DISSECTION OF THE PECTORAL REGION AND
AXILLA
Make certain you have reviewed
(1) the anatomy of the brachial plexus
B
(2) the branches of the axillary artery
(3) the anatomy of the superficial veins in this
region!!!
C
A
B
BRACHIAL PLEXUS
Musculocut.
Lateral
Anterior
Median
Ulnar
Radial
Axillary
Anterior
Medial
Posterior
Anterior
Upper
Middle
Lower
C5
C6
C7
C8
T1
Brachial
Plexus
.
Axillary
Subclavian
Superior
thoracic
Thoracoacromial
Lateral
thoracic
Anterior
circumflex
humeral
Posterior
circumflex
humeral
Subscapular
Catheter
Circumflex
scapular
Thoracodorsal
Deep brachial
Axillary
Artery
Brachial
Veins
DISSECTION OF
THE PECTORAL
REGION
PECTORAL SKIN INCISIONS
•
Using the following slide as a reference, make the following skin
incisions with the cadaver in the supine position.
•
From the jugular notch A along the clavicle and across the acromion
B to a point about 10 cm distal to the acromion.
•
From A to the xiphisternal junction C.
•
From C laterally to the table.
•
At about mid-arm, make a complete circular incision.
•
At the level of the wrist make another circular incision.
•
Join these two circular incisions with a longitudinal one on the
lateral aspect of the upper limb, that extends to the cut that is
distal to the acromion.. Reflect the skin of the arm and forearm
and remove it completely. DO NOT damage the superficial veins
and cutaneous nerves in the superficial fascia.
PECTORAL
REGION
B
C
A
B
Clean the anterior surface of the pectoralis major muscle and define its
borders. Recall that the pectoralis major muscle has two heads: a clavicular
and sternocostal head. The fibers of the two heads converge and insert into
the lateral lip of the bicipital groove of the humerus.
Identify the cephalic vein piercing the fascia of
the deltopectoral triangle.
When beginning dissection in this region,
recognize and SAVE the thoracoacormial trunk or
artery as it exits the axillary artery
Cut the sternocostal head of pectoralis major muscle
near its attachment to the sternum and the costal
cartilage of the 6th rib and reflect it laterally.
Lateral pectoral nerve
Pectoralis minor m.
Medial pectoral nerve
Serratus anterior m.
The medial and lateral pectoral
nerves are named for the cords of
the brachial plexus from which they
arise and not for their relationship
to
pectoralis minor m..
You should note some branches of
the thracoacromial artery
accompanying these nerves.
Brachial
Plexus
Lateral pectoral nerve
Medial pectoral nerve
.
Identify the borders of the
pectoralis minor m. Cut it near its
attachments to the ribs and reflect
the muscle superiorly towards its
attachment to the coracoid process.
Thorcoacromial a.
As you reflect the
pectoralis minor m., you
should be able to better
view the medial and
lateral poctoral nn. And
the accompanying vessels,
which are branches of
the thoracoacromial
artery.
Remember that the
thoracoacromial a. arises
from the second part of
the axillary a., which is
the portion of the vessel
that lies deep to the
pectoralis minor m.
Subclavius m.
Lateral thoracic a.
Long thoracic n.
This is a good
time to also
identify and save
the lateral
thoracic a., which
also comes off
the second part
of the axillary
a..
It can be found
along the lateral
border of the
pectoralis minor
m. accompanied
by the long
thoracic n. which
innervates the
serratus anterior
m..
Brachial
Plexus
Long thoracic nerve
.
The axilla is described anatomically
as having four walls.
The axilla is described anatomically
as having four walls.
Make certain that the arm is in
an abducted position to facilitate
the cleaning of the nerves and
vessels.
Be careful to NOT cut the
nerves and blood vessels
contained in the axilla as the
superficial fascia is removed.
Identify the axillary artery.
Identify the lateral cord of the
brachial plexus.
Identify the
medial cord
of the
brachial
plexus.
Identify the
posterior
cord of the
brachial
plexus.
Now, clean and identify the
terminal branches of the brachial
plexus.
Coracobrachialis muscle
Musculocutaneous nerve –
arising from the lateral cord
and piercing the
coracobrachialis muscle
Contribution from
lateral cord
Contribution from
medial cord
Median nerve
Recall that the median nerve has contributions from both the lateral
and medial cords of the brachial plexus.
