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Upper Extremity Regional Anesthesia: Overview & Anatomy

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Authors

Victor Huang, MD, CAQ-SM
Assistant Professor
Department of Emergency Medicine
New York Presbyterian Queens, Weill Cornell Medical College

Upper Extremity Neuranatomy

  • The shoulder and upper extremity are innervated by branches off the brachial plexus
  • The brachial plexus (BP) is a network of nerves formed by branches of the ventral (anterior) rami of cervical nerves C5, C6, C7, C8 and thoracic nerve T1
  • The cervical roots (C5-T1) converge to form three trunks: superior (C5-C6), middle (C7), inferior (C8-T1). These emerge between the anterior and middle scalenes.[1]Zisquit J, Nedeff N. Interscalene Block. In: StatPearls. StatPearls Publishing; 2020. Accessed January 26, 2021. http://www.ncbi.nlm.nih.gov/books/NBK519491
  • The trunks continue to the level of the clavicle, and then divide each into an anterior and posterior divisions -> Fibers from the divisions rearrange to form lateral, medial, and posterior cords -> peripheral nerves branch out from the three cords
  •  
  • Brachial Plexus
    • The brachial plexus arises from spinal cord nerve roots C5 – T1 and has five subdivisions: roots, trunks, divisions, cords, and branches [2] Forro SD, Lowe JB. Anatomy, Shoulder and Upper Limb, Arm Structure and Function. StatPearls Publishing; 2018. Accessed August 9, 2020. http://www.ncbi.nlm.nih.gov/pubmed/29939618 [3] Schuenke M, Schulte E, Schumacher U. Neurovasculature. In: Gilroy AM, MacPherson BR, eds. Atlas of Anatomy. 3rd ed. Thieme; 2016:360-392. . The upper extremity is innervated by the brachial plexus and its primary branches, the musculocutaneous, axillary, median, ulnar, and radial nerves [4]Kelly JJ, Younga J. Regional Anesthesia of the Thorax and Extremities. In: Roberts JR, Custalow CB, Thomsen TW, eds. Roberts and Hedges’ Clinical Procedures in Emergency Medicine and Acute Care. … Continue reading [5] Forro SD, Lowe JB. Anatomy, Shoulder and Upper Limb, Arm Structure and Function. StatPearls Publishing; 2018. Accessed August 9, 2020. http://www.ncbi.nlm.nih.gov/pubmed/29939618 [6] Capek A, Frca M, Dolan J, Ffarcsi Edra P. Ultrasound-guided peripheral nerve blocks of the upper limb. Contin Educ Anaesth Crit Care Pain. 2014;15(3):160-165. doi:10.1093/bjaceaccp/mku048

Image 1. Brachial Plexus Anatomy

  • Musculocutaneous Nerve
    • The musculocutaneous nerve is supplied by nerve roots C5 – C7. It pierces the coracobrachialis muscle then travels between the biceps brachii and the brachialis muscle. It innervates these three muscles and allows for flexion and supination at the elbow. The nerve continues into the forearm lateral to the biceps tendon in the cubital fossa to become the lateral cutaneous nerve that provides sensation to the lateral forearm [7] Forro SD, Lowe JB. Anatomy, Shoulder and Upper Limb, Arm Structure and Function. StatPearls Publishing; 2018. Accessed August 9, 2020. http://www.ncbi.nlm.nih.gov/pubmed/29939618 [8] Schuenke M, Schulte E, Schumacher U. Neurovasculature. In: Gilroy AM, MacPherson BR, eds. Atlas of Anatomy. 3rd ed. Thieme; 2016:360-392. [9] Capek A, Frca M, Dolan J, Ffarcsi Edra P. Ultrasound-guided peripheral nerve blocks of the upper limb. Contin Educ Anaesth Crit Care Pain. 2014;15(3):160-165. doi:10.1093/bjaceaccp/mku048  

