3.Anatomy of the Thoracic Wall

8/12/2019 3.Anatomy of the Thoracic Wall

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Anatomy of the Thoracic Wall, Axilla and Breastos Rafael Maca & **Jos Humberto Taares !uerreiro "re#nani

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The great advances achieved in the surgical treatment of breast cancer have made it

essential for mastologists to have detailed knowledge of all anatomical features ofthe breast and its syntopy with the thoracic wall and axillary region. Knowledge ofthe axillary region is particularly important, as this is the usual location for surgicalinterventions forming part of the treatment for this neoplasm that is so common.However, integrated study of these three topics is not always easy, since these aresubjects that have historically been described separately in the classical anatomytextbooks. Within this context, we had the aim of making a detailed and integratedreview of the anatomy of the breasts, the thoracic wall related to the breast and alsothe axillary region.

We started the review by studying the thoracic wall, particularly with regard to itsmuscles, vessels and nerves that are of interest to mastology. ollowing this, wedealt with the anatomy of the axilla, emphasi!ing its limits, walls and content. We

made a detailed study of the muscles that constitute its walls, together with thecorresponding innervation. We also described theplexus brachialis, with its trunks,fascicles and nerves, and correlated them with the arteries and veins that occupy theaxillary space. inally, we studied the anatomy of the breast, its topography,innervation, vasculari!ation and lymphatic drainage, and correlated the anatomicaldata with the classification of lymph node groups that is fre"uently utili!ed bymastologists.

Anatomy of the thoracic all+The skeleton of the thoracic wall is formed by thetwelve thoracic vertebra posteriorly, the sternum anteriorly and, on each side, by thetwelve ribs and the respective costal cartilage. The spaces between the ribs are filledby the intercostal musculature, which consists of three layers. Theintercostalis

externusmuscle, with fibers oriented inferoanteriorly, extends posteriorly from theplane of the costal tubercle to the plane of the costochondral articulation. rom thispoint to the sternum, the space is closed by theintercostalis externamembrane #ig.$%. &n the lower intercostal spaces, the fibers of the intercostalis externusmuscleinterfinger with those of the obliquus externusmuscle of the abdomen. Theintermediary layer is formed by the intercostalis internusmuscle, which has fibersoriented superoanteriorly. This muscle extends from the sternum to the angle of therib, posteriorly. rom there to the transverse process of the corresponding vertebra,the space is occluded by the intercostalis internamembrane. 'ore caudally, its fibersinterfinger with those of the obliquus internusmuscle of the abdomen. Theintercostalis intimusmuscle is the deepest layer of the intercostal musculature, andis the least developed of the three. &ts fibers are oriented vertically or almost parallelto those of the intercostalis internusmuscle. &t extends, anteriorly, from the plane of

the costochondral articulations to, posteriorly, the plane of the medial margin of thescapula. The neurovascular bundles, protected in the costal groove, are threadedbetween the intermediary and deep muscle layers, and are responsible for thevasculari!ation and innervation of the intercostal musculature #(ockhart et al., $)*)+Williams et al., $))+ -omrell /land, $))+ 0rake et al.. 122*%.

Thepectoralis majormuscle #igs. $ and 1%, which has a triangular shape and is veryevident on the anterior thoracic wall, has two origins3 one clavicular #medial third ofthe clavicle% and the other sternocostal #external face of the first seven costal
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cartilages, lateral margin of the sternum and upper part of the rectus abdominismuscle%. The clavicular and sternocostal fibers converge to be inserted into thelateral lip of the intertubercular groove of the humerus. The innervation is performedby thepectoralis medialisand lateralis nerves, which are branches of fasciculusmedialisand lateralisof theplexus brachialis, respectively. &t forms the anterioraxillary fold #Williams et al.+ 0rake et al.%.

Thepectoralis minormuscle #igs. $and 1% is located at a deeper level than thepectoralis major muscle, and also has a triangular shape, but of smaller dimensions.&t originates from the external face of the third, fourth and fifth ribs and is inserted inthe coracoid process of the scapula. &t is innervated also by thepectoralis lateralisand medialisnerves #Williams et al.+ 0rake et al.%.

The serratus anteriormuscle #ig. $% covers most of the lateral thoracic wall andoriginates as muscle strips from the external face of the first nine ribs. &ts fibersconverge posteriorly to be inserted into the medial margin of the scapula, thuscontributing towards forming the medial wall of the axilla. The more caudal fibersinterfinger with those of the obliquus externusmuscle of the abdomen. This muscle

stabili!es the scapula by exerting traction anteriorly and promoting elevation of theglenoid cavity. The innervation of this muscle is performed by the thoracicus longusnerve #/ell4s nerve% #Williams et al.+ 5/6, 122$+ 0rake et al.%.

