In this chapter, the authors present the most common arrangement of the
brachial plexus; its five roots of origin, three trunks, anterior and posterior divisions, three
cords, and, finally, its terminal branches. The sensory dermatomal and osteotomal
innervation of the spinal roots are discussed, as well as the neurotomal distribution of each
peripheral terminal branch. Anatomical dissections of the lateral view of the neck and its
posterior triangle are presented, as well as trans-sectional anatomical views at the level of
the 6th cervical vertebra. Photographs of anatomical dissections of the five scalene muscles
are discussed, especially the crossover of the fibers of the anterior and middle scalene
muscles, which forms the paravertebral trough, and the seven most commonly found
positional anomalies of the muscles with the roots of the cervical ventral rami. Finally,
multiple anatomic sagittal sections of the neck, starting from the spine and ending at the
mid-clavicular line, show the supraclavicular brachial plexus. These multiple sections are
presented in the form of three figures of strategic positions, and also as a movie where these
multiple sections have been added together to play sequentially. The authors discuss the
innervation of the five joints around the shoulder girdle in some detail in this chapter.
Keywords: Anterior scalene muscle, Brachial plexus, Cervical paravertebral
space, Dermatomes, Dorsal middle scalene muscle, Dorsal scapular nerve,
Inferior trunk, Long thoracic nerve, Middle trunk Cords, Nerve to levator
scapulae, Neurotomes, Osteotomes, Phrenic nerve, Posterior scalene muscle,
Scalene minimi muscle, Shoulder joint innervation, Spinal accessory nerve,
Spinal roots, Superior trunk, Suprascapular nerve, Ventral middle scalene muscle.
