Anatomy [Week 1] Flashcards
What is in the SUBMANDIBULAR triangle? (4)
- Submandibular gland
- Hypoglossal n. (CN XII)
- mylohyoid m.
- facial artery/vein/branches of FACIAL NERVE
What is in the SUBMENTAL triangle? (2)
- Anterior jugular vein origin
- mylohyoid muscles
What is in the CAROTID triangle? (10)
- carotid sheath [with Common Carotid a. and branches, Internal Jugular v. and tributaries, and vagus nerve (CN X)
- External carotid a.
- Superior Thyroid a.
- Ascending pharyngeal a.
- Lingual a.
- Facial a.
- Hypoglossal n. (CN XII)
- Superior root of ansa cervicalis
- Accessory nerve (CN XI)
- Thyroid gland/cartilage
What are in the MUSCULAR triangle? (7)
- Sternothyroid m.
- Sternohyoid m.
- Thyroid gland
- Ansa Cervicalis
- Cricoid cartilage
- Cricothyroid membrane
- Tracheal ring
What is in the ROOT OF THE NECK? (9)
- Phrenic n.
- Vagus n.
- Recurrent laryngeal n.
- Common carotid a.
- Inferior thyroid a.
- Subclavian a/v
- Transverse cervical a.
- Vertebral a.
What is in the OCCIPITAL triangle? (8)
- External jugular v.
- Posterior branches of cervical plexus (4): Greater auricular n., lesser occipital n., supraclavicular n., transverse cervical n
- Accessory n.
- Trunks of brachial plexus
- Transverse cervical a.
What would be injured if there was a tumor on a patient’s thyroid? How would the patient present?
The recurrent laryngeal n. would be injured and there would be paralysis of laryngeal muscles, causing voice hoarseness
What are the EXTERNAL CAROTID ARTERY branches?
SOME: Superior thyroid ANGRY: Ascending pharyngeal LADY: Lingual FIGURED: Facial OUT: Occipital P: Posterior auricular M: Maxillary S: Superficial temporal
What are the branches of the FACIAL NERVE (motor)?
Posterior auricular TWO: Temporal ZEBRAS: Zygomatic BIT: Buccal MY: Marginal mandibular COCCYX: Cervical
What are the CAROTID SHEATH contents?
I “SEE”: Internal carotid
10: Vagus n. (X)
CC: Common Carotid a.
in the IV: Internal jugular Vein
Which nerves supply the scalp?
G: Greater occipital/Greater auricular L: Lesser occipital A: Auriculotemporal S: Supratrochlear S: Supraorbital
Which arteries supply the scalp?
O: Occipital {ECA}
PA: Posterior Auricular {ECA}
S: Superficial Temporal {ECA}
S: Supraorbital {ICA}
S: Supratrochlear {ICA}What are the layers of the scalp?
S: Skin C: Connective tissue A: Apopneurosis L: Loose areolar tissue P: Pericranium
What happens when an infection spreads in the veins of the “DANGER TRIANGLE” of the face?
May spread to cavernous sinus via facial vein anastomoses with the superior ophthalmic vein; especially since the facial vein contains no valves
Which anastomoses are involved in the connection of the internal and external carotid arteries in the face?
Anastomoses between the facial a. and superficial temporal a. with the palpebral and dorsal nasal branches of the ophthalmic a.; all drain into the cavernous sinus (directly/indirectly)
Which nerve can be damaged with a parotidectomy? How does the patient present?
- Facial nerve
- bilateral asymmetry regarding muscles of facial expression because CN VII lesioned; tone is lost
What happens if there is an infection in the “DANGEROUS AREA OF THE SCALP”?
All the emissary veins are there and so infections spread to intracranial sinuses or to the brain via these veins
neurocranium
surrounds brain
calvaria
skullcap
viscerocranium
skeleton of face
nasion
craniometric point: junction of nasal bones and frontal bone
glabella
craniometric point: smooth portion of frontal bone
pterion
craniometric point: junction of frontal, parietal, temporal and sphenoid bones (forms an H)
bregma
craniometric point: junction of coronal and sagittal sutures
vertex
craniometric point: the most superior portion of neurocranium
lambda
craniometric point: junction of sagittal and lambdoid sutures
asterion
craniometric point: junction of parietal, occipital and temporal bones
inion
the most prominent posterior protrusion of the occipital bone
How many layers of the PERICARDIUM are there and what are they called?
2; epicranium and endocranium
What are the branches of the TRIGEMINAL NERVE (CN V)? Where does it emerge?
CNV1=Opthalmic
CNV2=Maxillary
CNV3=Mandibular
-from brainstem at mid-pons level
Where are the cell bodies of the TRIGEMINAL NERVE and what kind of neural information is sent?