Ulnar nerve –
arising from the
medial cord
You will notice two nerves running adjacent to the ulnar nerve that may arise
separately from the medial cord or from a common trunk – the medial brachial
cutaneous and medial antebrachial cutaneous nerves.
These nerves provide cutaneous innervation to the medial aspect of the arm
and forearm.
Medial cutaneous nerve of the
forearm or medial antebrachial
cutaneous nerve
Medial cutaneous
nerve of the arm
or medial
brachial
cutaneous nerve
Brachial
Plexus
Medial brachial cutaneous nerve
.
Medial antebrachial cutaneous nerve
You may also see the intercostobrachial nerve which actually arises from the
second or third intercostal nerves.It will often communicate with the medial
brachial cutaneous nerve. The intercostobrachial nerve primarily supplies the
skin on the floor of the axilla and some of the adjacent regions of the arm.
Intercostalbrachial
nerve
Lateral pectoral nerve
arising from the lateral cord
Medial pectoral nerve arising
from the medial cord
You should be able to trace the medial and lateral pectoral nerves to
their origins from the medial and lateral cords of the brachial plexus.
Now, let’s take another look at the axillary artery which begins at the lateral
border of the first rib as the continuation of the subclavian artery.
It is described as being made up of three parts relative to the pectoralis
minor muscle.
The first part of the axillary artery
lies between the lateral border of
the first rib and the medial border
of pectoralis minor muscle.
reflected pectoralis
minor muscle
The second part of the axillary artery lies
posterior to the pectoralis minor muscle.
The third part of the axillary
artery lies between the lateral
border of the pectoralis minor
muscle and inferior border of
teres major muscle.
As the axillary artery passes
distal to the teres major
muscle, its name changes to the
brachial artery.
BRANCHES OF THE AXILLARY ARTERY
First Part (located between lateral border of first rib and superior
border of pectoralis minor)
1. superior thoracic artery
Second Part (deep to the pectoralis minor muscle)
1. thoracoacromial trunk or artery
2. lateral thoracic artery
Third Part ( from inferior border of the pectoralis minor muscle to the
inferior border of the teres major muscle)
1. subscapular artery
2. anterior circumflex humeral artery
3. posterior circumflex humeral artery
Axillary
Subclavian
Superior
thoracic
Thoracoacromial
Lateral
thoracic
Anterior
circumflex
humeral
Posterior
circumflex
humeral
Subscapular
Catheter
Circumflex
scapular
Thoracodorsal
Deep brachial
Axillary
Artery
Brachial
Branch of the First Part of the Axillary Artery
Superior thoracic a.
Branches of the Second Part of the Axillary Artery
Thoracoacromial trunk which gives
rise to four branches: (1) deltoid,
(2) acromial, (3) clavicular, and
(4) pectoral
Branches of the Second Part of the Axillary Artery
Thoracoacromial trunk which gives
rise to four branches: (1) deltoid,
(2) acromial, (3) clavicular, and
(4) pectoral
Branches of the Second Part of the Axillary Artery
Lateral thoracic artery which
exits the axillary artery AFTER
the thoracoacromial trunk and
then follows the lateral border
of the pectoralis minor muscle.
Branches of the Third Part
of the Axillary Artery
Branches of the Third Part of the Axillary Artery
Subscapular artery
which is the largest of
the branches of the
axillary artery.
Branches of the Third Part of the Axillary Artery
Subscapular artery
Thoracodorsal artery is a branch
of the subscapular artery.
Circumflex scapular artery is a
branch of the subscapular artery.
Branches of the Third Part of the Axillary Artery
Anterior circumflex humeral
artery which usually travels
deep to the coracobrachialis
muscle and the short head of
the biceps brachii muscle
before anastomosing with the
posterior humeral circumflex
artery.
Branches of the Third Part of the Axillary Artery
Posterior circumflex humeral
artery which is usually the
larger of the two circumflex
arteries.
Make certain that you
have cleaned the
posterior cord of the
brachial plexus.
Radial nerve
Remember that the radial
nerve is simply a
continuation of the
posterior cord.
.
Axillary nerve
You may see the three smaller branches of
the posterior cord of the brachial plexus
lying anterior to the subscapularis muscle
(1) upper subscapular n., (2) lower
subscapular n., and (3) the thoracodorsal n..
Lower subscapular n.
going to subscapularis
and teres major
muscles
Thoracodorsal n..
going to the
latissimus dorsi
muscle
Brachial
Plexus
Upper subscapular nerve
Thoracodorsal nerve
Lower subscapular nerve
.