US Guided Regional Anesthesia

3 – Supraspinatus and infraspinatus muscles

The supraspinatus muscle is located in the supraspinous fossa above the scapular spine, and the infraspinatus muscle is located in the infraspinous fossa below the scapular spine

The supra- and infraspinatus muscles are innervated by the suprascapular nerve; they are lateral rotators of the shoulder joint and initiators of shoulder abduction

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Supraspinatus muscle (yellow asterix), infraspinatus muscle (green asterix), suprascapular nerve (green arrow), suprascapular artery (blue arrows), axillary nerve (magenta arrows), scapular spine (cyan arrow)

6 – The supraclavicular approach to block the suprascapular nerve ultrasound-guided

Place the patient supine with the head turned contralateral

Place a high-frequency linear probe in the axial plane visualizing the transverse process of C6 with its prominent anterior tubercle (Chassaignac’s tubercle); check that the transverse process of C7 has no anterior tubercle to validate the correct level

Move the probe cranial and identify the C5 nerve root between the anterior and posterior tubercles of the transverse process of C5; follow the C5 nerve root peripherally until it fuses with the C6 nerve root and becomes the superior trunk

Visualize the suprascapular nerve as it branches off postero-laterally from the proximal part of the superior trunk and dives under the omohyoid muscle (see next page)

Insert the needle in-plane from the posterior/lateral end of the probe and inject 5 mL of local anaesthetic perineurally

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Visualization of the suprascapular nerve with the supraclavicular approach

4 – The suprascapular nerve in the supraclavicular region

The supraclavicular nerve branches off the superior trunk of the brachial plexus and runs in a latero-dorsal direction and crosses underneath the omohyoid muscle

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Suprascapular nerve (green arrow), omohyoid muscle (magenta arrow), superior trunk of the brachial plexus (cyan arrow), trapezius muscle (blue arrow)

7 – Sonoanatomy: Supraclavicular approach to block the suprascapular nerve

The suprascapular nerve is anaesthetized deep to the omohyoid muscle with ultrasound-guidance

The suprascapular nerve runs relatively close to the divisions of the brachial plexus in this location implying a risk of medial spread of local anaesthetic to the brachial plexus

Ref: Siegenthaler et al. (2012)

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Suprascapular nerve (red arrow), omohyoid muscle (magenta asterix), supraclavicular divisions of the brachial plexus (green arrows), L = lateral, M = medial

3 – The axial anatomy of the deep cervical plexus block

At the level of the transverse process of vertebral body C6, both the anterior and middle scalene muscles are prominent, while the capitis longus muscle is inconspicous and located just lateral to the colli longus muscle

The anterior scalene muscle is attached to the anterior tubercles and the middle scalene muscle to the posterior tubercles of the transverse processes

At the level of the transverse process of vertebral body C4, the anterior scalene muscle has tapered while the cross section of the capitis longus muscle has become more prominent; the sympathetic trunk runs anterior to the capitis longus muscle

The picture on the right shows an axial view at the level of vertebral body C6 with the C5 and C6 cervical spinal nerve roots (magenta and green dots in upper picture) and C4 with the C3 and C4 roots (white and yellow dots in lower picture)

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Transverse process (green asterix), m. capitis longus (black asterix), m. colli longus (cyan asterix), anterior and middle scalene mm. (magenta and blue asterixs), cervical sympathetic chain (black arrow), prevertebral fascia (cyan arrow), carotid sheath (white asterix), sternocleidomastoid m. (yellow asterix)

1 – Indications

The suprascapular block is indicated for postoperative analgesia after shoulder surgery when interscalene brachial plexus block is contraindicated

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2 – Anatomy of the suprascapular nerve

The suprascapular nerve origins from the superior trunk of the brachial plexus

It runs under the superior transverse scapular ligament and innervates the supraspinatus and infraspinatus muscles

The superior transverse scapular ligament creates a bridge across the scapular notch and converts the notch to an aperture

The suprascapular nerve runs below the ligament

The suprascapular artery and vein pass superior across the ligament

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Suprascapular nerve (magenta arrows), superior trunk of the brachial plexus (blue arrow), superior transverse scapular ligament (green arrow)

2 – Anatomy of the deep cervical plexus

The deep cervical plexus is sandwiched between the upper part of the medial scalene muscle and the longus capitis muscle and it consists of:

– Ansa cervicalis – a cervical plexus loop with a superior and an inferior root.
The superior root is a branch of the C1 ventral ramus. It briefly joins the hypoglossal nerve.
The inferior root is derived from branches of the C2 ventral rami.

The superior root descends on the carotid sheath. It innervates the superior belly of the omohyoid muscle and the upper parts of the sternothyroid and sternohyoid muscles before it unites with the inferior root. The inferior root of the ansa cervicalis is derived from branches of the C2 and C3 ventral rami. It innervates the inferior belly of the omohyoid muscle and the inferior parts of the sternothyroid and sternohyoid muscles.

– Phrenic nerve from C3-C5 innervates the diaphragm and the pericardium
– Branches from C1-C4 innervate the anterior and middle scalene muscles

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Phrenic nerve (black arrow), superior and inferior roots of the ansa cervicalis (cyan and white arrows), middle scalene muscle (green arrow), longus capitis muscle (magenta arrows), longus colli muscle (blue arrow).

4 – Ultrasound guided needle insertion for deep cervical plexus block

Place the probe in the axial plane at the level of the transverse proces of vertebral body C4

The needle is advanced with in-plane technique from the posterior end of the probe until it penetrates the prevertebral fascia and the needle tip is placed just posterior to the longus capitis muscle

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Transverse process of vertebral body C4 (green asterix), longus capitis m. (yellow asterix), middle scalene m. (magenta asterix), longus colli m. (blue asterix), carotid sheath (yellow arrow), prevertebral fascia (cyan arrow), needle trajectory (magenta arrow), sternocleidomastoid m. (red asterix)

1 – Indications for the ultrasound guided deep cervical plexus block

A deep cervical plexus block blocks both the deep and superficial branches of the cervical plexus. It is a paravertebral block of the spinal nerve roots C2-C4

The indications are:

– carotid endarterectomy

– excision of cervical lymph nodes

The deep cervical plexus block anaesthetises both the sensory and the motor nerve branches of the cervical plexus, while the superficial cervical plexus block anaesthetises the sensory branches solely

Because the sensory blockade is equivalent for superficial and deep cervical plexus blocks, and because the deep block is more risky, the superficial cervical plexus block is generally favoured compared to the deep cervical plexus block

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Ultrasound guided blockade of the deep cervical plexus