The Thoracic WallThe Thoracic Wall

Surface AnatomySurface Anatomy: : Before starting your dissection, Before starting your dissection, inspect and palpate the following inspect and palpate the following surface landmarks with the cadaver surface landmarks with the cadaver in the supine position; later in the supine position; later examine the same landmarks on examine the same landmarks on

yourself.yourself. Identification of Identification of landmarks is easier on the living landmarks is easier on the living than on the preserved cadaver.than on the preserved cadaver.

1.Suprasternal Notch.1.Suprasternal Notch.2.Sternal Angle (Angle of Louis).2.Sternal Angle (Angle of Louis).3. Xiphisternal Joint.3. Xiphisternal Joint.4. Subcostal Angle.4. Subcostal Angle.5. Costal Margin.5. Costal Margin.6. Clavicle.6. Clavicle.7. Ribs.7. Ribs.8. Nipple.8. Nipple.9. Axillary Folds.9. Axillary Folds.

Dissection of Dissection of

Pectoral RegionPectoral Region

skin incisionskin incision

Make a skin incision along the full length of both clavicMake a skin incision along the full length of both clavicle. Then incise the skin in the midline from the suprasterle. Then incise the skin in the midline from the suprasternal notch to the xiphisternal junction; continue the incisinal notch to the xiphisternal junction; continue the incision along the costal margin to the midaxillary line on eacon along the costal margin to the midaxillary line on each side. h side.

Make circular incisions around the nipples.Make circular incisions around the nipples.

Reflect theReflect the skin from the midline anteriorly to the midaskin from the midline anteriorly to the mida

xillary line on each side. Leave the large skin flaps attacxillary line on each side. Leave the large skin flaps attac

hed at the midaxillary lineshed at the midaxillary lines..

Mammary GlandMammary Gland. .

The mammary gland lies in the superficial fascia cThe mammary gland lies in the superficial fascia covering the anterior chest wall. overing the anterior chest wall.

In the child and in men it isIn the child and in men it is rudimentary. In the ferudimentary. In the femal after puberty it enlarges and assumesits hemismal after puberty it enlarges and assumesits hemispherical shape. pherical shape. In the youngadult female it overlies the second to tIn the youngadult female it overlies the second to the sixth ribs and their costal cartilages and extendhe sixth ribs and their costal cartilages and extends from the lateral margin of the sternum to the mids from the lateral margin of the sternum to the mid

axillary line. Its upper lateralaxillary line. Its upper lateral edge extends round tedge extends round the lower border of the pectoralis major and enters he lower border of the pectoralis major and enters the axilla.the axilla.

In middle-aged multiparous women the breIn middle-aged multiparous women the bre

ast may be large and pendulous. In older wast may be large and pendulous. In older w

omen past the menopause the adipose tissomen past the menopause the adipose tiss

ue of the breast may become reduced in amue of the breast may become reduced in am

ount and hemispherical shape lost; theount and hemispherical shape lost; the brebre

asts then become smaller, and the overlyinasts then become smaller, and the overlyin

g skin is wrinkled.g skin is wrinkled.

Examine the mammary gland in the male and the femExamine the mammary gland in the male and the fem

ale. Noteale. Note that the nipple is surrounded by a pigmentethat the nipple is surrounded by a pigmente

d area called the areola. Incise the nipple in the female d area called the areola. Incise the nipple in the female and extend the incision into the breast. Observe that tand extend the incision into the breast. Observe that the breast tissues divided up into 15 to 20 compartmenthe breast tissues divided up into 15 to 20 compartments by fibrous septa and that the greater part of the breas by fibrous septa and that the greater part of the brea

st st substancesubstance is made up of fatty tissue. After removin is made up of fatty tissue. After removin

g theg the fat with the scalpel handle, identify one or two ofat with the scalpel handle, identify one or two o

f the lactiferous ducts and trace them to the nipple. Idf the lactiferous ducts and trace them to the nipple. Id

entify the thin sheet of muscle, the platysma, asentify the thin sheet of muscle, the platysma, as it arisit aris

es from the fascia covering the pectoralis major and pes from the fascia covering the pectoralis major and passes superiorly over the clavicle into the neck.asses superiorly over the clavicle into the neck.

Cutaneous nerves and blood vesseCutaneous nerves and blood vessels. ls. Identify the Identify the supraclavical nervessupraclavical nerves as t as they descend from the neck beneath they descend from the neck beneath the he platysmaplatysma. These supply the skin . These supply the skin of the shoulder and upper part of the of the shoulder and upper part of the thorax down to the level of the secothorax down to the level of the second costal cartilage.nd costal cartilage.

