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*RACS ENT Fellowship > Anatomy & Branchial Arches > Flashcards

Anatomy & Branchial Arches Flashcards

1
Q

BRANCHIAL ARCHES 
Definitions - epidemiology

A

Defintion A congenital anomaly of the neck due to disturbances in the complex development of the branchial apparatus of the foetus

Btwn weeks 4-7 of development

Epidemiology 17% paediatric neck masses

Definitions:

Arch- mesoderm

Cleft- ectoderm

Pouch- endoderm

Branchial membrane- cleft and pouch in contact. Only preserved in 1st arch (i.e. TM)

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2
Q

BRANCHIAL ARCHES 
 Theories

A

Theories of development:

  1. Branchial remnant
  2. Salivary gland inclusion in a lymph node
  3. Squamous metaplasia of a LN
  4. Thymopharyngeal theory (persistent connection between thymus and its pharyngeal origin)
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3
Q

BRANCHIAL ARCHES 

 Embryology

A

Embryology:

4/40- 4 arches arise at lateral pharynx and grow forward to meet in midline - V and VI are rudimentary

5/40- development of cervical sinus (2nd arch grows over 2, 3, 4, clefts)

6/40- 6 Hillocks of His develop to form pinna (1, 2, 3- 1st arch, 4, 5, 6- 2nd arch)

7/40- skin smooth over anterior neck

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4
Q

BRANCHIAL ARCHES 

 Pathology

A

Pathology:

Thin-walled cystic structures. 90% contain squamous epithelial lining. 10% contain respiratory epithelium (ciliated columnar)

Nodular or diffuse lymphoid infiltrate often with germinal centres

Cyst fluid contains cholesterol crystals

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5
Q

BRANCHIAL ARCHES 

 Syndromes associated

A

Syndromic associations:

  1. Treacher-Collins Syndrome
  2. Goldenhar
  3. Di George
  4. Pierre-Robin Sequence
  5. Branchio-Oto-Renal
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6
Q

1st BRANCHIAL ARCH CYSTS Work type 1

A

Work Type 1:

Ectodermal - Doesn’t communicate with EAC - Presents as mass around lower ear - Runs parallel to EAC. Involves parotid tissue, superior to VII

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7
Q

1st BRANCHIAL ARCH CYSTS Work Type 2

A

Work Type 2:

Ectoderm and mesoderm - Cartilage + skin adnexa (hair follicles, sebaceous glands, sweat glands) - Present as mass around ear, AoM / SCM / otorrhoea - Duplication anomaly of membranous and cartilagenous EAC - More intimately assoc with VII (may run through main trunk) - Myringeal band- floor of hypotympanum to umbo - Pathognomonic - MRI will demonstrate its tract - High recurrence rate - ave 2.4 procedures/pt

8-10% of all branchial arch anomalies

Cysts twice as common as sinuses/fistulae

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8
Q

1st BRANCHIAL ARCH CYSTS Clinical & radiological findings Recurrence rate

% of all BA anoms

A
  • Myringeal band- floor of hypotympanum to umbo
  • Pathognomonic
  • MRI will demonstrate its tract

- High recurrence rate - ave 2.4 procedures/pt

8-10% of all branchial arch anomalies

Cysts twice as common as sinuses/fistulae

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9
Q

2nd ARCH FISTULA TRACT AND CYSTS Classification

A

Classification of 2nd arch cysts:

Type 1- superficial at border of SCM

Type 2- between SCM and IJV

Type 3- in the carotid bifurcation

Type 4- in the pharyngeal wall

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10
Q

2nd ARCH FISTULA TRACT AND CYSTS Describe



A

External: lower 1/3 of neck, anterior border SCM

Fistula tract: - caudal to platysma, through deep fascia to carotid sheath - below stylohyoid and above (superficial) IX and XII - between ICA, ECA

Enters pharynx- anterior aspect of posterior faucial pillar

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11
Q

2nd ARCH FISTULA TRACT AND CYSTS Recurrence

A

Recurrence rates in 2nd arch surgery (Mayo clinic, n=208):

