Thoracic wall and Diaphragm

Question 1

Diaphragm anatomy

Answer 1

Musculotendinous partition between thorax and abdomen
A major muscle contributor to respiration- 75% of change in thoracic volume
Components- tendinous dome in center, two crura

Question 2

Openings in diaphram

Answer 2

Three- hiatus, foramen
Aorta- communicates with retroperitoneal space
Esophagus
Caudal vena cava- on right side

Question 3

Radiographic anatomy

Answer 3

Diaphragm often appears different in R vs L lateral views
The most dependent (down) crus is usually more cranial
Helps identify whether image is a L or R lateral view based on diaphragm appearance- not reliable in cats (not in big dogs)

Question 4

Radiographic anatomy- Right lateral

Answer 4

Left to right
R crus more cranial
CVC attaches to R crus
Therefore CVC silhouettes with most cranial crus
R and L crus are more parallel

Question 5

Radiographic anatomy- left lateral

Answer 5

Right to left
L crus more cranial
CVC superimposed on most cranial crus and silhouettes with mroe caudal crus
R and L crus more divergent
Fundus on stomach caudal to L crus

Question 6

Radiographic anatomy- DV/VD

Answer 6

Appearance less predictable than lateral
In VD you may detect 1, 2, or 3 dome shaped stuctures
In DV usually only one

Question 7

Acquired diaphragmatic hernias

Answer 7

abdominal viscera protrudes through diaphragm- into pleural space
most common cause = trauma
may or may not result in clinical signs- may have concurrent pleural fluid
many are difficult to diagnose
May need additional tests- US, barium study
if pleural fluid present, thoracocentesis and repeat radiography is therapeutic and diagnostic

Question 8

Traumatic diaphragmatic hernia

Answer 8

Helpful radiographic signs: border effacement (silhouetting) of diaphragm
Abdominal viscera in pleural space
abnormal location of abdominal structures

Question 9

Peritoneaopericardial diaphragmatic hernia

Answer 9

Abdominal viscera herniates into pericardial sac through congenital defect between ventral thorax and abdomen- ventral aspect of diaphragm is incomplete and allows a passageway- also defect in pericardial sax so it ends up there
Sometimes associated with fewer than normal sternebra
Usually an incidental finding
occasionally produces clinical signs
Round, enlarged cardiac silhouette- hard to tell from pericardial effusion and generalized cardiomegaly
Cardiac silhouette has heterogeneous opacity if gas or large amount of fat present

Question 10

Hiatal hernia

Answer 10

Portion of fundus herniated through esophageal hiatus

Two type: sliding (more common in animals), paraesophageal

Question 11

Sliding hiatal hernia

Answer 11

Fundus slides back and forth between thorax and abdomen

Question 12

Thoracic wall

Answer 12

Ribs often ignored- many rib lesions missed, critical part of thoracic assessment
Fake outs from superficial nodules common

Question 13

Costal cartilages

Answer 13

Commonly mineralize- even in young dogs (makes them more opaque)
Once mineralized (stiff) exuberant calcifications can form around the costochondral junction- commonly confused with tumors, infection or lung nodules

Question 14

Skin nodules

Answer 14

Can appear as lung nodules
Nodules are very distinct
may need additional views
Can apply contract medium to area and retake radiograph

Question 15

Rib Fractures

Answer 15

Rarely clinically significant
Can be spontaneous in cats
Healing pattern same as long bone

Question 16

Thoracic wall masses

Answer 16

Sometimes hard to tell thoracic wall mass from lung mass
Thoracic one will have rounded corner
intrapulmonary= sharp corner