UPPER LIMB

36

3
Pectoral Region
!Who ever thought of the word “Mammogram?”. Every time I hear it, I think‘
I’m supposed to put my breast in an envelope and send it to someone’ !
—Jan Kingz

INTRODUCTION
The pectoral region lies on the front of the chest. It
essentially consists of structures which connect the
upper limb to the anterolateral chest wall. Breast lies
in this region.

Competency achievement: The student should be able to:

AN 13.6 Identify and demonstrate important bony landmarks of
upper limb: Jugular notch, sternal angle, acromial angle, spine of
the scapula, vertebral level of the medial end, inferior angle of the
scapula.1

SURFACE LANDMARKS

The following features of the pectoral region can be seen

or felt on the surface of body.
1 The clavicle lies horizontally at the root of the neck,
separating it from the front of the chest. The bone is
subcutaneous, and therefore, palpable throughout its
length. Medially, it articulates with the sternum at the
sternoclavicular joint, and laterally with the acromion Fig. 3.1: Surface landmarks: Shoulder, axilla, arm and elbow
Upper Limb

process at the acromioclavicular joint. Both the joints regions (anterior aspect)
are palpable because of the upward projecting ends
of the clavicle (Fig. 3.1). The sternoclavicular joint may 4 The epigastric fossa (pit of the stomach) is the
be masked by the sternocleidomastoid muscle. depression in the infrasternal angle. The fossa
2 The jugular notch (interclavicular or suprasternal overlies the xiphoid process, and is bounded on each
notch) lies between the medial ends of the clavicles, side by the seventh costal cartilage.
at the superior border of the manubrium sterni. 5 The nipple is markedly variable in position in
3 The sternal angle (angle of Louis) is felt as a females. In males, and in immature females, it
transverse ridge about 5 cm below the jugular notch usually lies in the fourth intercostal space just
1

(Fig. 3.1). It marks the manubriosternal joint. medial to the midclavicular line; or 10 cm from the
Section

Laterally, on either side, the second costal cartilage midsternal line. In fact, the position of the nipple is
joins the sternum at this level. The sternal angle thus variable even in males.
serves as a landmark for identification of the second 6 The midclavicular line passes vertically through the
rib. Other ribs can be identified by counting middle of clavicle, the tip of the ninth costal cartilage
downwards from the second rib. and the midinguinal point.
36
 PECTORAL REGION
37

7 The infraclavicular fossa (deltopectoral triangle) is a

triangular depression below the junction of the
lateral and middle thirds of the clavicle. It is
bounded medially by the pectoralis major, laterally
by the anterior fibres of the deltoid, and superiorly
by the clavicle.
8 The tip of the coracoid process of the scapula lies
2–3 cm below the clavicle, overlapped by the
anterior fibres of the deltoid. It can be felt on deep
palpation just lateral to the infraclavicular fossa.
9 The acromion process of the scapula (acron = summit;
omos = shoulder) is a flattened piece of bone that
lies subcutaneously forming the top of the shoulder.
The posterior end of its lateral border is called the
acromial angle, where it is continuous with the lower
lip of the crest of the spine of the scapula. The
anterior end of its medial border articulates with
the clavicle at the acromioclavicular joint.
10 The deltoid is triangular muscle with its apex directed
downwards. It forms the rounded contour of the
shoulder, extending vertically from the acromion
process to the deltoid tuberosity of the humerus.
Fig. 3.2: Points and lines of incision
11 The axilla (Latin armpit) is a pyramidal space
between the arm and chest. When the arm is raised
(abducted), the floor of the axilla rises, the anterior upward and laterally till you reach to the third point on
and posterior folds stand out, and the space becomes the areolar margin.
more prominent. The anterior axillary fold contains Encircle the areola and carry the incision upwards
the lower border of the pectoralis major, and posterior and laterally till the anterior axillary fold is reached.
axillary fold contains the tendon of the latissimus dorsi Continue the line of incision downwards along the
winding round the fleshy teres major. medial border of the upper arm till its junction of upper
The medial wall of the axilla is formed by the upper one-third and lower two-thirds. Extend this incision
4 ribs covered by the serratus anterior. The narrow transversely across the arm (refer to BDC App).
lateral wall presents the upper part of the humerus Make another incision horizontally from the xiphoid
covered by the short head of the biceps, and the process across the chest wall till the posterior axillary fold.
coracobrachialis. Axillary arterial pulsations can be Lastly, give horizontal incision from the centre of supra-
felt by pressing the artery against the humerus. The sternal notch to the lateral (acromial) end of the clavicle.
cords of the brachial plexus can also be rolled against Reflect the two flaps of skin towards the upper limb.
the humerus. The head of the humerus can be felt
by pressing the fingers upwards into the axilla.
12 The midaxillary line is a vertical line drawn midway SUPERFICIAL FASCIA
Upper Limb

between the anterior and posterior axillary folds.

