Forearm

The forearm (Latin foreleg ) is the lower portion of the upper extremity, so the arm between the elbow and wrist.

Bone

The forearm of humans ( and most other Tetrapoda ) consists of two long bones, the ulna ( ulna ) and the radius ( radius). Between the two bones is a gap ( antebrachial interosseous space ) through a band ( annular ligament of the radius ) and a fixed structure of connective tissue ( interosseous membrane ), the two bones are connected to each other.

Adjacent joints

The elbow joint ( articulatio cubiti ) is composed of three sub- joints pivot, which connects to the upper arm.

The wrist joint ( articulatio articulatio carpi or manus ) is a composite of two partial joints joint and connects the forearm to the hand (or paw forefoot or in animals ).

Joints

Between the two forearm bones themselves two joints are formed: The proximal ( proximal ) and distal ( distal ) ulnar joint ( radioulnar joint Proximal and distal radioulnar joint ). They allow rotational movement of the spoke to the ulna ( pronation and supination ). This rotation is especially important for complex movements (eg climbing, gripping). In mammals with predominantly running motion (eg, horses, ruminants) are the ulnar- joints regressed and the two bones fused together (called synostosis ).

Muscle and fascia

The muscles of the forearm are divided according to their position in two groups: the muscles that lie on the loosely hanging arm inside and thus the arm anbeugen ( flexors ) and the muscles that are on the outside and the arm straighten ( extensors ). These two groups each consisting of two individual layers, which go from the body surface into the depth.

The forearm ( antebrachial fascia ) borders the individual muscle bellies from one another. In addition, she shares with the band adhesion between the two forearm bones ( interosseous membrane ), enter the forearm muscles in a flexor and extensor one. In the area of the wrist it is reinforced on the back of the hand by transverse fibrous bands ( extensor retinaculum ). This gain serves as a holding device of the extensor tendons. On the palm side of the forearm fascia merges with the front fiber tows ( flexor retinaculum ) which form the carpal tunnel. From the biceps brachii is an additional reinforcement of the fascia ( Lacertus fibrosus ).

Arteries

The forearm blood can be for the most part by coming from the upper arm brachial artery ( brachial artery ). This bifurcates into the elbow in two vessel branches, which on its side spokes ( radial artery ) or Elle side ( ulnar artery ) run on hand.

The branches of the radial artery in the forearm are

• Radial recurrent artery ( declining radial artery )

The branches of the ulnar arteries in the forearm are

• Recurrent laryngeal nerve artery anterior and posterior ( front and rear declining ulnar arteries )
• Artery interosseous artery ( common interosseous artery) Anterior interosseous artery (anterior interosseous artery)
• Posterior interosseous artery ( posterior interosseous artery)

Veins

From the rear venous network of hand goes off on the spoke side of the outer vein ( cephalic vein ) and the ulna side the inner vein ( basilic vein ). Furthermore, the mean forearm vein ( vena intermedia antebrachial ) passes on the top front of the arm. In the elbow there is a connection between the outer and the inner vein, referred to collectively as the mean antecubital ( median cubital vein ). This is commonly used for intravenous injection or for blood sampling.

Bug

The innervation of the forearm muscles to be primarily originating from the brachial plexus fibers of the radial nerve, the median nerve and ulnar nerve.

The radial nerve innervates the muscles of the forearm back, the extensors and also the skin parts of the thumb and back of the hand. The median nerve innervates most of the muscles of the flexor and also the skin on the inside of the hand between the thumb and ring finger. The ulnar nerve innervates only the flexor carpi ulnaris and flexor digitorum profundus of the parts and also the skin on palm and back between ring finger and hand edge.

Injuries

A fraction of the spoke at the handle proximal end ( distal radius fracture) is 10 to 25 % of the most common fracture in the human body. It affects mostly young people through sports and work-related accidents or the elderly from falls. At a fraction of the ulna ( ulnar fracture ) in children is always to think of a Monteggia fracture ( fracture combination with dislocation of the radial head ). Therefore, not only an x-ray of the fracture area, but always the whole forearm with imaging of wrist and elbow joint must be made.