Radial Nerve

Information about Radial Nerve

*Nerve:*

The suprascapular, axillary, and radial nerves.
Latin	nervus radialis
	subject #210 943
Innervates	posterior compartment of the arm, posterior compartment of the forearm
From	posterior cord
To	posterior interosseous nerve
MeSH	Radial+Nerve
Dorlands/Elsevier	n_05/12566581

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.

It originates from the posterior cord of the brachial plexus with roots from C5, 6, 7, 8, & T1.

The radial nerve and its branches supply the dorsal muscles, such as triceps brachii, the extrinsic extensors of the wrist and hands, and the cutaneous nerve supply to most of the back of the hand. (The ulnar nerve cutaneously innervates the back of the little finger.)

The radial nerve divides into a deep branch, (which becomes the posterior interosseous nerve), and continues as the superficial branch which goes on to innervate the dorsum (back) of the hand.

Course

The radial nerve originates as a terminal branch of the posterior cord of the brachial plexus.

Posterior

From the brachial plexus, it travels posteriorly through what often called the triangular interval (US) or lower triangular space (UK).

The radial nerve enters the arm behind the axillary artery/brachial artery, and it then travels posteriorly on the medial side of the arm.

After giving off branches to the long and lateral heads of the triceps brachii, it enters a groove on the humerus, the radial sulcus.

Along with the deep brachial artery, the radial nerve winds around in the groove (between the medial and lateral heads of the triceps) towards the forearm, running laterally on the posterior aspect of the humerus.

While in the groove, it gives off a branch to the medial head of the triceps brachii.

The radial nerve emerges from the groove on the lateral aspect of the humerus.

At this point, it pierces the lateral intermuscular septum and enters the anterior compartment of the arm.

It continues its journey inferiorly between the brachialis and brachioradialis muscles.

When the radial nerve reaches the distal part of the humerus, it passes in front of the lateral epicondyle.

It then branches into a superficial branch (primarily sensory) and a deep branch (primarily motor).

The superficial branch of the radial nerve descends in the forearm under the brachioradialis. It eventually pierces the deep fascia near the back of the wrist.
The deep branch of the radial nerve pierces the supinator muscle, after which it is known as the posterior interosseous nerve.

Branches/Innervations

The following are branches/innervations of the radial nerve (including the superficial branch of the radial nerve and the deep branch of the radial nerve/posterior interosseous nerve).

Cutaneous

Cutaneous innervation is provided by the following nerves:

Posterior cutaneous nerve of arm (originates in axilla)
Inferior lateral cutaneous nerve of arm (originates in arm)
Posterior cutaneous nerve of forearm (originates in arm)

The superficial branch of the radial nerve provides sensory innervation to much of the back of the hand, including the web of skin between the thumb and index finger.

Motor

Muscular branches of the radial nerve:

Deep branch of the radial nerve:

Posterior interosseous nerve (a continuation of the deep branch after the supinator):

The radial nerve (and its deep branch) provides motor innervation to the muscles in the posterior compartment of the arm and forearm, which are mostly extensors.

Additional images

Brachial plexus	Cross-section through the middle of upper arm.	Cross-section through the middle of the forearm.	The brachial artery.
Suprascapular and axillary nerves of right side, seen from behind.	Cutaneous nerves of right upper extremity. Posterior view.	Diagram of segmental distribution of the cutaneous nerves of the right upper extremity. Posterior view.	Superficial palmar nerves.
Nerves of the left upper extremity.	Deep palmar nerves.	Front of right upper extremity, showing surface markings for bones, arteries, and nerves.	Back of right upper extremity, showing surface markings for bones and nerves.

External links

Duke Orthopedics radial_nerve
Atlas of anatomy at UMich hand_plexus - "Axilla, dissection, anterior view"

• • [ e] Nerves of upper limbs (primarily): the brachial plexus
Supraclavicular	dorsal scapular • suprascapular • to the subclavius • long thoracic
Infraclavicular: lateral cord	musculocutaneous (lateral cutaneous of forearm) • lateral pectoral • lateral head of median (anterior interosseous, palmar, common palmar digital, proper palmar digital)
Infraclavicular: medial cord	medial pectoral • medial cutaneous of forearm • medial cutaneous of arm • ulnar (muscular branches, dorsal branch, palmar branch, superficial branch, deep branch) • medial head of median
Infraclavicular: posterior cord	subscapular (upper, lower) • thoracodorsal • axillary (superior lateral cutaneous of arm) • radial (muscular, inferior lateral cutaneous of arm, posterior cutaneous of arm, posterior cutaneous of forearm, superficial branch, deep branch, posterior interosseous)
Other	cutaneous innervation of the upper limbs

The suprascapular nerve arises from the trunk formed by the union of the fifth and sixth cervical nerves. It innervates the supraspinatus muscles and infraspinatus muscles.
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The axillary nerve is a nerve of the human body, that comes off the posterior cord of the brachial plexus at the level of the axilla (armpit) and carries nerve fibers from C5 and C6.
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Latin}}}
Official status
Official language of: Vatican City
Used for official purposes, but not spoken in everyday speech
Regulated by: Opus Fundatum Latinitas
Roman Catholic Church
Language codes
ISO 639-1: la
ISO 639-2: lat
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The posterior compartment of the arm contains muscles which are all supplied by the radial nerve. This compartment is also known as the "extensor compartment", extension being its main action.

