Exam 2 - Clinical Scenarios and Other Notes Flashcards
1
Q
Neurocranium vs Viscerocranium
A
Neuro: cartilaginous neurocranium cradles skull in the first 10 weeks, then forms the membranous neurocranium
Viscerocranium: cartilaginous (first branchial arch cartilage - Meckels, second arch - Reicherts, third, fourth, and sixth) and membranous components too (maxillary and mandibular prominence of first branchial arch)
2
Q
Cranioschisis (acrania)
A
Failure of the occipital and parietal bones to completely form or close
Associated with arrested brain development and rudimentary forebrain (anencephaly)
3
Q
Microcephaly vs Macrocephaly
A
Micro: small cranium due to fusion of cranial structures
Macro: enlarged secondary to hydrocephalus
4
Q
Craniosynostosis
A
One or more of the fibrous sutures in an infant skull prematurely fuses by turning into bone, thereby changing growth pattern
5
Q
Development from Morula to Embryo
A
Morula: dense ball of cells
Blastocyst: divided into inner cell mass and hypoblasts
Bilaminar embryo: epiblasts and hypoblasts
Gastrulation occurs at this level to form the embryo
6
Q
Places where mesenchymal cells will not invade:
A
Prochordal plate (mouth) and cloacal membrane
7
Q
At four weeks, the embryo will have:
A
Stomodeum (mouth) surrounded by five facial swellings of the first branchial arch
- includes the frontal, maxillary, and mandibular prominences
8
Q
Buccopharyngeal Membrane
A
Divides the anterior 2/3 and posterior 1/3 of the tongue (supplied by GVE)
9
Q
Development of the face occurs during:
A
Weeks 5-10
10
Q
Maxillary Prominence forms:
A
Lateral parts of the upper lip, jaw, and secondary palate or palatine shelves
11
Q
Mandibular Prominence forms:
A
Lower jaw and lips
12
Q
If the mandibular prominence fails to fuse:
A
Cleft chin
13
Q
Development of the Nasal Cavity
A
- Nasal pits deepen to form primitive nasal cavity
- Medial nasal prominences Duse as intermaxillary process
- Intermaxillary process forms nasal septum and primary palate
14
Q
Formation of the Palate occurs:
A
Weeks 5-12
15
Q
Mid-posterior landmark between the palates:
A
Incisive Foramen (Foramen of Cecum)
16
Q
Formation of the Secondary Palate
A
Formed by shelf-like projections, lateral palatine processes or palatine shelves
appears at week 6
17
Q
Anterior Cleft Deformity
A
Caused by a failure of medial nasal and maxillary swellings to fuse
Can be unilateral or bilateral - if bilateral, will see the intermaxillary prominence in between the two clefts
18
Q
Posterior Cleft Deformity
A
Caused by the palatine shelves not fusing during development
Usually unilateral
19
Q
Cleft Lip vs Cleft Palate
A
Cleft lip is more prominent and occurs more frequently in males
- maternal age may play a role in occurrence
Cleft palate is more frequent in females
no genetic relationship between cleft lip and isolated cleft palate
20
Q
Oblique Facial Cleft
A
Caused by failure of maxillary swelling to merge with its corresponding lateral nasal swelling
Nasolacrimal duct is exposed - may have phonation issues
21
Q
Median Cleft Lip and Bifid Nose
A
Caused by failure of medial nasal prominences to fuse
very rare, may be autosomal recessive
22
Q
Macrostomia vs Microstomia
A
Dysfusion of the maxillary and mandibular swellings
Macro: will have a very wide mouth
23
Q
Agathnia
A
Dysgenesis of the mandibular swelling
- first branchial arch
- position of the auricle
- congenitally deaf
24
Q
Holoprosencephalic
A
Includes cyclopia, cebocephaly, defect of the midface
Weeks 5, 6, 7, and 10
may be associated with fetal alcohol syndrome
25
Formation of the Branchial Arches
Induction of migratory neural crest cells
26
Branchial Arch Nerves
1: CN 5
2: CN 7
3: CN 9
4: CN 10
6: CN 10
**direct relationship between arches and cranial nerves**
27
Blood Supply to the Branchial Arches
An aortic arch artery develops with each arch
Most will atrophy but some will incorporate into adult arterial system
28
First Branchial Arch Fate
Muscles: mastication
Nerve: CN 5
Artery: degenerates
29
Second Branchial Arch Fate
Muscles: mimetic muscles
Nerve: CN 7
Artery: degenerates
Bony structures: stapes, hyoid
30
Third Branchial Arch Fate
Muscles: stylopharyngeus
Nerve: CN 9
Artery: stem of internal carotids
Bony structures: hyoid
31
Fourth Branchial Arch Fate
Muscles: pharyngeal muscles
Nerve: CN 10
Artery: LEFT = aortic arch
RIGHT = subclavian
Bony structures: laryngeal cartilages
32
Sixth Branchial Arch
Muscles: internal larynx
Nerve: CN 10 - RLN
33
Treacher Collins Syndrome
Impaired growth of the midface
Deformities include: small chin, enlarged nose, cleft palate, and possible cleft lip
May have some conductive hearing loss
34
Formation of the Pharyngeal Arches and Pouches occur during:
Early 5th week - Day 31 to be exact...