- TRIGEMINAL GANGLION
- sensory neurons
What are the branches of the EXTERNAL CAROTID ARTERY?
- facial to angular
- superficial temporal
- transverse facial
What are the branches of the INTERNAL CAROTID ARTERY?
- supratrochlear
- supraorbital
The superficial temporal and the maxillary v. drain into the retromandibular v. Where does the retromandibular drain and what other veins drain there as well?
- Posterior branch and the AURICULAR v. drain into the external jugular
- Anterior branch and FACIAL vein drain into the internal jugular v.
helix
outermost rim of tissue
scaphoid fossa
the furrow between the helix and antihelix
tragus
anterior to the external auditory meatus (“goat”)
antitragus
projection superior to the lobule
concha
leads to external acoustic meatus
external acoustic meatus
bony and firocartilagenous passage
tympanic membrane
boundary between external ear and middle ear
What is the function of the MIDDLE EAR?
mechanically transfers acoustic energy from the tympanic membrane to the oval window of the inner ear
What are the 3 auditory ossicles?
malleus (hammer), incus (anvil), stapes (stirrups)
What is the function of the AUDITORY CANAL and what muscles make it move?
- function: equalizes pressure of the middle ear with atm pressure
- contraction is due to muscles of soft palate
The plane is taking off and you feel pressure in your ears. Which part of the body can you use to make your ears “pop”?
the AUDITORY CANAL
What does the STAPEDIUS MUCSLE do and what is its innervation?
prevents excessive movement of the stapes (dampens loud sounds); innvervated by CN VII
What does the TENSOR TYPANI MUSCLE do, where does it attach and what is it innervated by?
decreases the amplitude of oscillations on tympanic membrane (dampens loud sound), attaches to malleus and innervated by CN V3 (mandibular)
A man was rude to his girlfriend so she hit him on the side of his head with her hair dryer. The man passes out but regains consciousness a few seconds later. The man ends up at the ER when he passed out again suddenly, indicating epidural hemorrhage. Which suture junction of the head did the girlfriend hit and what artery was pierced?
- the PTERION junction [where normally, the meninges adheres to cranium]
- the middle meningeal artery [it was pierced when a piece of skull fracture pierced the vessel, creating pressure within the meninges]
What are the membranous intervals between cranial bones of a newborn called?
Fontanelles
Which two craniometric points are the locations of the ANTERIOR FONTANELLE and the POSTERIOR FONTANELLE, respectively?
- Anterior fontanelle: BREGMA
- Posterior fontanelle: LAMBDA
Patient arrives to the ER after being rescued from a car accident and X-rays show a cracked along the zygomatic arch and nasal bridge at the nasofrontal and frontomaxillary sutures, stopping at the sphenoid bone posteriorly. There is tenderness upon palpation and separation of the frontozygomatic suture. What does this patient have?
a La Fort fracture (type III)
What is located in the CONNECTIVE TISSUE of the scalp?
nerves and blood supply
A girl with very long hair was riding an ATV. She wasn’t wearing a helmet and when she pressed on the gas pedal to go, her hair got caught in the wheel, pulling her whole scalp off. Where was this separation?
At the LOOSE CONNECTIVE TISSUE layer
A patient comes to the clinic complaining of headaches. He bumped and cut the top of his head on a hanging light and a day or two later, he got a headache that wouldn’t go away. You suspect a bacterial infection. Where do you think this infection is located? What would you prescribe?
the infection traveled into the “DANGEROUS AREA” of the scalp into the LOOSE CONNECTIVE TISSUE layer through emissary veins; it probably ended up in the CSF and meninges; GO TO THE ER IMMEDIATELY
A knife-juggling circus performer comes to the ER after a knife cut the top of his head just laterally and perpendicular to the sagittal suture. Why is the wound gaping and why is it bleeding so much?
- gaping is due to occipitofrontalis muscles pulling the apopneurosis from either side
- the blood vessels that were lacerated in the scalp have tough, fibrous connective tissue surrounding them, making it hard for those vessels to contract
This guy you have a crush on has the cutest dimples. To compliment him in the nerdiest way possible, your pickup line is “Oh hey, I really like your well-defined _____ muscles”
risorius
You are attending a murder mystery dinner and someone is giving you a look of disdain, raising his eyebrow and then talking about you behind your back. You are above that, however you think that he may be the murder. Which main muscle did he use to look at you in that awful way?
corrigator supercilii
Cool party trick: I can wiggle my ears with my ____ muscles.
auricular
Yum! A grilled cheese sandwich. You take a bite then chew with these muscles: ________
temporalis, buccinator, masseter
Which foramen does the facial nerve emerge through?
