What are the major neurovascular structures to be careful of in the arm during surgical procedures?

Major Neurovascular Structures in the Arm to Consider During Surgical Procedures

The most important neurovascular structures to be careful of during surgical procedures in the arm are the median nerve, ulnar nerve, radial nerve, musculocutaneous nerve, brachial artery and vein, basilic vein, and deep brachial artery. 1

Anatomical Arrangement and Location

Medial Neurovascular Bundle

• The majority of critical neurovascular structures in the arm form a medial neurovascular bundle that can be accessed through a 2×2 inch "key window" on the medial surface of the arm, approximately 2 inches distal to the axillary fold 1
• The neurovascular structures form a consistent triangular pattern around the axillary artery that is readily identifiable with ultrasound 2

Nerve Locations Relative to the Axillary Artery

• Median nerve: Most commonly located in the anterior and anterolateral positions (12 and 9 o'clock arc) relative to the axillary artery in 88% of patients 2
• Ulnar nerve: Primarily found in the anteromedial position (12-3 o'clock arc) relative to the axillary artery in 85% of patients, with a secondary location anterolaterally (9-10 o'clock) in 11% 2
• Radial nerve: Predominantly located in the posterior and posteromedial positions (4-6 o'clock arc) relative to the axillary artery in 83% of patients 2

Critical Distances During Surgical Approaches

Subpectoral Region

• The musculocutaneous nerve is particularly vulnerable, located only 10.1 mm (range: 6-18 mm) from common surgical sites in the subpectoral region 3
• The radial nerve and deep brachial artery are at high risk, positioned only 7.4 mm (range: 2-12 mm) and 5.7 mm (range: 1-10 mm) deep to medially placed retractors, respectively 3
• Arm position significantly affects nerve location: external rotation moves the musculocutaneous nerve 11.3 mm further away from surgical sites compared to internal rotation 3

Coracoid Region

• The lateral cord of the brachial plexus is at greatest risk during procedures around the coracoid tip, located approximately 28.5 mm from the anteromedial portion 4
• The axillary nerve is at highest risk during dissection near the base of the coracoid, positioned about 29.3 mm from the anteromedial aspect 4
• The axillary artery is relatively safer, positioned 36.8 mm from the coracoid tip and 42.7 mm from the coracoid base 4

Safer Zones for Surgical Approaches

Posterior Triceps Region

• The area overlying the triceps 8-10 cm proximal to the medial epicondyle and 3-5 cm posterior to the bicipital sulcus contains fewer major neurovascular structures 5
• This posterior approach may minimize risk of neurovascular injury during procedures compared to approaches over the biceps 5

Arm Positioning Considerations

• Flexing the elbow with the hand positioned under the head displaces the ulnar nerve anteriorly toward the bicipital sulcus, potentially creating a safer posterior working zone 5
• External rotation of the arm (45°) significantly increases the distance between the musculocutaneous nerve and surgical sites compared to internal rotation 3

Surgical Precautions

During Thoracic Outlet Procedures

• Careful attention must be paid to the brachial plexus, subclavian artery, and subclavian vein at the superior thoracic outlet, as compression of these structures can lead to neurological, arterial, or venous thoracic outlet syndrome 6
• The costoclavicular triangle (formed by the clavicle, anterior scalene muscle, and first rib) and the interscalene triangle (formed by anterior scalene, middle scalene, and first rib) contain critical neurovascular structures 6

During Vascular Access Procedures

• When performing arterial access procedures, careful technique and proper hemostasis are essential to prevent complications like hematoma formation that could compress adjacent nerves 7
• Median nerve injury is a potential complication of brachial artery access, requiring vigilant post-procedure monitoring for signs of neurovascular compromise 7

By understanding the precise anatomical relationships of these neurovascular structures and implementing appropriate surgical techniques, surgeons can minimize the risk of iatrogenic injury during procedures involving the arm.