THE UPPER LIMB ' 31^ 



with one of the muscular branches, and it takes a backward course 

 behind the in tercos to-humeral nerve to be distributed to the 

 integument of the back of the arm, reaching nearly as low as the 

 elbow. 



Intercosto-humeral Nerve. — The intercosto-humeral nerv^e is the 

 undivided lateral cutaneous branch of the second intercostal, and 

 it represents the posterior branch of the other lateral cutaneous 

 ner\'es. Emerging from the second intercostal space it appears 

 between two serrations of the serratus magnus, and then crosses 

 the axillary space. In its course it usually Conununicates with a 

 branch of the posterior division of the lateral cutaneous of the third 

 intercostal, and towards the arm it also communicates with the 

 nerve of Wrisberg and the internal cutaneous of the musculo-spiral. 

 On reaching the arm it is distributed to the integument of the 

 inner and back part over the upper half. Sometimes there is 

 another intercosto-humeral nerve, which is the undivided lateral 

 cutaneous branch of the first intercostal nerve. When this is so 

 the nerve of Wrisberg is absent. 



The lateral cutaneous nerves have been previously described in 

 connection with the cutaneous nerves of the pectoral region on 

 page 279. It may be stated, in addition, that the posterior branch 

 of the lateral cutaneous of the third intercostal, as a rule, gives 

 a branch across the axiUa to the inner side of the arm, which 

 communicates in its course with the intercosto-humeral, and may 

 largely replace it, if it is small. 



Axillary Lymphatic Glands. — ^The axillary glands are very numer- 

 ous, and He embedded in the loose adipose tissue of the axillary 

 space. They are disposed in four groups — external, or humeral ; 

 antero-intemal, or pectoral ; posterior, or subscapular ; and central. 



The external or humeral glands are about six in number, and lie 

 upon the outer wall of the space, where they form a chain along 

 the axiUary vein. Their afferent vessels represent (i) most of the 

 superficial cind deep lymphatics of the upper limb, (2) some of the 

 efferent vessels of the pectoral axillary glands, and (3) some of the 

 efferent vessels of the subscapular glands. Their efferent vessels 

 pass to (i) the central axillary glands, (2) the infraclavicular glands, 

 and (3) the* supraclavicular glands. 



The antero-intemal or pectoral glands are about six in number^ 

 and are situated along the inferior or long thoracic artery at the 

 lower border of the pectoralis minor muscle, and therefore within 

 the anterior fold of the axilla. They lie upon the serratus magnus, 

 in the angle between it and the pectoral muscles, and they extend 

 from the level of the second to the level of the fifth intercostal 

 space. They receive their afferent vessels from (i) the anterior and 

 lateral parts of the thoracic waU, and the supra-umbilical portion 

 of the abdominal wall, and (2) the outer two-thirds of the mammary 

 gland. Their efferent vessels pass to (i) the external axillary glands, 

 (2) the central axillary glands, and (3) the infra-clavicular glands. 



The posterior or subscapular glands are about five in number, and 

 are situated upon the posterior wall of the axilla. They lie along 



