Metabolism Anatomy Flashcards
What happens to blood from the digestive system?
Collected in the hepatic portal vein then transmitted to the liver for processing before it enters the systemic circulation via the hepatic veins to the inferior vena cava
What are the boundaries of the oral cavity?
Anterior = lips Posterior = palate down to epiglottis (vertically) Roof = hard and soft palate Floor = tongue
Describe the hard palate
Made of the palatine process of the maxilla and the horizontal plate of the palatine bone
Describe the soft palate
Made of fibrous tissue with muscle fibres from the muscles that move it (levator palatine, tensor palatine and musculus uvulae)
What is the vestibule?
Space between the teeth and the cheek
What is the oral cavity proper?
Occupied mostly by the tongue
What is the frenulum?
A fold of mucosa that attaches the tongue to the mouth floor
Where does the palatine tonsil lie?
In the fossa formed between two folds of mucous membrane which project down from the soft palate (palatoglossus and palatopharygeus arches)
Where is the parotid gland located?
Occupies the triangular space made by the ramusof the mandible, the external ear and the upper SCML muscle
Where is the submandibular gland located?
In the diagastric (submandibular) triangle which takes a U shape around the posterior border of the mylohyoid muscle
Describe the sublingual gland
Group of small lands in the mouth floor either side of the tongue, they open with separate ducts on the plica sublingualis
What is the plica sublingualis?
Fold of mucous membrane between the tongue and the body of the mandible
How many teeth does an adult have?
32 permanent teeth; 2 incisors, 1 canine, 2premolars and 3 molars on each side of the jaw (x4)
How are the teeth attached to the mouth?
Via the periodontal membrane; attaches the tooth to the socket in the alveolar part of the mandible
What is the auriculo-temporal nerve?
Branch of the mandibular nerve (V3) which carries sensory and secreto-motor fibres to the parotid gland
Describe the nerve supply to the parotid gland
Supplied by the auriculo-temporal nerve (branch of V3) which has sensory fibres that are supplied via V3 and parasympathetic secreto-motor fibres that are supplied by the glossopharyngeal nerve (CN IX) through the lesser petrosal nerve which synapses in the otic ganglion before joining the auriculotemporal nerve
What is the chorda tympani?
Branch of facial nerve (CN VII) that conveys taste sensation from the anterior 2/3rds of the tongue and carries secreto-motor (parasympathetic) innervation to the submandibular and sublingual glands
Describe the nerve supply to the submandibular gland and sublingual gland
Chorda tympani (branch of facial nerve, CN VII) carries secreto-motor (parasympathetic) fibres to the gland; joins the lingual nerve for a distance and then separates to go to the submandibular ganglion and then post-synaptic fibres from this ganglion innervate these two glands
Describe the body of the tongue
Anterior 2/3rds form the body of the tongue, and this is covered by mucosa that is derived from the ectoderm
Describe the root of the tongue
Posterior 1/3 forms the root of the tongue and is covered by mucosa derived from the endoderm
What is the sulcus terminalis of the tongue?
Forms the boundary between the anterior and posterior of the tongue (root and body) and it is V-shaped
What is the foramen cecum of the tongue?
The most posterior point of the sulcus terminalis (boundary between the body and root of the tongue)
Name the intrinsic muscles of the tongue
Superior longitudinal, inferior longitudinal, vertical and transverse
What is the function of the intrinsic muscles of the tongue?
Help in changing the shape of the tongue and moving the tip in different directions
What is the function of the extrinsic muscles of the tongue?
Attach the tongue to the bony structures around it and move the tongue during swallowing or sticking out
Name the extrinsic muscles of the tongue
Styloglossus - muscle to the styloid process
Genioglossus - muscle to the mandible (genu=chin)
Hyoglossus - muscle to hyoid bone
Palatoglossus - muscle to palate (move tongue during swallowing or sticking out)
What is the function of the palatoglossus?
Move the tongue during swallowing or sticking out
What is the nerve supply to the intrinsic and extrinsic muscles of the tongue?
Hypoglossal nerve (CN XII) which is a purely motor nerve EXCEPT for nerve supply to palatoglossus which is innervated by vagus nerve (CN X)
Where does the hypoglossal nerve travel?
