Download THE AXILLA (Arm pit )

‫أ‪.‬د‪.‬عبد الجبار الحبيطي‬
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Is a pyramidal space between the upper part
of the arm & the lateral thoracic wall.It has 4
walls (anterior,posterior,medial & lateral ), apex
& base.The apex is pointed upward in the
direction of the root of the neck (to receive the
brachial plexus) & communicates with the
superior aperture ( Inlet of thorax) of thorax to
receive the axillary artery ( continuity of
subclavian artery).The apex is known as
Cervico-axillary canal & has bony boundaries
which are :
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1-The clavicle anteriorly.
2-Outer border of the first rib medially
3-Upper part of the scapula posteriorly
It allows the passage of the Neuro-vascular
bundle( brachial plexus & Axillary artery) to
the upper limb .
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The base : Is formed by skin & superficial
fascia of the axilla,it is concave when the
limb is beside the trunk & becomes flat &
straight on raising and abducting the limb
due to suspensory ligament of the axilla.
The anterior wall is formed by the
clavicle, 3 muscles ( pectoralis major &
minor Ms in addition to the subclavius M )
and the Clavi-pectoral fascia
Muscle
Origin
Insertion
Nerve supply
Pectoralis Major
1-Side of sternum (sternal)
outer lip of the
intertubercular
groove
Medial & lateral
pectoral Ns
Coracoid process of
scapula
medial pectora
2-Medial 2 /3 of
anterior Border of
clavicle (Clavicular
head)
Pectoralis minor
from 3rd – 5th ribs
Near their costal
cartilages
Subclavius
from costal cartilage subclavius groove
on inferior surface of
of the first rib
clavicle
N. to subclavius
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The clavipectoral fascia: Is part of the deep
fascia attached to the clavicle,it encloses
the subclavius M,then descends down ward
deep to pectoralis major & enclosing
pectoralis minor M & ends as suspensory
ligament of the axilla.It is pierced by the
following structures:
1-Lateral pectoral nerve.
2-Cephalic vein .
3-Pectoral branch of thoracoacromial artery.
4-Some lymphatic vessels.
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The lateral border of pectoralis major M forms
the anterior fold of the axilla.
The posterior wall of the axilla is formed by 3
muscles, these are subscapularis, teres major &
latissimus dorsi Ms.The posterior fold by latissimus
dorsi & teres major Ms
Subscapularis takes origin from the subscapular
fossa& inserts into the lesser tuberosity of the
humerus.It is innervated by upper & lower
subscapular nerves ( from post.cord ).
Teres major takes origin from posterior surface of
lateral border of scapula near the inferior angle &
is inserted in to the medial lip of intertubercular
groove.It is innervated by the lower subscapular
nerve .
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Latissimus dorsi takes origin from the
following sites:
A-Spines of T 7 __T 12 vertebrae.
B-Thoracolumbar fascia.
C-Iliac crest of the Hip bone.
D-Inferior angle of scapula
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The muscle is inserted into the floor of
intertubercular ( Bicepital0 groove & is
innervated by the middle subscapular (
Thoracodorsal ) nerve.
The medial wall is formed by the upper 4-5
ribs,their intercostal spaces& the upper part of
serratus anterior muscle covering them,which
arises from the outer surfaces of upper 8-9
ribs& is inserted into the anterior aspect of the
medial(vertebral ) border of the scapula.It is
innervated by the long thoracic nerve( C 5—C
7).
The lateral wall is formed by the intertubercular
( Bicepital ) groove containing the
corachobrachialis M & short head of Biceps..
