Muscles in the Medial Upper Arm, Axillary Region, and Lateral Chest Wall
The key muscles in these anatomical areas relevant to brachioplasty include the brachialis and biceps brachii in the medial upper arm, the pectoralis major and minor in the lateral chest wall, and several accessory muscles in the axillary region including Langer's axillary arch (present in approximately 10% of individuals) and the latissimus dorsi.
Primary Muscles by Region
Medial Upper Arm
- Brachialis muscle: This has two distinct heads—a larger superficial head originating from the anterolateral humerus with longitudinal fibers inserting on the ulnar tuberosity, and a smaller deep head with fan-shaped fibers inserting on the coronoid process 1
- Biceps brachii: The standard muscle of the anterior arm, though accessory heads originating from the humeral shaft occur and can compress neurovascular structures 2
Axillary Region
The axilla represents the anatomical space between the lateral chest wall and medial upper limb. Key structures include:
- Pectoralis major and minor: These form the anterior axillary wall, with the pectoralis minor defining one of the compression spaces in thoracic outlet syndrome 3
- Latissimus dorsi: Forms the posterior axillary boundary and can be utilized in reconstructive procedures 4
Lateral Chest Wall
- Pectoralis major: The primary muscle of the anterior chest
- Pectoralis minor: Lies deep to the pectoralis major
- Serratus anterior: Along the lateral thoracic wall
Clinically Significant Accessory Muscles
Surgeons must be aware that accessory muscles occur with surprisingly high frequency in these regions. The most common variants include:
- Langer's axillary arch: Present in 10.30% of cadaveric studies, this muscular slip extends from the latissimus dorsi across the axilla to insert on the pectoralis major 5, 6
- Sternalis muscle: Found in 7.67% of individuals, can extend to both anterior and posterior sternal surfaces 5
- Chondrocoracoideus (Wood's muscle): Extends from costal cartilages toward the coracoid process 5
- Pectoralis quartus, pectoralis minimus, and pectoralis intermedius: Additional pectoral muscle variants 5
Surgical Implications for Brachioplasty
When performing brachioplasty involving these regions, the surgeon encounters:
Neurovascular structures: The brachial plexus passes between the anterior and middle scalene muscles with the subclavian artery, forming trunks that travel with vessels through the infraclavicular region and axilla 7
Nerve supply variations: The radial nerve supplies the inferolateral fibers of the deep brachialis head, forming a dynamic stabilizing sling around the elbow 1. The pectoral nerves can have atypical origins directly from trunk divisions rather than the lateral cord 8
Perforator-based flaps: The lateral thoracic region contains perforators that can be utilized for autoaugmentation procedures when addressing upper body contouring 4
Critical Pitfalls
- Accessory muscle misidentification: With a combined incidence exceeding 10% for axillary arch and sternalis muscles alone, these structures are common enough to encounter regularly in practice 5
- Neurovascular compression: Accessory muscle heads can cause nerve entrapment neuropathy and mysterious pain syndromes 2
- Surgical planning: Failure to identify variant anatomy preoperatively increases risk of iatrogenic nerve injury 8
The anatomical complexity of this region, combined with the high frequency of muscular variants, necessitates thorough preoperative imaging and careful intraoperative identification of structures during any upper body contouring procedure.