Gastrointestinal Tract Flashcards
(47 cards)
What are the layers that we encounter as you go down the skin through the anterior abdominal wall?
Skin, superficial fascia, the three abdominal muscles (external, internal and transversalus) then the transversalis fascia, extraperitoneal fascia and finally the parietal peritoneum.
What is the body framework of the abdomen? Where are the borders and where do muscles attach to?
Costal margin at the superior end, iliac crest with the ASAS (anterior superiorly), pubic tubercle (lump of bond at the lateral end of the pubic crest) and pubic crest.
The outermost layer of muscles will overly the anterior costal margin area.
The middle layer of muscles will attach directly to the edge of the costal margin.
The most posterior layer will have to attach behind the costal margin. It will also be in the same plane as the diaphragm.
What happens to the three layers of abdominal muscles as it moves medially towards the mid line?
It is fleshy laterally and becomes aponeurotic medially. Until it meets at the midline forming the linea alba.
Where are the external oblique muscles found, direction of fibres, origin and attachments and how it folds at the lower end of attachment?
This is the outermost layer of muscle with front pocket directions. The origin and attachment is found on to be overlying on the thoracic cage and it moves up towards the serratus anterior and pectoralis major. The EO will attach to the anterior half of the iliac crest as it moves down, once it gets to the ASAS it will jump and attach to the pubic crest. Also forms aponeuroses as it moves medially to the mid line.
This forms a free inferior margin.
What is the inguinal ligament?
The free inferior margin of the external oblique is thickened a lot and folds onto itself.
Where are the internal oblique muscles found, direction of fibres, origin and attachments and how it folds at the lower end of attachment?
It attaches directly to the superior aspect of the costal margin and meets back in the mid line linea alba and posteriorly as far back as the thoracolumbar fascia. The muscle will then attach to the ASAS. From there the lower most fibres of the internal oblique muscles originate from the lateral 2/3 of the inguinal ligament. The fibres at the lower end are arching upper then lower down to attach to the pubic crest.
It is back pocket direct of muscle fibres.
Where are the transversus abdominus found, direction of fibres, origin and attachments and how it folds at the lower end of attachment?
This is the deepest layer that underlies the posterior end of the costal margin in the same plane as the diaphragm. It will continue as far posteriorly as the thoracolumbar fascia and meet in mid line. The lower most fibres originate from the lateral 1/3 of the inguinal ligament then arches to be inserted into the pubic crest too.
What happens at the pubic crest when both the internal oblique and transversus abdominus attach to the pubic crest?
This forms a conjoined tendon with the two fibres fusing.
Where are the rectus abdominus found, direction of fibres, origin and attachments and how it folds at the lower end of attachment?
This is found in the midline and arises inferiorly from the pubic crest. The muscle ascends up the midline while diverging. It will cross pass the costal margin (5,6,7) and attach right under the pectoralis major.
Tendinous inscriptions are disruptions found along the rectus abdominus to make the muscle fibres shorter and therefore stronger.
What is the rectus sheath and what forms it?
The rectus sheath is made up of the three different aponeuroses from the three different abdominal muscles. The sheath encloses the rectus abdominus. Some areas there is also the presence of a posterior sheath behind the rectus abdominus.
What is the arcuate line in the anterior abdominal wall?
The arcuate line is where the aponeuroses end and arches for the posterior.
How is the rectus sheath organised around the rectus abdominus with respect to the upper and lower portions?
The upper rectus sheath will have the aponeuroses split evenly about 1.5 each around the rectus abdominus. Whereas lower down on the sheath (one inch below the umbilicus it is positioned completely in front of the rectus abdominis.
- The rectus abdominis sits directly on top of the transversalis fascia.
What is the neurovascular supply to the anterior abdomen like?
It is in the same plane as the thoracic neurovascular supplies. The supplies are found between the internal oblique and the transversalis abdominis. There will be segmental innervation of the anterior abdominal wall from T10 (umbulicus) to L1 (groin)
Where does the main arterial supply come from for the anterior abdomen wall?
The main supplies are the superior epigastric and the inferior epigastric that run in the rectus sheath (posterior part of the sheath).
Internal thoracic artery branches out to superior epigrastic. Inferior epigastric is a branch of the external iliac artery.
What is the venous system like in the abdomen wall?
There is a dual venous drainage system, the portal venous drainage and the systemic venous drainage.
What is the pectineal ligament?
This is a ligament that lines the pubic bone and marks the pelvic inlet.
What is the lacunar ligament?
This is a crescentic extenion between the inguinal and pectineal ligament that forms.
Where are the testes developed in and where must they move to?
Testes develop in the posterior abdominal wall in the extraperitoneal fat. They need to descend into the scrotum.
That is a move from extraperitoneal fat, transversalis fascia, transversus abdominus, internal and external oblique muscles efore you get to the superficial fascia on the skin.
What is the pathway of the testes to the scrotum like?
The hole created by the testes in the fascia transversalis is found half way between the ASAS and the pubic tubercle about a finger’s breadth above the linguinal ligament. This is called the deep inguinal ring.
There are arching borders from the TA and IOM (internal oblique muscles) that coem from the lateral ends of the inguinal ligaments forming space. The testes will turn medially with the arching roof formed from the fibres forming the conjoined tendons. This is called the inguinal canal.
There is a triangular hole at the end of the external oblique called the superficial inguinal rings.
What are the features of the inguinal canal?
How is the spermatic cord formed by having addition layers added to the testes?
Spermatic cord is made up of all the following as it passes through the layers. The first layer is picked up from when it passes the transversalis fascia.
The second to be picked up is the cremasteric fascia (responsible for testicular contraction because of some muscle there). This is coated as it passes the inguinal canal and particularly by the internal oblique muscle.
The external spermatic fascia is obtained by passes through the external oblique.
At this point you can technically call it the spermatic cord.
When is an abdominal hernia?
This is when abdominal content protrudes through an abdominal wall because of the increase pressure in the abdomen and pushes on weakened areas.
What is the bilateral indirect inguinal hernia?
This is a protrusion through the deep ring into the inguinal canal then follows the same path as the testes.
The indirect hernia arises from incomplete closure of the processus vaginalis, hence the herniated peritoneal contents extend into the scrotum (or labia).
What is bilateral direct inguinal hernia?
A protrusion forwards into the inguinal canal through an area of weakness in its posterior wall.
The inguinal triangle is particularly weak area in the anterior wall.