1-The axillary vessels: The axillary artery,starts as the 
continuity of the subclavian artery at the outer border of the
first rib& ends at the lower border of teres major M( the lower
limit of the axilla),where it continue as the Brachial artery.It is
crossed by the pectoralis minor M ,which divides it into 3
parts.The first part between outer border of first rib & the
upper border of pectoralis minor M( it gives a single branch
known as highest thoracic or superior thoracic A ).The second
part lies behind pectoralis minor M& is related to the 3 cords
of the brachial plexus* laterally to lateral cord, medialy to medial
cord & posteriorly to the posterior cord) ,while anteriorly it is
related to pectoralis minor M.It gives 2 branches, the
thoracoacromial & lateral thoracic .The thoracoacromial gives
4 branches ,2 of them to bones ( acromial & clavicular) & other
2 to muscles (Deltoid & pectoral branches).While the lateral
thoracic branch descends to the side of the chest wall to
accompany the long thoracic nerve within the substance of
serratus anterior muscle..
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The third part of the axillary artery extends
from lower border of pectoralis minor to
lower border of teres major muscle,where
it continues as the Brachial artery,it is
related to the derivatives of the 3 cords of
the brachial plexus & it gives 3 branches
these are subscapularis ( bifurcates into
thoracodorsal & circumflex scapular
branches ) ,anterior & posterior circumflex
humeral arteries around the surgical neck of
the humerus.
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2-The Brachial plexus:It is formed by the
ventral rami of lower 4 cervical nerves &
the ventral ramus of the first thoracic
nerve.The first stage is roots arrangement
to form trunks ( C 5& 6th form the upper
trunk , C 7 alone forms the middle
trunk,while C 8 & T 1 form the lower (
inferior ) trunk.
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The second stage is the splitting of each
trunk to form anterior & posterior divisions.
The third stage is the formation of the 3
cords by the Re-union of these
divisions.The posterior divisions of the 3
trunks unite to form the posterior cord,the
anterior division of the upper & middle trunks
unite to fornm the lateral cord,while the
anterior division of inferior trunk forms the
medial cord of the brachial plexus.
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The last stage is the derivatives of each
cord as follows:
The posterior cord gives off:
1-Upper subscapular.
2-Middle subscapular ( Thoracodorsal ).
3-Lower subscapular .
4-Axillary nerve.
5- Radial nerve.
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The letral cord gives the following
derivatives:
1-Lateral pectoral nerve.
2-Musculocutaneous nerve.
3-Lateral root to median nerve.
The medial cord gives:
1-Medial pectoral nerve.
2-Medial cutaneous of Arm.
3- Medial cutaneous of forearm.
4-Ulnar nerve.
5- Medial root to median nerve.
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In addition to these derivatives ,the upper
trunk gives 2 branches suprascapular &
nerve to subclavius muscle,while the roots
gives dorsal scapular & long thoracic
nerve) C5-7)
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3-The axillary lymph nodes which are arranges
in the following groups:
A-Anterior ( pectoral ) group,under anterior
border of pectoralis major M.
B-Posterior ( subscapular ) group along the
course of subscapular vessels.
C-Central group within the loose areolar
tissueof the base of the axilla.
D-Lateral group along the course of the axillary
V near bicipital groove.
E-Medial group along the course of lateral
thoracic vein.
F-Apical group in the apex of the axilla,it
receives lymphatics from the above groups &
takes them ( direct them ) to the deep cervical
nodes in the root of the neck.
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Is rudimentary in male & well developed in the
female specially in lactating woman.It is a modified
sweat gland located under the superficial fascia
covering the pectoral region& lying on the deep
fascia covering pectoralis major & part of the
serratus anterior Ms.It extends from the sde of the
sternum medially to the anterior axillary fold laterally(
part of it extends into the axilla as axillary tail of the
breast),while supero-inferiorly it extends from the
level of 2nd rib to the 6th rib.The gland consists of 1520 lobes extending from the periphery of the gland
to the area near the nipple.Each lobe has its own
duct( lactiferous duct) which opens externally in to
the nipple( has about 15-20 openings).The nipple is a
small conical projecting part surrounded by a lighter
area ( Areola).The breast is supplied by:
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1-Pectoral branch of thoracoacromial artery.
2-Mammary branches from the lateral
thoracic artery.
