Anatomy Flashcards
1
Q
What is the length of the pharynx? diameter?
A
12 cm in total; widest at the epipharynx and narrowest at the laryngopharynx
2
Q
Which part of the pharynx transmits both food and air?
A
Oropharynx/Mesopharynx
3
Q
Which parts of the pharynx transmits air only?
A
Nasopharynx and Laryngopharynx
4
Q
Location of the nasopharynx
A
found posterior to the nasal cavities
5
Q
Location of the oropharynx
A
found posterior to the oral cavity
6
Q
Location of the laryngopharynx
A
found posterior to the opening of the larynx and posterior surface of the larynx
7
Q
Which part of the pharynx is non-collapsible?
A
Nasopharynx / Epipharynx
8
Q
What are the boundaries of the pharynx?
A
Roof: Base of skull, Sphenoid and Occipital bone
Anterior: Continuous with nasal and oral cavities and pharynx
Base: Continuous with esophagus [lower border of C6] and lower border of cricoid cartilage
Posterior: Prevertebral layer of deep cervical fascia
9
Q
What structure separates the pharynx from the cervical fascia?
A
Prevertebral layer of deep cervical fascia
10
Q
What are the 8 attachments points of the pharyngeal wall?
A
Medial Pterygoid plate
Pterygoid hamulus
Pterygomandibular raphe
Mandible
Tongue
Hyoid Bone
Thyroid cartilage
Cricoid cartilage
11
Q
What structures form the roof of the nasopharynx?
A
Body of sphenoid bone
Basilar portion of occipital bone
12
Q
What structure is found at the posterior-superior portion of the Nasopharynx?
A
Pharyngeal tonsils/adenoids
13
Q
What structure forms the floor of the nasopharynx?
A
Soft Palate
14
Q
What passage forms the communication between the nasopharynx and oropharynx
A
Pharyngeal isthmus, which is found posterior to the soft palate
15
Q
What structure forms the anterior wall of the nasopharynx?
A
Choanae [post nasal aperture]
16
Q
What structure forms the posterior wall of the nasopharynx?
A
Superior pharyngeal constrictor [muscle]
17
Q
What structures are found on the posterior wall of the nasopharynx?
A
Nasopharyngeal tonsils/adenoid
Pharyngeal bursa
18
Q
Describe the histological changes seen in the gastroesophageal junction?
A
Abrupt epithelial transition from non-keratinized stratified squamous to simple columnar cells
Cardiac glands are present
19
Q
What are cardiac glands?
A
Mucous secreting glands found in the mucosa [specifically in the lamina propria]
20
Q
What type of epithelial cells line the esophagus?
A
Non-keratinized stratified squamous epithelium
21
Q
Describe the adventitia of the esophagus
A
Its CT merges with the CT of the surrounding structures, as it passes around them, giving it support and supplying it with BV
22
Q
Why is the esophagus lined superficially by adventitia not by serosa?
A
It is not covered by mesothelium [as it doesn’t push through a serous-lined cavity]
23
Q
What type of CT is found in the submucosa of the esophagus?
A
Areolar CT [+ elastic fibers that assist in closing the distended tube]
24
Q
What is found in the submucosa of the esophagus?
A
Areolar CT
BV
Mucous glands
25
Describe the changes seen in the Muscular Externa throughout the length of the esophagus?
Superior 1/3- Skeletal Muscle
Middle 1/3- Skeletal and Smooth muscle
Inferior 1/3- Smooth Muscle
26
Describe the structure of the Muscular externa?
Inner circular and outer longitudinal muscles
27
In order from deep to superficial, what are the layers that make up the esophagus [histology]?
Lumen of Esophagus
Mucosa
Muscularis mucosa [part of the mucosa]
Submucosa
Muscularis externa
Adventitia
28
What type of muscle is the muscularis mucosae?
Smooth muscle
29
Where are stem cells found in the esophagus?
In the stratum basale
30
What innervates the esophagus?
Esophageal nerve plexus
31
What nerves form the esophageal plexus?
Vagal trunks
Thoracic Sympathetic trunks
Periarterial plexuses
Middle Cervical ganglion
32
What is the parasympathetic supply to the esophagus?
Dorsal Vagal nuclei
Afferent fibers whose cell bodies are in the inferior ganglion of the vagi- for reflexes
33
What are the branches of the vagal trunks?
Anterior and Posterior gastric branches
34
How do the thoracic sympathetic trunks supply the esophagus?
Via Greater and Lesser abdominopelvic splanchnic nerves [T5-T12 spinal segments]
35
What structures are found around the periarterial plexus?
around the left gastric and inferior phrenic arteries
36
What part of the esophagus does middle cervical ganglion innervate?
