214 LABORATORY MANUAL OF HUMAN ANATOMY 



border of the inferior belly (venter inferior) of the M. omo- 

 hyoideus. Beneath the tendinous part of the M. omohyoideus, 

 where it passes below the sternomastoid, secure the small nerve- 

 twig from the descending ramus of the hypoglossal nerve (R. de- 

 scendens N. hypoglossi) which goes to it. How is the posterior 

 triangle bounded in front, behind, and below? How is its apex 

 formed? The inferior belly of the omohyoid muscle divides it 

 into (a) an upper, larger part, the occipital triangle, and (6) a 

 lower, very much smaller part, the supraclavicular triangle. 

 Notice the chain of lymph-glands at the posterior border of the 

 M. sternocleidomastoideus. They are often inflamed in diseases 

 of the scalp (impetigo pedicularis) . 



The Occipital Triangle. 



What are its boundaries f How is its floor formed from above 

 downward? Observe among its contents the following : 



Arteries. (Vide Fig. 97, p. 236.) 



(a) Occipital artery (A. occipitalis) occasionally. 



(b) Transverse artery of neck (A. transversa colli}. 

 Veins. 



(a) Occipital vein (V. occipitalis}. 



(b) Transverse vein of neck (V. transversa colli). 

 Nerves. 



(a) Supraclavicular branches of the cervical plexus (Nn. supraclavicu- 



lar -es). 



(b) Accessory nerve (N. accessorius) (0. T. spinal accessory). 



(c) Branches of cervical nerves to M. trapezius and to M. levator scap- 



ulae (rami muscular es Nn. cervicalium) . 



Many of these structures will be studied more particularly 

 when the body is turned on its face and the back of the neck is 

 dissected. 



The Supraclavicular Triangle (O. T. Subclavian Triangle). 



The fascia praevertebralis may be removed where it covers 

 the vessels and nerves. Note its continuity with the axillary 

 sheath. What are the boundaries of the supraclavicular tri- 

 angle! Find and study the following structures, and compare 

 each as found in the cadaver with the description in your text- 

 book of systematic anatomy. 



Arteries. (Vide Fig. 16, p. 63.) 



(a) Third portion of subclavian artery (A. subclavia). 



(b) Transverse artery of neck (A. transversa colli). 



(c) Transverse artery of scapula ( A. transversa scapulae) (0. T. supra- 



scapular). 



