Anatomy 🫀 Flashcards
1
Q
What forms the thoracic cage?
A
is formed of:
• 12 vertebrae (posteriorly)
• 12 pairs of ribs
• Sternum (anteriorly).
2
Q
What are ribs classified according to?
A
Ribs are divided according to extent into:
- True ribs: upper 7 (reach the sternum)
- False ribs: lower 5 subdivided into:
1. Vertebrochondral: from 8 to 10 ribs
2. Floating: 11 & 12 ribs
Ribs can be divided according to (structure) into:
- Typical ribs: from 3 to 9.
- Atypical ribs: 1 - 2 - 10 - 11 - 12.
3
Q
What does each typical rib and the second rib articulate with?
A
Each typical rib + (2nd rib) articulate with vertebra of the same level & vertebra above
4
Q
What is the neck of the first rib related to?
A
is related to (N.A.N):
1. sympathetic trunk
2. superior intercostal artery
3. branch from 1st intercostal nerve
5
Q
What does the coastal groove on inner surface of ribs contain?
A
- intercostal vessels & nerve (arranged as Vein. Artery.
Nerve from above downwards)
6
Q
What are thoracic vertebrae classified into?
A
Thoracic vertebrae are divided into:
- typical: 2 to 8
- Atypical: 1-9-10-11-12
7
Q
what forms the thoracic wall?
A
- It is formed of 12 pairs of ribs & 11 intercostal spaces.
- spaces contain: muscles, vessels, nerves & lymphatics
8
Q
What are the layers of intercostal muscles?
A
1) External intercostal muscles.
2) Internal intercostal muscles.
3) Transversus Thoracis: Divided into 3 parts:
a) Subcostalis.
b) innermost intercostal (Intercostals intimi)
c) Sternocostalis
9
Q
What is the origin, insertion, direction, extant, completed by, nerve and action of external intercostal muscles?
A
Origin: rib above
Insertion: rib below
Direction: Downward & forward.
Extent: From tubercle of rib posteriorly to costochondral
junction (in front).
Completed by: Continued anteriorly as anterior intercostal membrane
Nerve: Corresponding intercostal nerve
Action: Inspiration (Elevation of ribs)
10
Q
What is the origin, insertion, direction, extant, completed by, nerve and action of internal intercostal muscles?
A
Origin: rib above
Insertion: rib below
Direction: Downward & forward.
Extent: From lateral margin of sternum till angle of rib
Completed by: Posterior intercostal membrane
Nerve: Corresponding intercostal nerve
Action: Depression of ribs (expiration)
11
Q
What is the origin, insertion, direction, extant, completed by, nerve and action of innermost intercostal muscles?.
A
Origin: rib above
Insertion: rib below
Direction: Downward & backward
Extent: attached between the rib above and the rib below
Nerve: Corresponding intercostal nerve
Action: Depression of ribs (expiration)
12
Q
What is the origin, insertion, direction, extant, completed by, nerve and action of subcostalis muscle?
A
Origin: Inner surface of one rib medial to the angle
Insertion: Inner surface of the 2nd or 3rd rib below
Direction: down & medially
Site: posterior of the intercostal space
Nerve: Intercostal nerves.
Action: Depression of the ribs during expiration
13
Q
What is the origin, insertion, direction, extant, completed by, nerve and action of sternocostalis muscles?
A
Origin: Back of the lower part of the body of the sternum and xiphoid process
Insertion: Inner surface of costal cartilages from 2nd to 6th
Direction: up & laterally
Site: Anterior of the intercostal space
Nerve: Intercostal nerves.
Action: Depression of the ribs during expiration
14
Q
What is the definition of intercostal nerves?
A
ventral rami of upper 11 thoracic spinal nerves (12th = subcostal, below last rib)
15
Q
What is the number of intercostal nerves?
A
11, pass in corresponding intercostal spaces.
16
Q
What are the types of intercostal nerves?
A
- Typical: from third to sixth as they are distributed, only, in chest
- Atypical: upper 2 & last 5 intercostal nerves
17
Q
What are the branches of typical intercostal nerves?
A
1) Rami communicates with sympathetic trunk:
A. It gives a white myelinated ramus communicans (preganglionic) to sympathetic trunk.
B. It receives gray unmyelinated ramus communicans (postganglionic) from the ganglion
2) Muscular branches: to intercostal muscles
3) Collateral branch: Runs along upper border of rib below & Supplies intercostal muscles.
4) Lateral cutaneous branch: Supplies skin on lateral side of chest.
5) Anterior cutaneous branch: Supplies skin on front of chest.
6) Pleural branches: Sensory to parietal pleura
18
Q
What do atypical intercostal nerves supply?
A
- 1st intercostal nerve: supplies upper limb
- 2nd intercostal nerve: supplies axilla skin
- Lower five intercostal nerves: They supply skin & muscles of anterior abdominal Wall.
- The 12th thoracic nerve is called subcostal nerve
19
Q
What is the number, location, origin and termination of anterior intercoastal arteries?
A
Number: 2 in each space
Location: In upper 9 intercostal spaces
Origin:
1-6: from internal thoracic artery
7-9: from musculophrenic artery
Termination:
Upper anterior: anastomoses with posterior intercostal artery itself.
Lower anterior: anastomoses with collateral branch of posterior intercostal artery
20
Q
What is the number, location, origin and termination of posterior intercoastal arteries?
“The posterior intercostal arteries give Branches that Anastomose with internal thoracic artery”
A
Number: 1 in each space
Location: In all intercostal spaces (11 spaces)
Origin:
1 & 2: from superior intercostal artery “SICA” “from subclavian”
- 3-11: from descending thoracic artery
Termination:
Upper anterior: anastomoses with posterior intercostal artery itself.
Lower anterior: anastomoses with collateral branch of posterior intercostal artery
21
Q
What is the number, location, termination and final termination of anterior intercoastal veins?
A
Number: 2 in each space
Location: in upper 9 spaces
Termination:
1-6: internal thoracic vein “beside internal thoracic artery”
7-9: vena comitantes of musculophrenic artery
Final Termination:
Internal intercostal vein terminates in the corresponding brachiocephalic vein.
22
Q
What is the number, location, termination and final termination of posterior intercoastal veins?
A
Number: 1 in each space
Location: In all intercostal spaces
Termination:
- Right side:-
1st: Rt brachiocephalic vein
2-3: unite to form Rt superior intercostal vein which end into azygos vein. “The arch”
4-11: azygos vein.
- Left side:-
1st: Lt brachiocephalic vein
2-3: unite to form Lt superior intercostal vein which end into Lt brachiocephalic vein.
4-8: superior hemiazygos vein. 9-11: inferior hemiazygos vein.