The upper part
37
What innervates the lower part of the esophagus exclusively?
T1-T4 fibers
38
What innervates the striated muscles of the esophagus?
Vagus nerve [nucleus ambiguous]
39
What innervates the smooth muscles of the esophagus\?
Vagus nerve [dorsal vagal nucleus]
40
What nerve is responsible for the general sensation in the esophagus?
Vagus nerve
41
What are the two types of sympathetic fibers supplying the esophagus?
Postganglionic fibers [cell bodies in sympathetic ganglion]
Afferent fibers for pain [cell bodies in DRG]
42
What is responsible for pain signals and mechanosensory signaling?
Sympathetic nerves
Vagal Afferents
43
What is responsible for coordination distal esophagus peristalsis with relaxation of LES during swallowing?
It is mediated by intrinsic nitrergic inhibitory neurons under vagal control
44
What group of lymph nodes does lymph drain into in cases of cancer of the lower esophagus?
Mediastinal lymph nodes
45
Where does lymph from the cervical part of the esophagus drain into?
Lymph from cervical part → Inferior deep cervical lymph nodes
46
Where does lymph from the thoracic part of the esophagus drain into?
Lymph from thoracic part → posterior mediastinal lymph nodes
47
Where does lymph from the Lower 1/3 and Abdominal part of the esophagus drain into?
Lymph from Lower 1/3 + AbdominaL → Left gastric lymph nodes → efferent vessel of left gastric nodes → celiac lymph nodes
48
Where do veins from the thoracic part of the esophagus drain into?
Hemiazygous veins → Azygous vein
49
Where do veins from the cervical part of the esophagus drain into?
Inferior thyroid veins
50
Where do veins from the abdominal part of the esophagus drain into?
2 ways: Mucosal submucosal veins
→ left gastric veins → portal venous system
→ esophageal veins → hemi/azygous veins → systemic venous system
51
Where do we have porto-caval anastomosis in the esophagus?
Anastomosis between left gastric veins tributaries + azygous veins tributaries
Gastric veins = portal system
Azygous vein = systemic vein system
52
What is hiatus hernia?
Condition that involves expansion of the esophageal hiatus and herniation of the stomach through the diaphragm into mediastinum
Either asymptomatic or associated with GERD
53
What are the types of hiatus hernia?
Sliding type
Para-esophageal
Mixed type
54
What is a complication of Para-esophageal hernias?
Obstruction or necrosis of herniated stomach
55
What is the more common type of hiatus hernia?
Sliding [90%]
56
In what population is hiatus hernias more common?
Obese and elderly people
57
Define a physiological sphincter?
A tubular structure that functions as a sphincter even though it does not have sphincter muscles
58
What type of Sphincter is the gastroesophageal sphincter?
Physiological sphincter
59
What is another name for the gastroesophageal sphincter?
Cardiac Sphincter
60
What is a surgical marker for the gastroesophageal sphincter in adults?
A fat pad found over the anterior surface of the junction. it is visible beneath the peritoneum
61
Where is the gastroesophageal junction found?
left to the T11 vertebrae on horizontal plane that passes through the tip of the xiphoid process [left 7th intercostal cartilage]
62
Surgically, what designates the gastroesophageal junction?
A z-jagged line that demarcates the sudden epithelial changes
63
What type of muscle is the muscular wall of the abdominal esophagus?
Smooth muscles
64
What forms the lower esophageal sphincter?
Narrowing of the diaphragmatic musculature, forming esophagal hiatus
65
Describe the shape of the abdominal esophagus?
Trumpet shaped [1.25 cm], broader at the cardiac orifice as compared to the diaphragmatic aperture
66
Where is the abdominal esophagus found?
Left of midline behind 7th costal cartilage, enter the abdomen through esophageal hiatus at T10. Ends at gastroesophageal junction
67
Which structure is found anterior to the abdominal esophagus?
Left lobe of liver
68
Which structures are found posterior to the abdominal esophagus?
Left Crus
Left Inferior phrenic vessels
Left Greater and Lesser Splanchnic nerves
69
Describe the right border of the abdominal esophagus
Continuous with the lesser curvature of the stomach
70
What separates the abdominal esophagus from the stomach?
Cardiac notch separates the left border of the esophagus from the fundus of the stomach
71
What structures are found in the CT and visceral peritoneum that lines the surface of the Abdominal esophagus?
Anterior and Posterior Vagus nerves
Esophageal branches of the left gastric vessels
72
What is the gastroesophageal ligament?