35
First Branchial Pouch Derivatives
Eustachian tubes, tympanic cavity (**tubotympanic recess**), mastoid air cells, and body of the tongue
36
Second Branchial Pouch Derivatives
Pharyngeal tonsil, palatine tonsil, lingual tonsil, and the root of the tongue
37
Third Branchial Pouch Derivatives
Inferior parathyroid gland, ventral portion of the thymus, tongue
38
Fourth Branchial Pouch Derivatives
Superior parathyroid gland, ultimobranchial body (C cells of the thyroid), and parafollicular cells
39
Pharyngeal Cleft (lateral to the first branchial pouch)
Forms the external auditory meatus (middle ear bones form)
40
Lateral Cervical Sinus or First Pharyngeal Cleft Cysts
Can either be isolated, or seen with external/internal fistulas
41
Aural and Cervical Cysts
Aural: form anterior to the ear (derivative of the first pharyngeal cleft)
Lateral cervical: located anterior to the SCM*
42
First gland to appear in development at 24 days post-fertilization:
Thyroid - forms in the floor of primitive pharynx just caudal to the median tongue bed
43
Pyramidal Lobes
Ductal remnants may persist extending from the isthmus of the thyroid through the hyoid
Along the midline, this is called a pyramidal lobe and occurs in 50% of people
44
Thyroglossal Duct Cysts and Sinuses
May develop from remnants of the early migration of the thyroglossal duct and may include ectopic thyroid tissue
45
Formation of the Anterior 2/3 of Tongue
Lateral lingual swellings (from arch 1) overgrown the tuberculum impar and fuse in the midline
46
Formation of the Posterior 1/3 of Tongue
Develops from overgrowth of the copula (arch 2) by the hypobranchial eminence (arch 3)
47
Line demarcating the anterior and posterior portions of the tongue:
Sulcus Terminalis
48
Innervation of the Tongue
Anterior 2/3: sensory from CN 5, taste fibers from CN 7
Posterior: sensory from CN 9
Motor of the tongue: CN 12
49
Congenital Malformations of the Tongue
Ankyloglossia (tongue tied)
Macroglossia/Microglossia
Cleft tongue/Bifid tongue
50
Early fusion of branchial arches causes deformities in which ages?
First three years of life
51
Landmarks of the Lips
Nasolabial sulcus: lateral corner of nose to angle of the mouth
Philtrum: shallow, midline sulcus between nose and upper lip
Red Margin: red portion of the lips
Labial frenulae: inside of lips to gingivae
52
Lymphatic Drainage of the Lips
Drains directly into the submental and submandibular lymph nodes --> deep cervical nodes
53
Unilateral Diminution of Nasolabial Sulcus
May be indicative of a neurological disorder
54
Skin Cells of the Cheek
Keratinized stratified squamous epithelium
55
Buccal Fat Pad
In infants, provide leverage for sucking
Immediately deep to this is the buccinator muscle (innervated by CN 7)
56
Cells of the Mucosa of the Cheek
Non-keratinized stratified squamous epithelium
57
Relationships in Sublingual Region
In dissection, the submandibular duct will be ABOVE the lingual nerve and the sublingual gland will be lateral
Also pay attention to hypoglossal nerve in this area
58
Innervation to the Sublingual Gland
**very similar to the submandibular gland**
Parasympathetic: superior salivatory nucleus --> CN 7 --> Chorda tympani joins with lingual --> submandibular ganglion --> gland
Sympathetic: superior cervical ganglion --> perivascular plexus
59
Mylohyoid Muscle Problems
Food can get stuck if the muscle is paralyzed
60
Blood Supply and Innervation to Sublingual Gland
Sublingual branch of the lingual artery
61
Palatoglossus Muscle
Muscle of the tongue - arises from posterolateral hard palate
Overlies the palatoglossal fold and elevates the tongue/closes faucial isthmus during swallowing
Innervation: vagus via the pharyngeal plexus
62
Innervation of the Muscles of the Tongue
**all muscles of the tongue EXCEPT the palatoglossus are innervated by the hypoglossal nerve**
63
Paralysis of the Tongue
Unilateral paralysis: atrophy (looks like large bumps on the tongue) and fasciculations of the intrinsic muscles
- tongue will protrude towards the affected side
Bilateral paralysis: airway obstruction, dysarthria, and dysphagia
64
Lymphatic Drainage of the Tongue
Drains primarily into the deep cervical lymph nodes (including the jugulodigastric and juguloomohyoid)
65
Divisions of the Palate
Anterior 2/3: hard, bony part
Posterior 1/3: soft palate
66
Action of the Soft Palate
Closes the pharyngeal isthmus during deglutition and prevents reflux of material into the nasopharynx
67
Tensor Veli Palatini Muscle
Muscle of the palate:
- located anterolateral to the levator palati muscle and auditory tube
- characteristic white, convergent tendon
- Innervation: small branch of mandibular nerve from CN 5
68
Levator Veli Palati Muscle
Muscle of the palate:
- located inferior to the auditory tube
- innervation: vagus nerve via the pharyngeal plexus
69
Paralysis of the Tensor or Levator Palate
Allows the muscles on the non-paralyzed side to pull or deviate the uvula towards the normal (unaffected) side
70
Vessels and Nerves of the Palate
Includes the nasopalatine, greater and lesser palatine vessels and nerves supply the post-incisive hard and soft palate
71
Adenoids
Swelling of the nasopharyngeal tonsils
72
Tonsillectomy
Have to be care not to cut the tonsillar vein - frequently the source of bleeding
Also need to watch out for the glossopharyngeal nerve
73
Lymphatic Drainage from Palatine Tonsil
Directly into the jugulodigastric (tonsillar) nodes
