The Axilla of the upper limb anatomy.pptx

The axilla, or armpit, is a pyramid-shaped space
between the upper part of the arm and the side of the
chest.
It forms an important passage for nerves, blood,and
lymph vessels as they travel from the root of the neck to
the upper limb.
The upper end of the axilla, or apex, is directed into the
root of the neck and is bounded in front by the clavicle,
behind by the upper border of the scapula, and medially
by the outer border of the first rib.

Boundriesofthe axilla
The lower end, or base
Is bounded 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),
medially 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 from above down

Medial wall:
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
The base: is formed by the skin stretching between
the anterior and posterior walls.
The axilla contains the principal vessels and nerves to
the upper limb and many lymph nodes.

Clavipectoral Fascia
The clavipectoral fascia is a strong sheet of
connective tissue that is attached above to the
clavicle.
Below, it splits to enclose the pectoralis minor
muscle and then continues downward as the
suspensory ligament of the axilla and joins the
fascial floor of the armpit.

Contents of the Axilla
The axilla contains the axillary artery and its branches,
which supply blood to the upper limb;
the axillary vein and its tributaries, which drain blood from the upper
Limb
the lymph vessels and lymph nodes, which drain lymph from the upper
limb and the breast and from the skin of the trunk, down as far as the level
of the umbilicus.
Lying among these structures in the axilla is an important nerve plexus,
the brachial plexus, which innervates the upper limb. These structures are
embedded in fat.

Axillary Artery
The axillary artery begins at the lateral border of the 1st rib as
a continuation of the subclavian and ends at the lower border
of the teres major muscle, where it continues as the brachial
artery.
Throughout its course, 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 axillary sheath.
If this sheath is traced upward into the root of the neck, it I seen
to be continuous with the prevertebral fascia.

• The pectoralis minor muscle crosses in front of the axillary artery and divides
it into three parts:
First Part of the Axillary Artery
This extends from the lateral border of the 1st rib to the upper border
of the pectoralis minor.
Relations
Anteriorly: The pectoralis major and the skin. The cephalic vein
crosses the artery.
Posteriorly: The long thoracic nerve (nerve to the serratus anterior)
Laterally: The three cords of the brachial plexus
Medially: 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
Laterally: The lateral cord of the brachial plexus
Medially: 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, it is
crossed by the medial root of the median nerve.
Posteriorly: The subscapularis, the latissimus dorsi, and the teres major. The axillary
and radial nerves also lie behind the artery
Laterally: The coracobrachialis, the biceps, and the humerus. The lateral root of the
median and the musculocutaneous nerves also lies on the lateral side.
Medially: The ulnar nerve, the axillary vein, and the medial cutaneous nerve of the
arm

Branches of the Axillary Artery
From the first part:
The highest thoracic artery is small and runs along the upper
border of the pectoralis minor.
From the second part:
The thoracoacromial artery immediately divides into terminal branches.
The lateral thoracic artery runs along the lower border of the pectoralis
minor.
From the third part:
The subscapular artery runs along the lower border of the subscapularis
muscle.
The anterior and posterior circumflex humeral arteries wind around the front
and the back of the surgical neck of the humerus, respectively .

Axillary Vein
The axillary 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 1st
rib by becoming the subclavian vein.
The vein receives tributaries, which correspond
to the branches of the axillary artery, and the
cephalic vein.

Brachial Plexus
The nerves entering the upper limb provide the following
important functions:
sensory innervation to the skin and deep structures, such as the
joints; motor innervation to the muscles;
At the root of the neck, the nerves form a complicated plexus
called the brachial plexus.
This allows the nerve fibers derived from different segments of the
spinal cord to be arranged and distributed efficiently in different nerve
trunks to the various parts of the upper limb.
The brachial plexus is formed in the posterior triangle of the neck by
the union of the anterior rami of the 5th, 6th, 7th, and 8th cervical and
the 1st thoracic spinal nerves

The plexus can be divided into: roots, trunks, divisions, and cords.
The roots of C5 and 6 unite to form the upper trunk, the root of C7 continues as the
middle trunk, and the roots of C8 and T1 unite to form the lower trunk. Each trunk
then divides into anterior and posterior divisions.
The anterior divisions of the upper and middle trunks unite to form the lateral cord,
the anterior division of the lower trunk continues as the medial cord, and the posterior
divisions of all three trunks join to form the posterior cord.
The roots, trunks, and divisions of the brachial plexus reside in the lower part of the
posterior triangle of the neck .
The cords become arranged around the axillary artery in the axilla. Here, the brachial plexus and the
axillary artery and vein are enclosed in the axillary sheath.
Cords of the Brachial Plexus All three cords of the brachial plexus lie above and lateral to the first part
of the axillary Artery . The medial cordcrosses behind the artery to reach the medial side of the

The roots, trunks, and divisions of the brachial plexus reside
in the lower part of the posterior triangle of the neck .
The cords become arranged around the axillary artery in the
axilla. Here, the brachial plexus and the axillary artery and
vein are enclosed in the axillary sheath.
Cords of the Brachial Plexus
All three cords of the brachial plexus lie above and lateral to
the first part of the axillary Artery .
The medial cordcrosses behind the artery to reach the medial side of the
second part of the artery.

