Download THORACIC INLET RELATIONS AND CROSS SECTIONAL ANATOMY

THORACIC INLET RELATIONS AND CROSS
SECTIONAL ANATOMY
Learning Objectives
At the end of this class the student will be able to,
•Under stand the location of the thoracic inlet.
•Under stand the boundaries of thoracic inlet.
•Under stand the important relations of different
structures at this level
THORACIC INLET
•Thoracic inlet is reniform.
•About 5 cm anterioposteriorly.
•About 10 cm transversely.
•Plane of inlet slops downwards and
inwards.
BOUNDARIES
•Behind is the first thoracic
vertebrae.
•In front is superior border of
manubrium sternae.
•On each side is first rib.
•In female thoracic inlet is more oblique than in man.
Structure traversing the
superior thoracic aperture:
•Form two groups.
•1.Those in or near the median
plane.
•2.Those on each side (closely
related to the cervical parts of
pleurae and lungs).
Suprapleural membrane
• Thickening of endothoracic fascia
• Tent shaped fibrous sheet
• covers lateral part of inlet
Attachment
• Laterally
– medial border of first
rib and costal
cartilage
• at its apex
– transverse process
of 7th cervical
vertebrae
• Medially
– fascia investing the structures passing through
inlet
Function
• Protects underlying cerviacal pleura
• Resist changes in intrathoracic pressure
•NEAR THE MIDLINE.
•1.Behind
the manubrium:
•The
lowest parts of the
sternothyroid muscles enter
the thorax.
•Behind
are the sternothyoid
muscles, thymic vestiges
and inferior thyroid veins
passing down to
brachiocephalic veins.
2.In children.
•Particularly the left brachiocephalic veins it self may be
in the thoracic inlet.
3.Posteriorly.
•Trachea and oesophagus with the recurrent laryngeal
nerves (which occupy the median region).
4.Behind the left oesophageal margin.
•Thoracic duct enters the neck.
5.Anterior to the vertebral column.
•The longus colli muscles and anterior longitudinal
ligament.
ON EACH SIDE.
1.The upper part of the pleura and pulmonary apex
occupy the inlet.
2.Between the pleura and neck of first rib
(mediolaterally), are the sympathetic trunk. Superior
intercostal artery and ventral ramus of first thoracic
nerve passing (superolaterally) to the brachial plexus.
3.Anteriorly. Between pleura and first costal cartilage,
the internal thoracic artery enters the thorax, medial to
the artery its vein leaves the thorax.
ON THE RIGHT.
•The brachiocephalic artery leaves the thorax between
the trachea and pleura.
•The vagus nerve, having passed between subclavian
artery and veins, is between pleura and the
brachiocephalic artery at the inlet.
•The right brachiocephalic artery at the inlet.
•Right brachiocephalic vein enters the thorax
anterolateral to its artery.
•The right phrenic nerve crosses the internal thoracic
artery and its lateral to the first costal cartilage.
ON THE LEFT.
•The
left common
carotid and
subclavian arteries
leaves the thorax
between the pleura and
trachea, the left vagus
nerve descending
lateral to the interval
between them.
•Anterolateral
•The
to this is the left brachiocephalic vein.
left phrenic nerve crosses the internal thoracic
artery at a higher level than on the right hand and, at the
inlet, it is between the left brachiocephalic vein
anterolaterally and subclavian and common carotid
arteries posteromedially.
STRUCTURES RELATED TO RIGHT CERVICAL PLEURA
FROM BELOW
STRUCTURES RELATED TO RIGHT CERVICAL PLEURA
FROM BELOW
CROSS SECTION AT T2 LEVEL
THANKS