3-Perforating branches from the internal
thoracic artery(i.e internal mammary A ).
4-Branches from intercostal arteries for the
spaces 3rd-5th.
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Rotater Cuff Muscles: are 4 in number
surrounding the capsule of the shoulder joint
to support &share in stabilizing the shoulder
joint.One of these Ms inserts into the lesser
tuberosity ( Subscapularis ),the other 3 are
inserted into the greater tuberosity (
Supraspinatous,infraspinatous & teres minor
muscles)
Muscle
Origin Insertion
Nerve supply
Supraspinatou from
supraspinous
s
fossa Of the
scapula
into the
Suprascapular
superior facet N
of the greater
tuberosity
Infraspinatous from
infraspinous
fossa
from
Teres minor
posterior
aspect of
lateral
Border of
scapula just
above the
middle facet
of greater
tuberosity
inferior facet
of = = =
Suprascapular
N
Axillary N
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The muscles responsible for Abduction
movement of the arm at shoulder joint are:
1-From 0 – 18 degree by Supraspinatous
muscle.
2-18—90 degree by Deltoid
muscle(innervated by the Axillary nerve ).
3-Beyond 90 degree & above the head is by
Trapezius & Serratus anterior muscles.
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The muscles attaching the limb to the back
are by Trapezius,Rhomboid minor,Rhomboid
major, Levaetor scapula & Latissimus
dorsi.
The latissimus dorsi id active during
swimming , climbing, rowing ,pulling &
scratching the opposite scapular region.
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The Trapezius takes origin from the
following sites:
a-From medial third of the superior nuchal
line.
b-From ligamentum nuchae.
c-From the spine of C 7 vertebra
d-From spines of T1 –T 12 vertebrae( T =
Thoracic ).
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The M is inserted into the front of lateral third of
the clavicle,acromion process & upper lip of the
spine of the scapula.It is innervated by the spinal
root of accessory nerve( 11th cranial nerve)which
is motor ,while proprioception sensations from
C4 & C5 nerves.
Levaetor scapula takes origin from transverse
processes of upper 4 cervical vertebrae.
It is inserted in the area around the superior
angle of scapula.
It is innervated by dorsal scapular nerve from
the ventral ramus of C 5.
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Rhomboideus minor takes origin from the
spines of C 7 & T 1 vertebrae.
It is inserted into dorsal aspect of vertebral
border of scapula at the base of the spine.
Is innervated by dorsal scapular nerve.
Rhomboideus major arises from the spines
of T 2 – T 5 vertebrae.It is inserted into dorsal
aspect of vertebral border below the base of
the spine till inferior angle of scapula &
being innervated by dorsal scapular nerve.
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The last 3 Ms are known collectively as
Elevators of the scapula( one of them is
levaetor scapula)& all the 3 has a common
nerve supply( dorsal scapular nerve) and all
the 3 has a common action i.e all of them
work in elevating the scapula.
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The Deltoid M takes origin from the same areas
of the insertion of the trapezius M .Thus it arises
from the inferior aspect of the crest of spines of
scapula,acromion process& lateral third of the
clavicle.The M fibers from the 3 sites of origin
converted into a single tendon of insertion &
being inserted into the Deltoid tuberosity( on the
lateral aspect of the middle part of the
humerus).The deltoid is supplied by the Axillary
nerve& its main action is flexion of arm at
shoulder joint( anterior fibers),extension of the
arm ( posterior fibers)& abduction of the arm at
shoulder ( middle fibers) & in fact it is considered
as powerfull & main abductor M of the arm( from
18-90 degree).
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Thus if the Axillary nerve is injured or
compressed by local haematoma due to
fracture at the surgical neck of the
humerus,abduction becomes impossible
because of loss of innervation of the deltoid
M.8-90 degree).Thus if the Axillary nerve is
injured or compressed by local haematoma
due to fracture at the surgical neck of the
humerus,abduction becomes impossible
because of loss of innervation of the deltoid
M.