Abdomen overview & Anterolateral abdominal wall Flashcards
What structure ensures the containment of the abdominal organs and their contents?
- The musculo-aponeurotic walls anterolaterally,
- the diaphragm superiorly, and
- the muscles of the pelvis inferiorly.
The anterolateral musculo-aponeurotic walls are suspended between and supported by what structures?
By two bony rings, the inferior margin of the thoracic skeleton superiorly and the pelvic girdle inferiorly lined by a semi-rigid lumbar vertebral column in the posterior abdominal wall.
Interposed between the more rigid thorax and pelvis, the musculo-aponeurotic provides what functions?
It encloses the abdomen to protect its contents while providing the flexibility required by respiration, posture and locomotion.
TEST YOURSELF FIG2.1 P.183
TEST YOURSELF FIG2.1 P.183
The multi-layered musculo-aponeurotic abdominal walls not only contract to increase intra-abdominal pressure, but can also distend. What is the purpose of this distension?
To accommodate expansions caused by pregnancy, fat deposition or pathology.
The anterolateral abdominal wall and several organs lying against the posterior wall are covered on their internal aspects with what?
A serous membrane or peritoneum (serosa) that reflects onto the abdominal viscera to cover organs such as the stomach, intestine, liver, and spleen.
What is the peritoneal cavity?
It is a potential space formed between the walls of the viscera that normally contain only enough extracellular (parietal) fluid to lubricate the membrane covering most of the surfaces of the structures forming or occupying the abdominal cavity.
TEST YOURSELF FIG2.3 P.184
TEST YOURSELF FIG2.3 P.184
TEST YOURSELF FIG 2.4 P. 186
TEST YOURSELF FIG 2.4 P. 186
List the nine (9) regions of the abdominal cavity are separated by two sagittal (vertical) and two transverse planes. They are used to describe the location of abdominal organs, pains or pathologies. What are they?
- RH – right hypochondrium
- RL – right flank (lateral region)
- RI – right inguinal (groin)
- E – epigastric
- U – umbilical
- P – pubic
- LH – left hypochondrium
- LL – left flank (lateral region)
- LI – left inguinal (groin)
What ten (10) structures are located in the right upper quadrant (RUQ)?
- Liver: right lobe
- Gallbladder
- Stomach: pylorus
- Duodenum: parts 1-3
- Pancreas: head
- Right suprarenal gland
- Right kidney
- Right colic (hepatic flexure)
- Ascending colon: superior part
- Transverse colon: right half
What ten (10) structures are located in the left upper quadrant (LUQ)?
- Liver: left lobe
- Spleen
- Stomach
- Jejunum and proximal ileum
- Pancreas: body and tail
- Left kidney
- Left suprarenal gland
- Left colic (splenic) flexure
- Transverse colon: left half
- Descending colon: superior part
What ten (10) structures are located in the right lower quadrant (RLQ)?
- Cecum
- Appendix
- Most of the ileum
- Ascending colon: inferior part
- Right ovary 6. Right uterine tube
- Right spermatic cord: abdominal part
- Uterus (if enlarged)
- Right ureter: abdominal part
- Urinary bladder (if very full)
What eight (8) structures are located in the left lower quadrant (LLQ)?
- Sigmoid colon
- Descending colon: inferior part
- Left ovary
- Left uterine tube
- Left spermatic cord: abdominal part
- Uterus (if enlarged)
- Left ureter: abdominal part
- Urinary bladder (if very full)
What structures define the abdominal wall?
It is a continuous structure consisting of musculo-aponeurotic structure that extends to the posterior wall which then incorporates the lumbar region on of the vertebral column.
What defines the boundary between the anterior and lateral walls of the abdominal cavity?
Nothing, it is a continuous structure that contains muscles and cutaneous nerves and extends from the thoracic cage to the pelvis.
What are the boundaries of the anterolateral abdominal wall?
- Superiorly by the cartilages of the 7-10th ribs and the xiphoid process of the sternum
- Inferiorly by the inguinal ligament and the superior margins of the anterolateral aspects of the pelvic girdle (iliac crests, pubic crests, and pubic symphysis)
What structures are contained in the anterolateral abdominal wall?
