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Anatomy Tables - Pectoral Region & Breast
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Anatomy Tables - Pectoral Region & Breast |
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Topographical Anatomy of the Thorax |
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|---|---|---|
| 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 |
| cubital fossa (N418, TG2-24) |
superior - line between humeral epicondyles, medial - pronator teres, lateral - brachioradialis | site for phlebotomy |
Osteology of the Pectoral Region |
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|---|---|---|---|
| Bone | Structure | Description | Notes |
| clavicle (N419, N420, N421, TG2-03A, TG2-03B, Practical) |
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) | |
| acromial extremity | the flattened lateral end of the clavicle | it is marked on its inferior surface at the junction of the medial 2/3 and the lateral 1/3 by a roughened area for attachment of the coracoclavicular ligament; it articulates with the coracoid process of the scapula through a syndesmosis; it articulates with the acromion process of the scapula through a synovial joint; due to the shape of the distal clavicle, the acromion process passes inferior to the clavicle in acromioclavicular dislocations (Latin, akron = tip + omos = shoulder, therefore the tip of the shoulder) | |
| 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 |
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|---|---|---|---|---|---|---|---|
| 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 |
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|---|---|---|---|---|
| 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 |
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|---|---|---|---|---|
| Vein | Tributaries | Drains Into | Regions Drained | Notes |
| cephalic v. (N424, N428, N479, TG2-02, TG2-12A, TG2-12B, Practical) |
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) |
| basilic (N479, N480, TG2-02, Practical) |
dorsal veins of hand medially; superficial veins of forearm, median cubital vein | unites with brachial vein(s) to form the axillary vein | superficial parts of medial hand & medial forearm | connects with deep veins of the forearm via perforating veins |
| median cubital (N479, TG2-02, Practical1, Practical2) |
cephalic | basilic | superficial parts of hand & forearm | a median antebrachial vein is possible and, when present, it may drain into the median cubital vein |
| dorsal venous network of hand (N480, TG2-02, Practical) |
dorsal metacarpal veins | medially into basilic v. and laterally into cephalic v. | superficial, dorsal aspect of digits | unlike the foot, a distinct arch may be absent in the hand, replaced by a dorsal venous network of veins |
Lymphatics |
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|---|---|---|---|---|---|
| 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 |
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|---|---|---|---|---|---|
| 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. |
| antebrachial cutaneous, lateral (N429, N430, N431, N477, N479, N480, TG2-02, TG2-15, TG2-17, TG2-50) |
musculocutaneous n. | anterior and posterior branches | none | skin of the lateral side of the forearm | lateral antebrachial cutaneous n. emerges from the lateral intermuscular interval between biceps and brachialis; it is the continuation of the musculocutaneous n. (Latin, cutis = skin) |
| antebrachial cutaneous, medial (N429, N430, N431, N477, N479, N480, TG2-02, TG2-15, TG2-17, TG2-50, Practical) |
medial cord of the brachial plexus | no named branches | none | skin of the medial side of the forearm | medial antebrachial cutaneous nerve travels with the basilic vein for part of its course (Latin, cutis = skin) |
| antebrachial cutaneous, posterior N429, N430, N431, N477, N479, N480, TG2-02, TG2-15, TG2-17, TG2-50) | radial n. | inferior lateral brachial cutaneous n. | none | skin of the lateral distal arm and posterior forearm | posterior antebrachial cutaneous n. passes posterior to the lateral epicondyle of the humerus (Latin, cutis = skin) |
| superficial radial n. (N478, TG2-50, Practical) |
radial n. | dorsal digital brs. | sympathetic motor for the skin | skin of the posterolateral wrist and hand; dorsum of the lateral 2 1/2 digits (excluding the skin over the distal phalanx/nail bed) | superficial radial n. is located deep to the brachioradialis muscle |
| dorsal branch of the ulnar n. (N476,N480, TG2-14, TG2-49, Practical1, Practical2) |
ulnar n. | dorsal digital | sympathetic motor innervation to skin | skin of the dorsal surface of the medial 2 1/2 digits; skin of the medial side of the back of the hand | dorsal branch of the ulnar n. emerges at the level of the ulnar styloid process (Latin, ulna = elbow) |
Viscera/Fascia |
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|---|---|---|
| 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 | |
| brachial fascia (N479, TG2-02) |
sheath of deep fascia enclosing the arm that is continuous superiorly with the pectoral and axillary layers of fascia | attached inferiorly to the epicondyles of the humerus and the olecranon of the ulna and is continuous with the antebrachial fascia |
| antebrachial fascia (N480, TG2-02) |
anterior and posterior thickening forming the extensor retinaculum; immediately distal but deeper to the palmar carpal ligament it forms the flexor retinaculum | formation of the carpal tunnel through which the median n. and flexor tendons pass |
| 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. |
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