The trachea bifurcates, or divides, into two branches at its most distal portion and forms the bronchi. The bifurcation is reinforced by a cartilaginous plate called the carina. Like the trachea, each bronchus is made up of cartilaginous rings to keep the lumen open as it goes into the lung. As the branches get smaller, they are called secondary bronchi and segmental (or tertiary) bronchi.
Pins and Needles - Paraesthesia. The most common cause of pins and needles is a moderately pinched nerve. Pins and needles is referred to as paraesthesia in the medical community. Did you know that feeling pins and needles can actually be a worse sign than having pain in your arm or leg.
Tingling hands, feet, or both is an extremely common and bothersome symptom. Such tingling can sometimes be benign and temporary. For example, it could result from pressure on nerves when your arm is crooked under your head as you fall asleep. Or it could be from pressure on nerves when you cross your legs too long. In either case, the pins and needles effect -- which is usually painless -- is soon relieved by removing the pressure that caused it. In many cases, however, tingling in the hands, feet, or both can be severe, episodic, or chronic.