Axilla boundaries and content

7/30/2019 Axilla boundaries and content

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AXILLA(Boundaries & Content)

By

Dr Raza YounusGeneral Surgeon

Assistant ProfessorDepartment of Anatomy

Avicenna Medical College


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AXILLA

Axilla

The axilla is the pyramidal space

inferior to the Glenohumeral joint

superior to the Axillary fasciaat the junction of the arm and thorax

The axilla provides a passageway or distribution center,

usually protected by the adducted upper limb,for the neurovascular structures that serve the upper

limb.


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Axilla

AxillaFrom this distribution center, neurovascular structures pass

(1) superiorly via the cervicoaxillary canal to (or from) the root of the neck,

(2) anteriorly via the clavipectoral triangle to the pectoral region,

(3) inferiorly and laterally into the limb itself,

(4) posteriorly via the quadrangular space to the scapular region

(5) inferiorly and medially along the thoracic wallto the inferiorly placed axioappendicular muscles

(serratus anterior and latissimus dorsi).


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AXILLA

The axilla has an apex, a base, and four walls, three of which aremuscular:

APEX:

The apex of axilla is the cervicoaxillary canal,

the passageway between the neck and the axilla,

bounded by the 1st rib, clavicle, and superior edge of the scapula.

The arteries, veins, lymphatics, and nerves traverse this superior

opening of the axilla to pass to or from the arm


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AXILLA

BASE:The base of axilla is formed by the

concave skin, subcutaneous tissue, and axillary(deep) fascia extending from the arm to the thoracic

wall (approximately the 4th rib level), forming the axillary fossa (arm pit).

The base of the axilla or axillary fossa is bounded by the

-- anterior and posterior axillary folds,

-- thoracic wall,

-- medial aspect of the arm


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AXILLA

ANTERIOR WALL:

Has two layers, formed by the

-- pectoralis major

-- pectoralis minor

-- pectoral and clavicopectoral fascia associated with them

Anterior axillary fold

is the inferiormost part of the anterior wall

that may be grasped between the fingers;

it is formed by the

pectoralis major, as it bridges from thoracic wall tohumerus, and the overlying integument


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AXILLA

POSTERIOR WALL:

is formed chiefly by the

-- scapula and subscapularis on its anterior surface

-- inferiorly by the teres major and latissimus dorsi

Posterior axillary fold

is the inferior most part of the posterior wall that may be grasped.

It extends farther inferiorly than the anterior wall and is

formed by

-- latissimus dorsi, teres major, and overlying integument.


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AXILLA

MEDIAL WALL:is formed by the

-- thoracic wall 1st - 4th ribs

-- intercostal muscles

-- overlying serratus anterior

LATERAL WALL:

is a narrow bony wall

formed by the

-- intertubercular groove in the humerus.


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CONTENTS OF AXILLA

CONTENTS OF AXILLA:

axillary blood vessels (axillary artery and its branches, axillary vein and itstributaries),

lymphatic vessels, and

several groups ofaxillary lymph nodes,

all embedded in a matrix ofaxillary fat

large nerves that make up the cords and branches of the brachial plexus,

a network of interjoining nerves that pass from the neck to the upper limb.

Proximally, these neurovascular structures are ensheathed in a sleeve-likeextension of the cervical fascia, the axillary sheath


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Axillary Artery

Axillary Arterybeginsat the lateral border of the 1st rib

as the continuation of the Subclavian artery

ends

at the inferior border of the teres major

It passes posterior to the pectoralis minor into the arm and

becomesBrachial artery

(when it passes the inferior border of the teres major

at which point it usually has reached the humerus).


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Axillary Artery

Axillary artery is divided into three parts

by the pectoralis minor

(the part number also indicates the number of itsbranches):

First part of the axillary artery

is located between the

lateral border of the 1st rib and the

medial border of the pectoralis minor;it is enclosed in the axillary sheath

has one branch the

1) superior thoracic artery.


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Axillary Artery

The second part of the axillary arterylies posterior to pectoralis minor and

has two branches:1) Thoracoacromial

2) Lateral thoracic arteries


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Axillary Artery

The third part of the axillary artery

extends from the lateral border of pectoralis minor to the

inferior border of teres major

has three branches.

1. The subscapular artery

is the largest branch of the axillary artery.

2. Anterior circumflex humeral

3. Posterior circumflex humeral arteries

arise sometimes by means of a common trunk.


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Axillary Artery

The superior thoracic artery

is a small, highly variable vessel that arises just inferior to thesubclavius.

It commonly runs inferomedially posterior to the axillary vein

and supplies the subclavius, muscles in the 1st and 2ndintercostal spaces, superior slips of the serratus anterior, andoverlying pectoral muscles.

It anastomoses with the intercostal and/or internal thoracicarteries.


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Axillary Artery

The thoracoacromial artery,

a short wide trunk, pierces the costocoracoid membrane

divides into four branches, deep to the clavicular head of the pectoralis major

acromial, deltoid, pectoral, and clavicular

Lateral thoracic artery

has a variable origin.

It usually arises as the second branch of the second part of the axillary artery anddescends along the lateral border of the pectoralis minor, following it onto thethoracic wall

it may arise instead from the thoracoacromial, suprascapular, or subscapular arteries.

