The breast lies in the pectoral region and develops during puberty under the influence of female sex hormones. It is composed of lobules that radiate from the nipple. The breast undergoes changes during pregnancy and menopause. Cancer is a major health concern and can spread via the lymphatic drainage pathways. The pectoral region contains muscles that act on the arm including the pectoralis major and minor. The serratus anterior muscle rotates the scapula. All three muscles receive nerve innervation from branches of the brachial plexus. Knowledge of the anatomical structures of the breast and pectoral region is important for clinical diagnosis and management.

1. The Breast and Pectoral
region
ANA 1102: ANATOMY OF
UPPER AND LOWER LIMBS
Dr Kiryowa Haruna Muhmood

2. Lecture objectives
• To outline the structure, blood supply and
lymphatic drainage of the breast.
• To describe the embryological development
and congenital anomalies associated with
development of the breast.
• To outline the etiology, clinical presentation
and mangement of cancer of the breast.
• To outline the muscles of the pectoral region
indicating their attachments, nerve supply
and action.

3. Outline of presentation
• Introduction
• The breast: description,
developmental changes, blood
supply, lymphatic drainage,
congenital anomalies
• Muscles of the pectoral region
• Neurovascular bundles in the
pectoral region

4. Introduction
• The upper limb is the upper extremity
of the body.
• It has a great degree of mobility and is
functionally adapted to grasp, strike
and manipulate. In primates, it is also
important in locomotion
• Most of the functions of the upper
limb depend on the integrity of the
hand (especially the thumb)

5. Introduction contd…
• The upper limb is anatomically divided into
different regions namely: the pectoral region,
the shoulder, the scapular region, the axilla,
the arm, the elbow joint, the cubital fossa,
the fore arm, the wrist and the hand.
• Each region contains important anatomical
and clinical structures.
• Knowledge of these regions is important in
the diagnosis and management of lesions of
the upper limb.

7. The Pectoral region
• It contains the following structures
1) The breast
2) Pectoralis Major muscle
3) Pectoralis minor muscle
4) Serratus anterior muscle
5) Subclavius muscle
6) Neurovascular bundles

8. The Breast

9. The Breast
• The breasts are specialised accessory glands
whose function is to produce milk and sexual
arousal.
• They are normally found in the pectoral region
though abnormal breasts can be found anywhere
from the inguinal region to the axilla.
• They are present in both sexes and are normally
two in number.(left usually larger than right)
• They vary in size and shape depending on sex,
age, race and even tribe.

10. • In males and prepubertal females,
they are similar in size and shape.
• Such breasts are composed of the
nipple sorrounded by a
hyperpigmented area known as the
areolar. The breast doesn’t extend
beyond the areolar.
• Such breasts are composed of a
system of ducts embedded in
connective tissue.

12. • At puberty, the female breast enlarges and
extends from the 2nd to 6th rib, and from the
sternum to the midaxillary line.
• The breast is protuberant and is mainly
composed of fat. It is subcutaneous and lies
between skin and the muscles of the pectoral
region(breast bed).
• A small part of the breast(breast tail) extends
upwards and laterally, pierces the deep fascia
near the lower border of P. Major and enters the
axilla.

13. Retromammary space

14. • The breast is divided into 15 – 25
lobules by fibrous septa(suspensory
ligaments or coopers ligaments). The
lobules radiate out from the nipple
and their ducts open in the areolar.
• The changes at puberty are a result
of influence of female sex hormones.

16. Breast during pregnancy
•The breast greatly increases in size
due to formation of milk glands and
increased blood supply.
•The pigmentation around the areolar
increases in darkness due to
deposition of melanin. It also becomes
more extensive.
•The areolar glands become more
active.
•In late pregnancy, milk can be ejected
out of the nipples.

19. Post menopausal breast
• The breast becomes pendulous due
to loss of collagen in the suspensory
ligaments.
• The fatty tissue and glandular tissue
become atrophic and are replaced by
fibrous tissue.
• These changes are due to absence of
female sex hormones and can be
prevented by hormonal replacement
therapy during menopause.

21. Embryological development

22. • Develops as an ectodermal thickening known
as the mammary ridge during the 3rd week of
intrauterine life.
• In a 7th week embryo, the ridge extends from
the groin to the axilla on either side of the
body.
• In humans, the ridge disappears except for a
small portion in the pectoral region which
proliferates and penetrates the underlying
mesenchyme. Here it forms 16 to 24 sprouts,
which in turn give rise to small, solid buds.