The superficial fascia (Latin a band) of the pectoral
DISSECTION region is visualised after the skin has been incised. It
Mark the following points. contains moderate amount of fat, and is continuous
i. Centre of the suprasternal notch with that of surrounding regions. The breast, which is
ii. Xiphoid process
well developed in females, is the most important of all
contents of this fascia. The fibrous septa given off by
iii. 7 o’clock position at the margin of areola (left
the fascia support the lobes of the gland, and the skin
side), and 5 o’clock position at the margin of
covering the gland.
1

areola (right side)

iv. Lateral end of clavicle (Fig. 3.2). Contents
Section

Give an incision vertically down from the first point In addition to fat, the superficial fascia of the pectoral
to the second which joins the centre of the suprasternal region contains the following.
notch to the xiphoid process in the midsagittal plane. i. Cutaneous nerves derived from the cervical plexus
From the lower end of this line, extend the incision and from the intercostal nerves.
 UPPER LIMB
38

ii. Cutaneous branches from the internal thoracic and 1 The medial, intermediate and lateral supraclavicular
posterior intercostal arteries. nerves are branches of the cervical plexus (C3, C4).
iii. The platysma (Greek broad). They supply the skin over the upper half of the
iv. The breast. deltoid and from the clavicle down to the second rib.
2 The anterior and lateral cutaneous branches of the
Cutaneous Nerves of the Pectoral Region second to sixth intercostal nerves supply the skin
The cutaneous nerves of the pectoral (Latin pectus, below the level of the second rib. The inter-
chest) region are as follows (Figs 3.3 and 3.4). costobrachial nerve of T2 supplies the skin of the
floor of the axilla and the upper half of the medial
side of the arm (Fig. 3.3).
It is of interest to note that the area supplied by spinal
nerves C3 and C4 directly meets the area supplied by
spinal nerves T2 and T3. This is because of the fact that
the intervening nerves (C5–C8 and T1) have been
‘pulled away’ to supply the upper limb. It may also be
noted that normally the areas supplied by adjoining
spinal nerves overlap, but because of what has been said
above there is hardly any overlap between the areas
supplied by C3 and C4 above and T2 and T3 below
(Fig. 3.4).

Cutaneous Vessels
The cutaneous vessels are very small. The anterior
cutaneous nerves are accompanied by the perforating
branches of the internal thoracic artery. The second, third
and fourth of these branches are large in females for
supplying the breast. The lateral cutaneous nerves are
accompanied by the lateral cutaneous branches of the
posterior intercostal arteries (Fig. 3.8).
Fig. 3.3: Cutaneous nerves of the pectoral region
Platysma
The platysma (Greek broad) is a thin, broad sheet of
subcutaneous muscle. The fibres of the muscle arise
from the deep fascia covering the pectoralis major; run
upwards and medially, crossing the clavicle and the
side of the neck; and are inserted into the base of the
mandible, and into skin over the posterior and lower
part of the face. The platysma is supplied by a branch
of the facial nerve. When the angle of the mouth is pulled
Upper Limb

down, the muscle contracts and wrinkles the skin of

the neck. The platysma may protect the external jugular
vein (which underlies the muscle) from external
pressure.

Competency achievement: The student should be able to:

AN 9.2 Describe the location, extent, deep relations, structure, age
changes, blood supply, lymphatic drainage, microanatomy and
applied anatomy of breast.2
1
Section

BREAST

Fig. 3.4: Areas supplied by cutaneous nerves of the pectoral The breast is the most important structure present in
region the pectoral region.
 PECTORAL REGION
39

The breast is found in both sexes, but is rudimentary

in the male. It is well developed in the female after
puberty. It forms an important accessory organ of the
female reproductive system, and provides nutrition to
the newborn in the form of milk. Its shape may be
hemispherical, conical, pyriform, pendulous or flat.

Situation
The breast lies in the superficial fascia of the pectoral
region. It is divided into four quadrants, i.e. upper
medial, upper lateral, lower medial and lower lateral.
A small extension of the upper lateral quadrant, called
the axillary tail of Spence, passes through an opening in
the deep fascia and lies in the axilla (Fig. 3.5). The
opening is called foramen of Langer. Its base is circular.