The diminutive subclaviusmuscle #ig. 1%, which is posterior to the costocoracoidligament of the clavipectoral fascia and difficult to see, originates from the first rib,close to the chondrocostal junction, and its fibers run superolaterally to be inserted inthe inferior face of the middle third of the clavicle. &ts function is to stabili!e theclavicle in movements of the shoulder. &ts innervation is performed by the nerve ofthe subclaviusmuscle, a branch of the truncus superiorof theplexus brachialis#Williams et al.+ 0rake et al.%.
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The latissimus dorsi muscle #igs. 1and 7% is a wide lamina located on the dorsum ofthe trunk. &t originates from the last six vertebral spinous processes, the iliac crestand the fascia thoracolumbalis.The fibers converge to a single twisted tendon that isinserted in the intertubercular groove of the humerus. &ts innervation is performedby the thoracodorsalisnerve, a branch of the fasciculus posteriorof theplexusbrachialis#Williams et al.+ 0rake et al.%.

Theteres majormuscle #ig. 1% originates at the inferior angle of the scapula andrises parallel to the lateral scapular margin towards the medial crest of the

intertubercular groove of the humerus, where it is inserted. &t receives innervationfrom the subscapularis inferiornerve, a branch of fasciculus posteriorof theplexusbrachialis.

Together with the latissimus dorsimuscle, it forms the posterior axillary fold#Williams et al.+ 0rake et al.%.

Anatomy of the axilla+
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+ -imits+The axilla is a pyramidal space located between the upper part of thethoracic wall and the arm. &ts shape and si!e vary according to the position of thearm. Thus, it almost disappears when the arm is completely abducted. The axillaforms a passageway for the vessels and nerves from the neck to reach the upperlimb. 6natomically, the axilla is taken to have an apex, a base and four walls, threeof which formed by muscles #5nell, $)))+ 'oore 0alley, 122$%.

A.ex /or cericoaxillary mar#in01This corresponds to the threshold !onebetween the lower part of the neck and the highest part of the axilla. &ts componentsare all bones, namely3 limited medially by the first rib, posteriorly by the uppermargin of the scapula and medial face of the coracoid process of the scapula, andanteriorly by the clavicle. The arteries and nerves go through the apex from the neckto the upper limb and the veins and lymph vessels go in the opposite direction#5nell+ 'oore 0alley%.

ig. 7. Pectoralis minormuscle, clavipectoral fascia and suspensorium axillaeligament. Thepectoralis majormuscle has been extracted for better viewing#anterior view of the thorax%.

Base1This is an imaginary downward8turned surface that is wide at the thorax andnarrow at the arm and correlates with the skin and thick layer of the fascia axillarisbetween, anteriorly, the inferior margins of thepectoralis major muscle #anterioraxillary fold% and, posteriorly, the latissimus dorsi#posterior axillary fold% #ig. 1%#5nell+ 'oore 0alley%.

Anterior all1This is formed by thepectoralis majorand minormuscles. The wholepectoralis majorforms part of the wall, while only the intermediate portion of thepectoralis minorforms part of it. The space between the upper margin of thepectoralis minorand the clavicle is occupied by the clavipectoral fascia, while thespace between the lower margin of thepectoralis minormuscle and the dermis atthe axillary base is filled by the suspensory ligament of the axilla #suspensoriumaxillaeligament%. &n the more cranial portion of the clavipectoral fascia, there is athickening known as the costocoracoid ligament or Halsted4s ligament #terms notrecogni!ed by the anatomical terminology%, which extends from the first costosternalarticulation to the coracoid process of the scapula #igs. 1 and 7% #5nell+ 'oore 0alley%.


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2osterior all1This is formed by the subscapularismuscle in its upper part and theteres majorand latissimus dorsimuscles, in its lower part #ig. 1% #5nell+ 'oore 0alley%.

Medial all1This is formed by the first four ribs with their intercostalesmuscles,and also the upper part of the serratus anteriormuscle #ig. $% #5nell+ 'oore 0alley%.

-ateral all1The anterior and posterior walls converge laterally towards thehumerus, and the lateral wall is formed by the tendon of the long head #caputlongum% of the biceps brachii muscle and, more medially, the coracobrachialis muscle#ig. $% #5nell+ 'oore 0alley%.

3+ )ontents of the axilla+The contents of the axilla consist of the axillarisarteryand its branches, theaxillarisvein and its tributaries, nerves coming mostly from theplexus brachialis, and finally lymph vessels and axillareslymph nodes. &n thisproximal portion, these elements are surrounded by the axillary sheath, which is aprolongation of the pre8vertebral portion of the fascia cervicalis. /etween theseelements, there is adipose tissue and possibly mammary tissue that is craniallyprojected from the anterior face of the thorax into the axilla #Williamset al.%.


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The axillaresvessels and the branches of theplexus brachialiscross from the apex ofthe axilla towards its base, along the lateral wall and closer to the anterior wall, withthe axillarisvein anteromedial in relation to the artery. /ecause of the obli"uity ofthe upper ribs, the axillary neurovascular bundle crosses the first intercostal spacewhen it emerges from behind the clavicle #Williams et al. $))%.

3++Axillarisartery+Theaxillarisartery is a continuation of the subclaviaartery. &tstarts at the lateral margin of the first rib and finishes at the lower margin of theteres majormuscle, from which point it starts to be named the brachialisartery #ig.9%. &t is crossed anteriorly by thepectoralis minormuscle, which divides it into threeportions3 proximal, posterior and distal to the muscle. The first of these is locatedbetween the lateral margin of the first rib and the upper margin of thepectoralisminor muscle+ the second, posteriorly to the same muscle+ and the third, betweenthe lower margin of thepectoralis minormuscle and the lower margin of the teresmajormuscle #(ockhartet al.+ 5nell+ 'oore 0alley%.

ig. 9.Axillaris artery and its branches #anterior view of the left axillary region%.