Final Termination:
Right side: Azygos vein terminates into superior vena cava (sternal angle).
Left side: Hemiazygos veins terminate into azygos vein opposite T8.
23
Q
What is the origin of azygos vein?
A
o Common: from the back of I.V.C
o Rare: union of Rt ascending lumbar vein & Rt subcostal vein
24
Q
What is the termination of azygos vein?
A
In the S.V.C at the level of the sternal angle.
25
What are the tributaries of azygos vain?
- Rt ascending lumbar vein.
- Subcostal vein.
- Rt posterior intercostal veins (4-11).
- Rt superior intercostal vein
- Rt bronchial veins.
- Esophageal veins.
- Pericardial veins.
- Superior & inferior hemiazygos.
26
What is the origin of the diaphragm?
I. Sternal origin: Inner aspect of xiphoid process
II. Costal origin: lower 6 ribs (inner surface)
III. Vertebral origin:
• left crus: L1 & L2 vertebrae
• right crus: L1.2,3 vertebrae
• median arcuate ligament (Between the 2 crura)
• medial arcuate ligament (From crus to L1 transverse process) lateral arcuate ligament (From L1 transverse process to last rib)
27
What is the insertion of the diaphragm?
central tendon
28
What is the nerve supply of the diaphragm?
phrenic nerve (C3, 4, 5).
29
What are the major foramina in the diaphragm?
Aortic, esophageal, vena caval
30
What is the site, level and transmit of vena caval foramin?
- to the right of midline in central tendon
- T8
- IVC, Right phrenic nerve
31
What is the site, level and transmit of esophegeal foramin?
- to the left of midline inside right crus.
- T10
- Esophegus, 2 vagi (gastric nerves)
32
What is the site, level and transmit of aortic foramin?
- midline, deep to median actuate ligament
- T12
- aorta,azygous and thoracic duct
33
What are the bones forming in the lateral wall of the nose?
1. Maxilla.
2. Lacrimalbone.
3. Ethmoid bone.
4. Palatine bone.
5. Sphenoid bone.
6. Inferior nasal concha.
34
What are nasal conchae?
Conchae is shelf-like projections from the lateral wall of the nose. "Covered by mucous membrane"
35
What are examples of nasal conchae in the lateral wall of the nose?
• Superior nasal concha→part of ethmoid bone.
• Middle nasal concha→part of ethomid bone.
• Inferior nasal concha→separate bone.
36
What do nasal conchae divide the nasal cavity into?
The 3 conchae divide the nasal cavity into 4 spaces:
• Spheno- ethmoidal recess→above superior concha.
• Superior meatus→below the superior concha.
• Middle meatus→below the middle concha.
• Inferior meatus→below the inferior concha.
37
What are the openings in the lateral wall of the nose?
1. Spheno-ethmoidal recess: receive opening of sphenoidalsinus.
2. Superior meatus: receive opening of posterior ethmoidalsinus.
3. Middle meatus: receive the opening of
Middle ethmoidal sinus (opens on bulla ethmoidal)
Frontal sinus, anterior ethmoidal sinus & maxillary sinus (open on hiatus semilunaris)
4. Inferior meatus: receive opening of nasolacrimal duct. "That's why we feel the taste of "قطرة"
38
What are the paranasal sinuses and where do they open?
• Are cavities filled with air within the skull bones.
• They open in the lateral wall of the nose.
39
What is the number of paranasal sinuses?
• There are 4 paranasal sinuses on each side of the nose: frontal,ethmoidal, sphenoidal & maxillary.
40
Where do frontal sinuses open?
- Opens in the hiatus semilunaris in the middle meatus through the frontonasal duct (infundibulum).
41
Where do ethmoid sinuses open?
❖ Posterior ethmoidal sinuses open in the superior meatus.
❖ Middle ethmoidal sinuses open in the bulla of ethmoid in the middle meatus.
❖ Anterior ethmoidal sinuses open in the hiatus semilunaris in the middle
meatus.
42
Where do maxillary sinuses open?
❖ Opens in the hiatus semilunaris in the middle meatus.
43
Where do sphenoidal sinuses open?
❖ Opens in sphenoethmoidal recess.
44
What is the arterial supply of the nose?
➢ From ophthalmic artery:
1. Anterior ethmoidal artery.
2. Posterior ethmoidal artery.
➢ From maxillary artery:
1. Sphenopalatine artery "the main artery of the nose"
2. Greater palatine artery
➢ From facial artery :
1. Lateral nasal artery
2. Septal branch of superior labial artery.
45
What is the site of the little area of epistaxis?
- anteroinferior part of nasal septum.
46
What is the little area of epistaxes formed from?
Anastomosis of 3 arteries:
a. Anterior ethmoidal artery.
b. Sphenopalatine.
c. Septal branch of superior labial.
47
What is the nerve supply to the lateral wall of the Nose?
Skin of the nose:
a. Infraorbital nerve.
b. Infratrochlearnerve.
c. External nasal nerve.
Nasal Septum:
a. The roof: olfactory nerves.
b. Anterior part: anterior ethmoidal nerve.
c. Remaining: nasopalatine nerve.
Lateral wall:
a. The roof: olfactory nerve.
b. Anterior: anterior ethmoidal nerve.
c. Remaining: sphenopalatine & greater palatine nerves
"The nerve supply for both the roof and anterior part of the nasal septum and the lateral wall are common"
48
What are the parts of the pharynx? And where do they lie?
The pharynx is divided in to 3 parts:
• Nasal part (nasopharynx) → behind nasal cavity.
• Oral part (oropharynx) → behind oral cavity.
• Laryngeal part (laryngopharynx) → behind laryngeal cavity.
49
What are the boundaries of the nasopharynx?
Superior: base of skull.
Inferior: communicates with oropharynx
(through pharyngeal isthmus).
Anterior: nasal cavity.
Posterior: base of skull & atlas (C1). Laterally: superior constrictor muscle.
50
What are the characters in the nasopharynx?
1. Opening of the auditory tube. "To middle ear"
2. Tubal elevation: above & behind auditory tube.
3. Salpingopharyngeal fold: extends from auditory tube.
4. Pharyngeal recess: vertical groove behind the salpingopharyngeal fold.
5. Pharyngealtonsil (adenoid).
51
What are the boundaries of the oropharynx?
❖ Superior: nasopharynx.
❖ Inferior: laryngopharynx.
❖ Anterior: communicates with oral cavity (through oropharyngeal isthmus).
❖ Posterior: C2, 3 vertebrae.
❖ Laterally: superior & middle constrictor muscles.
52
What are the characters in the oropharynx?
❖ Palatine tonsil: lies between palatoglossal fold anteriorly & palatopharyngeal fold posteriorly.