23. • By the end of prenatal life, the epithelial
sprouts are canalized and form the
lactiferous ducts, and the buds form
small ducts and alveoli of the gland.
Initially, the lactiferous ducts open
into a small epithelial pit. Shortly
after birth, this pit is transformed into
the nipple by proliferation of the
underlying mesenchyme.

24. Witch's Milk in the Newborn
• While the fetus is in the uterus, the maternal
and placental hormones cross the placental
barrier and cause proliferation of the duct
epithelium and the surrounding connective
tissue.
• This may cause swelling of the mammary
glands in both sexes during the first week of
life; in some cases a milky fluid, called witch's
milk, may be expressed from the nipples. The
condition is resolved spontaneously as the
maternal hormone levels in the child fall.

25. Disorders of development
• Polythelia: presence of accessory
nipples.
• Athelia: absence of one or both
nipples.
• Polymastia: more than 2 breasts.
• Amastia: Absence of one or both
breasts.
• Inverted nipples.
• Micromastia: very small breasts.

26. Polythelia

27. Polymastia

28. Athelia

30. Polythelia

31. Blood supply of the breast

32. Arterial blood supply
• derived from thoracic branchesof
three pairs of arteries
Axillary arteries : a continuation of
subclavian artery. gives rise to external
mammary artery which in turn gives off
the lateral thoracic artery.

33. • Internal mammary (thoracic) arteries
first descending branch of
subclavian artery
supply intercostal spaces & breast
used for coronary bypass surgery
 Intercostal arteries:
numerous branches from internal &
external mammary arteries
supply intercostal spaces & breast

34. Venous drainage
• Veinous drainage follows
corresponding arteries
• Drain into lateral thoracic vein,
perforating branches of internal
thoracic vein and posterior
intercoastal veins.

35. Lymphatic drainage

36. Lymphatic drainage
• Divided into four quadrants
• Upper and lower lateral quadrants drain
into pectoral group of axillary lymphnodes
(pectoral group).
• Upper and lower medial quadrants drain
into internal thoracic nodes. Some
lymphatics from these quadrants drain into
the opposite breast.
• Lymphatic drainage important in spread of
cancer of the breast.

37. Cancer of the breast
• 3rd
commonest cancer in females(1:
ca cervix, 2: endometrial cancer)
• One of the cancers whose prevalence
has not increased with HIV.
• 1% of all cases are males.
• Has a good prognosis if diagnosed
early.

38. Aetiology
• Unknown but associated factors
include
• Early menarche
• Genetics
• Smoking
• Hormonal contraceptives
• Uninterrupted menses
• Failure to breast feed

39. Physical signs:
a. Slowly growing, painless mass
b. May demonstrate retracted nipple
c. May be bleeding from nipple
(pathognomonic)
d. May be distorted areola, or breast
contour
e. Skin dimpling in more advanced
stages with retraction of Cooper’s
ligaments

40. f. Attachment of mass
g. Edema of skin
1)with “orange skin” appearance
(peau d’orange)
2) due to blocked lymphatics
h. Enlarged axillary or deep
cervical lymph nodes

41. Common sites for
metastases
a. Lungs & pleura
b. Skeleton system (skull,
vertebral column, pelvis)
c. Liver

42. Diagnosis
• FINE NEEDLE ASPIRATION CYTOLOGY
• Biopsies
• Mammography

43. Mammography

44. Management
• Depends on stage
• May involve chemotherapy, surgery,
radiotherapy or a combination of all
those treatments.
• To be covered in surgery and
pathology

45. Mastectomy

46. Other breast disorders
• Breast mouse: fibroadenoma. Most common
benign tumor of the breast
• Fibrocystic breast changes
1) 20%+ of premenopausal women
2) discomfort, cysts
3) treatment rarely required
4) More likely to not detect a developing
cancer
• Breast cysts
• Breast abscess

47. Muscles of the pectoral
region
They include from superficial to deep
• Pectoralis major
• Pectoralis minor and subclavius
• Serratus anterior
The important notes about any muscle
in the body is its origin, Insertion,
nerve supply and action

48. Pectoralis major

49. The pectoralis major :
• This a large, fan shaped muscle, and is the most superficial
muscle in the pectoral region. It also makes up most of the
anterior wall of the axilla
• The muscle has two heads – a clavicular head (attaches to the
clavicle), and a sternocostal head (attaches to the sternum and
ribs). Fibres from both heads attach to the edge of the
intertubecular groove of the humerus.(lateral pectoral groove)
• The two heads together act to adduct and medially rotate the
humerus at the shoulder. The clavicular head also perfoms
flexion.
• The pectoralis major is innervated by the medial and lateral
pectoral nerves, which are derived from the brachial plexus

50. Clinical notes
• Absent Pectoralis Major
Occasionally, parts of the pectoralis
major muscle may be absent. The
sternocostal origin is the most
commonly missing part, and this
causes weakness in adduction and
medial rotation of the shoulder joint.

