Gastrointestinal Tract Flashcards
(36 cards)
Roughly define where the abdomen is situated.
Between the thorax and the pelvis.
Which four structures provide attachment points for the anterior abdominal wall muscles?
The iliac crest, the anterior superior iliac spine (ASIS), the pubic tubercle and the pubic crest.
How many flat and vertical muscles are there in the anterior of the abdomen?
3 flat muscles.
2 vertical muscles (paired).
The external oblique muscle, internal oblique muscle and transversus abdominus muscle have distinguishable lateral and medial components. Explain.
The EO, IO and TA muscles are fleshy laterally and aponeurosis medially. The aponeurosis of each interdigitate to form the linea alba at the midline.
What is the fiber direction of the external oblique muscle?
Inferomedial “front pocket” (forwards, downwards).
Describe the attachment points of the external oblique muscles.
Superiorly, the EO muscle attaches to the ribs, overlapping the costal margin.
Medially, the EO muscle attaches to the linea alba.
Inferiorly, the EO muscle attaches to the iliac crest posteriorly, then laterally, then to the ASIS, before jumping and attaching to the pubic crest and pubic tubercle. (i.e. central part has no attachments).
Posteriorly, the EO muscle is associated with posterior abdominal wall muscles.
Describe the attachment points of the internal oblique muscle.
Superiorly, the IO muscle attaches to the costal margin.
Inferiorly, the IO muscle arises from the lateral part of the inguinal ligament (2/3) before arching up and down to insert into the pubic crest via a conjoint tendon.
Posteriorly, the IO muscle is associated with posterior abdominal wall muscles.
What is the fiber direction of the internal oblique muscle?
The majority of the IO muscle has superomedial direction (upwards and medial). However, the lowermost fibers do not. They arch up, over and downward to insert into the pubic crest.
Define and describe the inguinal ligament.
The inguinal ligament is the free, inferior border of the external oblique muscle. It is an undercurving, thickened, fibrous band that extends from the anterior superior iliac spine (ASIS) to the pubic tubercle.
Describe the attachment points of the transversus abdominus.
Superiorly, the TA muscle attaches to the costal margin.
The lowermost fibers arise from the lateral part (1/3) of the inguinal ligament and arch up and down to insert into the pubic crest via a conjoint tendon.
Posteriorly, the TA muscle is associated with posterior abdominal muscles.
Describe the fiber direction of the transversus abdominis muscle.
The majority of the TA muscle has transverse (horizontal) fiber direction. However, the lowermost fibers do not. They arch up, over and downward to insert into the pubic crest.
What are the two vertically orientated muscles of the anterior abdominal wall?
The rectus abdominis muscles and the pyramidalis muscles.
Briefly discuss the pyramidalis muscles of the anterior abdominal wall.
The pyramidalis muscles are very small muscles (not present in everyone) which attach to the pubic crest. The muscles do not have a major role.
Discuss the location, features and covering of the rectus abdominus muscles.
The rectus abdominus muscles are paired muscles situated on either side of the linea alba. They are the principle vertical muscles of the anterior abdominal wall. The rectus abdominus muscles arise from the pubic bones and attach to the rib cage. The muscles are intersected by tendons. The rectus abdominus muscles are enclosed in the rectus sheath (an envelope of fascia).
What is the rectus sheath formed by? What does the rectus sheath enclose?
The rectus sheath is formed by the aponeuroses of the external oblique, internal oblique and transversus abdominus muscles. The rectus sheath is a fibrous compartment that encloses the rectus abdominus muscles.
If you made a cut through the anterior abdominal wall (slightly laterally, as to avoid the linea alba), what would you see layer by layer?
Skin > superficial fascia > external oblique > internal oblique > transversus abdominus > transversalis fascia > extraperitoneal fascia (fat) > peritoneum
Where do the testes develop?
The posterior abdominal wall in layer 7 (the extraperitoneal fat).
Describe the journey of the testes as they descend to the scrotum.
The testes descend in an oblique, inferomedial manner (via the “inguinal canal”) from the extraperitoneal fat, puncture the transversalis fascia, go behind the arched fibres of the internal oblique and the transversus abdominus and leave the inguinal canal via the split of the external oblique. (The split where the EO attaches to the pubic tubercle and the pubic crest).
Discuss the two inguinal rings.
The deep (internal) inguinal ring is a circular hole in the transversalis fascia. It is roughly 1/2 way along the inguinal ligament and a fingers breadth above it.
The superficial (external) inguinal ring is a triangular split between the fibers of the external oblique aponeuroses that attach either to the pubic tubercle or the pubic crest.
The inguinal canal is more prominent in which sex?
Males.
Discuss the boundaries of the inguinal canal.
The inguinal ligament provides a “floor” for the inguinal canal.
The arched, lowermost fibers of the internal oblique and transversus abdominus provide a “roof” for the inguinal canal.
What problems may occur due to the “deficiency” created by the inguinal canal?
Inguinal hernias may occur, whereby a protrusion/passage of abdominal contents enters the inguinal canal.
Outline the bony framework of the abdominal wall.
Lumbar vertebrae 1-5 (L1-5) & associated IV discs, 12th ribs.
Name the three paired muscles you have learnt that are situation in the posterior abdominal wall.
- Psoas major (sometimes psoas minor is present)
- Quadratus lumborum
- Iliacus