"Inflammation in the Palatine tonsil causes its enlargement leading to obstruction to the oral cavity and difficulties in swallowing, so when you notice white points in the palatine tonsil, intravenous administration of antibacterial is recommended"
53
What are the boundaries in the laryngopharynx?
❖ Superior: oropharynx.
❖ Inferior: continues as esophagus at lower border of C 6.
❖ Anterior: laryngeal cavity.
❖ Posterior: C 4, 5 & 6.
❖ Laterally: middle & inferior constrictor muscles.
54
What is the origin of superior constrictor muscles?
1. Medial pterygoid plate.
2. Pterygoid hamulus.
3. Pterygomandibular raphe.
4. Mylohyoid ridge.
55
What is the insertion of superior constrictor muscle?
pharyngeal tubercle & pharyngeal raphe.
56
What is the action of the superior constrictor muscle?
Helps to close off the nasopharynx during swallowing.
57
What is the origin of the middle constrictor Muscle?
Hyoid bone & stylohyoid ligament.
58
What is the insertion of the middle constictor muscle?
pharyngeal raphe.
59
What is the action of the middle constrictor muscle?
- Constriction of oropharynx during swallowing.
60
What is the origin of the inferior constrictor muscle?
1. Thyroid cartilage.
2. Cricoid cartilage
61
What is the insertion of the Inferior constrictor Muscle?
Pharyngeal raphe
62
What is the action of the inferior constrictor muscle?
- Constriction of laryngopharynx during swallowing.
63
What are the longitudinal muscles of the pharynx?
1. Salpingopharyngeus
2. Palatopharyngeus
3. Stylopharyngeus
64
What is the nerve supply of the pharynx?
Motor:
❖ All muscles of the pharynx supplied by pharyngeal plexus (accessory nerve through the vagus nerve) except stylopharyngeus supplied by glossopharyngeal nerve.
Sensory: (5-9-10)
❖ Nasopharynx: maxillary nerve.
❖ Oropharynx: glossopharyngeal nerve.
❖ Laryngopharynx: vagus nerve.
Autonomic:
❖ Sympathetic: superior cervical sympathetic ganglion.
❖ Parasympathetic: facial nerve.
65
What is arterial supply of the pharynx?
❖ Ascending pharyngeal (from the external carotid artery).
❖ Ascending palatine & tonsillar "main artery supplying the palatine tonsil" (from the facial artery). "Branch from ECA"
❖ Greater palatine & pharyngeal (from the maxillary artery).
❖ Superior and inferior laryngeal.
❖ Dorsal lingual (from the lingual artery).
66
What is the Larynx composed of?
- The larynx is composed of cartilages that prevents collapse of the airway. “ Not like the Pharynx and Esophegus”
67
What are the Cartilages of the larynx connected together by?
membranes & muscle fibers.
68
What are examples of laryngeal cartilages?
❖ single: thyroid, cricoid, and epiglottis.
❖ Paired: arytenoid, corniculate & cuneiform. “Appear internallly”
69
what are the characteristics of thyroid cartilage?
it has:
❖ Superior horn, Oblique line & Inferior horn
❖ The superior horn attached by a ligament to the hyoid bone
❖ The inferior horn articulates with the cricoid cartilage.
70
What are the characteristics of the cricoid cartilage? “ The most important Cartilage”
❖ It consists of a large posterior lamina & narrow anterior arch (a signet ring appearance).
71
What are the characteristics of the epiglottis Cartilage?
❖ Thin leaf –like fibrocartilage.
❖ lower end is tapering and attached to the inner surface of thyroid cartilage by thyroepiglottic ligament.
72
What are the characteristics of arteynoid cartilage?
❖ They are pyramidal in shape.
❖ The base has 2 processses; muscular process
laterally and vocal process anteriorly
73
What is the site of corniculate Cartilages?
Lies in the aryepiglotic fold.
74
What are the characteristics of cuneiform cartilages?
A small cartilage lies in the aryepiglotic fold.
75
What is the extent of the thyrohyoid membrane?
Extends from the upper border of the thyroid cartilage to inner “not lower” surface of the hyoid bone.
76
What is the thyrohyoid membrane pierced by?
It has a hole pierced by the:
▪ Internal laryngeal nerve: from the superior laryngeal nerve.
▪ Superior laryngeal artery: from the superior thyroid artery.
77
What is the extent of the medium cricothyroid membrane?
- from cricoid to thyroid cartilage in the midline.
78
What is the extent of the cricotracheal membrane?
- cricoid to the 1st tracheal ring.
79
What are the external membranes of the larynx?
- Thyrohyoid membrane, median cricothyroid membrane and Cricotracheal membrane
80
What are the internal membranes of the larynx?
- Quadrangular membrane and cricovocal membrane
81
What is the extent of the quadrangular membrane?
- It extends between the arytenoid cartilage & the epiglottis
82
What folds does the quadrangular membrane form?
❖ It forms 2 folds:
▪ The free upper border forms the aryepiglottic fold.
▪ The free lower border forms the vestibular fold.
83
What is the space between the aryepiglottic fold and vestibular folds called?
Vestibule
84
What is the extent of the cricovocal ligament (membrane)?
- Extends between cricoid, thyroid & vocal process of the aryetnoid.
85
What does the free upper border of the cricovocal membrane form?
- Its free upper border forms the vocal cord (vocal ligament).
86
What is the inlet of the larynx?
- It is the communication between the pharynx & the larynx.
87
What are the boundaries of the inlet of the larynx?
- It is bounded by:
a. Anteriorly: epiglottis.
b. Posteriorly: arytenoid & interaryetnoid fold.
c. On each side: aryepiglottic fold.
88
What is the pisiform fossa and what is its site?
- Piriform fossa is the space on each side of the laryngeal inlet.
89
What is the extent of the laryngeal cavity?
- It extends from the upper border of the epiglottis above to the lower border of the cricoid cartilage below.
90
What are the parts of the laryngeal cavity?
Vestibule
Sinus
Infraglottic cavity
91
What is the extent of the vestibule of the laryngeal cavity?
❖ It lies between the laryngeal inlet above to the vestibular folds below.
92
What is the extent of the sinus of the laryngeal cavity?
- It lies between the vestibular folds above to the vocal folds below.
93
What are the characteristics found in the sinus of the laryngeal cavity?
❖ The space between the 2 vestibular folds is called rima vestibuli.
❖ The space between the 2 vocal folds is called rima glottidis. "The narrowest point"
94
What is the extent of the infraglottic cavity of the laryngeal cavity?
❖ It lies between the vocal folds above & the lower border of the cricoid cartilage below.
❖ It leads to the cavity of the trachea.
95
What are the muscles that move the larynx?
- Extrinsic muscles and intrinsic muscles
96
What are the extrinsic muscles Of the larynx and what are their functions?