Beneath the tongue
Describe the superior constrictor muscle of the pharynx
Originates from the medial pterygoid plate and the pterygomandibular raphe
Describe the middle constrictor muscle of the pharynx
Arises from the angle between the lesser and greater horns of the hyoid bone
Describe the inferior constrictor muscle of the pharynx
Arises from the oblique line on the lateral surface of the thyroid cartilage and the fascia covering the cricothyroid muscle
What is the midline pharyngeal raphe?
Formed by the 3 constrictor muscles of the pharynx
What is the nasopharynx?
From the base of the skull to the level of the soft palate
What is the oropharynx?
From the soft palate to the base of the tongue
What is the laryngopharynx (hypopharynx)?
Space above and behind the laryngeal opening
What are the four muscles of mastication?
Temporalis, masseter, medial pterygoid and lateral pterygoid
Which muscles of mastication act to close the mouth?
Temporalis, masseter and medial pterygoid
Which muscle of mastication acts to open the mouth?
Lateral pterygoid
What is the nerve supply to the muscles of mastication?
V3 (mandibular branch of trigeminal nerve)
What is the bony attachment of the inferior part of the tongue?
Hyoid bone
Name the suprahyoid muscles
Stylohyoid, digastric, geniohyoid and mylohyoid
Name the infrahyoid muscles
Sternohyoid, sternothyroid, thyrohyoid and omohyoid
Describe the role of the hyoid muscles in the early phases of swallowing
Contraction of mylohyoid and digrastic muscles (suprahyoids) –> raises hyoid bone and tongue –> pushes food against palate –> contraction of geniohyoid (suprahyoid) increases oropharynx lumen to receive food –> contraction of stylohyoid (suprahyoid) pulls hyoid bone and tongue further up and back to squeeze bolus down the laryngopharynx
Describe the composition of smooth muscle in the oesophagus
Has an inner circular layer of muscle and an outer longitudinal one. Upper third of oesophagus has striated skeletal muscle and the lower two thirds are made of smooth muscle
Where is the upper oesophageal sphincter and what is its function?
Found between the oesophagus and pharynx and it allows the passage of contents (intermittently opens and closes)
Where is the lower oesophageal sphincter and what is its function?
Found at the lowest end of the oesophagus where it meets the stomach and prevents the stomach contents from travelling back up the oesophagus
How is reflux prevented anatomically?
LOS is contracted permanently between meals, and the abdominal part of the oesophagus has a collapsed lumen all of the time under the effect of the intra-abdominal pressure
Where does the oesophagus lie in relation to the trachea?
Posterior to the trachea
Where does the oesophagus lie in relation to the vertebral column and the heart?
Oesophagus is anterior (in front of) the vertebral column but posterior to the heart
What is the transpyloric plane and where is it found?
The superior imaginary horizontal line of the 9 abdominal regions and it is located at the level of L1
What is the transtubercular plane and where is it found?
The inferior imaginary horizontal line of the 9 abdominal regions and it is located at the level of L5
Name the 9 regions of the abdomen
Right hypochondrium, epigastric, left hypochondrium
Right lumbar, umbilical, left lumbar
Right iliac, hypogastric/suprapubic, left iliac
Name the three anterolateral muscles of the abdomen from superficial to deep
External oblique, internal oblique, transverse abdominis
What is the anterior vertical muscle of the abdomen?
Rectus abdominis
What is the rectus sheath?
Aponeurosis (tendinous sheet) that encloses the rectus abdominis muscle and is formed by the external oblique, internal oblique and transverse abdominis muscles
What are the tendinous intersections in the abdomen?
Bands of tendons that divide the rectus abdominis muscle into the typical six pack
What is the linea alba?
Vertical midline tendinous intersection in the rectus abdominis muscle
How can you distinguish between the internal and external oblique muscles of the abdomen?
Internal oblique is directed towards the pack pockets and the external oblique is directed towards the front pockets
What is the action of the rectus abdominis muscle?
Flexion of the spine (bending forwards)
What is the action of the internal and external oblique muscles of the abdomen?
