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The axilla
Dr.Partha Sarathi Ain. MD
The axilla
? Definition: The axil a (armpit)
is a
pyramid-shaped space between the
upper part of the arm and the side of the
chest
? Functions: It forms an important
passage for nerves, blood, and lymph
vessels as they travel from the root of the
neck to the upper limb.
INTRODUCTION
? `Truncated pyramidal'
space between upper
part of arm and chest
wall
? Has 4 walls, apex, base
Boundaries of the axilla
The axilla has an apex, base and 4 wal s
(Anterior, posterior, medial and lateral walls)
Apex of the axil a
? It is the upper end of the
axil a
? It continues into the root
of the neck (posterior
triangle of the neck)
through the cervico-
axillary canal.
? Boundraies of the
cervico-axil ary canal
? In front by the clavicle,
? Behind by the upper
border of the scapula,
? Medial y by the outer
border of the first rib
Base of the axilla
? It is the lower end of the axilla.
? The base is formed by the skin stretching between the
anterior and posterior walls.
? Boundaries:
? In front by the anterior axillary fold (formed by
the lower border of the pectoralis major muscle),
behind by the posterior axillary fold (formed by
the tendon of latissimus dorsi and the teres major
muscle), medial y by the chest wall
Walls of the Axilla
The walls of the axilla are made up as follows:
? Anterior wall: By the pectoralis major, subclavius, and pectoralis
minor muscles.
? Posterior wall: By the subscapularis, latissimus dorsi, and teres
major muscles.
Walls of the Axilla
The walls of the axilla are made up as follows:
? Medial wal : By the upper four or five ribs and the intercostal spaces
covered by the serratus anterior muscle.
? Lateral wall: By the coracobrachialis and biceps muscles in the
bicipital groove of the humerus.
? Anterior wall: By the pectoralis major, subclavius,
and pectoralis minor muscles, clavipectoral fascia.
cervico axil ary canal
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Structures passing through apex
? Axillary vessels
? Cords of BP
? Long thoracic Nerve
? LN efferents
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? Posterior wall: By the subscapularis, latissimus
dorsi, and teres major muscles.
? Medial wall:
By the upper four or
five ribs and the
intercostal spaces
covered by the
serratus anterior
muscle
Contents of the axilla
? Axillary artery
? Axillary vein
? Brachial plexus
? Axillary lymph nodes
Base
?Concavity directed below
?Boundaries
? Ant : anterior axil ary fold
? Post: posterior axil ary fold
? Medial: Chest wal
? Lateral: arm
?Formed by: skin, superficial fasciae, & deep fascia
?Deep fascia: axil ary fascia extending between Pectoralis
Major (ant fold) and Lat Dorsi & Teres Major (post fold)
?Supported by Suspensory lig of Axil a
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Axil ary Artery
? Beginning: The axil ary artery begins at the lateral
border of the first rib as a continuation of the
subclavian artery
? Termination: at the lower border of the teres major
muscle, where it continues as the brachial artery.
? The artery is closely related to the cords of the
brachial plexus and their branches and is enclosed
with them in a connective tissue sheath called the
axil ary sheath. If this sheath is traced upward into
the root of the neck, it is seen to be continuous with
the prevertebral fascia
Parts of the axil ary artery
? The pectoralis minor
muscle crosses in front
of the axil ary artery and
divides it into three parts:
? First part above the
pectoralis minor muscle
? Second part behind the
pectoralis minor muscle
? Third part below the
pectoralis
minor muscle
First Part of the Axillary Artery
? This extends from the lateral border of the first rib to the
upper border of the pectoralis minor.
Relations
? Anteriorly: The pectoralis major and the skin.
? Posteriorly: The long t
thoracic nerve (nerve to
the serratus anterior)
? Lateral y: The three cords
? of the brachial plexus
? Medial y: The axillary vein
Second Part of the Axillary Artery
? This lies behind the pectoralis minor muscle.
Relations
? Anteriorly: The pectoralis minor, the pectoralis major, and the
skin
? Posteriorly: The posterior
cord of the brachial plexus,
the subscapularis muscle,
and the shoulder joint.
? Lateral y: The lateral cord
of the brachial plexus.
? Medial y: The medial cord
of the brachial plexus and
the axillary vein.
Third Part of the Axillary Artery
? This extends from the lower border of the pectoralis minor to the
lower border of the teres major.
? Relations
? Anteriorly: The pectoralis major for a short distance; lower down the artery is
crossed by the medial root of the median nerve.
? Posteriorly: The subscapularis,
the latissimus dorsi, and the teres
major. The axil ary and radial nerves
also lie behind the artery.
? Lateral y: The coracobrachialis,
the biceps, and the humerus.
The lateral root of the median
and the musculocutaneous nerves
also lie on the lateral side.
? Medially: The ulnar nerve,
the axil ary vein, and the medial
cutaneous nerve of the arm.
Branches of the Axil ary Artery
From the first part:
? The superior (highest) thoracic artery is small and runs
along the upper border of the pectoralis minor.
From the second part:
? 1.The thoracoacromial
artery immediately divides into
terminal branches.
? 2.The lateral thoracic artery runs along the lower border of the
pectoralis minor
From the third part:
? 1. The subscapular artery runs along the lower border of
the subscapularis muscle.
? 2. The anterior circumflex humeral artery
wind around the
front of the surgical neck of the humerus.
? 3. posterior circumflex humeral artery wind around the
back of the surgical neck of the humerus
Axillary Vein
? The axil ary vein is formed at the lower border
of the teres major muscle by the union of the
venae comitantes of the brachial artery and the
basilic vein.
? It runs upward on the medial side of the axillary
artery and ends at the lateral border of the first
rib by becoming the subclavian vein.
? The vein receives tributaries, which correspond
to the branches of the axillary artery, and the
cephalic vein
Lymph
drainage of
upper limb.
Axillary lymph nodes
20-30 in number, embedded in the fibro fatty tissue of Axilla Drain
v Lateral part of breast.
v Superficial lymphatic vessels from thoraco lumbar region above level
of umbilicus. Approx 75% of lymph from breast is drained to axillary
group of LNs, making them important for diagnosis of cancer by
biopsy. Axillary LNs are of 05 groups.
v Whole of upper limb except lateral side of arm, forearm, hand.
v Due to the surgical removal of metastasized axillary LNs in case of Ca-
breast chance of lymphoedema is very high.
v In case of surgical management of Ca-breast draining LNs are usually
removed to prevent recurrence of further metastasis.
Axillary lymph nodes
ANTERIOR; (pectoral) along medial wall with Lateral Thoracic vein
POSTERIOR: (Subscapular ) along medial wall with Subscapular vein
LATERAL: along medial side of axillary vein CENTRAL:
in
Centre of Axillary fat, Related to Intercostobrachial Nv.
APICAL: at apex of Axilla.
INFRACLAVICULAR: on Clavipectoral fascia in deltopectoral groove.
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This post was last modified on 12 August 2021