74
Functions of the Nose
Warms and moistens inspired air in addition to acting as an airway
Part of the mucosa contains receptors for olfaction
75
Portions of the Nose
Upper portion: frontal, maxillae, and nasal bones
Lower portion: septal (midline cartilage) and alar cartilages (supports nostrils)
76
Fractures of the Nose
Frequently occur at the junction between the septal cartilage and the ethmoid/vomer bones
Viewed by anterior rhinoscopy
77
Deep Nose Bleeds
Caused by the sphenopalatine portion of the maxillary artery
78
Divisions of the Nasal Cavity
Vestibule: anterior portion, lined with hair
Olfactory region: located in the roof, contains olfactory receptors
Piriform apertures and choanae: anterior and posterior nasal apertures
79
Nasal Congestion
Venous sinuses (swell bodies) in the vestibular region become dilated and engorged with blood during a cold
This will swell the conchae and obliterate air flow through the meatuses
80
Bones of Lateral Nasal Wall
Most important: maxilla, inferior concha, and sphenoid
| But also: nasal, lacrimal, ethmoid, and palatine
81
Ethmoidal Bulla
Forms a bony eminence overlying the middle ethmoidal air cells
82
Hiatus Semilunaris
Crescent-shaped trough anterior/inferior to ethmoidal bulla
Opening for the maxillary sinus located in the posterior 1/3 of the hiatus semilunaris
83
Nasolacrimal Duct
Located in the inferior meatus
When crying, tears will enter the nasal cavity - this is what makes you sniff
84
Nasal Hemorrhage (epitaxis)
Typically occur at the junction of the septal branches of the superior labial and sphenopalatine arteries
This region = Kiesselbach's Area
85
Olfactory neurons are what type of neuron?
Bipolar and located in the olfactory epithelium
86
Innervation of the Nasal Cavity Mucosa
Anterior 2/3: anterior ethmoidal nerve (branch of the nasociliary nerve, V1)
Posterior 1/3: branches of the pterygopalatine ganglion
*these are GVA and autonomic fibers*
87
Nasopalatine Nerve
Innervates mucosa of the gingiva and hard palate near the upper incisors
88
Auditory (pharyngotympanic) Tube
Has both an osseous and cartilaginous region
3-4cm long and usually closed, except during swallowing or yawning
89
Salpingopalatine Fold vs. Salpingopharyngeal Fold
Salpingopalatine = NO underlying muscle
Salpingopharyngeal = formed by the salpingopharyngeus muscle
90
Two most important facial developments:
Paranasal sinuses and dentition
91
Four Paranasal Sinuses
Maxillary, Ethmoidal, Frontal, Sphenoidal
92
Maxillary Sinus Relationships
Superior: orbit
Inferior: molar teeth of maxilla
Posterior: pterygopalatine fossa
93
Maxillary Sinusitis
May originally present as a toothache of the molars
Infections can spread among the frontal, anterior ethmoidal cells, nasal cavity, teeth, and maxillary sinus
94
Transmaxillary Surgery
Maxillary sinus used as a surgical approach to its surrounding structures
95
Cells of the Ethmoidal Sinus
Anterior ethmoidal cells: open into the anterior part of the hiatus semilunaris
Middle ethmoidal cells: open onto the surface of the ethmoidal bulla
Posterior ethmoidal cells: open onto the superior meatus
96
Frontal Sinus
Regarded as displaced anterior ethmoidal cells that invaded the frontal bone
Frontonasal duct drains into either the ethmoidal infundibulum or the frontal recesses of the middle meatus
97
Sphenoidal Sinus Relationships
```
Posterior: pons, basilar artery
Superior: pituitary
Anterior: nasal cavity
Inferior: nasopharynx
Lateral: internal carotid, V1, *cavernous sinus*
```
98
Sphenoidal Sinusitis
Can also get infections in this area that will spread
99
Transphenoidal Surgery
Approaching the area through the sphenoidal sinus versus the maxillary sinus
100
Pterygopalatine Ganglion
Attached to the maxillary nerve (V2) in the fossa and branches into:
1. Vidian nerve (or nerve to pterygoid canal): formed by the merging of deep petrosal and great petrosal nerves
2. Lesser and Greater Palatine nerves: largest branches, conveys GSA, GVA, and GVE fibers to mucosa of the inferior surface of the hard and soft palate
3. Nasopalatine nerve: follows the palatine nerves
101
Parts of the External Ear
Auricle (pinna) and external auditory meatus
Innervation: GSA sensory from auriculotemporal (V3), lesser occipital, great auricular
Blood supply: superficial temporal and posterior auricular artery
102
Parts of the Middle Ear
(also called the tympanic cavity)
Roof of this cavity is formed by the tegmen tympani and includes the three ossicles for sound transmission (this is in the epitympanic space)
Innervation: GVA sensory of CN 9 via tympanic plexus
Blood supply: stylomastoid branch of the posterior auricular artery and the anterior tympanic artery
103
Parts of the Inner Ear
Series of interconnected fluid-filled membranous ducts and sacs - suspended by bony canals and petrous temporal bone
Innervation: two divisions of CN 8 (cochlear and vestibular)
Blood supply: labyrinthine artery off of AICA
104
Sound Conduction
Sound vibrations are conveyed to the inner ear via vibrations of the ossicles and the fenestra vestibuli
Air transmission = external auditory meatus
Bone conduction = bones of middle ear
Fluid conduction = inner ear
105
Auricular Hematoma
Trauma to the pinna may cause hemorrhaging in the subcutaneous tissue
If this isn't evacuated and bandaged, may deform the auricle --> cauliflower ear
106
Furuncle
