138 



APPLIED ANATOMY. 



from about the junction of the outer and middle thirds of the clavicle to a variable 

 distance, up to 2.5 cm. (i in.), above the clavicle at the anterior edge of the sterno- 

 mastoid muscle. The omoyhoid muscle has its lower attachment at the posterior 

 edge of the suprascapular notch, which is below the level of the clavicle, and its 

 posterior belly is sometimes concealed behind the clavicle and does not rise above it 

 except at its inner extremity beneath the sternomastoid muscle. It is rare that any 

 distinct triangle is formed, hence as far as the surface markings are concerned 

 there is often no subclavian triangle. Therefore the posterior cervical triangle will 

 be considered as a whole and not divided. 



It is covered by the skin, beneath which is the subcutaneous tissue, which at its 

 lower portion contains the fibres of the platysma muscle. Its floor is composed 

 from above downward of the splenius, levator scapulcz, scalenus posticus, scalenus 

 medius, and scalenus anticus muscles. The deep fascia of the neck spans the 

 space and splits anteriorly to enclose the sternomastoid muscle and posteriorly to 



~Occipitalis major nerve 

 Occipital artery 

 'ccipitalis minor nerve 



Splenius muscle 



Auricularis magnus nerve 



Superficial cervical nerve 



Levator scapulae muscle 



Spinal accessory nerve 



Trapezius 



Middle scalene muscle 



Posterior scalene muscle 

 External jugular vein 



Omohyoid muscle 



Sternomastoid muscle 

 Anterior scalene muscle 

 Phrenic nerve 

 Internal jugular vein 

 Omohyoid muscle 



Transverse cervical 

 artery 

 Brachial plexus 



Suprascapular artery 



Subclavian vein 



Subclavian artery 



FIG. 169. Dissection of the posterior cervical triangle. 



enclose the trapezius. The space contains important arteries, veins, nerves, and 

 lymphatics. 



External Jugular Vein. Lying on the deep fascia and beneath the super- 

 ficial fascia and platysma is the external jugular vein. This begins below the ear 

 and posterior to the ramus of the jaw, being formed by the union of the temporo- 

 maxillary and posterior auricular veins. It passes downward and slightly backward 

 on the surface of the sternomastoid muscle to its posterior border, which it reaches at 

 about the middle and follows down until about a centimetre above the clavicle; here 

 it pierces the deep fascia and dips behind the clavicular origin of the sternomastoid 

 muscle to empty into the subclavian. It has one pair of valves about 4 cm. above 

 the clavicle, and another pair at its point of entrance into the subclavian. They do 

 not entirely prevent a regurgitation of the blood. 



The external jugular vein receives the posterior external jugular vein, and the 

 suprascapular and transverse cervical veins. The occipital may also enter into it. 

 The veins of the neck are exceedingly irregular in their formation and may vary 

 considerably. The external jugular' is readily seen through the skin, it may be 

 made more prominent by compressing it just above clavicle. In operations in this 



