Perlatividad

In the inguinal region three conduits are exposed, namely the inguinal space (canal), the lacuna neuromusculorum and the lacuna vasorum. Initially, the right inguinal mamma is reflected medially, and following this, one is able to study the participation of the five layers of the abdominal wall in the forma- tion of the inguinal space. This begins at the internal or deep inguinal ring and ends at the external or superficial inguinal ring. Observe the continuation of the external fascia of the trunk as the tubelike external spermatic fascia. Externally, this envelops the vaginal process and its covering of internal spermatic fascia. Then on the right side, the external trunk fascia, the three expansive abdominal muscles, the transversalis fascia and the peritoneum are transect- ed and reflected. This incision is made along the long axis of the external inguinal ring as far as the costal arch. In so doing, each individual abdominal lay- er is studied.

b) The NEUROMUSCULAR LACUNA (see also text-illustration) is passage for

the m. iliopsoas and the femoral n. contained within it. At the level of the lacuna and the transition from lateral to dorsal body wall, the transversalis

PARTICIPATION OF LAYERS OF THE ABDOMINALWALL IN FORMING THE INGUINAL SPACE (INGUINALCANAL) ANDRECTUS SHEATH

Abdomen Ring Process Rectus Sheath

I. Skin ––– Skin of scrotum –––

II. External trunk fascia ––– Ext. spermatic fascia Ext. lamina III. M. obl. ext. abdom. Ext. inguinal ring Ext. lamina

III. M. obl. int. abdom. Int. inguinal ring Ing. space (canal) Ext. lam.; ext. and int. lam.; int. — — — — — — — — — — — — — — — — — — M. cremaster (ext.) –––

III M. transv. abdom. ––– Ext. lam.; ext. and int. lam.; int. IV. Internal trunk fascia ––– Int. spermatic fascia Lam. int.

V. Peritoneum Vaginal ring Vaginal process (female) ––– Vaginal tunic (male)

18 4 14 1 2 7 3 26 17 16 15 10

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26 19 8 9 18 27 10 28 29 30 15 17 22 5 _{31 32} 23 25 24 21 16 17 24 22 20 26 33 34 28 29 ₃₀ 2 3 4

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Inguinal region

Legend : ( caudoventral view) (see p. 35) 4 Iliopsoas m. 3 Inguinal ligament

2 Ext. iliac fascia (Iliac lamina) 1 Int. iliac fascia

Iliac fascia: (femoral canal) 13 Femoral space 12 Femoral trigone 11 Saphenous n. 10 Femoral n. 9 Vaginal ring 8 Peritoneum 7 Int. transversalis fascia of trunk 6 Transversus abdom. m. 5 Ext. (deep)fascia

of trunk

peritoneum 24 Vaginal process of 23 Spermatic fascia 22 Cremaster m. (ext.) 21 Ext. spermatic fascia

and genitofemoral n. 20 Ext. pudendal a. and v. 19 Rectus abdominis m. 18 Int. inguinal ring (deep) 17 Ext. inguinal ring (supf.) 16 Lateral crus

15 Medial crus

Ext. abdom. oblique m. 14 Int. abdom. oblique m.

25 Skin of scrotum 26 Linea alba 27 Ext. iliac a. and v.

28 Lacuna musculorum 29 Lacuna vasorum 30 Femoral ring Iliopsoas m.: 31 Iliacus m. 32 Psoas minor m.

33 Testicular a. and v. and Deferent duct 34 Supf. inguinal ln.

( )

38

In the lung field, the triangular field that projects the lung onto the lateral thoracic wall of its respective side, this main respiratory organ is external- ly accessible for auscultation and percussion. In a dog in the normal stand- ing attitude, the cranial border of the triangle is at the level of the 5th _rib.

With the thoracic limb drawn forward, the lung field can be increased about the width of two ribs. The dorsal border of the triangle is the later- al border of the iliocostalis muscle, and the caudoventral (basal) border ascends from the costochondral junction of the sixth rib to the middle of the eighth rib to the vertebral end of the 11th _rib.

