5 Axilla and arm anatomy - trebloc

Axilla contents

1) Axillary vessels: axilla transmits the NVB to the arm with axillary vein medial to artery & nerves 2) Infraclavicular BPx 3) Lateral brs of some intercostal nerves 4) Lymph tissue 5) Fat ± breast axillary tail

Scapula and prox arm attachments

17 total Include nerve supply -serratus -subscapularis: upper & lower subscapular N -triceps -bicepsx2 -coracobrachialis -omohyoid: ansa cervicalis -deltoid -trapezius -pec minor -infraspinatus: suprascap N -supraspinatua: suprascap n -rhomboid major: dorsal scapula n -rhomboid minor: as above -lat dorsi -levator scap: dorsal scapula n -tm: axillary N -TM: lower subscapular N

Nerve lesions - MN supracondylar - MN wrist - UN elbow - UN wrist

First row is meant to say high MN ie before AIN is given off. -Supracondylar fractures can cause neurapraxia type injuries to most commonly AIN, then radial nerve palsy, and third is ulnar nerve palsy, seen w flexion-type injury patterns -Nearly all cases resolve spontaneously, and therefore, further diagnostic studies are not indicated in the acute setting

Axillary & arm nodes -how many nodes total? -what groups are there?

-35-50 LNs in SLAP CIA Senseless -ADx levels: I - lat to pm; II - beneath pm; III - medial to pm -Supratrochlear: lie above med epicondyle & drains ulnar forearm/hand -Lateral: lies on medial side axillary vein (level II) -Ant/pectoral: on ant part of medial axilla wall, at lower border pm (level I), drains ant upper trunk & breast -Posterior/subscapularis: on post part of medial axilla wall, drains upper half of post trunk & axillary tail of breast -Central: lies in axillary fat & receives lymph from above groups -Infraclavicular: lies along cephalic vein in DP groove; drains skin of shoulder, lower neck, breast into apical LNs -Apical: Lies in axilla apex, receives from above & drains into via Subclavian lymph trunk into supraclav nodes in lower post triangle, then into Tx duct or R lymphatic trunk

Axilla boundaries

-Ant: PM, pm, subclavius, w CPF covering part between upper border of pm & clavicle -Post: STD from above down with subscapularis, TM, then Dorsi tendon winding around the TM muscle -Medial: upper 4 ribs & intercostal spaces covered by upper part of serratus anterior -Lateral: intertubercular groove of the humerus -Apex: cervicoaxillary canal ie clavicle, scapula, outer border of 1st rib -Floor: skin, fat, axillary fascia extending from the anterior to posterior axillary folds & from the fascia over the serratus anterior to deep fascia of the arm. The suspensory ligament from lower border of pec minor is attached to fascial floor from above.

Brachial artery -course -branches

-Continuation of AA is superficial between biceps & triceps; crossed by MN lat to med at midpoint humerus, with UN always posterior -5 branches PSI RU 1) PBA: enters arm via lower tri space w RN, runs between long & MH on spiral groove then divides into RCA & MCA 2) SUCA: runs w UN, pierces MIMS to enter post compartment, travels between ME & olecranon, then deep to FCU to join PUR & IUC 3) IUCA: arises 5cm before elbow crease, runs ant to ME, joins AUR anteriorly & post gives branches to SUC/PUR 4) RA 5) UA

Deltoid

-From Lat third of clavicle, acromion, spine of scapula as far medial as the 'deltoid tubercle' -To middle of lat surface of humerus (deltoid tuberosity) -Abducts arm (main muscle, working w supraspinatus); ant fibres assist PM w flexion & MR; post fibres assist LD w extension & LR -Axillary N (C5,6) (from post cord). AN runs behind surgical neck of humerus, entering muscle radially, so splitting it vertical wont damage them. AN surface anatomy is transverse line 5cm below acromion, ∴ IM injections <4cm below acromion -Deltoid flap is fasciocutaneous flap from post deltoid subcutaneous artery, a septocutaneous br of PCHA from axillary, that emerges between post deltoid & triceps, to supply skin over post half deltoid

Axillary artery -borders -how many parts -invested by -list the branches

-From continuation of subclavian artery at lat border of 1st rib, to inf border of TM to become brachial artery -Divided by pec minor (like an axe) into 3 parts, with 1st part having 1, 2nd part 2, 3rd part 3 branches. -Invested by the axillary sheath, projected down from the prevertebral fascia. -Branches are STL,SAP 1) Sup thoracic 2) thoracoacromial axis 3) lat thoracic 4) subscapular (circumflex scapula & TDA) 5) ant circumflex humeral 6) post circumflex humeral

