Anatomy π« Flashcards
What is the digestive system divided into anatomically and functionally?
- a tubular gastrointestinal tract (GI tract), or digestive tract
- accessory digestive glands.
What is the extension of the gastrointestinal tract and what is its length?
The gastrointestinal tract extends from the mouth to the anus, is a continuous tube approximately 9 m long. It traverses the thoracic cavity and enters the abdominal cavity at the level of the diaphragm.
What are the organs and accessory digestive glands of the GIT?
- The organs of the GI tract include the oral cavity, pharynx, esophagus, stomach, small intestine, and large intestine.
- The accessory digestive glands include the salivary glands, liver, and pancreas.
What are the boundaries of the mouth cavity?
Superiorly: hard palate β soft palate.
Inferiorly: floor of the mouth formed by mylohyoid muscle β anterior 2/3 of the tongue.
Anteriorly and sides: lips β cheeks.
Posteriorly: oropharygeal isthmus separating it from the oropharynx
What are the divisions of the mouth cavity?
1- The vestibule
2- The mouth cavity proper
What is the vestibule of the mouth?
It is the cavity between the lips and the cheeks (externally) and the teeth and the gums (internally).
What is the mouth cavity proper?
It is the cavity enclosed by the teeth and the gums.
Attachment of The mucous membrane of the mouth cavity
It is firmly attached to the underlying bones (hard palate β alveolar process) and to the tongue. It is loosely attached to the floor and the cheeks and the lips.
What are the features of The mucous membrane of the mouth cavity?
β’ Frenulum of the tongue.
β’ Sublingual papilla
β’ Sublingual fold
What is the Frenulum of the tongue?
It is a median fold of the mucous membrane, connects the under surface of the tongue to the floor of the mouth.
What is the Sublingual papilla?
It is a small rounded elevation on the floor of the mouth, on each side of the frenulum, it receives the opening of the submandibular duct.
What is the Sublingual fold?
It is an elevation on the floor of the mouth extends posterolaterally, on both sides of the frenulum. It is produced by the sublingual salivary glands and shows the openings of their ducts.
What is the arterial supply of the mouth cavity?
by branches of external carotid artery
1- Facial artery: It gives superior labial and inferior labial branches to the upper and lower lips.
2- Lingual artery: It gives dorsal lingual and sublingual branches to the tongue and the floor of the mouth.
3- Maxillary artery: It gives alveolar and palatine branches to the teeth and the palate.
What is the nerve supply of the mouth cavity?
1- Roof: Greater palatine - lesser palatine - nasopalatine nerves (from sphenopalatine ganglion) Superior alveolar branches (from the maxillary nerve).
2- Floor: Lingual nerve (from the mandibular nerve).
3- Cheek: Buccal nerve (from the mandibular nerve).
What is the lymphatic drainage of the mouth cavity?
The lymphatic from the oral mucous membrane drains into: Submental, Submandibular and Upper deep cervical L.N.
What are the parts of the tongue?
1- Tip
2- Root
3- Surfaces
4- Sides
What is the tip of the tongue?
It is the tapering anterior free end.
What is the importance of the root of the tongue?
Transmits the vessels and nerve supply the tongue.
What are the surfaces of the tongue?
- Dorsal Surfaces
- Inferior Surfaces
Dorsal surfaces of the tongue
It is divided by V-shaped sulcus terminalis into:
A- anterior 2/3 (oral part): has lingual papillae of different shapes
B- posterior 1/3 (pharyngeal part): has elevations formed by lymphoid tissue nodules (lingual tonsil)
- There is a pit at the apex of the sulcus terminalis called foramen caecum.
Inferior surfaces of the tongue
- Directed downwards towards the floor of the mouth, Connected to the floor of the mouth by frenulum of the tongue.
- On each side of the frenulum, the lingual vessels and nerve run.
Sides of the tongue
Shows 5 vertical folds of mucous membrane called folia linguae.
What does (tongue-tied) mean? And how is it treated?
- When a short lingual frenulum restricts tongue movements, the person is said to be (tongue-tied)
- If this developmental problem is severe, the infant may have difficulty suckling. These functional problems can be easily corrected through surgery.