STYLOMASTOID FORAMEN [near parotid gland]
What does the FACIAL NERVE innervate?
occipitalis (posterior auricular), orbicularis occuli/frontalis (temporal), platysma (cervical), [facial nerve goes through parotid gland]
A patient presents with a droopy eye and can only smile and wrinkle his brow on his right side. Which nerve was injured? Where? And what is his condition?
Facial nerve was injured distal to stylomastoid foramen; he has Bell’s Palsy
A patient presents with a sudden dizziness, a droopy eye and he can only smile on one side of his face. However, when he looks up he can wrinkle his brow. Which nerve was injured? Where/why? What is his condition?
Facial nerve; thrombus on jugular vein of one side caused nerve damage; person can wrinkle forehead because left/right CN VII upper motor neurons cross-innervate at this point; the patient had a STROKE
A patient complains that she has sudden extreme pain in her chin, which her sister tells her looks like a twitch. Which dermatome is affected and which nerve innervates it? What is your diagnosis?
the Mandibular dermatome (Trigeminal V3)
-Trigeminal neuralgia (Tic Douloureux)
What is a special characteristic of the emissary veins that allows infectious agents to travel easily through them to the meninges?
they have NO VALVES
A patient presents with Bell’s Palsy symptoms and says that it sounds like everyone is yelling! Which nerve is affected and where does it innervate to cause this problem?
Facial nerve; innervates the stapedius muscle which usually adjusts to dampen sound
You have numbness on your chin and on the top, anterior portion of your ear. You also complain that everyone seems to be yelling when they speak. What nerve is most likely damaged and what is it innervating to cause this problem?
Trigeminal V [Mandibular branch]; innervating TENSOR TYMPANI MUSCLE which usually adjusts to dampen sound
The coroner is doing an autopsy and notices something in the neck region that suggests that this homicide case patient was strangled. What did he notice?
the hyoid was broke {the hyoid protects the trachea}
A patient presents with a stab wound in ZONE 2, causing her chin to deviate to the left side of her body and she cannot look to the right. Which structure was definitely lacerated and on which side?
Her ACCESSORY NERVE on the left side, which innervates her STERNOCLEIDOMASTOID MUSCLE
What is in the SCALENE GAP?
brachio plexus and SUBCLAVIAN ARTERY
You are looking to identify a vessel but you can’t figure out what it is because there are two next to each other. One is (A) in front of the ANTERIOR SCALENE and (B) one is between the anterior scalene and the MIDDLE SCALENE. What are they, respectively?
(A) SUBCLAVIAN VEIN
(B) SUBCLAVIAN ARTERY
Where is the PLATYSMA located?
in the SUPERFICIAL CERVICAL FASCIA
A patient comes into the dentist complaining of a molar toothache, fatigue, low blood pressure and dizziness. The dentist notices a posterior molar abscess and thinks the patient might have an infection, because he notices that he has “pinpoint pupils”. What is the path of this infectious agent and what nerves are affected? And why must this patient be rushed to the ER immediately?
The pathogen ate through the BUCCOPHARYNGEAL FASCIA, entering the RETROPHARYNGEAL SPACE; in this space is the SYMPATHETIC CHAIN, containing the SNS nerves; the infectious agent could have gone as far caudally as the T1-T2 level [where the ALAR FASCIA and buccopharyngeal fascia fuse]
-don’t want infection to go into the pleural space (thorax)
A patient’s MRI suggests a clot in his JUGULAR VEIN and so he needs surgery. The surgeon opens him up and sees two vessels, one more lateral and one more medial. Which one contains the clot? Through which fascial layer did he cut?
lateral; through the DEEP CERVICAL FASCIA (superficial layer and pretracheal layers)
During a thyroid surgery, the surgeon must accidentally cuts a nerve. Post-op, the patient talks with a hoarse voice. Which nerve did the surgeon cut?
RECURRENT LARYNGEAL that innervates the voice muscles
What fills the spaces between the various layers of DEEP CERVICAL FASCIA? And what are these spaces called? Why?
LOOSE AREOLAR, CONNECTIVE TISSUE; these spaces are POTENTIAL SPACES because they can fill up with infectious material, causing swelling and potentially breathing problems
Some guys are part of a Fight Club and one decides to bring a knife to a fight, deciding that he will kill his opponent [he’s been watching too many Quentin Tarantino movies]. In which ZONE should he stab his opponent and why?