  • Prior surgery = 21%
  • Prior infection = 14%
  • No infection/surgery = 3%
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12
Q

3rd ARCH FISTULA TRACT Describe & course

A

Fistula tract:

External: as for 2nd arch fistula - lower 1/3 of neck, anterior border SCM

Course: inferior to CN IX, superior to CN XII, posterior to ICA

Internal: pierces thyrohyoid membrane to open in upper piriform fossa

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13
Q

4th ARCH FISTULA TRACT

Describe & course

A

Fistula tract:

External: as for 2nd/3rd arch fistulae - lower 1/3 of neck, anterior border SCM

Course: deep to platysma, loops over CN XII, turns caudally in carotid sheath, loops around 4th arch artery (R SCA, L arch of aorta)

Internal: pierces cricothyroid membrane, opens to piriform apex

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14
Q

PARAPHARYNGEAL SPACE 

Boundaries

A

An inverted pyramid shape

Potential space lateral to upper pharynx, filled with fat and areolar tissue

Boundaries

Superior (base) - base of skull (temporal/sphenoid) Inferior (apex) - junction of digastric tendon with lesser horn of hyoid

Anterior - Pterygomandibular raphe and medial pterygoid fascia

Posterior - Pre-vertebral fascia

Medial - Buccopharyngeal fascia overlying sup constrictor and pharyngobasilar fascia. Fascia from TVP to medial pterygoid

Lateral - Fascia overlying medial pterygoid, mandibular ramus, PBD and deep lobe of parotid 


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15
Q

PARAPHARYNGEAL SPACE 
 Divisions

A

Division is by the Styloid process tensor-vascular-styloid fascia

  1. Prestyloid - Fat, deep lobe parotid, LNs, Styloglossus, Stylopharyngeus, V3 branches, TVP, LVP, IMA, asc palatine a, asc pharyngeal a
  2. Post-styloid - Cartoid sheath (ICA, IJV, X), SNS trunk, IX, XI, XII, IMA, paraganglionic tissue
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16
Q

PARAPHARYNGEAL SPACE 

 Communcations xxxx x

A

Communications

Medial - peritonsillar space

Anterolateral - Masticator space

Posteromedial - Retropharyngeal space

Inferomedial - Submandibular space

Lateral - Parotid space

Posterior - Carotid sheath contents

Superior - ITF

Pathology: 80% benign, 20% malignant (mostly salivary)

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17
Q

TEMPORAL FOSSA Boundries

A

Boundaries:

Superiorly - by the superior temporal line.

Inferiorly - zygomatic arch (arbitrary designation)

Floor - bones of the lateral aspect of the skull, including a portion of the frontal, GW sphenoid, the temporal, and the parietal bones

Separated inferior from infratemporal fossa by the infratemporal crest of the greater wing of sphenoid

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18
Q

TEMPORAL FOSSA Contents

A

Contents: Temporalis muscle - attaches superiorly to inferior temporal line

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19
Q

TEMPORAL FOSSA Superior Temporal Line

A

Superior temporal line:

Anteriorly - Zygomatic process of the frontal bone

Arches posteriorly over the parietal bone before descending to the temporal bone, where it blends into the zygomatic process

Attachment of temporalis fascia

Vertical groove on squamous temporal bone = superficial temporal vessels

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20
Q

INFRATEMPORAL FOSSA 
Boundaries

A

A space lying beneath the base of skull between side wall of pharynx and ramus of mandible

Boundaries

Superior - IT surface of greater wing of sphenoid, Squamous temporal bone - Continous with temporal fossa laterally (infratemporal crest marks this transition)

Inferior - Opens into the neck

Anterior - Posterior surface of maxilla and IOF

Posterior - Upper carotid sheath

Medial - Lateral surface of lateral pterygoid plate, TVP/LVP/superior constrictor, pterygomaxillary fissure (connects to PPF)

Lateral - Ramus of mandible and its coronoid process

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21
Q

INFRATEMPORAL FOSSA 
 Contents xxxx

A

Contents: Medial pterygoid Lateral pterygoid Insertion of temporalis into coronoid process Internal maxillary artery Pterygoid venous plexus V3 and branches (+ otic ganglion, chorda tympani) PSAN (of V2)