Extent of the Base

i. Vertically, it extends from the second to the sixth Fig. 3.5: Extent of the breast
ribs.
ii. Horizontally, it extends from the lateral border of 3 The breast is separated from the pectoral fascia by
the sternum to the midaxillary line. loose areolar tissue, called the retromammary space.
Because of the presence of this loose tissue, the
Deep Relations normal breast can be moved freely over the pectoralis
The deep surface of the breast is related to the following major.
structures in that order (Fig. 3.6).
1 The breast lies on the deep fascia (pectoral fascia) Structure of the Breast
covering the pectoralis major. The structure of the breast may be conveniently studied
2 Still deeper there are the parts of three muscles, by dividing it into the skin, the parenchyma, and the
namely the pectoralis major, the serratus anterior, and stroma. The parenchyma is known as the mammary
the external oblique muscle of the abdomen. gland.

Upper Limb
1Section

Figs 3.6a and b: (a) Axillary tail and the four quadrants of breast, and (b) the muscles situated deep to the breast
 UPPER LIMB
40

Skin Stroma
It covers the gland and presents the following features. It forms the supporting framework of the gland. It is
1 A conical projection, called the nipple, is present just partly fibrous and partly fatty.
below the centre of the breast at the level of the The fibrous stroma forms septa, known as the
fourth intercostal space 10 cm from the midline. The suspensory ligaments of Cooper, which anchor the skin
nipple is pierced by 15 to 20 lactiferous ducts. It and gland to the pectoral fascia (Fig. 3.7a).
contains circular and longitudinal smooth muscle The fatty stroma forms the main bulk of the gland. It
fibres which can make the nipple stiff or flatten it, is distributed all over the breast, except beneath the
respectively. It has a few modified sweat and areola and nipple.
sebaceous glands. It is rich in nerve supply and has Blood Supply
many sensory end organs at the termination of
nerve fibres. The mammary gland is extremely vascular. It is
supplied by branches of the following arteries (Fig. 3.8).
2 The skin surrounding the base of the nipple is
1 Internal thoracic artery, a branch of the subclavian
pigmented and forms a circular area called the areola.
artery, through its perforating branches.
This region is rich in modified sebaceous glands,
2 The lateral thoracic, superior thoracic and acromio-
particularly at its outer margin. These become
thoracic (thoracoacromial) branches of the axillary
enlarged during pregnancy and lactation to form
artery.
raised tubercles of Montgomery. Oily secretions of these 3 Lateral branches of the posterior intercostal arteries.
glands lubricate the nipple and areola, and prevent The arteries converge on the breast and are distri-
them from cracking during lactation. Apart from buted from the anterior surface. The posterior surface
sebaceous glands, the areola also contains some is relatively avascular.
sweat glands, and accessory mammary glands. The The veins follow the arteries. They first converge
skin of the areola and nipple is devoid of hair, and towards the base of the nipple where they form an
there is no fat subjacent to it. Below the areola lie anastomotic venous circle, from where veins run in
lactiferous sinus where stored milk is seen. superficial and deep sets.
1 The superficial veins drain into the internal thoracic
Parenchyma (Mammary Gland) vein and into the superficial veins of the lower part
Mammary gland is a compound tubuloalveolar gland of the neck.
which secretes milk. As it lies in superficial fascia, there 2 The deep veins drain into the axillary and posterior
is no capsule. Mammary gland is a modified sweat intercostal veins.
gland. The gland consists of 15 to 20 lobes. Each lobe is
a cluster of alveoli, and is drained by a lactiferous duct. Nerve Supply
The lactiferous ducts converge towards the nipple and The breast is supplied by the anterior and lateral
open on it. Near its termination, each duct has a cutaneous branches of the 4th to 6th intercostal nerves.
dilatation called a lactiferous sinus (Figs 3.7a and b). The nerves convey sensory fibres to the skin, and
Upper Limb
1
Section

Figs 3.7a and b: (a) Suspensory ligaments of the breast and its lobes, and (b) structure of one lobe of the mammary gland
 PECTORAL REGION
41

Fig. 3.8: Arterial supply of the breast Fig. 3.9: Lymph nodes draining the breast. Radial incision is
shown to drain breast abscess
autonomic fibres to smooth muscle and to blood vessels.
The nerves do not control the secretion of milk. Lymphatic Vessels
Secretion is controlled by the hormone prolactin, 1 The superficial lymphatics drain the skin over the
secreted by the pars anterior of the hypophysis cerebri. breast except for the nipple and areola. The
The diagnosis and management of breast disease lymphatics pass radially to the surrounding lymph
should be done carefully. nodes (axillary, anterior thoracic, supraclavicular
and cephalic).
Competency achievement: The student should be able to:
2 The deep lymphatics drain the parenchyma of the breast.
AN 10.4 Describe the anatomical groups of axillary lymph nodes They also drain the nipple and areola (Fig. 3.11).
and specify their areas of drainage.3
Some further points of interest about the lymphatic
AN 10.7 Explain anatomical basis of enlarged axillary lymph nodes.4
drainage are as follows.
Lymphatic Drainage
1 About 75% of the lymph from the breast drains into
the axillary nodes; 20% into the anterior thoracic
Lymphatic drainage of the breast assumes great
importance to the surgeon because carcinoma of the
breast spreads mostly along lymphatics to the regional
lymph nodes. The subject can be described under two
heads—the lymph nodes, and the lymphatic vessels.
Lymph Nodes
Upper Limb

Groups of lymph nodes are shown in Fig. 3.9.

