Rhomboid muscles | Adductor muscles of the hip | ''Spiral Expansion of Muscles in Action'', plaster, photograph published in 1914 and 1919, in ''Cubists and Post-Impressionism'', by Arthur Jerome Eddy | Epaxial and hypaxial muscles | Color plate by Jacques Gautier d'Agoty, showing some of the muscles of the head. Part of a series of illustrations from Myologie complete en couleur et grandeur naturelle (1746) with texts by French physician and anatomist Guichard Joseph Duverney |
The medial tract has a "straight" (interspinales, intertransversarii, and spinalis) and an "oblique" (multifidus and semispinalis) component, both of which stretch between vertebral processes; the former acts similar to the muscles of the lateral tract, while the latter function unilaterally as spine extensors and bilaterally as spine rotators.