ZONE 1 because the most vital nerves, arteries (carotid/sublavian), veins (jugular/subclavian) going to the brain are located there
Some guys are part of a Fight Club and one decides to bring a knife to a fight, deciding that he will kill his opponent [he’s been watching too many Quentin Tarantino movies]. During the fight, the guy knifes his opponent in the deadliest of zones (ZONE 1), causing him to immediately gasp for air. What structure did the knife pierce through and what resulted?
it pierced through the CERVICAL PLEURA, causing a PNEUMOTHORAX
A patient comes into the ER with a deep stab wound to the side of the neck. The patient’s chin deviates to that side and he is loosing a lot of blood. Which muscle and vessel did the knife cut though?
the SCM and the INTERNAL JUGULAR VEIN (posterior to SCM)
A patient was shot in the neck. The surgeon wants to perform exploratory surgery to find the bullet. In which zones can he do this safely?
ZONE II only
CN I
Olfactory n.
F: special SENSORY–smell
CBs: olfactory epithelium
P: ethmoid bone–cribriform plate
What happens when there is a fracture to the cribriform plate?
olfactory nerve is damaged and anosmia results
anosmia
loss of smell
CN II
Optic n.
F: special SENSORY–vision
CBs: retina
P: sphenoid bone–optic canal
What happens if there is eyeball trauma? What nerve is damaged?
Optic (CN II); results in anopsias
Anopsias
visual field defects
CN VIII
Vestibulocochlear n.
F: special SENSORY–hearing and balance
CBs: spiral ganglion (COCHLEA), vestibular ganglion
P: temporal-internal acoustic meatus
What nerve is impacted if a tumor causes dizziness or hearing loss?
vestibulocochlear (CN VIII)
CN III
Oculomotor n.
F: somatic MOTOR (GSE)–eye movement
CBs: upper midbrain–oculomotor nucleus
P: sphenoid bone–superior orbital fissure
What does the OCULOMOTOR NERVE innervate?
levator palpebrae, superior rectus, inferior rectus, medial rectus, inferior oblique
Ptosis
eyelid droop due to paralysis of levator palpebrae m. (CN III–oculomotor)
A patient presents with a pupil that is fixed and dilated after an aneursm of the posterior cerebral artery. Which nerve was damaged?
CN III oculomotor
CN IV
Trochlear n.
F: somatic MOTOR–eye movement
CBs: lower midbrain–trochlear nucleus
P: sphenoid bone-superior orbital fissure
Which nerve emerges near the median plane at the junction of the midbrain and the pons?
CN III oculomotor
What does the TROCHLEAR NERVE innervate?
Superior oblique m.
What is it called when someone is not able to look down when the eye is adducted? Which nerve/muscle are damaged?
Diplopia; CN IV-trochlear nerve and superior oblique muscle of the eye
CN VI
Abducent n.
F: somatic MOTOR–eye movement
CBs: pons–abducent nucleus
P: Sphenoid bone-superior orbital fissure
What does the ABDUCENT NERVE innervate?
lateral rectus muscle
What happens when one has horizontal diplopia, impaired eye abduction and a tendency for the eye to turn medially?
CN VI-Abducent nerve is damaged; possibly due to fracture of base of skull or cavernous sinus injury
CN XI
Accessory n.
F: branchial MOTOR–head and neck movement
CBs: spinal cord–anterior horn of cervical region
P: occipital bone–entry: rootlets via foramen magnum and exit: jugular foramen
What does the ACCESSORY NERVE innervate?
Sternocleomastoid and trapezius muscles
What is a possible clinical presentation if a patient has a deep neck laceration, causing weakness in turning head to one side and weakness in shrugging shoulders? What nerve would be affected?
CN XI –Accessory
CN XII
Hypoglossal n.
F: somatic MOTOR–swallowing, sucking, chewing, tongue protrusion
CBs: medulla–hypoglossal nucleus
P: occipital bone–hypoglossal canal
What does the HYPOGLOSSAL NERVE innervate?
All intrinsic tongue muscles; all extrinsic tongue muscles, except the palatoglossus (CN X)
A patient has a laceration on his neck, causing his protruded tongue to deviate toward the side of injury. Which nerve is injured?
CN XII–hypoglossal
CN V
Trigeminal n.
CN V1
F: somatic SENSORY–skin of forehead, scalp, mucous membranes (nasal)
CBs: Trigeminal (semilunar) ganglion
P: Sphenoid bone–superior orbital fissure
A patient underwent gallbladder surgery and was placed under general anesthesia. When the patient awoke, he complained of no pain but also little touch sensation on his forehead. What nerve was injured?
