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.