Arm

For the processor architecture, see ARM (computing)

An arm is a particular upper limb appendage having varying usage and strength within the animal kingdom. In humans it is made up of three distinct bones:

• Humerus: (upper arm)
• Radius: (outer bone of the forearm, when supinated)
• Ulna: (inner bone of the forearm, when supinated)

The hands have these bones:

• Carpals: ("wrist bones,"
• Metacarpals: (longer bones in the "palm")
• Phalanges: (s. phalanx; two in the pollex, or thumb; three four the remaining four fingers)

The upper region of the arm has the following muscles:

• Deltoid ("shoulder", anterior, lateral, and posterior sections)
• Biceps brachii (the front, two heads)
• Triceps brachii (the back, three heads)

The forearm has these muscles:

• Brachioradialis (connects
• Supinator (turns forearm up)
• Pronator quadratus (turns forearm down)
• Flexor carpi radialis (flexes forearm)
• Flexor digitorum superficialis (flexes fingers)
• Flexor pollicis longus (flexes thumb)
• Extensor carpi radialis longus and brevis (straightens forearm)
• Extensor carpi ulnarus (straightens forearm)
• Extensor digitorum (straightens fingers)

Also, the hands have many muscles for fine control of the fingers.

Sources

http://encyclopedia2.thefreedictionary.com/arm