Human Anatomy Vol 1

Boundories

Anteriorly: Infrasternal angle between the two costal
margins.

Posteriorly: Lrferior surface of the body of the twelfth
thoracic vertebra.

On each side: Costalmargin formed by the cartilages of
seventh to twelfth ribs.

INTRODUCTION

Diophrogm of the Outlet of Thorox

The outlet is closed by a large musculotendinous

partition, called the diaphragm-the thoracoabdominnl

diaphragm-which separates the thorax from the

abdomen.

There are three large and several small openings in the

diaphragm which allow passage to structures from

thorax to abdomen or uice uersn (Fig.12.76).

Large openings; These are vena caval opening in the

central tendon, oesphageal opening in the right crus of

diaphragm and aortic opening behind the median

arcuate ligament.

The structures passing through large openings are

put in Table 12.1.

Small open.ings: Superior epigastric artery passes in

space of Larrey present between slip of xiphoid Process

and 7th costal cartilaginous slip of the diaphragm.

When foramen is enlarged it is known as foramen of

Morgagni.

Musculophrenic artery perforates diaphragm at the

level of 9th costal cartilage.

Lower 5 intercostal vessels and nerves pass between

costal origins of diaphragm and transversus abdominis.

Subcostal vessels and nerves pass behind lateral

arcuate ligament. Sympathetic trunk passes behind

medial arcuate ligament. Greater and lesser splanchnic

nerves pierce each crus. Left phrenic nerve pierces left

cupola.

Thoracic cavity houses a single heart with

pericardium, two lungs with pleurae, blood

vessels, nerves and lymphatics.

Rib may be present in relation to cervical seven

and lumbar one vertebrae. The cervical rib may

give symptoms.

Ribs are weak at their angles and are vulnerable

to injury at that area.

. Apex beat lies below and to the normally
placed left nipple.
2nd costal cartilage at the manubriosternal angle
is extremely important landmark. The 2nd
intercostal space lies below this cartilage and is
used for counting the intercostal spaces for the
position of heart, lungs and liver.
7-7 ribs with costal cartilages reach the sternum,
costal cartilages of 8-10 ribs form the costal margin,
while 11th and 12th ribs do not reach the front at
all.

Affected hand

Fig. 12.14: Wasting of small muscles of hand

Tortuous

intercostal

artery

Fig. 12.15: Tortuous intercostal artery receives blood from

anterior intercostal artery, transfers it to descending aorta

beyond cdarctation. Tortuous intercostal artery produces

notches in the rib