INTERCOSTAL SPACES
MISS OMOTOLA BADA
200L MEDICAL STUDENTS
EKO UNIMED
INTERCOSTAL SPACES
• They are occupied by
intercostal muscles.
• The superficial layer is
formed by the external
intercostals.
• The deeper layer is
formed by the internal
intercostals.
• The deepest fibres of the
internal intercostals lie
deep to the intercostal
vessels and nerves
INTERCOSTAL SPACES
• These are designated as
a seperate muscle and
they are referred to as
INNERMOST
INTERCOSTAL MUSCLE.
• It contains intercostal
muscles, neurovascular
bundles and lymphatics.
EXTERNAL INTERCOSTAL MUSCLES
• They are 11pairs.
• They occupy the
intercostal spaces from
the tubercules of the ribs
posteriorly to the
costochodral junctions
anteriorly.
• Anteriorly, the muscles
are replaced by the
EXTERNAL INTERCOSTAL
MEMBRANES
EXTERNAL INTERCOSTAL MUSCLES
CONT’D
• They run inferoanteriorly from the rib
above to the rib below.
• SUPERIORLY: It attaches
to the inferior border of
the rib above.
• INFERIORLY:I t attaches
to the superior border
of the rib below.
EXTERNAL INTERCOSTAL MUSCLES
CONT’D
• They are continous
inferiorly with the
external oblique muscle
in the anterolateral
abdominal wall.
• They are active during
inspiration.
INTERNAL INTERCOSTAL MUSCLES
CONT’D
• They are 11pairs
• They run deep to and at
right angles to the
external intercostals.
• SUPERIORLY: It attaches
to the inferior border of
the rib above.
• INFERIORLY:I t attaches to
the superior border of the
rib below
INTERNAL INTERCOSTAL MUSCLES
CONT’D
• ANTERIORLY: It attaches
to the bodies of the ribs
and their costal cartilages.
• POSTERIORY: It attaches
to the angle of the ribs.
• INTERNAL INTERCOSTAL
MEMBRANE: It replaces
the internal intercostal
muscle posterioly
between the ribs medial
to the angles.
INTERNAL INTERCOSTAL MUSCLE
CONT’D
• The inferior intercostal
muscles are continous
with the internal
oblique muscle in the
anterolateral abdominal
wall.
• They are weaker than
the external intercostal
INTERNAL INTERCOSTAL MUSCLES
CONT’D
• They are most active
during expiration.
INNERMOST INTERCOSTAL MUSCLES
• They are similar to the
internal intercostals.
• They are their deeper
parts.
• They are seperated from
the internal intercostals
by intercostal nerves and
vessels.
INNERMOST INTERCOSTAL MUSCLE
• SUPERIORLY: It attaches
to the inferior border of
the rib above.
• INFERIORLY:It attaches to
the superior border of the
rib below.
• These muscles pass
between the internal
surfaces of adjacent ribs
and occupy the lateral
region of the intercostal
spaces.
SUBCOSTAL MUSCLES
• They are variable in size
and shape been well
developed ONLY in the
thoracic wall.
• Their slips extend from
the internal surface of
the angle of one rib to
the internal surface of
the second or third rib
inferior to it.
SUBCOSTAL MUSCLES CONT’D
• They run in the same
direction as the internal
intercostals and blend
with them
TRASVERSUS THORACIS MUSCLES
• They consist of four and
five slips that radiate
superolaterally from the
posterior aspect .
• They are continous
inferiorly with the
transversus abdominis
muscles in the
anterolateral body wall.
INTERCOSTAL NERVES
• They are formed from
the anterior rami of
nerves T1-T12.
• They run along the
extent of the intercostal
spaces.
• The anterior ramus of
nerve T12,coursing
inferior to the 12th rib,
is SUBCOSTAL NERVE.
TYPICAL INTERCOSTAL NERVE
3rd -6th intercostal nerves
• They enter the medial
most parts of the
posterior intercostal
spaces running within
the endothoracic fascia
between the parietal
pleura and the internal
intercostal membrane.
TYPICAL INTERCOSTAL NERVES
• Near the angles of the
ribs, the nerves pass
between the internal
intercostal and
innermost intercostal
muscles from here, they
continue in or just
inferior to the costal
grooves running inferior
to the artery.
TYPICAL INTERCOSTAL NERVES
• Collateral branches of
these nerves arise near
the angles of the ribs.
• Anteriorly, they
continue between the
internal and the
innermost intercostal
muscle also supplying
them and other
muscles.
TYPICAL INTERCOSTAL NERVES
• It gives the lateral
cuteneous branches
approximately at the
mid axillary line.
• Anteriorly, it appers on
the internal surface of
the internal intercostal
muscle.
TYPICAL INTERCOSTAL NERVE
• Near the sternum, the
nerves turn anteriorly,
passing between the
costal cartilages to
become ANTERIOR
CUTANEOUS
BRANCHES.
BRANCHES OF THE TYPICAL
INTERCOSTAL NERVE
• Rami communicantes or
communicating branch.
• Collateral branches
supplying intercostal
muscles and parietal
pleura.
• Lateral cutaneous
branches divides into
anterior and posterior
branches supplying skin
of the lateral thoracic and
abdominal walls
BRANCHES OF THE TYPICAL
INTERCOSTAL NERVE
• Anterior Cuteneous
Branches: Supply skin on
the anterior aspect of the
thorax and abdomen.