Ligament that attaches the margins of the muscular esophageal hiatus to the diaphragm
73
What forms the gastroesophageal ligament?
Two circumferential layers of elastin-rich CT and smooth muscle fibers
74
Describe the inferior layer of the gastroesophageal ligament
Thin and loosely attached to the esophagus
Extension of sub peritoneal transversalis fascia below diaphragm
75
Describe the superior layer of the gastroesophageal ligament
Thicker [more elastin] and runs cranially and obliquely to fuse firmly with the wall of the esophagus
Continuous with sub pleural end-thoracic fascia above diaphragm
76
Function of Gastroesophageal ligament?
Anchors esophageal to crural muscle fibers of diaphragm
Limits upward and downward mobility of the esophagus within the hiatus
77
What forms the Gastrophrenic ligament?
Peritoneal reflection posterior to esophagus and continues directly onto posterior surface of fundus of stomach
78
What structures are found in the Gastrophrenic ligament?
Esophageal branches of Left Gastric vessels
Celiac branches of Posterior Vagus
79
Which ligament also forms a mesentery to the abdominal esophagus?
Gastrophrenic ligament
80
Which part of the esophagus is a common site of cancer
Natural constrictions [Cervical, Thoracic and Diaphragmatic constrictions]
81
What are the three natural constrictions in the esophagus?
Cervical constriction
Thoracic constriction
Diaphragmatic constriction
82
What forms the cervical constriction of the esophagus?
Cricopharyngeus muscle
83
What esophageal constriction is referred as the UES?
Cervical constriction of the esophagus
84
Where does the cervical constriction of the esophagus begin at?
Pharyngoesophageal junction, 15 cm away from incisors
85
What forms the thoracic constriction?
1- Arch of aorta [22.5 cm away from incisors, seen anteroposterior]
2- Left main bronchus [27.5 cm away from incisors, seen laterally]
86
What forms the diaphragmatic constriction of the esophagus?
As it passes through the esophagus hiatus of diaphragm [40 cm from incisor teeth]
87
Describe the two curvatures of the esophagus
1- Curves to the left at the thoracic [T1]
2- Curves to the left at T7
88
Describe the two curvatures of the esophagus
1- Curves to the left at the thoracic [T1]
2- Curves to the left at T7
89
What structures are found to the left of the esophagus?
Thoracic duct
90
What structures are found on each side of the esophagus?
Thyroid Lobes
91
What structures are found anterior to the esophagus?
Trachea
Thyroid
Recurrent Laryngeal nerve
92
What structures are found posterior to the esophagus?
Vertebral column
Prevertebral muscles
93
Boundaries of the esophagus
Extends from lower border of criocoid cartilage [C6] to gastroesophageal junction
94
What is the length of the esophagus? Diameter?
25 cm long, ~ 2cm diameter
95
What structures are found anterior to the thoracic esophagus?
Trachea
Right pulmonary artery
Pericardium
Left Atrium
Left Bronchus
96
What structures are found posterior to the thoracic esophagus?
Vertebral column
Thoracic duct
Azygous vein
Thoracic aorta
97
What is the phrenicoesophageal ligament?
an extension of the inferior diaphragmatic fascia
98
What is the function of the phrenicoesophageal ligament?
Connects esophagus flexibly to the diaphragm and permits independent movement of each structure during respiration and swallowing [+ limits upward movement of esophagus]
99
What type of cells line the epithelium of the pharynx?
Non-keratinized stratified squamous epithelium
100
What are the histological characteristic of the pharnyx
NKS-squamous epithelium
Prominent elastic fibers in LP
Striated muscles
No muscularis mucosa
No submucosa
101
Where do all arteries that supply the pharynx originate from?
External carotid artery
102
What vessels supply the pharynx?
Ascending Pharyngeal
Ascending Palatine artery
Tonsillar branch
Dorsal lingual
Greater Palatine
Pharyngeal
Pterygoid
103
Which artery that supplies the pharynx is a branch of the facial artery?
Ascending palatine
Tonsillar branch
104
Which artery that supplies the pharynx is a branch of the maxillary artery?
Greater palatine
Pharyngeal
Pterygoid artery
105
Which artery that supplied the pharynx is a direct branch of the External carotid artery?
Ascending pharyngeal artery
106
Which artery that supplies the pharynx is a branch of the lingual artery?
Dorsal lingual artery
107
Where does lymph collected from the pharynx drain into?
→ retropharyngeal and deep cervical lymph nodes
108
Where does the pharyngeal plexus drain into?
IJV and Facial veins
109
What are the three outer circular muscle layers of the pharynx?