- Their function is to move the larynx up and down "during eating"
- Elevators like suprahyoid muscles
- Depressors like infrahyoid muscles
97
What do intrinsic muscles of the laryngeal cavity act on?
- There are muscles that act on the laryngeal inlet and other muscles that act on the vocal cords.
98
What are the intrinsic muscles acting on the laryngeal Inlet?
- Open the laryngeal inlet (inhalation): thyroepiglottic. Closing (sphincter) (swallowing): aryepiglottic.
99
What are the intrinsic muscles acting on the vocal cords?
- Abduction: posterior cricoarytenoid muscle (open rima glottides) Most important ms. (it is ms. of life).
- Adduction: two muscles:
a. Lateral cricoarytenoid.
b. Transverse arytenoid.
- Tensor or elongation: cricothyroid muscle.
- Relaxing or shortening: two muscles
a. Thyroaryetnoid.
b. Vocalis (upper part of thyroaryetnoid).
100
What is the motor nerve supply of the laryngeal cavity?
❖ All intrinsic muscles of the larynx supplied by the recurrent laryngeal nerve.
❖ Except cricothyroid muscle supplied by external laryngeal nerve.
101
What is the sensory nerve supply of the laryngeal cavity?
❖ Above the level of vocal fold supplied by internal laryngeal nerve.
❖ Below the level of the vocal folds supplied by the recurrent laryngeal nerve.
102
What is the definition of the trachea?
- Fibro-muscular tube that conveys the air into & out of the lungs.
103
What are the dimensions of the trachea?
11 cm long, 2.5 cm in diameter.
104
What is the beginning course and termination of the truchea?
- Continuation of the larynx at the lower border of the 6th cervical vertebra (opposite the lower border of the cricoid cartilage). "Also the esophagus starts from the pharynx and this level"
- Course:
• The upper half of the trachea lies in the neck (cervical part) & the lower half lies in the chest (thoracic part).
• The trachea lies in the median plane for most of its course, but at its lower part it deviates to the right side.
- Termination (carina): Ends at the level of the sternal angle by dividing into right & left bronchi.
105
What are the relations of the trachea?
- Anteriorly:
➢ Thyroid gland.
➢ Arch of the aorta & its branches
- Posteriorly: Esophagus
106
Compare between the right bronchus and list to bronchus according to
Length
width
Straightness
Level of entering the hilum
Time of division
Length: Shorter 1 inch - Longer 2 inches
Width:, Wider - Narrower. -,.
Straightness: More vertical i.e in line with the trachea. - Oblique, deviates laterally from the trachea.
Level of entering the hilum: Enters the hilum oppositeT5 -
Enters the hilum opposite T6.
Time of division: Divides before entering into the lung - Divides after entering into the lung.
107
When does the respiratory system start its development? And what does it start as?
- during the 4th week "nearly as the heart" as a respiratory diverticulum (lung bud), which appears as an outgrowth from the ventral wall of the foregut.
108
What separates the lung bud from the foregut? And what happens after that?
- Two longitudinal ridges called Tracheoesophageal ridges separate the lung bud from the foregut. These ridges fuse together forming tracheoesophageal septum which divides the foregut into 2 parts:
1. Ventral part: laryngo-tracheal tube. "Resp. Diverticulum"
2. Dorsal part: oesophagus.
109
What happens to the Laryngo-tracheal tube?
-The upper part of the laryngo-tracheal tube gives the larynx. Then it elongates to form the trachea. Its caudal end divides giving the right and left principal bronchi.
110
What happens to the right and left bronchi?
• The right bronchus divides into 3 secondary bronchi which later on divide to give 10 tertiary (segmental) bronchi.
• The left bronchus divides into 2 secondary bronchi which later on divide to give 8 – 10 tertiary (segmental) bronchi.
• The segmental bronchi will form the bronchopulmonary segments of the adult lung.
• The segmental bronchi divide up to 17 times (before birth) giving bronchioles.
• Additional 6 divisions occur after birth till the age of 8 years.
111
What is the origin of the epithelial lining of the respiratory system?
- The epithelium lining of the respiratory system is endodermal in origin (except the nose is ectodermal)
112
What is the origin of the muscles, Cartilages and the connective tissue of the respiratory system?
- splanchnic (visceral) layer of lateral plate mesodermal.
"General rule"
113
What happened to the lining epithelium of the respiratory system?
- Proliferation of the lining epithelium obliterates the lumen then recanalization occurs.
114
What are the stages, time and events of lung maturation?
1.Pseudoglandular:
1st - 4th month.
- Repeated divisions to form bronchi and terminal bronchioles.
- The lung resembles an exocrine gland.
2. Canalicular:
4th - 6th month.
- Each terminal bronchiole divides into 2 respiratory bronchioles which divide into 4- 6 alveolar ducts.
"The capillaries are nearer"
3. Terminal sac:
6th month – birth.
- Primitive alveoli (alveolar sac) are formed and capillaries establish close contact.
"Lined with type I & II Pnemocytes"
4. Alveolar: "longest"
8th month - 8 years.
- Mature alveoli "only after birth" have well-developed epithelial endothelial (capillary) contacts. "
115
What are the types of cells in the alveoli?
➢ Type I pneumocytes: represent the main lining of the alveoli.
➢ Type II pneumocytes: secrete pulmonary surfactant
116
When does surfactant production begin and when is sufficient amount of surfactant present?
• Surfactant production begins at 20 - 22 weeks. "5th month"
• At 26 – 28 "7th month" weeks sufficient amount of surfactant is present. So, if the fetus is born at the end of terminal sac period he can survive if given a special care.
117
What should be given to women with expected preterm labor?
- Women who expected to have preterm labor are given glucocorticoids because it increases the production of surfactant. "Preterm = before 8th month”
118
What forms the visceral pleura?
The mesoderm which covers the lung
119
What forms the parietal pleura?
The mesoderm which lines the body wall
120
What forms the pleural cavity?
Space between the parietal and visceral pleura
121
What are the steps of the formation of the pleura?
• The lung buds expand into the pericardioperitoneal canals (which lie on each side of the foregut and are gradually filled by the expanding lung buds).
• The pleuroperitoneal and pleuropericardial folds separate the primitive pleural cavities from the peritoneal and pericardial cavities.
• The mesoderm which covers the lung forms the visceral pleura. "Visceral - splanchic"
• The mesoderm which lines the body wall forms the parietal pleura. "Partial mesoderm"
• Space between the parietal and visceral pleura is the pleural cavity.
122
What are the congenital anomalies of respiratory system?