What are the muscles of the tongue?
The tongue has 2 groups of muscles intrinsic and extrinsic muscle.
A) Intrinsic muscle:
- Superior longitudinal muscle
- Inferior longitudinal muscle
- Vertical muscle
- Transverse muscle
B) Extrinsic muscles:
- Genioglossus.
- Hyoglossus.
- Styloglossus.
- Palatoglossus.
What are the functions of the intrinsic muscles of the tongue?
- Superior longitudinal muscle: It curls the tip upwards and rolls it posteriorly.
- Inferior longitudinal muscle: It curls the tip of the tongue downwards.
- Vertical muscle: It roll up the margins of the tongue and increase its transverse diameter.
- Transverse muscle: It narrows the tongue and increases its vertical diameter.
what is the definition of extrinsic muscles of the tongue?
These are muscles which arise from structures outside the tongue and inserted into the substance of the tongue.
Paralysis of the Genioglossus
The tongue has a tendency to fall posteriorly, obstructing the airway and presenting the risk of suffocation. Total relaxation of the genioglossus muscles occurs during general anesthesia; therefore, an airway is inserted in an anesthetized person to prevent the tongue from relapsing.
What happens when there is a lesion in the hypoglossal nerve (genioglossus paralysis)?
the tongue is deviated to the side of lesion on protrusion
What is the action of Genioglossus muscle?
Both sides: protrude the tongue.
One side: protrude the tongue and push it to the opposite side.
What is the motor nerve supply of the tongue?
All the intrinsic and the extrinsic muscles of the tongue are supplied by the hypoglossal nerve. except the palatoglossus muscle supplied by the pharyngeal plexus (vago-accessory complex).
What is the sensory nerve supply of the tongue?
β’ Anterior 2/3
- General sensations: lingual nerve.
- Taste sensation: chorda tympani.
β’ Posterior 1/3
- General and taste sensations: glossopharyngeal nerve.
β’ The most posterior part of the tongue General and taste sensations: vagus nerve
What is the origin of the lingual nerve?
posterior division of mandibular nerve (one of the trigeminal nerve divisions)
What is the course of the lingual nerve?
enters the oral cavity by passing on the medial surface of the mandible adjacent to the last molar tooth and deep to the gingiva (dangerous position). It loops under the submandibular duct, and ascends to enters the tongue.
What is the lymphatic drainage of the tongue?
- Tip of the tongue: drain into submental L.N then to lower deep cervical LN.
- Anterior 2/3: drain into submandibular L.N. then to lower deep cervical LN.
- Posterior 1/3:- drain into upper deep cervical L.N.
What is the distribution of the lingual nerve?
The lingual nerve carries general sensation from the mucosa on the floor of the oral cavity, and anterior two thirds of the tongue.
What is the arterial supply of the tongue?
Lingual artery
β’ Origin: from the external carotid artery.
Venous drainage of the tongue
β’ Lingual vein: Drain in the internal jugular vein.
What is the location of parotid gland?
Anterior and inferior to auricle; over masseter muscle
What is the duct of the parotid gland and where does it open?
Parotid (Stensenβs) duct opens into vestibule of the mouth opposite the upper second molar tooth
What is the parasympathetic Secretomotor nerve supply of the parotid gland?
glossopharyngeal nerve
What is the location of submandibular gland?
below the body of the mandible
What is the duct of the submandibular gland and where does it open?
Submandibular (Whartonβs) duct opens in sublingual papilla
What is the parasympathetic Secretomotor nerve supply of the submandibular gland?
facial nerve
What is the location of sublingual gland?
Under the mucous membrane of the floor of the mouth forms the sublingual fold
What is the duct of the sublingual gland and where does it open?
Several ducts open in the sublingual fold
What is the parasympathetic Secretomotor nerve supply of the sublingual gland?
facial nerve
What is the palate divided into?
Hard palate and soft palate
What does the hard palate form and what is it covered with?
- It forms the roof of the mouth (separates oral cavity from the nasal cavity).
- is covered with a mucous membrane.
