Pectoral Anatomy

Question 1

Mammary gland is modified _____ gland

Answer 1

sweat

Question 2

cutaneous innervation

Answer 2

the skin of the pectoral region is supplied by:

Branches of the supraclavicular nerve and The ventral rami of the intercostal nerves.

Question 3

pectoral fascia attachments

Answer 3

Superiorly: sternum and Clavicle

•Medially (midline)- Anterior part of the sternum

laterally and inferiorly: continuous with the fascia of the shoulder, axilla, and thorax.

Question 4

division of pectoral fascia

Answer 4

divides at the lateral margin of the latissimus dorsi in two layers: the anterior and posterior- they attach to the spinous processes of the thoracic vertebrae

Question 5

what is the continuation of the pectoral fascia?

Answer 5

the lower part of thoracic region: - with the the fibrous sheaths of the rectus abdominis.

interval between pectoralis major and the latissimus dorsi- it closes in the axillary space and forms the axillary fascia

Question 6

the clavipectoral fascia is a strong fascial sheet deep to the ____ head of the ______ muscle

Answer 6

clavicular head deep to the pectorals major muscle

Question 7

the clavipectoral fascia occupies the space between the _____ and ______ muscle

Answer 7

clavicle and pectorals minor muscle. It spends the floor of the axilla

Question 8

the extent of the clavipectoral fascia vertically, medially, and laterally

Answer 8

vertically- from clavicle above to the axillary fascia below.

Its upper part splits into 2 laminae to enclose the subclavius muscle

Medially, •clavipectoral fascia is connected to the first rib and costoclavicular ligament and blends with external intercostal membrane of the upper 2 intercostal spaces.

•Laterally, •it’s connected to the coracoid process and blends with the coracoclavicular ligament.

Question 9

what muscles enclosed in clavipectoral fascia

Answer 9

subclavius and pectorals minor muscle

Question 10

what structures pierce the clavipectoral fascia?

Answer 10

Outwards
-Lateral pectoral nerve and Thoraco-acromial artery.

inwards

• Lymphatics from the breast to the apical group of axillary group of lymph nodes.
• Cephalic vein

Question 11

Clavipectoral fascia

Answer 11

The posterior lamina continues with the investing layer of deep cervical fascia(fuse with the axillary sheath).

• The anterior lamina gets connected to the clavicle.
• Its lower part splits to enclose the pectoralis minor muscle.
• Below it extends downwards as the suspensory ligament of axilla,(that is connected to the dome of the axillary fascia).

The suspensory ligament keeps the dome of axillary fascia pulled up (maintaining the concavity of the axilla)

Question 12

mammary gland site

Answer 12

Is situated in the pectoral region in the superficial fascia.

A part of it called the axillary tail penetrates the deep fascia and lies in the axilla.

Question 13

mammary gland what is type of gland

Answer 13

apocrine

Question 14

extent of mammary gland

Answer 14

Vertical: •from the second rib to the sixth rib.
•Horizontal: from the lateral sternal border to the mid-axillary line. The axillary tail (of Spence) pierces into the deep fascia and extends to axilla at the level of the third rib

Question 15

shape of mammary gland

Answer 15

hemispherical in young adult females.

pendulous in the later stage of life

Question 16

support of mammary gland

Answer 16

suspensory ligaments of breast&continuous with the dermis of the skin

Question 17

arterial blood supply of mammary gland

Answer 17

Internal thoracic artery •(perforating branches)

Axillary artery
•Lateral thoracic artery
•Superior thoracic artery    
•Acromio-thoracic artery
•Subscapularis artery
•2nd to 4th intercostal arteries

Question 18

Venous drainage of mammary gland

Answer 18

Veins follow the arteries in their course and adopt their names.

Question 19

veins of mammary gland form an anastomotic venous circle around the nipple that divides into:

Answer 19

superficial anastomosis veins: drain into internal thoracic and superficial veins of the lower neck

Deep venous anastomosis: drain into internal thoracic, axillary and posterior intercostal veins

Question 20

lymphatic drainage of mammary glands via

Answer 20

mostly axillary nodes (75 %)
internal mammary (parasternal nodes) nodes

Question 21

axillary nodes group

Answer 21

Anterior (Pectoral) group: This group of lymph nodes lies on the lower border of pectoralis minor along the lateral thoracic vessels and drains outer quadrants of the breast.

• Posterior (subscapular) group: This group lies on the posterior wall of the axilla along the lower border of the subscapularis. It drains the lower outer quadrant of the breast
• Lateral group: This group of lymph nodes lies over the lateral wall of axilla besides the humerus and drains a minimal quantity of lymph from the breast.
• Central group: This group lies in the base of the axilla and receives lymph from the anterior, posterior and lateral groups of lymph nodes
• Apical groups: This group of lymph nodes lies deep in the apex of the axilla and receives lymph from all the above groups of lymph nodes. It also directly drains the upper medial quadrant of the breast.

Question 22

internal (parasternal) mammary nodes

Answer 22

Internal mammary (parasternal) nodes: •These groups of lymph nodes are beside the lateral border of the sternum surrounding the internal mammary artery and drain the medial quadrants of the breast.

•Some cross to the other side and drain to the opposite group of parasternal nodes; this is precisely the route by which metastasis from one breast (ipsilateral) spreads to the other side and becomes bilateral

Question 23

other minor nodes

Answer 23

Supraclavicular nodes•
Cephalic (deltopectoral) nodes•
Posterior intercostal nodes
•Subdiaphragmatic & subperitoneallymph plexuses: •This is the route by which the metastasis from the breast spreads to the abdomen (Yusuf et al 2019)

Note:•The skin drain into axillary, inferior deep cervical and infraclavicular nodes•The areolar and nipple drain to subareolar lymphatic plexus

Question 24

nerve supply of mammary glands come from what branches of the 2nd to 6th intercostal nerves?

Answer 24

anterior cutaneous branch and lateral cutaneous branch

Question 25

nerve supply of mammary gland come from what nerves

Answer 25

2nd to 6th intercostal nerves from the anterior cutaneous branch and lateral cutaneous branch

also from the supraclavicular nerve

Question 26

the supraclavicular nerve innervates what part of the mammary gland?

Answer 26

the upper and lateral parts

Question 27

the nipple of titty supplied by

Answer 27

4th intercostal nerve

Question 28

pectoralis major origin, insertion, nerve supply, arterial supply, action

Answer 28

origin: 3rd, 4th, and 5th ribs near their cartilage
insertion: medial aspect of coracoid process

nerve supply: medial pectoral nerve, C8 and T1

Arterial supply: pectoral branch of thoracoacromial trunk

action: depresses point of shoulder
elevates the ribs of origin when scapular is fixed

Question 29

subclavius muscle origin, insertion, nerve supply, action

Answer 29

origin: first costal cartilage
insertion: lower surface of clavicle (subclavius groove)

nerve supply: nerve to the subclavius (C5 and C6)

action: depresses the clavicle and stabilizes the clavicle during movements of the shoulder girdle

Question 30

serratus anterior origin, insertion, nerve supply, arterial supply, action

Answer 30

origin: outer surface of upper 8 ribs
insertion: costal aspect of medial margin of scapula and inferior angle of scapula

nerve supply: long thoracic nerve (C5, C6, C7)

arterial supply: lateral thoracic artery

action: draws the scapula forward around the thoracic wall (protrusion) and rotates scapula