Understanding the peritoneal cavity Flashcards
What is the gastrula?
the stage following the blastula. Embryo develops 3 layers: ecto-, meso- and endoderm
In the developing embryo, what does the endoderm, mesoderm and ectoderm go on to form?
Endoderm - majority of gut, including most of epithelium and glands of digestive tract
Mesoderm - muscular layers
Ectoderm - epithelium at extremities of tract (cranial and caudal)
Label the 3 layers of the gastrula in the developing fetus
How is the primitive gut formed?
•Formed as a result of two folds:
Cranial-caudal (head to tail)
Lateral (side to side)
At 4 weeks the cranial and caudal ends are still closed by which 2 membranes?
Bucco-pharyngeal
Cloacal
Which contents make up the foregut, midgut and hindgut?
FOREGUT -
Oesophagus
Stomach
Proximal half Duodenum
Liver
Pancreas
MIDGUT - Distal half duodenum, Jejunum, Ileum, Cecum, Ascending & ¾ Transverse Colon
HINDGUT - ¼ Transverse, Descending & Sigmoid Colon, & rectum
Label the forgut, midgut and hindgut
How is the primitive gut held in place?
•Held in position by mesenteries (a structure of mesodermal origin)
What is mesentry formed by?
Mesentery – formed by a double layer of peritoneum
What are the 2 types of mesentry?
Mesentery – dorsal or ventral according to its relative position with respect to gut tube
Complete the diagam of the primitive gut
What is the role of the mesentry?
- Suspends gut organs
- Pathway for blood, innervation & lymphatics to reach the gut
_________ mesentery degenerates during development, except for ________
Ventral
Foregut
How does gut rotation anomaly occur?
- Duodenum constriction
- Midgut volvulus, leading to ischaemia, necrosis or possibly death
What are the symptoms of gut rotation anomaly?
- Vomiting
- Pain
- Abdominal distention
What does the dorsal mesentry attach?
Attaches gut organs to posterior abdominal wall (‘back’)
What does the dorsal mesentery give rise too?
Gastrosplenic ligament
Lienorenal ligament
Greater omentum
Mesentery of small & large intestine
What does the ventral mesentery give rise to?
(foregut only)
Ligaments around the liver
Falciform ligament
Lesser omentum
Where is the lesser omentum situated?
- Attaches lesser curvature stomach to back of liver
- Has a free edge
Complete the diagram of the anatomical regions
What is the superior border of the abdomen?
Diaphragm
What is the abdominal cavity also known as?
•Abdominal cavity occasionally called Abdominopelvic
(Abdomen proper + greater pelvis)
Which anatomical structure is continuous with the lesser pelvis?
Greater pelvis
Complete the diagram
What makes up the external abdominal wall?
- Flat abdominal muscles
- Lumbar vertebral column
Which muscles make up the anterior abdominal wall?
External oblique
Internal oblique
Transversus abdominis
Rectus abdominis
External oblique
To
From
From: outer surface of lower eight ribs
To: linea alba
iliac crest
pubic tubercle
Internal oblique
From
To
From: lat 1/3 inguinal ligament
ant 2/3 of iliac crest
To: linea alba
costal margin
crest of pubic bone
Transversus abdominis
From
To
From: lat 1/3 inguinal ligament
int surf lower 6 ribs
iliac crest
To: linea alba
crest of pubic bone
Rectus abdominis
From
To
From: pubic symphysis + crest
To: xyphoid process
5th-7th costal cartilages
Which muscle is this?
Internal oblique
Which muscle is this?
External oblique
Which muscle is this?
Transversus abdominis
Which muscle is this?
Rectus abdominis
What is the blood supply / drainage of the muscles of the anterior abdominal wall?
Arteries: Sup and Inf epigastric, intercostal, circumflex iliac
Veins: thoracoepigastric
(between lat thoracic and Sup epigastric)
What is the innervation of the muscles of the anterior abdominal wall?
Thoracoabdominal nerves (also thoracic and subcostal nerves for rectus abdominis)
What is the function of each muscle of the anterior abdominal wall?
Ext Obl: work with Int Obl for torsional movement of trunk
Int Obl: flex and rotate trunk; compress viscera
Transv Abd: compress and support viscera
Rectus Abd: flexes trunk; compress viscera
Complete the diagram
Complete the diagram
Which ligament is this?
Falciform ligament
Locate the lesser omentum
How are the lesser/greater sacs formed?
•Formed as a result of organ rotation
Where are the greater/lesser sacs located?
- Lesser sac behind stomach
- Rest of peritoneal cavity – greater sac
How do the greater/lesser sacs communicate?
• Communicate via the epiploic foramen (of Winslow)
What is the light grey and dark grey arrows pointing at?
Light grey - lesser sac
Dark grey - Free edge of the lesser omentum
What is the purpose of the inguinal canal?
•The inguinal canal serves as a passageway for the
- spermatic cord to reach the scrotum in the male
- the round ligament of the uterus to reach the labia majora in the female
What is the inguinal canal limited by?
•Limited by the superficial and deep inguinal rings (DR)
Which structures travel through the inguinal canal in both genders?
For both genders the genital nerve (a branch from the genitofemoral) and other blood and lymphatic vessels also travel through this canal
Which gender has a larger inguinal canal?
Males
What does the spermatic cord consist of?
vas deferens, gonadal vessels, nerves, lymphatics and the cremaster muscle.
As the spermatic cord passes through the abdominal wall it takes a sleeve or covering from with 3 layers?
- transversalis fascia => contributes the innermost covering of the spermatic cord – the internal spermatic fascia
- internal oblique => contributes the middle covering layer to the cord –
the cremasteric fascia
- the external oblique => contributes the outer covering of the cord –
the external spermatic fascia
Complete the diagram
Complete the diagram