- Skin
- Subcutaneous tissue (superficial fascia) composed mainly of fat, muscles and their aponeuroses
- Deep fascia
- Extraperitoneal fat
- Parietal peritoneum
What is the key feature of the musculotendinous layer of the anterolateral abdominal wall?
It’s three layers of muscles run in different directions and is similar to that of the intercostal spaces in the thorax
Superior to the umbilicus, the subcutaneous tissue is consistent with that found in most regions. What is the difference with the subcutaneous tissue inferior to the umbilicus.
The deepest part of the subcutaneous tissue is reinforced by many elastic and collagen fivers and has two layers
- the superficial fatty layer (Camper fascia) of subcutaneous tissue; and
- the deep membranous layer (Scarpa fascia) of subcutaneous tissue.
What does the superficial fatty layer (camper fascia) and deep membranous layer (Scarpa fascia) of subcutaneous tissue form as it continues inferiorly?
This membranous layer continues inferiorly into the perineal region as the superficial perineal fascia (colles fascia), but not into the thighs.
What is an aponeuroses?
A flat expanded tendon.
What is an epimysium?
The outer fibrous connective tissue layer surrounding all muscles.
What constitutes the endoabdominal fascia?
The membranous and areolar sheets of epimysium from the internal aspects of the abdominal walls. Although continuous, it is named according to the muscle or aponeurosis it is lining.
What is the name of the endoabdominal fascia lining the deep surface of the transversus abdominis muscle and its aponeurosis?
It is the transversalis fascia.
Describe the parietal peritoneum and its location.
It is the glistening lining of the abdominal cavity formed by a single layer of epithelial cells and supporting connective tissue. It is internal to the transversalis fascia and is separated from by a variable amount of extraperitoneal fat.
What is the origin of the external oblique muscles?
The external surfaces of the 5th – 12th ribs
What is the insertion point of the external oblique muscles?
The linea alba, pubic tubercle and the anterior half of the iliac crest
What innervates the external oblique muscles?
The thoraco-abdominal nerves (T7-T11 spinal nerves) and subcostal nerve.
What are the main actions of the external oblique muscles?
To compress and support abdominal viscera, flex and rotate the trunk.
What is the origin of the internal oblique muscles?
The thoracolumbar fascia, anterior two thirds of the iliac crest and connective tissue deep to the lateral third of the inguinal ligament.
What is the insertion point of the internal oblique muscles?
The inferior border of the 10th – 12th ribs, the linea alba and the pectin pubis via conjoint tendon (inguinal falx).
What innervates the external internal muscles?
The thoraco-abdominal nerves (anterior rami of T6-T12 spinal nerves) and the first lumbar nerves.
What are the main actions of the internal oblique muscles?
To compress and support abdominal viscera, flex and rotate the trunk.
What is the origin of the transversus abdominis muscles?
The internal surfaces of the 7th – 12th costal cartilages, thoracolumbar fascia, iliac crest and connective tissue deep to the lateral third of the inguinal ligament
What is the insertion point of the transversus abdominis muscles?
The liniea alba with aponeurosis of the internal oblique, pubic cres and pectin pubis via conjoint tendon (inguinal falx).
What innervates the transversus abdominis muscles?
The thoraco-abdominal nerves (anterior rami of T6-T12 spinal nerves) and the first lumbar nerves.
What are the main actions of the transversus abdominis muscles?
To compress and support abdominal viscera
What is the origin of the rectus abdominis muscles?
The pubic symphysis and pubic crest
What is the insertion point of the rectus abdominis muscles?
The xiphoid process and 5th – 7th costal cartilages
What innervates the rectus abdominis muscles?
The thoraco-abdominal nerves (anterior rami of T6 – T12 spinal nerves)
What are the main actions of the rectus abdominis muscles?
They flex the trunk (lumbar vertebrae) and compress the abdominal viscera. They also stabilise and control tile of the pelvis (antilordosis)
What muscles act as antagonists of the diaphragm to produce expiration?