Lymph from the breast drains into the following
lymph nodes (Fig. 3.9).
1 The axillary lymph nodes, chiefly the anterior (or
pectoral) group. The posterior, lateral, central and
apical groups of nodes also receive lymph from
the breast either directly or indirectly.
2 The anterior thoracic (parasternal) nodes which
lie along the internal mammary (thoracic) vessels
1

(Fig. 3.10).
Section

3 Some lymph from the breast also reaches the

supraclavicular nodes, the cephalic (deltopectoral)
node, the posterior intercostal nodes (lying in front
of the heads of the ribs), the subdiaphragmatic and Fig. 3.10: The routes of lymph from the breast. The arrows show
subperitoneal lymph plexuses. the direction of lymph flow
 UPPER LIMB
42

clavipectoral fascia to reach the apical nodes, and also

to the anterior thoracic nodes (Fig. 3.12).
5 Lymphatics from the lower and inner quadrants of
the breast may communicate with the subdiaphrag-
matic and subperitoneal lymph plexuses after
crossing the costal margin and then piercing the
anterior abdominal wall through the upper part of
the linea alba.
6 Anterior and central groups of nodes are commonly
involved in carcinoma breast.
Fig. 3.11: Subareolar lymph plexus of Sappey
Competency achievement: The student should be able to:
AN 9.3 Describe development of the breast.5
nodes; and 5% into the posterior intercostal nodes.
Among the axillary nodes, the lymphatics end mostly
Development of the Breast
in the anterior group (closely related to the axillary
tail), and partly in the posterior and apical groups. 1 The breast develops from an ectodermal thickening,
Lymph from the anterior and posterior groups passes called the mammary ridge, milk line, or line of Schultz
to the central and lateral groups, and through them (Fig. 3.13). This ridge extends from the axilla to the
to the apical group. Finally, it reaches the supra- groin. It appears during the fourth week of
clavicular nodes. intrauterine life, but in human beings, it disappears
2 The anterior thoracic nodes drain the lymph not only over most of its extent persisting only in the pectoral
from the inner half of the breast, but from the outer region. The gland is ectodermal, and the stroma
half as well. mesodermal in origin.
3 A plexus of lymph vessels is present deep to the 2 The persisting part of the mammary ridge is
areola. This is the subareolar plexus of Sappey converted into a mammary pit. Secondary buds
(Fig. 3.11). Subareolar plexus and most of lymph (15–20) grow down from the floor of the pit. These
from the gland drain into the anterior or pectoral buds divide and subdivide to form the lobes of the
group of lymph nodes. gland. The entire system is first solid, but is later
4 The lymphatics from the deep surface of the gland canalised. At birth or later, the nipple is everted at
pass through the pectoralis major muscle and the the site of the original pit.
Upper Limb
1
Section

Figs 3.12a and b: (a) Deep lymphatics of the breast passing to the apical lymph nodes and the structures piercing the clavipectoral
fascia, and (b) structures piercing the clavipectoral fascia. Branches of thoracoacromial artery: a—acromial, p—pectoral, c—clavicular,
d—deltoid
 PECTORAL REGION
43

Fig. 3.14: Mammary gland—resting phase

Fig. 3.13: Milk line with possible positions of accessory nipples

Lactating Phase
3 Growth of the mammary glands, at puberty, is The gland is full of acini with minimum amount of
caused by oestrogens. Apart from oestrogens, connective tissue. Some acini are lined by tall columnar
development of secretory alveoli is stimulated by cells, others by normal columnar cells. The nucleus may
progesterone and by the prolactin hormone of the be round or oval and is seen in the middle of the cell
hypophysis cerebri. (Fig. 3.15). Droplets of fat accumulate near the free
4 Developmental anomalies of the breast are: surface of the cell. Myoepithelial cells may be seen
a. Amastia (absence of the breast), between the basement membrane and secretory cells.
b. Athelia (absence of nipple), Ducts are also seen, but they are fewer in number as
compared to the acini. The bigger ducts are lined by
c. Polymastia (supernumerary breasts),
stratified columnar or columnar epithelium.
d. Polythelia (supernumerary nipples),
e. Gynaecomastia (development of breasts in a male)
which occurs in Klinefelter’s syndrome.

