Gross anatomy of GI 2 Flashcards
How is the gut tube held in the abdominal wall
Suspended by peritoneum in embryo
Attached along it length to the posterior abdominal wall via dorsal mesentery
Foregut attached to the anterior abdominal wall by ventral mesentery
What are the derivatives of gut tube
oesophagus stomach small intestine large intestine rectum and anal canal accessory organs
What is the transpyloric plane
Lower border of L1 vertebrae
Parts of the stomach
Fundus
Body
pyloric antrum
Pyloric canal
What is the lesser omentum
Derived from ventral mesentery
Lesser curvature
subdivides into Hepatogastric lig. and Hepatoduodenal lig.
Has foregut arteries, portal vein and bile duct
What is greater omentum
Peritoneal reflection derived from dorsal mesentery
Greater curvature
4 parts of the duodenum
Superior
Descending
Inferior
Ascending
Which parts of the duodenum are retroperitoneal
1st part is intraperitoneal
Rest are retroperitoneal
What does the 2nd part of the duodenum contain
major duodenal papilla and minor duodenal papilla
Major duodenal papilla marks boundary between foregut and midgut
What are the jejunum and ileum of small intestine
Intraperitoneal parts of the SI
Suspended by mesentery
Jejunum is the proximal 2/5 while ileum is the distal 3/5
Derived from the midgut
What connects the SI and LI
Ileocaecal junction
What is anal canal lined with
Upper part lined by mucosa similar to rectum
-has longitudinal folds = anal columns
-Form a circle around the anal canal called the pectinate line
-Inferior to this is an area called the anal
pectan
-This then ends at the anocutaneous
What type of muscles are the anal sphincters made from
Internal anal sphincter
- smooth muscle
External anal sphincter
- skeletal muscle (deep, superficial and subcutaneous)
What is the pelvic floor
Separates the pelvic cavity from the perineum below
Formed by muscle and fascia
Supports pelvic viscera and maintains closure of rectum and vagina
What does the levator ani consist of
iliococcygeus Pubococcygeus Puborectalis Urogenital hiatus anteriorly Posteriorly forms anococcygeal ligament Anal aperture posteriorly
What is the perineal membrane
perineal membrane is a thick, triangular-shaped fascial sheet that fills the space between the pubic arches
Pelvic floor is supported anteriorly by perineal membrane
It has free posterior border
Contains the urethral hiatus and vaginal hiatus
What is a deep perineal pouch
Deep perineal pouch is a narrow region superior to perineal membrane
Contains skeletal muscles
Act as sphincters for vaginal and urethral openings
Stabilise posterior edge perineal membrane
What is the perineum (anatomically)
Diamond shaped structure
Subdivided by a theoretical transverse line drawn between the ischial tuberosities
-Anterior urogenital triangle
-Posterior anal triangle
What does the anal triangle contain
Anal aperture
External anal sphincter
Ischioanal fossae (x2)
What does the urogenital triangle contain
Urethral and vaginal openings
has perineal membrane - associated with a deep and superficial pouch
Roots of external genitalia
What is the Perineal body
Fibrous connective tissue structure
Muscles of the pelvic floor and perineum attach to it
Positioned in the midline of the posterior border of the perineal membrane
Posterior end of urogenital hiatus formed by levator ani connect to it
Midway between ischial tuberosities and between the urogenital and anal triangles
What are the specific blood supplies of each gut tube
Foregut - celiac artery
Midgut - superior mesenteric artery
Hindgut - inferior mesenteric artery
What does foregut form
How does it form this
Stomach it rotates 90 degrees clockwise left wall grows faster giving the greater curvature Ventral mesentery dragged to the right dorsal mesentery moves to the left
How is the greater omentum formed
Growth of mesentery on the greater curvature of the stomach in an inferior direction creates the greater omentum
hangs down and covers the small intestines
Initially 4 layers of peritoneum but posterior layer fuses with the mesentery of transverse colon
