Diaphragm (Thoracoabdominal)

1. DIAPHRAGM
Dr. Prabhakar Yadav
Associate Professor
Department of Human Anatomy
B.P. Koirala Institute of Health

3. Diaphragm(Thoraco-abdominal):is a dome-
shaped muscle forming the partition between
thoracic & abdominal cavities.
• Principal muscle of respiration
Consists of: Peripheral- muscular part
Central fibrous part- central tendon
superior surface projects into thorax on either
side as dome
Depressed area between the two domes is -
central tendon
superior surface is covered by endothoracic
fascia
Superior surface is related to
---- bases of right & left pleura on sides
----- fibrous pericardium in the middle

5. Inferior surface of diaphragm is lined by the
diaphragmatic fascia & parietal peritoneum
On the right side it is related to:
(a) Right lobe of liver,(b) Right kidney
(c) Right suprarenal gland.
On the left side it is related to:
(a) Left lobe of liver, (b) Fundus of stomach, (c)
Spleen, (d) Left kidney (e) Left suprarenal gland.

6. Boundaries of thoracic outlet
(INFERIOR THORACIC APERTURE):
Anteriorly: Xiphisternal joint.
Posteriorly: Body of 12th thoracic vertebra.
Laterally (on each side): Costal margin and 11th
and 12th ribs.
Muscles arise from the circumference of
thoracic outlet & are inserted into a central
tendon.

7. Origin: Sternal part: Two fleshy slips, from posterior
surface of xiphoid process.
Costal part: six fleshy slips, from inner surface of lower
six ribs near their costal cartilages.
Vertebral part: Arises from(a) right & left crura of
diaphragm (b) Five arcuate ligaments
Crura
Left crus: vertical fleshy bundle, arises from anterior
aspects of upper two lumbar vertebrae & intervening
intervertebral discs of left side.
Right crus: vertical fleshy bundle, arises from anterior
aspects of upper 3 lumbar vertebrae & intervening
intervertebral discs of right side.
 Right crus is attached to more number of vertebrae
as right side diaphragm has to contract on liver.

8.  Medial margins of the crura are tendinous.
Arcuate ligaments
Median arcuate ligament: is an arched fibrous
band between upper ends of two crura.

9. Medial arcuate ligament: is a tendinous arch in the fascia covering the upper part of psoas major.
Extends from the side of the body of L2 vertebra to the tip of transverse process of L1 vertebra.
Lateral arcuate ligament :is a tendinous arch in the fascia covering upper part of quadratus lumborum.
Extends from tip of transverse process of L1 vertebra to the 12th rib.

10. Insertion: Muscle fibres converge towards
central tendon & insert into its margins.
Central tendon is trilobar in shape, having an
anterior (central) leaflet, & two tongue-
shaped right and left leaflets.
• Superior surface of central tendon of the
diaphragm lies below the pericardium
and is fused to it.

11. Openings of Diaphragm
Aortic opening: lies at the level of T12 in the
midline behind median arcuate Ligament
(anterior to body of T12 vertebra between the
crura).
Transmits: Aorta, Thoracic duct, Azygos vein.
(Contraction of diaphragm has no effect on the
aortic opening because strictly it is outside the
diaphragm.)
Esophageal opening: lies at the level of T10 in
a sling of muscle fibers derived from the right
crus.
Transmits: Esophagus, Right and Left vagus
nerves, Esophageal branches of the left gastric
vessels & Lymphatics from the lower third of
esophagus.
Vena caval opening: lies at the level of T8 in the
central tendon, slightly to the right of median plane.
Transmits: Inferior vena cava & terminal branches of
right phrenic nerve.

14. Minor Openings - unnamed.
1. Superior epigastric vessels pass through the gap (space of Larry) between muscular slips arising from
xiphoid process & 7th costal cartilage.
2. Musculophrenic artery passes through the gap betweenthe slips of origin from 7th to 8th ribs.
3. Lower five intercostal nerves and vessels (i.e., 7th–11th) pass through gaps between the adjoining
costal slips.