Histology of Breast
The mammary glands are specialised accessory glands
of the skin, which have evolved in mammals to provide
nourishment to the young ones. Mammary gland
consists of 15–20 lobes with the same number of ducts.
Each lobe is made up of many lobules containing acini.
Upper Limb

Histologically, only lobules are discernible in the gland.

Resting Phase in Non-Pregnant Adult Female
The mammary gland in this phase consists mainly of
ducts and their branches (Fig. 3.14). The stroma has
connective tissue and fat cells.
The intralobular ducts are usually lined by low
columnar epithelium resting on a basement membrane. Fig. 3.15: Mammary gland—lactating phase
The intralobular connective tissue which is derived
1

from the papillary layer of the dermis is more cellular,

CLINICAL ANATOMY
Section

containing fibroblasts.
The interlobular connective tissue, which lies
The upper and outer quadrant of breast is a frequent
between the ducts of adjacent lobules, is derived from
site of carcinoma (cancer). The first lymph node
the reticular layer of the dermis, and is more
draining the tumour-bearing area is called ‘sentinal
fibroreticular in nature. It contains fat lobules.
 UPPER LIMB
44

node.’ Abscesses may also form in the breast and c. Retraction of nipple is a sign of cancer.
may require drainage. The following facts are worthy d. Discharge from nipple on squeezing it.
of note. e. Palpate all four quadrants with palm of hand.
• Incisions of breast are usually made radially to Note any palpable lump.
avoid cutting the lactiferous ducts (Fig. 3.9). f. Raise the arm to feel lymph nodes in axilla.
• Cancer cells may infiltrate the suspensory • Mammogram may reveal cancerous mass
ligaments. The breast then becomes fixed. (Fig. 3.19).
Contraction of the ligaments can cause retraction • Fine needle aspiration cytology is safe and quick
or puckering (folding) of the skin. method of diagnosis of lesion of breast.
• Infiltration of lactiferous ducts and their consequent
fibrosis can cause retraction of the nipple.
• Obstruction of superficial lymph vessels by cancer
cells may produce oedema of the skin giving rise
to an appearance like that of the skin of an orange
(peau d’orange appearance) (Fig. 3.16).
• Because of communications of the superficial
lymphatics of the breast across the midline, cancer
may spread from one breast to the other (Fig. 3.17).
• Because of communications of the lymph vessels
with those in the abdomen, cancer of the breast
may spread to the liver, and cancer cells may
‘drop’ into the pelvis producing secondaries there
(Fig. 3.17).
• Apart from the lymphatics, cancer may spread
through the segmental veins. In this connection,
it is important to know that the veins draining the
breast communicate with the vertebral venous
plexus of veins. Through these communications,
cancer can spread to the vertebrae and to the brain
(Fig. 3.18).
• Carcinoma usually arises from epithelium of large
ducts.
• Self-examination of breasts:
a. Inspect: Symmetry of breasts and nipples.
b. Change in colour of skin. Fig. 3.17: Lymphatic spread of breast cancer
Upper Limb
1
Section

Fig. 3.16: Peau d’orange appearance Fig. 3.18: Vertebral system of veins
 PECTORAL REGION
45

DEEP FASCIA

The deep fascia covering the pectoralis major muscle is

called the pectoral fascia. It is thin and closely attached
to the muscle by numerous septa passing between the
fasciculi of the muscle. It is attached superiorly to the
clavicle, and anteriorly to the sternum. Superolaterally, it
passes over the infraclavicular fossa and deltopectoral
groove to become continuous with the fascia covering
the deltoid. Inferolaterally, the fascia curves round the
inferolateral border of the pectoralis major to become
continuous with the axillary fascia. Inferiorly, it is
continuous with the fascia over the thorax and the rectus
sheath.

