Anatomy Tables - Pectoral Region, Posterior Shoulder & Breast

Topographical Anatomy of the Thorax

Structure/Space Description/Boundaries Significance
midaxillary line
(TG4-01)
an imaginary vertical line passing through the middle of the axilla used as a surface landmark for descriptive purposes
midclavicular line
(TG4-01)
an imaginary vertical line passing through the midshaft of the clavicle used as a surface landmark for descriptive purposes
deltopectoral triangle
(TG2-12)
a triangle in the upper chest region that is bounded medially by the clavicle, superiorly by the deltoid m., and inferiorly by the pectoralis major m. the deltopectoral triangle is pierced by the cephalic vein on its course from the upper limb to join the axillary vein in the axilla
nipple
(N182, TG2-10)
located superficial to the 4th intercostal space in the male and prepuberal female; areola is dark ring surrounding nipple location of the left nipple may be used to help locate the apex of heart, which is approximately 8 cm from the midline in the left 5th intercostal space; a surface landmark used to place the stethoscope for auscultation of the bicuspid valve
suprasternal notch(N185, TG4-04) the notch located at the superior border of the manubrium of the sternum, between the sternal ends of the clavicles also known as: jugular notch

Osteology of the Pectoral Region

Bone Structure Description Notes
clavicle
(N419, N420, TG2-03)
  an "S" shaped bone located between the sternum and the scapula it articulates medially with the manubrium of the sternum and laterally with the acromion process of the scapula; it forms a strut that supports the upper limb; it is frequently fractured; it is the first bone to begin ossification during development (Latin, clavicula = little key, this term was used to refer to the catch that fastens a window as well as to keys. Curved window fasteners resemble the shape of this bone)
rib
(N185, TG4-04)
the bone forming the lateral thoracic wall 12 pairs; several types are described: typical or "true" ribs, "false" ribs, "floating" ribs; all three types of ribs have many features in common: head, neck, tubercle, angle, body, costal groove
sternum
(N185, TG4-04)
the broad flat bone forming the anterior thoracic wall it is formed by three parts: manubrium, body, xiphoid process (Latin, sternum = breastbone, sternere = spread out)
manubrium the superior part of the sternum (Latin, manubrium = handle)
jugular (suprasternal) notch a notch on the superior border of the manubrium it is located between the clavicular notches which articulate with the sternal ends of the clavicles (Latin, jugulum = throat)
clavicular notch a notch on the superolateral border of the manubrium it articulates with the sternal end of the clavicle
sternal angle the junction of the manubrium and body of the sternum it is an anterior projection located at the level of the costal cartilage of rib 2; an important landmark for internal thoracic anatomy
body the middle part of the sternum it articulates with the manubrium superiorly and the xiphoid process inferiorly; laterally it articulates with the costal cartilages of ribs 2-7
xiphoid process the inferior part of the sternum it is variable in size, shape & ossification; it articulates with the body of the sternum superiorly (Greek, xiphos = sword + eidos = appearance)
scapula
(N420, TG2-03)
  the bone of the shoulder the scapula floats in a sea of muscles, so it is difficult to fracture; it articulates with the axial skeleton through only one bone - the clavicle at the coracoclavicular and acromioclavicular joints
coracoid process
(TG2-03)
a beak-like process that projects anteriorly from the lateral end of the superior border of the scapula it is the attachment site for the short head of the biceps brachii m., the coracobrachialis m., the pectoralis minor m. and the coracoacromial and coracoclavicular ligaments (Greek, korax = crow + eidos = appearance. The coracoid process of the scapula is shaped like a crow's beak)
humerus
(N420, TG2-03)
  the bone of the arm (brachium) the humerus articulates proximally with the scapula at the glenoid fossa; it articulates distally with the radius and ulna at the elbow joint
greater tubercle the large projection located lateral to the head of the humerus it is the attachment site of the supraspinatus, infraspinatus & teres minor mm.
intertubercular groove the groove on the anterior surface of the humerus that is located between the crest of the greater tubercle and the crest of the lesser tubercle it is occupied by the tendon of the long head of the biceps brachii m.; the transverse humeral ligament spans the intertubercular groove and holds the biceps tendon in place; it is the attachment site for the tendon of the pectoralis major (lateral lip), teres major (medial lip), and latissimus dorsi (floor) (Latin, tuber = knobby process, nodule)
crest of the greater tubercle the ridge of bone on the anterior surface of the humerus extending inferiorly from the greater tubercle it forms the lateral lip of the intertubercular groove; it is the attachment site for the transverse humeral ligament and the pectoralis major m.
crest of the lesser tubercle the ridge of bone on the anterior surface of the humerus extending inferiorly from the lesser tubercle it forms the medial lip of the intertubercular groove; it is the attachment site for the transverse humeral ligament and the teres major m.

