- Email: [email protected]
The cervical plexus
VASCULAR ANAESTHESIA
The cervical plexus
Learning objectives
Marco L Baroni After reading this article you should be able to:
David C Berridge
C C C
Abstract A knowledge of the cervical plexus and the posterior triangle of the neck is important when performing a cervical plexus block. This useful regional anaesthetic technique can be utilized in carotid, ear, nose and throat (ENT) and thyroid surgery. In this article we revise the relevant anatomy and clinical application.
define the boundaries of the posterior triangle of the neck list the nerve roots which form the cervical plexus outline the contribution of the cervical plexus to the sensory and motor innervation of the neck.
the lesser occipital nerve (C2) supplying the skin over the upper part of sternocleidomastoid and posterior to the ear the greater auricular nerve (C2) supplying the skin of the ear, over the mastoid and up to the angle of the mandible the transverse cervical nerve (C2, C3) supplies the midline of the neck throughout its length the supraclavicular nerve (C4) supplies a large area over the lateral neck and onto the upper thorax and shoulder. Superficial cervical plexus block, with or without deep plexus block is an important part of local anaesthesia for carotid endarterectomy, and can be useful in thyroid, neck and ear surgery. The superficial plexus is blocked by infiltrating along the posterior border of sternocleidomastoid, fanning out from a hypothetical point level with the cricoid cartilage. Deep plexus block is best performed either under ultrasound guidance or with the assistance of a nerve stimulator, aiming to stimulate scalenus medius. Bilateral deep block should be avoided, as there is a risk of bilateral phrenic nerve or recurrent laryngeal nerve palsy. Likewise care should be taken if there is a known contralateral phrenic nerve palsy. Inadvertent brachial plexus block is another noteworthy potential complication. A
Keywords Carotid endarterectomy; cervical plexus; cervical plexus block; posterior triangle; regional anaesthesia
The cervical plexus lies on scalenus medius and is formed from the upper four cervical nerves. It has both sensory and motor components, its cutaneous branches supplying the front and the side of the neck. Cervical plexus block is an important regional anaesthetic technique. Knowledge of the posterior triangle is essential in performing a cervical plexus block. The posterior triangle of the neck is formed by the posterior border of sternocleidomastoid anteriorly and trapezius posteriorly, its base being the middle third of the clavicle. The roof of the posterior triangle is the deep cervical fascia and the floor is the prevertebral fascia which overlies the scalene muscles (see Figure 1). The cervical plexus does not lie within the posterior triangle as it is deep to the prevertebral fascia and partially covered by the upper part of the sternocleidomastoid muscle. The cutaneous branches of the cervical plexus pierce the fascia at the posterior border of sternocleidomastoid and do lie within the posterior triangle. The cervical plexus is formed from the anterior rami of C1, C2, C3 and C4, proximal to the brachial plexus. There is a segmental muscular supply to the prevertebral muscles, and branches from C1, C2 and C3 to ansa cervicalis to supply the infrahyoid muscles and thyrohyoid. The motor supply to trapezius and sternocleidomastoid is via the accessory nerve. However, occasionally there are some contributory motor fibres from C3 and C4 to trapezius. The phrenic nerve supplying the diaphragm is predominantly formed from C4. However, there is a small contribution from C3 and C4 (hence the traditional rhyme ‘C3, 4, 5 keep the diaphragm alive’). Cutaneous branches of the cervical plexus (from superior to inferior) are as follows:
Great auricular nerve
Parotid gland
Lesser occipital nerve
Trapezius Sternocleidomastoid
Accessory nerve
Transverse cervical nerve Supraclavicular nerves C3 and C4 to trapezius Omohyoid Transverse cervical artery
Figure 1 Right posterior triangle.
Marco L Baroni FRCS (Gen Surg) is a Consultant Vascular Surgeon at York Hospital, York, UK. Conflicts of interest: none declared. David C Berridge DM FRCS (Eng) (Ed) is a Consultant Vascular Surgeon at Leeds General Infirmary, Leeds, UK. Conflicts of interest: none declared.
ANAESTHESIA AND INTENSIVE CARE MEDICINE 11:5
201
Ó 2010 Elsevier Ltd. All rights reserved.
