Anatomy

Question 1

What is iliopubic tract?

Answer 1

▪ Thickening of fascia transversalis
▪ Iliopectineal arch to the pubic ramus

Question 2

Borders of inguinal canal.

Answer 2

Inguinal canal – 4cm long

▪ Inferior:
• Inguinal ligament
• Lacunar ligament (medial 1/3)
• Iliopubic tract (lateral 1/3)

▪ Anterior
• Aponeurosis of external oblique
• Superficial inguinal ring (medial 1/3)
• Internal oblique (lateral 1/3)

▪ Posterior
• Transversalis fascia
• Conjoint tendon (medial 1/3)
• Deep inguinal ring (lateral 1/3)

▪ Roof
• External oblique aponeurosis
• Internal oblique and transversus abdominis arching fibres
• Transversalis fascia

Question 3

Femoral canal boundaries

Answer 3

o Lacunar ligament (medial), pectineal ligament (inferior), inguinal ligament (superior), femoral vein (lateral)
o Below and lateral to pubic tubercle

Question 4

Contents of spermatic cord

Answer 4

3 arteries
- artery to vas
- artery to cremastaric
- testicular artery
3 veins
3 fascial coverings
- external spermatic fascia (ext oblique)
- cremasteric fascia (internal oblique and transversals abdominis)
- internal spermatic fascia (transversalis fascia)
3 nerves
- genital branch of the genitofemoral nerve
- ilioinguinal nerve
- sympathetics
3 others
- VAS deferens
- lymphatics
- patent processus vaginalis

Question 5

Abodminal wall anatomy

Answer 5

External oblique
o Arises ribs 5-12 → xiphoid, iliac crest, pubic tubercle, ASIS linea alba
o T7-12, subcostal nerve

Internal oblique
o Arises inguinal ligament, iliac crest, lumbodorsal fascia → linea alba, ribs 10-12
o T7-12, ilioinguinal, iliohypogastric nerves

Transversus abdominis
o Arises inguinal ligament, iliac crest, thoracolumbar fascia costal cartilages 7-12 → xiphoid, linea alba, pubic crest
o T6-12, ilioinguinal, lliohypogastric nerves

Question 6

Management of omphalocele and gastroschisis

Answer 6

Congenital umbilical hernia (omphalocele)
o Specialised centre
o If unexpected finding:
▪ Keep baby warm and hydrated
▪ IV Abx
▪ NGT
▪ Handle sac with care to avoid rupture ▪ Cover sac in moist sterile gauze then cover with impervious plastic sheeting or aluminium foil
▪ Transfer to tertiary centre
• Primary closure
• Prosthetic patch
• Skin flap closure
• Silo and staged closure
• Escharotic agents to encourage thickening of sac (giant omphalocele)

Gastroschisis
▪ Place infant in warm, saline-filled plastic organ bag up to nipple line
▪ IVF 1.5x maintenance
▪ IV Abx
▪ OG tube
▪ Repair
• Primary closure
• Patch
• Silo with serial reduction of viscera over 5-7 days
▪ TPN
▪ May need orchidopexy (if testes found extracoelomic)

Question 7

Anatomy of breast

Answer 7

Overview
 In superficial fascia of anterior thoracic wall, from midline to mid-axillary line, 2nd to 6th ribs +/- axillary tail.
 Modified apocrine sweat gland. 15-20 lactiferous ducts converge on nipple (surrounded by areola), sebaceous glands open into areola.
 superficial fascia (continuation of fascia of Scarpa) condenses to form posterior capsule
 suspensory ligaments of Cooper connect dermis to above capsule
 retromammary space between capsule & pectoralis major fascia (relatively avascular)

Blood Supply
 Lateral thoracic artery
o from axillary A at lateral margin of pec minor (2nd part of axillary artery)
 Internal thoracic artery (through intercostal spaces, especially 2nd & 3rd)
 Intercostal arteries (perforating branches)
 Thoracoacromial artery (2nd part of axillary artery)