1. Respiratory distress syndrome (hyaline membrane disease)
2. Ectopic lung lobes
3. Congenital cysts of the lung
4. Laryngomalacia
5. Tracheomalacia
6. Esophageal atresia with or without trachea-esophageal fistula
123
What is the cause of respiratory distress syndrome?
decreased amount of surfactant.
124
What are the features of respiratory distress syndrome?
failure of the alveoli to ventilate adequately.
125
What is the cause of ectopic lung lobes?
may be due to additional respiratory buds arising from the foregut.
126
What are the features of ectopic lung lobes?
the ectopic lung lobe may arise from the trachea or esophagus.
127
What are the features of congenital cysts of the lung?
dilatation of the terminal bronchiole with formation of multiple lung cysts. "Have no ability of ventilation"
128
What is the cause of laryngomalacia?
soft immature cartilages of the larynx.
129
What are the features of laryngomalacia?
"The common cause of stridor". 'شهقة"
laryngeal cartilages collapse inwards during respiration. It is the most common cause of chronic stridor in infancy.
130
What are the features of tracheomalacia?
soft tracheal cartilages that collapse during respiration.
131
What is the cause of esophageal atresia?
incomplete development of tracheoesophageal septum
"Leads to communication between the esophagus and the trachea"
132
What are the features of esophageal atresia?
many forms are present (as seen below). During breast
feeding the neonate develops chocking and vomiting due to passage of milk to the trachea.
133
What is the site of the kidney?
- The kidney lies on the posterior abdominal wall, retroperitoneal, one on each side of the vertebral column opposite the 12th thoracic and upper 3 lumbar vertebrae.
"Start of the abdomen"
134
What is the difference between the left kidney and the right kidney in terms of position?
- The left kidney is slightly higher than the right kidney by half an inch "just 1.5 cm" . It reaches up to the level of the 11th rib. While the right kidney reaches up to the 11th space due to presence of the liver on the right side. "Above it"
135
What is the shape of the kidney?
bean-shaped organ.
136
What is the size of the kidney?
10cm length, 5cm breath, 2.5 thickness.
"Divide by 2"
137
What are the poles, borders and surfaces of the kidney?
Two poles:
- The upper pole of the kidney is slightly thicker than the lower pole. "مفلطح فوق"
Two borders:
- The lateral border: convex.
- The medial border: concavo-convex. (Is convex at both ends, but is concave in the middle where it presents a vertical slit called the hilum of the kidney.)
Two surfaces:
- The anterior surface: Covered with peritoneum.
- The posterior surface: No peritoneal covering
138
How to identify the right kidney from the left kidney?
1. The medial border contains the hilum.
2. Anterior surface: convex and corresponds to the renal vein.
3. Posterior surface: flat and lies close to the pelvis of the ureter.
4. The ureter: is directed downwards towards the lower end.
139
What are the coverings of the kidney?
Arranged from within outwards: "2 fatty and 2 fibrous" "من جوة ل بره"
1. Fibrous capsule:
2. Perirenal (perinephric) fat "anterior and posterior"
3. Renal fascia "anterior and posterior"
4. Pararenal (paranephric) fat
140
What is the description of the fibrous capsule of the kidney?
- Is closely adherent to the kidney and can be easily stripped of the normal kidney substance
141
What is the description of perirenal fat?
Lies outside the fibrous capsule.
142
What is the description of the renal fascia?
- Condensation of areolar connective tissue that lies outside the Perirenal fat and encloses the kidney and the suprarenal gland.
143
What is the description of para renal fat?
- Lies external to the renal fascia, is part of the retroperitoneal fat.
144
What is the structure of the medulla of the kidney?
- Consists of a number of conical masses (renal pyramids) "inverted" each of which has an apex (towards the hilum) and a base (towards the cortex).
- The apices of the pyramids form the renal papillae which project into the minor calyces.
- Each minor calyx receives from l to 3 papillae.
"And each 2–3 mI or calyces form a major calyx which collect in the pelvis of the ureter"
145
What is the structure of the cortex of the kidney?
-Lies immediately beneath the fibrous capsule.
- Covers the bases of the pyramids.
- Extends deeply between the pyramids in the form of columns called renal columns.
146
What is the internal structure of the kidney?
- Each kidney has a dark brown outer cortex and a light brown inner medulla.
147
What are the posterior relations to the right and left kidney?
- Are the same in the right and left kidneys (4 muscles and 4 vessels and nerves)
148
What are the muscles related posteriorly to the kidney?
1. Diaphragm:
- Is related to upper end separating it from:
a. 11th and 12th ribs in left side and 11th intercostal space and 12th ribs (only) in the right side.
b. Costodiaphragmatic recess of the pleura.
2. Below the diaphragm:
- The kidney is related to the other 3 muscles:
a. Psoasmajor:medially.
b. Quadratus lumborum: the intermediate part (main part). c. Transversu sabdominis:laterally.
"Muscles a and b are related to the posterior abdominal wall while muscle c is related to the anterior wall"
149
What are the vessels and nerves between the kidney and quadratus lumborum?
a. Subcostal vessels (artery and vein).
b. Subcostal nerve (T12).
c. Iliohypogastricnerve(L1).
d. Ilioinguinal nerve (L1).
150
Do the anterior relations differ for each kidney?
Yes
151
What are the relations to the upper part of the right kidney anteriorly?
1. The right suprarenal gland: at the upper pole.
2. The second part of the duodenum: at the medial border and adjacent area of the anterior surface around the hilum.
3. The right lobe of the liver: is related to large area lateral to the second part of the duodenum (upper three-fourth of the anterior surface)
152
What are the relations to the lower part of the right kidney anteriorly?
1. The right colic flexure: below the hepatic area.
2. The loops of the jejunum (small intestine): are related to the lower medial area of the anterior surface
153
What are the relation to the upper part of the left kidney anteriorly?
1. The left suprarenal gland: from the upper pole to the hilum.
2. The spleen: close to the upper half of the lateral border of the kidney.
3. The stomach: is related to the triangular area at the upper third between the areas for the spleen and left suprarenal gland.
154
What are the relations to the middle part of the left kidney anteriorly?
1. The body of the pancreas.
2. The splenic artery: above the body of the pancreas.
155
What are the relations to the lower part of the left kidney anteriorly?
1. The descending colon: is related to the anterior surface close to the lower part of the lateral border. "The same"
2. The loops of the jejunum (small intestine): are related to the medial part of the lower part of the anterior surface. "The same"
156
What is the peritoneal covering of the right kidney?
Two areas are covered:
a- The hepatic area.
b- The area for jejunal loops. "Common"
Three areas are not covered:
a- Suprarenal area. "Common"
b- Duodenal area.
c- Right colic flexure area.
157
What is the peritoneal covering of the left kidney Danielle?