What characterizes the surface of hard palate?
It has palatal rugae serve as friction ridges against which the tongue is placed during swallowing.
What is the hard palate formed of?
It if formed of
β’ Palatine process of the maxilla (anteriorly)
β’ Horizontal plate of the palatine bone (posteriorly)
What is the site of the soft palate?
β’ It is suspended from the posterior border of the hard palate, movable soft part separate oropharynx & nasopharynx.
Structures related to the soft palate
- Suspended from the middle lower border of the soft palate is a cone-shaped projection called the palatine uvula.
- Two muscular folds extend downward from both sides of the base of the palatine uvula.
- The anterior fold is called the palatoglossal arch, and the posterior fold is the palatopharyngeal arch.
- Between these two arches is the palatine tonsil.
What are the muscles of the palate?
Tensor palati
Levator palati
Palatoglossus
Palatopharyngeus
Musculus uvulae
What is the motor nerve supply of the palate?
All muscles of the palate are supplied by the pharyngeal plexus (vagoaccessory complex), except tensor palate supplied by the mandibular nerve.
- Lesion: Regurgitation of the food from the nose and the deviation of the uvula to the healthy side.
What is the sensory nerve supply to the palate?
β’ Nasopalatine
From the pterygopalatine ganglion, supplies the anterior part of the hard palate.
β’ Greater palatine nerve.
From the pterygopalatine ganglion, supplies the hard palate.
β’ Lesser palatine nerve
From the pterygopalatine ganglion, supplies the soft palate.
What is the autonomic nervous supply to the palate?
Parasympathetic: to the minor salivary gland of the palate from the facial nerve.
What is the arterial supply of the palate?
Palatine branches of maxillary artery
What is the site of the palatine tonsils?
- It lies in the tonsillar fossa one on each side of the lateral wall of the oropharynx.
- The tonsillar fossa in a triangular recess bounded by palatoglossal fold anteriorly and palatopharyngeal fold posteriorly. Its floor is formed by superior constrictor muscle of the pharynx
What is the nerve supply of the palatine tonsil?
Lesser palatine nerve, Glossopharyngeal nerve.
What is the arterial supply of the palatine tonsil?
The chief artery of the tonsil is tonsillar artery (from facial artery) It pierces the superior constrictor to enter the tonsil.
What is the Venous drainage of the palatine tonsil?
The veins from the tonsil pierce the superior constrictor to drain in to the pharyngeal venous plexus.
What is the lymphatic drainage of the palatine tonsil?
Drain in to the upper deep cervical lymph nodes.
What is tonsillectomy and where does bleeding usually occur?
Tonsillectomy (removal of the tonsils): Because of the rich blood supply of the tonsil, bleeding commonly arises from the large external palatine vein or, less commonly, from the tonsillar artery or other arterial twigs.
Development of the anterior 2/3 of the tongue
arises from three lingual buds from the first pharyngeal arch
- Tuberculum impar: a small median triangular elevation.
- Lateral lingual swellings: oval elevations on each side of the tuberculum impar.
Development: The lateral lingual swellings rapidly increase in size, fuse with each other, and overgrow the tuberculum impar.
Development of the posterior 1/3 of the tongue
arises from two elevations:
- The copula: From the second pharyngeal arches.
- The hypobranchial eminence: develops caudal to the copula from the 3rd and 4th pharyngeal arches.
Development:
- The copula is gradually overgrown by the hypobranchial eminence and disappears.
- The anterior two-thirds fuses with the posterior one-third. The line of fusion is indicated by a V-shaped groove the sulcus terminalis.
What is the state of the tongue at early stages?
At early stages, the tongue is adherent to the floor of the mouth. Later on, its anterior part becomes separated from the floor of the mouth by groove called alveolo-lingual groove.
What are the muscles of the tongue derived from?
occipital myotomes
What are the types of teeth and when do they appear?
- Deciduous (milk) teeth 20 : Begin to appear at 6th mouth, Completed by 2nd year
- Permanent teeth 32 : Begin to appear at 6th year
- Last molar (wisdom tooth) : appear 17-25 y
What is the arterial supply of teeth?