Superior, Middle and Inferior Constrictor
110
What are the three longitudinal muscles of the pharynx?
Salpingopharyngeus
Palatopharyngeus
Stylopharyngeus
111
What forms the pharyngeal raphe?
when muscles of the pharynx course posterolaterally to the midline and meet forming this raphe
112
What are the two parts of the inferior constrictor?
Thyropharyngeus and Cricopharyngeus muscles
113
What lines the constrictor muscles internally?
Pharyngobasilar fascia
114
What lines the constrictor muscles externally?
Buccopharyngeal fascia
115
What is the action of the superior constrictor muscle
contributes to closing oropharyngeal isthmus and pushes bolus down
116
Describe the structure of the superior constrictor muscle
quadrilateral thin muscle, palest
117
What is the action of the middle constrictor muscle?
contributes to pushing food bolus down
118
Describe the structure of the middle constrictor muscle
Fan-shaped muscle
119
What is the significance of the middle constrictor muscle?
forms part of floor of carotid triangle of neck
120
What structures are found lateral to the origin of the middle constrictor muscle?
Hyoglossus muscle
Posterior belly of digastric muscle
Stylohoid muscle
121
Describe the structure of the inferior constrictor muscle
thickest of the constrictor muscles
122
What is the significance of the inferior constrictor muscle?
Form floor of carotid triangle [same as middle constrictor]
related to medial surface of lobe of thyroid gland
123
What is the action of the inferior constrictor muscle?
contributes to pushing the food bolus down
124
What is the significance of the two origins of the inferior constrictor muscle?
Thyropharyngeal part : propulsive in action
Cricopharyngeal part: acts as a sphincter of the lower pharynx
Thyropharyngeal contracts to push food down while cricopharyngeal relaxes to accept the food bolus into the esophagus
125
What nerve innervates the inferior constrictor muscle?
Thyropharyngeus portion: Pharyngeal plexus
Cricopharyngeal portion: recurrent laryngeal nerve
126
Which part of the inferior constrictor is considered weak? Why?
Lower part of thyropharngeal as its not covered by another constrictor muscle
127
What is the Killian's triangle?
triangular area in muscular wall of pharynx between the cricopharynxgeus and thyropharyngeus,
128
What is the anatomical abnormality causing Zenker's diverticulum?
When thyropharyngeal portion of the inferior constrictor contracts, the cricopharnygeus does not relax due to neuromuscular incoordination [each has separate innervation]
129
What is Killian's dihiscence?
location of minor resistance [lower part of thyropharyngeus]
130
What is trotter's triad?
conductive deafness
Ipsilateral paralysis of soft palate
Trigeminal neuralgia
131
What causes Trotter's triad?
Nasopharyngeal carcinoma invading laterally into the sinus of Morgagni
132
What structure pass through the gap formed between the base of the skull and the pharyngeal aponeurosis?
Sinus of Morgagni
133
What structures pass through the sinus of Morgagni?
Auditory tube
Levator veli palatine
Ascending palatine artery
Palatine branch of ascending pharyngeal artery
134
What structures pass through the gap formed between the super and middle constrictor muscles?
Glossopharyngeal nerve
Stylopharyngeus muscle
135
What structures pass through the gap formed between the middle and inferior constrictor muscle?
Internal laryngeal nerve
Superior Laryngeal vessels
136
What structures pass below the inferior constrictor muscle?
Inferior laryngeal nerve
Inferior laryngeal vessels
137
What is the function of the three longitudinal muscles of the pharynx?
Elevate pharynx and larynx during swallowing [shorten pharynx during swallowing and speaking]
138
What innervates the three longitudinal muscles?
Salpingopharynx + Palatpharynz = Vagal neve via pharyngeal plexus
Stylopharyngeus = glossopharyngeal nerve [CN 9]
139
Describe the clinical presentation of a patient presenting with Vagal nerve injury
Dysphagia
uvula will move to the contralateral side
Muscle of the soft palate will fall to raise ipsilateral to the injured nerve
140
What is the parasympathetic supply of the pharynx?
secreto-motor from facial nerve passing through lesser palatine nerve
141
What forms the pharyngeal nerve plexus?
Cranial part of accessory through pharyngeal branch of
vagus
Pharyngeal branch of glossopharyngeal nerve
Pharyngeal branch of superior cervical ganglion of sympathetic trunk lie on the middle constrictor m
142
What supplies sensory innervation to the pharynx?
Nasopharynx - Pharyngeal branch of CN5 V2 [maxillary division of trigeminal nerve]
Oropharynx- CN IX [glossopharyngeal]
Laryngopharynx- CN X [Internal branch of superior laryngeal nerve]
143
What are the layers of the pharynx from the inside to the outside?