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22
Q

MUSCLES OF MASTICATION xxxxxx x

A

1. Medial pterygoid

  • Origin - Deep head: Medial surface LPP, fossa between MPP/LPP - Superficial head: maxillary tuberosity and pyramidal process of palatine bone
  • Insertion - Angle of mandible (broad insertion)

2. Lateral pterygoid

- Origin - Upper head - Infratemporal surface of skull (GW sphenoid) - Lower head - Lateral surface of LPP - Insertion - Pterygoid fovea (beneath medial end of mandibular head) - Articular disc and capsule of TMJ

3. Temporalis - Origin - Temporal fossa

  • Insertion - Coronoid process and down ramus to buccinator insertion

4. Masseter

  • Origin - Zygomatic arch
  • Insertion - 3 heads of masseter fuse anteriorly - Posteriorly they diverge from one another - Superficial - broad attachment - body, angle, ramus - Intermediate - ramus - Deep - ramus - Between the heads: sup / intermed = masseteric artery, intermed / deep = masseteric nerve
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23
Q

PTERYGOPALATINE FOSSA Def & boundries

A

Lies between back of maxilla and pterygoid process of sphenoid

Boundaries:

  1. Posterior - sphenoid bone - a. root of pterygoid process (incl Vidian Canal), b. greater wing (incl Foramen Rotundum)
  2. Medial - palatine bone (incl notch for SP foramen)
  3. Anterior - posterior wall of maxilla - leads to IOF
  4. Roof - a. body of sphenoid, b. orbital process of palatine bone
  5. Lateral - pterygomaxillary fissure (leads to ITF)
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24
Q

PTERYGOPALATINE FOSSA Contents

A

Contents:

1. V2 - Meningeal branch (to MCF) - Zygomatic Nerve (arises in PPF and runs to IOF above V2), takes the secretomotor fibres from the ganglion (pass to lacrimal gland via Lacrimal branch of V1) - Post Sup Alveolar N - Exits via Pterygomaxillary Fissure to posterior surface of maxilla - V2 exits through IOF to become ION - Ganglionic branch

2. Pterygopalatine Ganglion - Connected to V2 by short trunk (inf/med to V2) - Only cell bodies are PSNS (SNS and sensory fibres ‘relay station’) - Autonomic root is Vidian N (PSNS- GSPN, SNS- ICA plexus via DPN) - Fibres arise in Superior Salivary Nucleus 3. Maxillary Artery 5 branches accompany the 5 nerves of the PPG - Vessels lie in front of nerves

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25
Q

PTERYGOPALATINE Ganglion 

Branches

A

Branches of the Pterygopalatine Ganglion:

1. Nasopalatine N - SP foramen - Septum + incisive gum of hard palate (descends down incisive foramen)

2. Lat Post Sup Nasal Ns - SP foramen - Postersup quadrant of LNW

3. Greater Palatine N - GP foramen/canal (junction of maxilla and palatine bone) - Mucosa of hard palate - Nasal branches - posteroinf quadrant LNW + med wall max sinus

  1. Lesser Palatine Ns - Lesser palatine foramina (behind GPN) - Soft palate and tonsil mucosa
  2. Pharyngeal N - Palatovaginal canal - Nasopharynx mucous membrane
  3. Orbital branches - IOF - Orbital periosteum, orbitalis muscle - Sphenoid/ethmoid sinuses
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26
Q

TONGUE xxxx

A

Mass of skeletal muscle with midline fibrous septum covered by mucous membrane - Keratinising stratified squamous epithelium Parts of the tongue: - Dorsum, tip, ventral surface, base (BOT is oropharynx not oral cavity)

Papillae:

  1. Filiform- velvety appearance
  2. Fungiform- discrete pink pinheads (bears the taste buds)
  3. Circumvallate- 12, form a V in front of sulcus terminalis (marks division of oral cavity and oropharynx

Folds: Median glossoepiglottic, lateral glossoepiglottic

Muscles:

