Block 3 (Josie's Notes) Flashcards
Name the boundaries of the mouth?
- Roof - Hard (front) and soft (back) palate
- Floor - Mylohyoid muscle
- Lateral walls - Cheeks
- Anterior - Lips
- Posterior - Palatoglossal fold
What divides the mouth into two spaces?
- Teeth
What are the two areas of the mouth?
- Vestibule - Area between the teeth and lips
- Oral cavity proper - Area behind the teeth
What are the three glands?
- Parotid gland
- Submandibular gland
- Sublingual gland
Describe the parotid gland?
- Largest gland
- Lies outside the boundaries of the oral cavity
- Parotid duct passes across external Describe the submandibular gland surface of the masseter muscle then penetrates the buccinator muscle of the cheek and opens into the oral cavity
- Secretes serous, watery saliva
Describe the submandibular gland?
- Hooked shaped
- Inferior to the angle of the mandible
- Duct emerges to open on papillia beside the base of the frenulus of the tongue
Describe the sublingual gland?
- Smallest gland
- Immediately lateral to submandibular duct
- Superior margin raises an elongated fold (sublingual fold)
- Minor sublingual ducts open onto the crest of the sublingual fold
- Major sublingual duct occasionally drains anterior part of gland, opens with submandibular gland at sublingual caruncle
What are the three major external regions of a typical tooth?
- Crown - Visible portion above gums
- Root
- Neck - Constricted junction of the crown and root
What are the three types of teeth?
- Incisors - Cutting food
- Canines - Tearing food
- Molars - Crushing and grinding food
What are the two muscles of the tongue?
- Extrinsic tongue muscles - Move tongue side to side and in and out
- Intrinsic tongue muscles - Alter shape of tongue, involved in swallowing and speech
Describe the histology of the oral cavity?
- Thick stratified squamous epithelium supported by lamina propria
- In mobile areas (e.g. soft palate, underside of tongue, floor of mouth, cheeks, and lips) the epithelium is not keratinised
- In areas such as gums, hard palate, and most of the tongues upper surface, the epithelium is keratinised
What arteries supply the oral cavity?
- Branches of external carotid artery
- Lingual artery supplies the tongue
What veins drain the oral cavity?
- Veins of the palate drain into the pterygoid venous plexus
- Lingual veins drain into the internal jugular vein
Describe the lymphatic drainage of the oral cavity?
- Submandibular
- Submantal
- Deep cervical
Which nerves supply the oral cavity?
- Inferior alveolar nerve - Lower teeth
- Lingual nerve - Anterior two thirds to the tongue
- Glossopharyngeal nerve - Posterior third of the tongue
Name the four muscles of mastication?
- Masseter
- Temporalis
- Medial pterygoid
- Lateral pterygoid
What does the masseter muscle do?
- Elevates the mandible
What does the temporalis do?
- Elevation and retraction of the mandible
What does the medial pterygoid do?
- Elevation and side-to-side mandible movement
What does the lateral pterygoid do?
- Protrusion and side-to-side mandible movement
What is the buccinator?
- Accessory muscle of mastication
- Pulls back the angle of the mouth and flattens the cheek area
What nerve innervates the muscles of mastication?
- Mandibular nerve (branch of trigeminal)
What three areas is the pharynx divided into?
- Nasopharynx
- Oropharynx
- Larngopharynx
Where is the oropharynx?
- Posterior to the oral cavity
- Inferior to the soft palate
- Superior to the upper margin of the epiglottis
What structure marks the border between the mouth and the pharynx?
- The palatoglossal arch (formed by the glossopalatine muscle)
What is the palatopharyngeal arch?
- Larger than the palatoglossal arch
- Projects further towards the midline
What is the name of the depression between the palatoglossal and palatopharyngeal arches?
- Tonsillar fossa
What structure occupies the tonsillar fossa?
- Palatine tonsil
Where are the lingual tonsils?
- Mucosa covering the posterior third of the tongue
What is the oesophagus?
- Muscular tube passing between the pharynx and the stomach
Where does the oesophagus start and end? (2)
- Begins at cricoid cartilage C6
- Ends at the cardiac opening of the abdomen T10
Where is the upper oesophageal sphincter?
- Between the pharynx and oesophagus
- Relaxes during swallowing
Where is the lower oesophageal sphincter?
- Between the oesophagus and the stomach
- Reinforced by diaphragmatic crus - prevents gastro-oesophageal reflux
Name the four structures that the oesophagus can be compressed and narrowed?
- Pharyngo-oesophageal junction
- Arch of the aorta (superior mediastinum)
- Left main bronchus
- Gastro-oesophageal junction (oesophageal hiatus)
Describe the histology of the oesophagus?
- Non-keritanised stratified squamous epithelium
What arteries supply the oesophagus?
- thoracic aorta
- bronchial arteries
- ascending branches of the left gastric artery
What nerves supply the oesophagus?
