Session 5 Flashcards
1
Q
Describe embryo at 4 weeks
A
No face yet discernible
Head and neck take up almost half of body
Embryonic head is complex but follows similar segmental pattern
Each segment contains structures from various different systems
2
Q
What are the bulges in embryonic neck called
A
Pharyngeal arches
3
Q
What is on the outside and inside of a pharyngeal arch
A
Outside = ectoderm
Inside = endoderm
4
Q
Pharyngeal arch contains
A
Artery- mesoderm, one of aortic arches
Cartilage bar- associated muscles, supports arch
Cranial nerve- each arch has a different nerve, motor to muscles associated with cartilage
5
Q
Arch 1 features
A
6
Q
Arch 2 features
A
7
Q
Arch 3 features
A
8
Q
Arch 4 + 6 features
A
9
Q
Depression on outside is called
A
10
Q
Depression on inside is called
A
11
Q
What does the first cleft form
A
Tympanic membrane —> eternal acoustic meatus
12
Q
What happens to clefts 2-6
A
Caudal border of second arch grows over more caudal arches and they disappear
13
Q
What does the first pharyngeal pouch form
A
Tubotympanic recess —> Eustachian tube
Middle ear cavity
14
Q
What does the second pharyngeal pouch form
A
Palatine tonsil
15
Q
What does the third pharyngeal pouch form
A
Thymus and inferior parathyroid
16
Q
Branchial/pharyngeal abnormalities
A
Cysts, sinuses and fistulas
17
Q
Branchial cysts, sinuses and fistulas
A
Cyst = enclosed
Sinus = communicates with skin
Fistula = connects skin with pharynx
18
Q
Branchial sinuses are usually found
A
As pits near the ear
19
Q
Branchial cysts are usually found
A
Anterior to SCM in anterior triangle of neck
20
Q
Features of fetal alcohol syndrome
A
Neural crest cells
Under developed jaw
Ears low set
Flat mid face
Small head
21
Q
How does ear form
A
22
Q
Innervation of the anterior 2/3 of tongue
A
Sensation from trigeminal
taste from facial
23
Q
Innervation of posterior 1/3 of tongue
A
Sensation and taste from glossopharyngeal
24
Q
Muscles arise from
A
Somites at the level of hypoglossal nerve
25
What separates the two parts of tongue
Sulcus terminalis
26
How does the thyroid gland develop
Thyroid diverticulum originates form Foramen cecum
Thyroglossal duct breaks down
Thyroid gland and cartilage is formed
27
Congenital problems with thyroid gland development
Failure of thyroglossal duct to break down can result in cysts and fistulae opening at foramen caecum
Ectopic thyroid gland tissue can sometimes be found anywhere along path of descent
28
How to detect a cyst or fistula at foramen caecum
Connected to tongue, stick tongue out = elevate the lump
29
Collectively, the pharyngeal arches, their grooves (clefts) and pouches are known as the
Pharyngeal apparatus
30
Rearrangement of developing structures explains why
Recurrent laryngeal nerve of faves becomes looped under the arch of the aorta on left side fan subclavian artery on right side
31
Facial skeleton arises from the
Frontonasal prominence and 1st pharyngeal arch
32
What does the fourth pharyngeal pouch form
Superior parathyroid and C cells of thyroid
33
Face develops from which 5 building blocks
Frontonasal prominence, two maxillary prominences and two mandibular prominences
34
First evidence of face development is the
Appearance of a depression in the ectoderm on the ventral aspect of the head- stomadaeum (site of future mouth)
35
Frontonasal prominence will form the
Forehead, bridge of nose, upper eyelids and centre of upper lip
36
Laterally paired maxillary prominences form the
Middle third of the face, upper jaw and most of lip and sides of nose
37
Paired mandibular prominences form
Lower third of face, including lower jaw and lip
38
First evidence of nose formation is appearance of
Two ectodermal thickenings - nasal placoderms
On ventrolateral aspect of Frontonasal prominence
39
What is a placode
Area of ectoderm that starts to thicken and differentiate itself from the surrounding tissue and give rise to sensory structures
40
Future ear develops from what placode
Otic
41
Deepening nasal pits are separated by
Oronasal membrane which disappears and the oral and nasal cavities become one continuous space
42
Palate development involves the
Maxillary prominences (merge in midline to form philtrum and primary palate) and medial nasal prominences
