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THE THORACIC PLEXUSES. 653 
contributes also to the left anterior 
pulmonary plexus by fibres which 
extend outwards to the root of 
the lung along the left branch of 
the pulmonary artery. 
Pulmonary Plexuses.— As 
already stated, the pneumogastric 
nerve on each side, on reaching 
the back of the root of the lune, 
breaks up into numerous plexi- 
form branches for the formation 
of the posterior pulmonary plexus. 
From each nerve a tew fibres pass 
to the front of the root of the 
lung, above its upper border, to 
form the much smaller anterior 
pulmonary plexus. 
The anterior pulmonary 
plexus on each side is joined by 
a few fibres from the corresponding 
part of the deep cardiac plexus, 
and on the left side from the 
superficial cardiac plexus as well. 
It surrounds and = supphes the 
constituents of the root of the 
lung anteriorly. 
The posterior pulmonary 
plexus, placed behind the root of 
the lung, is formed by the greater 
part of the pneumogastric nerve, 
reinforced by fine branches from 
the second, third, and fourth 
thoracic. gangha of the sympa- 
thetic. Numerous branches pro- 
ceed from it in a plexiform manner 
along the bronchi and vessels into 
the substance of the lune. 
(sophageal Plexus (plexus 
gule).—The cesophagus in the 
thorax is supphed by the pneu- 
mogastric nerve both in the 
superior and = posterior media- 
stinum. Jn the superior media- 
stinum it receives branches from 
the pneumogastric nerve on the 
right side, and from its recurrent 
laryngeal branch on the left side. 
In the posterior mediastinum 
it is surrounded by the cesophageal 
plexus, formed from the trunks of 
the pneumogastric nerves emere- 
Fic. 469.—THE DISTRIBUTION OF THE PNEUMOGASTRIC NERVE. 
Va.R, Va.L, Right and left vagi; r, Ganglion of the root and 
connexions with Sy, Sympathetic, superior cervical gang- 
ing from the posterior pulmonary lion; G.Ph, Glosso- pharyngeal ; Acc, Spinal accessory 
plexus which torm a large plexus nerve ; m, Meningeal branch; Aur, Auricular branch ; t, 
Jb b > J J bo) J Dk b 
Ganglion of the trunk and connexions with Hy, Hypo- 
alossal nerve ; Cl, C2, Loop between the first two cervical 
nerves ; Sy, Sympathetic ; Acc, Spinal accessory nerve; Ph, Pharyngeal branch ; Ph.Pl, Pharyngeal plexus ; 
S.L, Superior laryngeal nerve; I.L, Internal laryngeal branch ; E.L, External laryngeal branch ; 1.0, 
Internal, and £.C, External carotid arteries ; Cal, Superior cervical cardiac branch ; Ca2, Inferior cervical 
eardiae branch ; R.L, Recurrent laryngeal nerve ; Ca3, Cardiac branches from recurrent laryngeal nerves ; 
Ca4, Thoracic cardiac branch (right vagus) ; A.P.P], Anterior, and P.P.P1, Posterior pulmonary plexuses ; 
Oes.Pl, Gsophageal plexus ; Gast.R, and Gast.L, Gastrie branches of vagus (right and left) ; Coe. Pl, 
Coeliac plexus ; Hep.Pl, Hepatic plexus ; Spl.Pl, Splenic plexus ; Ren.Pl, Renal plexus. 