- Vagus and sympathetic trunk
- Splanchnic nerves involved in detection of pain
Name the four areas of the stomach?
- Cardia - Surrounds the opening of the oesophagus
- Fundus - Area above the cardiac orifice
- Body - Largest region of the stomach
- Pylorus - Divided into the pyloric antrum and pyloric canal
What is the greater curvature?
- Point of attachment for gastrosplenic ligament and greater omentum
What is the lesser curvature?
- Point of attachment for the lesser omentum
What secreted gastric juice?
- Gastric mucosal glands
What does gastric juice contain? (5)
- HCl
- Mucus
- Pepsin
- Lipase
- Intrinsic factor
What are rugae?
- Folds in the stomach lining when the stomach is empty
- Folds flatten after eating when the stomach is distended
Describe the pylorus?
- Marked on the surface by the pyloric constrictor
- Contains a thickened ring of gastric circular muscle (pyloric sphincter)
- Pyloric sphincter surrounds the distal opening of the stomach (pyloric orifice)
Describe the histology of the stomach?
- Simple columnar
What are the three types of exocrine cells in the glands?
- Mucous neck cells - Secrete mucous
- Parietal cells - Produce intrinsic factor and HCl
- Chief cells - Secrete pepsinogen and gastric lipase
What are G cells?
- Secrete gastrin (stimulates gastric acid secretion)
- Found mainly in the pyloric antrum
What are the two sets of gastric lymph nodes?
- Superior gastric glands
- Inferior gastric glands
Describe the innervation of the stomach?
- Sympathetic - Splanchnic nerves and celiac ganglion
- Parasympathetic - Vagus
What are the three divisions of the small intestine?
- Duodenum
- Jejunum
- Ileum
What marks the beginning and the end of the small intestine?
- Beginning - Pyloric orifice
- End - Ileocecal fold
Where is the duodenum located?
- Next to the head of the pancreas
- Retroperitoneal (except at the beginning which is connected to the liver by the hepatoduodenal ligament)
What are the four parts of the duodenum?
- Superior part
- Descending part
- Inferior part
- Ascending part
Where is the major duodenal papilla located and what is it?
- Located in the descending part of the duodenum
- Entrance for bile and pancreatic ducts
What is the minor duodenal papilla?
- Entrance for accessory pancreatic duct
What is the suspensory muscle of the duodenum also known as?
- Ligament of Treitz
What does the ligament of Treitz do?
- Connecting the junction between the duodenum, jejunum, and duodenaljejunal flexure to connective tissue
Describe the distinguishing features of the jejunum?
- Proximal two-fifths of the small intestine
- Thicker wall
- Inner mucosal lining has numerous prominent folds that circle the lumen (plical circulares)
- Less prominent arterial arcades
- Longer vasa recta
- Supplied by jejunal arteries from the superior mesenteric artery
Describe the distinguishing features of the ileum?
- Distal three-fifths of the small intestine
- Thinner walls
- Fewer/less prominent plical circulares
- Shorter vasa recta
- More arterial arcades
- More mesenteric fat
- Supplied by ileal arteries from the superior mesenteric artery
What does MALT stand for?
- Mucosa-associated lymphoid tissue
What are Peyer’s patches?
- Aggregations of GALT (gut associated lymphoid tissue)
- Usually in the ileum
- Important for the immune surveillance of the intestinal lumen and in facilitating the generation of the immune response within the mucosa
What is the purpose of the ileocecal folds?
- Prevents reflux from the cecum to the ileum
- Regulates passage of contents from the ileum to the cecum
What marks the beginning and the end of the large intestine?
- Beginning - Distal end of ileum (Ileocecal folds)
- Ends - Anus
What does the large intestine do?
- Absorbs fluids and salts from the gut contents - forms faeces
What are the five structures of the large intestine?
- Cecum
- Appendix
- Colon
- Rectum
- Anal canal
What are the four divisions of the colon?
- Ascending colon
- Transverse colon
- Descending colon
- Sigmoid colon
What is the flexure between the ascending colon and transverse colon?
- Right colic flexure (hepatic flexure)
- Just below the liver
What is the flexure between the transverse colon and the descending colon?
- Left colic flexure (splenic flexure)
- Just below the spleen
What are omental appendices?
- Peritoneal covered accumulations of fat
What are teniae coli?
- Longitudinal muscle in the walls
- Three narrow bands
What are haustra?
- Bulges of the colon
What are plica semilunaris?
- Semilunar folds of mucosa separating the haustra coli
Describe the four layers of epithelium of the lower GI tract? (4)
- Mucosa - Columnar epithelia, including goblet cells
- Submucosa - Contains blood vessels and meissner’s nerve plexus
- Muscularis propria - Contain the inner circular, outer longitudinal muscles and myenteric (auerbach’s) nerve plexus
- Serosa - Visceral peritoneum
What is the arterial supply to the colon?