When cerumen (wax) gets infect, it is very painful due to the close adherence of the skin to the underlying periosteum
107
Layers of the Tympanic Membrane
Outer layer: skin, innervated by GSA fibers for CN 5 and 10
Middle layer: fibrous, pars tensa
- if this layer is absent, pars flaccida
Inner layer: mucous membrane innervated by GVA fibers from CN 9
108
Central concavity of the tympanic membrane is called the ____
Umbo (apex of concavity)
109
Tympanic Membrane Relationships
Supero-posterior: incus, stapes, fenestra vectibuli
Supero-anterior: auditory tube
Infero-anterior: carotid canal
Infero-posterior: fenestra cochleae
110
Otitis Media
Inflammation of the middle ear cavity relatively common in infants and children due to their auditory tubes being more horizontal and impeding drainage from the tympanic cavity
(the tubes move downward in an adult)
111
Fractures of the Petrous Temporal Bone
Severe head trauma may cause a basilar skull fracture such as transverse or longitudinal fractures of the temporal bone
Symptoms: otorrhea, otorrhagia, vestibular disturbances, deafness, or Bell's palsy
112
Important Point about CN 7
IT'S NOT IN THE MIDDLE EAR CAVITY
113
Path of the Facial Nerve
Leaves the brainstem --> nerve travels laterally in the internal auditory meatus --> enters the facial canal
114
Relationships to the Facial Nerve
Cochlea is anterior
| Geniculate ganglion located just above and medial to the promontory of the middle ear cavity
115
Lesions of the Facial Nerve (5)
1. Facial nerve = Bell's Palsy
2. Greater Petrosal = decreased lacrimation
3. Nerve to Stapedius = hyperacusis
4. Chorda tympani = loss of taste and salivation
5. Posterior digastric
116
Three Ossicles
1. Malleus - chorda tympani nerve crosses over the neck of the malleus
2. Incus - middle bone, part of the incudo-mallear joint
3. Stapes - stirrup-shaped, articulates with the fenestra vestibuli
117
Otosclerosis
Ossification or scarring of the small ossicular joints that prevents the transmission of sound from the tympanic membrane tot he fenestra vestibuli
Tests for bone conduction are normal, but nerve conduction is reduced - hearing is impaired
118
Two Muscles of the Middle Ear Cavity
Tensor tympani and stapedius muscle
119
Tensor Tympani Muscle
Location: in the semicanal of the auditory tube
Innervation: branch of mandibular nerve of CN 5
Action: tightens the tympanic membrane and attenuates its vibrations
120
Stapedius Muscle
Location: in the pyramid on the posterior wall of the middle ear cavity
Innervation: facial nerve
Action: pulls the stapes out of the fenestra vestibuli (protective mechanism for loud sound)
121
Arteriosclerosis of the Labyrinthine Artery
Symptoms: vertigo, nausea, inner ear abnormalities
122
Functions of the Inner Ear
1. Cochlear receptors hearing
2. Receptors in semicircular ducts - detect angular acceleration
3. Receptors in sacculus and utricle - detect linear acceleration
123
Two Labyrinth Layers
Osseous Labyrinth: dense, hard bone called the otic capsule, surrounds membranous layer and encloses the perilymphatic space filled with perilymph
Membranous Labyrinth: consists of membranous ducts, tubes, and sacs which are filled with endolymph and suspended within the osseous labyrinth
124
Semicircular Canals
Three pairs of semicircular canals (3 on each side)
125
Vestibule of the Ear
Houses the utricle in the elliptical cavity and saccule in the spherical cavity
126
Utricle
Communicates with all five semicircular ducts and contains a receptor organ, called the macula utricle which detects linear acceleration
127
Saccule
Connected directly to the cochlear duct by the ductus reuniens
Receptor organ is called the macula saccule which detects low frequency vibrations
128
Cochlea
Helical-shaped bony tube containing:
- promontory: basal turn forms this eminence in the middle ear cavity
- modiolus: bony core of the cochlea where the cochlear nerve passes through
- spiral lamina: projects from modiolus like threads of a screw attached at the cochlear duct
129
Cochlear Duct
Blind-ending, wedge-shaped membranous tube which is continuous with the saccule
The duct is coiled and turns into the apex of the cochlea
130
Organ of Corti (spiral organ)
The cochlear duct contains this organ located along the entire length of the basilar membranes
Contains hearing receptors and tiny blood vessels called stria vascularis
131
Prolonged Exposure to Sound
Excessive amounts of noise may lead to partial destruction of the organ of Corti
Ischemic necrosis might be one of the mechanisms
132
Contents of the Anterior/Posterior Tongue
Anterior 2/3: intrinsic muscles innervated by CN9
Posterior 1/3: lymphatic tissue + lingual tonsils
133
Types of Lingual Papillae
1. Filiform papillae - most abundant, grabs food
2. Fungiform papillae - registers taste
3. Circumvallate papillae - has surrounding trench, found on sulcus terminalis
4. Foliate papillae - tastebuds on lateral walls, serous glands
134
Geographic Tongue
Oral manifestation of psoriasis - see areas of erythema/atrophy in between areas of white/hyperkeratotic regions
135
Vitamin B12 Deficiency
B12 needs intrinsic factor - lacking after a gastric bypass
Can see this deficiency on the tongue = yellow streaks
136
Taste Receptor Cells
Found in papillae (fungiform, circumvallate, foliate)
Also in the soft palate, posterior pharynx, and epiglottis (innervated by the vagus nerve)
137
Where are taste buds NOT found?