Image 2. Musculocutaneous nerve anatomy

  • Median Nerve
    • The median nerve is supplied by nerve roots C6 – T1. It travels from the axilla to the elbow, starting lateral to the brachial artery, but crosses over to become medial to the artery near the antecubital fossa. In the forearm, it travels between the flexor digitorum superficialis and flexor digitorum profundus muscles. The two branches are the anterior interosseous nerve (AIN), which supplies motor function to the flexor muscles of the anterior forearm, and the palmar cutaneous nerve, which provides sensation over the thenar eminence. The median nerve continues into the carpal tunnel and splits into the recurrent branch, which supplies motor function to the thenar muscles, and the palmar digital branch, which provides sensation to the palmar surface of radial 3 ½ digits and motor to the two lumbricals on the radial aspect [10] Forro SD, Lowe JB. Anatomy, Shoulder and Upper Limb, Arm Structure and Function. StatPearls Publishing; 2018. Accessed August 9, 2020. http://www.ncbi.nlm.nih.gov/pubmed/29939618 [11] Schuenke M, Schulte E, Schumacher U. Neurovasculature. In: Gilroy AM, MacPherson BR, eds. Atlas of Anatomy. 3rd ed. Thieme; 2016:360-392. [12] Capek A, Frca M, Dolan J, Ffarcsi Edra P. Ultrasound-guided peripheral nerve blocks of the upper limb. Contin Educ Anaesth Crit Care Pain. 2014;15(3):160-165. doi:10.1093/bjaceaccp/mku048 [13]Canders CP, Morales DA, Sha SW. Ultrasound-guided Nerve Blocks in the Emergency Department. Relias Media. Published March 2018. Accessed August 2, 2020. … Continue reading

Image 3. Median nerve anatomy

  • Ulnar Nerve
    • The ulnar nerve is supplied by nerve roots C8 – T1. It travels along the medial head of the triceps and enters the cubital tunnel at the elbow. It travels along the medial aspect of the forearm, just medial to the ulnar artery. The muscular branch of the ulnar nerve innervates the flexor carpi ulnaris, and the ulnar portion of the flexor digitorum profundus. The palmar and dorsal cutaneous nerves branch off just proximal to the wrist. Distal to the wrist, the nerve divides into the superficial and the deep terminal branch. The nerve provides sensation to the medial aspect of the dorsal and volar hand, as well as the medial 1 ½ digits. It supplies motor function to the rest of the intrinsic muscles of the hand including the hypothenar, interossei, and medial two lumbrical muscles [14] Forro SD, Lowe JB. Anatomy, Shoulder and Upper Limb, Arm Structure and Function. StatPearls Publishing; 2018. Accessed August 9, 2020. http://www.ncbi.nlm.nih.gov/pubmed/29939618  [15] Capek A, Frca M, Dolan J, Ffarcsi Edra P. Ultrasound-guided peripheral nerve blocks of the upper limb. Contin Educ Anaesth Crit Care Pain. 2014;15(3):160-165. doi:10.1093/bjaceaccp/mku048 [16]Canders CP, Morales DA, Sha SW. Ultrasound-guided Nerve Blocks in the Emergency Department. Relias Media. Published March 2018. Accessed August 2, 2020. … Continue reading [17]Wroe P, Nagdev A. How to Perform Ultrasound-Guided Forearm Nerve Blocks to Provide Non-Drug Pain Relief for Acute Injuries. ACEP Now. Published October 2016. Accessed August 4, 2020. … Continue reading

Image 4. Ulnar nerve anatomy

  • Radial Nerve
    • The radial nerve is supplied by every nerve root of the brachial plexus, C5 – T1. It travels in the radial groove along the posterior surface of the humerus and courses over the lateral epicondyle, between the brachialis and brachioradialis. It divides into the deep and superficial branches. The deep branch supplies the motor innervation to the extensor muscles of the wrist and digits, and it becomes the posterior interosseous nerve after crossing the supinator. The superficial radial nerve travels medial to the radial artery and vein, and it provides sensation to the lateral aspect of the dorsal hand and the dorsal surface of the lateral 3 ½ digits [18] Forro SD, Lowe JB. Anatomy, Shoulder and Upper Limb, Arm Structure and Function. StatPearls Publishing; 2018. Accessed August 9, 2020. http://www.ncbi.nlm.nih.gov/pubmed/29939618 [19] Capek A, Frca M, Dolan J, Ffarcsi Edra P. Ultrasound-guided peripheral nerve blocks of the upper limb. Contin Educ Anaesth Crit Care Pain. 2014;15(3):160-165. doi:10.1093/bjaceaccp/mku048 [20]Canders CP, Morales DA, Sha SW. Ultrasound-guided Nerve Blocks in the Emergency Department. Relias Media. Published March 2018. Accessed August 2, 2020. … Continue reading [21]Wroe P, Nagdev A. How to Perform Ultrasound-Guided Forearm Nerve Blocks to Provide Non-Drug Pain Relief for Acute Injuries. ACEP Now. Published October 2016. Accessed August 4, 2020. … Continue reading [22]Lin J-A, Bendtsen TF, Lopez AM, Jalil H. Ultrasound-Guided Blocks at the Elbow. NYSORA. Published 2020. Accessed August 3, 2020. … Continue reading