The external form of the lungs is inconstant as the lungs necessarily follow the varying dimensions of the thoracic cavity in the movements of respira - tion. Together, the two lungs resemble a cone (each lung forming a ‘half- cone’) with a cranially situated apex of the lung (Apex pulmonis) that pro - jects slightly beyond the thoracic inlet, and a large base (Basis pulmonis) that abuts the diaphragm.

The lung surface is covered by pulmonary (visceral) pleura (see p. 42). After embalming the cadaver, as a reflection of the plasticity of the lung parenchyma, the costal surface in situ shows distinct costal impressions. The medial surface (see text-illustration) extends dorsally with its vertebral

part up to the vertebral column; ventrally, in its mediastinal part, the fol-

lowing can be identified: the aortic impression (12), esophageal impression

(13) as well as the sulcus for the caudal vena cava (14), and continuing ven-

trally from the caval sulcus, the cardiac impression. The diaphragmatic sur-

face (16) lies smoothly upon the diaphragm.

a) The LUNGS (see text-illustration) of the dog are distinctly asymmetrical

because the right lung with its four lobes is considerably larger than the left lung with only two lobes.

Externally the pulmonary lobes in the dog are subdivided or set off by

interlobar fissures that are very deep and in part reach to the subdivision

of the bronchi.

I. The right lung (Pulmo dexter) is divided by cranial (2) and caudal (3) interlobar fissures into cranial (5), middle (4), and caudal (1) lobes, and the

small accessory lobe (see text-illustration, —17) that extends from the medial sur face into the mediastinal recess (see p. 42). The accessory lobe cannot be seen in lateral view. It partly passes over the caudal vena cava, forming the sulcus venae cavae caudalis. On the ventral border of the lung, the cranial interlobar fissure passes over into the right cardiac notch (6). The caudal interlobar fissure separates the middle lobe from the caudal lobe, which, medially, is fused with the accessory lobe.

b) The BIFURCATION OF THE TRACHEA (see text-illustration, above —A) and

its division into the principal bronchi (B) determines the subdivision into right and left lung. The subdivision of the principal bronchi into lobar

bronchi, which cannot be discerned externally, is more significant in defin-

ing the lobes of the lung than the visible fissures, which are partly between the lobes, partly within a lobe.

The tracheal bifurcation is ventral to the esophagus, and is about halfway between the thoracic inlet and the diaphragm. For the ventilation of each lobe of the lung the principal bronchi divide into two lobar bronchi for the

left lung (cranial lobar bronchus —C and caudal lobar bronchus —D), and

in the right lung into four lobar bronchi (cranial lobar bronchus —E, mid-

dle —F, caudal —G and accessory —H).

The lobar bronchi give off segmental bronchi (I), which are designated according to their position as dorsal, ventral, lateral, and medial segmen- tal bronchi. The segments can be defined, for example, by anatomical cor- rosion casts. In the dog, the branches of the pulmonary artery accompany the segmental bronchus (bronchoarterial type of supply) in the caudal lobe. They run in the center of the segments and the branches of the pulmonary veins mark the periphery of the segments. In the cranial and middle lobes the segmental bronchi are not only accompanied by arterial branches but also by venous ones (bronchovascular type of supply). Because the pul- monary segment is ventilated by only one segmental bronchus, in case of bronchial occlusion, on a radiograph the segment is visible as a wedge-like shadow with a central wedge-shaped tip and a peripheral base. There, where the bronchial cartilages disappear, the smaller branches of the seg- mental bronchi continue as bronchioles, which are smaller than 1 mm in diameter. The terminal parts of the air conducting system, the terminal bronchioles, continue as the gas-exchange system, to which belong the res- piratory bronchioles (diameter smaller than 0.5 mm), the alveolar ducts and alveolar sacs, and finally the alveolus.

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In document Diccionario Teórico-práctico De Preposiciones Espaciales: (página 77-0)