Intermuscular septum of arms

-MIMS extends along medial supracondylar line: gives origin to brachialis & med head triceps, pierced by UN & ulnar collateral artery -LIMS extends along lat supracondylar line; gives origin to BR & ECRL & med head triceps; pierced by RN & PBA (ant desc br)

Triceps

-Type II muscle from PBA branches, entering deep part of upper 1/3 of muscle as it runs between long & lateral heads -Arises by 3 heads: long head via infraglenoid tubercle, then runs down between other 2 heads & joins with them; lat head via upper half post humerus; med head via lower half post humerus below spiral groove & both IMS -To post olecranon process of ulna -Extends elbow. LH stabilises abducted GHJ -RN (c6-8) via 4 brs from all above spiral groove: order is long, med, lat, med (Medial = More) -Can be pedicled ant or post to cover superior lat trunk & axilla; segmental transposition (ie one head) preserves muscle function

UL embryology

-W4 to W8 -made of core of mesoderm from somatic lateral plate, covered by ectoderm -growth occurs in 3 axes by 3 signalling centres which interact by releasing specific morphogens (ZAD is SFW)

BPX lesions -whole -upper -lower

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Other flaps -Lateral thoracic flap -Radial recurrent flap -Ulnar recurrent flap

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Short scapular muscles diagram

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Axillary and upper arm fascia 1) Pectoral fascia 2) Clavipectoral fascia 3) What pierces CPF

1) Pectoral fascia -Thin deep fascia that covers anterior PM -Attaches to sternum, clavicle, & continues laterally with axillary fascia. -Forms floor of retromammary space 2) CPF -Strong fascial sheet deep to PM -Upper part, aka costocoracoid membrane, runs from coracoid process (lat) to external intercostal membrane of upper two spaces (med) -Encloses subclavius above, then fuses into band, the costocoracoid ligament, stretching from the knuckle of the coracoid to the first costochondral junction -Below pm the fascia, aka suspensory lig of axilla, extends downwards & attaches to axillary fascial floor. 3) Piercing CPF •CLIT: 2 passing in, 2 passing out -Cephalic vein (IN) -LPN (OUT) -Infraclavicular LN lymphatics, going to apical LN (IN) -Thoracoacromial artery branches x4 (OUT)

Pectoralis minor

1) Type 3 muscle (as per M&N book) -D1: pectoral branch of TAA - enters deep surface of muscle close to its insertion & runs along its anterior border -D2: branch of lateral thoracic artery - enters deep surface of muscle close to insertion & runs along posterior border 2) Technique -Incision along anterior axillary line -Retract PM to see pm -Lat Tx vessels are seen lateral to PM over SAM -Trace LT to deep surface of pm -Divide pm origin at coracoid process -Retract pm down to see entire vasculature -Pick largest vessel to base flap on -Find LPN & MPN brs that supply each of 3 slips of pm, trace them back & divide -Divide origin from ribs & do free flap

Humerus osteology

CRANIAL END -Head: 4x size of glenoid cavity -Anatomical neck: articular margin -Surgical neck: junction w shaft where elderly #s occur, w axillary N & its vessels lie behind -Lesser tubercle: projects in fwd direction, for subscap & TM (medially) attachments -Intertubecular sulcus: has LH biceps in it, covered by transverse humeral ligament. LD inserts into floor, between two majors (PM into lateral side & TM into medial side) -Greater tubercle: projects laterally w 3 facets for SIt muscles (supraspinatus, infraspinatus, tm) SHAFT -Deltoid tuberosity: lateral midshaft, is V shaped for its multipennate fibres -Radial groove: posterior surface, below deltoid tuberosity, for RN & profunda brachii. Above groove is lateral triceps head, below groove is medial head -Nutrient foramen: medial midshaft; above foramen is coracobrachialis insertion; between deltoid & coracobrachialis is flexor surface w beginning of brachialis insertion CAUDAL END -Medial epicondyle: flexor attachments; between ME & trochlear is groove for UN -Lateral epicondyle: extensor group; above is BR & ECRL attachment -Capitulum: circle for radius articulation at elbow jt -Trochlea: spool shaped for ulna at elbow; laterally tilted to help create carrying angle; on posterior side above it is olecranon fossa SURGICAL APPROACH -Superior anterior shaft by deltopectoral groove incision -Midshaft anterolaterally by splitting brachialis vertically, to stay away from BA & MN -Posterior midshaft via interval between long & lateral heads of triceps and splitting the medial head vertically in the midline, avoiding the profunda vessels & RN branches to triceps. OSSIFICATION -Primary centre midshaft at W8 -Secondary centres at head, GT, LT at 1 year old

