360 AXILLA. 



surface, longer on the anterior, and longer still being, according to his views, to associate the 

 at the lower edge. The surface now exposed muscle to which it is distributed with the ge- 

 was covered by cellular tissue, and concealed neral respiratory movements. It was known to 

 by the pectoralis major every where except a antecedent anatomists as the posterior thoracic 

 small part of its lowest digitation, which is branch of the brachial plexus.* 

 generally to be seen below it, in contact with Crossing the axilla from the thorax to the 

 the integuments. arm, we see two nerves, frequently called nerves 

 The upper edge of this muscle is nearly hori- of Writberg, They are the external branches, 

 zontal, and placed about an inch below the or cozto-humcral, of the second and third inter- 

 clavicle. In the space between, when some costal nerves. They pierce the external layer 

 fat is carefully removed, and some absorbent of intercostal muscles opposite the origin of the 

 glands, we see the axillary artery running down- serratus magnus, between the second and third 

 wards and outwards, internal and anterior to and the third and fourth ribs, and pass out ob- 

 which is the axillary vein, and behind it the liquely to the arm, where they are lost in the in- 

 nerves. The cephalic vein is observed passing teguments on the inner and back part of the arm 

 upwards and inwards from the edge of the del- and elbow. The superior of them is the larger, 

 toid muscle to the axillary vein, and the tho- The great vessels and nerves are seen pass- 

 racica suprema artery standing forwards from ing from the first rib to the lower border of the 

 the axillary artery and resting on this edge of teres major muscle, forming an arch whose con- 

 the pectoral. The thoracica acromialis artery cavity is downwards. By raising the arm to 

 runs in this space out towards the acromion the horizontal position we obliterate the arch, 

 process, and is often a branch of the suprema. and by supinating the hand strongly we bring 

 Here, too, we see the lower surface of the sub- them more into view. In the upper third of 

 clavius muscle, turned forwards, and covered this curve the order of the parts, proceeding 

 by a pretty strong fascia which terminates in outwards, is, the axillary vein, axillary artery, 

 the costo-coracoid ligament. and plexus of nerves. In the middle the vein 

 The costo-coracoid ligament is very thin, but is situated as before, and then the nerves sur- 

 strong. It extends from the cartilage of the rounding and hiding the artery ; and in the 

 first rib, just below the origin of the subclavius inferior third we first meet the vein, then the 

 muscle, to the coracoid process of the scapula, nerves, and lastly the artery. 

 in an arch across the vessels and nerves. It is The axillary vein is about three inches in 

 concave inferiorly, and appears to be only the length, commencing a little above the edge of 

 thickened edge of the fascia which covers the the teres major ; thence it runs upwards, in- 

 subclavius and descends a little below that wards, and forwards to the second rib, which 

 muscle. This view of its true mode of forma- it touches, as also some fibres of the serratus 

 tion is favoured by the fact that it has an at- magnus there arising ; next it gets on the first 

 tachment also to the clavicle, and consequently intercostal muscles, after which it becomes the 

 may be called costo-cleido-coracoid. The name subclavian vein, crosses over the first rib, under 

 ligamentum bicorne is sometimes applied to in- the clavicle, before the scalenus anticus muscle, 

 dicate its horn-shaped extremities ; Blandin and then enters the thorax. It is formed by 

 denominates it fascia clavicularis, and Gerdy, the confluence of three veins, viz. the basilic 

 ligament suspenseur de I'aisselle. As a ligament and the two vena comites which convey their 

 it has little power, but as an aponeurosis it pro- fluid from the fore-arm, and it is afterwards en- 

 tects the vessels, and sends down a thin process larged by the accession of those veins which 

 upon them. accompany, usually in pairs, the subscapular, 

 Below the lesser pectoral the vessels and the thoracic, and the circumflex arteries. It 

 nerves again come into view, and the thoracica also receives the cephalic a little higher up, as 

 longior or external mammary artery is seen before described. 



passing downwards and forwards along its The axillary artery traverses this region 

 lower edge. For a fuller description of the pre- from above downwards in a course doubly ob- 

 ceding muscles, see THORAX, MUSCLES OF THE. lique, from within outwards, and from before 

 The inner wall of the axilla exhibits the ribs, backwards; at its upper part it rests on the 

 intercostal muscles, and serratus magnus, with chest separated by the serratus magnus muscle, 

 some vessels and nerves. One of these last is and lies close under the anterior wall of the 

 remarkable for its length and vertical direction ; axilla, whilst below it rests on the subscapularis 

 it lies on the serratus magnus, and appears as muscle (posterior wall), and is very near the 

 if flattened against the side of the thorax. It arm. Its complicated relations with the nerves, 

 arises generally by two branches from the back veins, glands, &c. come more properly under 

 of the anterior division of the fifth and sixth consideration in the next article (AXILLARY 

 cervical nerves (counting eight in the neck). It ARTERY), to which we refer, 

 communicates with the phrenic, descends be- 

 hind the brachial plexus, under the clavicle and ne r two f caSC of P^a ysis of the serratus 



magnus muscle from injury to this nerve have been 



trapezius, appears upon the serratus magnus, recorded. Velpeau mentions one, which resulted 



on which it runs a great distance and enters its from a blow inflicted on the inner wall of the axilla : 



lowest division by many filaments. It is classed a permanent projection of the posterior edge of 



among the respiratory nerves by Sir Charles Bell !. he sca P ula backwards, and inability to bring that 



by whom it has been named the inferior ex- ^l^^^^T^^^^'T^^ 



ft signs on which he founded his diagnosis. (See Cy- 



ternal respiratory nerve of the trunk, its function clop, of Pract. Mcd. art. PARALYLSIS.)-ED. 



