19-01-23 - Abdominal wall 1: Anterolateral wall, inguinal region and hernias Flashcards
Learning outcomes
- Describe the regions of the abdominal wall as appropriate to clinical examination
- Describe the organization of the skin and fasciae of the anterior and lateral abdominal walls
- Describe the musculature of the abdominal walls: external and internal oblique; transversus and rectus abdominis
- Describe the structure of the rectus sheath
- Describe the actions of the muscles of the abdominal wall
- Describe the structures of lacunar ligament, pectineal ligament and the conjoint tendon and explain their clinical importance
- Describe the structure, contents and function of the inguinal canal
- Describe the position and boundaries of the deep and superficial inguinal rings
- Explain the anatomical correlates of inguinal hernias
How is the abdomen divided into 4 quadrants?
- The abdomen can be split into quadrants through:
1) Trans-umbilical plane − L3/4 intervertebral disc 9
2) Median (midsagittal) plane − through the xiphoid process & pubic symphysis
What 3 lines separate the abdomen into the 9 regions?
What are the 9 regions the abdomen can be divided into?
- 3 lines that separate the abdomen into the 9 regions:
1) Midclavicular line
* Midpoint of the clavicle
2) Subcostal plane
* L3 vertebra
* Lowest point of the costal margins (10th costal cartilages)
3) Transtubercular / intertubercular plane
* L5 vertebra
* Iliac tubercles
- 9 regions the abdomen can be divided into:
1) Right hypochondrium
2) Epigastric region
3) Left hypochondrium
4) Right lumbar region (flank, loin)
5) Umbilical region
6) Left lumbar region
7) Right inguinal region (groin)
8) Hypogastric region (pubic, suprapubic)
9) Left inguinal region
What are the 6 layers of the lateral abdominal wall?
What is underneath all of these layers?
- 6 layers of the lateral abdominal wall:
1) Skin (Epidermis+dermis)
* Attached to subcutaneous tissue loosely except at umbilicus
2) Superficial fascia (SF)
* Subcutaneous fatty layer (Camper’s fascia)
* Deep membranous layer (Scarpa’s fascia)
3) Abdominal muscles with their investing fasciae
4) Transversalis fascia
5) Extraperitoneal fat
6) Parietal peritoneum
* These layers then lead into the peritoneal cavity
What is the perineum?
What are the 2 layers of superficial abdominal fascia continuous with?
- The perineum is the area between the anus and the posterior part of the external genitalia
- Fatty layer of superficial abdominal fascia (Camper’s) is continuous with the superficial layer of perineal fascia (Cruveilhier’s)
- Membranous layer of superficial abdominal fascia (Scarpa’s) is continuous with membranous layer of superficial perineal fascia (Colle’)
What do abdominal wall muscles consist of?
What are the 5 abdominal muscles?
What are 6 functions of abdominal wall muscles?
What 3 sources of nerves are abdominal wall muscles innervated by?
- The abdominal wall muscles consist of 3 flat muscles and a vertical strap-like muscle (+pyramidalis):
1) Rectus abdominis (vertical strap like muscle)
2) External oblique muscle (flat muscle)
3) Internal oblique muscle (flat muscle)
4) Transversus abdominis (flat muscle)
5) Pyramidalis - 6 functions of abdominal wall muscles:
1) Support abdominal contents
2) Raise intra-abdominal pressure
3) Withstand pressure from descent of the diaphragm
4) Respiration
5) Support vertebral column
6) Flex, laterally flex and rotate the trunk - 3 sources of nerves abdominal wall muscles are innervated by:
1) Thoraco-abdominal nerve (7th - 11th intercostal nerves)
2) Subcostal nerve
3) L1
Label these hip bones
Bones of the pelvic girdle
What does the rectus abdominis (6 pack) consist of?
What is each muscle closed in?
What is this formed by?
How many tendinous intersections do the rectus abdominis muscles have?
Where do the rectus abdominis muscles originate and insert?
What is the function of the rectus abdominis muscles?
- The rectus abdominis (6 pack) consist of two flat and parallel muscles separated by linea alba (a connective tissue)
- Each rectus abdominis is enclosed in rectus sheath - formed by the aponeuroses of the flat muscles of the abdominal wall
- The rectus abdominal muscles have 3 tendinous intersections
- The rectus abdominis muscles originate on the pubic crest and pubic symphysis
- The rectus abdominis muscles insert on the 5th – 7th costal cartilages and Xiphoid process
- The rectus abdominis muscles stabilize the pelvis during gait
What is the rectus sheath?
What does it contain?