The cervical plexus
Learning objectives
Marco L Baroni After reading this article you should be able to:
David C Berridge
C C C
Abstract A knowledge of the cervical plexus and the posterior triangle of the neck is important when performing a cervical plexus block. This useful regional anaesthetic technique can be utilized in carotid, ear, nose and throat (ENT) and thyroid surgery. In this article we revise the relevant anatomy and clinical application.
define the boundaries of the posterior triangle of the neck list the nerve roots which form the cervical plexus outline the contribution of the cervical plexus to the sensory and motor innervation of the neck.
the lesser occipital nerve (C2) supplying the skin over the upper part of sternocleidomastoid and posterior to the ear the greater auricular nerve (C2) supplying the skin of the ear, over the mastoid and up to the angle of the mandible the transverse cervical nerve (C2, C3) supplies the midline of the neck throughout its length the supraclavicular nerve (C4) supplies a large area over the lateral neck and onto the upper thorax and shoulder. Superficial cervical plexus block, with or without deep plexus block is an important part of local anaesthesia for carotid endarterectomy, and can be useful in thyroid, neck and ear surgery. The superficial plexus is blocked by infiltrating along the posterior border of sternocleidomastoid, fanning out from a hypothetical point level with the cricoid cartilage. Deep plexus block is best performed either under ultrasound guidance or with the assistance of a nerve stimulator, aiming to stimulate scalenus medius. Bilateral deep block should be avoided, as there is a risk of bilateral phrenic nerve or recurrent laryngeal nerve palsy. Likewise care should be taken if there is a known contralateral phrenic nerve palsy. Inadvertent brachial plexus block is another noteworthy potential complication. A
Keywords Carotid endarterectomy; cervical plexus; cervical plexus block; posterior triangle; regional anaesthesia
The cervical plexus lies on scalenus medius and is formed from the upper four cervical nerves. It has both sensory and motor components, its cutaneous branches supplying the front and the side of the neck. Cervical plexus block is an important regional anaesthetic technique. Knowledge of the posterior triangle is essential in performing a cervical plexus block. The posterior triangle of the neck is formed by the posterior border of sternocleidomastoid anteriorly and trapezius posteriorly, its base being the middle third of the clavicle. The roof of the posterior triangle is the deep cervical fascia and the floor is the prevertebral fascia which overlies the scalene muscles (see Figure 1). The cervical plexus does not lie within the posterior triangle as it is deep to the prevertebral fascia and partially covered by the upper part of the sternocleidomastoid muscle. The cutaneous branches of the cervical plexus pierce the fascia at the posterior border of sternocleidomastoid and do lie within the posterior triangle. The cervical plexus is formed from the anterior rami of C1, C2, C3 and C4, proximal to the brachial plexus. There is a segmental muscular supply to the prevertebral muscles, and branches from C1, C2 and C3 to ansa cervicalis to supply the infrahyoid muscles and thyrohyoid. The motor supply to trapezius and sternocleidomastoid is via the accessory nerve. However, occasionally there are some contributory motor fibres from C3 and C4 to trapezius. The phrenic nerve supplying the diaphragm is predominantly formed from C4. However, there is a small contribution from C3 and C4 (hence the traditional rhyme ‘C3, 4, 5 keep the diaphragm alive’). Cutaneous branches of the cervical plexus (from superior to inferior) are as follows:
Great auricular nerve
Parotid gland
Lesser occipital nerve
Trapezius Sternocleidomastoid
Accessory nerve
Transverse cervical nerve Supraclavicular nerves C3 and C4 to trapezius Omohyoid Transverse cervical artery
Figure 1 Right posterior triangle.
Marco L Baroni FRCS (Gen Surg) is a Consultant Vascular Surgeon at York Hospital, York, UK. Conflicts of interest: none declared. David C Berridge DM FRCS (Eng) (Ed) is a Consultant Vascular Surgeon at Leeds General Infirmary, Leeds, UK. Conflicts of interest: none declared.
ANAESTHESIA AND INTENSIVE CARE MEDICINE 11:5
201
Ó 2010 Elsevier Ltd. All rights reserved.