Week 16 Anatomy - Abdomen + Large Vessels Flashcards
What are the special layers of fascia in the anterior abdominal wall?
**Below level of umbilical, superficial fascia consists of Camper’s Fascia (anteriorly) and Scarpa’s Fascia (posteriorly)
Scarpa’s Fascia is continuous with fascia lata of lower limb.
What are the 3 layers of lateral abdominal wall muscles?
External oblique
Internal oblique
Transversus abdominus
What is the origin and insertion of the external oblique muscle?
Originates from Ribs 5-12, around to linea alba, to the pubic tubercle and anterior iliac crest
Fibres run anteriorly and inferiorly
What is origin an insertion of internal oblique muscles?
Fibres run anteriorly and superiorly, from iliac crest. thoracolumbar fascia to costal cartilages of 10-12 and linea alba, and pubis bone.
What is the origin and insertion of traversus abdominus muscle?
From thoracolumbar fascia to costal cartilages of 7-12, anterior iliac crest, linea alba
What is the origin and insertion of the rectus abdominus?
From costal cartilages and xiphoid process down to pubis, with transverse bands of tendinous connective tissue, and joined on the R + L by linea alba
Describe the aponeurosis of the lateral abdominal wall muscles:
External forms an aponeurosis at the lateral margin of the rectus abdominus, which travels anteriorly to the rectus abdominus
Internal forms aponeurosis at the same margin, but splits to form an anterior and posterior aspect which encases the rectus abdominus.
Transversus abdominus does the same, but remains posterior to the rectus abdominus
What does the sum of the different aponeuroses of the abdominal wall form?
Rectus abdominus sheath
What muscle is responsible for the formation of the inguinal canal? What are the other components?
External oblique: forms the inguinal ligament by looping back on itself to form the inferior part of the canal. The transversalis fascia forms the rest of the canal.
**Internal oblique and tranversus abdominus form a hiatus with their attachments, and don’t directly contribute to the canal.
Where is the deep inguinal ring?
Deep (internal) ring:
Marks the internal opening of the inguinal canal
Found above the midpoint of the inguinal ligament (lateral to the epigastric vessels).
The ring is created by the transversalis fascia, which invaginates to form a covering of the contents of the inguinal canal.
Where is the superficial inguinal ring?
Marks the external end of the inguinal canal
Lies just superior to the pubic tubercle.
It is a triangle shaped opening, formed by the invagination of the external oblique, which forms another covering of the inguinal canal contents.
What is the difference between direct and indirect inguinal hernia?
Direct = directly though abdominal wall musculature
Indirect = through inguinal canal into scrotum
What are the fascial coverings of the spermatic cord?
- External spermatic fascia (derived from the aponeurosis of the external oblique muscle)
- Cremaster muscle and fascia – derived from the internal oblique muscle.
- Internal spermatic fascia – derived from the transversalis fascia.
What are the contents of the spermatic cord?
Blood vessels:
1. Testicular artery
2. Cremasteric artery and vein
3. Artery to vas deferens
4. Pampiniform plexus
Nerves:
1. Genital branch of the genitofemoral nerve – supplies the cremaster muscle.
2. Autonomic nerves
Other:
1. Vas deferens
2. Processes vaginalis
What are the first branches of the aorta?
The right and left coronary arteries, from the sinuses that form just above the cusps of the aortic valve.
What are the branches of the aortic arch?
- Brachiocephalic artery
- Left common carotid artery
- Left subclavian artery
What are the main functions/branches of the descending thoracic aorta?
Oesophageal arteries
Intercostal arteries
Bronchial arteries
Phrenic arteries
How does the aorta pass into the abdomen? What does the aorta get names?
Between the crura of the diaphragm (I.e. there is no hiatus in diaphragm for aorta)
Becomes abdominal aorta
What are the first branches of the abdominal aorta?
Inferior phrenic arteries
What are the 3 anterior branches of the abdominal aorta that supply the GI tract?