Venous drainage
 deep veins with arteries to internal thoracic & axillary V’s
 posterior intercostal veins -> vertebral veins

Lymph drainage
 lateral
 axillary & infraclavicular nodes
 medial
 internal thoracic nodes
 75% -> axilla, rest to internal thoracic
 other possible paths: opposite breast, cervical nodes, peritoneal cavity & liver (through diaphragm / rectus sheath), inguinal nodes (anterior abdominal wall)
 involvement of LN by cancer tends to follow an orderly progression proximal -> distal (i.e. pectoral -> central)

Nerve supply
 skin by intercostal N’s
 sympathetic N’s to blood vessels & glands

Development
 modified apocrine sweat gland
 begins to develop from 4th week from mammary ridge of ectoderm along line from axilla to inguinal region

Question 8

Anatomy of pectoralis major.

Answer 8

 Origin:
o clavicular head: medial 1/2 of clavicle
o sternocostal head: lateral manubrium, body of sternum & aponeurosis of ext oblique (also fibres from 1st - 6th costal cartilages)

 Insertion
o trilaminar insertion into lateral lip of intertubercular groove
o anterior lamina: fibres of clavicular head
o intermediate lamina: manubrial fibres
o posterior lamina: sternocostal fibres (insertion runs higher than anterior lamina)

 Nerve supply:
o medial (pierces pectoralis minor) & lateral (pierces clavipectoral fascia) pectoral nerves (from medial & lateral cords of brachial plexus)
o only muscle to be supplied by all 5 segments of brachial plexus (C5-8 & T1)

 Action
o medial rotation, adduction
o abduct & flex to test

Question 9

Anantomy of pec minor.

Answer 9

 Origin: 3rd to 5th ribs near costal cartilages

 Insertion: medial border and superior surface of coracoid process of the scapula

 Action: stabilisation of the scapula (draws inferiorly and anteriorly against the thoracic wall)

 Innervation: medial pectoral nerves

Question 10

Anatomy of Latissimus dorsi

Answer 10

 Forms posterior wall of axilla

 Origin: T7 – S5, posterior part of iliac crest via lumbar fascia, posterior 1 /3 outer lip of iliac crest (reinforced by slips from ribs 8-12

 interdigitate with external oblique)

 Insertion: floor of intertubercular groove (spirals)

 Nerve supply: thoracodorsal nerve (C6, 7, 8 from posterior cord of brachial plexus) (vulnerable in op’s on axilla)

 Action: extends shoulder, medially rotates humerus, adducts shoulder (with pectoralis major), an accessory muscle of both inspiration (costal fibres) & expiration

Question 11

Anatomy of Serratus anterior

Answer 11

 Covers medial wall of axilla

 Origin: ribs 1-8

 Insertion: vertebral border of scapula

 Nerve supply: long thoracic nerve (roots of C5, 6, 7)

 Action: protracts the scapula (pushing), lower 4 digitations assist trapezius in rotating scapula laterally; paralysis =‘winging’

Question 12

Anatomy of axilla.

Answer 12

Borders
 Anterior: Pectoralis major & minor, subclavius, clavipectoral fascia
 Posterior: subscapularis, teres major, lat dorsi
 Medial: upper part of serratus anterior (lower limit = 4th rib)
 Lateral: intertubercular groove
 Floor: axillary fascia
 Apex: clavicle, upper boarder of scapula, outer boarder of 1st rib

Levels of dissection
 I – below lateral edge of pec minor
 II – behind pec minor
 III – above & medial to pec minor

Question 13

Clavipectoral fascia

Answer 13

 Clavicle -> encloses subclavius -> encloses pec minor -> floor of axilla

 Lies ant to neurovascular structures of axilla

 Pierced by
o Lateral pectoral nerve
o Thoraco-acromial artery
o Cephalic vein
o Lymph nodes from pectoral region to apical group of axillary node

Question 14

Anatomy of subscapularis

Answer 14

 Origin: medial 4/5 costal surface of scapula

 Insertion: lesser tuberosity of humerus & medial lip of intertubercular groove

 Nerve supply: upper & lower subscapular N’s (C5, 6 posterior cord of brachial plexus)

