Embryology Flashcards
The pharyngeal arches, pharyngeal pouches, pharyngeal cleft, and pharyngeal membrane all make up the ?
Pharyngeal apparatus
The pharyngeal apparatus contributes to the formation of what and what regions of the body?
The Head and Neck regions
The development of the pharyngeal apparatus begins in what week of Intra-Uterine Development
4th week
The pharyngeal apparatus develops from the?
Primitive pharynx caudal
Folds/elevations on the lateral wall of the primitive pharynx caudal is called
The pharyngeal apparatus
The inner spaces between the pharyngeal arches are called?
Pharyngeal pouches
The grooves on the outer pharyngeal wall are called?
Pharyngeal cleft
The first artery of the pharyngeal arch becomes the?
Maxillary artery
The second artery of the pharyngeal arch becomes?
Hyoid and stapedial arteries
The third artery of the pharyngeal arch becomes?
- Common carotid artery
- Internal carotid artery
The fourth artery of the pharyngeal arch becomes?
- Aortic arch
- Subclavian artery
The sixth artery of the pharyngeal arch becomes?
- Ductus arteriosus
- Pulmonary artery
The first arch cartilage of the pharyngeal arch is called?
Meckel’s cartilage
The second cartilage of the pharyngeal arch is called?
Richerts cartilages
The Merkel’s cartilage forms?
The malleus and incus of the middle ear
Reichert’s cartilage forms?
The stapes bone in middle ear, and body of hyoid bone
The 4th and 6th cartilages form ?
The thyroid, cuneiform, corniculate, arytenoid, and cricoid cartilages
The 1st Arch nerve is also called?
Trigeminal nerve
What embryonic nerve supplies the taste fibres and the anterior ⅔ of the tongue
The chorda tympani
The 2nd arch nerve is also called
Facial nerve
The facial nerve supplies?
All muscles derived from the second arch
The 3rd arch nerve is also called?
Glossopharyngeal nerve
The 4th arch nerve is also called?
The superior laryngeal nerve
The 6th arch nerve is also called?
The recurrent laryngeal nerve
The 1st arch muscle forms the ?
Muscle of mastication
The 2nd arch muscle forms the?
Muscle of facial expression, and posterior belly of digastric
The only muscle derived from 3rd arch is the?
Stylopharyngeus
The cricothyroid, levator veli palati, constrictors of the pharynx are muscles derived from the?
4th arch cartilage
The intrinsic muscles of the larynx is derived from the?
Sixth arch
The distal part of the tubotympanic recess becomes ?
The middle ear cavity and mastoid Air cells
The first pharyngeal pouch elongates to form a diverticulum known as?
Tubotympanic recess
The proximal tubular part of the pharyngeal pouch forms the?
Eustachian / auditory tube connecting the nasopharynx and middle ear
The 2nd pharyngeal pouch form tiny solid buds that develop into?
palatine tonsils
The ventral tubular part forms ?
the thymus
The 4th pharyngeal pouch forms?
Parathyroid gland
The external auditory meatus(ear canal) is formed from
The 1st pharyngeal cleft
Clinical correlations of the pharyngeal cleft
- Brachial cyst & Fistula
- First arch syndromes
Examples of the defects to the 1st arch include;
Trecher Collins syndrome
Pierre-robin syndrome
Digeorge
______ is unique to each person, and is the basis for identity?
Face
Abnormalities to congenital development are caused by
Teratogen
The face forms from?
Oropharyngeal membrane
The face developed from what embryonic tissues?
All 3 embryonic tissues (Ectoderm, mesoderm and endoderm)
The fronto-nasal process rises from?
Neural crest
A plate-like thickening of the epithelial layer of an embryo which develops into a sense organ is called
A placode
At week 10, inter-maxillary process forms?
The nasal bridge and the philtrum of upper lip
The tissues of the 1st pharyngeal arch originates from?
Mesoderm and neural crest
Nasal placodes appear at week 4 and are the precursor to the olfactory epithelium.
True or False
True
The fusion of _____ and _____ results in formation of philtrum of upper lip?
- Maxillary processes
- Medial nasal process
Mention 2 events that take place in week 5 of facial development
- The oropharyngeal membrane disintegrates leaving behind a communication between the digestive tract and external environments
- The eyes which are initially located at the side of the head, face forward as the head grows
At what week will the embryo have human appearance?
7th week
The upper part of the mouth that separate the nasal and oral cavity is called?
Palate
The opening towards the back of the nasal cavity that connects the oral and nasal cavities is called
Choana
Embryologically, the primary palate gives rise to?
Anterior ⅓ from the incisive cleaned and upper 4 incisors
Embryologically, the secondary palate gives rise to?
Hard palate and soft palate
Development of the palate takes place in what week?
7th - 8th week
2 significant mechanisms that can cause a cleft palate include?
