SUBCLAVIAN REGION, REGIO INFRACLAVICULARIS
The subclavian region belongs both to the thorax and to the upper limb. Since the layers of the subclavian region take part in forming the axillary fossa, and the main neurovascular fascicle of the upper limb, the axillary fascicle, adjoins them, the topographic anatomy studies the subclavian region as a part of the shoulder girdle.
The surface landmarks are the clavicle, the sternum, the pectoralis major muscle, and the anterior border of the deltoid. Beneath the clavicle, between the clavicular portion of the pectoralis major and the anterior border of the deltoid, at the borderline between the outer and middle thirds of the clavicle quite often we can see the infraclavicular [Mohrenheim] fossa, fossa infraclavicularis. Distally it goes on as the deltopectoral sulcus, sulcus deltopectoralis that extends along the anterior border of the deltoid up to the lateral sulcus of the arm. Deep in this sulcus, 1.5-2 cm beneath the clavicle, it is possible to palpate the coracoid process of the scapula, processus coracoideus.
Limits: the superior - the clavicle; the medial - the lateral border of the sternum; the inferior - a horizontal line corresponding to the third intercostal space; the lateral - the anterior border of the deltoid.
Projections (projective lines). By the surface landmarks, it is possible to draw projections of the following structures.
From the anterior ends of the III-V ribs up to the coracoid process, the pectoralis minor projects as a small triangle (fig. 2.1). With the help of this muscle, on the skin of the subclavian region we can construct the projective lines of three triangles: the clavipectoral, pectoral and subpectoral (trigonum clavipectorale, trigonum pectorale and trigonum subpectorale). Within the limits of these triangles, they usually study the topography of the axillary neurovascular fascicle: a., v. axillaris, plexus brachialis and its branches (in detail see the section «Axillary region»).