Pectoral Anatomy Flashcards
Mammary gland is modified _____ gland
sweat
cutaneous innervation
the skin of the pectoral region is supplied by:
Branches of the supraclavicular nerve and The ventral rami of the intercostal nerves.
pectoral fascia attachments
Superiorly: sternum and Clavicle
•Medially (midline)- Anterior part of the sternum
laterally and inferiorly: continuous with the fascia of the shoulder, axilla, and thorax.
division of pectoral fascia
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
what is the continuation of the pectoral fascia?
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
the clavipectoral fascia is a strong fascial sheet deep to the ____ head of the ______ muscle
clavicular head deep to the pectorals major muscle
the clavipectoral fascia occupies the space between the _____ and ______ muscle
clavicle and pectorals minor muscle. It spends the floor of the axilla
the extent of the clavipectoral fascia vertically, medially, and laterally
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.
what muscles enclosed in clavipectoral fascia
subclavius and pectorals minor muscle
what structures pierce the clavipectoral fascia?
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
Clavipectoral fascia
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)
mammary gland site
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.
mammary gland what is type of gland
apocrine
extent of mammary gland
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
shape of mammary gland
hemispherical in young adult females.
pendulous in the later stage of life
support of mammary gland
suspensory ligaments of breast&continuous with the dermis of the skin
arterial blood supply of mammary gland
Internal thoracic artery •(perforating branches)
Axillary artery •Lateral thoracic artery •Superior thoracic artery •Acromio-thoracic artery •Subscapularis artery •2nd to 4th intercostal arteries
Venous drainage of mammary gland
Veins follow the arteries in their course and adopt their names.
veins of mammary gland form an anastomotic venous circle around the nipple that divides into:
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
lymphatic drainage of mammary glands via
mostly axillary nodes (75 %) internal mammary (parasternal nodes) nodes
axillary nodes group
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.
internal (parasternal) mammary nodes
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
other minor nodes
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
nerve supply of mammary glands come from what branches of the 2nd to 6th intercostal nerves?
anterior cutaneous branch and lateral cutaneous branch
nerve supply of mammary gland come from what nerves
2nd to 6th intercostal nerves from the anterior cutaneous branch and lateral cutaneous branch
also from the supraclavicular nerve
the supraclavicular nerve innervates what part of the mammary gland?
the upper and lateral parts
the nipple of titty supplied by
4th intercostal nerve
pectoralis major origin, insertion, nerve supply, arterial supply, action
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
subclavius muscle origin, insertion, nerve supply, action
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
serratus anterior origin, insertion, nerve supply, arterial supply, action
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