CN V1 (Opthalmic)
CN V2
F: somatic SENSORY–skin, upper lip, skin over prominence of cheek, palate, maxillary sinus
CBs: Trigeminal ganglion
P: sphenoid bone–foramen rotundum
A man comes into the neurologist complaining of intermittent, painful facial ticks. What is this condition called and what nerve is most likely damaged?
Tic douloureaux; CN V2 (Maxillary)
CN V3
F: SENSORY [skin of lower jaw, mucosa on anterior 2/3 of tongue] and MOTOR [branchial motor–chewing and swallowing]
CBs: sensory=trigeminal ganglion; motor=pons–motor nucleus of V
P: sphenoid bone–foramen ovale
A patient underwent lap band surgery and was placed under general anesthesia. When the patient awoke, he complained of no pain but also little touch sensation on his chin. What nerve was injured?
CN V3 (Mandibular)
What muscles do CN V3 innervate?
muscles of mastication (temporalis, lat & med. pterygoids, masseter), tensor veli palatini, tensor typani, myolyoid, digastric (anterior belly)
A patients has a bacterial infection and inflammation of her lower jaw, complaining of difficulty chewing. Which nerve was damaged?
CN V3 (Mandibular)
CN VII
Facial n.
F: somatic SENSORY, special SENSORY & MOTOR (branchial motor–facial expression)
CBs: sensory = geniculate ganglion; motor = pons–motor nucleus of VII
P: Temporal bone: entry = internal acoustic meatus; exit #1 [somatic sens/motor] = stylomstoid foramen; exit #2 [special sensory–taste] = petroympanic fissure
Which muscles does CN VII innervate?
muscles of facial expression [platysma, buccinator, frontalis, occipitalis, orbicularis oculi, orbicularis oris], stapedius, stylohyoid, digastric (posterior belly)
CN IX
Glossopharyngeal n.
F: somatic, visceral and special SENSORY & branchial MOTOR
CBs: sensory = Superior ganglion of IX; motor=medulla–nucleus ambiguos
P: temporal bone/occipital bone–jugular foramen
What muscle does the glossopharyngeal nerve innervate?
stylopharyngeus muscle
Dysphagia (and injured nerve)
difficulty swallowing (CN IX)
dysarthria (and injured nerve)
difficulty speaking due to anesthesia of soft palate (CN IX)
If the patient cannot taste food from the posterior 1/3 of her tongue, which nerve is injured?
CN IX–glossopharyngeal
CN X
Vagus n.
F: somatic, visceral, special (taste from epiglottis) SENSORY & branchial MOTOR (speech)
CBs: somatic sensory = superior ganglion of X, visceral/special sensory = inferior ganglion of X, motor=medulla-nucleus ambiguus
P: temporal bone/occipital bone–jugular foramen
What visceral sensory functions does the VAGUS NERVE have? (GVA)
stretch receptors and chemoreceptors in/near aortic arch; muscles/mucous membrane sensation
What somatic sensory functions does the VAGUS NERVE have? (GSA)
sensory from pharynx, larynx, external ear, external auditory canal, tympanic membrane (ext. surface), meninges in posterior cranial fossa
What muscles does the VAGUS NERVE innervate?
- skeletal muscles of soft palate (except stylopharyngeus–CN IX and tensor veli palatini–V3)
- pharyngeal constrictors
- levator veli palatini
- salpingopharyngeus
- palatopharyngeus
- palatoglossus
- cricothyroid (ext. laryngeal n.)
- muscles of larynx (recurrent laryngeal n.)
What is the action of the OCULOMOTOR nerve?
sphincter pupillae muscle–>pupil constriction
Ciliary muscle–> lens accommodation for near vision (somatic PNS innervation!)
mydriasis (and corresponding nerve damage)
pupil dilation; CN III oculomotor nerve damage to sphincter pupillae muscle
What occurs if there is injury to CN VII distal to stylomastoid foramen?
Facial muscle paralysis
What occurs if there is injury to CN VII proximal to branching off of chorda tympani?
facial muscle paralysis, loss of taste (anterior 2/3s of tongue), loss of salivation from sublingual and submandibular glands
What occurs if there is injury to CN VII distal to geniculate ganglion?
facial muscle paralysis, loss of taste (anterior 2/3s of tongue), loss of salivation from sublingual and submandibular glands, hyperacusis (due to stapedius muscle paralysis)
What occurs if there is injury to CN VII with involvement of greater petrosal nerve?
facial muscle paralysis, loss of taste (anterior 2/3s of tongue), loss of salivation from sublingual and submandibular glands, hyperacusis (due to stapedius muscle paralysis), loss of taste (palate), loss of lacrimation (dry eye)
What glands does CN VII innervate?
lacrimal gland and salivary glands (except parotid)
What is the mechanism of signal transmission from the FACIAL nerve to the LACRIMAL gland?