What does the rectus sheath consist of?
What is an aponeurosis?
- The rectus sheath is the durable, resilient, fibrous compartment that contains both the rectus abdominis muscle and the pyramidalis muscle.
- The rectus sheath consists of the fascial coverings (aponeurosis) of the:
1) External oblique
2) Internal oblique
3) Transversus abdominis muscles - An aponeurosis is a thin sheath of connective tissue that helps connect your muscles to your bones
What is the arcuate line?
What structures enter the rectus sheath?
- The arcuate line is the inferior border of aponeuroses of transversus abdominis and posterior layer of the internal oblique behind rectus abdominis
Describe the rectus sheath just below the umbilicus (above arcuate line).
What is the linea semilunaris?
What is it the site of?
What is the linea alba the site of?
- Describe the rectus sheath just below the umbilicus (above arcuate line):
- The external oblique aponeurosis goes along the anterior surface of the rectus abdominis muscles
- The internal oblique muscle aponeurosis splits into 2, which one end going over the anterior edge and one going over the posterior edge of the rectus abdominis
- The transversus abdominis aponeurosis goes along the posterior edge of the rectus abdominis
- These structures sit onto of the transversalis fascia and the parietal peritoneum
- The linea semilunaris (aka semilunar line) is a vertical, curved structure that runs along the lateral edges of the rectus abdominis muscle in the anterior abdominal wall.
- It is the site of union where tendons of the lateral abdominal muscles meet the sheath surrounding the rectus abdominis muscle, also known as the rectus sheath
- The linea alba is the site in the midline where all aponeuroses of the abdominal wall muscles fuse
Describe the rectus sheath just above the pubis (below arcuate line)
- Describe the rectus sheath just above the pubis (below arcuate line):
- The aponeurosis of the external oblique, internal oblique and transversus abdominis muscles goes over the anterior surface of the rectus abdominis muscles
- These structures sit onto of the transversalis fascia and the parietal peritoneum
Where does the external oblique muscle originate?
What 5 places does the external oblique muscle insert?
What direction do the external oblique muscle fibres run?
- The external oblique muscle originates on the lower 8 ribs
- 5 places the external oblique muscle inserts:
1) Iliac crest
2) Anterior superior iliac spine (ASIS)
3) Linea alba
4) Xiphoid process
5) Pubic tubercle - The external oblique muscle fibres run infero-medially (like putting hands in pockets)
What is the inguinal ligament the lower border of?
Where does it attach to and extend between?
How is the lacunar ligament formed?
What does the lacunar ligament form?
- Inguinal ligament is the lower border of the aponeurosis of the external oblique muscle
- It attaches to and extends between the anterior superior iliac spine (ASIS) and the pubic tubercle
- The lacunar ligament is formed when some of the fibres from the medial end of the inguinal ligament turn posterolaterally and attach to pubic pecten (pectineal line)
- The lacunar ligament forms the medial border of the femoral ring (base of femoral canal)
Inguinal and lacunar attachment diagrams
What is the superficial inguinal ring?
What does it serve as the opening to?
- The superficial inguinal ring is the defect on the aponeurosis of the external oblique, just above the pubic tubercle
- The superficial inguinal ring serves as the superficial (medial) opening of the inguinal canal that connects the abdominal cavity to the scrotum
Where does thoraco-lumbar fascia pass between?
What does it surround?
What 2 muscles does it provide attachment to?
What can the weak area in the thoraco-lumbar fascia cause?
- Thoraco-lumbar fascia passes from the iliac crest to the lumbar vertebrae and ribs
- It surrounds the back muscles
- Thoraco-lumbar fascia provides attachment to the transversus abdominis & internal oblique muscles but not external oblique
- A weak area in the thoraco-lumbar fascia between muscles can be an area for herniation
What 3 places does the internal oblique muscle originate?
What 4 places does the internal oblique muscle insert?
What are the 2 innervations to the internal oblique muscle?
Describe how the superior and inferior fibres of the internal oblique muscle run
- 3 places does the internal oblique muscle originate:
1) Thoracolumbar fascia
2) Iliac crest (anterior 2/3)
3) Lateral 2/3 of inguinal ligament - 4 places does the internal oblique muscle insert:
1) Inferior 3-4 ribs
2) Linea alba
3) Xiphoid process
4) Pubic tubercle - 2 innervations to the internal oblique muscle:
1) T7-12
2) Iliohypogastric nerve (L1) - The superior fibres of the internal oblique muscle run superiorly
- The inferior fibres run inferiorly to form an arch which then ends in the conjoint tendon
What are the 4 places the transversus abdominis muscle originates?
