Forearm
From Wikipedia, the free encyclopedia
| Forearm | |
|---|---|
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| The forearm is the part of the arm between the elbow and the wrist. | |
| Latin | antebrachium |
| MeSH | Forearm |
| Dorlands/Elsevier | a_45/12138967 |
The forearm is the structure on the upper limb, between the elbow and the wrist.[1]. This term is used in anatomy to distinguish it from the arm (or upper arm).
Contents |
[edit] The human forearm
The forearm contains two long bones, the radius and the ulna, which form the radioulnar joint. These bones are connected by the interosseous membrane. 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 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.
[edit] Anatomy
[edit] Bones
[edit] Joints
- proximal to forearm
- in the forearm
- distal to forearm
[edit] Muscles
| Compartment | Level | Muscle | E/I | Nerve |
| Anterior | superficial | flexor carpi radialis | E | median |
| Anterior | superficial | palmaris longus | E | median |
| Anterior | superficial | flexor carpi ulnaris | E | ulnar |
| Anterior | superficial | pronator teres | I | median |
| Anterior | superficial (or intermediate) | flexor digitorum superficialis (sublimis) | E | median |
| Anterior | deep | flexor digitorum profundus | E | ulnar + median |
| Anterior | deep | flexor pollicis longus | E | median |
| Anterior | deep | pronator quadratus | I | median |
| Posterior | (see below) | brachioradialis | I | radial |
| Posterior | superficial | extensor carpi radialis longus | E | radial |
| Posterior | superficial | extensor carpi radialis brevis | E | radial |
| Posterior | intermediate | extensor digitorum (communis) | E | radial |
| Posterior | intermediate | extensor digiti minimi (proprius) | E | radial |
| Posterior | superficial | extensor carpi ulnaris | E | radial |
| Posterior | deep | abductor pollicis longus | E | radial |
| Posterior | deep | extensor pollicis brevis | E | radial |
| Posterior | deep | extensor pollicis longus | E | radial |
| Posterior | deep | extensor indicis (proprius) | E | radial |
| Posterior | deep | supinator | I | radial |
| Posterior | deep | anconeus | I | radial |
- "E/I" refers to "extrinsic" or "intrinsic". In most cases, the extrinsic anterior muscles are flexors of the hand and wrist. The extrinsic muscles of the forearm act upon the hand and wrist. In most cases, the extrinsic anterior muscles are flexors, while the extrinsic posterior muscles are extensors.
- The Brachioradialis, flexor of the forearm, is unusual in that it is located in the posterior compartment, but it is actually in the anterior portion of the forearm.
[edit] Nerves
(See separate nerve articles for details on divisions proximal to the elbow and distal to the wrist; see Brachial plexus for the origins of the median, radial and ulnar nerves)
- Median nerve - principle nerve of the anterior compartment (PT, FCR, PL, FDS).
- anterior interosseous nerve (supplies FPL, lat. 1/2 of FDP, PQ).
- Radial nerve - supplies muscles of the posterior compartment (ECRL, ECRB).
- Superficial branch of radial nerve
- Deep branch of radial nerve, becomes Posterior interosseus nerve and supplies muscles of the posterior compartment (ED, EDM, ECU, APL, EPB, EPL, EI).
- Ulnar nerve - supplies some medial muscles (FCU, med. 1/2 of FDP).
[edit] Vessels
(see separate vessel articles for branches distal to the wrist)
[edit] Other structures
[edit] Additional images
 Superficial muscles of the forearm |
 Deep muscles of the forearm |
 Cross-section through the middle of the forearm. |
[edit] References
[edit] External links
HEAD: Skull - Forehead – Eye – Ear – Nose – Mouth – Tongue – Teeth – Jaw – Face – Cheek – Chin
NECK: Throat – Adam's apple - Larynx
TORSO: Shoulders – Spine – Chest – Breast – Ribcage – Abdomen – Navel
LIMBS: Arm – Elbow – Forearm – Wrist – Hand – Finger (Thumb/Index/Middle/Ring/Little) – Leg – Lap – Thigh – Knee – Calf – Heel – Ankle – Foot – Toe (Hallux)