Pre-gang CBs: pons–superior salivatory nucleus;
Goes through nervous intermedius and geniculate ganglion via greater petrosal n. to nerve of pterygoid canal
Post-gang CBs: synapse at pterygopalatine ganglion then travels via zygomaticotemporal (V2) and lacrimal (V1) nerves to the lacrimal gland and mucosa of nasal cavity, nasopharynx and palate
What does injury to the LACRIMAL GLAND result in?
Dry cornea
What is the mechanism of signal transmission from the FACIAL nerve to the SALIVARY (not parotid) gland?
Pre-gang CBs: pons–superior salivatory nucleus;
Goes through nervous intermedius (VII) and geniculate ganglion (VII) via chorda tympani (VII) which joins with lingual n (V3)
Post-gang CBs: synapse at submandibular ganglion (attached to V3) to cause salvation
What gland does the GLOSSOPHARYNGEAL nerve innervate?
parotid gland
What is the mechanism of signal transmission from the GLOSSOPHARYNGEAL nerve to the PAROTID gland?
Pre-gang CBs: medulla–inferior salivatory nucleus; exits brain with CN IX fibers then passes through tympanic n. and lesser petrosal n.
Post-gang CBs: otic ganglion (attached to V3) via auriculotemporal n. to parotid–>salvation
What glands/systems does the VAGUS nerve innervate?
smooth muscle and glands of gastrointestinal tract, pulmonary and CV systems
What is the mechanism of signal transmission from the VAGUS nerve to its respective glands?
Pre-gang CBs: medulla–dorsal motor nucleus of X travels with CN X
Post-gang CBs: autonomic ganglia near/winith walls of target organ–>various responses depending on organ
OLFACTORY PLACODES
paired disks of thickened surface ectoderm that form the olfactory epithelium in nasal cavity; associated with forming telencephalon
EPIPHARYNGEAL PLACODES
not distinct; contribute neurons to sensory ganglia of CN V, VII, IX, X; dorsal to pharyngeal grooves 1 and 3
FRONTONASAL PROMINENCE
cranial to developing forebrain between optic vesicles; filled with mesenchyme; where olfactory placodes are located on surface of this prominence
At what embryonic age do the precursors of the head and neck structures appear?
early 4th week of development
PHARYNGEAL ARCHES
paired elevations on either side of the embryo at the level of the pharynx; 5 pairs develop–1-4 are external and 6 is internal
What fills the PHARYNGEAL ARCHES? What type of tissue lines them on the outside? On the inside?
- mesenchyme tissue
- ectoderm
- endoderm
What types of tissue are ectoderm/endoderm?
epithelial tissue
Why is PHARYNGEAL ARCH 1 special?
subdivided into MAXILLARY (cranial) and MANDIBULAR (caudal) prominences
What pharyngeal arches are visible by the 22nd week of development?
Arch 1 and Arch 2
What are the most significant structures associated with head and neck development?
PHARYNGEAL ARCHES
PHARYNGEAL GROOVES
visible externally on the side of the embryo between the pharyngeal arches; floor is outer, surface ectoderm
How many PHARYNGEAL GROOVES are there?
3
What is the CLOSING PLATE?
in pharyngeal groove: ectoderm, thin mesenchyme layer (between pharyngeal arch), endoderm of pharyngeal pouch
What structures are found within a PHARYNGEAL ARCH? (5)
(1) cartilaginous component
(2) muscle component (paraxial mesoderm-derived)
(3) vascular component (aortic arch)
(4) nervous component (CN)
(5) connective tissue (loose mesenchyme-derived)
Describe how the PITUITARY forms.
;
What signs/symptoms would indicate that your patient might have a CRANIOPHARYNGIOMA?
;
What structures are derived from the CARTILAGE of pharyngeal arch 1?
MECKEL’S CARTILAGE, SPHENOMANDIBULAR LIGAMENT, MALLEUS, INCUS
What structures are derived from the CARTILAGE (REICHART’S CARTILAGE), in pharyngeal arch 2?
STYLOHYOID LIGAMENT, STYLOID PROCESS, upper 1/2 of HYOID BONE (lesser horns), STAPES
What structure is derived from the CARTILAGE in pharyngeal arch 3?
lower 1/2 HYOID BONE (greater horns)
What structures are derived from the CARTILAGE of pharyngeal arch 4/6?
LARYNGEAL CARTILAGES (thyroid, cricoid)
What is the difference between a cyst, a sinus and a fistula?
’
What is the developmental fate of the FIRST PHARYNGEAL GROOVE?