Sideways leaning
What are the three layers of muscle in the stomach, from superficial to deep?
Longitudinal muscle, circular muscle, oblique muscle layer
What are rugae?
A series of ridges produced by folding of the stomach wall
What ligament represents the obliterated umbilical vein?
Ligamentum teres hepatis
What are intraperitoneal organs?
Organs which are completely surrounded by the visceral peritoneal layer
What are retroperitoneal organs?
Organs that sit on the posterior abdominal wall and are NOT completely surrounded by peritoneum
Name the intraperitoneal structures of the GI tract
Stomach, jejunum, ileum, transverse and sigmoid colon
Name the retroperitoneal structures of the GI tract
Duodenum, ascending and descending colon
What are the divisions of the peritoneal cavity?
Lesser sac (omental bursa) is a small region that lies posterior to the stomach and the greater sac comprises the rest of the cavity
What is mesentery?
A double layer of peritoneum that attaches an organ to the posterior abdominal wall and allows passage of neurovascular supply to and from the organ
What is the mesentery of the colon called?
Mesocolon
What are omentum?
Peritoneum that passes from the stomach to an adjacent organ
Describe the lesser omentum
Connects the lesser curve of the stomach to the liver above and is two layers thick
Describe the greater omentum
Connects the greater curve of the stomach to the transverse colon below and is two layers of peritoneum (therefore 4 layers in total)
At what spinal level is the coeliac trunk found?
T12
What does the coeliac trunk supply?
Foregut structures, including liver and gall bladder, the stomach and lower oesophagus the spleen and part of the duodenum and pancreas.
What does the superior mesenteric artery supply?
Midgut structures: the intestine from the lower part of the duodenum to the left colic flexure and the pancreas
What does the inferior mesenteric artery supply?
Hindgut structures: large intestine from the left colic (or splenic) flexure to the upper part of the rectum, which includes the descending colon, the sigmoid colon, and part of the rectum
At what spinal level is the superior mesenteric artery found?
L1
At what spinal level is the inferior mesenteric artery found?
L3
What are the three branches of the coeliac trunk
Splenic artery, left gastric artery and the common hepatic artery
What are the four branches of the superior mesenteric artery?
Jejunal arteries, ileocolic artery, right colic artery and middle colic artery
What are the three branches of the inferior mesenteric artery?
Left colic artery, sigmoidal arteries and superior rectal artery
Which arteries supply the lesser curvature of the stomach?
Left and right gastric arteries
Which arteries supply the greater curvature of the stomach?
Left and right gastroepiploic arteries
What are short gastric arteries?
Branches of the splenic artery and supply the fundus region of the stomach
Describe the blood supply to the small intestines
SMA gives 15-18 branches to supply the small bowel. These branches unite to form loops or arches = arterial arcades within the small bowel mesentery. The arcades give rise to straight arteries = vasa recta
What differences are there between the arcades and the vasa recta of the jejunum and of the ileum?
The ileum has far more layers of arterial arcades before vasa recta are given off
How is the hepatic portal vein formed?
Inputs from the splenic vein (and inferior mesenteric vein branching from splenic) and the superior mesenteric vein
What is the function of the splenic vein?
Drains foregut
What is the function of the inferior mesenteric vein?
Drains midgut
What is the function of superior mesenteric vein?
Drains hindgut
What happens to the hepatic portal vein as it enters the liver?
Splits into left and right
Name the four parts of the duodenum
Superior, descending, horizontal and ascending
Describe the major duodenal papilla
Where the pancreatic duct and common bile ducts insert into the duodenum
Describe the minor duodenal papilla
Where the accessory pancreatic duct opens into the duodenum (superior to the major duodenal papilla)
Describe the common hepatic duct
Formed from the left and right hepatic ducts
Describe the cystic duct
The duct that stems from the gallbladder and joins to the common hepatic duct to form the common bile duct
Describe the common bile duct
Formed from the merging of the cystic duct and common hepatic duct
Describe the hepatopancreatic ampulla
Where the bile duct units with the pancreatic duct –> this opens into the major duodenal papilla
How are secretions into the duodenum controlled?
By the sphincter of Oddi