Fusion of palatal shelves form secondary palate and separates nasal cavity from oral cavity
43
What must happen so the palatal shelves can fuse (and nasal septum)
Tongue must drop down
44
Cleft lip arises from
Failure of fusion of medial nasal prominence and maxillary prominence
45
Cleft palate is when
Failure of fusion of medial nasal prominence and maxillary prominence
AND
Failure of palatal shelves to meet in midline
(Genetic and environmental)
46
Clefts of the lip and palate diagnosis
Antenatal with ultrasound, or after delivery
Difficulties with feeding or speech development, cosmetic
47
Clefts treatment
Surgery
Cleft lips- around 3 months (for cosmetic reasons)
Cleft palate- 9-12 months (specialist feeding techniques can be used up until this point)
48
From which pharyngeal arch are the maxillary and mandibular prominences formed
First arch
49
Major sensory branches from Va
Frontal nerve- supraorbital and supratrochlear nerve (on to forehead)
Nasociliary nerve- eye and skin over nose and tip of nose
50
Major sensory branches from Vb
Infra-orbital nerve (vulnerable in orbital floor fracture)
Superior alveolar nerves (supplies upper teeth and gums)
51
Major sensory branches from Vc
Auriculotemporal nerve (sensory to side of scalp, part of ext ear and TMJ)
Lingual nerve (general sensation from anterior 2/3 tongue)
Inferior alveolar nerve (supplies lower teeth and gums) + mental nerve (both vulnerable in mandibular fractures)
52
CN Va Opthalmic nerve division of trigeminal nerve key branches image
53
Hutchinson’s sign
vesicles on tip of nose- very concerned about eye being affected by shingles
54
Divisions of trigeminal nerve as seen on face
55
CN Vb Maxillary nerve division of trigeminal nerve key branches image
56
CN Vc Mandibular nerve division of trigeminal nerve key branches image
57
Orbital blowout fracture clinical correlation and presentation
Sensory defect on lower eyelid and part of cheek
Numb gums and upper teeth
Infraoribital nerve runs within bone forming floor of orbital
58
Mandibular fracture clinical relevance
Mental nerve exits mental foramen
Mental nerve enters into mandibular canal, becomes inferior alveolar nerve running within bone of mandible
Patch of sensation from lower lip and chin, gum and incisors affected
59
Facial nerve CN VII supplies generally
Motor, special sensory (Taste), parasympathetic
60
Facial nerve specific supplies
Motor (muscles of facial expression and nerve to stapedius)
Special sensory taste (anterior 2/3 tongue)
Parasympathetic to glands (lacrimal, nasal and salivary) (excluding parotid)
61
How to test facial nerve
Muscles of facial expression
62
Facial nerve lesion presentation
Unilateral facial droop +/- reporting symptoms due to absence of other facial nerve functions e.g. altered taste, dry mouth, can’t cry
On examination - whole half of affected side including forehead
63
Causes of facial nerve problems
Lesions in/around internal acoustic meatus & posterior cranial fossa tumours
Basal skull fracture involving Petrous bone
Middle ear disease (inflammation in facial canal, facial nerve palsy)
Parotid disease
64
Types of facial nerve palsy
Bell’s palsy, Ramsay-Hunt syndrome
65
How to diagnosis Ramsay-Hunt syndrome or not
Look for vesicles- a little bit like shingles of facial nerve
Caused by VZ
Vesicles around external ear
66
Facial nerve route
67
Extracranial branches of facial nerve
Temporal
Zygomatic
Buccal
Marginal mandibular
Cervical
Two zebras bit my cock
68
3 branches of facial nerve into Petrous bone
Nerve to stapedius - innervates muscle which dampens vibration of stapes
Greater Petrosal- carries parasympathetic fibres to lacrimal and nasal mucosal glands
Chorda tympani- taste from anterior 2/3 tongue, carries parasympathetic fibres to salivary glands (except parotid)
69
Facial droop key difference between stroke and facial nerve lesion
In stroke:
Forehead sparing- can close eye and raise eyebrows
Brain neural connections between motor cortex and facial nerve nuclei have been damaged
Not a facial nerve lesion
70
Forehead sparing explained
Pathology and injury involving motor pathways anywhere along path from primary motor cortex to where synapse with facial nerve motor nuclei in brainstem
