Sinoatrial node is influenced by nerves that supply it. The sinoatrial node is a banana-shaped structure that varies in size, usually between 10-30 millimeters (mm) long, 5–7 mm wide, and 1–2 mm deep. The SA node is located in the wall (myocardium) of the right atrium, laterally to the entrance of the superior vena cava in a region called the sinus venarum (hence "sino-" + "atrial)". It is positioned roughly between a groove called the crista terminalis located on the internal surface of the heart and the corresponding sulcus terminalis, on the external surface. These grooves run between the entrance of the
Lymph node biopsy enlargement (swollen glands or lymphadenitis). It may also determine whether tumors in the lymph node are cancerous or noncancerous. Enlarged lymph nodes may be caused by a number of conditions, ranging from very mild infections to serious malignancies. Benign conditions can often be distinguished from cancerous and infectious processes by microscopic examination. The pathologist may also perform additional tests on the lymph node tissue to assist in making a diagnosis. Some of the conditions where abnormal values are obtained are: Lymph node biopsies may be performed to evaluate the spread of cancer. See Lymphadenectomy#With_sentinel_node_biopsy. However, Sentinel lymph node biopsy for