All the muscles of the anterolateral abdominal wall (external and internal obliques, the transversus and rectus abdominis.
Discuss the pyramidalis.
- It is an insignificant muscle found in about 80% of the population.
- It is located in the rectus shealth anterior to the most inferior part of the rectus abdominus and extends from the pubic crest of the hip bone to the linea alba.
- It’s function is to draw down on the linea alba.
What are the muscles of the anterolateral abdominal wall and what are their orientations?
The outer two layers, the external and internal obliques run diagnollay and perpendicular to each other and the fibres of the deep layer of the transversus abdominis run transversely.
Where is the rectus sheath and what does it consist of?
It consists of all three anterolateral abdominal wall muscles between the midclavicular line and the midline, where they form a tough apponeurotic tendinus rectus sheath enclosing the rectus abdominis muscle.
What structures form the linea alba and where is it positioned?
- It is formed from the aponeurotic, rectus sheath as the aponeuroses interweave with left and right, superficial and intermediate, intermediate and deep layers, forming a midline raphe (seam or suture)
- It extends from the xiphoid process to the pubic symphysis.
TEST YOURSELF FIG2.6 P187.
TEST YOURSELF FIG2.6 P187.
Which two vertical muscles of the anterolateral abdominal wall are contained within the rectus sheath?
The rectus abdominis and the small pyramidalis.
What are the key features of the external oblique muscle?
- It is the larges and most superficial of the three flat anterolateral abdominal muscles.
- In contrast to the two deeper layers, the external oblique does not originate posteriorly from the thoracolumbar fascia, its posterior most fibres (the thickest part of the muscle) have a free edge where they span between is costal origin and the iliac crest.
- The fleshy part of the muscle contribute primarily to the lateral part of the abdominal wall.
- Its aponeurosis contributes to the anterior part of the wall
TEST YOURSELF 2.7 P.188
TEST YOURSELF 2.7 P.188
TEST YOURSELF 2.8 P.188
TEST YOURSELF 2.8 P.188
TEST YOURSELF 2.9 P.190
TEST YOURSELF 2.9 P.190
What is the alignment of the transversus abdominis muscles and what specifically does this make them ideal for?
They are oriented in a transverse, circumferential orientation and ideal for increasing intra-abdominal pressure.
Where is the neurovascular plane of the anterolateral abdominal wall located and what does it contain?
It is located between the middle and deepest layers of muscle, the internal oblique and transversus abdominis muscles and contains the nerves and arteries that supply the anterolateral abdominal wall.
Describe the rectus sheath and identify what structures it contains.
- It is a strong, incomplete fibrous compartment of the rectus abdominis and pyramidalis muscles.
- It contains the superior and inferior epigastric arteries and veins, lymphatic vessels and distal portions of the throaco-abdominal nerves.
TEST YOURSELF FIG2.10 P.293
TEST YOURSELF FIG2.10 P.293
What is the sensory distribution of T7 – T9?
The skin superior to the umbilicus
What is the sensory distribution of T10?
The skin around the umbilicus
What is the sensory distribution of T11 & T12?
The skin inferior to the umbilicus
What is the sensory distribution of L1?
The skin within the inguinal fold
What nerve supplies the distribution of T7 – T11?
The thoraco-abdominal nerves, which are the distal, abdominal parts of the anterior rami of the inferior six thoracic spinal nerves (T6-T11) and are the former inferior intercostal nerves distal to the costal margin.
What nerve supplies the distribution of T7 – T9 or T10?
The lateral (thoracic) cutaneous branches of the thoracic spinal nerves.
What nerve supplies the distribution of T12?
The subcostal nerve, the large anterior ramus of spinal nerve T12
What nerves supply the distribution of L1?
The iliohypogastric and ilio-inguinal nerves, the terminal branches of the anterior ramus of spinal nerve L1.
What are the primary blood vessels (arteries and veins) of the anterolateral abdominal wall?
