Lecture 20 And 21: Gastrointestinal Tract Flashcards
What are the adult midgut derivatives?
What blood vessel supplies it?
- most of the duodenum
- jejenum
- ileum
- caecum
- appendix
- ascending colon
- right half of transverse colon
Supplied by superior mesenteric artery branches
What are the adult foregut derivatives slide 6
-pharynx, tongue, tonsils, salivary glands, oesophagus, stomach, duodenum, liver, gallbladder, bile, duct system and pancreas
What are the adult hindgut derivatives slide 8
Supplied by inferior mesenteric artery branches
- distal portion of transverse colon
- sigmoid colon
- rectum
- anal canal
- epithelium of urinary bladder
- most of urethra
Localisation of pain and embryological origin
Pain arising from the foregut derivatives localises in the _____region.
Pain arising from midgut localises in the _____region
Pain arising from hindgut derivatives localises in the _____region
Localisation of pain and embryological origin
Pain arising from the foregut derivatives localises in the __(epigastric)___region.
Pain arising from midgut localises in the __(periumbilical)___region
Pain arising from hindgut derivatives localises in the __(hypo gastric )___region
The proximal opening of the GIT. Label diagram on slide 9
H
The muscles of mastication drives the mandible to open and close the proximal opening of the GIT. What are these muscles?
What is their innervation?
Masseter
Temporalis
Lateral pterygoid
Medial pterygoid
Innervated by mandibular branch of trigeminal nerve (CN V3)
What is the origin, insertion, action of these muscles?
Masseter:
ORIGIN: Zygomatic bone and arch (the anterior two thirds)
INSERTION: Lateral surface of the ramus and angle of the mandible
ACTION: Elevation, adduction and protrusion of the mandible
TEMPORALIS:
ORIGIN: Fossa temporalis and the temporal fascia
INSERTION: Coronoid process of the mandible and the anterior surface of the ramus of the mandible
ACTION: Vertical part: elevation of the mandible; Horizontal part: retraction of the mandible; chewing
Lateral pterygoid:
ORIGIN: Superior head: the greater wing of the sphenoid; Inferior head: the lateral surface of the lateral pterygoid plate
INSERTION: Superior head: the capsule and articular disc of the temporomandibular joint; Inferior head: the mandible
ACTION: Protraction of the mandible and aids in mastication
Medial pterygoid:
ORIGIN: Medial surface of the lateral pterygoid plate; the palatine bone; the tuberosity of the maxilla
INSERTION: Medial surface of the angla and ramus of the mandible
ACTION: Protraction and elevation of the mandible
Tell me stuff about the temperomandibular joint?
- modified hinge-type synovial joint
- articular disc
- anterior to external acoustic meatus
- condyloid and coronoid processes of mandible
- mandibular fossa in the zygomatic process of temporal bone
Tongue
What are the intrinsic muscles innervated by?
Extrinsic muscles alter position of tongue? What innervates them?
What are the intrinsic muscles innervated by? Hypoglossal nerve
Extrinsic muscles alter position of tongue? What innervates them? All are innervated by hypoglossal except for one muscle which is the palatoglossus innervated by vagus
Innervation of the tongue (5 cranial nerves involved)
Sensory
Mandibular (from trigeminal) via lingual nerve Facia via chords tympani Glossopharyngeal Vagus Hypoglossal Slide 9 gotsta see it
Swallowing (deglutition)
Food bolus➡ mouth➡ pharynx➡ oesophagus➡ stomach
Oral phase (voluntary: somatic motor)
-CN V3 (tensor veli palatini muscle), CN X and CNXII)
Chew and then styloglossus (CN XII) and palatoglossus (CN X) muscles raise the tongue:
1- to push the bolus back to the oropharynx
2- to raise the uvula
Pharyngeal phase (involuntary and rapid)
Reflex (CN IX, CN X: motor)
Constrictor muscles: superior, middle and inferior (pharynx widens and shortens.
Levator veli palatinin (soft palate elevated)
Elevate the hyoid bone and larynx, move the epiglottis to close off the trachea
Oesophageal phase (involuntary) (CN X: motor) -sequential contraction of all 3 pharyngeal constrictor muscles forces food bolus inferiorly into the oesophagus
Muscle of soft palate
Slide 21
Study shit out of it
Label diagram of pharynx slide 22
Yep
Pharyngeal constrictors
Contract wall of pharynx sequentially from superior to inferior to move food bolus from oropharynx to oesophagus.