In the filiform papillae!
138
Serous Glands (Von Ebner Glands)
Found on the foliate, fungiform, and circumvallate papillae (anywhere there are tastebuds)
Secretes lingual lipase and Von Ebner's gland protein (VEGP) to bind to chemicals in food
139
Pathway of Tastants
Diffuse through the pore and activate GPCRs on taste receptor cells --> leads to an increase in calcium for release of the neurotransmitter
140
Types of Tasters
Nontaster (few fungiform)
Normal taster
Supertaster (high density of fungiform)
141
Locations of Taste Perception
```
Sweet: tip of the tongue
Salty: posterior/lateral
Sweet: anterior 2/3 of dorsum, lateral margins
Bitter: on the back of the tongue
Umami: no specific location
```
142
Salty stimuli utilize this type of channel:
Sodium channel
143
Sour stimuli utilize this type of channel:
Hydrogen ion channel
144
Genetic Control of Bitter Taste
Some people really can't stand bitter tastes (caffeine, morphine, and nicotine)
Defect in hTAS2R38 taste receptor gene
145
This additive in foods for enhacement:
monosodium glutamate (umami taste)
146
Receptor for the flavor of fat:
Protein (CD36) Receptor
147
Most sensory information of taste is actually this type of sensation:
Olfactory, by olfactory mucosa
148
Functions of the Nasal Mucosa
Air hydration, air filtration, and temperature regulation
149
Components of Nasal Cavity
Pseudostratified columnar epithelium with goblet cells
Serous/mucous glands to trap contaminants, extensive vascular plexus = lamina propia
Mast and plasma cells (IgA, IgE, IgG)
150
Olfactory Epithelium Components
*only found in the roof of the nasal cavity*
Olfactory cells, supporting cells, and basal cells
151
Olfactory Cells
Bipolar sensory neurons with a proximal process that extends basally to form a bundle of nerves (fila olfactoria)
These can be regenerated!
152
Odorant Receptor
Each receptor expresses one OR gene
153
Glands of Bowman
Secretes fluid that contains odorant-binding protein (OBP) to dissolve odoriferous substances and carries them to receptors
Contains lysozyme and IgA for protection
154
Temporary or permanent damage to any part of the olfactory system can lead to:
Anosmia
155
Kallman Syndrome
Characterized by anosmia (lack of neurons in the brain), small genitalia, and sterility (due to lack of GnRH)
May be due to a defective gene, KAL-1
156
There are NO lymphatics in this part of the head:
Orbit or eyeball!
157
Medial and Lateral Canthi
Corners of the eye
158
Sty
Caused by ciliary glands becoming infected
159
Levator Palpebrae Superiorus Muscle (LPS)
Responsible for lifting the eyelid, innervated by oculomotor
**if oculomotor is cut, there will be COMPLETE PTOSIS**
160
Paralysis of Tarsal Muscle (of Muller)
Characteristic feature of Horner's Syndrome providing partial ptosis and miosis
161
Lacrimal Gland
Mostly rests on top of the lateral rectus muscle, oval-shaped, and secretes tears to keep the eyes moist
Innervation: (parasympathetic) superior salivatory nucleus --> CN7 --> greater superficial petrosal nerve --> vidian nerve --> sphenopalatine ganglion --> zygomatic --> lacrimal
(sympathetic) internal carotid plexus --> deep petrosal --> vidian nerve
162
Bony Orbit Margins
Supraorbital margin: frontal bone
Medial margin: maxilla, lacrimal, and frontal bones
Lateral margin: zygomatic bone
Infraorbital margin: zygomatic and maxilla bones
163
Hematoma or Edema in the Orbit
Usually appear in the medial margin in a characteristic sickle shape
164
What goes through the optic canal?
Optic nerve and ophthalmic artery
165
Traumatic Optic Neuropathy
The intracanalicular portion of the optic nerve is the most frequent site due to its vulnerable blood supply (ophthalmic artery)
Results in immediate or slow progressive loss of vision in the affected eye
166
What goes through the superior orbital fissure?