Mucosa
Submucosa
Pharyngobasilar fascia [pharyngeal aponeurosis]
Overlapping Muscular layers
Buccopharyngeal fascia
144
What innervates the laryngopharynx?
Glossopharyngeal and Vagus nerves [sensory]
145
What structures are found on the lateral walls of the nasopharynx?
Pharyngeal opening of auditory tube
Tubal elevation
Tubal tonsils
Pharyngeal recess
Salpingopalatine fold [anteiorly]
Salpinopharyngeal fold [posteriorly]
146
Where are the tubal tonsils found?
In the submucosa covering the end of the auditory tube
147
What is the pharyngeal recess?
small depression in lateral wall behind the tubal elevation
148
What structures are found to deep to the lateral walls of the nasopharynx?
Tensor veli palatini
Levator veli palatini
Salpingopharyngeal
Pharyngobasilar fascia
149
What innervates the nasopharynx?
pharyngeal branch of pterygopalatine ganglion
150
What is mucosa of the nasopharynx lined by?
Ciliated columnar to pseudo stratified epithelium
151
What is the most common site of nasopharyngeal carcinoma?
Pharyngeal recess
152
What type of epithelium lines the oropharynx?
NKSS
153
What innervates the roof of the oropharynx?
Glossopharyngeal and Vagus nerves [same as laryngopharynx]
154
What forms the roof of the oropharynx?
Soft palate and Pharyngeal isthmus
155
What forms the floor of the oropharynx?
Posterior 1/3 of tongue
Area between tongue and anterior aspect of epiglottis
156
What forms the anterior wall of the oropharynx?
oropharyngeal isthmus/ mouth opening
157
What forms the posterior wall of the oropharynx?
Pharyngeal constrictor muscle [supported by body of C2 and Upper part of C3]
158
What forms the lateral walls of the oropharynx?
from anterior to posterior:
Palatoglossal arch
tonsillar fossa
Palatppharyngeal arch
159
What structures are found on the lateral surface of the palatine tonsils?
Tonsillar arteries
Internal carotid a.
External palatine vein
Para tonsillar vein
160
What are the tonsillar arteries?
facial
ascending palatine
ascending pharyngeal
lesser palatine
161
What structures are found on the medial surface of the palatine tonsils?
Tonsillar cavities [tonsillar crypts and Intratonsillar cleft/pits]
162
What are palatine tonsils?
Two lymphoid tissue masses found in the triangular sinus/palatine fossa, which is on the lateral wall of the oropharynx.
163
What covers the palatine tonsils?
covered by the mucous membrane with thickening on the lateral surface, the capsule and mucous tonsillar gland
164
What are the superior and inferior boundaries of the laryngopharnyx?
Superiorly: Upper border of epiglottic cartilage
Inferiorly: lower border of cricoid cartilage [C6]
165
What is a common site for lodging of foreign bodies?
Piriform fossa on the posterior larynx [lateral wall of laryngopharynx]
166
What passes through the piriform fossa?
internal laryngeal nerve
167
What forms the anterior wall of the laryngopharynx?
Inlet of the larynx and posterior surface of the larynx (cricoid cartilage and arytenoid cartilage)
168
What forms the posterior wall of the laryngopharynx?
Pharyngeal constrictor muscles and bodies of C3 –C6 cervical vertebrae
169
What forms the lateral walls of the laryngopharynx?
Thyroid cartilage and associated structures.
Piriform recess (Fossa) on each side of the posterior larynx
170
What arteries provide an additional supply to the posterior surface of the esophagus?
branches of upper short gastric arteries
reinforced by terminal arteries from the esophageal branches of the thoracic aorta
occasionally an ascending branch of the posterior gastric artery
171
Describe the path of the esophageal branches of the left gastric artery?
Ascend beneath the visceral peritoneum to
supply perforating branches to the intramural
and submucosal plexuses.
172
Describe the branching that gives off esophageal branches of left gastric artery
Esophageal branches of left gastric artery a branch of
celiac trunk and left inferior phrenic artery
173
Where do esophageal arteries arise from?
inferior thyroid
Thoracic aorta
intercostal arteries
phrenic
left gastric
174
Pharyngeal bursa??
Attachment of cranial end of Notocord;
Rarely cartilaginous tumor
Pharyngeal hypophysis (remnant of Rathke’s pouch of stomodeum
175
How long are the small intestines?
6-7m long
176
What is the terminal ileum?
Distal 30 cm of the ileum
177
Where are the Jejunum and Ileum found?
