Trachea front and sides of the trachea to protect and maintain the airway. In front of the rings lies connective tissue and skin. Several other structures pass or sit over it; the jugular arch, which joins the two anterior jugular veins, sits in front of the upper part of the trachea. The sternohyoid and sternothyroid muscles stretch along its length, and the thyroid gland sits below this; with the isthmus of the gland overlying the second to fourth rings. The first tracheal ring is broader than the rest, and often divided at one end; it is connected by the cricotracheal ligament
Human-body model primarily for manufacturing environments to quantify a integrated circuit to survive the manufacturing process. A similar standard, IEC 61000-4-2, is used for system level testing and quantifies protection levels for a real world ESD event in an uncontrolled environment. In both JS-001-2012 and MIL-STD-883H the charged human body is modeled by a 100 pF capacitor and a 1500 ohm discharging resistance. During testing, the capacitor is fully charged to several kilovolts (2 kV, 4 kV, 6 kV and 8 kV are typical standard levels) and then discharged through the resistor connected in series to the device under test. Human-body model