The lateral thoracic artery supplies the pectoral, serratus anterior, and intercostalmuscles, the axillary lymph nodes, and the lateral aspect of the breast.


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Axillary Artery

The subscapular artery,the branch of the axillary artery with the greatest

diameter but shortest length descends along

the lateral border of the subscapularis on theposterior axillary wall.

It soon terminates by dividing into the Circumflex scapular

Thoracodorsal arteries.


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Axillary Artery

The circumflex scapular artery,

often the larger terminal branch of the subscapular artery,(curves posteriorly around the lateral border of the scapula,

passing posteriorly between the subscapularis and the teresmajor to supply muscles on the dorsum of the scapula).

It participates in the anastomoses around the scapula.

The thoracodorsal artery

continues the general course of the subscapular artery to the

inferior angle of the scapula and supplies adjacent muscles,principally the latissimus dorsi.

It also participates in the arterial

anastomoses around the scapula.


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Axillary Artery

The circumflex humeral arteries

Encircle the surgical neck of the humerus, anastomosingwith each other.

a) Anterior circumflex humeral artery

passes laterally, deep to the coracobrachialis and biceps brachii.

It gives off an ascending branch that supplies the shoulder.

b) Larger Posterior circumflex humeral artery

passes medially through the posterior wall of the axilla

via the quadrangular space with the axillary nerve

to supply the glenohumeral joint and surrounding muscles (e.g.,

the deltoid, teres major and minor, and long head of the triceps)


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Axillary Vein

Axillary Vein

The axillary vein lies initially (distally) on the anteromedial side of theaxillary artery, with its terminal part anteroinferior to the artery

This large vein is formed by the union of the

--Brachial vein (the accompanying veins of the brachial artery)

-- Basilic vein at the inferior border of the teres major.

The axillary vein is described as having three parts that correspond tothe three parts of the axillary artery.

Thus the initial, distal end is the third part, whereas the

terminal, proximal end is the first part.

The axillary vein (first part) ends at the lateral border of the 1st rib,

where it becomes the subclavian vein.


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Axillary Vein

The veins of the axilla are more abundant than the arteries, are highly variable,

and frequently anastomose.

The axillary vein receives tributaries that generally correspond to branches ofthe axillary artery with a few major exceptions:

The veins corresponding to the branches of the thoracoacromial artery do not

merge to enter by a common tributary; some enter independently into theaxillary vein, but others empty into the cephalic vein, which then entersthe axillary vein superior to the pectoralis minor, close to its transitioninto the subclavian vein.

The axillary vein receives, directly or indirectly, the thoracoepigastric vein(s),

which is(are) formed by the anastomoses of superficial veins from theinguinal region with tributaries of the axillary vein (usually the lateralthoracic vein).

These veins constitute a collateral route

that enables venous return in the presence of obstruction of the inferior venacava


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AXILLA(Boundaries & Content)

By

Dr Raza YounusGeneral Surgeon

Assistant Professor

Department of Anatomy

Avicenna Medical College


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Axillary Lymph Nodes


The fibrofatty connective tissue of the axilla (axillaryfat) contains many lymph nodes.

The axillary lymph nodes are arranged in five principalgroups:

pectoral, subscapular, humeral, central, and apical.

The groups are arranged in a manner that reflects thepyramidal shape of the axilla


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Three groups of axillary nodes are related to the triangular base,

one group at each corner of the pyramid:

The pectoral (anterior) nodes

consist of three to five nodes that

lie along the medial wall of the axilla,

around the lateral thoracic vein and the

inferior border of the pectoralis minor.

The pectoral nodes receive lymph mainly from the

anterior thoracic wall, including most of the breast

(especially the superolateral [upper outer] quadrant andsubareolar plexus)


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The subscapular (posterior) nodes

consist of six or seven nodes thatlie along the posterior axillary fold and subscapular

The humeral (lateral) nodes

consist of four to six nodes that

lie along the lateral wall of the axilla,medial and posterior to the axillary vein.

These nodes receive nearly all the lymph from the upper limb,

except that carried by the lymphatic vessels accompanying the cephalic vein,

which primarily drain directly to the apical axillary and infraclavicularnodes.

Efferent lymphatic vessels from these three groups

pass to the central nodes.


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Central Nodes:

The central nodes are three or four large nodessituated deep to the pectoralis minor near the base of the axilla,

in association with the second part of the axillary artery.

Apical Nodes:

Efferent vessels from the central nodes pass to the apical nodes.

The apical nodes are located at the apex of the axilla

along the medial side of the axillary vein and

the first part of the axillary artery.

The apical nodes receive lymph from

-- all other groups of axillary lymph nodes-- from lymphatics accompanying the proximal cephalic vein.

Efferent vessels from the apical group of nodes

traverse the cervicoaxillary canal.


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These efferent vessels ultimately unite to form the

Subclavian lymphatic trunk,

although some vessels may drain en route through the

Clavicular (infraclavicular and supraclavicular) nodes.

Once formed, the subclavian trunkon the right side

may be joined by thejugular and bronchomediastinal trunks

to form the right lymphatic duct,

it may enter the right venous angle independently.

On the left side,

the subclavian trunk most commonly joins the thoracic duct


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Axilla boundaries and content

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