Fig. 3.19: Mammogram showing cancerous lesion Competency achievement: The student should be able to:
AN 9.1 Describe attachment, nerve supply and action of pectoralis
major and pectoralis minor.6
• Retracted nipple is a sign of tumour in the breast.
• Size of mammary gland can be increased by
putting an implant inside the gland. The size can MUSCLES OF THE PECTORAL REGION
be reduced by breast reduction surgery.
• Cancer of the mammary glands is the most Introduction
common cancer in females of all ages. It is more Muscles of the pectoral region are described in
frequently seen in postmenopausal females due Tables 3.1 and 3.2, study them on the articulated
to lack of oestrogen hormones. skeleton. Some additional features are given below.
• Self-examination of the mammary gland is the only
way for early diagnosis and appropriate treatment. Pectoralis Major
• Mastectomy is the medical term for the surgical
removal of one or both breasts, partially or Structures under Cover of Pectoralis Major
completely. A mastectomy is usually carried out a. Bones and cartilages: Sternum, costal cartilages and ribs.
to treat breast cancer. Lumpectomy is the removal b. Fascia: Clavipectoral.
of only the tumour. c. Muscles: Subclavius, pectoralis minor, serratus
• Radical mastectomy is a surgical procedure anterior, intercostals and upper parts of the biceps
involving the removal of breast, underlying brachii and coracobrachialis.
pectoral muscles and lymph nodes of the axilla as d. Vessels: Axillary.
a treatment for advanced breast cancer. e. Nerves: Cords of brachial plexus with their branches.

Table 3.1: Muscles of the pectoral region

Upper Limb

Muscle Origin Insertion

Pectoralis major • Anterior surface of medial two-thirds of clavicle It is inserted by a bilaminar tendon on the
(Fig. 3.20) • Half the breadth of anterior surface of manubrium and lateral lip of the bicipital groove in form of
sternum up to 6th costal cartilages ‘U’
• Second to sixth costal cartilages, sternal end of 6th rib The two laminae are continuous with each
• Aponeurosis of the external oblique muscle of abdomen other inferiorly
The anterior lamina is thicker and shorter
than the thinner and longer posterior lamina.
Anterior lamina receives superficial clavicular
1

and deep manubrial fibres; posterior lamina

gets costal, sternal and aponeurotic fibres
Section

Pectoralis minor • 3, 4, 5 ribs, near the costochondral junction Medial border and upper surface of the
(Fig. 3.21) • Intervening fascia covering external intercostal muscles coracoid process
Subclavius First rib at the costochondral junction Subclavian groove in the middle one-third
(Fig. 3.21) of the clavicle
 UPPER LIMB
46

Figs 3.20a and b: (a) The origin and insertion of the pectoralis major muscle, and (b) the bilaminar insertion of the pectoralis
major. The anterior lamina is formed by the clavicular and manubrial fibres; the rest of the sternocostal and aponeurotic fibres form
the base and posterior lamina. Part of the posterior lamina is twisted upside down

Table 3.2: Nerve supply and actions of muscles

Muscle Nerve supply Actions
Pectoralis major Medial and lateral pectoral nerves • Acting as a whole the muscle causes: Adduction and
(Fig. 3.20) Medial pectoral reaches it after piercing medial rotation of the shoulder joint (arm)
pectoralis minor. The lateral pectoral reaches • Clavicular part produces: Flexion of the arm
the muscle by piercing clavipectoral fascia • Sternocostal part is used in
– Extension of flexed arm against resistance
Pectoralis minor Medial and lateral pectoral nerves • Draws the scapula forward (with serratus anterior)
(Fig. 3.21) (Fig. 3.22a) • Depresses the point of the shoulder
Subclavius Nerve to subclavius from upper trunk of Steadies the clavicle during movements of the shoulder
(Fig. 3.21) brachial plexus joint. Forms a cushion for axillary vessels and divisions
of trunks of brachial plexus

Bilaminar Tendon of Pectoralis Major to get inserted the highest and form a crescentic fold
The muscle is inserted by a bilaminar tendon into the which fuses with the capsule of the shoulder joint.
lateral lip of the intertubercular sulcus of the humerus.
The anterior lamina is thicker and shorter than the
Upper Limb

posterior. It receives two strata of muscle fibres:

Superficial fibres arising from the clavicle and deep
fibres arising from the manubrium (Fig. 3.20).
The posterior lamina is thinner and longer than the
anterior lamina. It is formed by fibres from the front of
the sternum, 2nd–6th costal cartilages, sternal end of
6th rib and from the aponeurosis of the external oblique
muscle of the abdomen. Out of these, only the fibres
1

from the sternum and aponeurosis are twisted around

Section

the lower border of the rest of the muscle. The twisted

fibres form the anterior axillary fold.
These fibres pass upwards and laterally to get
inserted successively higher into the posterior lamina
of the tendon. Fibres arising lowest, find an opportunity Fig. 3.21: The pectoralis minor and subclavius muscles
 PECTORAL REGION
47

Clinical Testing
i. The clavicular head is made prominent by flexing
the arm to a right angle. The sternocostal head can
be tested by extending the flexed arm against
resistance.
ii. Sternocostal head is made prominent by abducting
arm to 60° and then touching the opposite hip.
iii. Pressing the fists against each other makes the whole
muscle prominent (Fig. 3.22b).
iv. Lifting a heavy rod makes clavicular part prominent
(right arm). Depressing a heavy rod shows
sternocostal part as prominent (left arm) (Fig. 3.22c).