Three areas are covered:
a- splenic area
b- Gastric area
c- Jejunal area
Three areas are not covered:
a- suprarenal area
b- Pancreatic area
c- Descending colon
158
What is the hilum of the kidney?
- It is a vertical opening at the middle of the medial border.
159
What does the hilum of the kidney lead to?
- It leads to sinus of the kidney.
160
What does the hilum of the kidney transmit? "VAP"
1. Renal vein (anterior).
2. Renal artery (middle).
3. Pelvis of ureter (posterior and downward).
4. Lymphatics.
5. Fat.
161
What are the Renal vessels?
A. Renal arteries: Arise from the aorta at right angle, at the level of the upper border of L2.
B. Renal veins: terminate in I.V.C. "Left is longer'
162
What are the lymphatic vessels of the kidney?
- Are drained into the lateral (para) aortic lymph nodes around the origin of the renal artery.
163
What are the nerves of the kidney?
1. Sympathetic fibers: are derived from the 10th ,11th and12 the thoracic segments of the spinal cord. "To sympathetic plexus around renal artery"
2. Parasympathetic fibers: are from the vagus nerves.
164
Where is renal pain located?
- Renal pain radiates from back and lumbar region to the anterior abdominal wall and down to external genital organs.
165
What are the factors supporting kidney in its position?
1. Perinephric fascia: false capsule from the surrounding tissues.
2.Perinephric fat: between perinephric fascia and true capsule of kidneys.
3. Renal vessels.
4. Suspensory ligament from the diaphragm.
5. Apposition of the neighboring viscera and the intra-abdominal pressure.
166
What is the surface anatomy of the kidney?
- The kidney lies within Morris's rectangle, which is drawn by two horizontal and two vertical lines:
- The upper horizontal line: opposite the spine of T11.
- The lower horizontal line: opposite the spine of L3.
- The two vertical lines: are drawn 2.5 cm "medial" and 7.5 cm "lateral" from the median plane.
167
What is the surface anatomy of the upper pole of the kidney?
T12, (2.5 cm from median plane).
168
What is the surface anatomy of the hilum of the kidney?
L1 (transpyloric plane), 5 cm from median plane.
169
What is the surface anatomy of the lower pole of the kidney?
L3, (7.5 cm from median plane).
170
What is the definition of suprarenal glands?
endocrine gland, consists of an outer cortex and an inner medulla.
171
What is the site of suprarenal glands?
- It is closely related to the upper poles of the kidney and the adjoining part of the medial border.
- The left gland reaches nearer to the hilum of the kidney than the right.
172
What is the covering of Suprarenal glands?
- Is surrounded by perirenal fat within the renal fascia, but is separated from the kidney by a layer (septum) of fibro-areolar tissue.
173
What is the size of suprarenal glands?
- The gland at birth is third the size of the kidney, while in the adult it is only one-thirty.
174
What is arterial supply of Suprarenal glands?
1. Superior suprarenal: from inferior phrenic artery.
2. Middle suprarenal: from aorta.
3. Inferior suprarenal: from renal artery.
175
What is a Venous drainage of the suprarenal glands?
1. Right suprarenal: drains into the I.V.C.
2. Left suprarenal: drains into the left renal vein.
176
Compare between the right and left suprarenal glands according to:
Shape
Size
Hilum
Vein
Shape: triangular in outline - semilunar in shape
Site: doesn’t reach the hilum - reaches the hilum
Hilum: directed upwards - directed downwards
Veins: very short and drains into the I.V.C - long and drains into the left renal vein
177
What is the origin of the urogenital system?
➢ The urogenital system develops from a common mesodermal ridge (The intermediate mesoderm)
➢ The intermediate mesoderm forms a longitudinal ridge named urogenital ridge. "Gives urinary and genital organs"
178
What is the site of the urogenital Ridge?
The urogenital ridge:
▪ Extends from the cervical to the sacral region and appears in the posterior wall of the abdominal cavity on each side of the dorsal mesentery. "Two ridges"
179
What happens to the urogenital Ridge?
Forms 3 elevations (from medial to lateral):
1. Genital ridge: Gives rise to primary sex organs (ovary or testis).
2. Nephrogenic cord: Gives rise to the urinary organs. "Our study in this lec"
3. Paramesonephric duct: Gives rise to female sexual ducts.
180
What are the steps of the development of the kidney?
➢ The development of the kidney passes through 3 stages:
▪ Pronephros. "Just for 1 week"
▪ Mesonephros.
▪ Metanephros.
181
What is the time of development of pronephros, mesonephros and metanephros respectively?
4th week "with heat and lungs"
Middle of 4th week "before complete degeneration of pronephric tubules"
5th week
182
What is the site of pronephros, mesonephros and metanephros respectively?
Cervical region
Thoracic and Upper lumber region
Sacral region
183
What is the function of pronephros, mesonephros and metanephros respectively?
- Temporary & non-functional
- Acts as a temporary excreting unit between 6th and 10th week
- It becomes Functional near the 10th week when urine passes in the amniotic cavity and mixes with the amniotic fluid, this fluid is swallowed by the fetus and recycled by the kidneys
184
What are the steps of development in pronephros stage?
➢ The nephrogenic cord in the cervical region divides into 5-7 nephrotomes which are arranged into pronephric vesicles.
➢ The pronephric vesicles "after degeneration of centre" elongate to form pronephric tubules.
➢ Each tubule has 2 ends:
▪ Medial end: opens into the intraembryonic coelom.
▪ Lateral end: grow caudally and unite to form the pronephric duct which opens into the cloaca. "Last part in hindgut"
➢ Small branches of dorsal aorta invaginate the walls of pronephric tubule and coelomic cavity forming internal &external glomeruli respectively.
185
What is the fate of pronephros stage?
➢ Pronephric tubules: degenerate completely.
➢ Pronephric duct: receives mesonephric tubules & becomes mesonephric duct.
186
What are the steps of development in the Mesonephros stage?
➢ The nephrogenic cord in the thoracic & upper lumbar region divides into nephrotomes which are arranged into mesonephric vesicles.
➢ The mesonephric vesicles elongate to form mesonephric tubules (70 – 80).
➢ Each tubule grows rapidly to form S shaped "due to elongation" loop which has 2 ends:
▪ Medial end: not connected to the coelomic cavity & has only an internal glomerulus. "Invagination of celom only"
▪ Lateral end: opens into the Mesonephric (Wollfian) duct which is the remaining part of the pronephric duct that extends caudally to open into the cloaca.
187
What is the fate of mesonephros stage?
- Divided into fate of mesonephric tubules and mesonephric duct
188
What is the fate of mesonephric tubules?
- Fate of mesonephric tubules:
in males:
1. vasa efferentia & head of epididymis
2. paradidymis.
In females:
disappear, except remnants epoophoron & paroophron close to ovary.