Upper half of Contralateral face spared as has back up from ipsilateral cortex
71
Why would forehead also be affected
Pathology and injury involving facial nerve anywhere from after exit from brain stem and along its route to target tissue
Whole half of ipsilateral face affected
72
CN VIII Vestibulocochlear functions
Special sensory
Cochlea (organ of hearing)
Semicircular canals (organ of balance)
73
presentation and test for CN VIII Vestibulocochlear lesion
Present with- hearing loss, dizziness, tinnitus
Test with- gross bedside hearing test (whisper/finger rub), tuning fork test (Weber’s and Rinne’s)
74
Problems with CN VIII Vestibulocochlear
Vestibular shwannoma (or other posterior cranial fossa tumours)
Occlusion of labyrinthine artery (supplies the nerve)
Base of skull fracture (involving petrous bone)
Brainstem lesions (pons) rare
75
What is Vestibular Schwannoma (acoustic neuroma)
Benign tumour involving Schwann cells associated with vestibulocochlear
Slow growing
Usually unilateral
76
Vestibular Schwannoma (acoustic neuroma) signs and symptoms
Unilateral hearing loss
Tinnitus
Vertigo
Numbness, pain or weakness down one half of face
77
CN IX and X Glossopharyngeal and Vagus nerves route
Arise from medulla
Run through posterior cranial fossa
Exit through jugular foramen
Both carry parasympathetic fibres (to different target tissues)
Enters into carotid sheath - close relationship with internal and external carotid arteries
Glossopharyngeal nerve leaves sheat superiorly, tend to be examined together
78
CN IX Glossopharyngeal roles
Mainly sensory (oropharynx/tonsils/middle ear cavity)
Posterior 1/3 tongue (SS/GS)
1 swallowing muscle
Parasympathetic to parotid gland
Afferents from carotid sinus and body
79
CN X Vagus nerve roles
Motor and sensory
Muscles of larynx/pharynx- including soft palette
Sensory (Larynx/laryngopharynx)
Parasympathetic to many tissues
80
Presentation of patients with CN IX and X Glossopharyngeal and Vagus nerves problems
Difficulty with swallowing (CN X mainly)
Weak cough (CN X)
Difficulties with speech or changes in voice (CN X)
81
Assessment of patients with problems with CN X and CN IX
Speech, swallow and cough assessed
Soft palate movement (ahhh = elevation) and uvula position (CNX) assessed
Gag reflex (IX afferent, X efferent)
82
Problems with CN IX and X Glossopharyngeal and Vagus nerves
RLN branch of CN X (thyroid pathology or surgery, superior thorax/mediastinal pathology)
Pathology or surgery involving carotid sheath structures (e.g. common or internal carotid artery dissection, carotid endartectomy)
Posterior cranial fossa tumours , base of skull fractures (jugular foramen)
Brainstem (medullary) lesions e.g. infarct, MND
83
Key branches of vagus in neck
Right recurrent laryngeal nerve
Left recurrent laryngeal nerve
84
CN XI and XIII Accessory and Hypoglossal pathway
Arise from medulla (accessory nerve also has some contribution from upper cervical spinal nerves)
Runs through posterior cranial fossa
enter into carotid sheath (both leave superiorly in sheath)
- hypoglossal exits and travels towards tongue
- accessory exits and heads towards posterior triangle
85
CN XII Hypoglossal functions
Motor, target tissues = muscles of tongue
86
CN XII Hypoglossal examination and causes for problems
Examine tongue movements and protrusion
Surgery/pathology in proximity to or involving contents of upper carotid health, internal and external carotid arteries e.g. carotid endartectomy
Posterior cranial fossa tumours
Brainstem (medullary) lesions involving the hypoglossal nucleus e.g. brainstem infarct, MS
Can be affected in motor neurone disease
87
Problem with CN XII Hypoglossal
Tongue deviates towards the weakest side
88
CN XI Spinal Accessory pathway and action (and test)
Medulla (cranial roots) and spinal roots
Emerges deep to posterior border of SCM to enter posterior triangle, runs superficially in posterior triangle to reach trapezius
SCM (turn head) and Trapezius (shrug shoulders)
Causes shoulder drop
89
CN XI Spinal Accessory nerve problems
Injury, surgery or pathology involving posterior triangle or structures within
Posterior cranial fossa tumours
Base of skull fractures (jugular foramen)
Brainstem (medullary) lesions e.g. infarct
