The Pectoral Muscles ,Serratus Anterior and Mammary gland and its applied aspect

1. The Anatomy of Pectoral Region

2. Pectoralis major
Origin
Anterior sternal half of the
clavicle;
Manubrium and Sternum upto
sixth costal cartilages
Cartilages of all the true ribs,
Aponeurosis of the abdominal
external oblique
Insertion
By a bilaminar tendon into the
lateral lip of the bicipital
groove of the humerus
Innervation
Medial and lateral pectoral
nerves

3. Actions
Flexion of the
humerus,
Adduction of the
humerus and
Medial rotation of
the humerus.
Clavicular part : flexion,
adduction, and medial
rotation of the
humerus.
Sternocostal part
extension of the flexed
arm as in climbing.
It aids in deep
inspiration.

4. Origin
It arises from the upper margins and outer
surfaces of the third, fourth, and fifth ribs,
 Inserted into the medial border and upper
surface of the coracoid process of the scapula.
Innervation
Medial and lateral pectoral nerves
Actions
Protracts the scapula with serratus anterior
Depresses the shoulder with the rhomboids
and levator scapulae
Important
The pectoralis minor muscle is covered by
the clavipectoral fascia.
The medial pectoral nerve pierces the
pectoralis minor .
Axillary artery is divided into three parts by
pectoralis minor.
Pectoralis minor

5. Clavipectoral fascia
Encloses subclavius and Pectoralis
Minor.
It is pierced by :
Lateral pectoral nerve.
Thoraco- acromial artery
Cephalic vein.
 Lymph nodes from pectoral
region to apical group of axillary
lymph nodes

6. Serratus anterior Origin
Arises from ribs 1 to 8, to be inserted into
the medial border of the scapula.
Insertion
• Medial border of the scapula between
the superior and inferior angles.
• 1st
and 2nd
digitations to upper angle of
scapula.(C5)
• 3rd
and 4th
digitations to medial border on
costal surface upto the inferior angle.
• Lower 4 digitations to inferior angle of
scapula.
Action
Protraction of the scapula along with
pectoralis minor.
• The fibres inserted on inferior angle
rotate scapula laterally and upwards in
overhead abduction with trapezius.
Assists in respiration.
Innervation
long thoracic nerve(Nerve of Bell)

7. Applied aspect
• Serratus anterior is called the
Boxer’s muscle since it is
responsible for pushing and
punching movements.
• Paralysis of this muscle results
in a "winged scapula" ,results
in protrusion of the scapula on
the affected side when the
patient is asked to push
against the wall with both
arms extended.
• Winged scapula occurs in
lateral thoracic nerve
paralysis

8. The mammary gland or
The breast
 Modified Sweat Gland
(Apocrine Type)
 Lies in Superficial fascia of
pectoral region.
BUT
A small extension known as
Axillary tail of Spence
pierces the axillary fascia
through a small foramen
called the Foramen Of
Langer and lies in the axilla.

9. EXTENT
VERTICALLY
From second to sixth rib
in midclavicular line.
HORIZONTALLY
From lateral border of
sternum to midaxillary
line along the fourth
rib.

10. Deep relations
The Base of the Mammary gland called
Mammary Bed rests upon the following
structures (from Superficial to deep)
(a)Retromammary Space
(b)Deep Fascia (Pectoral Fascia)
(c)Muscles- Pectoralis Major, Serratus Anterior,
External Oblique.
RETROMAMMARY SPACE
A Space deep to the base of the gland, lies
superficial to deep fascia, contains loose
areolar tissue, makes the gland freely
movable.