189
What is the fate of mesonephric duct?
In males: forms genital ducts:
- cranial to caudal
1. appendix epididymis,
2. epididymis (body & tail),
3. vas deferens
4. seminal vesicle.
5. ejaculatory duct
6. trigone of urinary bladder
7. ureteric buds
In females: disappears, except:
1. its caudal end (Gartner's duct) close to vagina.
2. trigone of urinary bladder
3. ureteric buds
190
What are the sources of development of metanephros stage?
Develops from 2 sources:
1) Ureteric bud: gives the collecting system.
2) Metanephric cap: gives the excretory units.
191
Where do ureteric buds arise from?
- It arises as a diverticulum from the distal portion of mesonephric duct near cloaca.
192
What are the steps of development of ureteric buds?
➢ It grows dorsally & cranially penetrating the metanephric cap.
➢ The stalk of ureteric bud becomes the ureter.
➢ The cranial end expands to form the renal pelvis.
➢The cranial end undergoes repeated branching forming successive generations of tubules:
▪ The first 4 generations enlarge & coalesce to form major calyces.
▪ The second 4 generations coalesce to form the minor calyces.
▪ The remaining generations form the collecting tubules
193
What are the steps of development of metanephrons cap?
➢ Each collecting tubules is covered at its distal end by metanephric cap (derived from the nephrogenic cord in the sacral region).
➢ The metanephric caps form the renal vesicles, which elongate to form metanephric tubules.
➢ Capillaries grow into the proximal end of each tubule & differentiated into renal glomeruli.
➢ These tubules together with their glomeruli form nephrons:
▪ The proximal end of each nephron forms Bowman’s capsule while the distal end opens into a collecting tubule.
▪ Continuous lengthening of the nephron results in formation of the proximal convoluted tubules, loop of Henle & distal convoluted tubules.
194
What are the developmental changes that occur to metanephric kidney?
"SAMB"
Changes in Shape
Ascent of the kidney
Medial rotation of the kidney
Change in the Blood supply
195
What are the changes in the shape of metanephric kidney?
➢ At first, the fetal kidney is lobulated.
➢ This lobulation disappears before birth & its surface becomes smo
196
What are the changes in the level of the kidney?
➢ At first, the kidney develops inside the pelvis.
➢ Later, it shifts upward in the abdomen and reaches just below the suprarenal gland.
197
What are the changes in the rotation of the kidney?
➢ At first, the hilum of the kidney faces anteriorly.
➢ As the kidney ascends it rotates medially 90°.
198
What are the changes in the blood supply of the kidney?
➢ As the kidney ascends it changes its blood supply:
➢ It takes the blood supply from the nearest main artery:
▪ Median sacral artery.
▪ Internal iliac artery.
▪ Common iliac artery.
▪ Abdominal aorta.
199
What are of the anomalies of development of the kidney?
"Sir Vast Vonlf"
1- Number.
2- Volume & Structure.
3- Site.
4- Form & fusion.
5- Rotation.
6- Lobulation.
7- Renal vasculature.
200
What are anomalies in number of kidney?
"May be more than 2 kidneys!"
✓ Unilateral renal agenesis (hypertrophy)
✓ Bilateral renal agenesis (incompatible with life)
✓ Supernumerary Kidney (caudal to the dominant kidney)
201
What is the cause of unilateral renal agenesis?
- Failure of ureteric bud or nephrogenic ridge to develop on one side. "Its origin"
202
What is the cause of bilateral renal agenesis?
- Failure of ureteric bud or nephrogenic ridge to develop on both sides.
203
What is the cause of supernumerary kidney?
- A second ureteral outpushing off the mesonephric duct or Branching from the initial ureteric bud.
204
What are the anomalies of volume of the kidney?
✓ Hypoplasia
205
What are the characteristics of hypoplasia of kidney?
- small kidney in one or both sides (reduced renal mass).
206
What is the cause of hypoplasia of the kidney?
- incomplete development and differentiation of ureteric bud.
207
What is the cause of polycystic kidney?
- Failure of ureteric bud derivatives to join metanephric tubules.
208
What are the anomalies of the structure of the kidney? And what are its features?
- Polycystic kidney "very dangerous"
Features:
▪ There is diffuse, bilateral, progressive cystic deformity of both kidneys which cause severe renal insufficiency.
▪ The normal nephron is compressed by expanding cysts.
209
What are the anomalies of site of the kidney? And what are its features?
✓ Simple renal ectopia
Features:
An ectopic kidney can be found in:
▪ Pelvic kidney: Opposite the sacrum and below the aortic bifurcation.
▪ Lumbar kidney: opposite sacral promontory in the iliac fossa.
▪ Abdominal kidney: above the iliac crest and adjacent to the 2nd lumbar vertebra.
210
What is the cause of simple renal ectopia?
- Defective development of the metanephric cap that by itself fails to induce ascent.
211
What are the anomalies of form and fusion of the kidney?
Horseshoe Kidney
212
What are the features of horseshoe kidney?
"Associated with ectopia and abnormality in rotation but however it is asymptomatic"
▪ Two renal masses lie vertically on either side of the midline and are connected at their lower poles "nearer" (may be upper poles) by a parenchymatous "renal" or fibrous tissue isthmus.
▪ Ureters of the horseshoe kidney are usually anteriorly placed. "No rotation as they are are attached"
▪ Kidneys are lying in the lower lumbar region as the inferior mesenteric artery obstructs the isthmus and prevents further ascent.
▪ Asymptomatic as its collecting system develops normally.
213
What are the causes of horseshoe kidney?
- developing metanephric masses lie close to one another. Any disturbance in this relationship may result in their union at one pole.
214
What are the anomalies in rotation of the kidney?
✓ Non-rotation: The hilum is directed forwards.
✓ Reversed rotation: The hilum is directed laterally. "Vessels appear anteriorly"
215
What are the anomalies of lobulation of the kidney? And what are its features?
✓ Lobulated kidney
Features: persistence of fetal lobulation.
216
What are the Anomalies of renal vasculature of the kidney and what are its features?
"حسب مصدر ونهاية artery"
✓ Multiple renal arteries
Features: the kidney is supplied by more than one artery.
✓ Accessory renal artery:
Features: most commonly arise from abdominal aorta and supply the lower pole of the kidney. "Not the hilum"
✓ Aberrant vessels:
Features: the kidney is supplied by arteries not arising from aorta or main renal artery.
217
What are the anomalies of the development of the ureters? "NsTT"
1- Number.
2- Termination.
3- Structure.
218
What are the anomalies of the number of the ureter and what are its features?
✓ Ureteral agenesis "Due to failure of development of the ureteric bud and it is accompanied by renal agenesis"
✓ Duplication of the ureter:
Features:
▪ Double pelvis of the ureter: Due to premature division of the ureteric bud near the termination.