The posterior cord lies behind the second part of the artery,
and the lateral cord lies on the lateral side of the second part
of the artery.
Thus, the cords of the plexus have the relationship to the
second part of the axillary artery that is indicated by their
names.
Most branches of the cords that form the main nerve trunks
of the upper limb continue this relationship to the artery in its
third part.
The branches of the different parts of the brachial plexus are
as follows:

. Branches of the Brachial Plexus Found in the Axilla
The nerve to the subclavius (C5 and 6) supplies the subclavius muscle.
It is important clinically because it may give a contribution (C5) to the phrenic
nerve; this branch, when present, is referred to as the accessory phrenic
nerve.
The long thoracic nerve (C5, 6, and 7) arises from the roots of the brachial plexus in
the neck and enters the axilla by passing down over the lateral border of the 1st rib
behind the axillary vessels and brachial plexus . It descends over the lateral surface of
the serratus anterior muscle, which it supplies.
The lateral pectoral nerve arises from the lateral cord of the brachial plexus and
supplies the pectoralis major muscle.

The musculocutaneous nerve arises from the lateral cord of the
brachial plexus, supplies the coracobrachialis muscle, and leaves
the axilla by piercing that muscle.
The lateral root of the median nerve is the direct continuation of
the lateral cord of the brachial plexus. It is joined by the medial
root to form the median nerve trunk, and this passes downward
on the lateral side of the axillary artery. The median nerve gives
off no branches in the axilla.

The medial pectoral nerve arises from the medial cord of
the brachial plexus, supplies and pierces the pectoralis minor
muscle, and supplies the pectoralis major muscle.
The medial cutaneous nerve of the arm (T1) arises from the
medial cord of the brachial plexus and is joined by the
intercostobrachial nerve (lateral cutaneous branch of the 2nd
intercostal nerve).
It supplies the skin on the medial side of the arm.
The medial cutaneous nerve of the forearm arises from the
medial cord of the brachial plexus and descends in front of the
axillary artery.

Pectoralis Minor
The pectoralis minor is a thin triangular
muscle that lies beneath the pectoralis
major.
It arises from the 3rd, 4th, and 5th ribs
and runs upward and laterally to be
inserted by its apex into the coracoid
process of the scapula.
It crosses the axillary artery and the
brachial plexus of nerves. It is used when
describing the axillary artery to divide it
into three parts

Muscles Connecting the Upper Limb to the Thoracic Wall
• Pectoralis major;
Originates from the Clavicle,
sternum, and upper six costal
cartilages
Insertion: Lateral lip of
bicipital groove of humerus
Nerve Supply: Medial and
lateral pectoral nerves from
brachial plexus
Roots: C5, 6, 7, 8; T1
Action: Adducts arm and
rotates it medially;
clavicular fibers also flex
arm

Muscles Connecting the Upper Limb to the Thoracic Wall
Serratus anterio
Originates from the Upper eight ribs
Insertion: Medial border and inferior angle of scapula
Nerve Supply: Long thoracic nerve
Roots: C5, 6, 7
Action:; rotates scapula

Subclavius:
Originates from the 1st costal cartilage
Insertion: Clavicle
Nerve Supply: Nerve to subclavius from upper trunk of
brachial plexus
Roots: C5, 6
Action:Depresses the clavicle and steadies this bone during

Muscles Connecting the Upper Limb to the Vertebral Column
Trapezius
Originates from the Occipital bone,
ligamentum nuchae, spine of 7th
cervical vertebra, spines of all
thoracic vertebrae
Insertion Upper fibers into
lateral third of clavicle; middle and
lower fibers into acromion and spine
of scapula
Nerve Supply: Spinal part of accessory
nerve (motor) and C3 and 4 (sensory)
Roots: XI cranial nerve (spinal part)
Action: Upper fibers elevate the
scapula;
middle fibers pull scapula medially;
lower fibers pull medial border of
scapula downward

The Axilla of the upper limb anatomy.pptx

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The Axilla of the upper limb anatomy.pptx