Lesser supraclavicular fossa

The lesser supraclavicular fossa is defined anatomically as the small triangular depression located above the clavicle, bounded medially by the lateral border of the sternocleidomastoid muscle and laterally by the medial border of the trapezius muscle. Its floor is formed by the clavicle, and it is roofed by skin and superficial fascia. This fossa is clinically significant as it overlies important neurovascular structures, including the subclavian vessels and the brachial plexus, and is a common site for palpable lymphadenopathy and other masses.