Week 1 - Abdomen Flashcards
What anatomical landmarks are used to divide the abdomen into quadrants and regions?
Quadrants
- transumbilical plane (level of L3/4 disc)
- median plane
Nine regions
Horizontal
- subcostal plane -> inferior borders of 10th costal cartilages
- transtubercular plane -> iliac tubercles (level of L5)
Vertical
- 2 x midclavicular plane -> midpoint of clavicles to mid-inguinal points
Discuss the possible locations at which a pre-synaptic parasympathetic neuron can synapse with a post-synaptic parasympathetic neuron.
Synpase within terminal ganglia (located near or within target organ)
Describe the foetal formation of the mouth and anus. In what week is this process completed?
- Endoderm fuses with ectoderm at the head and tail of the embryo
- Head - formation of oral membrane
- Tail - cloacal membrane
- These membranes break through the surface
- By week 8, the GI tract is a continous tube extending from the mouth to the anus
- It is open to the external environment at each end
What is the portal circulation? How does it relate to the organs of the abdomen and the IVC?
- Special part of circulation that supplies the digestive system
- Nutrients broken down by stomach enter portal circulation
- then, delivered to liver for absorption and packaging
- blood travels via hepatic veins
- then, blood enters inferior vena cava
- Portal vein = spenic vein and superior mesenteric vein
List the organs found in each of the four quadrants
What are the key differences between the abdominopelvic splanchnic nerves and the pelvic splanchnic nerves?
- Abdominopelvic
- SNS
- Supplies abdominopelvic viscera
- T5-L3
- Fight or flight function
- Pelvic Splanchnic
- PNS
- Supplies viscera not supplied by Vagus Nerve (CNX)
- S2-S4
- Rest and digest function
Outline the attachments, nerve supply and actions of the External Oblique mm
Origin - external surfaces of ribs 5-12
Insertion - Linea alba, pubic tubercle, anterior 1/2 of iliac crest
Nerve supply - thoracoabdominal nerve and subcostal nerves
Action - flexion and trunk rotation; compression of viscera
Define the greater omentum
4-layered fold of peritoneum that hangs down like an apron
Define mesentery
Double layer of peritoneum, continuous with parietal and visceral peritoneum. It anchors organ to the posterior abdominal wall
Describe the difference between an intraperitoneal and an extraperitoneal (retroperitoneal) organ
Intraperitoneal organs - almost completely covered with visceral peritoneum e.g. stomach
Extraperitoneal organs - only partially covered with peritoneum, usually one surface e.g. kidneys
Outline the attachments, nerve supply and actions of the Rectus Abdominis mm
Origin - pubic symphysis and crest
Insertion - xiphoid process and costal cartilages 5-7
Nerve Supply - thoracoabdominal nerves
Action - flexes trunk; compresses and supports viscera
In relation to GI tract development, how does the purpose of lateral folding differ to the purpose of head and tail folding?
- Head to tail folds appear after lateral folding
- these folds establish the foregut, midgut and hindgut
- Lateral folding establishes the formation of the GIT
List the embryological events that occur at: 17 days, 20 days, 22 days and 4 weeks
- Day 17 - Gastrulation, where two layered embryo becomes a three layered embryo (monte carlo biscuit!)
- Day 20 - Formation of neural tube (ectoderm begins folding, which later becomes spinal cord; Differentiation of mesoderm into somite (e.g. dermatome, myotome, sclerotome) intermediate and lateral mesoderm (splanchnic, somatic mesoderm)
- Day 22 - Undercutting begins, where there is lateral folding to form primitive gut
- 4 weeks - Undercutting is complete; formation of mouth and anus begins (this is later completed by week 8, when the endoderm and ectoderm fuse)
List the nerves that make up the abdominopelvic splanchnic nerves
- Greater splanchnic (T5-T9/10)
- Lesser splanchnic (T9-T10/11)
- Least splanchnic (T12)
- Lumbar splanchnic (L1-L3)
These supply the abdominal viscera
Describe the function of visceral afferent fibres (provide some examples of the type of information conveyed by these fibres)
Provide information about the body’s internal environment (e.g. sensitive to sudden distension, spasms, chemical irritants, mechanical stimulation)