Jejunum is Proximal 2/5 and ileum is the distal 2/3 to the duodena-jejunal junction
178
Where is the the Gastroduodenal junction found?
at L1
179
What are the part of the duodenum and how long is each part?
1st part [5 cm]
2nd part [7.5 cm]
3rd part [10 cm]
4th part [2.5 cm]
180
What is the function of M cells?
Take up microorganism from lumen and discharge into intracellular space near CD4+ T lymphocytes
181
Where are M cells found?
Overlies Peyer's patch
182
Describe the structure of M cells?
Microfolds not microvilli
183
Where are intermediate cells found?
In the lower half of intestinel glands
184
What is the function of intermediate cells?
can convert into other types of cells
185
Where are Enteroendocrine cells found?
Concentrated at lower portion of intestinal glands
186
What is the function of Enteroendocrine cells?
secretes CCK, Secretin. GIP, Motilin, somatostatin and Histamine
187
What is the function of Paneth cells?
regulate normal bacterial flora of the small intestines [contain anti-bacterial enzymes- lysozyme and alfa-defensins]
188
Where are paneth cells found?
At the base of intestinal glands
189
What intestinal cells are found at the lower portion of glands?
Paneth cells
Enteroendocrine cells
Intermediate cells
190
What is the function of Goblet cells?
Secrete mucous
191
Describe the distribution of Goblet cells throughout the intestines?
incidence increases from duodenum to ileum
192
Describe the structure of goblet cells
Mucinogen granules accumulate in Golgi cisternae
193
Describe the structure of Paneth cells
Contain basophilic cytoplasm, supranuclear Golgi, and intensely acidophilic secretory granules (c.f.)
194
What cells are found in the lamina propria of the small intestines?
Plasma cells
Macrophages
Mast cells
195
What is the length of the rectum?
12 cm
196
What is the rectum?
last part of the large intestines that is a continuation of the sigmoid colon [at S3] and then continues as the Anal canal
197
Where is the rectum found?
in the true pelvis
198
What is the function of the rectum?
Temporary storage of feces
199
What features distinguishes the rectum from the colon?
No tenia coli
No sacculation
No omental appendices
200
What is tenia coli?
Thickening of longitudinal muscle layer
201
What are sacculations?
outwards pockets of gut wall
202
What are omental appendices?
fat-filled peritoneal pockets
203
What forms the base of the ischioanal fossae?
Skin and Fascia
204
What forms the apex of the ischioanal fossae?
Meeting of the medial and lateral walls
205
What forms the posterior boundaries of the ischioanal fossae?
Lower border of gluteus Maximus
Sacrotuberous ligament
206
What forms the anterior boundaries of the ischioanal fossae?
Posterior border of the Perineal membrane
Bodies of the Pubic bones [inferior to origin of puborectalis]
207
What is the main function of the large intestines?
Water absorption and feces storage
208
What forms the lateral wall of sischioanal fossae?
Vertical wall:
Ischium + overlapping inferior part of obturator interns covered with obturator fascia and obturator foramen
Medial surface of the ischial tuberosity below the attachment of the opt. fascia
209
What forms the sacral flexors of the rectum?
follows curve of sacrum and coccyx
210
What forms the anorectal flexure of the rectum?
formed by Tone of puborectalis muscle
211
What significantly contributes to fecal continence?
tone of puborectalis muscle
212
What are the permanent mucosal folds in the rectum?
Superior, Middle and Inferior transverse rectal folds
213
What type of curvatures are seen in the rectum?
3 lateral curvatures
Anteroposterior curvate [concavity anteriorly]
214
What lateral curvatures are seen in the recum?
3 lateral curvatures [2 towards the left and 1 towards the right] LRL
215
What supports the ampulla of the rectum?
Levator ani muscle
216
What is the ampulla of the recum?
Final segment of rectum that is located between the middle and inferior flexures. It is continuous with the anal canal.
217
What is the function of the ampulla of the recum?
Relaxes and expands to accumulate and temporarily stores feces until defecation occurs
218
What structures are found anterior to the rectum in males?
Sigmoid colon
Ileum
Fundus of urinary bladder
Lower parts of ureters
Ductus Deferens
Seminal vesicles
Prostate glands
219
What structures are found anterior to the rectum in females?
Sigmoid colon
Ileum
Lower part of the Uterus
Vagina
Urinary bladder
Lower parts of ureters
220
What does the rectovesical septum separate?
Found in males between the fundus of the bladder and Ampulla of the rectum
221
What does the rectouterine pouch separate?
Found in females between the posterior part of the fornix and the cervix
222
What structures are found posterior to the rectum?