CN 3, 4, 5 (V1), and 6 and the ophthalmic vein
167
Blow Out Fractures
Happen on the floor of the orbit, typically due to a trauma to the front of the eyeball or a depressed fracture of the zygomatic bone
Can cause herniation into the maxillary sinus
168
Le Forte Type 1
Transverse fracture of the maxilla just above the teeth (unilateral)
169
Le Forte Type 2
Pyramid-shaped fracture of the maxilla usually involving part of the medial margin of one of the orbits (unilateral)
170
Le Forte Type 3
Extensive fracture involving many facial bones and both orbits (panda bear appearance) - bilateral
171
Lesion of Superior Division of Oculomotor Nerve
Paralysis of LPS and Superior Rectus = complete ptosis, inability to abduct and elevate the affected eye
172
Lesion of Inferior Division of Oculomotor Nerve
Paralysis of medial rectus, inferior rectus, and inferior oblique = inability to adduct, abduct/depress, and adduct/elevate the eye
173
Overall Oculomotor Lesion
Complete ptosis and eye down and out (external strabismus)
174
Lesion of Trochlear Nerve
Paralysis of superior oblique = inability to adduct and depress the eye
Patient will tilt head away from the affected eye
175
Lesion of Abducens Nerve
Paralysis of lateral rectus = inability to abduct
Causes diplopia (double vision)
**Increased intracranial pressure may compress abducens**
176
Ophthalmic Division (V1) of CN 5
Remember this by N F L
N: nasociliary nerve = main sensory to the eyeball (GSA) and gives off five branches
- need to know: long ciliary, posterior ethmoidal (supplies the sinuses), and infratrochlear (supplies medial canthus)
F: frontal nerve = passes through the superior orbital fissure to branch as supraorbital and supratrochlear nerves
L: lacrimal nerve = entirely GSA and courses just above the lateral rectus, terminates in the lacrimal gland
177
Stimulus Pathway of Direct and Consensual Corneal Reflex
Stimulus: lightly touching cornea with cotton swab
Afferent: nasociliary, esp long ciliary nerves
Efferent: facial nerve
Response: blinking (both eyes)
* *in by 5, out by 7**
* *this can be lost after endoscopic forehead lift**
178
Innervation to the Eye
Parasympathetic: Edinger-Westphal nucleus --> CN 3 --> ciliary ganglion --> sphincter pupillae and ciliary muscle
**response causes constriction of pupil and thickening of lens = accomodation**
179
Ophthalmic Artery
**Chief artery of the orbit and the first branch of ICA**
Has 12 branches; most important are the central retinal artery and posterior ciliary artery
Also includes: lacrimal (to the gland), supraorbital (upper eyelid and scalp), anterior and posterior ethmoidal (nasal cavity and sinuses), and short ciliary arteries
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Terminal Branches of Ophthalmic Artery
Supratrochlear and Dorsal Nasal Arteries
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Central Retinal Artery
Contributes the main blood supply to the retina - supplies the four quadrants of the retina through the upper and lower temporal branches, and upper and lower nasal branches = end arteries
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The central retinal artery and posterior ciliary artery form:
An incomplete circle of Zinn-Haller around the iris and deep pericorneal plexus
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Ophthalmic Veins
Superior ophthalmic vein and the central vein of the retina drain into the cavernous sinus
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Action of Ciliary Muscles
When stimulated, they decrease the tension on the ciliary fibers and thicken the lens
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Site of production of aqueous humor:
Ciliary Processes
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The pupil divides the space between the lens and cornea into:
Anterior and posterior chambers with the iris in the middle of the two
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Sphincter Pupillae Muscle
When contracted, they decrease the diameter of the pupil (postganglionic parasympathetic fibers from ciliary ganglion)
**This is paralyzed by atropine to dilate pupil**
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Dilator Pupillae Muscle
When contracted, increase the diameter of the pupil (postganglionic sympathetic fibers by the SNS branch to the ciliary ganglion)
Horner's Syndrome characterized by paralysis of this muscle with the tarsal muscle
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Causes of Horner's Syndrome
Mass effect: pancoast tumor
Aortic aneurysm, carotid artery aneurysm
Idiopathic/congential
**will see anhidrosis - patient's face half flushed**
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Lens of the Eye
Suspended by ciliary zonule fibers and focuses images onto the fovea of retina
Opacities that form = cataracts
Surgical procedure to place artificial lens
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Direct vs Consensual Light Reflex
Direct: **in by 2, out by 3**, ipsilateral pupil constriction
Consensual: contralateral pupil constriction
Direct reflexes will travel from the ipsilateral retina --> pretectum and then enters the POSTERIOR COMMISSURE where it will cross over to EWN and provide consensual reflexes in contralateral eye
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Lesion to the Posterior Commissure
Will still have direct reflexes, but NO consensual reflexes
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Other causes of pupillary constriction:
Parasympathetic response, opioids
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Pupillary Dilation Response
Stimulus: decreased light
Signal travels from retina --> pretectum --> reticular formation --> preganglionic sympathetics (ILCC at T1) --> SCG --> pupillary dilator muscle
Response: pupillary dilation
**can also be a sympathetic response**
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Triad of Accommodation
Convergence of gaze due to bilateral contraction of medial recti muscles
Pupillary constriction from sphincter pupillae muscles
Thickening of lens due to relaxation of ciliary fibers
**helps view objects coming towards you, cortically-mediated**
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Argyll-Robertson Pupil
Result of syphilis infection = pupils are unreactive to light but have accommodation
*prostitute's pupil*
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Holmes-Adie Pupil
Tonic pupil, benign condition due to lesion of ciliary ganglion; more common in young females
Pupil is unreactive to light and very slowly reacts to convergence (slow accommodation)
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Hyphema
Vessel: Arterial circle of iris
Presence of blood in the anterior chamber of the eyeball due to trauma = serious medical emergency
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Subconjunctival Hemorrhage
Vessel: deep pericorneal plexus
Bleeding is restricted to the subconjunctival tissue or bulbar fascia (see blood in the white of the eye)
