Complexus Rectus capitis anticus minor Flexor capitis inferior Rectus capitis posticus major Biventer cervicis Longus colli posticus Obliquus colli Longus colli anterior Rectus capitis lateralis Trachelo-mastoideus Interspinales Interarticulares Obliquo-transversales Intertransversales Scalenus medius =Complexus= (Fig. 19, No. 5). _Location._—Supero-lateral portion of the neck. _Origin._—By three tendinous slips from the antero-lateral portion of the transverse process of the fourth, the fifth, and the sixth cervical vertebræ. _Insertion._—The muscular fibers pass around the neck and meet their fellows in the median line in a fascia formation. The thin tendinous sheet inserts into the occiput just above the occipital ridge. _Shape._—From point of origin this muscle expands into a broad sheet. _Relations._—It overlies the muscles of the occipital region. _Action._—It extends the head. =Rectus Capitis Anticus Minor= (Fig. 19, No. 8). (Synonym.—Rectus capitis ventralis minor.) _Location._—Infero-lateral portion of the neck. _Origin._—From the apices of the hyapophyses of the second, the third, and the fourth cervical vertebræ. _Insertion._—To the occiput just below the complexus. _Shape._—A long and rather thick fasciculus. _Relations._—Externally with the skin. The tendinous slips of origin pass between the flexor capitis inferior and longus colli anterior. _Action._—Extends the head. =Flexor Capitis Inferior= (Fig. 19, No. 7). _Location._—Antero-inferior part of the neck. _Origin._—From the apices of the hyapophyses of the second, the third, and the fourth cervical vertebræ. _Insertion._—To the triangular area on the basi-temporal of the base of the cranium. _Shape._—At first tendinous, becomes somewhat fleshy as it passes forward. [Illustration: FIG. 19.—Muscles of the head and neck. 1, Masseter muscle. 2, Infraorbital sinus. 3, Biventer maxilla. 4, Temporalis. 5, Complexus. 6, Rectus capitis posticus major. 7, Flexor capitis inferior. 8, Rectus capitis anticus minor. 9, Biventer cervicis. 10, Longus colli posticus. 11, Obliquus colli. 12, Intertransversales. 13, Longus colli anterior. 14, Lateral temporo-maxillary ligament. 15, Lateral ligament of the jaw. 16, Trachelo-mastoideus. 17, Rectus capitis lateralis. 18, Scalenus medius. 19, Rhomboideus. 20, Trapezius. 21, Location of scapula. 22, Supraspinatus. 23, Teres et Infraspinatus. ] _Relations._—Antero-inferior portion of the neck close to the rectus capitis anticus minor. _Action._—Flexes the head upon the neck. =Rectus Capitis Posticus Major= (Fig. 19, No. 6). (Synonym.—Rectus capitis dorsalis major.)