Identify the anterior and lateral cutaneous branches Identify the anterior and lateral cutaneous branches

of an intercostal nerve.of an intercostal nerve.

With the scalpel handle, firmly stroke the superficial fasWith the scalpel handle, firmly stroke the superficial fas

cia along the course of these nerves, thus removing the cia along the course of these nerves, thus removing the

overlying fat. Very often the small blood vessels that acoverlying fat. Very often the small blood vessels that ac

company the nerves are firstcompany the nerves are first identified and lead the dissidentified and lead the diss

ector to the nerves. Do not dissect out all the cutaneous ector to the nerves. Do not dissect out all the cutaneous

nerves, but spend some time tracing out a representative nerves, but spend some time tracing out a representative

sample.sample.

Pectoralis MajorPectoralis Major. .

Expose and clean the entir anterior surface of the Expose and clean the entir anterior surface of the

pectoralis major muscle. Identify the clavicular anpectoralis major muscle. Identify the clavicular an

d sternocostal origins of this muscle. Follow the td sternocostal origins of this muscle. Follow the t

endon to its insertion in the floor of the bicipital gendon to its insertion in the floor of the bicipital g

roove of the humerus. Recognize the deltopectoraroove of the humerus. Recognize the deltopectora

l triangle, an interval between the deltoid and pectl triangle, an interval between the deltoid and pect

oralis major muscles and the clavicle. Identify the oralis major muscles and the clavicle. Identify the

cephalic vein as it enters the triangle from the uppcephalic vein as it enters the triangle from the upp

er limb.er limb.

Serratus Anterior.Serratus Anterior.Expose the digitations of origin of the serratus anteExpose the digitations of origin of the serratus ante

rior from the upper eight ribs. rior from the upper eight ribs.

This important muscleThis important muscle passes round the thoracic passes round the thoracic

wall to be inserted into the medial border of the scwall to be inserted into the medial border of the sc

apula. Identify the anterior layer of the rectus sheatapula. Identify the anterior layer of the rectus sheat

h..h..

Cut the Cut the pectoralis majorpectoralis major free from its origins on the cla free from its origins on the cla

vicle, sternum, ribs, and anterior layer of the rectus shevicle, sternum, ribs, and anterior layer of the rectus she

ath. Reflect the pectoralis major laterally to expose the ath. Reflect the pectoralis major laterally to expose the

underlying underlying pectoralis minorpectoralis minor, the , the clavipectoral fasciaclavipectoral fascia, an, an

d the d the subclavius musclesubclavius muscle. Identify the lateral pectoral ner. Identify the lateral pectoral ner

ve as it pierces the clavipectoral fascia to enter the pectve as it pierces the clavipectoral fascia to enter the pect

oralis major muscle. Also identify the medial pectoral noralis major muscle. Also identify the medial pectoral n

erve as it pierces the pectoralis minor to enter the pectoerve as it pierces the pectoralis minor to enter the pecto

ralis major.ralis major.

Pectoralis MinorPectoralis Minor.. Clean the origin of the pectoralis Clean the origin of the pectoralis

minor from the third, fourth, and fifminor from the third, fourth, and fif

th ribs. Trace the fibers laterally as th ribs. Trace the fibers laterally as

they converge to be inserted into tthey converge to be inserted into t

he medial border of the coracoid phe medial border of the coracoid p

rocess.rocess.

Clavipectoral FasciaClavipectoral Fascia.. Identify this strong sheet of connective tissIdentify this strong sheet of connective tiss

ue, which is split above to enclose the subue, which is split above to enclose the sub

clavius muscle and is attatched to the claviclavius muscle and is attatched to the clavi

cle. Inferiorly, it splits to enclose the pectocle. Inferiorly, it splits to enclose the pecto

ralis minor muscle and continues downwaralis minor muscle and continues downwa

rd to join the fascial floor of the armpit.rd to join the fascial floor of the armpit.

Identify the Identify the thoracoacromialthoracoacromial vessels and vessels and cephalic cephalic

veinvein as they pierce the clavipectoral fascia. Cut the as they pierce the clavipectoral fascia. Cut the

pectoralis minor muscle free from its origin on the pectoralis minor muscle free from its origin on the

ribs and reflect it laterally. Recognize the ribs and reflect it laterally. Recognize the lateral tlateral t

horacic vesselshoracic vessels along the lateral border of the pect along the lateral border of the pect

oralis minor muscle. Do not attempt to dissect the oralis minor muscle. Do not attempt to dissect the

contents of the axilla. This area forms part of the dcontents of the axilla. This area forms part of the d

issection of the upper limb.issection of the upper limb.