The first portion of the axillarisartery originates the thoracica superiorartery+ thesecond portion originates the thoracoacromialisartery and the thoracica lateralartery+ and the third portion originates the subscapularisartery and the circunflexae
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humeri anteriorandposteriorarteries #(ockhart et al.+ Williamset al.+ 5nell+ 'oore 0alley%.

Thoracica superiorartery3 This artery projects anteromedially above the uppermargin of thepectoralis minormuscle, passing between it and thepectoralis majormuscle, and reaches as far as the thoracic wall. &t irrigates these muscles and the

thoracic wall, together with the thoracica internaartery andintercostalis supremaartery. The intercostalis supremais sometimes absent.

Thoracoacromialis artery1This is a short branch that is initially covered by thepectoralis minormuscle. &t runs along the upper margin of this muscle, penetratesthe clavipectoral fascia and divides intopectoralis, acromialis, clavicularisanddeltoideusbranches.

Thoracica lateralisartery1 This follows the lower margin of thepectoralis minormuscle as far as the thoracic wall, and irrigates thepectoralis major, serratusanteriorand subscapularis muscles and the axillareslymph nodes. &n women, thisartery is large and it has lateral mammary branches, curving around the lateral

margin of thepectoralis majormuscle and heading towards the mammary gland.

Subscapularisartery1This is the largest branch of the axillarisartery. &t is usuallyrelated to the posteroinferior margin of the subscapularismuscle. &t irrigatesadjacent muscles and the thoracic wall. &t is accompanied distally by thethoracodorsalis nerve, which innervates the latissimus dorsimuscle. 6t around fourcentimeters from its origin, it originates the circumflexa scapulaeartery, whichcurves around the lateral margin of the scapula and heads towards the infraspinalfossa, crossing the triangular space between the subscapularismuscle #above%, theteres majormuscle #below% and the long head #caput longus% of the triceps brachii#laterally%.

Circunflexa humeri anteriorartery1This is a thin artery that arises from thelateral face of the axillaris artery, distally to the lateral margin of thesubscapularismuscle. &t runs hori!ontally behind the coracobrachialismuscle and the short head#caput breve% of the biceps brachiimuscle, and anteriorly to the surgical neck of thehumerus. &t reaches the intertubercular groove of the humerus.

Circunflexa humeri posteriorartery1This artery is greater in diameter than theprevious artery. &t arises from the lateral margin of the subscapularismuscle andruns posteriorly with the axillaris nerve through the "uadrangular space delimitedabove by the subscapularismuscle, the capsule of the shoulder joint and the teresminormuscle+ below by the teres major,medially by the long head #caput longum%of thetriceps brachiimuscle and laterally by the surgical neck of the humerus.

3+3+Axillarisein+ The axillaris vein is the most anterior and medial structure inthe axillary neurovascular bundle, and is located on the medial side of the axillarisartery #5nell%. /etween these, there are thepectoralis lateralisnerve, the fasciculusmedialisof theplexus brachialisand the ulnarisand cutaneus antebrachii medialisnerves. The cutaneus brachii medialisnerve is medial to theaxillarisvein, while theaxillareslymph nodes of the lateral group are posteromedial to it. The axillarisveinhas a pair of valves close to its distal extremity. &t is formed by the union of thebrachiales veins #the comitantes veins of the brachialisartery% and the basilicavein,at the lower margin of the teres major muscle. &t ends at the lateral margin of the


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first rib, where it becomes the subclaviavein. 6lthough veins are more abundant inthe axilla than arteries, they are anatomically very variable and fre"uentlyanastomosed #Williams et al.+ 0rakeet al.%. Theaxillarisvein receives tributariesthat generally correspond to branches of the axillarisartery with a few exceptions#(ockhart et al.+ Williamset al.%.

The veins that correspond to the branches of the thoracoacromialisartery do notfuse to penetrate the axillarisvein via a common tributary. 5ome enterindependently, but other are tributaries of the cephalica vein, which is above thepectoralis majormuscle and opens into the axillarisvein close to its transition to thesubclaviavein.

Theaxillaris vein directly or indirectly receives the thoracoepigastricaeveins. Theseare formed by anastomoses of the superficial veins coming from the inguinal region,with tributaries of the axillarisvein #usually the lateral thoracicavein%, thusconstituting a collateral route that allows venous return when the cava inferiorvein isobstructed.

3+4+Axillareslym.h nodes+The soft conjunctive tissue of the axillary cavitycontains several lymph node groups. :lassically, five axillares lymph node groups aredescribed3pectorales, subscapulares, centrales, humeralesand apicales#ig. *%#(ockhart et al.+ Williams et al.+ -omrell /land+ 5/6+ 0rake et al.%.
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Pectorales#or anteriores% lymph nodes3 This is formed by three to five lymph nodesthat are located along the medial wall of the axilla, around the thoracica lateralisveinand the lower margin of thepectoralis minormuscle. This group receives lymphmainly from the anterior thoracic wall, including from the mammary gland. rom thepectoraleslymph nodes, the lymph passes to the centrales and apicales lymph nodegroups.