Image 5. Radial nerve anatomy

Nerve Ultrasound Principles

  • Ultrasound is a helpful adjunct when performing peripheral nerve blocks, allowing visualization of the nerve and surrounding important structures. 
  • Nerves have a slightly elliptical shape and a “honeycomb” appearance in short-axis view on ultrasound [23] Capek A, Frca M, Dolan J, Ffarcsi Edra P. Ultrasound-guided peripheral nerve blocks of the upper limb. Contin Educ Anaesth Crit Care Pain. 2014;15(3):160-165. doi:10.1093/bjaceaccp/mku048 [24]Canders CP, Morales DA, Sha SW. Ultrasound-guided Nerve Blocks in the Emergency Department. Relias Media. Published March 2018. Accessed August 2, 2020. … Continue reading [25] Brown JM, Yablon CM, Morag Y, Brandon CJ, Jacobson JA. US of the peripheral nerves of the upper extremity: A landmark approach. Radiographics. 2016;36(2):452-463. doi:10.1148/rg.2016150088 The hypoechoic nerve fascicles are surrounded by hyperechoic epineurium. Nerves are less anisotropic and less tightly bound when compared to tendons [26] Brown JM, Yablon CM, Morag Y, Brandon CJ, Jacobson JA. US of the peripheral nerves of the upper extremity: A landmark approach. Radiographics. 2016;36(2):452-463. doi:10.1148/rg.2016150088 [27] Jacobson JA. Interventional Techniques. In: Fundamentals of Musculoskeletal Ultrasound. 3rd ed. Philadelphia,PA: Elsevier; 2018:407-442.
  • Vasculature: Arteries and veins area as circular structures in short-axis view on ultrasound, and can be identified by color flow Doppler. Arteries are pulsatile and non-compressible while veins are non-pulsatile and easily compressible [28] Capek A, Frca M, Dolan J, Ffarcsi Edra P. Ultrasound-guided peripheral nerve blocks of the upper limb. Contin Educ Anaesth Crit Care Pain. 2014;15(3):160-165. doi:10.1093/bjaceaccp/mku048

Image 6. Cross-sectional image of the median nerve. Note “honeycomb” appearance. Hypoechoic nerve fascicles are surrounded by hyperechoic epineurium. 

Overview of Blocks By Site

  • General
    • The following nerve block techniques follow the general procedure as described in the previous chapter. Unless otherwise stated, the techniques below utilize ultrasound-guidance to visualize the nerve in short-axis, with an in-plane needle approach. See dedicated chapters for more detail.
  • Shoulder
    • Interscalene: The interscalene brachial plexus block anesthetizes the shoulder and upper arm (and less effectively the elbow and forearm) and is utilized during surgical procedures, shoulder dislocation reduction, and complex laceration repairs. The block affects the upper and middle trunks of the brachial plexus, but inconsistently affects the lower trunk which provides sensory innervation in the ulnar nerve distribution. The ultrasound probe is placed over the lateral aspect of the neck, transverse to the scalene muscles. The brachial plexus is located in between the anterior and middle scalene muscles. The needle is inserted in-plane from a posterior-to-anterior approach. This block should be avoided in patients with underlying pulmonary conditions because serious complications include pneumothorax and phrenic nerve involvement that results in paralysis of the diaphragm [29]Kelly JJ, Younga J. Regional Anesthesia of the Thorax and Extremities. In: Roberts JR, Custalow CB, Thomsen TW, eds. Roberts and Hedges’ Clinical Procedures in Emergency Medicine and Acute Care. … Continue reading [30] Hadzic A. Ultrasound-Guided Nerve Blocks. Hadzic’s Peripheral Nerve Blocks and Anatomy for Ultrasound-Guided Regional Anesthesia. 2nd ed. McGraw Hill; 2012:345-395 [31] Bhoi S, Chandra A, Galwankar S. Ultrasound-guided nerve blocks in the emergency department. J Emergencies, Trauma Shock. 2010;3(1):82-88. doi:10.4103/0974-2700.58655

