Download 4_Diaphragm

Objectives
 Discuss the origin and insertion of diaphragm.
 Enlist the openings (with their contents) in the
diaphragm.
 Give the motor and sensory nerve supply of
the diaphragm.
Diaphragm
 The diaphragm is a thin
musculo-tendinous septum
that separates thorax &
abdominal cavities.
 It is pierced by the structures
that pass between the chest
and the abdomen.
 The diaphragm is the most
important muscle of
respiration.
 It is dome shaped and consists
of a peripheral muscular
part, which arises from the
margins of the thoracic
opening, and a centrally
placed tendon.
Origin of diaphragm
The origin of the diaphragm
can be divided into three
parts:
1- Sternal origin:
Back of xiphoid process of
sternum.
2- Costal origin:
Inner aspect of lower 6 ribs &
C.Cs. Forms the rt & lt domes
3- Vertebral origin:
Two crura:
• Right crus arises from the
ventral aspect of the upper
three lumbar vertebrae.
• Left crus arises from the
upper two lumbar vertebrae.
Origin of diaphragm
Origin of diaphragm
b. Arcuate ligaments:
* Median arcuate ligament:
A median tendinous arch
connecting the right and
left crura.
* Medial arcuate ligament:
On each side, connecting
each crus with the tip of
transverse process of L1.
* Lateral arcuate ligament:
On each side, connecting
the tip of transverse
process of L1 with the last
rib.
Origin
of
diaphragm
Insertion of diaphragm
Into the central tendon of
diaphragm which is
formed of three lobes:
1- Right lobe.
2- Left lobe.
3- Median lobe.
* The central tendon is
depressed and the
lateral parts are
elevated forming the
right and left copula =
dome.
Insertion of Diaphragm- Central Tendon
 The diaphragm is inserted into a
central tendon.
 The superior surface of the tendon
is partially fused with the inferior
surface of the fibrous
pericardium.
 Some of the muscle fibers of the
right crus pass up to the left and
surround the esophageal orifice in
a slinglike loop.
 These fibers appear to act as a
sphincter and possibly assist in
the prevention of regurgitation of
the stomach contents into the
thoracic part of the esophagus.
Insertion of Diaphragm-Central Tendon
Nerve Supply of the Diaphragm
 Motor nerve supply:
 The right and left phrenic
nerves (C3, 4, 5)
 Sensory nerve supply:
 The parietal pleura and
peritoneum covering the
central surfaces of the
diaphragm are supplied by the
phrenic nerve
 The periphery of the
diaphragm is supplied by the
lower six intercostal nerves.
Nerve
supply of
diaphragm
Actions of the diaphragm
Action:
1- Muscle of inspiration:
On contraction the diaphragm pulls its central tendon
down and increases the vertical diameter of the thorax.
The diaphragm is the most important muscle used in
inspiration
2- Increase the intra abdominal pressure in forced
actions:
Assists the contraction of the muscles of the anterior
abdominal wall in raising the intra-abdominal pressure
for micturition, defecation, and parturition
3- Right crus acts as a sphincter to the lower end of
esophagus.
4- Thoracoaabdominal pump:
 The descent of the diaphragm decreases the intrathoracic
pressure & increases the intra-abdominal pressure.
 This compresses the blood in the inferior vena cava and
forces it upward into the right atrium of the heart.
 Within the abdominal lymph vessels is also
compressed, and its passage upward within the thoracic
duct is aided by the negative intrathoracic pressure.
 The presence of valves within the thoracic duct prevents
backflow.
Actions of diaphragm
Major openings in the diaphragm
Major openings in the diaphragm
1- IVC opening:
a.Site: In the central
tendon of diaphragm
between right and
median lobe.
b.Level: T8
c.Structures passing
through:
1)Inferior vena cava.
2)Right phrenic nerve.
3)Lymphatics.
Major openings in the diaphragm
2- Aortic opening:
a.Site: Posterior to
median arcuate
ligament.
b.Level: T12
c.Structures passing
through:
1)Aorta.
2)Azygos vein.
3)Thoracic duct.
Major openings in the diaphragm
3- Oesophageal
opening:
a.Site:Right crus.
b.Level: T10
c.Structures passing
through:
1)Oesophagus.
2)Vagi.
3)Anastomotic branches
between left gastric
and aortic
oesophageal
arteries.
Other structures passing through diaphragm
1-Splanchnic nerves
which pierce the crura.
2-Inferior hemiazygos
vein which pierce the
left crus.
3- Psoas major M.
4-Sympathetic trunk
(pass deep to the medial
arcuate ligament).
5-Quadratus
lumborum.
6- Subcostal N, Vs
(Pass deep to the lateral
arcuate ligament).
Other structures passing through the
diaphragm
7-Lower five intercostal Nerves and vessels.
8-Superior epigastric vessels.
9-Musculophrenic vessels.
10- Lt phrenic nerve
Blood
supply
 The phrenic
artery.
 The
musculophrenic
.
 Branches of the
mammary
artery.
 The intercostals.
Clinical notes
 Hiccup
 Hiccup is the involuntary spasmodic contraction of the diaphragm accompanied by
the approximation of the vocal folds and closure of the glottis of the larynx. It is a
common condition in normal individuals and occurs after eating or drinking as a
result of gastric irritation of the vagus nerve endings. It may, however, be a
symptom of disease such as pleurisy, peritonitis, pericarditis, or uremia.
 Paralysis of the Diaphragm
 A single dome of the diaphragm may be paralyzed by crushing or sectioning of the
phrenic nerve in the neck. Occasionally, the contribution from the fifth cervical
spinal nerve joins the phrenic nerve late as a branch from the nerve to the
subclavius muscle. This is known as the accessory phrenic nerve. To obtain
complete paralysis under these circumstances, the nerve to the subclavius muscle
must also be sectioned.
 Penetrating Injuries of the Diaphragm
 Any penetrating wound to the chest below the level of the nipples should be
suspected of causing damage to the diaphragm until proved otherwise. The arching
domes of the diaphragm can reach the level of the fifth rib (the right dome can
reach a higher level).
Thank You
Prof.: Dr. Wafaa Abdel-Rahman
Dr. Rania Gabr