Subscapulares#orposteriores)lymph nodes3 This consists of six to seven lymphnodes located along the margin of the posterior axillary wall and the subscapularesvessels. These lymph nodes receive lymph from the posterior face of the thoracic

wall and the periscapular region. rom this lymph node group, lymphatic efferentfluids go out to thecentralesand apicalesnodes.

Humerales#or laterales% lymph nodes3 This is formed by a group of four to six lymphnodes located medially and posteriorly to the axillaris vein, in the proximal segmentof the vein, close to the lateral wall of the axilla. This group receives almost all thelymph coming from the upper limb, except the lymph transported by the lymphaticvessels that accompany the cephalicavein, which drains directly to the centralesnodes and, from this, to the apicaleslymph nodes.


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entraleslymph nodes3 This is formed by three or four large lymph nodes locateddeeply in relation to thepectoralis minormuscle, close to the base of the axilla, inrelation to the second portion of the axillarisartery. /ecause of its location, thisgroup receives the lymph from thepectorales, subscapularesand humerales nodes.6ll the lymph from this group drains to the apicaleslymph nodes.

Apicaleslymph nodes3 This group is also known as subclavicular lymph nodes#-omrell /land% #term not officially recogni!ed by the present anatomicalterminology ;5/6 #5/6%3 These are difficult toidentify during surgery and even in anatomical dissections, and consist of one to foursmall lymph nodes that are located between thepectoralis majorandminormuscles,in association with the pectoral branches of the thoracoacromialesvessels. Theirlymph drains directly to centraleslymph nodes, although they may more rarely drainto lymph nodes in theapicalesnodes.

"eltopectoraleslymph nodes3 These nodes are also known as infraclavicular nodes#term not recogni!ed by anatomical terminology ;5/6


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brachialis#ig. @% is formed anatomically by the primary ventral branches #ArootsA,radices% of the four inferior cervical nerves and the first thoracic nerve #:* to T$%.There may possibly be contributions from the primary ventral branches of the fourthcervical nerve and the second thoracic nerve #(ockart et al.+ Williams et al.%. 6fterthe components of the plexus emerge from the intervertebral foramens, they arepositioned between the scalenus anteriorand scalenus mediusmuscles. &n the lower

part of the neck, the primary ventral branches of theplexus brachialisjoint to formthree trunks#trunci%3 superior#:* and :@%, medius#:B% andinferior#: and T$%.

Cach trunk bifurcates into anterior and posterior divisions #divisiones% as the plexusruns posteriorly to the clavicle via the apex of the axilla. rom the mixing of thefibers from the anterior and posterior divisions of theplexus brachialis,the lateralis,medialisandposteriorfascicles are formed. The names of the fascicles refer to theirrelationships with the second portion of the axillarisartery, i.e. they are respectivelylateral, medial and posterior in relation to the second portion of the axillarisartery

#5nell+ 'oore 0alley%.

&n accordance with the relationship with the clavicle, theplexus brachialisis, forteaching purposes, divided into the supraclavicular and infraclavicular portions.

&n the axilla, the following nerves are found #(ockhart et al.+ Williams et al.+ -omrell /land+ 5/6+ 0rake et al.%.
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!ntercostobrachialisnerve3 This corresponds to the lateral cutaneous branch of thesecond intercostalisnerve. &t arises from the second intercostal space and runsobli"uely towards the arm, where it anastomoses with the cutaneous brachii medialisnerve, which is a branch of theplexus brachialis.6 second intercostobrachialis nervemay also occasionally be observed emerging from the third intercostal space.

#horacicus longusnerve #/ell4s nerve%3 This originates from the posterior face of theprimary ventral branches of :*, :@ and :B. &t runs downwards and goes posteriorlyto the neurovascular bundle, towards the lateral thoracic wall to innervate theserratus anteriormuscle. &t is covered by fascia of this muscle.

Subclavius nerve #a branch of the upper trunk of theplexus brachialis%3 The fibers ofthis nerve derive mainly from :* nerve, with contributions from :9 and :@ nerves. &truns downwards to the clavicle and supplies the subclaviusmuscle.

Pectoralis lateralisnerve #a branch of thefasciculus lateralisof theplexus brachialis%3This supplies thepectoralis major muscle, after penetrating the clavipectoral fasciatogether with thethoracoacromialisartery and cephalica vein #it does not penetrate

the pectoralis minor muscle%. &t sends out a communicating branch to thepectoralismedialisnerve, which innervates thepectoralis minormuscle.

$usculocutaneusnerve #a branch of the fasciculus lateralisof theplexus brachialis%3Dpon leaving the axilla, this nerve penetrates the coracobrachialismuscle andinnervates it. Dpon leaving this, it runs between the biceps brachiiand brachialismuscles and supplies them. &t continues superficially and laterally as a cutaneusantebrachiilateralis nerve in the forearm.