All insert into the median rapid of pharynx
-inferior constrictor is most superficial and contracts last.
-motor innervation from vagus nerve
Find picture in colour atlas
Tell me some info about the oesophagus How long? Crosses diaphragm at what level Innervation? Blood supply?
-25 cm long (pharynx➡ stomach) 2cm diameter
-thorax➡ abdomen via oesophageal hiatus in diaphragm at T10 vertebral level.
-circular and external longitudinal layers
-superior: external longitudinal under voluntary control (striated muscle)
-middle: striated + smooth
-inferior: smooth muscle (involuntary, under ANS control)
-innervation: recurrent laryngeal (somatic), Vagal trunks + greater splanchnic nerves (smooth)
Blood supply: left gastric blood vessels
Superior portion of oesophagus: motor innervation from recurrent laryngeal nerve
Inferior portion of oesophagus: smooth muscle innervated by vagus and sympathetic fibres
Stomach
What level does oesophagus turn into stomach?
Has 4 parts, what are they?
2 curvatures:
Cardial orifice: opening of oesophagus into stomach at vertebra T11 level.
4 parts: cardia, fundus, body, pylorus
2 curvatures: lesser and greater curvatures
Contracted state: gastric mucosa thrown into longitudinal folds (rugae)
Function: to accumulate ingested food and mechanically and enzymatic ally prepare it for digestion
What is the stomachs ANS innervation?
Visceral afferent refers pain to?
Blood supply?
Venous drainage?
What is the stomachs ANS innervation? Parasympathetic via vagus; sympathetic from T6-T9 via greater splanchnic nerves
Visceral afferent refers pain to? Epigastric region
Blood supply? Left and right gastric arteries (from coeliac trunk)
Venous drainage? Gastric➡ portal vein
Label the diagram on slide 29
Fun cardiac body pile
Yep
There are three layers of the stomach called tunica muscularis. Name them all and what layer they lie in
Oblique: inner layer
Circular: middle layer
Longitudinal: external layer
SlIde 30
What is the function of the gastric mucosa?
What is the function of the gastric folds (rugae)?
Don’t know possum pie, you’ll have to find out
Duodenum
25cm long
- largely retroperitoneal
- descending part cradles head of pancreas and receives hepatopancreatic ampulla.
- inferior part crosses posteriorly to superior mesenteric blood vessels at L3 level.
Jejenum
ileum
- 5m long
- suspended by mesentery
- occupies left upper quadrant of abdomen
- larger in diameter
- thicker walls
- less fat in its mesentery
- arterial branches with fewer arcades and longer vasa recta
- internally it has mucosal folds that are higher and more numerous
Ileum:
- 3.5m long
- suspended by mesentery
- jejenum ➡ caecum
- only part of small intestine to have peyers patches
Mesentery slide 36
Fan-shaped fold of peritoneum that attaches jejenum and ileum to posterior abdominal wall.
- directed inferiorly and obliquely from duodenojejunal junction towards the right SI joint
- BV, lymph nodes and nerves sandwiched between 2 layers of peritoneum
What are the vessels of the small intestine
Slide 36- find the picture dum head didn’t labell dem
Ileocecal junction
-Junction of small and large intestines in right iliac fossa
-ileocaecal valve passively permits one-way movement of chyme from ileum➡ caecum
Caecum: part of ascending colon inferior to ileocaecal junction
Slide 38
Appendix slide 39
7-10cm long
- retro-caecal in majority of people
- contains lymphoid tissue
- suspended by mesoappendix
- non-essential (vestigial organ)
Tell me about appendicitis
Common cause of abdominal pain
Causes in people:
Young: hyperplasia of lymphoid tissue
Older: obstruction by faecal matter
Appendicitis will first present with vague pain in the umbilical region= dermatome of T10 (visceral afferent pain fibres travelling retrograde with sympathetic fibres).
Once the inflammation spreads to the peritoneum then you will get the sharp pain in the right lower quadrant, particularly over McBurney’s point.
McBurney’s point
1/3 along oblique line from ASIS to umbilicus
-palpation of McBurney’s point will cause maximum pain for patients with appendicitis.
-will also experience extrem localised pain on release of hand “rebound tenderness”
Slide 41
