UNIT 2: anterior abdominal wall and inguinal region - clinical relevance

Question 1

what are the nine subdivisions of the abdomen? how is it split?

Answer 1

split by 4 planes: two mid-clavicular planes, subcostal plane (10th costal cartilage) and transtubercular plane (iliac tubercles/ body of T5)
subdivsions: right/left hypochondriac; right/ left lumbar; right/left iliac; epigastric; umbilical; hypogastric

Question 2

how can the abdomen be split into quadrants?

Answer 2

split by 2 planes : median plane and transumbilical plane (passes between L3/4)

Question 3

what are the superior/ inferior borders of the anterolateral wall?

Answer 3

superior: cartilage of 7th to 10th ribs/ xiphoid process of sternum
inferior: inguinal ligament/ pelvis bones

Question 4

what are the layers of fascia in the abdominal wall?

Answer 4

skin// subcutaneous tissue (camper fascia = fat/scarper fascia = membranous// alternating layers of investing fascia (aka epimysium) - superficial/ intermediate/ deep with EO/ IO/ TA // transversalis fascia // extraperitoneal fat // parietal peritoneum

Question 5

what are the two vertical muscles of the abdominal wall?

Answer 5

rectus abdominis - fibres run between tendinous connnections with linea alba down midline - rectus sheath attaches onto linea alba and encloses the rectus sheath = flexion of lumbar spine
pyramidalis - arises from pubic crest inserts onto linea alba = tenses linea alba

Question 6

what is the arcuate line?

Answer 6

distinct lower border of posterior rectus sheath where it transitions to transversalis fascia

Question 7

what are the three flat muscles of the abdominal wall? - describe the direction of the fibres

Answer 7

• external oblique - fibres run inferomedially \
• internal oblique - fibres fan out
• transversus abdominis - fibres transverse except lower ones inferomedially \
• fibres of muscles end in aponeurosis - blend into linea alba form rectus sheath

Question 8

which muscle does the external oblique interdigitate with? what does the free lower border of the EO form?

Answer 8

interdigitates with serratus anterior
inguinal ligament (anterior superior iliac spine to pubic tubercle)

Question 9

what are the movements/ function of the anterolateral abdominal muscles?

Answer 9

• rotation of lumbar spine
• compress/ support abdominal viscera so increases intra- abdominal pressure elevating the diaphragm - expel air
• provides force for defecation/ micturition (wee)/ parturition (giving birth)

Question 10

describe the vasculature of the anterior abdominal wall

Answer 10

superior part of wall supplied by superior epigastric artery (continuation of internal thoracic artery)
inferior part of wall supplied by inferior epigastric artery - enters sheath below arcuate line

venous drainage by thoraco-epigastric vein formed by anastomosis of femoral and axillary veins - drains into IVC

Question 11

describe lymphatic drainage of abdominal wall

Answer 11

superficial lymphatic vessels:
if above transumbilical plane - drain into axillary lymph nodes
if below plane - drains into superficial inguinal nodes
deep lymphatic vessels: drain into external lymph nodes

Question 12

describe the innervation of the abdominal wall

Answer 12

motor/ sensory innervation = thoraco-abdominal nerves continuation of lower intercostal nerves (T7-11)
autonomic innervation - sympathetic trunk/ aortic plexus/ vagus nerve

Question 13

what are the two associated ligaments of the inguinal ligament?

Answer 13

lacunar ligament and pectineal ligament = form triangular extension of inguinal ligament

Question 14

what structures run through the inguinal canal?

Answer 14

in males= spermatic cord
in females = round ligament
- also ilio-inguinal nerve travels down the canal

Question 15

what are the openings of the inguinal canal?

Answer 15

deep inguinal ring (internal) - midpoint of the inguinal ligament - formed by invagination of transversalis fascia
superficial inguinal ring (external) - formed by invagination of EO aponeurosis

Question 16

how are the walls of the inguinal canal formed?

Answer 16

floor = inguinal ligament - reinforced medially by lacunar
roof/ posterior: mainly transversalis fascia reinforced by arching fibres of internal oblique and transversus abdominus which join to form conjoint tendon inserting onto the pubic crest

Question 17

what are the the three layers of fascia of the spermatic cord?

Answer 17

external spermatic fascia - derived from EO
cremaster muscle/ fascia
internal spermatic fascia

Question 18

what blood vessels are found in the spermatic cord?

Answer 18

• pampiniform plexus - venous drainage of testes into testicular vein (right - drains into IVC/ left - drains into left renal vein)
• cremasteric artery/ vein - supplies cremasteric fascia/ muscle
• testicular artery
• artery to vas deferens

Question 19

describe the vas deferens and its function

Answer 19

three layers

• inner longitudinal layer
• intermediate circular layer
• outer longitudinal layer
  functions: transports sperm - fast movement due to autonomic innervation of muscle fibres

Question 20

give another function of the pamipiniform plexus

Answer 20

heat exchanger - cools arterial blood before reaches testes

Question 21

describe the features of the testes and the epididymis

Answer 21

testes - series of lobules containing seminiferous tubules supported by interstitial tissue and lined with sertolic cells

• parietal sac = tunica vaginalis
• inner layer = tunica albuginea

epididymis connected to testes by efferent tubules
it has three parts: head, body, tail (origin of vas deferens)

Question 22

what are the six common causes of abdominal protrusion and what can eversion of umbilicus show?

Answer 22

food, fluid, fat, faeces, flatus (gas) and fetus
- eversion = increased intra-abdominal pressure - resulting from ascites (abnormal accumulation of serous fluid in peritoneal cavity) or large mass

Question 23

what is the cremasteric reflex?

Answer 23

stroking medial thigh leads to contraction in cremasterr muscle - lift up testes - shows spinal nerves are not damaged

Question 24

what causes testicular torsion and what is its effect?

Answer 24

spasms of cremaster muscle forces testicle to spin around its own cord - strangulation of testicular artery (cut off blood supply) - necrosis of testes

Question 25

what are the two types of testicular cancer?

Answer 25

testis - metastasise in lumbar lymph nodes

scrotum - metastasise in superficial inguinal lymph nodes

Question 26

what is an inguinal hernia and what are the two types?

Answer 26

inguinal hernia = protusion of organ/ fascia through parietal peritoneum

• Indirect (congenital): peritoneal sac enters canal through deep inguinal ring (entire length) - lateral to inferior epigastric vessels - commonly passing into scrotum
• Direct (acquired): peritoneal sac enters through posterior wall of canal - only travels 1/3 of canal - medial to epigastric vessels

Question 27

give five contributors to enlarged scrotum

Answer 27

• epididymitis- inflammation of epididymis - caused by infection
• inguinal hernia
• hydrocoele - serous fluid in tunica vaginalis
• haematocoele - blood in tunica vaginalis
• variocoele - dilation of vessels draining the testes - “bag of worms”