• Muscular Branches:
Supply the
intercostal,subcostal,tran
sversus thoracis,levatore
costarum and serratus
posterior muscles.
ATYPICAL INTERCOSTAL NERVE
• 1st and 2nd intercostal
nerves course on the
internal surface of the 1st
and 2nd ribs instead of
along the inferior margin
in the costal grooves.
• The 1st intercostal nerve
has no anterior cutaneous
branch and often no
lateral cutaneous nerve.
ATYPICAL INTERCOSTAL NERVE
CONT’D
• The 2nd intercostal nerve
gives rise to a large lateral
cutaneous branch,
INTERCOSTOBRACHIAL
NERVE.
• The lateral cutaneous
branch of the 3rd
intercostal nerve gives
rise to the 2nd
intercostobrachial nerve.
ATYPICAL INTERCOSTAL NERVE
CONT’D
• 7th -11th intercostal
nerves, after giving rise
to lateral cutaneous
branches, cross the
costal margin and
continue to supply
abdominal skin and
muscles.
ATYPICAL INTERCOSTAL NERVE
CONT’D
They are no longer
between the ribs
(intercostal) but
become THORACOABDOMINAL NERVES.
INTERCOSTAL ARTERIES
• They course through
the thoracic wall
between the ribs with
the exception of the
10th and 11th intercostal
spaces.
• Each intercostal space is
supplied by 3 arteries.
INTERCOSTAL ARTERIES
• One large posterior
intercostal (and its
collateral branch) and a
small pair of anterior
intercostal arteries.
POSTERIOR INTERCOSTAL ARTERIES
• 1st & 2nd arises from the
Superior intercostal
artery, a branch of the
costocervical trunk of
the subclavian artery.
• 3rd -11th intercostal
spaces and subcostal
artery and space arises
posteriorly from the
thoracic aorta.
POSTERIOR INTERCOSTAL ARTERIES
• They all give off a
posterior branch that
accompanies the
posterior ramus of the
spinal nerve to supply
• Spinal Cord
• Vertebral Column
• Back muscles
• Skin
POSTERIOR INTERCOSTAL ARTERY
CONT’D
• They give rise to a small
collateral branch that
crosses the intercostal
spaces and runs along
the superior border of
the rib below.
• They have collateral
branches that
anastomose anteriorly
with anterior intercostal
arteries.
ANTERIOR INTERCOSTAL ARTERIES
• They are branches of the
internal thoracic artery
• It supplies the anterior
part of the upper nine
intercostal spaces.
COURSE
They pass laterally in the
intercostal space, one,
near the inferior margin
of the superior rib
ANTERIOR INTERCOSTAL ARTERIES
• The other near the
superior margin of the
inferior rib.
• The arteries of the 1st
two intercostal spaces
lie initially in the
endothoracic fascia that
lines the thoracic wall
between the parietal
pleura and the internal
intercostal muscles.
ANTERIOR INTERCOSTAL ARTERIES
• The arteries supplying the
3rd-6th intercostal spaces
are seperated from the
pleura by slips of
transversus thoracis
muscle.
• The arteries of the 7th -9th
spaces derive from
MUSCULOPHRENIC
ARTERIES ,also branches
of the internal thoracic
arteries.
ANTERIOR INTERCOSTAL ARTERIES
• The arteries of the 7th-9th
spaces supply the
intercostal muscles and
send branches through
them to supply pectoralis
muscles, breast and skin.
• They are absent from the
inferior 2 intercostal
spaces which are supplied
by the posterior
intercostal arteries and
their collateral branches.
INTERCOSTAL VEINS
• They accompany the
intercostal arteries and
nerves and lie most
superior in the costal
grooves.
• There are 11 posterior
intercostal veins and 1
subcostal vein on each
side
INTERCOSTAL VEINS
• The posterior intercostal
vein anastomose with the
anterior intercostal
veins(tributaries of
internal thoracic veins)
• 4-11th posterior
intercostal vein ends in
the
AZYGOUS/HEMIAZYGOU
S VENOUS SYSTEM.
INTERCOSTAL VEINS
• This conveys blood to
the SVC.
• The posterior
intercostal vein of the
1st intercostal space
enters directly into the
right and left
brachiocephalic veins.
INTERCOSTAL VEINS.
• The posterior
intercostal veins of the
2nd,3rd and occasionally
4th intercostal spaces
uinite to form a trunk
THE SUPERIOR
INTERCOSTAL VEIN.
INTERCOSTAL VEINS
• The superior intercostal
vein is the final
tributary of azygous
vein before it enters the
SVC.
• The left superior
intercostal vein empties
into the left
brachilcephalic vein.
LYMPHATIC DRAINAGE
Lyphm vessels of the
intercostal space
conform to the general
rule,that deep
lymphatics follow
arteries.
Anteriorly drain into
anterior intercostal
nodes that lie along
internal thoracic artery.
LYMPHATICS CONT’D
• Posteriorly drain into
posterior intercostal
nodes that lie in the
posterior mediastinum.
CLINICAL ANATOMY
• INTERCOSTAL NERVE
BLOCK:
It is Local anesthesia of
an intercostal space and is
produced by injecting an
anesthetic agent around
the intercostal nerves
between the
paravertebral line and the
area of required
anesthesia.
CLINICAL ANATOMY
• The procedure, is
commonly used in
patients with rib
fractures and
sometimes after
thoracic surgery.
• It involves infiltration of
the anesthetic around
the intercostal nerve
trunk and its collateral
branches
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