The intercostal nerves enter the intercostal spaces and run forward inferiorly. The first six nerves are distributed within their intercostal spaces, while the 7th-9th enter the anterior abdominal wall and the 10th-11th pass directly into the abdominal wall. There are two anterior and one posterior intercostal artery in each intercostal space, with the anterior arteries originating from the internal mammary or musculophrenic arteries and the posterior originating from the subclavian or descending thoracic aorta. The intercostal veins drain into the brachiocephalic veins, azygos vein, or internal thoracic vein.

1. Nerves and vessels of thoracic
wall
Dr. Rabab Kompal
Vice Principal
Royal Institute of Medical Sciences,
Multan

2. Intercostal nerves
• The intercostal nerves are the anterior rami of
the first 11 thoracic spinal nerves
• The anterior ramus of the 12th thoracic nerve lies
in the abdomin and runs forward in the
abdominal wall as the subcostal nerve
• Each intercostal nerve enters an intercostal space
between the parietal pleura and the posterior
intercostal membrane.
• It then runs forward inferiorly to the intercostal
vessels in the subcostal groove of the
corresponding rib, between the innermost and
internal intercostal muscle.

4. • The first six nerves are distributed within their
intercostal spaces.
• The seventh to ninth intercostal nerves leave
the anterior ends of the intercostal spaces and
enter in anterior abdominal wall.
• The 10th and 11th nerves pass directly into the
abdominal wall

5. • Anterior Intercostal
arteries
• 2 small arteries in each of
the 9 spaces.
• The upper 6 from internal
mammary artery
• The lower 3 from musculo-
phrenic artery
• NB. Internal mammary or
internal thoracic artery is a
branch from1st part of
subclavian artery

6. • Posterior Intercostal
arteries
• One in each of the 11
spaces
• 1st & 2nd arise from
superior Intercostal
artery of costocervical
trunk of 2nd part of
subclavian artery
• The lower 9 arteries &
subcostal artery arise
from descending thoracic
aorta.

7. • In each space the
posterior Intercostal
artery and its collateral
branch anastomose
with the 2 anterior
Intercostal arteries

8. Anterior Intercostal veins
• 2 in each space.
• 9th,8th & 7th join the venae
commitantes of musculo-
phrenic artery
• 6th,5th & 4th join venae
commitantes of internal
mammary artery
• 3rd,2nd &1st join internal
mammary vein
• Internal mammary vein drains
into innominate
(Brachiocephalic vein)

9. Posterior Intercostal veins
• One in each of the 11 spaces.
• On the right:
• 1st drains into Rt. Brachiocephalic v.
• 2nd,3rd & sometimes the 4th unite to form
Rt. Superior Intercostal vein (B) which
drains into azygos vein.
• From 5th to 11th & subcostal veins drain
into azygos vein ©.
• On the Left:
• 1st drains into Lt. iBrachiocephalic V.
• 2nd,3rd& sometimes the 4th join to form
Lt. Superior Intercostal vein which drains
into Lt innominate vein.
• 5th,6th,7th, & 8th form superior
hemiazygos vein to azygos vein
• 9th,10th.11th &Subcostal form inferior
hemiazygos vein to azygos vein.

11. Internal thoracic artery
• Internal thoracic artery supplies the anterior wall
of the body from the clavicle to the umbilicus
• It is a branch of 1st part of the subclavian artery in
the neck
• It descends vertically on the pleura behind the
costal cartilages a fingerbreadth lateral to the
sternum and ends in the 6th intercostal spaces by
dividing into the superior epigastric and
musculophrenic arteries

12. Branches of internal thoracic artery
• 2 anterior intercostal arteries: upper 6 costal space
• Perforating arteries: accompany terminal branches of
the corresponding intercostal nerves
• Percardiacophrenic artery: accompanis the phrenic
nerve and supplies the pericardium
• Mediastinal arteries: contents of anterior mediastinum
• Superior epigastric artery: rectus muscles
• Musculophrenic artery: lower intercostal spaces and
the diaphragm

14. Internal thoracic vein
• Accompanies the internal thoracic artery and
drains into the brachiocephalic vein on each
side

16. Lymph drainage
• Skin of anterior thoracic wall= anterior
axillary nodes
• Skin of posterior thoracic wall= posterior
axillary nodes
• Anterior part of anterior intercostal spaces=
anterior thoracic nodes= thoracic duct,
bronchomediastinal trunk
• Posterior parts of intercostal spaces=
posterior thoracic nodes=thoracic duct