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Forearm

 
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Forearm
 
 
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The forearm is the structure on the upper limb
Upper limb

In human anatomy, the upper Limb refers to what in common English is known as the arm, that is, the region of the shoulder to the fingertips....
, between the elbow and the wrist
Wrist

In human anatomy, the wrist is the flexible and narrower connection between the forearm and the hand. The wrist is essentially a double row of small short bones, called carpals, intertwined to form a malleable hinge....
.. This term is used in anatomy
Anatomy

Anatomy is a branch of biology that is the consideration of the body plan. It is a general term that includes human anatomy, animal anatomy and plant anatomy ....
 to distinguish it from the arm (or upper arm). It is homologous to the leg
Leg

Leg may refer to the following places in Poland:*A former name for the town of Elk *Leg, Lower Silesian Voivodeship *Leg, Kuyavian-Pomeranian Voivodeship ...
 that lies between the knee
Knee

----The knee is the lower extremity joint connecting the femur, patella, and the tibia and the surrounding anatomical region which includes the popliteal fossa, also known as "knee pit"....
 and the ankle
Ankle

In human anatomy, the ankle joint is formed where the foot and the human leg meet. The ankle, or talocrural joint, is a synovial hinge joint that connects the distal ends of the tibia and fibula in the lower limb with the proximal end of the talus bone in the foot....
 joints.

forearm contains two long bone
Bone

Bones are rigid organ that form part of the endoskeleton of vertebrates. They function to move, support, and protect the various organs of the body, produce red blood cell and white blood cells and store minerals....
s, the radius
Radius (bone)

The radius is the bone of the forearm that extends from the lateral side of the Elbow-joint to the thumb side of the wrist. The radius is situated on the lateral side of the ulna, which exceeds it in length and size....
 and the ulna
Ulna

The ulna is a long bone, prism atic in form, placed at the Anatomical terms of location#Relative directions side of the forearm, parallel with the radius ....
, forming the radioulnar joint. The interosseous membrane
Interosseous membrane

An interosseous membrane is a broad and thin plane of fibrous tissue that separates many of the bones of the body. It is an important component of many joints....
 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
Brachioradialis

Brachioradialis is a muscle of the forearm that acts to flex the forearm at the elbow. It is also capable of both pronation and supination, depending on the position of the forearm....
), and pronators and supinators that turn the hand to face down or upwards, respectively.






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The forearm is the structure on the upper limb
Upper limb

In human anatomy, the upper Limb refers to what in common English is known as the arm, that is, the region of the shoulder to the fingertips....
, between the elbow and the wrist
Wrist

In human anatomy, the wrist is the flexible and narrower connection between the forearm and the hand. The wrist is essentially a double row of small short bones, called carpals, intertwined to form a malleable hinge....
.. This term is used in anatomy
Anatomy

Anatomy is a branch of biology that is the consideration of the body plan. It is a general term that includes human anatomy, animal anatomy and plant anatomy ....
 to distinguish it from the arm (or upper arm). It is homologous to the leg
Leg

Leg may refer to the following places in Poland:*A former name for the town of Elk *Leg, Lower Silesian Voivodeship *Leg, Kuyavian-Pomeranian Voivodeship ...
 that lies between the knee
Knee

----The knee is the lower extremity joint connecting the femur, patella, and the tibia and the surrounding anatomical region which includes the popliteal fossa, also known as "knee pit"....
 and the ankle
Ankle

In human anatomy, the ankle joint is formed where the foot and the human leg meet. The ankle, or talocrural joint, is a synovial hinge joint that connects the distal ends of the tibia and fibula in the lower limb with the proximal end of the talus bone in the foot....
 joints.

The human forearm

The forearm contains two long bone
Bone

Bones are rigid organ that form part of the endoskeleton of vertebrates. They function to move, support, and protect the various organs of the body, produce red blood cell and white blood cells and store minerals....
s, the radius
Radius (bone)

The radius is the bone of the forearm that extends from the lateral side of the Elbow-joint to the thumb side of the wrist. The radius is situated on the lateral side of the ulna, which exceeds it in length and size....
 and the ulna
Ulna

The ulna is a long bone, prism atic in form, placed at the Anatomical terms of location#Relative directions side of the forearm, parallel with the radius ....
, forming the radioulnar joint. The interosseous membrane
Interosseous membrane

An interosseous membrane is a broad and thin plane of fibrous tissue that separates many of the bones of the body. It is an important component of many joints....
 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
Brachioradialis

Brachioradialis is a muscle of the forearm that acts to flex the forearm at the elbow. It is also capable of both pronation and supination, depending on the position of the forearm....
), 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 compartment
Fascial compartment

On the human body, the Limb s can be divided into segments, such as the arm and the forearm of the upper limb, and the thigh and the leg of the lower limb....
s. The posterior compartment contains the extensors of the hands, which are supplied by the radial nerve
Radial nerve

The radial nerve is a nerve in the human body that supplies the triceps brachii muscle of the arm, as well as all 12 muscles in the posterior osteofascial compartment of the forearm....
. The anterior compartment contains the flexors, and is mainly supplied by the median nerve
Median nerve

The median nerve is a nerve that runs down the arm and forearm. It is one of the five main nerves originating from the brachial plexus.The median nerve is formed from parts of the medial and lateral cords of the brachial plexus, and continues down the arm to enter the forearm with the brachial artery....
. The ulnar nerve
Ulnar nerve

In human anatomy, the ulnar nerve is a nerve which runs near the ulna bone. The ulnar nerve is the largest unprotected nerve in the human body , and the only unprotected nerve that does not serve a purely sensory function ....
 also runs the length of the forearm.