Lies against inferior 3 sacral vertebra + coccyx
Piriformis muscles
Coccygeus muscles
Levator ani muscles
Anococcygeal ligament
Median sacral vessels
Inferior end of sympathetic trunks
Sacral plexus and nerves
223
What artery supplies the proximal part of the rectum?
Superior rectal artery
224
What artery supplies the middle and inferior parts of the rectum?
Middle rectal artery
225
What artery lies posterior to the rectum?
Median sacral artery
226
What artery supplies the anorectal junctions and anal canals?
Inferior rectal artery
227
What artery does the median sacral artery branch off of?
Aorta [direct branch]
228
What artery does the inferior rectal artery branch off of?
inferior pudendal arteries
229
What artery does the middle rectal artery branch off of?
Internal iliac arteries
230
What artery does the superior rectal artery branch off of?
Continuation of inferior mesenteric artery
231
What is mainly responsible for the venous drainage of the rectum?
through rectal venous plexus
232
Where does the superior rectal vein drain into?
Superior rectal vein → portal venous system
233
Where do the middle and inferior rectal veins drain into?
→ internal iliac vein → IVC
234
Where does the median sacral vein drains into?
→ internal iliac veins
235
What is a portocaval anastomosis in female [rectum]
In the wall of the anal canal:
Uterovaginal plexus
236
What is a rectal portocaval anastomosis in males?
In the wall of the anal canal:
Vesical plexus
237
What are the two part of the rectal plexus? Where are they found?
Internal rectal venous plexus [deep to mucosa]
External rectal venous plexus [external to muscular wall of anal canal]
238
What provides sympathetic innervation to the rectum?
Lumbar splanchnic nerve
Sacral splanchnic nerves
239
What arteries and nerves form the periarterial plexus found in the rectym?
Postganglionic fibers of the sacral splanchnic nerves
Inferior mesenteric artery
Superior rectal artery
240
What is the role of the sympathetic supply to the rectum?
inhibitory to colonic muscles
241
What provides parasympathetic supply to the rectum?
S2-S4 via pelvic splanchnic nerve to inferior hypogastric plexus
242
What is the role of the parasympathetic supply to the rectum?
Postganglionic neurons innervate glands and muscles
243
What is the role of the visceral afferent fibers to the rectum?
conveys sensation of rectal filings
involved in reflection propulsive activity
244
What provides visceral afferent fibers to the rectum?
parasympathetic fibers retrogradely to sacral dorsal root ganglia (mostly S1 and S2)
245
describe the lymphatic drainage of the lower rectum
→ internal iliac nodes [follows internal rectal a.] → presacral nodes [follows median sacral a.]
246
Describe the lymphatic drain of the rectum and anal canal / above dentate line
Intramural lymph → pararectal nodes → lymphatics along superior rectal artery → lymphatics along inferior mesenteric artery → pre-aortic nodes
247
What structures can be palpated anteriorly in a digital rectal exam?
Cervix [f]
Prostate + Seminal vesicle [m]
248
What structures can be palpated posteriorly in a digital rectal exam?
Sacrum
Coccyx
249
What cells line the epithelium of the rectum?
Simple columnar epithelium
250
How long is the anal canal?
2.5-3.5 cm
251
What is the anal canal?
Terminal portion of the large intestines that lies in the perineum and extends from the superior aspect of the pelvic diaphragm to the anus. It remains collapsed, except during passage of feces
252
What two structures surround the anal canal?
Internal and External anal sphincters
253
What is the anus?
external outlet of the alimentary tract
254
Describe the structure of the anal canal?
Begins at anorectal junction, then descends posteroinferiorly between the anococcygeal ligament and the perineal body and ends at the anus
255
What is the anorectal junction?
Rectal ampulla narrows as the level of the u-shaped sling formed by the puborectalis muscle
256
What muscle forms the anorectal junction?
Puborectalis muscle
257
What structure is found posterior to the anal canal?
Anococcygeal ligament
258
What structure is found lateral to the anal canal?
Ischioanal fossae
259
What is the function of ischioanal fossae?
supports the pelvic viscera and allows distension of anal canal during defecation
260
What structures pass through the ischioanal fossa?
inferior rectal vessels and nerves
261
What structures are related to the anal canal inferiorly?
Perianal fat
262
What structures are related to the anal canal anteriorly in males?
Perineal body
Urogenital diaphragm
Membranous part of urethra
Bulb of penis
263
What structures are related anteriorly to the anal canal in females?
Perianal body
Urogenital diaphragm
Lower part of vagina
264
What is the perineal body?