All teeth are supplied by branches of maxillary artery
Innervation of teeth
All nerves that innervate the teeth and gingivae are branches of the trigeminal nerve.
- Lower teeth: are supplied by the mandibular nerve [branch of trigeminal nerve].
- Upper teeth: are supplied by the maxillary nerve [branch of trigeminal nerve].
Introduction to the development of the digestive system
What are the structures that develop from the foregut?
1- Esophegus
2- Stomach
3- Duodenum
4- Liver & Biliary apparatus
Process of development of the esophagus
- Partitioning of cranial part of foregut caudal to primitive pharynx by tracheoesophageal septum into laryngotracheal tube (anteriorly) & esophagus (posteriorly).
- Initially, esophagus is short, but it elongates rapidly due to growth & descent of heart & lungs.
- Epithelium proliferates to increase the diameter of oesophagus & obliterates its lumen.
- Recanalization of esophagus occurs.
βthe respiratory system arises from the upper part of the digesive systemβ
What are the anomalies of the esophagus?
1- esophageal atresia
2- esophageal stenosis
3- tracheo-oesophageal fistula
4- short esophagus
5- Mega esophagus
What is the cause of esophageal atresia?
Failure of re-canalization of esophagus
What is the cause of esophageal stenosis?
Incomplete re-canalization of esophagus.
What is the cause of tracheo-oesophageal fistula?
incomplete separation of oesophagus from laryngeo-tracheal tube
What are the features of tracheo-oesophageal fistula?
it is associated with oesophageal atresia (so mother may present with polyhydramnios and preterm birth)
βdue to non swallowing of amniotic fluidβ
What are the features of short esophagus?
stomach may be displaced superiorly through esophageal hiatus (hiatus hernia)
What is the cause of mega-esophagus?
failure of neural crest cells to migrate to lower esophageal segment β-> so this segment becomes aganglionic (=has no ganglia). Absence of ganglia in this segment makes it constricted so the segment above becomes dilated (mega).
What is the feature of mega-esophagus?
Esophageal dilatation above the constricted (aganglionic) segment.
process of development of the stomach
1) Dilation in stomach Occurs & it becomes fusiform in shape.
2) Dorsal border of primitive stomach Grows faster than its ventral border.
This results in:
a. Ventral border becomes lesser curvature
b. Dorsal border becomes greater curvature.
3) Rotation of stomach: (due to growth of liver)
- Degree of rotation: 90 degrees in a clockwise direction (right)
- Axes of rotation: longitudinal & anteroposterior axes
What are the results of rotation of the stomach?
What are the anomalies of the stomach?
- Reversed rotation of stomach
- Congenital infantile hypertrophic pyloric stenosis
- Hour glass stomach
- Thoracic stomach (hiatus hernia)
What is the cause of reversed rotation of the stomach?
Rotation of stomach 90 degree in an anti-clockwise direction (to left).
What are the features of reversed rotation of the stomach?
Feature: (May present as a part of situs inversus and dextrocardia)
- lesser curvature moves to left & greater curvature moves to right
- left vagus supplies posterior wall of stomach & right vagus nerve innervates it anterior wall.
what is the feature of Congenital infantile hypertrophic pyloric stenosis?
- There is a marked hypertrophy & thickening of muscles of pylorus.
- Present with vomiting and low body weight
cough with suckling β-> problem in esophagus
vomitus with suckling β-> problem in pylorus
What causes hiatus hernia?
due to short esophagus
What is the time of development of the deudenum?
4th week
Process of development of duodenum
- Duodenum develops from endoderm of distal part of foregut & proximal part of midgut.
- Developing duodenum grows rapidly, forming a C- shaped loop that projects ventrally.
- As stomach rotates, Duodenal loop rotates to right, convex to right
- Lumen of duodenum becomes obliterated because of proliferation of its epithelium.
- Then duodenum becomes re-canalized due to apoptosis of the lining epithelium.
What is the blood supply of the duodenum?
By branches from celiac & superior mesenteric arteries Because of its development from foregut & midgut
What are the anomalies of the duodenum?