- Coeliac trunk
- Superior mesenteric artery
- Inferior mesenteric artery
What structures does the coeliac trunk supply?
Lower 1/3 of oesophagus
Stomach
First half of duodenum
What does the superior mesenteric artery supple?
From later part of duodenum to transverse colon
What does the inferior mesenteric artery supply?
The rest of colon from last part transverse colon to anal canal
What are the corresponding embryological origins/structures of the bowel blood supply?
Coeliac trunk –> foregut
SMA - midgut
IMA - hind gut
What are the paired lateral arteries of the abdominal aorta?
Renal arteries
Gonadal arteries
**Adrenal glands often supplied by renal arteries
Lumbar arteries
Where does the abdominal aorta end?
Where it bifurcates into the common iliac arteries
What veins combine to form the superior vena cava?
Left and right brachio-cephalic veins (left is longer as it travels across to merge
What veins combine to form the inferior vena cava?
Left and right common iliac veins
Why does the inferior vena cava not have equivalents of the coeliac trunk, SMA, IMA?
All venous blood from GI tract travels via portal vein to the liver prior to entry into the IVC just inferior to the diaphragm
What are the the muscles of the posterior abdominal wall?
Diaphragm
Psoas major
Iliacus
Quadratus lumborum
What artery supplies the liver?
Coeliac trunk (liver originates from foregut)
This gives off a common hepatic artery
Divides into R + L hepatic arteries to supply liver
How does the portal vein form?
Where the superior mesenteric vein and splenic vein merge
N.B. Inferior mesenteric vein has already merged with the splenic vein prior to joining the superior mesenteric vein
What is the porta hepatis?
AKA transverse hepatic tissue, runs inferior surface of liver and is area through which neurovascular structures run.
What structures pass through the Porta hepatis?
Common hepatic ducts
Hepatic artery proper
Portal vein
What arteries supply the stomach, running along lesser curvature?
Right and left gastric arteries
What arteries supply the stomach, running along greater curvature of stomach?
Right and left gastro-omental arteries
What are the three branches of the coeliac trunk?
Left gastric artery
Splenic artery
Common hepatic artery
Where does the left gastro-omental artery originate from?
The splenic artery
Where does the right gastro-omental artery originate from?
Gastro-duodenal artery (which is a branch of the common hepatic artery)
Where does the right gastric artery originate from?
From hepatic artery proper
What marks the endpoint of the foregut?
Where CBD passes into duodenum via sphincter of oddi
Describe blood supply to the duodenum:
First past via coeliac trunk: branch of the common hepatic artery, the gastro-duodenal artery.
Second part (post the duodenal papillar/sphincter of Oddi): inferior pancreaticoduodenal artery, branch of SMA.
What is the blood supply to the jejunum and ileum?
Via superior mesenteric artery, it travels inferiorly into the mesentery, and divides into many branches, forming arterial arcades that traverse the length of the small bowel, sending off vasa recta to the bowel walls to supply.
Where does the midgut end?
2/3 of the way down the transverse colon
**Midgut includes caecum, appendix, ascending colon and 2/3 transverse colon
What supplies the ileum + first part of large bowel?
Ileocolic artery –> ileum and proximal ascending colon
Right colic artery –> to ascending colon
Middle colic artery –> to transverse colon
What are the major branches of the IMA?
Left colic artery
Sigmoid arteries
Superior rectal artery
How can the duodenum be divided?
Four parts, D1, D2, D3, D4.
Forms a ‘C’ shape, with superior, descending, inferior, and ascending aspects.
What spinal levels does the duodenum typically exists?
L1-L3
What are the relations of the D1 part of duodenum?
D1 ascends upwards from pylorus, connected to liver by hepatoduodenal ligament
What is the most common site of ulceration?
D1
Which parts of the duodenum are intra vs retro-peritoneal?
First 2 cm have a mesentery and are intraperitoneal, (ampulla )
What are the relations of D2 part of the duodenum?