$edianusnerve3 This is formed by the lateral and medial roots coming from thefasciculus lateralisand fasciculus medialis,respectively. &t innervates most of theflexors and pronators muscles of the forearm and five intrinsic muscles of the hand,and it picks up the sensitivity of the skin of part of the hand and fingers.

Pectoralis medialisnerve #a branch of the fasciculus medialisof theplexusbrachialis%3 This nerve penetrates thepectoralis minormuscle to supply it, andcontinues to also innervate thepectoralis majormuscle.

utaneus brachii medialis nerve #a branch of the fasciculus medialisof theplexusbrachialis%3 This is a thin nerve that picks up the sensitivity of the medial face of thearm and the superior medial face of the forearm.

utaneus antebrachii medialisnerve #a branch of the fasciculus medialisof theplexus brachialis%3 This nerve is bigger than the preceding one and is locatedbetween the axillaris artery and vein, supplying the skin of the medial face of theforearm.

%lnaris nerve #a branch of thefasciculus medialisof theplexus brachialis%3 This runsthe whole length of the arm without innervating anything. &n the forearm itinnervates two flexors muscles and in the hand it is the principal nerve, since itinnervates the majority of its intrinsic muscles.


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#horacodorsalisnerve #a branch of the fasciculus posteriorof theplexus brachialis%3This innervates the latissimus dorsimuscle. &t accompanies the subscapularis andthoracodorsalisarteries anteriorly to thesubscapularismuscle.

Subscapularis superiorisnerve #a branch of the fasciculus posteriorof theplexusbrachialis%3 This is located medially to the thoracodorsalisneurovascular bundle and

innervates the subscapularis muscle.

Subscapularis inferioris nerve #a branch of the fasciculus posteriorof theplexusbrachialis%3 This innervates the teres majormuscle and the lower part of thesubscapularismuscle. &t is located laterally to the thoracodorsalisneurovascularbundle.

Axillarisnerve #a branch of thefasciculus posteriorof theplexus brachialis%3 Thissupplies the teres minormuscle as it leaves the axillary space through the"uadrangular space. &t innervates the deltoideusmuscle from its deep posterior partand continues as a cutaneus brachii lateralis superiorisnerve, innervating the skin onthe lower half of the deltoideusmuscle.

&adialisnerve #a branch of the fasciculus posteriorof theplexus brachialis%3 This isthe biggest nerve in theplexus brachialis. 6fter leaving the axilla, it penetrates thegroove of theradialis nerve of the humerus, where it may be damaged in the eventof humeral fractures. &t innervates all the extensors muscles of the posteriorcompartments of the arm and forearm, and also the supinatorand brachioradialismuscles. &t originates thecutaneus brachiiand antebrachii posterioresnerves, andalso thecutaneous brachii lateralis inferior nerve.

&njuries to nerves may occur during axillary lymphonodectomy. /y respecting theaxillaris vein as the most cranial limit of the field of lymph node dissection, thefascicles and different branches of theplexus brachialiswill be protected frominadvertent lesion. Eonetheless, some nerves may suffer injury duringlymphonodectomy. The intercostobrachialis nerve is fre"uently sectioned because itcrosses the axilla obli"uely towards the arm and is located within the product fromthe lymph node dissection. /ecause this is a sensitive nerve, the impairment causedwill consist of hyposthesia of the skin that covers the axilla and medial face of thearm. The thoracicus longus nerve runs laterally along the thoracic wall and is usuallydetached from its bed when the fascia of the serratus anteriormuscle is removed,such that the nerve adheres to the dissection product. &f this situation is not noticed,it may result in sectioning of the nerve and conse"uent denervation of the serratusanterior muscle, which causes posterior displacement of the scapula #AwingedscapulaA% #-omrell /land%. The thoracodorsalisnerve may suffer injury if thesubscapularesvessels are damaged or ligated. The subscapulares superiorandinferiornerves become damaged when the fascia of thesubscapularismuscle is

extracted and the field of dissection extends posteriorly to the axillaris vein, or overthe latissimus dorsimuscle superolaterally #subscapularis inferior nerve%. (igation ofthe thoracoacromialisartery beyond its emergence from the clavipectoral fascia willcause sectioning of thepectoralis lateralis nerve. &njury to thepectoralis medialisnerve occurs when thepectoralis minormuscle is extracted, or when the spacebetween the pectoral muscles is extensively dissected.

Anatomy of the breasts+


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+ Anatomical descri.tion+The breasts have a conical shape and are located, oneon each side, within the subcutaneous layer of the thoracic wall, anteriorly to thepectoralis majormuscle. They extend superiorly as far as the level of the second rib,inferiorly as far as the level of the sixth or seventh ribs, laterally as far as theanterior axillary line #sometimes as far as the middle axillary line% and medially theyreach the lateral margin of the sternum. Fosteriorly, they make contact with the

fascia of thepectoralis major, serratus anterior and obliquus externusmuscles andthe most cranial portion of the rectus abdominismuscle #Eetter, $))@+ -omrell /land%.