Lateral arm flap

Common Q: what nerves do you encounter? -PCN forearm and arm runs with PRCA -Radian N runs with PBA then continues w ARCA

Cross section of arm

Draw

Cubital tunnel decompression

Love does subcut transposition -says CuTS is traction>pressure -believes insitu doesnt fix problem & if recurs have to operate on scarred nerve -submuscular creates too much damage and too much scar -subcutaneous is less complicated & puts nerve in new position Cubital tunnel is formed by: -walls: ME & olecranon. -floor: elbow joint capsule & MCL -roof: deep fascia of FCU & Osborne's lig (transverse fibres between ME & olecranon) -Compression sites from 10cm prox to 5cm distal to ME: AMCOF 1) Arcade struthers (MIMS->MH triceps) 2) ME 3) Cubital tunnel 4) Osborne's lig (roof of cubital tunnel) 5) 2 heads FCU UN blood supply 1) Extrinsic -SUCA: from BA 16cm prox to ME -PUCA: from UA 7cm distal to ME - sacrificed w transposition -IUCA (minor) - sacrificed w transposition 2) Intrinsic -Significant fasicular branches that run along UN & allow safe dissection over long distance

Scapular anastomosis

Three arteries (SuDoSu) that connect 1st and 3rd parts of subclavian + 3rd part axillary. One runs over top of scapula, one down medial side, one down lateral side. 1) Suprascapular artery -Arises from thyrocervical trunk, via first part of subclavian artery -Crosses over the superficial transverse scapular lig to supply supraspinous fossa & infraspinous fossa as far as inferior angle 2) Dorsal scapular artery -Arises as direct branch from third part of subclavian artery -Runs down medial scapula, joined by dorsal scapular nerve 3) Subscapular artery and it's branch, circumflex scapular artery -Subscapular arises from 3rd part of axillary artery and runs down lateral scapula edge -Gives off circumflex scapula artery which travels across the infraspinous fossa on dorsal surface of bone

Brachial plexus divisions -location -branches

-Divisions behind middle third of clavicle, they divide BPx into supraclavicular (roots & trunks) & infraclavicular parts (cords & branches). -No branches

Lateral arm flap - classification - vascular anatomy

-7cm pedicle (lateral has 7 letters) -type C FC flap based on post radial collateral artery septocut perfs From Wei -At a point midway between the acromion and the lateral supracondylar ridge, the profunda brachii artery (PBA), arising from the spiral groove, lies in the deep intermuscular septum and divides into two main branches: the middle collateral artery and the radial collateral artery. The middle collateral artery descends in the medial head of the triceps, whereas the radial collateral artery continues to accompany the radial nerve. -Before appearing at the anterolateral aspect of the triceps, the radial collateral artery divides into anterior and posterior branches. The anterior radial collateral artery (ARCA) courses through the lateral intermuscular septum between the brachialis and lateral head of the triceps muscle. It enters the flexor compartment of the upper arm with the radial nerve to descend between the brachialis and brachioradialis muscles to the anterior aspect of the lateral epicondyle, anastomosing with the radial recurrent artery (RRA). -The posterior collateral radial artery (PRCA) runs distally through the lateral intermuscular septum between the triceps posteriorly and the brachialis and brachioradialis anteriorly. It supplies the overlying skin by four or five septocutaneous perforators along the intermuscular septum, and empties into the epicodylar and olecranon plexus. The most distal septocutaneous perforator typically branches off at approximately 4cm proximal to that prominence. The olecranon plexus is supplied from the PRCA but also from the ARCA, the interosseous recurrent artery (IRA), the RRA, the ulnar recurrent arteries, and the inferior ulnar collateral artery. - The Extended LAF (ELAF) is a LAF that includes an extension over and beyond the lateral epicondyle. The use of the ELAF, including the proximal forearm region, enables a lengthening of the pedicle up to 9-16cm as compared with the conventional LAF (6cm). It is important to include the distal septocutaneous perforator above the lateral epicondyle, when harvesting the ELAF.