- Superior mesenteric artery - Ascending and part of the transverse colon
- Inferior mesenteric artery - Rest of the transverse, descending, and sigmoid colon
Describe the lymphatic drainage of the colon?
- Thoracic duct (empties into the left subclavian vein)
What is the enteric nervous system (ENS)?
- Mesh-like system of neurons that controls the function of the GI system
What are the two ganglia of the ENS?
- Myenteric (Auerbach’s) plexus
- Submucosal (Meissner’s) plexus
What is the myenteric plexus?
- Located in the muscularis propria
- Receives messages from vagus nerve
- Contracts muscle cells - peristaltic waves
What is the submucosal plexus?
- Located in the submucosa
- Function is not clearly defined
- May be partly inhibitory in the stomach
- In the intestines it is believed to work with the myentetic plexus in producing peristaltic waves and increasing digestive secretions
What is the start of the rectum called?
- Rectosigmoid junction
What are the rectal folds?
- Transverse folds that support the weight of faecal matter
Is the rectum covered by peritoneal?
- Upper third is covered by peritoneum
- The rest is retroperitoneal
What are anal columns?
- Vertical folds produced by an infolding of the mucous membrane and some of the muscular tissue
- Contain a network of arteries and veins
What is the opening of the anal canal called?
- The anus
What kind of muscle is the internal sphincter?
- Smooth muscle (involuntary)
What does the levator ani muscle do?
- Plays a vital role in supporting pelvic organs
- Prevents urinary incontinence
What kind of muscle is the external sphincter?
- Skeletal muscle (voluntary)
What is the arterial supply to the rectum and anal canal?
- Superior, middle, and inferior rectal arteries (from inferior mesenteric artery)
- Superior, middle, and inferior rectal arteries (from inferior mesenteric artery)
Describe the lymphatic drainage of the rectum and anal canal?
- Superficial inguinal lymph nodes (lower half)
- Internal iliac lymph nodes (upper half)
Which nerves innervate the rectum and anal canal?
- Inferior hypogastric nerve plexus (upper half)
- Somatic inferior rectal nerve (lower half)
What are the two layers of superficial fascia?
- Superficial fatty layer (camper’s)
- Deep membranous layer (scarpa’s)
What is camper’s fascia?
- Superficial fatty layer of superficial facia
- Contains fat, varies in thickness
- Continuous over inguinal ligament with superficial fascia of the thigh
What is scarpa’s fascia?
- Deep membranous layer of superficial fascia
- Thin and membranous, contains little or no fat
- Continues into thigh (fuses with deep fascia)
What are the five muscles in the anterolateral group of abdominal wall muscles?
- Three flat muscles - Pass anteriorly and are replaced by aponeurosis as they continue towards the midline
- External oblique
- Internal oblique
- Transverse abdominis
- Two vertical muscles - Near midline, enclosed within a tendinous sheath formed by aponeurosis of the flat muscles
- Rectus abdominis
- Pyramidalis (only in 10%)
What are the vertical muscles enclosed in?
- Rectus sheath - Layering of aponeurosis of external and internal oblique and transverse abdominis
- Encloses upper three-quarters of the rectus abdominis
What is the transversalis fascia?
- Thin aponeurotic membrane which lies between the inner surface of the transverse abdominis and the extraperitoneal fascia
What is extraperitoneal fascia?
- Connective tissue which separates the transversalis fascia from the parietal peritoneum
What is the peritoneum?
- Thin serous membrane
- Lines walls of abdominal cavity, at points reflects on to the viscera (organs of the abdominal cavity)
- Parietal peritoneum - Lining walls
- Visceral peritoneum - Lining viscera
What is the space between the peritoneum called?
- Peritoneal cavity
- Closed in men, semiclosed in women (uterine tubes)
- Potential space, contains thin film of fluid to act as a lubricant and fight infections
What are the two sacs of the peritoneal cavity?
- Greater sac - Most of the peritoneal cavity
- Lesser sac (omental bursa) - Smaller sac posterior to the liver and stomach, continuous with the greater sac through the omental foramen
What is the inguinal canal?
- Slit-like passage
- Begins at the deep inguinal ring
- Extends downwards and medial for about 4cm
- Ends at the superficial inguinal ring
Name the contents of the inguinal canal?
- Gential branch of genitofemoral nerve
- Ilioinguinal nerve
- Spermatic cord (men)
- Round ligaments of uterus (women)
Where is the deep inguinal ring located?
- Midpoint between anterior superior iliac spine and pubic symphysis
Where is the superficial inguinal ring located?
- Superior to the pubic tubercle, triangular opening in the aponeurosis of the external oblique
Name the boundaries of the inguinal canal?
- Anterior wall - Aponeurosis of external oblique
- Posterior wall - Transversalis fascia
- Roof - Arching fibres of transverse abdominus and internal oblique
- Floor - Inguinal ligament
What are the two surfaces of the liver?
- Diaphragmatic surface - Anterior, superior, and posterior
- Visceral surface - Inferior