- Superior epigastric vessels and branches of the musculophrenic vessels from the internal thoracic vessels
- Inferior epigastric and deep circumflex iliac vessels from the external iliac vessels
- Superficial circumflex iliac and superficial epigastric vessels from the femoral artery and greater saphenous vein, respectively
- Posterior intercostal vessels of the 11th intercostal space and the anterior branches of the subcostal vessels.
What vessel drains the skin and subcutaneous tissue of the superior abdominal wall?
The internal thoracic vein medially
What vessel drains the skin and subcutaneous tissue of the lateral abdominal wall?
To the lateral thoracic vein, a tributary of the femoral vein.
What vessel drains the skin and subcutaneous tissue of the inferior abdominal wall?
The inferior epigastric vein, a tributary of the external iliac vein.
The cutaneous veins surrounding the umbilicus anastomose with what?
The para-umbilical veins, small tributaries of the hepatic portal vein that parallel the obliterated umbilical vein (the round ligament of the liver).
What could cause the development of the thoraco-epigastric vein and what structures are involved?
It may exist or develop as a result of altered venous flow between the superficial epigastric vein (a femoral vein tributary) and the lateral thoracic vein (an axillary vein tributary).
Other than the anastomotic channel of the thoraco-epigastric vein between the superficial epigastric vein and the lateral thoracic vein, what deeper venous anastomosis may also exist or develop to afford collateral circulation during blockage of either vena cava?
A venous anastomosis between the inferior epigastric vein (an external iliac vein tributary) and the superior epigastric/internal thoracic veins (subclavian tributaries).
TEST YOURSELF FIG 2.11 P. 198
TEST YOURSELF FIG 2.11 P. 198
TEST YOURSELF FIG 2.12 P. 199
TEST YOURSELF FIG 2.12 P. 199
Superficial lymphatic vessels superior to the transumblical plane drain where?
The majority drain to the axillary lymph nodes, however a few drain tohte parasternal lymph nodes.
Superficial lymphatic vessels inferior to the transumbilical plane drain to where?
The superficial inguinal lymph nodes.
Deep lymphatic vessels accompany the deep veins of the abdominal wall and drain where?
The deep lymphatic vessles drain tohte external iliac, common iliac, right and left lumbar (caval and aortic) lymph nodes.
The internal (posterior) surface of the anterolateral abdominal wall is covered with what THREE (3) structures?
- Transversalis fascia
- A variable amount of extraperitoneal fat
- Parietal peritoneum.
- The infraumbilical surface of the anterolateral abdominal wall exhibits FIVE (5) umbilical peritoneal folds passing towards the umbilicals. What are they?
- A median umbilical fold attached to the apex of the bladder
- Two median umbilical folds that cover the medial umbilical ligaments
- Two lateral umbilical folds that cover the inferior epigastric vessels (and bleed if cut).
The depressions lateral to the umbilical folds form peritoneal fossae. What is the significance of the supravesical fossae?
It reflects form the anterior abdominal wall on to the bladder and rises and falls with filling and emptying of the bladder.
The depressions lateral to the umbilical folds form peritoneal fossae. What is the significance of the medial inguinal fossae?
It lies between the medial and the lateral umbilical folds in areas called the inguinal triangles (Hesselbach triangles), which are potential sites for the less common direct inguinal hernias.
What is the falciform ligament?
It is a sagittally oriented peritoneal reflection on the supra-umbilical part of the internal surface of the anterior abdominal wall that extends between the anterior abdominal wall and the liver.
What structures are enclosed in the falciform ligament?
The round ligament of the liver (ligamentum teres hepatis) and para-umbilical veins on the inferior free edge.
What is the significance of the round ligament?
It is a fibrous remnant of the umbilical vein, which passed from the umbilicus to the liver prenatally.
TEST YOURSELF FIG 2.13 P202
TEST YOURSELF FIG 2.13 P202
What are the major landmarks of the inguinal region?
The inguinal ligament and the iliopubic tract that extends from the ASIS to the pubic tubercle and constitute a bilaminar anterior (flexor) retinaculum of the hip joint.
What structures make up the retinaculum of the inguinal ligament?
The fibrous bands are the thickened inferolateral-most portions of the external oblique and aponeurosis and the inferior margin of the transversalis fascia.