11. PRESENTING PARTS
(A)Nipple
Lies in fourth intercostal space, has high nervous
innervation and openings of 15-20 lactiferous
ducts.
(B) Areola
Pigmented area at the base of nipple, contains
modified sebaceous glands which become
enlarged during pregnancy and lactation
forming Tubercles of Montgomery

12. STRUCTURE
3 COMPONENTS
(A) FIBROUS TISSUE
(B) GLANDULAR TISSUE
(C) AREOLAR TISSUE

13. FIBROUS
TISSUE
• Forms Suspensory Ligaments of Cooper which
anchor gland to overlying skin and underlying deep
fascia.
• Divide the gland into 15-20 lobes.
• They may become contracted from fibrosis around a
carcinoma and produce a characteristic pitting of
the skin of the breast (peau d orange)

14. (B) GLANDULAR TISSUE
• Consists of 15-20 lobes.
• Arranged in a radiating
manner around the areola.
• In lobes are alveoli which
secrete milk.
• Alveoli lined by
myoepithelial cells under
oxytocin control.
• Each lobe has one lactiferous
duct.
• The lactiferous duct dilates
near its opening in the nipple
to form lactiferous sinus
which acts as reservoir of
milk.

15. Axillary Lymph
Nodes
 Anterior or Pectoral group
receive lymph from upper half
of anterior wall trunk and from
major part of breast.
 Posterior or Scapular group
receive lymph from posterior
wall of upper half of trunk and
from axillary tail of breast.
 Lateral group receives lymph
from upper limb.
 Central group receives lymph
from preceding groups and
drains into apical group.
(intercostobrachial N)
 Apical or infraclavicular
(subclavian) group lie deep to
clavipectoral fascia. They
receive lymph from the central
group, from upper part of
breast and from the thumb.

16. Lymphatic drainage of Breast
 Superficial portion of the
breast drains into the
subareolar plexus Of
Sappey.
 Deep portion of the
breast drains to the
submammary plexus.
 All the lymphatic of the
breast converge into the
Sappey plexus.

17. Lymphatic drainage of breast
 The lateral quadrants drain into
the anterior axillary or pectoral
group of lymph nodes. (75%)
 The medial quadrants drain by
internal thoracic group of nodes.
(20%)
 A few lymph vessels follow
posterior intercostals arteries
and drain into posterior
intercostals nodes. (5%)
 Some vessels communicate with
lymph vessels of opposite
breast and with lymph vessels of
anterior abdominal
wall(Subdiaphragmatic and
subperitoneal lymph plexuses)

18. ARTERIAL
SUPPLY
 Perforating branches of
the Internal thoracic
artery
Lateral mammary
branches from the
Lateral thoracic artery
Twigs from the
Intercostal arteries
 Pectoral branch of the
Thoracoacromial artery

19. Venous Supply
• Venous drainage of the breast is mainly
accomplished by the axillary vein.
• The subclavian, intercostal, and internal
thoracic veins also aid in returning blood to
the heart.
Nerve Supply
• 4th through 6th intercostal nerves

20. Applied Aspect
Mammography is a radiographic examination of the breast. This technique is
used for screening the breasts for benign and malignant tumours of the
breast.
Breast cancer occurs in upper lateral quadrant (about 60% cases) and forms a
palpable mass in later stages.
 It enlarges, attaches to Cooper’s ligaments and produces shortening of
ligaments, causing depression or dimpling of overlying skin.
 It may attach to and shorten lactiferous ducts and cause retraction of
nipple.
 Obstruction of superficial lymph vessels by cancer cells may produce
edema of skin giving rise to an orange skin appearance called Peau
d’orange appearance.
 The cancer can spread through veins to the vertebrae and brain because
the veins draining the breast communicate with the vertebral venous
plexus.

21.  Localized cancer is treated by simple mastectomy .
 Localized cancer of breast with early metastasis of axillary
lymph nodes, radical mastectomy is done to remove the
primary tumor and the lymph vessels and nodes that drain the
area. These are removed
a large area of skin overlying the tumor and including the nipple,
all the breast tissue
the pectoralis major and associated fascia,
the pectoralis minor and associated fascia
,all the fat, fascia and lymph nodes in axilla
fascia covering upper part of rectus sheath,
the serratus anterior, the subscapularis and the latissimus dorsi
muscles
 In modified radical mastectomy, the pectoral muscles are left
intact.

22. In a breast abscess an acute infection of the
mammary gland occurs in which pathogenic
bacteria gain entrance to the breast tissue
through a crack in the nipple.
 The abscess is localized to a lobe which id
drained through a radial incision to avoid
damage to the radially arranged ducts.