PARACENTESIS THORACIS 347 



through an intercostal space and the needle is inserted across 

 the upper border of the rib which bounds the space inferiorly 

 in order to avoid the intercostal vessels and nerve, since they 

 lie in relation to the lower border of the rib bounding the 

 space superiorly. 



The precise site of the puncture depends on the individual 

 case, but care must be taken not to insert the needle too near 

 to the upper or to the lower border of the dull area. In the 

 former case, the lung is penetrated, and, in the latter case, the 

 diaphragm may be pierced. When possible, the needle may 

 be passed in through the fifth intercostal space in the 

 mid-axillary line. In well-developed subjects it may be 

 difficult to identify the fifth space in that situation, but it can 

 be identified by drawing a line horizontally round the body at 

 the level of the fourth chondro-sternal articulation. This line 

 intersects the mid-axillary line on the fifth rib or fifth 

 intercostal space. 



The seventh space in the scapular line is a favourite site for 

 puncture and also for the operation of Paracentesis thoracis. 

 When the arm is by the side, the space is covered by the 

 inferior angle of the scapula, but, when the arm is abducted or 

 flexed beyond a right angle (p. 132), e.g., by placing the hand 

 on the top of the head, the space becomes uncovered. This 

 site possesses the advantage that, when the instrument is 

 withdrawn and the arm is replaced by the side, the track of the 

 needle or cannula becomes obliterated to a large extent. 



The NERVE-SUPPLY to the costal pleura is derived from 

 the intercostal nerves ; the diaphragmatic pleura receives 

 branches from the phrenic nerve; the pulmonary pleura 

 is supplied by the terminal branches of the pulmonary 

 plexuses (p. TOO). The pain of pleuritic inflammation may be 

 referred to the peripheral sensory distribution of those nerves 

 which have their centres in the spinal medulla at the same 

 level as the nerves of supply to the pleura (p. 191). Abdominal 

 pain and rigidity of the abdominal muscles are often associated 

 with empyaema and with the pleurisy which accompanies the 