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Conjunctivitis
Vessel: superficial pericorneal plexus
Brick-red inflammation of conjunctiva; more noticeable at the fornices
When touched, the redness does not fade and vessels are moveable
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Photoreceptors in the DARK
Sodium channels are OPEN and the cell is DEPOLARIZED
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Photoreceptors in the LIGHT
Sodium channels are CLOSED and the cell is HYPERPOLARIZED
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Respiratory Quotient
Cells in the outer segment require a lot of oxygen and have the highest respiratory quotient in the body
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Retinoid Cycle
1. Starts in the rod cell: converts 11-cis to 11-trans, exports all-trans-retinol with iBRP
2. Moves to the retinal pigmented epithelium: esterification by LRAT, conversion to 11-cis by RPE65
3. Back to the rod cell: uptake of 11-cis, covalent attachment to Schiff base to form Rhodopsin
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Process of Action and Recovery of Photoreceptors
1. Dissociation of signal molecule from receptor
2. Phosphorylation of the C-terminus
3. Arrested by b-arrestin
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Activation and Recovery (chemical)
Activation: decrease in cGMP
Recovery: increase in cGMP
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Vitamin A Deficiency
Causes night blindness and xerophthalmia (dryness of the cornea, inflamed conjunctiva, ridge formation)
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Macular Degeneration
Macula: yellow area of the retina that contains the fovea (most cones) and responsible for high visual acuity
Perfect storm for MD: high respiratory quotient, high lipid content, and UV rays
Macular carotenoids (xanthophylls): found in green, leafy vegetables that can prevent MD; cigarettes/nicotine thought to be the top cause of MD
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Retinitis Pigmentosa
Damage to the back of the eye - degenerative, inherited disease that slowly kills off rod photoreceptors
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Defect in Rhodopsin
Inability for rhodopsin to be the correct shape - causes a degeneration of LRAT and RPE65
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Opsin Proteins and Genes
Rod opsin: chromosome 3
Blue opsin: chromosome 7
Red opsin: chromosome X
Green opsin: chromosome X
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Recombination Between Genes
Leaves one set without a color gene and another with multiple
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Recombination Within Genes
Creates a greenlike/redlike hybrid
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Color Blindness
Typically due to nonhomologous recombination (losing the green opsin gene means they can't see green)
Only takes a small change in AAs of rhodopsin receptor to make a difference in absorbance
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Tetrochromad
Possibility of a hybrid that can supposedly see more colors
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Amplification of Light
1. Photon puts the cell into hyperpolarization
2. All proteins are activated
3. Sodium channels close
4. Rod cell membrane is hyperpolarized by 1mV
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Three Tunic Layers
Outer (sclera and cornea)
Middle (uvea, choroid, iris, ciliary body)
Inner (retina)
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Layers of the Cornea
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Corneal epithelium
Bowman's layer (hemidesmosomes)
Stroma
Descemet's membrane
Corneal epithelium
```
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Point between cornea and sclera:
Limbus
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What part of the eye is responsible for focus?
Zonule fibers adjusting the lens
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Detachment of the Retina
Separation of the two layers of the retina caused by trauma, vascular disease, metabolic disorders, and aging
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Anterior and Posterior Chambers
Anterior: between the cornea and iris
Posterior: between the iris and lens
Both contain aqueous humor (fluid-like)
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Canal of Schlemm
Goes all the way around the iris but fluid only percolates into the trabecular meshwork
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Glaucoma
Obstruction of aqueous humor (usually at the Canal of Schlemm) causes increase in intraocular pressure
Produces pain and nausea
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Cataracts
Happens when the major proteins in the lens become insoluble (also happens with glucose)
Results from aging and diabetes
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Red Eye
Subconjunctival hemorrhage and conjunctivitis
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Footplate of the Stapes
Responsible for vibrations on the oval window which tells the brain there are sound waves coming through and how strong/frequent they are
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Olfactory Receptors are GPCRs, what is the sequence of events once activated?
Create cAMP and open the ion channel for sodium and calcium influx
**if the odorant persists for a while, sensitivity of the channel is reduced and ions reduced**
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How do we change the perceived smell?
By changing the odorant concentration (think of the citrus/grapefruit example)
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Pathway of the Olfactory Neurons
Neurons --> glomeruli --> post-synaptic cells which include mitral and tufted cells as well as periglomerular cells
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What do periglomerular cells secrete?
GABA (inhibitory)
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How are other smells prevented?
The odorant producing the stronger stimulation will suppress the input from other glomeruli
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Entorhinal Cortex
Projects to the hippocampus for memory formation
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Piriform Cortex
Projects to lateral hypothalamus, important for appetite
Projects to medial hypothalamus, identifies flavor of food
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Umami stimuli activate:
Metabotropic receptor activated by glutamate
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If the object is far away....
Less refraction is required to bend the light
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If the object is nearby...
More refraction is required to bend the light
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First site where refraction occurs (and most of it too)
Cornea
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What structure in the eye allows for variable refraction?