Curves inferiorly around the head of pancreas, anterior to R kidney, and contains major duodenal papilla (pancreatic and hepatic secretions entering the ampulla of Vater)
What are the relations of the D3 part of duodenum?
Horizontal/inferior part of duodenum, travels across to the left, crossing anteriorly to aorta and IVC, superiorly to SMA and SMV.
What are the relations of D4 part of duodenum?
Ascending aspect of duodenum, joins the Jejunum at at duodenojejunal flexure, supported by suspensory muscle of duodenum
What are the porto-systemic anastomoses?
Oesophageal
Rectal
Retroperitoneal
Paraumbilical
What is the broad ligament made out of, and what does it do?
Double fold of peritoneum that extends from sides of uterus to lateral walls and floor of pelvis
What is the round ligament?
The round ligament is a remnant of the embryonic gubernaculum.
It originates at the uterine horns (the points at which the fallopian tubes enter the uterus), and attaches to the labia majora, passing through the inguinal canal. (akin to the spermatic cord)
What are the ligaments associated with the cervix?
- Cardinal/Transverse: to lateral walls of pelvis
- Uterosacral: from cervix to middle of sacrum
- Pubocervical: connects to pubis anteriorly
What are the 2 main ligaments of the ovary, and what they do?
Ovarian ligament: attaches from broad ligament down to ovary
Suspensory ligament: extends outwards from the ovary to the lateral abdominal wall. I\The function of this ligament is to contain the ovarian vessels and nerves
Describe relations of the prostate:
Base = neck of bladder
Apex = fascia of deep perineal muscles and urethral sphincter
Anterior = retropubic space, fat occupying space behind pubic symphysis
Posterior = ampulla of rectum
How can the male urethra be characterised?
Pre-prostatic
Prostatic
Membranous
Spongy
What vertebral levels are the kidneys generally found?
T12-L3 (a little lower on the right due to the liver)
What muscles are the kidney resting on?
Psoas
Quadratus lumborum
What are the relations of the right kidney?
Hepatic flexure, duodenum, liver anteriorly, and superiorly
What are the relations of the left kidney anteriorly?
Stomach, spleen, descending colon, pancreas
What is blood supply to and venous drainage from the kidneys?
Renal arteries directly from lateral aspects of aorta (L renal vein directly inferior to SMA)
Renal veins from kidney hilum directly into IVC
What is the macroscopic features of the kidney anatomy?
Cortex on the outside
Medullary pyramids on the inside
Tips of medullary pyramids are minor calyces
These drain into major calyces
Renal pelvis is where all urine drains into, prior to passing into ureters
What is the origin of the ureter?
Pelvico-ureteric junction (PUJ)
What is the basic course of the ureters and relations?
Commencing from hilum of kidneys, ureters run retroperitoneal along the psoas major muscle
Gonadal arteries pass anteriorly over the ureters as they pass inferiorly.
Ureters pass anteriorly/cross over common iliac artery and vein as they cross into the pelvic rim and posteriorly into pelvis.
Ureters terminate by passing obliquely into bladder at vesico-ureteric junction (VUJ) at the bladder trigone.
What are the basic relations of the bladder? Where is it located when it is empty?
Rectum posteriorly
Pubis antero-inferiorly
Covered superiorly by peritoneum
Usually resides within lesser pelvis when empty, but expands superiorly when filling
What is the purpose of the internal urethral sphincter in males?
Autonomic control, contracts during ejaculation to prevent retrograde ejaculation
What innervates the external urethral sphincter?
Pudendal nerve
What is the blood supply to the bladder?
Internal iliac arteries
Internal iliac veins
What is the innervation of the bladder
Sympathetic fibres from inferior thoracic and upper lumbar spinal cord levels
Sympathetic fibres from from sacral spine via splanchnic nerves
What autonomic system is responsible for erection and ejaculation?
P = point = parasympathetic for erection
S = shoot = sympathetic for ejaculation