What are the 3 places the transversus abdominis inserts?
What are the 2 innervations to the transversus abdominis?
- 4 places the transversus abdominis muscle originates:
1) Thoracolumbar fascia
2) Iliac crest
3) Lateral 1/3 of inguinal ligament
4) Inferior 6 ribs + Costal cartilages - 3 places the transversus abdominis inserts:
1) Linea alba
2) Xiphoid process
3) Pubic tubercle - 2 innervations to the transversus abdominis:
1) T7-12
2) Iliohypogastric nerve (L1)
What is another name for the conjoint tendon?
How is the conjoint tendon formed?
What 2 places does the conjoint tendon attach?
What does the conjoint tendon support?
Where is the spermatic cord found?
- The conjoint tendon is also known as the Inguinal falx
- The conjoint tendon is formed when the inferior fibres of internal oblique arising from the inguinal ligament arch medially over the spermatic cord and unite with the transversus abdominis aponeurosis
- 2 places the conjoint tendon attaches:
1) Pubic crest
2) Pectineal line behind the superficial inguinal ring - The conjoint tendon supports and is immediately behind the superficial inguinal ring, which is the opening of the inguinal canal
- The spermatic cord is found in the inguinal canal
What is the transversalis fascia?
What groups of people can it be inured in?
- The transversalis fascia is a thin layer of connective tissue that lines the transversus abdominis muscle internally
- May be injured in athletes
What is the inguinal canal?
What does it connect in men and women?
What are the 2 openings of the inguinal canal?
How is the inguinal canal created?
What are the contents of the inguinal canal in men and women?
What are the 2 nerve supplies of the inguinal canal?
How do they each enter the inguinal canal?
How can a hernia be caused if one of these nerve supplies is severed?
- The inguinal canal is a passage through the anterior abdominal wall
- The inguinal canal connects the abdominal cavity to:
1) The scrotum in males
2) The labia majora in females - 2 openings of the inguinal canal:
1) Deep inguinal ring
2) Superficial inguinal ring - The inguinal canal is created by the descent of the testis “pushing” through the abdominal wall muscles and/or their aponeuroses
- Contents of the inguinal canal:
1) Spermatic cord in males
2) Round ligament of uterus (ligamentum teres uteri) in females - 2 nerve supplies of the inguinal canal:
1) Genital branch of genitofemoral nerve (L1/2)
* Enters through the deep inguinal canal and leaves through the superficial inguinal canal
2) Ilioinguinal nerve (L1)
* Doesn’t enter through the deep inguinal canal, but exits through the superficial inguinal canal
* Supplies the conjoint tendon
* If severed, the conjoint tendon is weakened and wont be able to support the superficial inguinal ligament as well, as it sits just behind it
* This can cause a hernia
What is the deep inguinal ring an opening to?
What is it made from?
Where can it be found?
What are 2 reference point for the deep inguinal ring?
- The deep inguinal ring is an opening in the transversalis fascia to the inguinal canal
- The deep inguinal ring is made from an invagination of transversalis fascia
- It is found in the lateral inguinal fascia
- 2 reference point for the deep inguinal ring:
1) lateral to the lateral umbilical fold (covering inferior epigastric vessels)
2) about 1cm above the midway between the anterior superior iliac spine (ASIS) & pubic tubercle (midpoint of the inguinal ligament)
Where is the superficial inguinal ring found?
What is it supported by?
- The superficial inguinal ring is a triangular opening in the external oblique aponeurosis
- It is supported from behind by the conjoint tendon
What are the 2 anterior boundaries of the inguinal canal?
What are the 2 posterior boundaries of the inguinal canal?
What are the 2 roof boundaries of the inguinal canal?
What are the 2 floor boundaries of the inguinal canal?
- 2 anterior boundaries of the inguinal canal:
1) External oblique
2) Internal oblique laterally - 2 posterior boundaries of the inguinal canal:
1) Conjoint tendon medially
2) Transversalis fascia laterally - 2 roof boundaries of the inguinal canal:
1) Arching inferior edges of internal oblique & transversus abdominis - 2 floor boundaries of the inguinal canal:
1) Inguinal ligament
2) Lacunar ligament medially
What are hernias?
Where does it occur?
Where do inguinal hernias appear?
Where does a femoral hernia appear?
- A hernia is a condition in which part of an organ is displaced and protrudes through the wall of the cavity containing it
- Hernias occurs in weaker areas
- An inguinal hernia usually appears above & medial to the pubic tubercle
- A femoral hernia passes and appears below and lateral to the pubic tubercle