▪ Bifid ureter (Partial duplication): Double ureters and double pelvis with a common orifice in the urinary bladder.
▪ Double ureters (complete duplication): The two ureters open independently into the bladder.
219
What are the anomalies of termination of the ureter and what are its features?
Ectopic ureteric orifice
Features:
▪ In male: the additional ureter may open into the "pu" prostatic urethra, "sv" seminal vesicle or the "ed" ejaculatory duct.
▪ In female: it may open into the urethra, vagina or vestibule. "Vv"
220
What are the anomalies of structure of the ureter and what are its features?
Features:
✓ Atresia & hypoplasia.
✓ Mega-ureter; caused by obstruction to urine flow.
✓ Ureteral stenosis & stricture.
✓ Folds of the ureters.
✓ Ureteral Valves.
✓ Ureteral diverticula.
221
what is the cause of urethral agenesis and duplication of the ureter respectively?
- Complete failure of the development of the ureteric bud.
- Premature division of the ureteric bud.
222
What are the causes of anomalies of renal vasculature of the kidney?
- Failure of complete degeneration of the primitive vascular channels.
223
What are the causes of ectopic ureteric orifice of the ureter?
- Second ureteric bud arising from a single mesonephric duct near its termination.
224
What is the cause of anomalies of structure of the ureter?
- failure of ureteral bud development and canalization.
225
What are the most common anomalies of the kidney and ureter?
unilateral renal agenesis, polycystic kidney, ectopic kidney & ureteral strictures.
226
What is the definition of cloaca? And what is it lined by?
It is expanded caudal part of hindgut, caudal to allantois, It is lined with endoderm.
227
What are the steps of development of the cloaca and what are its derivatives?
1) mesoderm in angle [] allantois & hindgut proliferates to form urorectal septum (4th week).
2) then the septum grows caudally to fuse with cloacal membrane, thus:
A. cloaca is divided into:
1. Anorectal canal: posterior part.
2. Primitive urogenital sinus: anterior part.
B. cloacal membrane (at 7th° week) is divided into:
1. Anal membrane: posterior part.
2.Urogenital membrane: anteior part.
3) primitive urogenital sinus: is subdivided by entrance of 2 mesonephric ducts into:
A. Vesico-urethral canal: cranial part. Its apex is connected to allantois. It forms:
a. Urinary bladder except trigone.
b.Upper anterior wall of prostatic urethra in males or anterior wall of female urethra
B. Definitive urogenital sinus: caudal part. It is divided into 2 parts:
a.Pelvic part: upper part. It forms lower part of prostatic urethra & membranous urethra in males or lower part of vagina in females.
b. Phallic part: in males, gives lower part. It forms the lining of penile (spongy) urethra except that in glans penis & vestibule of vagina in female
228
What is the urinary bladder development?
1) Lining of urinary bladder
a. Vesico-urethral canal (endoderm): forms whole lining of urinary bladder except that of trigone & apex of bladder.
b. Allantois (endoderm): its proximal part forms apex of urinary bladder while its distal part (called urachus) is obliterated after birth & forms median umbilical ligament, which extends from apex of bladder to umbilicus
C. Caudal parts of mesonephric ducts (mesodermal): open into vesico-urethral canal and becomes absorbed to form trigone of urinary bladder
2) Smooth muscle & connective tissue of bladder: are derived from splanchnic mesoderm..
229
What is the cause of ectopic vesica?
lack of migration of mesoderm into region [ ] umbilicus & cloacal membrane. With rupture of thin ectoderm there
230
What are the features of ectopic vesica?
1) Absent infra-umbilical part of abdominal wall,
2) absent anterior wall of bladder
3) Exposure of trigone of bladder, ureteric orifices
4) Defective dorsal aspect of penis, Epispadius.
5) Scrotum is separated into 2 halves
6) Wide-spaced pubic bones
7) High Alfa fetoprotein in amniotic fluid
231
What are the anomalies of urachus?
a. Urachal fistula: due to failure of obliteration of urachus (or allantois).
It extends from bladder to umbilicus. Urine may dribble from umbilicus.
b. Urachal sinus: due to patency of distal (upper) part of urachus
C. Urachal cyst: due to patent isolated middle part of urachus. (not continuous with the bladder)
d. Urachal diverticulum: due to persistence of proximal part of urachus (continuous with the bladder)
232
What forms the urethra in females?
urethra develops from:
1) Anterior wall of female urethra: from caudal part of vesico-urethral canal.
2) Posterior wall of female urethra: from mesonephrcic duct
233
What forms the urethra in Male?
urethra consists of 3 parts:
1) Prostatic urethra:
a. Its upper part of prostatic and also the preprostatic part:
i. Anterior wall develops from caudal part of vesico-urethral canal.
il. Posterior wall above openings of ejaculatory duct, develops from mesonephric ducts
b. Its lower part: develops from pelvic part of definitive urogenital sinus.
2) Membranous urethra: develops from pelvic part of definitive urogenital sinus.
3) Spongy (penile) urethra:
234
How is the spongy urethra developed?
develops from:
a. Endoderm of Phallic part of definitive Urogenital sinus.
b. Ectoderm of glans penis which forms the part of urethra in glans penis.
Development of spongy urethra:
i. endoderm of phallic part of urogenital sinus forms (urethral plate) which extends on under aspect of the penis.
ii. urethral plate is grooved longitudinally forming urethral groove.
iii. edges of urethral groove (urethral folds =ectoderm) fuse on under surface of penis
iv. Urethral groove lining becomes urethral canal which ends blindly at glans penis.
v. A cord of ectodermal cells (glandular plate) grows from tip of glans penis within glans.
VI. It becomes canalized & communicates with urethral canal.
235
What are the anomalies of urethra?
- hypospadius:
- epispadius:
236
What is hypospadias?
most common anomaly in penis, urethra opens on undersurface of penis
237
What are the types of hypospadias?
A. Glandular: urethral orifice is on ventral surface of glans penis
B. Penile: urethral orifice is on ventral surface of body of penis.
C. Penoscrotal: urethral orifice is at junction Of penis and scrotum
238
What are the features of epispadias?
urethra opens on dorsum of penis. Associated with ectopia vesica..
239
What is the cause of epispadias?
It is due to development of the genital tubercle in the region of the urorectal septum
instead of developing in the cranial margin of the cloacal membrane. Hence, a portion of the
cloacal membrane is found cranial to the genital tubercle. When this membrane ruptures, the
outlet comes to lie on the dorsal aspect of the penis
240
What is the cause of hypospadias?
Failure of fusion of urogenital folds. Or Failure of canalization of glans penis.
