SCALENE MUSCLES 353 



BURS^ 



The bursa m. sterno-hyoidei is in constantly found between the lower margin of the hyoid 

 bone and median hyo-thyreoid ligament and the sterno-hyoid muscle and external cervical 

 fascia. It is better developed in men than in women and is found either on each side of the 

 median line or fused in the median line. 



The bursa m. thyreo-hyoidei is frequently found between the greater cornu of the hyoid 

 bone and hyo-thyreoid membrane and the thyreo-hyoid muscle. 



7. SCALENE MUSCULATURE 



(Figs. 348 and 352) 



The three muscles which form this group constitute a triangular mass which 

 extends in front of the levator scapulae and intrinsic dorsal musculature and ^ 

 behind the prevertebral musculature from the first two ribs to the transverse (^ 

 processes of the cervical vertebrae. They cover lateral^ the apex of the pleural 

 cavity. The}'' bend the neck and fix the first two ribs or raise the thorax. In 

 front lies the scalenus anterior, which extends from the first rib to the fourth to 

 sixth vertebrae. Behind this the scalenus medius extends from the first rib to the 

 lower six vertebrae. The most dorsal of the group, the scalenus posterior, 

 extends from the second rib to the fifth and sixth vertebrae. 



These muscles are supplied by direct branches of the cervical nerves. They are probably 

 derived from the lateral portions of the cervical myotomes. According to Gegenbaur, the two 

 more ventral are homologous with intercostal muscles, the dorsal with the levatores costarum. 

 It is to be noted, however, that the anterior muscle lies in front of the brachial plexus, i. e., in 

 a position similar to that of the subcostal musculature. The scalene musculature is morpho- 

 logically closely related to the deep shoulder-gu-dle musculature, p. 356. 



FASCIA 



(Figs. 351, 357) 



From the front of the bodies of the cervical vertebrae the prevertebral fascia is continued 

 laterally over the longus colli and the scalene muscles, and extends dorsally into the fascia 

 covering the levator scapulae. Between the muscles fascial processes are sent in to become 

 attached to the cervical vertebrae. Inferiorly the fascia extends to the outer surface of the thorax. 



MUSCLES 



(Fig. 352) 



The scalenus anterior. — This arises from the ventral part of the inferior border of the 

 transverse processes of the fourth, fifth, and sixth cervical vertebrae, usually also from the third, 

 rarely from the seventh, by means of long, slender tendinous processes. From each tendon 

 arises a fasciculus composed of nearly parallel fibre-bundles. The fasciculi soon fuse to form a 

 muscle belly which contracts somewhat toward the insertion. This takes place by means of 



1. Arteria carotis communis. 2a. A. cervicalis profunda. 26. A. cervicahs superficialis 

 3. A. thoracoacromialis (acromial branch). 4a. A. thyreoidea inferior. 46. A. thyreoidea 

 superior. 5. A. transversa colli. 6. A. transversa scapulae. 7. A. vertebrahs. 8. Bursa 

 m. subscapuiaris. 9. Cartilage arytenoidea. 10. Cartilago thyreoidea. 11. Clavicle. 

 12. Costa I. 13. Costa II. 14. Fascia cervicahs — a, superficial layer; 6, middle layer. 

 15. Deep or prevertebral layer. 16. Fascia coraco clavicularis. 17. Fascia nuchae. 

 18. Glandula thj^eoidea. 19. Humerus. 20. Ligamentum coracohumerale. 21. Med- 

 ulla spinalis (spinal cord). 22. Musculus arytenoideus transversus. 23. M. biceps brachii, 

 tendon long head. 24. M. constrictor pharyngis inferior. 25. M. deltoideus. 26. M. 

 Uio-costahs. 27. M. infraspinatus. 28. M. levator scapulae. 29. M. longissimus capitis 

 (trachelo-mastoid). 30. M. longissimus cervicis. 31a. M. longus colh. 316. M. longus 

 capitis (rectus capitis anticus major). 32. M. omo-hyoideus. 33. M. platysma. 34. M. 

 rhomboideus minor. 35. M. scalenus anterior. 36. M. scalenus medius. 37. M. semi' 

 spinalis capitis (complexus). 38. M. serratus anterior. 39. M. serratus posterior superior. 

 40. M. splenius. 41. M. sterno-cleido-mastoideus. 42. M. sterno-hj^oideus. 43. M. 

 sterno-thyreoideus. 44. M. subclavius. 45. M. subscapuiaris; a, tendon. 46. M. 

 thyreo-arytenoideus (and vocalis). 47. M. thyreo-hyoideus. 48. M. transverso-spinales. 

 49. M. trapezius. 50. Nervous accessorius. 51. N. cervicalis IV. 52. N. laryngeus 

 inferior. 53. N. descendens hypoglossi. 54. Sympathetic trunk. 55. N. thoracaUs I. 

 56. N. vagus. 57. (Esophagus. 58. Plexus brachialis. 59. Scapula — a, glenoid cavity; 

 6, coracoid process; c, spine. 60. Trachea. 61. Vena transversa coUi. 62. V. jugularis 

 externa. 63. V. jugularis interna. 64. Vertebra cervicahs V. 65. Vertebra cervicalis 

 VII. 66. Vertebra thoracalis I, arch. 67. Vertebra thoracalis II — a, spine; 6, transverse 

 process. 



23 