Axillary vein -formation -course -branches -invested by

-Axillary vein is formed by brachial artery VCs joining with basilic vein near lower border of posterior wall of axilla (has to be basilic because cephalic is still lateral in the deltopectoral groove) -Axillary vein then courses upwards on medial side of axillary artery; leaves axilla by passing through its apex anterior to the 3rd part of subclavian artery. Over the upper surface of first rib, in front of scalenus anterior, it continues as the subclavian vein. -Branches: Tributaries of 2nd & 3rd parts of axillary vein are same as axillary artery branches. Into the first part (ie above pec minor) the cephalic vein enters after having running in deltopectoral groove then piercing the clavipectoral fascia. -Invested by nothing: no axillary sheath around the vein, which is free to expand during times of increased blood flow Cephalic vein turndown -Cephalic vein can be considered as a reliable source of venous drainage when there is a non-availability/unusable of veins during free-flaps in the head and neck region and breast and also when additional source of venous drainage is required in these cases -Amount of vessel required is estimated so as to allow measurement of how much distal dissection is required. Divide cephalic distally and join to vein, allowing flow into axillary vein.

Brachial plexus posterior cord -location -branches

-Cords are in axilla, embracing 2nd part of AA. All 3 post divisions unite to form post cord. 5 ULTRA branches 1) Upper subscapular C5-6: upper subscapularis 2) Lower subscapular C5-6: lower subscapularis & TM 3) Thoracodorsal (used to be called Middle subscapular N): runs down post axilla wall, crosses TM & enters deep LD 4) Radial: terminal br of PC exits axilla via triangular space: Brachiorad, Extensors, Supinator,Triceps 5) Axillary: terminal br of PC exits via quad space w PCHA & V, then divides into ant (deltoid & patch of skin) & post (tm & ULCN) branches

Brachial plexus medial cord -location -branches

-Cords are in axilla, embracing 2nd part of AA. Ant division of lower trunk runs on as medial cord. Ummmm, 5 branches 1) UN C7-T1: runs between artery & vein behind MCN forearm & is most posterior structures on medial arm 2) MCN arm C8-T1: runs down medial side axillary vein to do anteromedial arm skin 3) MCN forearm C8-T1: runs between AA & AV to supply lower arm & medial forearm skin 4) Medial root MN C8-T1: continuation of MC crosses AA to join lateral root, merging lateral to AA to form MN 5) MPN C8-T1: arises from MC post to AA & somewhat lateral to pm, joined by LPN communicating br which passes across AA, then enters pm & PM. Enters axilla by passing under axillary vein, so can be used as guide in ADx MCN of arm aka MABC -MABC descends in the arm anterior and medial to brachial artery -it innervates the skin of anterior & medial surfaces of forearm as far as wrist; -nerve divides into 1-3 branches above the elbow as it travels to the medial epicondyle and olecranon; these nerve branches may pass either proximal or distal to the epicondyle; -use anterior branch for grafts: crosses the elbow between the medial epicondyle and the biceps tendon usually in front of the cubital vein, then travels superficial to the flexor carpi ulnaris muscle, ending 10 cm from the wrist. It is approached through an anteromedial incision on the proximal forearm. It provides a graft of 20 cm.

Brachial plexus lateral cord -location -branches

-Cords are in axilla, embracing 2nd part of AA. At outer border of 1st rib, the upper two anterior divisions unite to form the lateral cord. 3 branches 1) LPN C5-7: runs MEDIAL to pm & pierces CPF to supply PM. Communicates across AA w MPN & through this supplies pm too 2) Musculocutaneous C5-7: descends to supply BBC then LCN forearm 3) Lat root MN C6-7: continuation of lat cord is joined by medial root & embraces artery

Median nerve in arm -origin -course -branches

-Formed at lower border of axilla from union of medial & lateral roots which clasp the axillary artery (AA). -Crosses BA from lat to med at midhumerus, then MATR at CF. Runs on top of Cb then brachialis -Usually no branches in arm (PT usually in forearm)

