Anterior Abdominal Wall and Inguinal Canal Flashcards
What are the functions of the abdominal wall?
Forms a firm, yet flexible boundary, which keeps the abdominal viscera in the abdominal cavity and assists the viscera in maintaining their anatomical position against gravity
Protects the abdominal viscera from injury
Assists in forceful expiration by pushing the abdominal viscera upwards
Involved in any action that increases abdominal pressure
What is the superior border of the anterolateral abdominal wall?
Xiphoid process
Costal cartilages of 7-10
Costal margins
What is the inferior border of the anterolateral abdominal wall?
Inguinal ligament
Superior margins of the anterolateral aspects of the pelvic girdle - ASIS to pubic tubercle
What are the lateral borders of the anterolateral abdominal wall?
Muscles continuous with the posterior abdominal wall
What are the quadrants of the abdomen?
Right upper quadrant
Left upper quadrant
Right lower quadrant
Left lower quadrant
What divides the abdomen into its quadrants
The transumbilical plane dividing the abdomen into upper and lower quadrants
A vertical midline plane passing through the linea alba dividing it into left and right quadrants
What are the contents of the right upper quadrant
Right lobe of liver
Gallbladder
Pylorus of stomach
Parts 1-3 of duodenum
Head of pancreas
Right suprarenal gland
Right kidney
Right colic/hepatic flexure
Superior part of ascending colon
Right half of transverse colon
What are the contents of the left upper quadrant?
Left lobe of liver
Spleen
Stomach
Jejunum and proximal ileum
Body and tail of pancreas
Left suprarenal gland
Left kidney
Left colic/splenic flexure
Left half of transverse colon
Superior part of descending colon
What are the contents of the right lower quadrant?
Caecum
Appendix
Most of ileum
Inferior part of descending colon
Right ovary
Right uterine tube
Abdominal part of right ureter
Abdominal part of right spermatic cord
Uterus if enlarged
Urinary bladder if very full
What are the contents of the left lower quadrant?
Sigmoid colon
Inferior part of descending colon
Left ovary
Left uterine tube
Abdominal part of left ureter
Abdominal part of left spermatic cord
Uterus if enlarged
Urinary bladder if very full
What divides the abdomen into its night regions?
The left and right midclavicular lines extending from the mid-clavicle to between the ASIS and pubic crest
Transpyloric plane
Subcostal plane
What are the regions of the abdomen?
Right hypochondrium
Epigastrium
Left hypochondrium
Right flank
Umbilical
Left flank
Right groin
Pubic
Left groin
What are the layers of the anterior abdominal wall, from superficial to deep?
Skin
Subcutaneous fat
Abdominal wall muscles
Tranversalis fascia
Extraperitoneal fat
Peritoneum
How does the subcutaneous tissue differ above and below the umbilicus?
Above the umbilicus it is a single layer of fascia
Below the umbilicus it is divided into 2 layers: a superficial, fatty layer known as Camper’s fascia and a deep, membranous layer known as Scarpa’s fascia
What does Scarpa’s fascia continue inferiorly as?
It continues inferior over the inguinal ligament into the perineal region to continue into the penis in males, and to retain the fat and become part of the mons pubis in females
What are the groups of anterolateral abdominal wall muscles?
Flat and vertical muscles
Which are the flat muscles of the abdominal wall?
External oblique muscle
Internal oblique muscle
Transversus abdominis
What is the continuation of the flat muscles anteriorly and medially?
They continue and sheet-like, tendinous aponeurosis between the midclavicular line and the midline
What doe they form in the midline?
They form the linea alba from the xiphoid process to the pubic symphysis
What are the direction of the external oblique fibres?
Inferomedial
What is the origin of the external oblique muscle?
External surfaces of ribs 5-12
What is the insertion of the external oblique muscle?
Iliac crest
Pubic tubercle
Linea alba
What is the innervation of the external oblique?
Thoracolumbar nerves (T7-T11)
Subcostal nerve (T12)
What is the action of the external oblique?
Bilateral contraction - Trunk flexion, Compresses abdominal viscera, Expiration
Unilateral contraction - Trunk lateral flexion (ipsilateral), Trunk rotation (contralateral)
What direction to the internal oblique muscle fibres run?
In a superomedial direction
What is the origin of the internal oblique muscle?
Inguinal ligament, iliac crest and lumbodorsal fascia
What is the insertion of the internal oblique muscle?
Inferior border of ribs 10-12 and linea alba
What is the innervation of the internal oblique?
T7-L1
What is the action of the internal oblique?
Bilateral contraction - Trunk flexion, Compresses abdominal viscera, Expiration
Unilateral contraction - Trunk lateral flexion (ipsilateral), Trunk rotation (ipsilateral)
What is the origin of the transversus abdominis muscle?
