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Encyclopedia > Musculocutaneous nerve
Nerve: Musculocutaneous nerve
Nerves of the left upper extremity. (Musculocutaneous labeled at upper right.)
Latin nervus musculocutaneus
Gray's subject #210 935
Innervates anterior compartment of the arm
From lateral cord (C5-C7)
To lateral cutaneous nerve of forearm
Dorlands/Elsevier n_05/12566256

The musculocutaneous nerve arises from the lateral cord of the brachial plexus, opposite the lower border of the Pectoralis minor, its fibers being derived from the fifth, sixth, and seventh cervical nerves. Image File history File links Download high resolution version (524x1000, 162 KB) File links The following pages link to this file: Ulnar nerve Long thoracic nerve Wikipedia:Grays Anatomy images with missing articles 17 Musculocutaneous nerve List of images in Grays Anatomy: IX. Neurology ... Latin is an ancient Indo-European language originally spoken in Latium, the region immediately surrounding Rome. ... The anterior compartment of the arm is known as the flexor compartment as flexion is its main action. ... The Lateral cord is a division of the brachial plexus. ... The lateral antibrachial cutaneous nerve (or lateral cutaneous nerve of forearm) (branch of musculocutaneous nerve, also sometimes spelled antebrachial) passes behind the cephalic vein, and divides, opposite the elbow-joint, into a volar and a dorsal branch. ... Elseviers logo. ... The Lateral cord is a division of the brachial plexus. ... The brachial plexus is an arrangement of nerve fibres (a plexus) running from the spine (vertebrae C5-T1), through the neck, the axilla (armpit region), and into the arm. ... Location The pectoralis minor muscle takes its origin from the 3rd to 5th ribs, near their costal cartilages. ... The Cervical Nerves—The posterior division of the first cervical or suboccipital nerve is larger than the anterior division, and emerges above the posterior arch of the atlas and beneath the vertebral artery. ...

Contents

Path

It penetrates the Coracobrachialis muscle and passes obliquely between the Biceps brachii and the Brachialis, to the lateral side of the arm; a little above the elbow it pierces the deep fascia lateral to the tendon of the Biceps brachii and is continued into the forearm as the lateral antibrachial cutaneous nerve. Coracobrachialis is one of the three muscles that attach to the coracoid process of the scapula. ... A person flexing his biceps brachii In human anatomy, the biceps brachii is a muscle on the upper arm that acts to flex the elbow. ... Brachialis is a flexor muscle in the upper arm. ... The lateral antibrachial cutaneous nerve (branch of musculocutaneous nerve, also sometimes spelled antebrachial) passes behind the cephalic vein, and divides, opposite the elbow-joint, into a volar and a dorsal branch. ...


In its course through the arm it innervates the Coracobrachialis, Biceps brachii, and the greater part of the Brachialis.

  • The branch to the Coracobrachialis is given off from the nerve close to its origin, and in some instances as a separate filament from the lateral cord of the plexus; it is derived from the seventh, cervical nerve.
  • The branches to the Biceps brachii and Brachialis are given off after the musculocutaneous has pierced the Coracobrachialis; that supplying the Brachialis gives a filament to the elbow-joint.
  • The nerve also sends a small branch to the bone, which enters the nutrient foramen with the accompanying artery.

The Lateral cord is a division of the brachial plexus. ... Elbow redirects here. ...

Irregularities

The musculocutaneous nerve presents frequent irregularities.


It may adhere for some distance to the median and then pass outward, beneath the Biceps brachii, instead of through the Coracobrachialis.


Some of the fibers of the median may run for some distance in the musculocutaneous and then leave it to join their proper trunk; less frequently the reverse is the case, and the median sends a branch to join the musculocutaneous.


The nerve may pass under the Coracobrachialis or through the Biceps brachii.