EXTERNAL AUDITORY MEATUS
What is the developmental fate of the 2, 3, 4 and 6th PHARYNGEAL GROOVES?
PA II grows caudally and fuses with lateral body wall adjacent to cardiac prominence (grows cranially); therefore the 2nd/3rd GROOVES temporarily form the CERVICAL SINUS, which eventually disappears
Where is the most likely place to find a BRANCHIAL CYST in a patient?
lateral side of neck; accounts for 2% of all non-thyroid neck masses and are fluid/semi-solid material (cysts)
Between what two epithelial surfaces does a BRANCHIAL FISTULA tract?
pharynx (endoderm) and the lateral side of the neck (ectoderm)
Where is the PHARYNX and from what cell type is it derived?
dilated and elongated at the cranial end of the foregut; derived from endoderm
What are PHARYNGEAL POUCHES?
outpouchings of the pharynx that extend laterally between pharyngeal arches; made of endoderm (part of CLOSING PLATE)
Where does the mesenchyme tissue between the inner and outer layers of epithelium (pharyngeal arches) originate from?
NEURAL CREST CELLS [from paraxial mesoderm]
OROPHARYNGEAL MEMBRANE
area of ectoderm-endoderm fusion; located at the cranial end of the pharynx and separates it from the forming oral cavity; the membrane ruptures by day 24-26
ORAL CAVITY
mouth; space ventral to oral membrane; formed as result of growth of PHARYNGEAL ARCH 1 and FRONTONASAL PROMINENCE
STOMADEUM
primitive ORAL CAVITY
What is the primitive structure that precedes the formation of the pituitary gland?
RATHKE’S POUCH; dorsal diverticulum and evaginates cranially near the junction of the oral cavity and pharynx
HEAD MESODERM
paraxial mesoderm in the head region; non-segmented; origin of skeletal muscle and vascular endothelium in pharyngeal arches
OCCIPITAL SOMITES
first four somites (segmented); their dermatome and myotome components contriubute to formation of head and neck structures
What do neural-crest-derived mesenchyme form in the PHARYNGEAL ARCHES?
skeletal tissue, fibrous connective tissue, vascular smooth muscle and components of peripheral nervous system
What 2 types of highly patterned cellular signaling centers in brain formation? Which genes are employed?
- FOREBRAIN (prosencephalon) & HINDBRAIN (rhombencephalon)
- HOX genes
What is the fate of LOOSE MESENCHYME in the pharyngeal arches?
FIBROUS CONNECTIVE TISSUE (fascia)
What do centrally neural crest-derived mesenchyme cells become when they are condensed?
rod-shaped CARTILAGE (or non-cartilage structures like bones, tendons, etc.)
In each pharyngeal arch, cells aggregate into vascular tubes that will eventually make up an ________
AORTIC ARCH: PA1/2= external carotid PA 3= common/internal carotid PA 4 = left aorta, right subclavian PA 6 = pulmonary arteries, ductus arteriosis
What structure grows into each pharyngeal arch?
CRANIAL NERVE
What is MECKEL’S CARTILAGE?
cartilage of the 1st pharyngeal arch in the MANDIBULAR portion
What skeletal components are derived from the non-cartilaginous [neural crest-derived] MESENCHYME of pharyngeal arch 1, maxillary portion? (8)
maxilla, zygomatic, squama of temporal, nasal, lacrimal, palatine, vomer, ala of sphenoid greater wing, pterygoid plates of sphenoid
What CRANIAL NERVE innervates arch 1?
CN V
What skeletal muscles are derived from the non-cartilaginous [paraxial-derived] MESENCHYME of pharyngeal arch 1? (7)
- muscles of mastication=temporalis, masseter, pterygoids
- mylohyoid
- tensor tympani
- tensor palati
- digastric (anterior belly)
What are derived from the non-cartilaginous MESENCHYME and PARAXIAL MESODERM in pharyngeal ARCH 2?
- muscles of facial expression
- STAPEDIUS
- STYLOHYOID
- DIGASTRIC (posterior belly)
What CRANIAL NERVE innervates arch 2?
CN VII
What structures are derived from non-cartilaginous MESENCHYME and PARAXIAL MESODERM in pharyngeal ARCH 3?
STYLOPHARYNGEUS MUSCLE
What CRANIAL NERVE innervates arch 3?
CN IX
What structures are derived from non-cartilaginous MESENCHYME and PARAXIAL MESODERM in pharyngeal ARCH 4/6?