1) Duodenal stenosis: Incomplete re-canalization of duodenum.
2) Duodenal atresia: Failure of re-canalization
What is the time of development of the liver and biliary apparatus?
4th week
What are the sources of the liver?
arises from 3 sources:
- Hepatic diverticulum
- Mesoderm of septum transversum & its ventral mesentery
- Vitelline & umbilical veins
From where does the hepatic diverticulum develop?
Develops from endoderm of ventral aspect of caudal part of foregut.
What are the parts of the hepatic diverticulum?
- Pars Cystica
- Pars Hepatica (primordium of liver)
What is Pars cystica? And what does it give?
- A Small caudal part of hepatic diverticulum
- It gives gall bladder & its stalk forms cystic duct.
What is Pars Hepatica? And what does it give?
- larger cranial part of hepatic diverticulum.
- It gives the hepatocytes & biliary apparatus.
When does bile formation start in the embryo?
during 12th week.
Mesoderm of septum transversum & its ventral mesentery
within which, the hepatic diverticulum develops.
It gives
A- Kupffer cells & hematopoietic tissue
B- Capsule & stroma of liver
C- Peritoneal covering & ligaments of liver:
- Part [ ] liver & anterior abdominal wall becomes falciform ligament.
- Part [ ] liver & foregut (stomach & duodenum) will form lesser omentum.
what do vitelline & umbilical veins form?
While passing in septum transversum, they break to form Hepatic sinusoids
Development of extrahepatic biliary ducts
A. Right & left branches of pars hepatica form right & left hepatic ducts
B. Stem of pars hepatica forms common hepatic duct.
C. Stem of pars cystica will form cystic duct.
D. Stem of hepatic bud elongates to form common bile duct
What are the anomalies of gall bladder & extrahepatic biliary passages?
A. Anomalies of gall bladder:
- Absence
- Duplication
- Left βreversedβ
- Embedded
B. Anomalies of extra-hepatic biliary system:
- Extrahepatic biliary atresia.
- Dilatation of common bile duct.
- Duplication of common hepatic or common bile ducts.
Development of the mid gut
A. The midgut elongate to form a U shaped loop
B. Cecal swelling
C. Midgut loop has two limbs
D. Herniation (physiological hernia)
E. Reduction of hernia occur at 10th-12th week
F. Rotation of midgut loop
Rotation of midgut loop
What are the features of non-rotation of Midgut loop?
large intestine lies in left side & small intestine to right side of abdomen
What are the features of reversed rotation of the midgut?
- Duodenum lies anterior to superior mesenteric artery & transverse colon
- Small intestine lies on left side of abdomen & large intestine on right side with caecum in center.
What is the cloaca closed by and what is it formed from?
It is closed below by cloacal membrane (formed of endoderm and ectoderm with no mesoderm in between)
development of anal canal
what is the main arterial supply of the foregut?
celiac trunck (stomach, liver, spleen & upper part of duodenum)
what is the origin of the celiac trunk?
From front of abdominal aorta at level of upper border of L1 vertebra, just below aortic opening of diaphragm.
what is the termination of celiac trunk?
Ends by dividing into 3 terminal branches:
1. Left gastric
2. Hepatic
3. Splenic
branches of Gastro duodenal artery
branches of Proper hepatic artery
what is the arterial supply of the stomach?
what is the arterial supply of the duodenum?
arterial supply of the pancreas
course and relations of superior mesentric artery
- It descends downwards & to right with slight curve to left to end at right iliac fossa.
- It crosses 3rd part of duodenum.
- It descends in root of mesentery, superior mesenteric vein lies to its right side.
what are the branches of superior mesentric artery?
- Inferior pancreatico-duodenal artery
- Middle colic artery
- Right colic artery
- Ileocolic artery
- Jejunal & ileal branches
course of Inferior pancreatico-duodenal artery
Runs to right & upwards in groove between duodenum & head of pancreas.
course of Middle colic artery
enters between 2 layers of transverse mesocolon.
branches of Middle colic artery
(Divides into right & left branches close to transverse colon)
Right branch: anastomoses with ascending branch of right colic artery.