  1. Intrinsic x4 shape no bony attachments - longitudinal (sup/inf), vertical, transverse
  2. Extrinsic x 4 position - Genioglossus - bulk of tongue. Genial tub to mucous memb + hyoid (i.e. geniohyoglossus) - Hyoglossus - length of greater horn/body of hyoid (free ant + post borders) - Styloglossus - low/ant styloid to interdig with hyoglossus - Palatoglossus - undersurface of palate to interdig with styloglossus
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27
Q

TONGUE Parts

A

Mass of skeletal muscle with midline fibrous septum covered by mucous membrane - Keratinising stratified squamous epithelium Parts of the tongue:

  • Dorsum, tip, ventral surface, base (BOT is oropharynx not oral cavity)
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28
Q

TONGUE Papillae

A

Papillae:

  1. Filiform- velvety appearance
  2. Fungiform- discrete pink pinheads (bears the taste buds)
  3. Circumvallate- 12, form a V in front of sulcus terminalis (marks division of oral cavity and oropharynx
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29
Q

TONGUE Folds & Muscles

A

Folds:

Median glossoepiglottic, lateral glossoepiglottic

Muscles:

  1. Intrinsic x4 shape no bony attachments - longitudinal (sup/inf), vertical, transverse
  2. Extrinsic x 4 position - Genioglossus - bulk of tongue. Genial tub to mucous memb + hyoid (i.e. geniohyoglossus) - Hyoglossus - length of greater horn/body of hyoid (free ant + post borders) - Styloglossus - low/ant styloid to interdig with hyoglossus - Palatoglossus - undersurface of palate to interdig with styloglossus
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30
Q

TONGUE Blood & nerve supply

A

Blood supply: Lingual A. - above greater horn of hyoid - Dorsal lingual branches to posterior tongue Asc Pharyngeal, tonsil branches of Facial- small contributions Lingual v. - tributaries run with Lingual a. Deep Lingual v. (visible in FOM) + sublingual v. — vena comitants of XII

Nerve supply: Anterior 2/3 - sensation- Lingual N., Taste- chorda tympani Posterior 1/3 - IX (sensation + taste), X (internal branch of SLN- ant valleculla) Motor - all CN XII except palatoglossus (pharyngeal plexus)

** taste travels to nucleus tractus solitarius

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31
Q

TONGUE Embryology

A

Embryology:

Appears during Week 4 - as the tuberculum impar.

2 lateral swellings appear either side of the tuberculum —> fuse to form the midline fibrous septum (Arch I)

Base of tongue is formed from the hypobranchial eminence (Arch III). This joins with the lateral swellings at the sulcus terminalis to form the tongue

Tongue muscles derived from suboccipital myotomes (ie not supplied by branchial arch nerves - XII instead)

Migrate forward into the sac of mucous membrane derived from arches I, III, IV

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32
Q

PHARYNX Def

Layers

A

BOS to C6 (12cm), open anteriorly

Divided to Naso-, Oro-, Hypo- - Free edge of soft palate - Tip of epiglottis (level of hyoid)

Layers of Pharynx

  1. Mucosa
  2. Submucosa- thickened superiorly as the Pharyngobasilar Fascia
  3. Muscle - 3 constrictors, 3 other
  4. Buccopharyngeal Fascia (thickening of the epimysium of the muscle layer)
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33
Q

PHARYNX Attachments

A

Attachments of the Pharyngobasilar Fascia

  • Pharyngeal tubercle (occipital bone) - Laterally across longus colli, anterior to carotid canal/foramen lacerum, drapes off ET - Medial Pterygoid plate down to hamulus
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34
Q

PHARYNX Constrictors

A

Constrictor muscles insert to the pharyngeal raphe (midline posteriorly) and fan out from there to the following attachments:

  • Superior - Hamulus, pterygomandibular raphe, mandible
  • Middle - Angle between Stylohyoid (at lesser horn) and hyoid bone
  • Inferior - 2 parts: - Thyropharyngeus - Oblique line of thyroid and fibres spanning CT muscle - Cricopharyngeus - Cricoid cartilage (full ring of muscle) - Killian’s dehiscence between TP and CP
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35
Q

