Difference between Nerve and Vein

Key Difference: Veins are large return vessels of the body which carry blood to the heart. They can be considered as blood return counterparts of arteries. Nerves are bundles of axons constituting the peripheral nervous system. They transmit information between periphery and central nervous system.

Veins are important blood vessels of the circulatory system. They transport blood to the heart. This blood is generally deoxygenated except form the pulmonary vein which goes form the lungs to the heart.

The structure of veins is quiet similar to arteries. It comprises of three layers. The outer most layer is known as Tunica Adventitia. It is very strong covering and comprises of connective tissues, collagen and elastic fibers. Next to it is the Tunica Media which is also known ass the middle layer. It comprises of smooth muscle and elastic fibres. Last is the Tunica Intima which is the innermost layer and comprises of smooth endothelial cells. The hollow section which carries blood is known as the lumen. They also contain valves which makes sure to avoid the back flow of blood. Veins contain blood under low pressure. Veins are originally red in color due to the blood content, however skin acts as a filter for the color and it is perceived as green.

Nerves are bundles of axons constituting the peripheral nervous system. Axons are fragile and thin cellular extensions through which neurons the specialized cells are able to send and receive signal to other cells. An axon is first wrapped in a connective tissue covering known as endoneurium.

These individual axons group to from fascicles which are wrapped in a covering consisting of connective tissue called the perineurium. Many of the fascicles are covered together by another layer of connective tissue known as epineurium in order to form a whole nerve. Nerves behave as highways by carrying signals between the brain and spinal cord and to the rest of the body. Nerves generally are found running along borders of other structures especially between different muscle groups. Most of the nerves are very small and almost invisible but most that can be seen are a pale yellow, almost white.

Thus, nerves and veins are completely different from each other. They are diffeent in context to structure, function, etc.

Comparison between Nerve and Vein:

	Nerve	Vein
Definition	Nerves are bundles of axons constituting the peripheral nervous system. Nerves behave as highways by carrying signals between the brain and spinal cord and to the rest of the body.	Blood vessels which transport deoxygenated blood to the heart except the pulmonary vein which goes from the lungs to the heart and carry oxygenated blood.
Types	Afferent, efferent and mixed nerves – some nerves work as one way highways. Some nerves carry signals only from the central nervous system. Some nerves work in 2 way street styles Cranial Nerves – are 12 pairs of nerves which emerge directly from brain and the brainstem Spinal nerves – refers to any of the paired peripheral nerves which arises from the spinal cord	Pulmonary veins – transport oxygen rich blood from lungs to the left portion of heart so that it can be pumped to the body Superior and Inferior carvae veins – they carry oxygen poor blood from the body to the heart
Associated with the	Nervous System	Blood Circulatory System
Contents of the femoral triangle	Femoral nerve – Innervates the anterior compartment of the thigh, and provides sensory branches for the leg and foot.	Femoral vein – The great saphenous vein drains into the femoral vein within the triangle.
Some related disorders	Carpal Tunnel Syndrome – median nerve is trapped at the wrist Diabetic Neuropathy – nerve endings are progressively damaged Neuralgia – referring to nerve pain	Venous Insufficiency – caused by damaged veins Post Phlebitis Venous Insufficiency – caused by the attack of blood clots
Color	Most of the nerves are very small and almost invisible but most that can be seen are a pale yellow, almost white.	Veins are originally red in color due to the blood content, however skin acts as a filter for the color and it is perceived as green.