15. 4. Subcostal nerves and vessels pass deep to lateral arcuate ligament.
5. Sympathetic chain passes deep to medial arcuateligament.
6. Greater, lesser, and least splanchnic nerves pass by piercing the crus of diaphragm on corresponding
side.
7. Hemiazygos vein pierces the left crus of the diaphragm

16. Nerve Supply
(a) Right & left phrenic nerves: are both motor & sensory
(b) lower five intercostal & subcostal nerves.
Motor nerve supply:
Right & left phrenic nerve: provides motor innervation to
right half & left half of diaphragm.
Sensory nerve supply:
• phrenic Nerve provide sensory innervation to the
central tendon of diaphragm and pleura & peritoneum
related to it.
• Intercostal nerves provide sensory innervation to
peripheral parts of the diaphragm.

17. Arterial Supply
1. Superior phrenic arteries (phrenic
arteries): from thoracic aorta.
2. Inferior phrenic arteries: from abdominal
aorta.
3. Pericardiophrenic arteries: from internal
thoracic arteries.
4. Musculophrenic arteries: terminal
branches of internal thoracic arteries.
5. Superior epigastric arteries: terminal
branches of internal thoracic arteries.
6. Lower five intercostal and subcostal
arteries from the aorta
Veins correspond with the arteries and
drain into the systemic veins.

18. Lymphatic Drainage
1. Anterior diaphragmatic lymph nodes:situated
behind xiphoid process.
2. Posterior diaphragmatic lymph nodes, situated
near aortic orifice.
3. Right lateral diaphragmatic nodes, situated near
the caval opening.
4. Left lateral diaphragmatic nodes, situated near
the esophageal opening.

19. Action of the Diaphragm:
• On contraction,diaphragm pulls down its central tendon and increases the vertical diameter of thorax.
• Contraction of the diaphragm assists the contraction of the muscles of the anterior abdominal wall in
raising the intra-abdominal pressure for micturition, defecation, and parturition.
• On the 3 major openings- during inspiration vena caval opening dilates, oesophageal opening
constricts and aortic opening undergoes no changes.

20. Applied anatomy
• Diaphragmatic paralysis (paralysis of diaphragm):
--Unilateral damage of phrenic nerve leads to unilateral diaphragmatic paralysis. The condition is
diagnosed during fluoroscopy when an elevated hemidiaphragm is seen on the side of lesion, and
showing paradoxical movements.
---Bilateral damage of phrenic nerves leads to complete diaphragmatic paralysis. It may cause respiratory
failure.
• Penetrating injuries can result from stab or bullet wounds to the chest or abdomen.
- Any penetrating wound to the chest below the level of the nipples should be suspected of
causing damage to the diaphragm until proved otherwise
• Hiccups: Occur due to involuntary spasmodic contractions
of the diaphragm accompanied by the closure of the glottis.
--Hiccups normally occur after eating or drinking as a result
of gastric irritation.
---Pathological causes of hiccups include :-
diaphragmatic irritation, phrenic nerve irritation, hysteria.

21. Development
Diaphragm develops in the region of neck from:
1. Septum transversum, ventrally.- Central tendon of diaphragm
2. Pleuroperitoneal membranes at the sides.-Small peripheral
part
3. Dorsal mesentery of esophagus-forms crura of diaphragm
4. Mesoderm of Body wall- Large Peripheral part of diaphragm

22. Diaphragmatic hernias:
 Congenital:
Posterolateral hernia: Herniation occurs through the gap between the
costal and vertebral origins of the diaphragm called foramen of Bochdalek.
--Gap remains due to failure of closure of pleuroperitoneal canal.
--Hernia occurs commonly on the left side
 Acquired:
Hiatal (sliding) hernia: Gastroesophageal junction & cardiac end of
stomach slides up into the thoracic cavity.
---caused by weakness of diaphragmatic muscle surrounding the
esophageal opening & increased intra-abdominal pressure.
--- cause regurgitation of acid contents of stomach into the esophagus
leading to peptic esophagitis.

23. Thank You

24. 1.THE DIAPHRAGM : Present at the junction of thoracic and abdominal cavity.
2 .PELVIC DIAPHRAGM : Present at the junction of abdomen proper above and pelvic
cavity below.
3 .UROGENITAL DIAPHRAGM : Present at the junction of greater pelvis above and
perineum below.
4. DIAPHRAGMA ORIS : This is a muscle bulk formed by the myelohyoid muscle which
bears the weight of the tongue.
5. DIAPHRAGMA SELLA : It covers the pituitary gland,present inside the middle
cranial fossa.