[Sonographic anatomy of the axilla]

The axilla represents a region of special interest for small-part sonography. It is easy to demonstrate musculocutaneous, osseous, neurovascular and lymphatic structures. Especially in the presence of breast malignomas with lymphatic drainage to the axillary region sonography of the axillary lymphatic tracts and nodes is essential. The examination is performed with a linear 7.5 MHz transducer with the patient in supine position and the arm hyperabducted. The transducer is directed in transversal and sagittal planes and along the axillary vessels. It is of importance to know exactly the complex topographic anatomy of the axilla. The very dominant pectoral muscles serve as guiding structures. In their vicinity one can find some important groups of lymph nodes. The last station of axillary lymph nodes is the apical group situated along the axillary neurovascular bundle. With their typical echo, the head of the humerus and the coracoid-process facilitate the orientation. Ultrasound is now generally available and should always be used as a secondary method of examination, it breast malignomas are present or suspected in mammogramms, since it supplies important clinical information.