&ts base is circular and measures around $2 to $1 cm, but its volume is veryvariable. The weight of a non8lactating breast ranges from $*2 to 11*g, while alactating breast may exceed *22g in weight. The breasts of nulliparous women havea hemispherical shape, while those of multiparous women are broader andpendulant. With aging, the breast volume decreases and the breast becomes lessfirm, flatter and pendulant #-omrell /land%.

Three portions are distinguished anatomically3 the gland itself #glandula mammaria%,

the mammary papilla #papilla mammariae% and the areola #areola mammae%. Themammary gland is formed by fifteen to twenty lobes # lobi glandulae mammariae%that are arranged radially and delimited by septa of conjunctive tissue and adiposetissue in the subcutaneous layer #ig. B%. The mammary parenchyma is moreabundant in the upper half of the gland, especially in the superolateral "uadrant. Themammary tissue fre"uently extends beyond the apparent outline of the breast,projecting towards the axilla as an axillary process #sometimes called tail of 5pence;5/6


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The subcutaneous layer #tela subcutanea% completely surrounds the gland, except inthe region of the papilla #Williams et al.+ Eetter%. &t needs to be clarified that thesubcutaneous layer was in the past named the superficial fascia #Hollinshead -osse, $))$%. The part of this layer located immediately in front of the fascia of thepectoralismajor muscle was erroneously called the deep layer of the superficialfascia #-omrell /land%. &n the subcutaneous layer, fascicles of conjunctive tissueare observed to permeate the lobes and lobules, particularly in the upper part of thegland, which cross the breast anteroposteriorly, extending from the dermis to thepart of the subcutaneous layer next to the fascia of thepectoralis major muscle.These fascicles are known as the suspensory #or :ooper4s ;5/6


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presents a distal saclike dilatation known as the lactiferous sinus 'sinus lactiferi%#Williams et al.+ Eetter+ -omrell /land% #ig. B%. &t is worth emphasi!ing that,although the term nipple is habitually utili!ed in clinical practice #Eetter%, it isrecommended that the expression mammary papilla should be utili!ed in theanatomical terminology #5/6%.

The areola is a slightly raised disc8shaped area of variable si!e surrounding thepapilla. &nitially, it has a rosy hue, but becomes irreversibly pigmented #chestnutbrown% from the second month of gestation. ?n its surface, it presents granular andpointlike elevations known as areolar tubercles #tubercula areolares% or'ontgomery4s tubercles #Eetter+ -omrell /land%. These correspond to theanatomical representation of glands with intermediate histological structure betweensudoriparous and mammary glands, the areolar glands #glandulae areolares%#awcett, $))9%.

3+ 6asculari7ation+The mammary irrigation is done by means of medial and lateralmammary branches of vessels #rami mammarii medialesandlaterales% #-omrell /land% #ig. %. The mammarii medialesbranches originate from penetrating

branches of thethoracica internaartery #a branch of the subclaviaartery%, whichemerges from the second, third and fourth intercostal spaces #Williams et al.%. &n thepast, this artery was named the internal mammary artery #(ockhart et al.+Hollinshead -osse%, but this name should no longer be used. The mammariilateralesbranches have multiple origins, namely3 $%thoracica superiorartery #abranch of the first portion of the axillarisartery%+ 1% thoracica lateralartery #a branchof the second portion of the axillaris artery%+ 7%pectoralesbranches of thethoracoacromialisartery #a branch of the second portion of the axillarisartery%+ 9%penetrating branches of the intercostales posterioresarteries of the second, third andfourth spaces. Themammarii laterales branches predominantly originate from thethoracica lateralartery #formerly called the external mammary artery% #Williams etal.+ Hollinshead -osse%.
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The venous drainage from the mammary gland is done by veins that generallyaccompany the arteries. 'edially, the veins drain to the thoracica internavein #atributary of the brachiocephalicavein%, and laterally to the axillaris vein. 0rainage isalso done by the intercostales posterioresveins. Those of the second and third

intercostal spaces drain to theintercostalis supremavein, which in the right side is atributary of the arch of the a!ygos vein and on the left side, of the leftbrachiocephalica vein. Those of the fourth space drain to thea(ygos vein #on theright side% and hemia(ygosvein #on the left side% #(ockhart et al.+ Williams et al.+-omrell /land+ 0rake et al.%. The superficial #cutaneous% mammary veins arepresented profusely anastomosed and easily visible during gestation, the Haller4svascular network #Eetter%. 6round the mammary papilla, the veins form ananastomotic venous plexus of circular shape, known as the venous circle #Eetter%, aterm that is not applied in the anatomical terminology #5/6%.

4+ -ym.hatic draina#e. our intercommunicating lymphatic plexuses in the breastare described3 one located in the dermis #cutaneous plexus%, one in the superficialsubcutaneous region #subcutaneous plexus%, one in the fascia of thepectoralis major

muscle #fascial plexus% and the last in the mammary gland, involving the lobes andducts #glandular plexus%. This last one communicates by means of lymphatic vesselsthat accompany the lactiferous ducts with a region of the subcutaneous plexuslocated immediately below the areola that is known as the subareolar plexus #or5appey4s plexus%. The fascial plexus establishes communication with thesubcutaneous plexus by means of the lymphatic vessels along the fibrous fascicles ofthe stroma #Williams et al.+ -omrell /land%.


