower subscapular

31.  C5,6- axillary
 C5,6,7,8,T1- radial
 The upper and lower subscapular nerves
supply the respective parts of the
subscapularis, with the lower nerve also
supplying teres major.

32.  The thoracodorsal nerve supplies the
latissimus dorsi. It is thrown into
prominence in the position of lateral
rotation and abduction of the humerus
and is thus in danger in surgeries on the
lower axilla.

33.  The axillary nerve divides into anterior and
posterior branches after supplying the
shoulder joint. The anterior branch
supplies the deltoid and a small area of
overlying skin. The posterior branch
supplies the teres minor and deltoid, and
continues as the ‘upper lateral cutaneous
nerve of the arm’.

34.  The radial nerve is the continuation of the
posterior cord and is the largest branch of
the brachial plexus.
 In the arm, it supplies the triceps and the
skin along the posterior surface (‘posterior
cutaneous nerve of the arm).

35. TECHNIQUES OF BRACHIAL BLOCK
The fascial sheath derived from the prevertebral
and scalene fascia which encloses the brachial
plexus extends from the intervertebral foramina
to the upper arm. It serves as the anatomic
basis for brachial blocks.
Injection into this sheath allows local anaesthetic
to spread and block C5-T1 nerve roots. The
degree of neural blockade however, may vary
depending on the level of injection.

36. 1. INTERSCALENE APPROACH
 Anatomy: the cervical nerves form the upper, middle and
lower trunks between the anterior and middle scalene
muscles. The interscalene groove lies at the level of
cricoid cartilage; it is an easy place to enter the brachial
sheath.
 Indications: major indication is shoulder surgery, as
blockade is most intense at the level of upper and
middle trunks (C5-C7).
Blockade of inferior trunk is often incomplete; hence it
may be used for forearm and hand surgery after
supplementing Ulnar nerve blockade.

39.  Technique:
 Patient is placed in supine position with head
turned slightly to the contralateral side.
 Posterior border of sternocleidomastoid is
palpated by having the patient briefly lift his
head.
 Interscalene groove is palpated by rolling the
fingers posterolaterally from this border over the
belly of the anterior scalene muscle into the
groove.

41.  A line is extended laterally from the cricoid
cartilage to intersect the interscalene
groove indicating the level of transverse
process of C6 vertebra.
 Under sterile precautions local anaesthetic
is injected at this point and a skin wheal is
raised.

43.  A 22-25 G, 4 cm needle is introduced
perpendicular to the skin and advanced in
slightly medial and caudal direction until a
paraesthesia or evoked muscle contraction in
arm is elicited.( when a blunt bevelled needle is
used a ‘click’ may be detected as it passes
through the prevertebral fascia)
# if bone is encountered within 2 cm of skin, it is
likely to be a transverse process and the needle
may be ‘walked’ across this structure to locate
the nerve.
# contraction of the diaphragm indicates phrenic
nerve stimulation and anterior placement of
needle. It should be redirected posteriorly to
locate the brachial plexus.

44. #stimulation of the trapezius muscle indicates the
needle may be too ‘posterior’.
After appropriate paraesthesia or motor response
is obtained, the needle is stabilised. After
negative aspiration, 10-40 ml of solution is
injected.
Digital pressure above the injection site and
downward massage along with a 45 degree
head up position may facilitate caudal spread
and blockade of the lower trunk.

46.  This was the initial technique for brachial block,
described by WINNIE in 1970.
 This approach was later modified by MEIER.
 In this modification, the puncture point is at the
posterior edge of sternocleidomastoid, but
located 2-3 cm more cranially at the level of the
superior thyroid notch.
 The needle is directed caudally at 30 degrees to
the skin and slightly lateral, aiming for the mid
to lateral point of clavicle.

47.  This approach is recommended for
interscalene catheter insertion, and it also
avoids inadvertent injection into the
vertebral artery, epidural space or CSF.

49. Modified lateral approach of
BORGEAT
 The insertion point is same as Winnie
approach,i.e. in the interscalene groove,
just behind sternocleidomastoid at the
level of cricoid cartilage, but the needle is
directed along the interscalene space,
towards the posterior part of the superior
or middle trunk (in order to elicit triceps
contraction).

50. CERVICAL/POSTERIOR
APPROACHES
 KAPPIS / PIPPA Approach
 Advantages: needle passes only through
muscle and not nerves/arteries.
 Head is flexed maximally and the spinous
processes of C6 and C7 are palpated.
 A horizontal line of 3 cm is drawn laterally,
midway between C6 and C7 vertebrae.

51.  After connecting a nerve stimulator, a 10 cm
insulated needle is inserted in a sagittal plane (
aiming for the cricoid cartilage).
 Contact is made with the transverse process of
C7 vertebra after 5-6 cm.
 The needle is then redirected more cranially and
brachial plexus is located after 6-8 cm.( this is
confirmed by muscle contractions of the
shoulder or abduction of arm, corresponding to
upper trunk stimulation.)