Left branch: anastomoses with ascending branch of superior left colic artery.
course & branches of Right colic artery
Close to ascending colon, it divides into ascending & descending branches:
- The ascending branch: anastomoses with middle colic artery.
- The descending branch: anastomoses with ileocolic artery.
course of Ileocolic artery
Runs downwards & to right towards right iliac fossa.
what are the branches of Ileocolic artery?
superior & inferior branches
from where do Jejunal & ileal branches arise? and what are their number?
- From convex side of the artery & enter between the 2 layers of mesentery of small intestine.
- 12-15 in number
what is the origin of inferior mesentric artery?
From front of abdominal aorta at L3.
what are the branches of the Upper left colic artery of inferior mesentric artery?
course and relations of Lower left colic (sigmoid) arteries
- Pass downward & to left
- They enter pelvic mesocolon.
what do Lower left colic (sigmoid) arteries anastomose with?
Anastomoses above with descending branch of upper left colic artery & below with superior rectal artery.
Arterial supply of the colon
sympathetic nerve supply to GIT
parasympathetic nerve supply to GIT
sensory nerve supply to GIT
what is the sensory nerve supply of the anterior abdominal wall?
Cutaneous: skin of anterior abdominal wall as
- Above umbilicus: supplied by T7, T8 & T9
- At level of umbilicus: supplied by T10
- Below umbilicus: supplied by T11 &T 12
what is the motor nerve supply to the anterior abdominal wall?
Motor: to muscles of abdominal wall
- Lower 5 intercostal Ns: oblique muscles, transversus abdominis & rectus abdominis
- Subcostal N: oblique muscles, transversus abdominis, rectus abdominis & pyrimidalis
what is the blood supply to the anterior abdominal wall?
- Lower 2 posterior intercostal and subcostal arteries
- epigastric arteries (superior and inferior)
- deep circumflex iliac artery
what is the origin of the external oblique muscle?
From the outer surface and lower border of the lower 8 ribs
what is the insertion of the external oblique muscle?
Posterior fleshy fibers:
- anterior 1/2 of the outer lip of iliac crest
Rest of the muscle: by an aponeurosis into:
- Xiphoid process & Linea alba
- Pubic crest & Pubic tubercle
- Anterior superior iliac spine
what is the definition of the inguinal ligament? (POUPARTβS LIGAMENT)
Thickened folded lower free border of external oblique aponeurosis
attachment of the inguinal ligament
Laterally:
- Anterior superior iliac spine (A.S.I.S.)
Medially:
- Pubic tubercle (mainly)
- linea alba (through reflected ligament)
- pectineal line (through lacunar ligament)
what is the origin of the Internal oblique muscle?
- Anterior fibers: Lateral 2/3 of the inguinal ligament (upper surface)
- Lateral fibers: Anterior 2/3 of iliac crest (intermediate area)
- Posterior fibers: lumbar fascia
what is the insertion of the Internal oblique muscle?
Posterior fibers: fleshy fibers into10th ,11th & 12th costal cartilages
Lateral fibers: Form broad aponeurosis which is attached to
- 7th,8th and 9th costal cartilages
- Upper part of linea alba
what is the origin of cremastric muscle & fascia?
Lower arching fibers of internal oblique
what is the insertion of cremastric muscle & fascia?
Pubic tubercle (form complete loop)
what is the origin of the transversus abdominis muscle?
- Lateral 1/3 of inguinal ligament (upper surface)
- Anterior 2/3 of iliac crest (inner lip)
- Lumber fascia
- Lower six ribs (inner surfaces)
what is the insertion of the transversus abdominis muscle?
Upper fibers: remain fleshy attached to xiphoid process
Middle fibers: end in aponeurosis attached to xiphoid process & linea alba
Lower fibers: Form an arch higher than that of internal oblique & end in aponeurosis
compare between the anterior wall and posterior wall of rectus sheath
what are the contents of the rectus sheath?
compare between superficial inguinal ring & deep inguinal ring
compare between inguinal triangle & lumbar triangle
compare between direct inguinal hernia & Indirect inguinal hernia
