Anatomy Atlases(tm) : A digital library of anatomy information

Home | About | FAQ | Reviews | Search

Anatomy Atlases: Illustrated Encyclopedia of Human Anatomic Variation: Opus III: Nervous System: Plexuses: Brachial Plexus

Illustrated Encyclopedia of Human Anatomic Variation: Opus III: Nervous System: Plexuses

Brachial Plexus

Ronald A. Bergman, PhD
Adel K. Afifi, MD, MS
Ryosuke Miyauchi, MD

Peer Review Status: Internally Peer Reviewed


The brachial plexus is formed by the anterior primary divisions of the lower four cervical nerves and the greater part of the anterior primary division of the first thoracic nerve. It may be joined by branches from the fourth cervical and the second thoracic nerves.

In one study of 175 plexuses, more than 60% received a communication from the fourth cervical nerve. Of those that did not receive a contribution from the fourth, almost 30% of the 175 plexuses studied received the entire anterior primary division of the fifth cervical. In the remaining 10%, a portion of the fifth cervical contributed to the cervical plexus.

The brachial plexus was bilaterally symmetrical in 61.9% of 63 cadavers.

Brachial plexuses receiving a branch from the fourth cervical nerve are more cephalic with reference to the vertebral column and have been designated as high or prefixed. Those receiving the largest part of the fifth cervical nerve are more caudal with reference to the vertebral column and have been designated as low or postfixed brachial plexuses.

The following variations in the organization or course of components of this plexus have been reported. The fifth cervical nerve may pass in front of or through the anterior scalene muscle.

The sixth cervical nerve may cross the anterior scalene. The seventh cervical nerve (as the middle trunk) may break up into three branches (instead of the usual two), one branch going to each of the three cords.

Occasionally the fibers of the posterior cord may arise from only the the seventh and eighth cervical nerves.

The first thoracic may fail to contribute to the posterior cord or may be the sole source of the medial cord.

Instead of the usual three cords, only two cords, a smaller and a larger, may be present. In such cases, the larger cord will replace either the medial and lateral or the medial and posterior cords.

Cases of a single cord have been reported.

A prefixed (high) type of brachial plexus exists in which the fourth cervical nerve contributes a fairly large branch, the dorsal branch of the first thoracic nerve is small, and there is no ascending branch from the second thoracic nerve. A postfixed (low) type of plexus is occasionally encountered in which the branch from the fourth cervical nerve is absent, the dorsal branch of the first thoracic is large, and the second thoracic nerve supplies a branch to the plexus.

In humans the brachial plexus is prefixed when compared to that in all primates below the anthropoids.

The variations in this plexus may be appreciated by examining the illustrations that accompanied this text. The memorization of a textbook drawing of the brachial plexus, for testing purposes, is without merit. It would be more meaningful to teach the significance of the plexus and its permutations.

Image 31A Image 31B Image 31C Image 31D Image 31E Image 31F

Image 31G Image 31H Image 31I Image 31J Image 32A Image 32B Image 32C Image 32D Image 32E Image 32F Image 33A

Image 33B Image 33C Image 34A Image 34B Image 35A

Image 35B Image 35C Image 36


References

Billet, H. (1933) Les troncs primaires du plexus brachial. Assoc. Anatomistes Comptes Rendus 28:63-71.

Billet, H. (1937) Suite de l'étude des rapports des branches collaterales de la souclaviere avec les troncs primaires de plexus brachial. Assoc. Anatomistes Comptes Rendus 32:49-52.

Brooks, W.T. (1883) The brachial plexus of the macaque monkey and its analogy with that of man. J. Anat. Physiol. 17:329-332.

Bumke, O. and O. Förster. (1935) Handbuch der Neurologie, Vol. I., Springer Verlag., Berlin.

Chetrick, A. and L.R.M. del Guercio (1951) Unusual brachial plexus formation. Yale J. Biol. Med. 23:395-398.

Clara, M. (1959) Das Nervensystem des Menschen. Barth., Leipzig.

Cruveilhier, J. (1851) Traité d'Anatomie Descriptive, 3rd ed., G. Doin & Cie., Paris.

Cunningham, D.J. (1909) Textbook of Anatomy, 3rd ed., Oxford University Press., London, New York.

Curnow, J. (1873) Notes of some irregularities in muscles and nerves. J. Anat. Physiol. 7:304-310.

Demarquay, -. (1844) Disposition anormale du plexus brachial. Muscles scalènes. Bulletins et Mem. de la Société Anatomique de Paris XIX(3):78.

Deville, -. (1849) Passage du deux nerfs du plexus brachial à travers deux veines perforées, axillaire et un petite veine non-denommee. Bulletins et Mem. de la Société Anatomique de Paris XXIV(1):8.