Occasionally it gives a filament to the Pronator teres, and it supplies the dorsal surface of the thumb when the superficial branch of the radial nerve is absent. The Pronator teres muscle is a muscle of the human body, in the forearm. ...


Damage

Although rare, the musculocutaneous n. can be affected through compression due to hypertrophy or entrapment between the biceps aponeurosis & brachialis fascia or it may be injured through stretch as occurs in dislocations & sometimes in surgery. The Brachial Fascia (deep fascia of the arm) is continuous with that covering the Deltoideus and the Pectoralis major, by means of which it is attached, above, to the clavicle, acromion, and spine of the scapula; it forms a thin, loose, membranous sheath for the muscles of the arm, and...


Isolated injury, causes weakness of elbow flexion & supination of the forearm.


A discrete sensory disturbance is present on the radial side of the forearm.


The nerve is usually involved in an upper brachial plexus palsy


Injury can occur before entering the coracobrachialis due to dislocation or apparently due to stretch due to throwing injury


Heavy backpacks can cause damage to the upper trunk of the brachial plexus – dysfunction can be severe & prolonged with similar injury as occurs with Erb's palsy from breech deliveries. Early detection is important – the combination of time, avoidance of wearing a backpack, and strengthening of the shoulder muscles will probably be effective. Erbs Palsy, also known as Brachial Plexus Paralysis, is a condition which mainly due to birth trauma can affect 1 or all of the 5 primary nerves that supply the movement and feeling to an arm. ... Breech, by W.Smellie, 1792 A breech birth (also known as breech presentation) refers to the position of the baby in the uterus such that it will be delivered buttocks first as opposed to the normal head first position. ... A backpack A backpack is, in its simplest form, a cloth sack carried on ones back and secured with two straps that go over the shoulders (called shoulder straps) and below the armpits. ...


Distal to the coracobrachialis, the MC cause appears to be weight lifting – either through compression due to hypertrophy or entrapment between the biceps & brachialis, the nerve may lead to a painless loss of muscle strength in flexion & supination of the forearm. Initial treatment should include avoidance of biceps curls or other biceps exercises. Weightlifting is a sport where competitors attempt to lift heavy weights mounted on steel bars. ... Bodybuilder Markus Rühl has marked hypertrophy of skeletal muscle. ...


Initial treatment should include avoidance of biceps curls or other biceps exercises.


Additional images

External links

This article was originally based on an entry from a public domain edition of Gray's Anatomy. As such, some of the information contained herein may be outdated. Please edit the article if this is the case, and feel free to remove this notice when it is no longer relevant. Duke University is a private coeducational research university located in Durham, North Carolina, USA. Founded by Methodists and Quakers in the present-day town of Trinity in 1838, the school moved to Durham in 1892. ... eMedicine is an online clinical medical knowledge base that was founded in 1996. ... The University of Kansas (often referred to as KU) is an institution of higher learning in Lawrence, Kansas. ... Memorial University of Newfoundland, (popularly known as Memorial University or MUN) is a comprehensive university located primarily in St. ... The public domain comprises the body of all creative works and other knowledge—writing, artwork, music, science, inventions, and others—in which no person or organization has any proprietary interest. ... An illustration from the 1918 edition Henry Grays Anatomy of the Human Body, commonly known as Grays Anatomy after Henry Gray, is an anatomy textbook widely regarded as a classic work on human anatomy. ...


  Results from FactBites:
 
The Physician and Sportsmedicine: Bilateral Musculocutaneous Nerve Palsy From Strength Training (1398 words)
Musculocutaneous nerve palsy typically resolves when weight training routines are modified to reduce intensity and biceps curls are eliminated for at least 3 months.
The cause appears to be either nerve impingement because of hypertrophy of the brachioradialis muscle or a traction injury to the nerve from repetitive biceps curls.
One is a lesion of the musculocutaneous nerve before its division into the lateral cutaneous nerve that causes a mixed motor and sensory syndrome.
  More results at FactBites »

 
 

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