Fibromuscular structure that serves as attachment for several msucles
265
Which of the anal sphincters is voluntary and involuntary?
Internal → involuntary
External → voluntary
266
Which parts of the anal canal does the internal anal sphincter surround?
Superior 2/3 of anal canal
267
Which parts of the anal canal does the external anal sphincter surround?
Inferior 2/3 of anal canal
268
What are the three part of the external anal sphincter?
Deep
Superficial
Subcutaneous
269
What are the anterior and posterior attachments of the external anal sphincter?
Anterior : perineal body
Posterior: coccyx via anococcygeal ligament
270
Relation of the external anal sphincter and puborectalis
E. anal sphincter blends superiorly with puborectalis
271
What are the other names of the pectinate line?
Dentate line
Mucocutaneous junction
272
What is the pectinate line?
Inferior comb-shaped limit of the anal valves forms an irregular line indicates the junction of superior part of anal canal and inferior part
273
What is the significance of pectinate line?
Demarcates superior visceral endodermal hindgut and inferior somatic proctoderm ectodermal parts of anal canal.
274
What is the anorectal junction?
the point where the wide rectal ampulla abruptly narrows as it traverses pelvic diaphragm,
275
What demarcates the anorectal junction?
it is indicated by the superior ends of anal columns where the rectum joins the anal canal
276
What is the anal verge?
junction on the outside of the anus of hair-bearing and non hair-bearing skin
277
What is Hiltons' white line?
anocutaneous intersphincteric groove indicates the line of attachment of perianal fascia externally.
278
What are anal columns?
series of mucosal longitudinal ridges extending from the anorectal junction in the superior half of the anal canal,
279
What structures are contained in the anal columns?
Superior rectal arteries and veins
280
Where are anal valves found?
Inferior end of the anal column
281
What are anal sinuses?
Small recesses where ducts of mucous anal glands open. It is found superior to the valves into
282
What role does anal sinuses play in defecation?
When compressed by feces, anal sinuses exude mucus, which aids in evacuation of feces from anal canal
283
What artery supplies the upper part of the anal canal?
Superior rectal artery [continuation of the inferior mesenteric artery]
284
What artery supplies the lower part of the anal canal?
Inferior rectal artery [branch of internal pudendal artery]
285
What forms the recto-uterine pouch?
Peritoneal reflection from the rectum to the posterior part of the fornix of the vagina
286
What forms the rectovesical pouch?
Peritoneal reflection from the rectum to the posterior wall of the fundus of the bladder
287
How does the peritoneum cover the upper 1/3 of the rectum?
Covered on the anterolateral aspect
288
How does the peritoneum cover the middle 1/3 of the rectum?
Anteriorly only
289
How does the peritoneum cover the lower 1/3 of the recum?
Not covered below the peritoneal reflection
290
What is the pararectal fossa?
found on the upper 1/3 of the rectum as its covered anterolaterally by the peritoneum
291
What is the pudendal canal?
fascia enclosed on the internal pudendal vessels and nerves in the lateral wall
292
What structures are found in the fat bodies in the ischianal fossa?
Inferior rectal vessels and nerves
Perforating branch of S2 and S3
Perineal branch of S4
Postscrotal nerves and vessels
293
What is the surgical significance of the ischioanal fossa?
an important plane during resections of the anal canal and anorectal junction for malignancy [bloodless].
It encompasses all of the muscular structures of the anal canal and leads to the inferior surface of levator ani, through which the dissection is carried
294
What is the role of Internal anal sphincter in defecation?
Parasympathetic fibers via pelvic splanchnic nerves inhibits its contraction, thus relaxes the sphincter, opening the anal canal
295
What are the three major gross differences between the small and large intestines?
Omental appendices
Haustrations
Teniae coli
296
When is the cecum palpable?
When its distended with either feces or gas
297
Attachment of the cecum
No mesentery, but maybe attached to the lateral abdominal wall by cecal folds
298
What is the function of the Enteric nervous system?
Responsible for enteric reflex
Peristalsis
Maintain functional integrity of the gut
299
What is the effect of sympathetic and parasympathetic denervation on the GIT?
Transiently effects gut motility
300
Describe Enteric excitatory neurons
Projects in oral directions
ACh and Substance P as a cotransmitter
301
Describe Enteric Inhibitory neurons
Projects in Anal direction
ATP [in intestines] and VIP [in stomach], with NO as a cotransmitter
302
What are the two types of intrinsic motor neurons?
Enteric excitatory and inhibitory neurons
303
What triggers the impulses from intrinsic sensory neurons in peristalsis reflex?
stretching of the gut
chemical stimulation of sensory endings in mucosa