Inguinal ligament
Costal cartilages of ribs 7-12
Iliac crest
Thoracolumbar fascia
What is the insertion of the transversus abdominis muscle?
Conjoint tendon
Linea alba
Xiphoid process
Pubic crest
What is the innervation of the transversus abdominis?
T7-L1
What is the action of the transversus abdominis?
Compressed abdominal contents
What are the vertical muscles of the abdomen?
Rectum abdominis and pyramidalis
What splits the rectus abdominis muscle into 2 vertically?
Linea alba
What surface marking is formed by the lateral surface of the rectus abdominis?
Linea semilunaris
What divides the rectus abdominis muscle horizontally?
Tendinous intersections
What is the origin of the rectus abdominis?
Pubic symphysis and pubic crest
What is the insertion of the rectus abdominis?
Xiphoid process
Costal cartilages of ribs 5-7
What is the innervation of the rectus abdominis?
Anterior rami of T7-T12
What is the action of the rectus abdominis muscle?
Assists the flat muscles in compressing the abdominal viscera
Stabilizes the pelvis during walking
Depresses the ribs
Compresses the abdominal contents
Flexes the vertebral column
Tenses the abdominal wall
What is the origin of the pyramidalis muscle?
Front of the pubis and pubic symphysis
What is the insertion of the pyramidalis muscle?
Linea alba
What is the innervation of the pyramidalis muscle?
Anterior rami of T12
What is the action of the pyramidalis muscle?
Tenses the linea alba
What is the combined action of both the flat and vertical muscles?
Assists in quiet and forces expiration, here pushing the viscera upwards
Assists in coughing and vomiting
Increases the abdominal pressure during parturition, micturition and defaecation
What is the dermatome of the area between the xiphoid process and above the umbilical region?
T7-T9
What is the dermatome for the umbilical region?
T10
What is the dermatome for the area below the umbilical region?
T11-L1
What is the arterial supply to the anterolateral abdominal wall superficially?
Musculophrenic artery superiorly
Inferior epigastric artery inferiorly
Superficial circumflex iliac artery inferiorly
What is the arterial supply to the anterolateral abdominal wall deep?
Superior epigastric
10-11 intercostals
Subcostal
Inferior epigastric
External iliac
What is superficial lymphatic drainage of the anterolateral abdominal wall above the umbilicus?
Axillary nodes
What is the superficial lymphatic drainage of the anterolateral abdominal wall below the umbilicus?
Superficial inguinal lymph nodes
What forms the anterior wall of the rectus sheath?
Above the arcuate line = aponeurosis of EO and IO
Below the arcuate line = aponeurosis of EO, IO and TA
What forms the posterior wall of the rectus sheath?
Above the arcuate line = aponeurosis of IO and TA
Below the arcuate line = tranversalis fascia
What does the median umbilical ligament contain?
Remnant of urachus
What does the medial umbilical ligament contain?
Remnant of umbilical arteries
What does the lateral umbilical ligament contains?
Inferior epigastric arteries
What is the inguinal canal?
An inferomedial, oblique passage approximately 4cm in length, that is directed through the inferior part of the anterior abdominal wall
What are the main contents of the inguinal canal?
Spermatic cord in males
Round ligament of the uterus in females
Blood and lymphatic vessels
Ilioinguinal nerve
Genitofemoral nerve
Which ring is the entrance of the inguinal canal?
Deep inguinal ring
What is the deep inguinal ring located superiorly and lateral to?
It is located superiorly to the middle of the inguinal ligament and lateral to the inferior epigastric artery
What does the deep inguinal ring begin as a invagination of?
The transversalis fascia which forms an opening
Which structures enter the deep inguinal ring?
Vas deferens and testicular vessels in males
Round ligament in females
What are the crura of the inguinal canal?
These are the parts of the EO aponeurosis that lie lateral and medial to, and form the margins of the superficial ring
What does the lateral crus attach to?
The pubic tubercle
What does the medial crus attach to?
Pubic crest
What forms the posterior wall of the inguinal canal?
Transversalis fascia and conjoint tendon
What forms the anterior wall of the inguinal canal?
Aponeurosis of EO and IO
What forms the roof of the inguinal canal?
IO, TA and transversalis fascia
What forms the floor of the inguinal canal?
Inguinal and lacunar ligaments
What are the 2 types of inguinal hernias?
Direct and indirect
What is a direct inguinal hernia?
One that occurs medial to the inferior epigastric vessels, due to abdominal contents herniating through a weak spot in the fascia on the posterior wall of the inguinal canal
What in as indirect inguinal hernia?
One that occurs lateral to the inferior epigastric vessels, due to abdominal contents herniating through the deep inguinal ring as a result of failure of embryonic closure of the processus vaginalis
