Main Difference
The main difference between Arm and Forearm is that the forearm and upper arm together and Forearm is a part of the body.
Arm
In human anatomy, the arm is the part of the upper limb between the glenohumeral joint (shoulder joint) and the elbow joint. In common usage, the arm extends to the hand. It can be divided into the upper arm, which extends from the shoulder to the elbow, the forearm which extends from the elbow to the hand, and the hand. Anatomically the shoulder girdle with bones and corresponding muscles is by definition a part of the arm. The Latin term brachium may refer to either the arm as a whole or to the upper arm on its own.
Forearm
The forearm is the region of the upper limb between the elbow and the wrist. The term forearm is used in anatomy to distinguish it from the arm, a word which is most often used to describe the entire appendage of the upper limb, but which in anatomy, technically, means only the region of the upper arm, whereas the lower “arm” is called the forearm. It is homologous to the region of the leg that lies between the knee and the ankle joints, the crus.
The forearm contains two long bones, the radius and the ulna, forming the radioulnar joint. The interosseous membrane connects these bones. Ultimately, the forearm is covered by skin, the anterior surface usually being less hairy than the posterior surface.
The forearm contains many muscles, including the flexors and extensors of the digits, a flexor of the elbow (brachioradialis), and pronators and supinators that turn the hand to face down or upwards, respectively. In cross-section the forearm can be divided into two fascial compartments. The posterior compartment contains the extensors of the hands, which are supplied by the radial nerve. The anterior compartment contains the flexors, and is mainly supplied by the median nerve. The flexor muscles are more massive than the extensors, because they work against gravity and act as anti-gravity muscles. The ulnar nerve also runs the length of the forearm.
The radial and ulnar arteries and their branches supply the blood to the forearm. These usually run on the anterior face of the radius and ulna down the whole forearm. The main superficial veins of the forearm are the cephalic, median antebrachial and the basilic vein. These veins can be used for cannularisation or venipuncture, although the cubital fossa is a preferred site for getting blood.
Arm (noun)
The portion of the upper human appendage, from the shoulder to the wrist and sometimes including the hand.
“She stood with her right arm extended and her palm forward to indicate “Stop!””
Arm (noun)
The extended portion of the upper limb, from the shoulder to the elbow.
“The arm and forearm are parts of the upper limb in the human body.”
Arm (noun)
A limb, or locomotive or prehensile organ, of an invertebrate animal.
“the arms of an octopus”
Arm (noun)
A long, narrow, more or less rigid part of an object extending from the main part or centre of the object, such as the arm of an armchair, a crane, a pair of spectacles or a pair of compasses.
“The robot arm reached out and placed the part on the assembly line.”
Arm (noun)
A bay or inlet off a main body of water.
“Shelburne Bay is an arm of Lake Champlain.”
Arm (noun)
A branch of an organization.
“the cavalry arm of the military service”
Arm (noun)
Power; might; strength; support.
“the arm of the law”
“the secular arm”
Arm (noun)
A pitcher
“The team needs to sign another arm in the offseason.”
Arm (noun)
One of the two parts of a chromosome.
Arm (noun)
A group of patients in a medical trial.
Arm (noun)
A weapon.
Arm (noun)
heraldic bearings or insignia
“The Duke’s arms were a sable gryphon rampant on an argent field.”
Arm (verb)
To take by the arm; to take up in one’s arms.
Arm (verb)
To supply with arms or limbs.
Arm (verb)
To supply with armour or (later especially) weapons.
Arm (verb)
To prepare a tool or a weapon for action; to activate.
“Remember to arm an alarm system.”
Arm (verb)
To cover or furnish with a plate, or with whatever will add strength, force, security, or efficiency.
“to arm the hit of a sword; to arm a hook in angling”
Arm (verb)
To furnish with means of defence; to prepare for resistance; to fortify, in a moral sense.
Arm (verb)
To fit (a magnet) with an armature.
Arm (adjective)
Poor; lacking in riches or wealth.
“He’s neither poor nor arm.”
Arm (adjective)
To be pitied; pitiful; wretched.
Forearm (noun)
The part of the arm between the wrist and the elbow.
Forearm (noun)
A section of the weapon between the receiver and the muzzle, used to hold the firearm steady.
Forearm (verb)
To arm in preparation.