Download Dissection of the Axilla

SHOULDER REGION
MUSCLES
Coracobrachialis
Adduction
of the
shoulder &
flexion.
Pectoralis Major
The first action is
flexion of the
humerus,
Secondly, it
adducts the
humerus. Thirdly,
it rotates the
humerus
medially. Finally
it aids in deep
inspiration
Subscapularis
Internal
rotation of
the shoulder
Deltoid
Abduction
of shoulder
Infraspinatus
External
rotation
Teres Major
Adduction
of scapula
Teres Minor
The infraspinatus and
teres minor attach to head
of the humerus; as part of
the rotator cuff they help
hold the humeral head in
the glenoid cavity of the
scapula. They work in
tandem with the posterior
deltoid to externally
(laterally) rotate the
humerus, as well as
perform transverse
abduction, extension and
transverse extension.
Supraspinatus
Abduction of the shoulder
Coracobrachia
lis
Subscapularis
Pect. Major
Deltoid
Supraspinatus
Teres Major
Infraspinatus
Teres Minor
Practice





List the muscles that do
flexion of the shoulder
Coracobrachialis
Pectoralis major (upper
to part)
Anterior Deltoid
Biceps
• List the muscles that do
extension of the
shoulder
• Latissimus dorsi
• Teres major
• Posterior deltoid
• Pectoralis major (lower
fibers to neutral)
Practice





List the muscles that do
adduction of the
shoulder
Pectoralis major (lower
and upper below 90°)
Coracobrachialis
Latissimus dorsi
Teres major
List the muscles that do
abduction of the
shoulder
• Deltoid (all sections)
• Supraspinatus
• Pectoralis major (upper
past 90°)
Practice






List the muscles that do
internal rotation of the
shoulder
Subscapularis
Latissimus dorsi
Teres major
Anterior deltoid
Pect. major
• List the muscles that do
external rotation of
the shoulder
• Infraspinatus
• Teres minor
• Posterior deltoid
Questions

What muscle works closely with the anterior deltoid?
 Pectoralis major
 What muscle is involved in any lifting movements?
 Deltoid
 What is the major (strongest) extensor muscle?
 Latissimus Dorsi
 Name the four rotator cuff muscles.
 Subscapularis, Supraspinatus, Infraspinatus, and Teres minor.
 What muscle works closely with the infraspinatus?
 Teres minor
AXILLARY REGION
The axilla, or armpit, is a pyramidshaped space between the
upper part of the arm and the side of the chest.
Realize that the upper end, or apex, is directed into the root of the
neck and is bounded anteriorly by the clavicle, posteriorly by the
upper border of the scapula, and medially by the outer border of
the first rib. The lower end, or base, is bounded anteriorly by the
anterior axillary fold (formed by the lower border of the
pectoralis major muscle), behind by the posterior axillary fold
(formed by the tend of latissimus dorsi and the teres major
muscle), and medially by the chest wall.
Walls of the Axilla.
Identify the structures
forming the walls of •the
axilla:
Anterior wall.
This is formed by the pectoralis
major, pectoralis minor,
clavipectoral fascia, and
subclavius muscle
Posterior wall.
From above downward this wall is
formed by the subscapularis,
latissimus dorsi, and the teres major
muscles.
Medial wall.
This is formed by the upper four or
five ribs and the intercostal spaces
covered by the serratus anterior
muscle.
Lateral wall.
This is formed by the
coracobrachialis and biceps
muscles in the bicipital groove of
the humerus.
Axillary Sheath.
The axillary artery (but not the vein) and the
brachial plexus are enclosed in a fascial
sheath derived from the prevertebral layer of
deep cervical fascia in the neck.
Axillary Artery.
This commences at the outer border of the
first rib as a continuation of the subclavian
artery. Having passed through the axilla, it
becomes the brachial artery at the lower
border of the teres major muscle. It is
arbitrarily divided into three parts by the
pectoralis minor muscle that crosses it
anteriorly.
Brachial Plexus.
Brachial plexus



The brachial plexus is divided into Roots,
Trunks, Divisions, Cords, and Branches. There
are five "terminal" branches and numerous
other "pre-terminal" or "collateral" branches
that leave the plexus at various points along its
length.
The five roots are the five anterior rami of
the spinal nerves, after they have given off
their segmental supply to the muscles of
the neck.
These roots merge to form three trunks:
– "superior" or "upper" (C5-C6)
– "middle" (C7)
– "inferior" or "lower" (C8-T1)
Brachial plexus



Each trunk then splits in two, to form six divisions:
– anterior divisions of the upper, middle, and lower trunks
– posterior divisions of the upper, middle, and lower trunks
These six divisions will regroup to become the three cords.
The cords are named by their position with respect to
the axillary artery.
– The posterior cord is formed from the three posterior
divisions of the trunks (C5-T1)
– The lateral cord is the anterior divisions from the upper
and middle trunks (C5-C7)
– The medial cord is simply a continuation of the anterior
division of the lower trunk (C8-T1)
The branches are shown in the following diagram
THANK YOU