51. Pectoralis minor

52. Pectoralis minor
• The pectoralis minor muscle is much smaller than the
pectoralis major, and lies posterior (underneath) to it.
With the pectoralis major, it forms part of the anterior
wall of the axilla.
• The muscle has a triangular shape, originating from the
anterior surfaces of ribs 3 – 5. The fibres then converge
to attach to the coracoid process of the scapula.
• Contraction of the pectoralis minor depresses the
shoulder (an inferior motion), and it is innervated by the
medial pectoral nerve.

53. Clavipectoral fascia
• A thin sheet of membrane lying between the
clavicle and pectoralis minor.
• Limimited laterally by the coracoid process,
and medially being attached to the external
intercoastal membrane
• Superiorly, it splits to enclose subclavius,
and then attaches to the clavicle.
• Below subclavius, it forms the costo-coracoid
ligament that runs from the coracoid process
to the 1st costochondral junction.

54. • Inferiorly it splits to enclose
pectoralis minor muscle.
• Almost completely covered by the
pectoralis major and the deltoid
muscles.
• Pierced by the cephalic vein,
infraclavicular lymphatics, lateral
pectoral nerve and acromio thoracic
axis(clavicular, humeral, acromial
and pectoral vessels)

55. Subclavius

56. Subclavius
• A small muscle locacted below the
clavicle.
• It arises from the first coastal
cartilage and inserts on the lower
surface of the clavicle.
• Its nerve supply is nerve to
subclavius a branch of the upper
trunk of the brachial plexus.
• Action is depression of the clavicle.

57. Serratus anterior

58. Serratus anterior
• The serratus anterior is found more laterally in the chest and,
forms the medial wall of the axilla.
• The muscle consists of several strips, which originate from ribs
2-8. They attach to the costal (rib facing) surface of the medial
border of the scapula.
• The main action of the serratus anterior is to rotate the
scapula, allowing the arm to be raised over 90 degrees. It also
holds the scapula against the ribcage – this is particularly
useful when upper limb reaches anteriorly (e.g punching).
• It is innervated by the long thoracic nerve( from roots of
brachial plexus: C5, 6 and 7)

59. • Heads from 1st
and 2nd
ribs
innervated by C5
• 3rd
and 4th
ribs by C6
• 5th
, 6th
, 7th
and 8th
ribs from C7

61. Clinical Relevance: Winging of the
Scapula
• If damage to the long thoracic nerve occurs,
the serratus anterior muscle will become
paralysed. When pushing with the affected
limb, the scapula is no longer held against the
rib cage, and protrudes out of the back. It is
said to have a ‘winged’ appearance.
• The long thoracic nerve can become damaged
by trauma to the shoulder, repetitive
movements involving the shoulder or by
structures becoming inflamed and pressing on
the nerve.

63. Nerves in the pectoral
region
• Lateral pectoral nerve
• Medial pectoral nerve
• Nerve to subclaviuslong thoracic
nerve
• Branches of supraclaivular nerves

64. Lateral pectoral nerve
• Arises from lateral cord of the
brachial plexus
• Pieces clavipectoral fascia lateral to
pectoralis minor.
• Gives a separate branch to the
clavicular head

65. Medial pectoral nerve
• Arises from the medial cord of the
brachial plexus
• Pierces pectoralis minor which it
supplies
• Ends by supplying pectoralis major

66. Medial pectoral nerve

67. Nerve to subclavius
• An anterior brach of C5 and C6 from
the brachial plexus
• Enters the posterior surface of
subclavius
• Ends by supplying it.

68. Long thoracic nerve
• Arise from roots of brachial
plexus(C5, 6 and 7)
• C5 and 6 join in Scalenus medius,
emerging from its lateral border as a
single trunk
• Nerve lies in mid axillary line behind
lateral branches of intercoastal
arteries, on the surface of the muscle
deep to the fascia
• Supplies the muscle segmentally

70. Lymphatics and blood
vessels
• To be covered in the axilla

71. THE END