Clavipectoral Fascia
Clavipectoral fascia is a fibrous sheet situated deep to
the clavicular portion of the pectoralis major muscle. It
extends from the clavicle above to the axillary fascia
below (Fig. 3.23). Its upper part splits to enclose the
subclavius muscle. The posterior lamina is fused to the
investing layer of the deep cervical fascia and to the
axillary sheath. Inferiorly, the clavipectoral fascia splits
to enclose the pectoralis minor muscle (see Fig. 4.3).
Medially, it is attached to external intercostal muscle
of upper intercostal spaces and laterally to coracoid
process. Below this muscle, it continues as the
suspensory ligament which is attached to the dome of
the axillary fascia, and helps to maintain it.
The clavipectoral fascia is pierced by the following
structures.
i. Lateral pectoral nerve (Figs 3.12a and b).
ii. Cephalic vein.

Figs 3.22b and c: Pectoralis major being tested

Upper Limb
1Section

Fig. 3.22a: Nerve supply of pectorals, subclavius and serratus

anterior Fig. 3.23: Clavipectoral fascia
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Figs 3.24a and b: (a) The serratus anterior; (b) schematic representation

iii. Thoracoacromial artery.

iv. Lymphatics passing from the breast and pectoral
region to the apical group of axillary lymph nodes
(Fig. 3.12a).

Competency achievement: The student should be able to:

AN 10.11 Describe and demonstrate attachment of serratus
anterior with its action.7

Serratus Anterior
Serratus anterior muscle is not strictly muscle of the
pectoral region, but it is convenient to consider it here.
It is also called boxer’s muscle/swimmer’s muscle.

Origin
Serratus anterior muscle arises by eight digitations from
the upper 8 ribs in the midaxillary plane and from the
fascia covering the intervening intercostal muscles. The
Upper Limb

first digitation appears in the posterior triangle of neck. Fig. 3.25: Horizontal section through the axilla showing the
It arises from the outer border of 1st rib and from a rough position of the serratus anterior
impression on the 2nd rib. Also 5th–8th digitations
interdigitate with the costal origin of external oblique The lower five digitations are inserted into a large
muscle of abdomen. triangular area over the inferior angle (Fig. 3.25).
Insertion Nerve Supply
All 8 digitations pass backwards around the chest wall. The nerve to the serratus anterior is a branch of the
1

The muscle is inserted into the costal surface of the brachial plexus. It arises from roots C5, C6 and C7 and
scapula along its medial border.
Section

is also called long thoracic nerve. The nerve enters

The first digitation is inserted from the superior angle through the apex of axilla behind 1st part of axillary
to the root of the spine. artery to reach the medial wall of axilla. It lies on the
The next two digitations are inserted lower down surface of the muscle (Figs 3.22a and 3.24a).
on the medial border. • C5 root supplies 1st and 2nd digitations.
 PECTORAL REGION
49

• C6 root supplies 3rd and 4th digitations.

• C7 root supplies 5th to 8th digitations. Mnemonics
Branches of any artery/nerve M-CAT
Actions
M—Muscular
1 Along with the pectoralis minor, the muscle pulls the
C—Cutaneous
scapula forwards around the chest wall to protract the
upper limb (in pushing and punching movements). A—Articular
2 The fibres inserted into the inferior angle of the T—Terminal
scapula pull it forwards and rotate the scapula so
that the glenoid cavity is turned upwards. In this
action, the serratus anterior is helped by the trapezius FACTS TO REMEMBER
which pulls the acromion process upwards and
backwards (see Fig. 10.6c). • Pectoralis major forms part of the bed for the
3 The muscle steadies the scapula during weight mammary gland. 75% of lymph from mammary
carrying. gland drains into axillary; 20% into anterior
4 It helps in forced inspiration. thoracic and 5% into posterior intercostal lymph
nodes.
Additional Features • The sternocostal head of pectoralis major causes
1 Paralysis of the serratus anterior produces ‘winging extension of the flexed arm against resistance.
of scapula’ in which the inferior angle and the medial • Pectoralis minor divides the axillary artery into
border of the scapula are unduly prominent. The three parts.
patient is unable to do any pushing action, nor can
he raise his arm above the head. Any attempt to do
these movements makes the inferior angle of the CLINICOANATOMICAL PROBLEM
scapula still more prominent.
2 Clinical testing: Forward pressure with the hands A 45-year-old woman complained of a firm painless
against a wall, or against resistance offered by the mass in the upper lateral quadrant of her left breast.
examiner, makes the medial border and the inferior The nipple was also raised. Axillary lymph nodes were
angle of the scapula prominent (winging of scapula), palpable and firm. It was diagnosed as cancer breast.
if the serratus anterior is paralysed (see Fig. 2.12). • Where does the lymph from upper lateral
quadrant drain?
DISSECTION • What causes the retraction of the nipple?
Identify the extensive pectoralis major muscle in the Ans: The lymph from the upper lateral quadrant
pectoral region and the prominent deltoid muscle on drains mainly into the pectoral group of axillary
the lateral aspect of the shoulder joint and upper arm. lymph nodes. The lymphatics also drain into
Demarcate the deltopectoral groove by removing the supraclavicular and infraclavicular lymph nodes.
deep fascia. Now identify the cephalic vein, a small Blockage of some lymph vessels by the cancer cells
artery and a few lymph nodes in the groove. causes oedema of skin with dimpled appearance.
Clean the fascia over the pectoralis major muscle This is called peau d’orange. When cancer cells
and look for its attachments. Divide the clavicular head
invade the suspensory ligaments, glandular tissue
of the muscle and reflect it laterally. Medial and lateral
Upper Limb

