THORACIC WALL
MUSCLES, MAMMARY GLANDS,
CROSS-SECTION
THORACIC WALL
MUSCLES
Surface Muscles (Anterior)
Platysma
 Pectoralis major
 Pectoralis minor
 Subclavius
 Serratus anterior
 Refer in syllabus:

Table 1, pp 47-49
Figure 13, p 50
Surface Muscles (Posterior)
Latissimus dorsi
 Trapezius
 Rhomboideus major
 Rhomboideus minor
 Refer in syllabus:

Table I; pp 47-9
Deltopectoral Triangle

Boundaries:
Anterior border of the deltoid.
Superior border of the pectoralis major.
Middle third of the clavicle.
Deltopectoral Triangle

Contents:
Cephalic vein.
Deltopectoral lymph nodes.
Deltoid branch of the thoracoacromial artery.
Clavipectoral Fascia
Invests subclavius and pectoralis minor.
 Attached to clavicle and anterior thoracic
wall.
 Pierced by:

Cephalic vein
Thoracoacromial artery
Lateral pectoral nerve

Become suspensory ligament of the axilla.
THORACIC WALL
STRUCTURE
(x.s.)
Refer to Figure 15, p. 60 in
syllabus as well as background
material on pp 58-59.
MAMMARY GLAND
Mammary Glands
Modified sweat glands
 15-20 lobes
 Lobes separated by fibrous septa
 Lactiferous duct (1 per lobe)
 Lactiferous sinus (ampulla):

Dilation as duct enters nipple
Mammary Glands

Fibrous tela subcutanea:
Connective tissue layer surrounding the
entire gland.

Fatty tela subcutanea:
Adipose tissue deep to fibrous layer.

Suspensory ligament of Cooper:
Bundles of collagen fibers in dermis and
hypodermis.
Mammary Glands
Breast extends from 2nd-3rd rib superiorly
to 6th-7th costal cartilage inferiorly.
 Extends from lateral border of sternum to
beyond the anterior axillary fold.

Mammary Glands

Retromammary space:
Space between the gland and the pectoralis
major muscle.

Sinus mammarumis:
Space between the two glands.
Mammary Gland Arteries

Anterior perforating arteries:
From internal thoracic artery
To medial part of gland

Medial mammary rami:
From 2nd - 4th anterior perforating arteries
To deep medial part of gland
Mammary Gland Arteries

Lateral mammary artery:
From lateral thoracic artery.
To inferior part of gland.

Lateral mammary rami:
From lateral cutaneous branches of
intercostal arteries.
To lateral part of the gland.
Mammary Gland Veins

Superficial and deep venous plexuses
drain into internal thoracic, lateral thoracic,
and intercostal veins.
Mammary Gland Nerves

Lateral mammary nerve:
T2-T6
Anterior branch of lateral cutaneous
branch of intercostal nerves.
 Medial mammary nerve:

T2-T6

Lateral branch of anterior cutaneous
branch of intercostal nerves.
Mammary Gland Lymphatics

Perilobular and interlobular lymphatic
vessels:
Into:

Subareolar plexus:
Into:

Lateral lymphatic trunk:
From lateral and superior gland

Medial lymphatic trunk:
From medial and inferior gland
Mammary Gland Lymphatics

Lateral lymphatic trunk and Medial
lymphatic trunk:
Into:

Pectoral group of axillary lymph nodes:
Into:

Subclavian lymphatic channels
Mammary Gland Lymphatics

Accessory lymphatic drainage:
Periphery of gland drains into apical group of
axillary nodes and follows thoracoacromial
trunk.
Circumareolar channels drain into sternal
chain.
THORACIC WALL
LYMPHATICS
Lymphatic Drainage
Subareolar plexus of nodes
 Axillary lymph nodes:

Receive from:
Superficial tissues, skin, breast, extrinsic limb muscles.
Include:
Pectoral group
Lateral group
Apical group
Subscapular group
Lymphatic Drainage
Infraclavicular nodes
 Parasternal nodes
 Abdominal nodes

MECHANICS OF
RESPIRATION
Inspiration: “Bucket Handle”
Involves contraction of intercostal muscles
 Results in raising of ribs
 Results in an increase in the lateral
dimensions of the thoracic cage.

Inspiration: “Pump Handle”
Results from raising of sternum
 Results in increase in anteroposterior
dimensions of thoracic cage

Abdominal Breathing

Results from lowering of diaphragm:
Phrenic nerve

Necessary when:
Infant
Costal cartilages are calcified
Expiration

Mostly passive