Muscles of the Pectoral Region

Muscle Origin Insertion Action Innervation Artery Notes Image
pectoralis major
(N188, TG2-12)
medial 1/2 of the clavicle, manubrium & body of sternum, costal cartilages of ribs 2-6, sometimes from the rectus sheath of the upper abdominal wall crest of the greater tubercle of the humerus flexes and adducts the arm, medially rotates the arm medial and lateral pectoral nerves (C5-T1) pectoral branch of the thoracoacromial trunk the deep fascia on its anterior surface should not be fused to the fascia of the mammary gland - if it is, this is an important clinical sign indicating breast disease (Latin, pectus = breast bone)
pectoralis minor
(N188, N189, N428, TG2-12, TG4-07)
ribs 3-5 coracoid process of the scapula draws the scapula forward, medialward, and downward medial pectoral nerve (C8, T1) pectoral branch of the thoracoacromial trunk branches of medial pectoral nerve usually pierce pectoralis minor to reach the pectoralis major muscle (Latin, pectus = breast bone)
serratus anterior
(N188, TG4-07)
ribs 1-8 or 9 medial border of the scapula on its costal (deep) surface it draws the scapula forward; the inferior fibers rotate the scapula superiorly long thoracic nerve (from ventral rami C5-C7) lateral thoracic a. a lesion of long thoracic nerve will cause winging of the scapula (i.e., the medial border of the scapula falls away from the posterior chest wall and looks like an angel's wing) (Latin, serratus = to saw)


Arteries

Artery Source Branches Supply to Notes
thoracoacromial
(N188, N427, TG2-15, TG4-07)
axillary a., 2nd part pectoral br., clavicular br., acromial br., deltoid br. pectoralis major m., pectoralis minor m., subclavius m., deltoid m., shoulder joint thoracoacromial trunk pierces the costocoracoid membrane

Veins

Vein Tributaries Drains Into Regions Drained Notes
cephalic v.
(N424, N428, N479, TG2-02, TG2-12A, TG2-12B)
lateral side of the dorsal venous arch of the hand; superficial veins of the forearm axillary vein superficial parts of the lateral hand and lateral forearm median cubital vein usually shunts some of the blood collected by the cephalic v. to the basilic v. (Latin/Greek, kephale = head)

Lymphatics

Structure Location Afferents from Efferents to Regions drained Notes
axillary nodes
(N428, TG2-11)
axilla cubital nodes; lymphatic vessels from the upper limb, thoracic wall and subscapular region efferents vessels form the subclavian trunk, some drainage to inferior deep cervical nodes upper limb, most of the mammary gland, some of the anterolateral chest wall, posterior thoracic wall and scapular region axillary nodes number from 20 to 30 and are organized in five groups based on their position within the axilla: 1) pectoral nodes, along the lateral border of the pectoralis major m.; 2) lateral nodes, located along the distal axillary v.; 3) central nodes, centrally located along axillary v.; 4) subscapular nodes, located along the subscapular v. and its tributaries; 5) apical nodes, located at the apex of axilla
parasternal nodes
(N428, TG2-11)
lateral border of sternum, along the course of the internal thoracic vessels anterior phrenic nodes, lymphatic vessels from the anterior thoracic wall larger lymphatic vessels in the root of the neck medial side of the mammary gland; medial part of the anterior chest wall and muscles parasternal nodes constitute an important drainage pattern in cases of cancer of the mammary gland; one or two parasternal nodes may be found in the anterior end of intercostal spaces 1-6; also known as: sternal nodes
pectoral nodes
(N428, TG2-11)
along the lateral border of the pectoralis major m. along the course of the lateral thoracic vessels lymphatic vessels from the mammary gland and anterolateral thoracic wall central axillary nodes anterolateral thoracic wall and muscles; most of the mammary gland an important group of nodes to examine during a breast physical exam; also known as: anterior axillary nodes