- Growth retardation
- Mechanical obstruction
_________ and _________ are congenital clinical implications related to development of palate and nasal septum.
- Cleft lip/palate
- Choanal atresia
Loosely organized cells derived from mesodermal embryonic tissues, that later develop into connective tissue and skeletal tissues. Are called?
Mesenchyme
Mention 4 things the inter-maxillary segment, gives rise to?
- Bridge of nose
- Philtrum
- 4 upper incisors
- Primary palate
The structures of the oral cavity derive from?
First branchial arch
Which pharyngeal arch (es) contribute to the development of different parts of the tongue
1st, 2nd, 3rd, and 4th pharyngeal arches
Development of the tongue begins with growth of medial swelling From 1st pharyngeal arch known as?
Tuberculum Impar
The tuberculum impar, together with 2 lateral lingual swelling which fuse and overlap the tuberculum impar, form?
The anterior ⅔ of the tongue
The anterior ⅔ of the tongue is innervated by?
Chorda tympani
The hypobranchial eminence forms what part of the tongue?
The posterior ⅔ of the tongue
The posterior ⅔ of the tongue is innervated by?
Glossopharyngeal nerve
The most posterior part of the tongue is formed from the 4th pharyngeal arch, and This part is innervated by?
Superior laryngeal nerve
The muscle of the tongue derive from the myoblast which originate in?
Occipital somites
The muscles of the tongue are innervated by?
Hypoglossal nerve
The muscles of the tongue are classified in 2, name them?
- Extrinsic muscles
- Intrinsic muscles
Examples of extrinsic muscles of the tongue, include?
- Genioglossus
- Palaglossus
- Hyoglossus
- Styloglossus
Mnemonic: Great P.H.S
What is the action of Extrinsic muscles of the tongue?
They allow the tongue move in all directions
Extrinsic muscles of the tongue have their origin where?
Structures adjacent to the tongue
Examples of intrinsic muscles of the tongue?
- Verticalis
- Superior longitudinal
- Inferior longitudinal
- Transverses muscles
Mnemonic: V.SIT
Intrinsic muscles all have their origin and insertion where?
Inside the tongue
The intrinsic muscles of the tongue are responsible for what action?
Changing the shape
of the tongue
Development of taste buds on the lingual epithelium begins at?
Week 8 of IUL
Primordial taste buds differentiate into different cell types at?
11th - 13th week
Mention the functions of the tongue
- Taste function
- Speech
- Food manipulation (aids digestion)
The respiratory system, including the lining epithelium of the larynx,trachea, bronchi and lungs originates from?
Endodermal layer
The respiratory diverticulum develops from
A ventral outgrowth of the cranial part of the foregut
The respiratory diverticulum begins as a midline groove, but it later deepens form?
Laryngo-tracheal diverticulum
The proximal part of the laryngo-tracheal diverticulum forms?
Larynx and Trachea
The distal part of the laryngo-tracheal diverticulum bifurcates into
2 Bronchial /Lung buds
The trachea develops from?
Laryngo-tracheal diverticulum
Epithelium and gland of trachea develop from?
Endoderm
Cartilage, muscle and connective tissues of the respiratory system are derived from?
Splanchnic mesoderm
around laryngo-tracheal groove
Each lungs consist of _____ bronchopulmonary segments
10
Mention 2 congenital defects related to bronchi and lungs
- Tracheoesophageal fistula
- Tracheal sternosis
The stages of lung maturation are?
- Pseudoglandular stage
- Canalicular stage
- Terminal sac
- Alveolar stage
The pseudoglandular stage ranges from?
Week 5 to 16
The canalicular stage ranges from?
Week 16 to 26
The terminal sac (saccular) stage ranges from?
Week 26 to birth
The alveolar stage ranges from?
8 months to 8 years
Examples of developmental changes that take place in the pseudoglandular stage include;
- Formation of Bronchial tree
- Differentiation of airway epithelium
- Development of Smooth muscle
Production of surfactant begins at what week?
24th week
A child, born at the end of the canalicular stage could survive.
True or False
True
Importance of surfactant include;
- Prevents lungs from collapse by reducing surface tension
- Improves lungs compliance
- Prevents atelectasis
Fetal Breathing Movement starts before birth.
True or False
True
Mention factors that affect lung development?
- Adequate thoracic space
- Fetal Breathing movements
- Adequate volume of amniotic fluid
- Vascular development and blood supply
For medicolegal purposes, the lungs of a still born and live born baby can be differentiated by?
Placing in the lungs in water, the still born lungs would sink, and
The live born lungs would float due to presence of air inside the lungs
______ is caused by surfactant deficiency
Respiratory Distress Syndrome
Respiratory Distress Syndrome is treated by use of?
Corticosteroids and thyroxine
Failure of the cranial neuropore to close leads to?
Anencephaly
Failure of the caudal neuropore to close leads to?