- *skeletal muscle derived from OCCIPITAL SOMITE MYOTOMES (1-4)
- laryngeal muscles
- pharyngeal constrictors
- palaglossus
- palatopharyngeaus
- salpingopharyngeus
- levator palati
- muscles of upper 1/3 of esophagus
What CRANIAL NERVE innervates arch 4? From what somites are they derived?
- CN X (superior laryngeal nerve)
- occipital somites 1 and 2
What CRANIAL NERVE innervates arch 6? From what somites are they derived?
- CN X (inferior laryngeal nerve)
- occipital somites 3 and 4
What is a key presentation of a patient with a developmental PHARYNGEAL GROOVE ABNORMALITY?
lateral side of neck, ventral to sternocleiomastoid
What is the result of a DUPLICATION of the 1st pharyngeal groove?
blind pouch or a fistula tracking from external auditory meatus to side of cheek
What is a TONSILAR FISTULA?
if the fistula involves the 2nd pharyngeal groove and tracts to the tonsilar fossa through the carotid birfurcation
If a FISTULA tracks to the superior part of the larynx and pierces through the thyrohyoid membrane, which pharyngeal groove does it involve?
3rd pharyngeal groove
What is a PERSISTANT CERVICAL SINUS?
an opening on the lateral side of the neck that opens onto the epithelium of origin (blind pouch lined with epithelium)
Which type of embryonic cells are developmental PATTERN BARERS for the head region?
cells determined to become FIBROUS CONNECTIVE TISSUE (loose mesenchyme-derived cells)
Which type of embryonic cells are developmental PATTERN READERS for the head region?
cells determined to become MYOBLASTS and VASCULAR ENDOTHELIAL CELLS (paraxial mesoderm-derived)
What kind of patterning do the HOX GENES set up in the head region? Where is this pattern first established?
- AXIAL patterning
- Midline in RHOMBENCEPHALIC SIGNALING CENTER
Which signaling center sets up the plan for arrangement of structures in the upper face and inner ear?
PROSENCEPHALIC SIGNALING CENTER
Where does pharyngeal arch MESENCHYME originate from?
PARAXIAL MESODERM and NEURAL CREST CELLS
What are the major features and primary causes of DiGEORGE SYNDROME?
aka thymoparathyroid aplasia; interstitial deletions of chromosome 22 in TBX1 gene region causing INSUFFICIENT NEURAL CREST CELL migration
[heart problems, minor craniofacial defects, low-set ears, hypoplastic mandible, cleft palate, hypoparathyroidism, etc.]
What are the 3 major types of SALIVARY GLANDS?
PAROTID, SUBMANDIBULAR, SUBLINGUAL
What are the primodia of the salivary glands at 6-8 weeks look like?
solid epithelial cords of ORAL ECTODERM that invaginate into the adjacent mesenchyme
What do the EPITHELIA CORDS of the salivary glands form?
ducts and secreting elements
What does the mesenchyme of the SALIVARY GLANDS form?
fibrous connective tissue septa and a capsue
From what does the THYROID GLAND begin to form? On what day of development?
forms as midline diverticulum from floor of PHARYNX between pharyngeal arches 1 and 2; day 22
FORAMEN CECUM
in adults; the blind sac is the site of THYROID DIVERTICULUM (connected to pharynx)
THYROGLOSSAL DUCT
hollow THYROID DIVERTICULUM (transiently connected to pharynx)
When does the THYROID DIVERTICULUM become bilobed?
Day 28 of development
How does the THYROID get to its final position in the body?
displacement (descent) of thyroid caudally from pharynx into neck; finished by week 7-8; thyroglossal duct loses connection with pharynx
How would you diagnose a patient presenting with a midline, oblong neck cyst tracking from the THYROID to the base of the TONGUE?
TYROGLOSSAL DUCT CYST; caused by lack of ablation of thyroglossal duct in development
What does the FIRST PHARYNGEAL POUCH form?
the epithelial lining of the AUDITORY TUBE and MIDDLE EAR CAVITY (external auditory meatus)
What does the SECOND PHARYNGEAL POUCH form?
the covering epithelium and crypts of the PALATINE TONSILS
What does the THIRD/FOURTH PHARYNGEAL POUCH form?
- DORSAL EXTENSION=the pharynx are displaced caudally and becomes the INFERIOR PARATHYROID GLANDS
- VENTRAL EXTENSION=forms THYMUS GLAND
What does the FOURTH [FIFTH] PHARYNGEAL POUCH form?
DORSAL=the pharynx is displaced caudally and becomes the SUPERIOR PARATHYROID GLANDS
VENTRAL=ULTIMOPHARYNGEAL BODY
-mesenchyme filled with neural crest-dervied lymphocytes–> C-CELLS that will produce CALCITONIN in thyroid gland
