FASCLE OF THE TRUiN'K. 265 



also forms sheaths for the other muscles of the neck over which it passes 

 If the superficial layer of the sheath of the sterno-mastoid be traced up- 

 wards, it will be found to pass over the parotid gland and masseter muscle, 

 and to be inserted into the zygomatic 

 arch ; and if it be traced downwards, it 

 will be seen to pass in front of the clavi- 

 cle, and become lost upon the pectoralis 

 major muscle. If the deep layer of the 

 sheath be examined superiorly, it will be 

 found attached to the styloid process, 

 from which it is reflected to the angle of 

 the lower jaw, forming the stylo- maxil- 

 lary ligament; and if it be followed 

 downwards, it will be found connected 

 with the tendon of the omo-hyoid mus- 

 cle, and may thence be traced behind 

 the clavicle, where it encloses the sub- 

 clavius muscle, and, being extended 

 from the cartilage of the first rib to the 

 coracoid process, constitutes the costo- 



coracoid membrane. In front of the sterno-mastoid muscle, the deep 

 fascia is attached to the border of the lower jaw and oshyoides, and forms 

 a distinct sheath for the submaxillary gland. Inferiorly it divides into two 

 layers, one of which passes in front of the sternum, while the other is at- 

 tached to its superior border. 



FASCIA OF THE TRUNK. 



The thoracic fasda\ is a dense layer of cellule-fibrous membrane, 

 stretched horizontally across the superior opening of the thorax. It is 

 firmly attached to the concave margin of the first rib, and to the inner 

 surface of the sternum. In front it leaves an opening for the connexion 

 of the cervical with the thoracic portion of the thymus gland, and behind 

 it forms an arch across the vertebral column, to give passage to the 

 oesophagus. 



At the point where the great vessels and trachea pass through the tho- 

 racic fascia, it divides into an ascending and descending layer. The 



* A transverse section of the neck, showing the deep cervical fascia and its numerous 

 prolongations, forming sheaths for the different muscles. As the figure is symmetrical, 

 the figures of reference are placed only on one side. 1. The platysma myoides. 2. 

 The trapezius. 3. The ligamentum nuchse, from which the fascia may be traced br- 

 wards beneath the trapezius, enclosing the other muscles of the neck. 4. The point at 

 which the fascia divides, to form a sheath for the sterno-mastoid muscle (5). 6. The 

 point of reunion of the two layers of the sterno-mastoid sheath. 7. The point of union 

 of the deep cervical fascia of opposite sides of the neck. 8. Section of the sterno-hyoid. 

 9. Omo-hyoid. 10. Sterno-thyroid. 11. The lateral lobe of the thyroid gland. 12. The 

 trachea. 13. The oesophagus. 14. The sheath containing the common carotid artery, 

 internal jugular vein, and pneumogastrie nerve. 15. The 'longus colli. The nerve in 

 front of the sheath of this muscle is the sympathetic. 16. The rectus anticus major. 

 17. Scalenus anticus. 18. Scalenus posticus. 19. The splenius capitis. 20. Splenius 

 colli. 21. Leva tor anguli scapulae. 22. Complexus. 23. Trachelo-mastoid. 24. Trans- 

 versalis colli. 25. Cervicalis ascendens. 26. The semi-spinalis colli. 27. The multi- 

 fid us spinoe. 28. A cervical vertebra. The transverse processes are seen to be traversed 

 by the vertebral artery and vein. 



-j- For an excellent description of this fascia, see Sir Astley Cooper's worlc "n ^' 

 u Anatomy of the Thymus Gland." 



23 