Spina bifida
Both the urinary and genital systems develop from?
Intermediate mesoderm
In IUD of the kidney, there are 3 systems, namely?
- Pronephros
- Mesonephros
- Metanephros
_____ is the rudimentary and non-functional kidney system in IUD?
Pronephros
______ forms the permanent kidney?
Metanephros
In males, ______ ducts persist and participate in the formation of the genital system .
Mesonephric
The collecting ducts of the permanent kidney develop from?
Ureteric buds
Ureteric buds give rise to; _______, _______, _______ and ________
- Ureter
- Renal pelvis
- Major and minor calyces
- 1 to 3 million collecting tubules
The excretory units of the kidney develop from?
Metanephric mesoderm
Continuous lengthening of the excretory tubule results in formation of?
- Proximal convoluted tubule
- Loop of henle
- Distal convoluted tubule
At birth, there are approximately ______ nephrons in each kidney?
1 million
Following the differentiation of glomerular capillaries, urine production begins at what week?
10th week
Every newly formed collecting tubule is covered at its distal end by a?
Metanephric tissue cap
The ascent of the kidney is caused by?
Diminution of body curvature and growth of body in lumbar and sacral regions
Clinical abnormalities in location of kidney include;
- Pelvic kidney
- Horse shoe kidney
- Accessory renal arteries
The definitive kidney is formed from the metanephros at?
Week 12
Urine in IUL is removed via
It passes into amniotic cavity and mixes with amniotic fluid
In fetal life, the kidneys are not responsible for excretion of waste products. Rather the ________ serves this function?
Placenta
Within the 4th-7th week of IUD, the cloaca divides into?
- Urogenital sinus
- Anal canal
A septum between the urogenital sinus and anal canal is called?
Urorectal septum
The tip of the urorectal septum will form?
Perineal body
_____ is a fetal structure that is later obliterated
Allantois
The urogenital sinus has 3 parts, namely?
- Urinary bladder
- Pelvic part
- Phallic part
In males, the definitive urogenital sinus develops into?
Penile urethra
In males, the ejaculatory ducts are formed from?
The mesonephric ducts
_________ is formed by buds from the urethra
Prostate gland
_________ is formed by budding from the ductus deferens
Seminal vesicles
The epithelium of the urethra in both males and females originate from?
The endoderm
In females, the cranial part of the urethra gives rise to?
Urethral and Para-urethral glands
_______ is the part of the mesoderm of an embryo that develops into a connective tissue, bone or cartilage
Mesenchyme
Example of bladder defects are;
- Urachal fistula
- Urachal cyst
- Urachal sinus
- Exstrophy of the bladder
- Exstrophy of the cloaca
The nervous system is derived from what embryonic layer?
Ectoderm
______, ______ and ______ make up the Brainstem (hind brain)?
Pons, Cerebellum and Medulla oblongata
The development of the nervous system behind at what week?
3rd week.
It begins with neurulation
The brain and the spinal cord is covered by 3 meninges, namely?
Pia, Arachnoid, and Dura matter
______ stimulates growth factors and neuroectodermal induction?
The Notochord
Cellular condensation of the neutral plate leads to formation of ______, _______ and then ______
Neural groove,
Neural fold,
then the Neural tube
Cells that migrate to the top before formation of the neutral tube are called?
Neural crest cells
Neural crest cells form what part of the nervous system?
Peripheral nervous system
Cells within the neural tube form what part of the nervous system?
Central nervous system
Closure of the rostral neuropore takes place by?
Day 25
Closure of the caudal neuropore, takes place by?
Day 26-28
(About 2 days after closure of cranial neuropore)
The primary vesicles appear at?
They include?
4th week
They are; Prosencephalon, Mesencephalon, Rhombencephalon
The opening around the junction of the medulla and spinal cord at the level of vertebrae C1, is called?
Foramen magnum
______ are the passage ways for CSF in the brain?
Ventricles
Ependymal cells are found within the _______ of the brain?
Ventricles
The foramen between the 2 lateral ventricles, is called?
Foramen of Monroe
The failure of the rostral neuropore to close by day 25 results in?
Anencephaly
The failure of the caudal neuropore to close by the 28th day would result in?
Spina bifida
At the 5th week, the prosencephalon divided to form _______ and ______?
- Telencephalon
- Diencephalon
At the 5th week, the Rhombencephalon divides to form _______ and ______?
- Metencephalon
- Myelencephalon
The Mesencephalon doesn’t divide, it just develops to form?
The Midbrain
The Telencephalon forms?
The Cerebrum (cerebral cortex and cerebral hemispheres)
The Diencephalon forms?
- Thalamus
- Hypothalamus
- Sub thalamic
The Diencephalon forms?
- Thalamus
- Hypothalamus
- Sub thalamic
_______ is caused by inflammation of the Dura matter?
Head aches