CUTANEOUS NERVES OF CHEST. 13 



costal space. And the rest (lateral cutaneous of the thorax) should 

 be looked for along the side of the chest, about an inch behind the 

 anterior fold of the axilla, there being one from each intercostal and inter- 

 space except the first. As these last-mentioned nerves pierce the jjjjj* ; 

 wall of the thorax, they divide into anterior and posterior branches. 

 The posterior branches of the highest two of them are larger than 

 the rest, and are to be followed across the armpit, where a junction 



will be found with a branch (nerve of Wrisberg) of the brachial nerve of 



Wrisberg. 



plexus. 



CUTANEOUS NERVES FROM THE CERVICAL PLEXUS. These cross Cutaneous 



the clavicle and are distributed to the skin over the pectoral muscle. 

 The most internal branch (sternal) lies near the inner end of the plexus. 

 bone, and reaches but a short distance below it. Other branches 

 (clavicular), two or more in number and larger, cross the middle 

 of the clavicle, and extend to near the lower border of the pectoralis 

 major ; they join one or more of the anterior cutaneous nerves. 



The CUTANEOUS NERVES OF THE THORAX are derived from the Cutaneous 

 trunks of the intercostal nerves between the ribs. Of these there JStercostais. 

 are two sets : One set, the lateral cutaneous nerves,. arise about 

 midway between the spinal column and the sternum. The other 



t, the anterior cutaneous nerves, are the terminations of the same 

 trunks at the anterior ends of the intercostal spaces. 



The ANTERIOR CUTANEOUS NERVES are slender filaments which One near 

 pierce the pectoral muscle, and are directed outwards to supply the 

 skin and the mammary gland. The offset of the second nerve joins 

 a cutaneous branch from the cervical plexus. Small branches of 

 the internal mammary vessels accompany these nerves. 



The LATERAL CUTANEOUS NERVES (fig. 4, p. 15) issue with com- The other 



on side of 



panion vessels between the digitations of the serratus magnus the chest ; 

 muscle, and divide into anterior and posterior branches. There is 

 not usually any lateral cutaneous nerve from the first intercostal 

 trunk. 



The anterior offsets (fig. 4 9 , p. 15) bend over the pectoral muscle, these have 

 and end in the integuments and the mammary gland ; they increase antenor and 

 in size downwards, and the lowest give twigs to the digitations of 

 the external oblique muscle. The cutaneous nerve of the second 

 intercostal trunk commonly wants the anterior offset. 



The posterior offsets (fig. 4 8 , p. 15) end in the integuments over posterior 

 the latissimus dorsi muscle and the back of the scapula, and decrease bl 

 in size from above downwards. 



The lateral branch of the second intercostal nerve (fig. 4 ?, p. 15) One reaches 

 is larger than the rest, and is named the intercosto-humeral. Per- 

 forating the fascia of the axilla, it is distributed to the skin of the 

 arm (p. 43). As it crosses the axilla it is divided into two or more 

 pieces, and is connected to the nerve of Wrisberg, or lesser internal 

 cutaneous, by a filament of variable size. 



The branch of the third intercostal nerve gives filaments likewise Third nerve. 

 to the armpit and the inner side of the arm. 



The MAMMA is the gland for the secretion of the milk, and is The breast: 

 situate on the lateral part of the front of the chest. 