Image 7. Interscalene Overview

See Chapter 14 - Regional Anesthesia - Shoulder
  • Elbow/Forearm/Wrist
    • Supraclavicular: The supraclavicular block provides anesthesia to the upper limb (with the exception of the medial aspect of the proximal arm and shoulder). It targets the distal trunks/proximal divisions of the brachial plexus above the clavicle. This block is useful for pathology to the elbow, forearm, and wrist. The patient can be positioned supine or semi-sitting with the head of bed up. The head should be turned towards the contralateral side. Start scanning just above the clavicle at its midpoint, with the ultrasound probe parallel to the clavicle. Identify the subclavian artery (SA). The brachial plexus is seen laterally and superficial to the artery, as a collection of hypoechoic oval structures (the classic description of a “bundle of grapes”. The needle will travel from lateral to medial, and avoid puncturing the nerve bundles.

Image 8. Supraclavicular block anatomy

See Chapter 15 - Regional Anesthesia - Elbow/Forearm/Wrist
    • Infraclavicular: The infraclavicular block provides anesthesia to the same region as the supraclavicular block, but with a different approach. It also provides anesthesia to the upper limb (with the exception of the medial aspect of the proximal arm and shoulder). Injecting below the clavicle, it targets the lateral/posterior/medial cords of the brachial plexus. This block is equally useful for pathology to the elbow, forearm, and wrist. There have been several approaches described for this block, including the coracoid approach and the retroclavicular approach. The most commonly used is the coracoid approach. With the patient supine and head turned towards the contralateral side, palpate the coracoid process of the scapula. Place the ultrasound probe medial to the coracoid process inferior to the clavicle. The transducer is positioned in a somewhat oblique position, with the inferior end of the probe angled towards the opposite hip. Identify the pectoralis major, pectoralis minor, and axillary artery. The three cords of the BP surround the axillary artery. Insert the needle from lateral to medial, in-plane with the ultrasound.

Image 9. Infraclavicular block ultrasound anatomy

See Chapter 15 - Regional Anesthesia - Elbow/Forearm/Wrist
  • Hand
    • Nerve blocks of the median, ulnar and radial nerves at the level of the forearm provide anesthesia to their respective distribution in the hand, but not to the forearm or wrist [32]Canders CP, Morales DA, Sha SW. Ultrasound-guided Nerve Blocks in the Emergency Department. Relias Media. Published March 2018. Accessed August 2, 2020. … Continue reading [33]Wroe P, Nagdev A. How to Perform Ultrasound-Guided Forearm Nerve Blocks to Provide Non-Drug Pain Relief for Acute Injuries. ACEP Now. Published October 2016. Accessed August 4, 2020. … Continue reading 
    • Median Nerve: The patient’s arm should be supinated and slightly abducted. The transducer is placed in the transverse axis at the volar aspect of the mid-forearm. The nerve lies between the flexor digitorum profundus and superficialis muscle. Since there are no associated vessels, the needle can be inserted from either the medial or lateral aspect [34] Capek A, Frca M, Dolan J, Ffarcsi Edra P. Ultrasound-guided peripheral nerve blocks of the upper limb. Contin Educ Anaesth Crit Care Pain. 2014;15(3):160-165. doi:10.1093/bjaceaccp/mku048 [35]Canders CP, Morales DA, Sha SW. Ultrasound-guided Nerve Blocks in the Emergency Department. Relias Media. Published March 2018. Accessed August 2, 2020. … Continue reading [36]Wroe P, Nagdev A. How to Perform Ultrasound-Guided Forearm Nerve Blocks to Provide Non-Drug Pain Relief for Acute Injuries. ACEP Now. Published October 2016. Accessed August 4, 2020. … Continue reading

Image 10. Median nerve block ultrasound

    • Radial Nerve: The patient’s forearm should be rested in between a supinated and neutral position. The transducer is placed in the transverse axis over the radial aspect of the mid-forearm. The superficial radial nerve lies lateral to the radial artery and can be tracked proximally until it separates from the artery. The needle should be inserted at the radial aspect of the forearm to avoid intravascular injection [37] Capek A, Frca M, Dolan J, Ffarcsi Edra P. Ultrasound-guided peripheral nerve blocks of the upper limb. Contin Educ Anaesth Crit Care Pain. 2014;15(3):160-165. doi:10.1093/bjaceaccp/mku048 [38]Canders CP, Morales DA, Sha SW. Ultrasound-guided Nerve Blocks in the Emergency Department. Relias Media. Published March 2018. Accessed August 2, 2020. … Continue reading [39]Wroe P, Nagdev A. How to Perform Ultrasound-Guided Forearm Nerve Blocks to Provide Non-Drug Pain Relief for Acute Injuries. ACEP Now. Published October 2016. Accessed August 4, 2020. … Continue reading