The radial
Radial artery

In human anatomy, the radial artery is the main blood vessel, with oxygenated blood, of the lateral aspect of the forearm....
 and ulnar arteries
Ulnar artery

The ulnar artery is the main blood vessel, with oxygenated blood, of the medial aspect of the forearm. It arises from the brachial artery and terminates in the superficial palmar arch, which joins with the superficial branch of the radial artery....
, 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
Cephalic vein

In human anatomy, the cephalic vein is a superficial vein of the upper limb.It communicates with the basilic vein via the median cubital vein at the Elbow-joint and is located in the superficial fascia along the anterolateral surface of the biceps brachii muscle....
, median antebrachial
Median antebrachial vein

The median antebrachial vein drains the venous plexus on the volar surface of the hand.It ascends on the ulnar side of the front of the forearm and ends in the basilic vein or in the vena mediana cubiti; in a small proportion of cases it divides into two branches, one of which joins the basilic, the other the cephalic, below the Elbow-joint...
 and the basilic vein
Basilic vein

In human anatomy, the basilic vein is a large superficial vein of the upper limb that helps drain parts of hand and forearm. It originates on the medial side of the dorsal venous network of the hand, and it travels up the base of the forearm and arm....
. These veins can be used for cannularisation or venipuncture
Venipuncture

In medicine venipuncture or venepuncture is the process of obtaining a sample of Vein blood. Usually a 5 ml to 25 ml sample of blood is adequate depending on what blood tests have been requested....
, although the cubital fossa
Cubital fossa

The cubital fossa is the triangular area on the anterior view of the elbow joint of the arm....
 is a preferred site for getting blood.

Anatomy


Bones

  • radius
    Radius (bone)

    The radius is the bone of the forearm that extends from the lateral side of the Elbow-joint to the thumb side of the wrist. The radius is situated on the lateral side of the ulna, which exceeds it in length and size....
  • ulna
    Ulna

    The ulna is a long bone, prism atic in form, placed at the Anatomical terms of location#Relative directions side of the forearm, parallel with the radius ....


Joints

  • proximal to forearm
    • elbow
  • in the forearm
    • proximal radioulnar joint
    • distal radioulnar joint
  • distal to forearm
    • wrist
      Wrist

      In human anatomy, the wrist is the flexible and narrower connection between the forearm and the hand. The wrist is essentially a double row of small short bones, called carpals, intertwined to form a malleable hinge....


Muscles


Compartment Level Muscle E/I Nerve >- | Anterior superficial flexor carpi radialis E - | Anterior superficial palmaris longus E - | Anterior superficial flexor carpi ulnaris E - | Anterior superficial pronator teres I - | Anterior superficial (or intermediate) flexor digitorum superficialis (sublimis) E - | Anterior deep flexor digitorum profundus E - | Anterior deep flexor pollicis longus E - | Anterior deep pronator quadratus
Pronator quadratus

Pronator quadratus is a square shaped muscle on the distal forearm that acts to pronate the hand.As it is on the anterior side of the arm, it is innervated by a branch of the median nerve, the anterior interosseous nerve ....
 		 I - | Posterior (see below) brachioradialis
Brachioradialis

Brachioradialis is a muscle of the forearm that acts to flex the forearm at the elbow. It is also capable of both pronation and supination, depending on the position of the forearm....
 		 I - | Posterior superficial extensor carpi radialis longus E - | Posterior superficial extensor carpi radialis brevis E - | Posterior intermediate extensor digitorum (communis) E - | Posterior intermediate extensor digiti minimi (proprius) E - | Posterior superficial extensor carpi ulnaris E - | Posterior deep abductor pollicis longus E - | Posterior deep extensor pollicis brevis E - | Posterior deep extensor pollicis longus E - | Posterior deep extensor indicis (proprius) E - | Posterior deep supinator I - | Posterior deep anconeus I radial


  • "E/I" refers to "extrinsic" or "intrinsic". The intrinsic muscles of the forearm act on the forearm, meaning, across the elbow joint and the proximal
    Proximal radioulnar articulation

    The proximal radioulnar articulation is a trochoid or pivot joint between the circumference of the head of the radius and the ring formed by the radial notch of the ulna and the annular ligament....
     and distal
    Distal radioulnar articulation

    The Distal Radioulnar Articulation is a pivot-joint formed between the head of the ulna and the ulnar notch on the distal radius....
     radioulnar joints (resulting in pronation
    Pronation

    In anatomy, pronation is a rotational movement of the forearm at the radioulnar joint, or of the foot at the subtalar joint and talocalcaneonavicular joints....
     or supination
    Supination

    Supination is a position of either the forearm or foot; in the forearm when the palm faces anteriorly, or faces up . Supination in the foot occurs when a person appears "Genu varum" with their weight supported primarily on the anterior of their feet....
    , whereas the extrinsic muscles 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
    Posterior compartment

    Posterior compartment can refer to:* Posterior compartment of the arm* Posterior compartment of the leg* rectum...
    , but it is actually in the anterior portion of the forearm.