The muscles of this compartment are the triceps brachii and anconeus muscle.
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The posterior compartment of the forearm contains the following muscles:

Level Muscle E/I
(see below) brachioradialis I
superficial extensor carpi radialis longus E
superficial extensor carpi radialis brevis E
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The posterior cord is a division of the brachial plexus. It consists of contributions from all of the roots of the brachial plexus.^[1]

The posterior cord gives rise to the following nerves:^[2]

Name Roots Supplies
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posterior interosseous nerve (or dorsal interosseous nerve), on the interosseous membrane, in front of the Extensor pollicis longus, to the back of the carpus, where it presents a gangliform enlargement from which filaments are distributed to the ligaments and articulations
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Medical Subject Headings (MeSH) is a huge controlled vocabulary (or metadata system) for the purpose of indexing journal articles and books in the life sciences. Created and updated by the United States National Library of Medicine (NLM), it is used by the MEDLINE/PubMed
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Elsevier, the world's largest publisher of medical and scientific literature, forms part of the Reed Elsevier group. Based in Amsterdam, the company has substantial operations in the UK, USA and elsewhere.
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A nerve is an enclosed, cable-like bundle of axons (the long, slender projection of a neuron). Neurons are sometimes called nerve cells, though this term is technically imprecise since many neurons do not form nerves, and nerves also include the glial cells that
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The brachial plexus is an arrangement of nerve fibres, running from the spine, specifically from above the fifth cervical vertebra to underneath the first thoracic vertebra (C5-T1). It proceeds through the neck, the axilla (armpit region) and into the arm.
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The triceps brachii muscle is often simply called the triceps (both singular and plural). However, the term triceps (Latin for "three-headed") can mean any skeletal muscle having three origins.
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In human anatomy, the ulnar nerve is a nerve which runs from the shoulder to the hand, at one part running near the ulna bone. It is the only exposed nerve in the human body (it is unprotected for a few centimeters at the elbow).
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The triangular interval is the space between the long head of the triceps brachii and the humerus, just inferior to the teres major.

The radial nerve and profunda brachii pass through the triangular interval.
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In human anatomy, the axillary artery is a large blood vessel that conveys oxygenated blood to the lateral aspect of the thorax, the axilla (armpit) and the upper limb. Its origin is at the lateral margin of the first rib, before which it is called the subclavian artery.
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The brachial artery is the major blood vessel of the upper arm.

It is a continuation of the axillary artery and it originates from the lower margin of teres major muscle and continues down the arm, until it reaches the cubital fossa at the elbow.
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The radial sulcus is a groove for the radial nerve on the humerus bone.

The center of the lateral border of the humerus is traversed by a broad but shallow oblique depression, the radial sulcus (musculospiral groove, radial groove, spiral groove).
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The arteria profunda brachii (also known as deep artery of the arm) is a large vessel which arises from the medial and back part of the brachial, just below the lower border of the Teres major.
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The lateral intermuscular septum extends from the lower part of the crest of the greater tubercle of the humerus, along the lateral supracondylar ridge, to the lateral epicondyle; it is blended with the tendon of the Deltoideus, gives attachment to the Triceps brachii behind, to
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The anterior compartment of the arm is known as the "flexor compartment" as flexion is its main action.

The muscles contained therein are the biceps brachii, brachialis, and coracobrachialis.
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The brachialis (brachialis anticus) is a muscle in the upper arm that flexes the elbow joint. It lies just deep to biceps brachii, and is a more powerful flexor of the elbow. It makes up part of the floor of the region known as the cubital fossa.
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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.
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The lower extremity of the humerus is flattened from before backward, and curved slightly forward; it ends below in a broad, articular surface, which is divided into two parts by a slight ridge.

Projecting on either side are the lateral and medial epicondyles.
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Lateral epicondyle can refer to:

Lateral epicondyle of the humerus (dorsal epicondyle in birds)
Lateral epicondyle of the femur

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The superficial branch of the radial nerve passes along the front of the radial side of the forearm to the commencement of its lower third.

It lies at first slightly lateral to the radial artery, concealed beneath the Brachioradialis.
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