Lesson-Interscalene

8 – Indications of the interscalene block

The indications of the interscalene block are:

– Anaesthesia for shoulder surgery & shoulder
procedures

– Analgesia after shoulder surgery & shoulder
procedures

The ultrasound guided interscalene brachial plexus block is a basic level block

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A dislocated shoulder joint can be reduced using an interscalene brachial plexus block

9 – How to perform an ultrasound guided interscalene brachial plexus block

– Select a high-frequency linear probe
– Adjust gain, focus, and depth 2-3 cm
– Turn the orientation mark on the probe postero-lateral on the right side and antero-lateral on
the left side of the patient
– Place the probe behind the clavicle on top of the first rib oriented practically in the
parasagittal plane
– Locate the black, pulsatile subclavian artery (SA) on top of the first rib between the anterior
and the middle scalene muscles
– Locate the branches of the brachial plexus (BP) posterior to the SA
– Track the BP branches proximally until the profiles of the C5 and C6 spinal nerve roots line
up like a string of black pearls in the interscalene groove. C5 appears as one profile, C6 as
two
– Capture the best possible cross sectional image by tilting the probe and fine-tuning gain,
focus, and depth

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(A) Starting position (B) subclavian artery (A), costa I (CI) and brachial plexus branches (PB) (C) Track the brachial plexus branches proximally (D) C5 and C6 spinal nerve branches into the intescalene groove where they are sandwiched between the anterior scalene (SA) and the middle scalene (SM)

1 – Anatomy of the brachial plexus

The brachial plexus (BP) innervates the upper limb

The BP originates from five spinal nerve roots: C5 to T1

The shoulder is innervated by the suprascapular nerve and the axillary nerve. They both originate from the spinal nerve roots C5 and C6

Anaesthesia of the shoulder requires blockade of the BP proximal to the level of the trunks, because the suprascapular nerve branches off the superior trunk

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The brachial plexus is displayed with the suprascapular nerve (red arrow) and the axillary nerve (blue arrow). The five spinal nerve roots of the brachial plexus are indicated by C5 to T1. Green asterix = superior trunk; red asterix = middle trunk; blue asterix = inferior trunk.

2 – The bone innervation of the shoulder

The shoulder and the shoulder joint is innervated by the axillary nerve and the suprascapular nerve

Minor contributions from the long thoracic nerve and capsular filaments from the infraspinatus nerve are not clinically significant

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The figure shows the bony structures of the shoulder from an anterior and a posterior view. The axillary nerve innervates the anterior side (purple). The suprascapular nerve innervates the posterior side (“bone” color). The blue color is innervated by the radial nerve.