Lens
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Near response from the ciliary muscles, suspensory ligaments, and lens: (accommodation reaction)
Ciliary muscles: contracts
Suspensory ligament: becomes slack
Lens: thicker and curved
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Far response from the ciliary muscles, suspensory ligaments, and lens:
Ciliary muscles: relaxes
Suspensory ligament: becomes taut
Lens: decreased curvature
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Refractive Power at Life Stages (diopters)
Kids: 20 diopters
Young adults: 10 diopters
Elderly: 1 diopter
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Three Parts of the Near Vision Response
Contraction of ciliary muscles
Convergence of eyes to the point of focus
Constriction of the pupil
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Visual inputs are provided by these structures:
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Lateral geniculate body
Primary visual cortex (V1)
V2
V4
Inferior temporal cortex
Parietal/frontal cortex
```
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Functions of the Lateral Geniculate Body
Control motion of the eye
Control focusing
Identify major elements in our vision
Identify motion
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Parts of the Primary Visual Cortex
6 Layers that control muscle response and tells the eyes what to focus on
Columns that have various jobs but related to columns nearby
- this is split into upper/lower quadrant of macula (cones, larger) and upper/lower quadrants of retina (rods)
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Major Job of V2 in Vision
Identify disparities in visual images presented by both eyes for depth perception
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Major Job of V4
Complete processing of color inputs
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Concentration of Perilymph (in scala vestibuli and tympani)
Most similar to CSF: high Na, low K
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Concentration of Endolymph (scala media)
High in K, low in Na
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Impedance Matching
Sound waves go from air to liquid (done by ossicles)
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High Frequency (short wavelength) sounds maximal where?
Closest to the oval window
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Low Frequency (long wavelengths) is maximal where?
Farthest away from oval window, near the helicotrema
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Actions of the Cochlear Nuclei
Ventral: time and pitch
Dorsal: localizes the sound
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Actions of the Superior Olives
Medial: maps intraaural time differences
Lateral: maps intraaural intensity
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Inferior Colliculus vs Superior Colliculus
Inferior: suppresses echoes
Superior: adds vertical height
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Primary Auditory Cortex Areas
Rostral areas: low frequency sounds
| Caudal areas: high frequency sounds
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Anterior Semicircular Canal
Maximal motion: falling forward
Muscles activated: superior rectus activated, inferior rectus inhibited
Eye movement: UP
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Horizontal Semicircular Canal
Maximal motion: turning motion
Muscles activated:
- ipsilateral: MR activated, LR inhibited
- contralateral: LR activated, MR inhibited
Eye movement: LEFT AND RIGHT
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Posterior Semicircular Canal
Maximal motion: falling backward
Muscles activated: superior oblique activated
Eye movement: DOWN
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Utricle Motion
Horizontal motion (walking)
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Saccule Motion
Vertical motion (jumping)
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Action by cortical and cerebellar involvement in reflexes is:
To suppress the reflex to allow for voluntary motion
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What part of the brain controls the set point temperature?
Hypothalamus
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Difference between a feedback and feed-forward system?
Feedback: most systems in the body are a negative feedback system
Feed-forward: prevents changes in the controlled variable; happens in the hypothalamus
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Definition of Thermoreceptors
Neurons which change their firing rate in response to changes in local temperature
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Warm Sensitive Thermoreceptors
4 channels: TRP-V1 through 4
Can be activated by vanilloid (found in capsaicin)
Allows Na and Ca influx
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Cold Sensitive Thermoreceptors
2 channels: TRPM8 and TRPA2
Activated by menthol
Allows Na and Ca influx
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Thermoreceptors are found in:
Skin, viscera, and the brain
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Cutaneous Thermoreceptors
These are bimodal = touch and temp sensitive
10x as many cold sensitive than warm
Tells us environmental conditions
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Gut Thermoreceptors
Sense core temps and threats to maintenance
Food ingested may change body temperature
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Central Thermoreceptors
Location: pre-optic and superoptic region of the hypothalamus
3x as many warm sensitive as cold
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Anterior Division of Hypothalamus
HEAT LOSS BEHAVIORS - YOU'RE TOO HOT
Mechanisms: evaporative heat loss, convection, conduction, and radiation
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Posterior Division of the Hypothalamus
HEAT PRODUCTION BEHAVIOR - YOU'RE TOO COLD
Mechanisms: can either be ANS or hormonal, muscular activity, and non-shivering thermogenesis
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Process of Evaporative Heat Loss
1. Insensible (respiratory) - we can't control this
2. Sweating (controlled) - innervated by sympathetics (cholinergic)
- can either have a low flow rate (concentrated) or a high flow rate (mostly water, happens when very hot)
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Convection vs Conduction vs Radiation
Convection: heat transferred through air molecules
Conduction: heat transferred through touching objects
Radiation: heat transferred through non-touching objects
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Types of Muscular Activity
Shivering: dorsomedial posterior hypothalamus, increased motor neuron excitation
Increase voluntary activity via cortex: jumping and running
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Types of Non-shivering Thermogenesis
Hormonal influence: thyroxin and epinephrine increases heat production, stimulated by cold
Increase food intake: increase metabolism
Brown adipose tissue: mostly in babies, requires exposure to cold and uncoupling protein
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Challenges for Hypothalamus to Overcome
Anaerobic and aerobic metabolism that produce heat
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Environmental vs Body Temperature
Core temperature is the most stable/constant - well regulated
Oral temperature very stable too
Average skin slightly less stable
Hands and feet are very variable
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With sleep, temperature will:
DROP - due to circadian rhythm, whether at night or during the day, set point temperature decreases
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With exercise, temperature will:
INCREASE - increased heat production, set point increases
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Definition of a Fever
CONTROLLED increase in body temperature driven by a set point increase
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Stages of a Fever
1. Secretion of endotoxins
2. Increase heat production and decrease heat loss
3. Body creates new "comfort" temperature
4. Bug is vanquished - no more endotoxins
5. Body temp > set point
6. Body temp = set point
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Definition of Hyper and Hypothermia
UNCONTROLLED - set point remains normal but environmental stresses exceeds body's ability to regulate temperature