Dow, D.R. (1925) The anatomy of rudimentary first thoracic ribs, with special reference to the arrangement of the brachial plexus. J. Anat. 59:166-179.

Eisler, P. (1893) Grundriss der Anatomie des Menschen. Enke, Stuttgart.

Fenart, R. (1958) La morphogenese du plexus brachial, ses rapports avec la formation du cou et due membre superieur. Acta Anat. 32:322-360.

Forssmann, W.G. and C. Heym. (1944) Neuroanatomie, 4. Aufl., Springer Verlag, Berlin.

Harris, W. (1904) The true form of the brachial plexus, and its motor distribution. J. Anat. Physiol. 38:399-422.

Hasan, M. and D. Narayan. (1964) A single cord human brachial plexus. J. Anat. Soc. India 13:103-104.

Henle, J. (1868) Handbuch der Systematischen Anatomie des Menschen. von Friedrich Vieweg und Sohn, Braunschweig.

Hirasawa, K. (1931) Arbeiten aus der dritten Abteilung des Anatomischen Institutes der Kaiserlichen Universität Kyoto, Series A: Untersuchungen über das periphere Nervensystem. Buch 2: Plexus brachialis und die Nerven der oberen Extremität. Kyoto.

Hirschfeld, L. and J.B. Leveillé (1853) Névrologie ou description et icongraphie du system nerveaux et des organes des sens de 11 homme avec leur mode de préparation.

Kerr, A.T. (1918) The brachial plexus of nerves in man, the variations in its formation and branches. Am. J. Anat. 23:285-395.

Latarjet, A. (1948) Testut's Traité d'Anatomie Humaine, 9th ed., G. Doin & Cie., Paris.

Lazorthes, G. (1955) Le système nerveux périphérique. Masson., Paris.

Linell, E.A. (1921) The distribution of nerves in the upper limb, with reference to variabilities and their clinical significance. J. Anat. 55:79-112.

Miller, R.A. (1939) Observations upon the arrangement of the axillary artery and the brachial plexus. Am. J. Anat. 64:143-163.

Monro, A (1783) Observations on the structure and functions of the nervous system. Creech., Edinburgh

Poirier, P. and A. Charpy. (1901) Traité d'Anatomy Humaine, 2nd ed., vol. 3., Masson, Paris.

Sappey, P.C. (1871) Traité d'Anatomie Descriptive, 2nd ed., Delahaye, Paris.

Scott, S. (1906) A record of decussations of the brachial plexus in man. J. Anat. Physiol. 40:412-415.

Schaefer, E.A., Symington, J. and T.H. Bryce., Eds. (1915) Quain'Anatomy, 11th ed., Longmans, Green, and Co., London.

Sieglbauer, F. (1930) Lehrbuch der normalen Anatomie des Menschen, 2 Aufl., Urban & Schwarzenberg, Berlin.

Singer, E. (1934) Human brachial plexus united into a single cord. Description and interpretation. Anat. Rec. 55:411-419.

Smith, G.E. (1904) A note on the communication between the musculospiral and ulnar nerves. J. Anat. 38:162-163.

Tandler, J. (1929) Lehrbuch der Systematischen Anatomie., vol. 4., Vogel, Leipzig.

Turner, W. (1872) Some additional variations in the distribution of the nerves of the human body. J. Anat. Physiol. 6:101-106.

Wachtler, F. (1978) Eine seltene Varietät im Gefäss-Nervenbündel der axilla. Anat. Anz. 143:450-455.

Walsh, J.F. (1877) The anatomy of the brachial plexus. Am. J. Med. Sci. 74:388-399.

Williams, P.L. and R. Warwick. (1980) Gray's Anatomy, 36th ed., Curchill Livingstone, Edinburgh.

Section Top | Title Page
Home | About Us | FAQ | Reviews | Contact Us | Search

Anatomy Atlases is curated by Michael P. D'Alessandro, M.D. and Ronald A. Bergman, Ph.D.

Please send us comments by filling out our Comment Form.

All contents copyright © 1995-2017 the Author(s) and Michael P. D'Alessandro, M.D. All rights reserved.

"Anatomy Atlases", the Anatomy Atlases logo, and "A digital library of anatomy information" are all Trademarks of Michael P. D'Alessandro, M.D.

Anatomy Atlases is funded in whole by Michael P. D'Alessandro, M.D. Advertising is not accepted.

Your personal information remains confidential and is not sold, leased, or given to any third party be they reliable or not.

The information contained in Anatomy Atlases is not a substitute for the medical care and advice of your physician. There may be variations in treatment that your physician may recommend based on individual facts and circumstances.

URL: http://www.anatomyatlases.org/