 Action: shoulder stability, medial rotation of humerus

 Other: subscapular bursa communicates with shoulder joint

Question 15

Anatomy of teres major

Answer 15

 Origin: dorsal surface of scapula, lateral part of inferior angle

 Insertion: medial lip of intertubercular groove

 Nerve supply: lower subscapular N

 Action: adductor & medial rotator of humerus

Question 16

Anatomy of Axillary artery

Answer 16

 Lateral border of 1st rib to inferior border of teres major -> brachial artery
 enters apex of axilla over 1st digitation of serratus anterior, becomes brachial at lower border of teres major
 invested in axillary sheath (continuation of prevertebral fascia)

 Parts
o 1st part medial pec minor (1 branch)
 Superior thoracic – pectoral muscles

o 2nd part behind pec minor (2 branches)
 Thoracoacromial – clavicular, humeral, acromial and pectoral branches
 Lateral thoracic – pectoral muscles, breast

o 3rd part lateral pec minor (3 branches)
 Subscapular -> thoracodorsal (lat dorsi), circumflex scapular
 Anterior circumflex humeral artery (coracobrachialis, biceps, shoulder joint)
 Posterior circumflex humeral artery -> Travels through quadrangular space -> long and lateral heads of triceps, shoulder joint, anastomoses with profunda brachii artery

Question 17

Anatomy of axillary vein.

Answer 17

 direct continuation of Basilic V – changes name at lower border of teres major
 runs medial then inferior to A
 leaves apex anterior to 3rd part of subclavian A
 corresponding tributaries to branches of A
- plus Cephalic V drains into 1st part
 Separated distally from artery by ulnar nerve and the medial cutaneous nerve of the forearm.
 medial cutaneous nerve of the arm emerges between the axillary A and V
 medial to the vein.
 More proximally the medial head of the median nerve emerges from between A & V.
 At an even higher level the medial pectoral nerve also emerges from between A & V.

Question 18

Anatomy of intercostobrachial nerve.

Answer 18

 Cutaneous branch from 2nd intercostal N
 Exits b/w 1st & 2nd ribs -> across axilla -> skin on medial upper arm
 Often 2nd intercostobrachial from 3rd intercostal N

Question 19

Lymph nodes of Axilla

Answer 19

 Anterior / Pectoral group o with lateral thoracic A
 Posterior / Subscapular group
o along subscapular A
 Lateral group
o along medial side of axillary V
 Central group
 Apical group
o drain via subclavian lymph trunk to supraclavicular nodes

Question 20

Anatomy of brachial plexus.

Answer 20

Roots (5)
 anterior rami of C5, 6, 7, 8, T1 (after segmental supply to prevertebral & scalene muscles)
 lie behind scalenus anterior & emerge on scalenus medius
 Branches:
 C5: Dorsal scapular N
 C5, 6: N to subclavius (in front of roots)
 C5, 6, 7: Long thoracic N

Trunks (3)
 cross posterior triangle of neck
 Superior (C5,6):
o Suprascapular N (C5, 6)
 Middle (C7)
 Inferior (C8, T1)

Divisions (2)
 anterior & posterior: behind clavicle
 Posterior divisions -> posterior cord
 Anterior divisions -> lateral & medial cords

Cords (infraclavicular part) (3)
 Named for their relationship to the 2nd part of the axillary artery

Lateral (3)
 Lateral Pectoral N (C5, 6, 7)
 Musculocutaneous N (C5, 6)
 Lateral root of Median N

Posterior (5)
 Upper subscapular (C5, 6)
 Thoracodorsal (C6, 7, 8)
 Lower subscapular (C5, 6)
 Axillary (C5, 6)
 Radial (C5, 6, 7, 8, T1)

Medial (5)
 Medial Pectoral N (C8, T1)
 Medial root of Median N (C8, T1)
 Medial Cutaneous N of arm (C8, T1)
 Medial Cutaneous N of forearm (C8, T1)
 Ulnar N (C7, 8, T1)

Question 21

Anatomy of long thoracic nerve.