52. BOEZAART Approach
 Start at the level of the first costovertebral angle
and insert the needle into the V-shaped groove
between the anterolateral edge of trapezius and
the posteromedial edge of levator scapulae;
aiming 45 degrees from a parasagittal plane and
30 degrees caudal towards the sternal notch.
 Once the transverse process of C6 vertebra is
identified, the needle is repositioned, aiming
anteriorly and using a loss of resistance
technique.

53. complications
 Ipsilateral phrenic nerve palsy – diaphragmatic
blockade.
 Horner’s syndrome
 Hoarseness of voice
 Seizures
 CNS toxicity
 Epidural, subarachnoid, subdural injection
 pneumothorax

54. 2. SUPRACLAVICULAR APPROACH
 Anatomy: At the lateral border of the anterior
scalene muscle, the brachial plexus passes down
between the first rib and clavicle to enter the
axilla. The trunks are clustered vertically over
the first rib cephaloposterior to the subclavian
artery. The neurovascular bundle lies inferior to
the clavicle at about its midpoint. The first rib
acts as a medial barrier to the needle’s reaching
the pleural dome.

55.  Clinical applications: indicated for
operations on the elbow, forearm and
arm.
-blockade occurs at the level of distal
trunks and proximal divisions
-the brachial plexus is compact at this
point and a small volume of solution
produces rapid onset of reliable blockade.

56.  Technique:
 Patient is placed supine with head turned
towards the contralateral side.
 Midpoint of the clavicle should be identified and
marked.
 The posterior border of sternocleidomastoid can
be easily palpated by asking the patient to raise
his head slightly.
 The palpating fingers must be then rolled over
the belly of the anterior scalene muscle, into the
interscalene groove, where a mark should be
made approx. 1.5-2.0 cm posterior to the
midpoint of the clavicle.

57.  Palpation of the subclavian artery at this site
confirms the landmark.
 After raising a skin wheal of LA at this site, a 22-
G, 4 cm needle is directed in a caudal, slightly
medial and posterior direction till a paraesthesia
or motor response is elicited or the 1st rib is
encountered.
 # If rib is encountered without elicitation of
paraesthesia, the needle can be systematically
‘walked’ anteriorly or posteriorly along the rib.

58.  #If the artery is located, the needle can be
withdrawn and reinserted in a more
posterolateral direction.
 On localization of the plexus, aspiration for blood
should be performed before incremental
injections of a total volume of 20-30 ml of the
solution.
This was the classic supraclavicular approach
of Kulencampff.

63.  Two other supraclavicular approaches
have been mentioned:
 1) the subclavian perivascular approach
of Winnie and Collins- the subclavian
artery is palpated immediately lateral to
the clavicular head of sternocleidomastoid
at the level of the cricoid cartilage (C6
vertebra). A 3-4 cm needle is inserted
behind the subclavian artery and after
paraesthesia, 40 ml of LA is injected.

64.  2) The Modified lateral paravascular approach of
Moorthy: positioning is the same as for classic
aprroach. The course of subclavian artery from
above to below the clavicle and into the axilla is
marked. The needle is advanced along and
parallel to the surface marking of subclavian
artery, caudally, laterally and posteriorly, the tip
of needle being directed towards the axilla and
away from the pleura, medial and inferior to the
subclavian artery.

65.  Complications:
 High incidence of pneumothorax (0.5-6%)
 Horner’s syndrome
 Phrenic nerve block
 Neuropathy

66. 3. INFRACLAVICULAR BLOCK
 Anatomy: after entering the axilla, the trunks
divide into anterior and posterior divisions each
and then reform into lateral, medial and
posterior cords.
 The infraclavicular approach blocks the brachial
plexus at the level of the cords.
 Clinical applications: provides homogenous
anaesthesia to the brachial plexus and can be
used for procedures involving arm, elbow,
forearm and hand.

69.  Technique: All infraclavicular techniques place LA
below the clavicle but on a line passing from the
neck,under the clavicle and into the axilla.
 1) Classic approach- Patient lies supine with head
turned slightly towards the contralateral side.
Operative limb is abducted to 90 degrees and
axillary pulse identified.
 Midpoint of the clavicle is identified and a needle is

70. inserted 2 cm caudal to this point at an angle of
45 degrees towards axillary artery pulsation.
 A nerve stimulator is used to identify the plexus
and motor activity in the hand is sought.
 Once identified, the stimulation is decreased to
<0.5 mA and fade of motor activity is witnessed
after injection of 1-2 ml of LA.
 Then after negative aspiration of blood, 30-40
ml of LA is injected.

73.  2) Coracoid technique:
 With patient’s arm in any position, the
coracoid process is identified and marked.
 2 cm medial and 2 cm caudal from the
coracoid process, the needle is inserted
perpendicular to the skin till motor
response is achieved with the nerve
stimulator.

75.  Stimulation is decreased to <0.5 mA and after
injecting 1 ml of LA , fade in motor activity is
witnessed.
 Then 30-40 ml of LA is injected after negative
aspiration of blood.
 3) vertical infraclavicular approach:
 This method is based on measurements from
cadaver dissection.

