Lymph is present throughout the body, and circulates through lymphatic vessels. These drain into and from lymph nodesafferent vessels drain into nodes, and efferent vessels from nodes. When lymph fluid enters a node, it drains into the node just beneath the capsule in a space called the subcapsular sinus. The subcapsular sinus drains into trabecular sinuses and finally into medullary sinuses. The sinus space is criss-crossed by the pseudopods of macrophages, which act to trap foreign particles and filter the lymph. The medullary sinuses converge at the hilum and lymph then leaves the lymph node via the "efferent lymphatic vessel" towards either a more central lymph node or ultimately for drainage into a central venous subclavian blood vessel.