Answer 21

C5, 6, 7
 path: behind roots, emerges from lateral border of scalenus medius & passes into axilla on serratus anterior (posterior to midaxillary line)
 Passes vertically downward to enter axilla
 In proximal axilla it is superficial to serratus anterior fascia, embedded in fatty tissue
 Travels medially & at level of 4th & 5th intercostal spaces, pierces fascia to lie on muscle
 Courses behind mid-axillary line & posterior to lateral thoracic perforating vessels
 Supplies: serratus anterior

Question 22

Anatomy of lateral pectoral nerve.

Answer 22

C5, 6, 7
o path: crosses in front of axillary A & V at level of medial border of pec minor to communicate with medial pectoral N, pierces clavipectoral fascia
o supplies: pectoralis major & minor

Question 23

Anatomy of musculocutaneous nerve

Answer 23

C5, 6
o path: through coracobrachialis, becomes Lateral cutaneous N of forearm
o supplies: coracobrachialis, biceps, brachialis

Question 24

Anatomy of thoracodorsal nerve.

Answer 24

C6, 7, 8
o path: runs down post axillary wall behind axillary A & V to lie on subscapularis -> enter deep surface of lat dorsi, lies ant to subscapular A then thoracodorsal A (vulnerable in axillary surgery)
o supplies: latissimus dorsi

Question 25

Anatomy of axillary nerve

Answer 25

C5, 6
o path: backwards through quadrangular space
o anterior branch: winds behind humerus to deep surface of deltoid then skin
o posterior branch: winds around post border of deltoid to become Upper Lateral cutaneous N of arm
o supplies: shoulder joint, deltoid, teres minor, skin

Question 26

Anatomy of radial nerve

Answer 26

C5, 6, 7, 8, T1
o path: lies on latissimus dorsi tendon, through triangular space
o supplies: long, medial & lateral heads of triceps (in that order & before winding ‘round spiral groove), skin via Post Cutaneous N of arm

Question 27

Anatomy of medial pectoral nerve.

Answer 27

C8, T1
o path: arises behind axillary A, emerges b/w A & V -> pierces pectoralis minor to supply pectoralis major (joined by lateral pectoral N)
o supplies: pectoralis minor & major

Question 28

Anatomy of axillary artery

Answer 28

o Lateral margin 1st rib → lower margin of teres major
o Parts
▪ A1 – superior to pec minor
▪ A2 – posterior to pec minor
▪ A3 – inferior to pec minor
o Branches
▪ Screw the lawyers save a patient
▪ A1:
• Superior thoracic
▪ A2:
• Thoracoacromial
• Lateral thoracic
▪ A3:
• Subscapular → thoracodorsal
• Anterior circumflex humeral
• Posterior circumflex humeral

Question 29

Anatomy of Subclavian artery

Answer 29

o Aortic arch or brachiocephalic trunk to lateral margin of 1st rib
o Parts:
▪ S1 – medial to scalenus anterior
▪ S2 – posterior to scalenus anterior
▪ S3 – lateral to scalenus anterior
o Branches
▪ Vit C+D
▪ S1:
• Vertebral
• Internal mammary
• Thyrocervical
o Inferior thyroid
o Suprascapular
o Ascending cervical
o Transverse cervical
▪ S2:
• Costocervical
o Superior intercostal
o Deep cervical
▪ S3:
• Dorsal scapular

Question 30

Anatomy of thoracic duct

Answer 30

Course

Originates atcisterna chyli in midline at level of L2

Passes cephalad through the diaphramatic hiatus

Ascends on right side of thoracic spine

Crossed toleft side at level of T4

Continues along theleft side of oesophagus

Arches forward and laterally at the root of the neck

Emerges betweenleft subclavian and common carotid arteries

Passes between internal jugular vein and scalenus anterior muscle

Joinsleft subclavian vein at eh angle it makes with IJV