Image 11. Radial nerve block ultrasound

    • Ulnar Nerve: The patient’s shoulder should be abducted and slightly externally rotated and the elbow flexed to 90 degrees. The transducer is placed in the transverse axis at the medial aspect of the mid-forearm. The nerve should be tracked proximally until it separates from the ulnar artery. The needle should be inserted at the medial aspect of the forearm [40] Capek A, Frca M, Dolan J, Ffarcsi Edra P. Ultrasound-guided peripheral nerve blocks of the upper limb. Contin Educ Anaesth Crit Care Pain. 2014;15(3):160-165. doi:10.1093/bjaceaccp/mku048 [41]Canders CP, Morales DA, Sha SW. Ultrasound-guided Nerve Blocks in the Emergency Department. Relias Media. Published March 2018. Accessed August 2, … Continue reading [42]Wroe P, Nagdev A. How to Perform Ultrasound-Guided Forearm Nerve Blocks to Provide Non-Drug Pain Relief for Acute Injuries. ACEP Now. Published October 2016. Accessed August 4, … Continue reading

Image 12. Ulnar nerve block ultrasound

See Chapter 16 - Hand
  • Other Techniques
    • Digital Nerve Blocks: The finger is innervated by four digital nerves, two palmar and two dorsal, that are derived from the median, ulnar and radial nerves. Digital blocks are a very useful modality of anesthesia for finger injuries that is preferred over local infiltration due to lower volume of the injectate resulting in less pain and swelling [43]Kelly JJ, Younga J. Regional Anesthesia of the Thorax and Extremities. In: Roberts JR, Custalow CB, Thomsen TW, eds. Roberts and Hedges’ Clinical Procedures in Emergency Medicine and Acute Care. … Continue reading.
    • Transthecal Block: The transthecal digital block is a single injection into the flexor tendon sheath just proximal to the MCP joint. The local anesthetic will distribute along the length of the tendon sheath, diffuse out and anesthetize all four digital nerves [44]Kelly JJ, Younga J. Regional Anesthesia of the Thorax and Extremities. In: Roberts JR, Custalow CB, Thomsen TW, eds. Roberts and Hedges’ Clinical Procedures in Emergency Medicine and Acute Care. … Continue reading.
    • Hematoma Block: A hematoma block can be performed at the site of a fracture by first sterilizing the skin. The needle should be inserted into the hematoma at the fracture site, making sure to avoid any contaminated or infected areas. Aspirate blood and then inject 5 – 15 mL of lidocaine depending on the size of the fracture. Anesthesia should occur in 5 – 10 minutes [45]Kelly JJ, Younga J. Regional Anesthesia of the Thorax and Extremities. In: Roberts JR, Custalow CB, Thomsen TW, eds. Roberts and Hedges’ Clinical Procedures in Emergency Medicine and Acute Care. … Continue reading.

Image 12. Transthecal block

Pearls and Pitfalls

  • Due to overlap of sensory innervation of adjacent dermatomes, two or more peripheral nerves may need to be anesthetized to provide adequate anesthesia [46]Kelly JJ, Younga J. Regional Anesthesia of the Thorax and Extremities. In: Roberts JR, Custalow CB, Thomsen TW, eds. Roberts and Hedges’ Clinical Procedures in Emergency Medicine and Acute Care. … Continue reading [47] Capek A, Frca M, Dolan J, Ffarcsi Edra P. Ultrasound-guided peripheral nerve blocks of the upper limb. Contin Educ Anaesth Crit Care Pain. 2014;15(3):160-165. doi:10.1093/bjaceaccp/mku048 [48]Wroe P, Nagdev A. How to Perform Ultrasound-Guided Forearm Nerve Blocks to Provide Non-Drug Pain Relief for Acute Injuries. ACEP Now. Published October 2016. Accessed August 4, 2020. … Continue reading
  • Complications: Risks of peripheral nerve blocks include vascular injury, intravascular injection, nerve injury, intraneural injection, infection, hematoma and local anesthetic systemic toxicity (LAST). 
  • DO NOT INJECT DIRECTLY INTO THE NERVE!

References[+]