pectoral nerves will be seen supplying the muscle. or the ducts, there is retraction of the nipple.
Make a vertical incision 5 to 6 cm from the lateral border
of sternum and reflect its sternocostal head laterally.
Identify the pectoralis minor muscle under the central FURTHER READING
part of the pectoralis major. Note clavipectoral fascia • Ellis H, Colborn GL, Skandalakis JE. Surgical embryology
extending between pectoralis minor muscle and the and anatomy of the breast and its related anatomic structures.
clavicle bone (refer to BDC App). Surg Clin North Am 1993;73:611–32.
Identify the structures piercing the clavipectoral
• Streit JJ, Lenarz CJ, Shishani Y, et al. Pectoralis major tendon
fascia: These are cephalic vein, thoracoacromial artery
1

transfer for the treatment of scapular winging due to long

and lateral pectoral nerve. If some fine vessels are also
thoracic nerve palsy. J shoulder Elbow Surg 2012;21:685–90.
seen, these are the lymphatic channels.
Section

Also, identify the serratus anterior muscle showing The largest series of the direct or indirect transfer of the sternal
serrated digitations on the side of the chest wall. head of pectoralis major for insufficiency of serratus anterior in
symptomatic scapular dyskinesia.
1–7
From Medical Council of India, Competency based Undergraduate Curriculum for the Indian Medical Graduate, 2018;1:44–80.
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1. Describe mammary gland under following 3. Write short notes/enumerate:

headings: Extent, relations, blood supply, lymphatic a. Structures piercing clavipectoral fascia
drainage and clinical anatomy.
b. Winging of scapula
2. Describe pectoralis major muscle under following
c. Origin and insertion of pectoralis minor muscle
headings: Origin, insertion, nerve supply, structures
deep to it, actions and clinical anatomy. d. Root value of long thoracic nerve

1. Which of the following muscles does not form deep a. Superior thoracic
relation of the mammary gland? b. Thoracodorsal branch of subscapular artery
a. Pectoralis major c. Lateral thoracic artery
b. Pectoralis minor d. Thoracoacromial artery
c. Serratus anterior 4. Axillary sheath is derived from which fascia?
d. External oblique muscle of abdomen a. Pretracheal
2. One of the following structures does not pierce b. Prevertebral
clavipectoral fascia: c. Investing layer of cervical
a. Cephalic vein d. Pharyngobasilar
b. Thoracoacromial artery 5. Winging of scapula occurs in paralysis of:
c. Medial pectoral nerve a. Pectoralis major
d. Lateral pectoral nerve b. Pectoralis minor
3. Which of the following arteries does not supply the c. Latissimus dorsi
mammary gland? d. Serratus anterior

1. b 2. c 3. b 4. b 5. d
Upper Limb

• Name the cutaneous nerves innervating the skin of • What is peau d'orange appearance of the skin
pectoral region. overlying the breast?
• What muscles form the deep relations of the • How can cancer of one breast spread to other breast;
mammary gland? to abdomen or pelvis or spread to cranial cavity?
• What is axillary tail and what is its importance? • How does one examine the clavicular and
sternocostal heads of pectoralis major muscle?
• Where does the lymph from breast drain?
• How is the integrity of serratus anterior muscle tested?
• Name the arteries supplying the breast. • Which muscle divides the axillary artery in three
• What structures pierce the clavipectoral fascia? parts?
1
Section