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The deep and superficial #cutaneous% lymphatic drainage is performed by the lateraland medial efferent lymphatic vessels, to lymph nodes respectively in the axilla andalong the thoracicae internaevessels #ig. *%. The medial efferent vessels of onebreast may anastomose with those of the contralateral breast, thus establishingintermammary lymphatic anastomoses #intermammary communication%. Thisexplains the occasional metastatic involvement of contralateral axillareslymph nodes

in relation to neoplasm in the other breast #-omrell /land+ Eetter%. The lateralefferent lymphatic vessels initially lead to thepectoraleslymph nodes that arelocated along the thoracicae internaevessels, close to the lower margin of thepectoralis majorand minormuscles, and sometimes directly to the lymph nodesalong the subscapulares vessels #subscapulareslymph nodes%. The lymph vesselsmay occasionally accompany the intercostales posterioresvessels and lead to theintercostaleslymph nodes, which are located close to the heads of the ribs, fromwhere the drainage is to the ductus thoracicus#(ockhart et al.+ Williams et al.+-omrell /land%.

The fascial lymphatic plexus does not have significant participation in the drainage ofthe breast, but serves as an alternative route in the event of obstruction of theprincipal route. The lymph of the fascial plexus drains to efferent vessels thatpenetrate thepectoralis majorand minor muscles and, from there, drain to theapicalesnodes of the axilla #-omrell /land%. ?n this transpectoral drainage route,also known as Gros!man4s route #Eetter%, an intermediate group of lymph nodes isdescribed #between one and four in total%, arranged along the thoracoacromialesvessels and situated between thepectoralis major and minormuscles. These lymphnodes are known asinterpectoraleslymph nodes =or -otter4s lymph nodes #5/6%>and are rarely brought into view during surgery or in anatomical specimens #ig. *%.

6lthough there is a belief that the lymph nodes along the thoracicae internaevesselsreceive the lymph from the medial "uadrants, studies have shown that both theaxillareslymph nodes and the thoracicae internaelymph nodes receive lymph fromall the mammary "uadrants, thanks to the widespread lymphatic network. There is,

however, clear predominance of drainage to the axilla, and this route corresponds tomore than three "uarters of the mammary lymphatic drainage. The most cranial partof the breast may have lymphatic drainage directly towards the apicaleslymph nodesof the axilla #-omrell /land%.

The lymph from the breasts may occasionally drain via lymphatic vessels thataccompany the lateral cutaneous branches of theintercostalesvessels and drain tothe intercostales posteriores lymph nodes, which are located close to the heads ofthe ribs. rom there, the lymph continues to the ductus thoracicus.The lymphaticvessels from the breasts may also occasionally drain to the liver andsubdiaphragmatic plexus, by means of the abdominal lymphatic vessels #Gerota4sparamammary route% #Eetter+ -omrell /land%.

5+ $nneration. The sensitivity of the breast is picked up by means of medial,lateraland superior mammariibranches of nerves #ig. )%. The medial branchescorrespond to the anterior cutaneous branch of theintercostales nerves of thesecond to sixth spaces. The lateral branches correspond to the communicatingbranch and the anterior division of the lateral cutaneous branch of the same nerves.The only exception is the lateral cutaneous branch of the second intercostalisnerve,named the intercostobrachialis nerve, which runs to the base of the axilla and thesuperior medial face of the arm. The superior branches run to the most cranial region


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of the breasts and correspond to the supraclaviculares mediales, intermediiandlateralesnerves #branches of theplexus cervicalis%. The mammary papilla isplentifully supplied by free and branched nerve ends #(ockhart et al.+ Williams et al.+-omrell /land+ 0rake et al.%.

5ympathetic fibers reach the breast by means of the abovementioned nerves forvasomotor control, but not for secretion activities, which are controlled by hormonalmechanisms. There are no fibers of parasympathetic nature in the breasts #awcett%.

R8"8R8%)89

0rake, -. (.+ ogl, W. 'itchell, 6. W. ray*s Anatomia cl+nica para estudantes.-iode Ianeiro, Clsevier, 122*.

awcett, 0. W.A textboo of Histology.Eew Jork, :hapman Hall, $))9.

Hollinshead, W. H. -osse, :.Anatomia.9aed. -io de Ianeiro, &nterlivros, $))$.

(ockhart, -. 0.+ Hamilton, G. . yfe, . W.Anatomy of the human body.(ondon,aber and aber (imited, $)*).


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'oore, K. (. 0alley, 6. .Anatomia orientada para a cl+nica. 9aed. -io de Ianeiro,Guanabara8Koogan, 122$.

Eetter, . H. #he iba collection of medical illustrations. A compilation of painting son the normal and pathologic anatomy of the reproductive system.$2thed. EewIersey3 :iba8Geigy :orporation+ $))@.

-omrell, (. I. /land, K. &.Anatomy of the breast, axilla, chest -all, and relatedmetastatic sites. !n3 /land K&, :opeland C', editors. The breast comprehensivemanagement of benign and malignant disease. 1nd ed. Fhiladelphia, W/ 5aunders:ompany, $)).