UN in arm -course -branches

-From med cord BPx, lies in ant compartment med to BA, lying on Cb until midhumerus when pierces MIMS w SUCA & 'ulnar collateral nerve' (br of RN to MH triceps) to run in lower part of post compartment arm -Passes post to ME then lies against medial lig of elbow joint, to enter forearm between humeral & ulnar heads of FCU -No branches in arm -Common Q is relations to UN at midhumerus: it lies deep to anterior aspect of triceps, posterior to brachial vessels & MN

RN in axilla & arm -course -branches

-In axilla arises as continuation of PC. Gives off PCN arm then leaves axilla via lat triangular space w PBA, between long & medial heads triceps -In arm runs w PBA in spiral groove, only touching humerus in lower end. At midpoint humerus pierces LIMS to enter ant compartment to reach CF under cover of BR -Supplies TABBE: Triceps, Anconeus, Brachialis, BR, ECRL in order then divides into PIN & SRN over LE. Gives off long & med tricep head branches prehumerus, along w PCN arm. -After humerus gives off TABBE plus LLCN arm & PCN forearm PCN of forearm -Rarely may be used as a source of graft material. It arises from the radial nerve in the spiral groove and pierces the lateral head of the triceps. It descends the lateral side of the arm, then travels down the dorsal forearm to the wrist, where it communicates with terminal branches of the LABCN. It supplies sensation to the posterolateral forearm. -It is identified via a dorsolateral incision at the elbow between the junction of the brachioradialis and the extensor carpi radialis longus. The PCNF provides 2 to 5 cm of graft material

Musculocutaneous nerve C5,6,7

-Nerve of flexor compartment of arm, supplying all muscles therein (BBC). Runs from lateral cord, behind pec minor & lateral to AA, then runs laterally between 2 heads of coracobrachialis, then runs laterally between biceps & brachialis, joined by branches of the BA & BV -Supplies 2 joints & 3 muscles: GHJ & coracobrachialis, then biceps & brachialis, elbow joint -Now known as lateral cutaneous nerve of forearm, the remaining fibres exit from underneath the biceps tendon, then divides into anterior and posterior branches at the elbow crease. For a nerve graft donor site defect corresponds to the anterolateral forearm, but it also may innervate the volar radial or dorsoradial thumb. For this reason, it is not harvested for grafting a sensory nerve deficit to the thumb. There is a partial or complete overlap of the sensory territory of the superficial radial nerve 75% of the time. The nerve is approached through an anterolateral incision on the proximal forearm, as it passes deep to the cephalic vein. The LABCN provides a nerve graft of 5 to 8 cm

Profunda brachii -course -branches

-PBA enters arm via lower tri space w RN, runs between long & MH on spiral groove then divides into RCA & MCA 1) RCA: runs w RN, divides into ant RCA & post RCA -ARCA: runs w RN to pierce LIMS, enters flexor compartment & joins radial recurrent artery -PRCA: pierces LIMS between triceps & brachialis/BR. Supplies skin via septocut perfs along IMS, dominant for lateral arm flap 2) MCA: Descends in MH triceps, running posterior to LIMS & epicondyle, between BR/brachialis & lateral head triceps, to join interosseous recurrent artery

Brachial plexus - roots

-Roots are between scalenus muscles. 5 roots which are ant rami of C5, 6, 7, 8 & T1 form BPx after giving off their segmental supply to prevertebral & scalenes. 10% of plexuses are pre-fixed (formed from C4- C8) & 10% post-fixed (C6- T2) -Dorsal scapular N (C5): rhomboid major, rhomboid minor, levator scapulae -N to subclavius (C5,6): subclavius -Long Tx (C5-7): passes post to midaxillary line to supply serratus

Brachial plexus trunks -location -branches

-Roots form into 3 trunks, then divide into anterior + posterior divisions to supply flexor+ extensor compartments respectively. -Trunks are are in triangle, and give off only one branch. -Suprascapular N (C5): passes under trapezius through suprascapular notch to supply supraspinatus + infraspinatus

Short scapular muscles

-SItTS w 3 groups of muscles 1) Supraspinatus is Superfulous so is a RC not involved in rotation 2) Infraspinatus and tm laterally rotate 3) TM is Major so goes anterior & therefore Medially rotates along w Subscapularis