Nerves

(See separate nerve articles for details on divisions proximal to the elbow and distal to the wrist; see Brachial plexus
Brachial plexus

The brachial plexus is an arrangement of nerve fibers, running from the spine, formed by the ventral rami of the lower cervical and upper thoracic nerve roots, specifically from above the fifth cervical vertebra to underneath the first thoracic vertebra ....
 for the origins of the median, radial and ulnar nerves)
  • Median nerve
    Median nerve

    The median nerve is a nerve that runs down the arm and forearm. It is one of the five main nerves originating from the brachial plexus.The median nerve is formed from parts of the medial and lateral cords of the brachial plexus, and continues down the arm to enter the forearm with the brachial artery....
     - principle nerve of the anterior compartment (PT, FCR, PL, FDS).
    • anterior interosseous nerve
      Anterior interosseous nerve

      The anterior interosseous nerve is a branch of the median nerve that supplies the deep muscles on the front of the forearm, except the ulnar half of the flexor digitorum profundus....
       (supplies FPL, lat. 1/2 of FDP, PQ
      Pronator quadratus

      Pronator quadratus is a square shaped muscle on the distal forearm that acts to pronate the hand.As it is on the anterior side of the arm, it is innervated by a branch of the median nerve, the anterior interosseous nerve ....
      ).
  • Radial nerve
    Radial nerve

    The radial nerve is a nerve in the human body that supplies the triceps brachii muscle of the arm, as well as all 12 muscles in the posterior osteofascial compartment of the forearm....
     - 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
    Ulnar nerve

    In human anatomy, the ulnar nerve is a nerve which runs near the ulna bone. The ulnar nerve is the largest unprotected nerve in the human body , and the only unprotected nerve that does not serve a purely sensory function ....
     - supplies some medial muscles (FCU, med. 1/2 of FDP).


Vessels

  • brachial artery
    Brachial artery

    The brachial artery is the major blood vessel of the upper arm.It is a continuation of the axillary artery beyond the lower margin of teres major muscle....
    • radial artery
      Radial artery

      In human anatomy, the radial artery is the main blood vessel, with oxygenated blood, of the lateral aspect of the forearm....
      • radial recurrent artery
        Radial recurrent artery

        The radial recurrent artery arises from the radial artery immediately below the Elbow-joint.It ascends between the branches of the radial nerve, lying on the Supinator and then between the Brachioradialis and Brachialis, supplying these muscles and the elbow-joint, and anastomosing with the terminal part of the profunda brachii....
    • ulnar artery
      Ulnar artery

      The ulnar artery is the main blood vessel, with oxygenated blood, of the medial aspect of the forearm. It arises from the brachial artery and terminates in the superficial palmar arch, which joins with the superficial branch of the radial artery....
      • pulmonary artery
        Pulmonary artery

        The pulmonary arteries carry blood from heart to the lungs. They are the only artery that carry deoxygenated blood.In the human heart, the pulmonary trunk begins at the base of the right ventricle....
      • anterior ulnar recurrent artery
        Anterior ulnar recurrent artery

        The anterior ulnar recurrent artery arises immediately below the elbow-joint, runs upward between the Brachialis and Pronator teres, supplies twigs to those muscles, and, in front of the medial epicondyle, anastomoses with the superior and inferior ulnar collateral arteries....
         and posterior ulnar recurrent artery
        Posterior ulnar recurrent artery

        The posterior ulnar recurrent artery is much larger than the anterior ulnar recurrent artery, and arises somewhat lower than it.It passes backward and medialward on the Flexor digitorum profundus, behind the Flexor digitorum sublimis, and ascends behind the medial epicondyle of the humerus....
      • common interosseous artery
        Common interosseous artery

        The common interosseous artery, about 1 cm. in length, arises immediately below the tuberosity of the radius from the Ulnar artery.Passing backward to the upper border of the interosseous membrane, it divides into two branches, the anterior interosseous artery and posterior interosseous artery arteries....
        • posterior interosseous artery
          Posterior interosseous artery

          The posterior interosseous artery is an artery of the forearm.It passes backward between the oblique cord and the upper border of the interosseous membrane....
        • anterior interosseous artery


Other structures

  • interosseous membrane of the forearm
    Interosseous membrane of the forearm

    The interosseous membrane of the forearm is a fibrous sheet that connects the radius and the ulna. It is the main part of the radio-ulnar syndesmosis, a fibrous joint between the two bones....
  • annular ligament
    Annular ligament

    The Annular Ligament is a strong band of fibers, which encircles the head of the radius, and retains it in contact with the radial notch of the ulna....
     of ulna


Additional images


Pathology


External links



See also

  • Forearm flexors
  • Forearm muscles