76.  Studies on cadavers have shown that the
brachial plexus lies at a max. depth of 4
cm and lateral to the axillary artery and
vein, where the three cords converge at
the entrance to the trigonum of the
clavipectoral fascia. This corresponds to a
skin puncture point corresponding to the
midpoint between the ventral apophysis of
the acromian and the jugular notch
(infraclavicular line).

77.  Ventral apophysis is identified by following the
scapula laterally to the acromian and then
ventrally.
 The correct ventral position is confirmed when
the anaesthetist’s fingers remain static during
movement of the shoulder joint.
 At the calculated midpoint the needle is inserted
vertically.
 The advantages of VIB are that it is simple to
learn, has a high success rate, tourniquets are
easily tolerated, patients are comfortably
positioned and catheter insertion is simple.

78.  Complications:
 Pneumothorax, hemothorax and
chylothorax (in left sided blocks) may
occur.
 Contraindications: this technique is not
indicated if there’s an infection in the skin,
chest wall or axilla.

79. 4. AXILLARY BLOCK
 The axillary brachial block was first
described by Halstead in 1884.
 Advantages: a) presence of a single
landmark ( the axillary artery)
b) no possibility of pneumothorax,
stellate ganglion block, recurrent laryngeal
nerve block, phrenic nerve block.

80. Anatomy: subclavian artery continues as the
axillary artery in the axilla i.e. beneath the
clavicle.
At the lateral border of pectoralis minor, the
cords form large terminal branches.
The fascial sheath is multicompartmental
and these fascial septa may result in
incomplete spread of LA within the plexus
sheath leading to ‘patchy’ anaesthesia in
many patients.

81.  Clinical applications:
 This approach tends to produce the most
intense block in the distribution of C7-T1 but is
usually inadequate for procedures on the
shoulder and upper arm(C5-C6).
 Indicated for surgeries on elbow, forearm and
hand.
 Unsuitable for surgeries on upper arm and
shoulder.

82.  Techniques:
 Axillary block is performed by one of the
several techniques that use the axillary
arterial pulse as the landmark.
 Patient positioning: The patient is placed
supine with the arm abducted, the elbow
flexed at 90 degrees, and externally
rotated at the shoulder leaving the arm
lying across the patient’s head.

85.  1) Transarterial technique:
 The pulse of the axillary artery is identified
as proximal in the axilla as possible.
 Once the artery is identified, it should be
stradalled between the index and middle
fingers and held tightly against the
humerus to prevent it from ‘rolling’.
 Then, a 22 G, 4 cm needle is inserted until
bright red blood is aspirated.
 The needle is then slightly advanced or
withdrawn until blood aspiration ceases.

87.  Injection can be performed anteriorly,
posteriorly, or in both locations in relation
to the axillary artery. A total of 40 ml of
LA is usually injected.
 2) Elicitation of paraesthesia technique:
 With this technique, the needle is directed
towards the axillary artery to elicit a single
or multiple paraesthesias.

88.  If the artery is entered, the needle is
redirected until a paraesthesia is obtained.
 Paraesthesia may be elicited in any area
within brachial plexus distribution or
separately in ulnar, median and radial
nerve distribution.
 40 ml of the LA is injected.

89.  3) Nerve stimulator technique: For this
technique, it is important to understand
the relationship of the three nerves to be
blocked with the axillary artery.
 In the axilla, branches of the brachial
plexus envelope the axillary artery. As the
three main nerves (median, ulnar, radial)
begin to move apart from each other
shortly after passing the lateral border of
the pectoralis minor, a better block is
obtained with a more proximal approach.

90.  The axillary artery is ‘pinned’ in a stable
position. Each finger is placed parallel with
the artery.
 Using a nerve stimulator, a 2-in, 22-G
insulated stimulating needle is inserted
proximal to the operator’s fingers and
appropriate muscle twitches in the hand
are sought.
 Once identified, the stimulation is reduced
to

91. <0.5. fading of the motor activity is
observed after injection of 1 ml of LA.
 Then after negative aspiration of blood,40
ml of local anaesthetic is injected.
 Complications: the axillary approach is
associated with a very low complication
rate, provided intravascular injection is
avoided.

92. CONTINUOUS INFUSION
 Continuous infusion of local anaesthetic
can be used to prolong neural blockade
without the tachyphylaxis seen in
repeated bolus techniques.
 The infraclavicular approach lends itself to
continuous infusion because the catheter
is easily fixed to the pectoral region.

93.  This is particularly useful following
reimplantation procedures or other
vascular injuries resulting in vasospasm.
The prolonged sympathectomy provided
permits improved blood flow to the area of
injury.

95.  The infraclavicular approach lends itself to
continuous infusion because the catheter is
easily fixed to the pectoral region.
 Maintaining postoperative pain with
infraclavicular catheters is best served with a
combination of background infusion and patient
controlled boluses.
 This also decreases the requirement for
postoperative opioids and opioid related side
effects.
 Reliance on either constant infusion or boluses
alone is associated with more breakthrough pain
and less patient satisfaction.

96. THANK YOU