Axillary artery branches in detail

1. Sup Tx -Runs forwards to supply both pectoral muscles. 2. TAA -4 CHAP branches pierce CPF separately & radiate away, w pectoral supplying both PM & pm flap 3. Lat Tx -Follows lower border of pm to supply pec muscles incl pm flap, breast, lat thoracic artery flap, serratus flap 4. Subscapular -Runs down post axillary wall & after 4cm divides into A) Circumflex scapular -through triangular space to enter infraspinous fossa & divide: superior horizontal branch arises at scapula spine to supply skin of scapula flap; lower inferomedial branch supplies lateral scapula skin of parascapular flap B) Thoracodorsal -travels between LD & serratus anterior & gives off branches to TIS: TM, intercostals, serratus anterior -then enters deep surface of LD with thoracodorsal nerve 5. ACHA -Runs deep to coracobrachialis & both bicep heads; supplies coracobrachialis flap 6. PCHA -Passes through post wall via quad space to join anterior friend; supplies deltoid fasciocutaneous flap

Pectoralis major

Arises by 2 heads -clavicular: med half anterior clavicle -sternocostal: lat part of anterior manubrium & body of sternum, upper 6 costal cartilages, & aponeurosis of EO over upper aspect of RAM Inserts into lateral lip of bicipital groove by trilaminar tendon, with fibres forming a spiral pattern so that highest fibres at origin insert most anterior, while lowest fibres at origin insert most posterior -anterior lamina: clavicular fibres -middle lamina: manubrial fibres -posterior lamina: sternocostal fibres Type 5 muscle -D: pectoral branch of TAA - emerges below clavicle & enters deep surface of upper border of muscle at approx its midpoint; Wei says this supplies sternocostal head, while small clavicular br of TAA supplies clavicular head -secondary: IMA perforating branches from 1st-6th intercostal spaces - pass through ICS to enter deep surface of muscle 1-2cm from sternal margin -minor: pectoral branch of lateral thoracic artery-emerges below clavicle & enters deep surface of upper border of muscle 3-4cm lateral to TAA branches Planning a) Check PM intact by asking pt to adduct arms by putting hands on waist. b) Pedicle axis: Line from acromion to xiphisternum marks pedicle axis (Wei), then drop line from junction of lateral & medial thirds of clavicle. Where these meet is pedicle location c) Mark PM boundaries d) Mark skin island over PM w planning in reverse e) Keep DP skin flap intact by avoiding incisions across upper skin of chest How to increase length of pedicle to face (based on TAA it should reach infraorbital rim) -Detach from origin & insertion -Tunnel beneath or split clavicle -Skeletonise pedicle -Vein graft

Lat dorsi

Origin is SLIC -Spinous processes T6-T12 -Lumbar fascia post layer -Ilium -Chest: ribs 8-12 Thoracodorsal artery -8cm long -Travels between LD/serratus anterior & gives off branches to TIS: TM, Intercostals, Serratus -Then along with the thoracodosal nerve it enters the deep surface of the muscle in the posterior axilla, 10cm inferior to the muscle insertion into the humerus ARC of rotation -Posteriorly to neck and occipital and parietal skull and across midline in the upper thorax. -Anteriorly to ipsilateral chest and sternum, middle and lower thirds of the face, and superior abdomen. -The standard arc of rotation is extended approximately 5-10 cm by division of LD tendinous insertion & mobilization of the vascular pedicle (ie division of the branch to the serratus anterior muscle and branch of the circumflex scapular artery). Marking -With the patient standing or sitting, forceful contraction of the latissimus dorsi muscle allows the anterior margin of the latissimus at the posterior axillary line to be visualized or palpated and marked. The tip of the scapula is marked with the patient's arms at the sides; this denotes the superior margin of the latissimus dorsi muscle. The posterior vertebral col-umn represents the posterior flap border. The posterior iliac crest is marked to determine the inferior margin of the flap. (note: The inferior marking of a skin island is generally 8 cm superior to the posterior superior iliac crest.) The skin design is placed over the muscle in an oblique or transverse design. Oblique paddle gives largest amount of skin but leaves scar in not ideal direction-sometimes used in chest wall reconstruction, free flaps, or large reconstructions. Transverse scar gives less tissue but more aesthetic scar when transverse skin fold in better direction, so is used in most breast reconstruction cases

Serratus anterior

Slips 1-2 to upper angle of scapula; C5; lateral Tx artery 3-4 to vertebral border scapula; C6; lateral Tx artery 5-8 to inf angle: last 4 to the floor; C7; serratus br of thoracodorsal artery