5/6 #5ociedade /rasileira de 6natomia%. #erminologia Anatmica. #erminologiaAnatmica !nternacional.$ ediLo. 5Lo Faulo, 'anole, 122$.

5nell, -. 5.Anatomia cl+nica para estudantes de $edicina.*aed. -io de Ianeiro,Guanabara8Koogan, $))).

Williams, F. (.+ Warwick, -.+ 0yson, '. /annister, (. H. ray/s anatomy. 7Bthed.(ondon, :hurchill (ivingstone, $)).

Work developed in the 0epartment of 'orphology of the 5chool of 'edical 5ciencesof 5anta :asa de 5Lo Faulo, /rasil.

orrespondence to0 "r. 1os2 &afael $ac2a"epartamento de $orfologia, 3aculdade de i4ncias $2dicas da Santa asa de S5oPaulo&ua es6rio $ota 17nior, 89, :ila ;uarque,

>9?=>=.S5o Paulo SP, ;&AS!@

==8, Accepted0 99?9=?>==8

Breast Anatomy

What is the difference between superficial and deep arteries and veins?

Where does the breast lie anatomically?

What are the main anatomical features of the breast?

What changes occur in the breast during puberty?

What changes occur in the breast during pregnancy?

What changes occur in the breast post-lactation?
http://www.scielo.cl/[email protected]%20http://www.scielo.cl/[email protected]%20http://www.scielo.cl/scielo.php?pid=S0717-95022006000500030&script=sci_arttext#tophttp://www.scielo.cl/[email protected]%20http://www.scielo.cl/[email protected]%20


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What changes occur in the breast following menopause?

What changes occur in the breast during the menstrual cycle?

Lymphatics

How does lymph from lymph vessels eventually re-enter the circulation?

Do lymphatic vessels contain smooth muscle?

Where does lymph produced in the breast drain to?

What are the 5 main groups of axillary lymph nodes?

Breast Anatomy

What is the difference between superficial and deep arteries and veins?

Superficial fascia lies just deep to sin and is a fibre meshwor that is interspersed withfat! "his fat is called subcutaneous fat! #ust underneath this layer is the deep fascia which

is another meshwor membrane which tightly covers muscle and bone! $n anatomy

structures that lie superficial to the deep fascia are deemed superficial where as those thatlie deep to it are the deep veins% arteries etc!

Where does the breast lie anatomically?

"he breast lies within the superficial fascia and over ribs &-'! $t is a roughly circular

pendulous sac which overlies the pectoralis major muscle and stretches from the sternumto the mid-axillary line!

What are the main anatomical features of the breast?

-(entral )ipple* (omposed of dense connective tissue% circular smooth muscle and has

no hair or sweat glands!

-+reola* Surface tissue surrounding the nipple containing sebaceous glands! $t doesn,thave sweat glands!


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-+xillary "ail* +n extension that continues to the axilla

-"he breast is composed of lobules of glandular tissue that are surrounded by a

connective tissue sheath! "hese are located deep within fat and are anchored to the sinby suspensory ligaments (ooper,s ligaments.!

What changes occur in the breast during puberty?

-"he lactiferous ducts branch and proliferate to form lobules

-/at is deposited

-)ipples and +reola enlarge

What changes occur in the breast during pregnancy?-"here is further duct and lobule proliferation

-"here is an increased number of secretory alveoli

-"he sebaceous glands enlarge

-0ermanent increase in the pigmentation of the areola

What changes occur in the breast post-lactation?

-+trophy of lobules and ducts

-/atty replacement of breast tissue

What changes occur in the breast following menopause?

-+trophy of lobules and ducts

-/atty replacement of breast tissue

-1educed collagenous connective tissue


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What changes occur in the breast during the menstrual cycle?

-"here is increased blood flow and increased fluid retention mid cycle!

Lymphatics

2ymphatics in 3eneral

2ymph contain debris% protein etc!

45 of blood that returns to the heart is drained by the venous system!

65 leaves circulation and enters interstitial spaces that is drained by the lymphaticsystem!

How does lymph from lymph vessels eventually re-enter the circulation?

"he lymph vessels feed into lymph nodes where immune cells 7 cells% " cells and

macrophages. which chec between self and non-self in the lymph system! "he lymphatic

system is organised as a serious of plexuses! 8ach plexus is meshwor of lymphaticvessels surrounding an organ% sin etc from which leaves an afferent lymph vessel which

drains to a lymph node! 9sually a lymph vessel will accompany an artery or vein! "his isbecause the pulsation of the vessel provides enough energy to also move the lymph bac

to the heart! 2ymph ultimately drains to larger truns and finally to the thoracic ductwhere it enters the circulation!

Do lymphatic vessels contain smooth muscle?

2ymph vessels do not contain smooth muscle and have one way valves that means allmovement through the lymphatic system is passive! +s an exception some large

lymphatic truns do contain muscle : the thoracic duct and right lymphatic duct drains

upper right ;uadrant of the body. are the most important of these!

Where does lymph produced in the breast drain to?


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3.Anatomy of the Thoracic Wall

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Transcript of 3.Anatomy of the Thoracic Wall