Nerves

Nerve Source Branches Motor Sensory Notes
intercostal n.
(N180, N192, N257, TG1-17, TG4-11)
ventral primary rami of spinal nerves T1-T11 lateral & anterior cutaneous brs. intercostal muscles; abdominal wall muscles (via T7-T11); muscles of the forearm and hand (via T1) skin of the chest and abdomen anterolaterally; skin of the medial side of the upper limb (via T1-T2) intercostal n. travels below the posterior intercostal a. in the costal groove (Latin, costa = rib)
long thoracic n.
(N429,N430, TG2-13, TG2-14)
brachial plexus (ventral primary rami of spinal nerves C5-C7) no named branches serratus anterior m. no cutaneous branches located on the superficial surface of the serratus anterior m.; lesion of this nerve causes scapular winging, hence the saying "C5, 6, & 7 keep the wings from heaven"
pectoral, lateral
(N428, N429,N430, TG2-13, TG2-14, TG2-15)
lateral cord of the brachial plexus no named branches pectoralis major m. no cutaneous branches lateral pectoral n. communicates with the medial pectoral n. anterior to the axillary a.; it pierces the clavipectoral fascia
pectoral, medial
(N428, N429,N430, TG2-13, TG2-14, TG2-15)
medial cord of the brachial plexus no named branches pectoralis minor m., pectoralis major m. no cutaneous branches medial pectoral n. communicates with the lateral pectoral n. anterior to the axillary a.; it pierces the pectoralis minor m.

Viscera/Fascia

Organ/Part of Organ Location/Description Notes
clavipectoral fascia
(N188,N428, TG2-12, TG4-07)
deep fascia attaching to clavicle, surrounding subclavius m., thickened below as costocoracoid ligament, extending inferiorly to pectoralis minor as costocoracoid membrane (pierced by cephalic v., lateral pectoral n., thoracoacromial a.), encloses pectoralis minor, extends inferolaterally to attach to axillary fascia as suspensory ligament of axilla
mammary gland
(N182, TG2-10)
located anterior to pectoralis major m. from rib 2/3 to rib 6/7 the breast, a modified sweat gland, comprises glandular tissue arranged in up to 20 lobules, surrounded by subcutaneous connective tissue and supported by suspensory ligaments
lactiferous ducts
(N182, TG2-10A, TG2-10B)
drain the lobules of the mammary gland at the nipple beneath the nipple, the ducts dilate to form lactiferous sinuses
areola
(N182, TG2-10)
darkly pigmented skin surrounding the nipple

Clinical Terms

Term Definition
anomalies/variations deviation or departure from the normal or common order, form, or rule
gynecomastia excessive development of the male mammary glands, sometimes secreting milk. This can be idiopathic, or as a result of an underlying disease process. (Greek, gyn = female + mastos = breast)
axillary tail (of Spence) part of the mammary gland may extend along the inferolateral edge of the pectoralis major toward the axilla (armpit), forming an axillary tail (of Spence). This portion of breast tissue is in the upper-outer quadrant of the breast which is important because 50% of breast cancer is located in this quadrant and in the axillary tail
supernumerary nipples (polythelia) more than the normal number of nipples, may be on the breast or other parts of the body-found along the "milk line" from axilla to groin. These accessory nipples resemble raised nevi (commonly called "moles").
supernumerary breasts (polymastia) a condition in which more than two breasts are present
carcinoma any of the various types of malignant (invasive) neoplasm derived from epithelial tissue in several sites, occuring more frequently in skin, bronchi, stomach, and prostate gland in men, and in the breast, cervix, and skin in women (Greek, carcino- = cancer + -oma = tumor)
mastectomy/lumpectomy amputation of the breast or of an affected portion (Greek, mastos = breast + -ectomy = excision)
mastitis inflammation of the mammary gland (Greek, mastos = breast + -itis = inflammation)
scintigraphy record indicating the intensity, location, and distribution of radioactivity in tissue following the use of radioactive tracer substances
mammogram special imaging examination of the breast to detect breast cancer. The American Cancer Society currently recommends that screening should begin annually at the age of 40 (and earlier in those patients with a family history of breast cancer).


The material presented in these tables is contained in the book:
MedCharts Anatomy by Thomas R. Gest & Jaye Schlesinger
Published by ILOC, Inc., New York
Copyright © 1995, unauthorized use prohibited.
The excellent editorial assistance of
Dr. Pat Tank, UAMS
is gratefully acknowledged.

Updated: 21 Sep 2011