PHARYNX Structures entering & relationship to constrictors

A

Structures enter pharynx from outside:

Above SC - Eustachian tube

Between SC/MC - IX, Lingual N, Stylopharyngeus

Between MC/IC - IBSLN, SL vessels (thyrohyoid membrane)

Under IC - RLN

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36
Q

PHARYNX Innervation

A

Innervation - All pharyngeal plexus (IX, X, SNS fibres) - SNS fibres are vasoconstrictor - Arise in Nucleus Ambiguus - Except Stylopharyngeus - IX

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37
Q

TONSIL ANATOMY Def and parts

A

Paired lymphoid aggregates in the lateral oropharyngeal wall forming part of Waldeyer’s Ring

  • Specialized lymphoid aggregates with external lining of stratified squamous epithelium

2 borders - Anterior - Palatoglossal arch - Posterior - Palatopharyngeal arch

2 poles - Upper - Soft palate - Lower - Tongue base

2 surfaces - Medial - Pharyngeal mucosa (stratified squamous epithelium) with crypts (up to 20 in number) - Lateral - Covered by capsule ( a thickening of the submucosa/extension of PB fascia) - Connective tissue septae extend to tonsil from capsule (not easily separated)

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38
Q

TONSIL ANATOMY Relations

A

Relations of the tonsil

  • SC
  • Stylopharyngeus, Styloglossus, Stylohyoid lig, Styloid process
  • ICA (2cm posterolateral to tonsil bed)
  • IX
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39
Q

TONSIL ANATOMY Blood sup

A

Blood supply:

5 arterial sources, tonsillar branches of

  1. Ascending pharyngeal a.
  2. Lesser palatine a. (3rd part IMA)
  3. Ascending palatine a. (branch of Facial a.)
  4. Facial a.
  5. Lingual a.

Venous drainage

  1. Venous plexus forms around capsule then drain to tonsil branch of Lingual v.
  2. Accessory Tonsil v. (drains to pharyngeal plexus)
  3. External palatine v. (superior pole)
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40
Q

TONSIL ANATOMY Embrology

A

Embryology:

Begins 12 weeks

Derived from 2nd pharyngeal pouch endoderm

Lymphocytes migrate into the area (mesoderm)

8-10 buds of pharyngeal squamous epithelium grow into the pharyngeal walls —> crypts formed

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41
Q

TONSIL ANATOMY Histo & epithelium

A

Embryology:

Begins 12 weeks

Derived from 2nd pharyngeal pouch endoderm

Lymphocytes migrate into the area (mesoderm)

8-10 buds of pharyngeal squamous epithelium grow into the pharyngeal walls —> crypts formed

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42
Q

TONSIL ANATOMY Zones

A

Zones:

  1. Specialised squamous epithelium (epithelium invaginates as the crypts- increase surface area to compensate for lack of afferents) - Lymphoepithelium = epithelium + lymphocytes + macrophages + dendritic cells (APC) - Captures foreign material from the epithelial surfaces
  2. Parafollicular (T-cell rich) - Dendritic cells present antigens on their cell surface via MHC-II molecules, interacting with CD4+ T cells (assisted by co-stimulatory molecules e.g. CD80)
  3. Mantle zone = lymphocytic cap around the germinal centre (B-cell predominant) - Primed T cells interact with naive B cells with co-stimulatory CD-40 —> B cell proliferation and differentiation - B cells migrate to the lymphoid follicle (forming germinal centres)
  4. Germinal centres (B-cell rich) - B cell proliferation, high affinity mutation, isotype switching and maturation - Produces Plasma cells and memory B cells
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43
Q

TONSIL ANATOMY Difference from lymph node

A

Differences from lymph nodes:

  1. Non-encapsulated
  2. No afferent lymphatic channels

Front-line defense at mucosal site

  • Secretory Ig regulation
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44
Q

SOFT PALATE Innervation

A

Innervation

  • All pharyngeal plexus (IX, X, SNS fibres)
  • SNS fibres are vasoconstrictor
  • Arise in Nucleus Ambiguus
  • Except TVP - Nerve to Medial Pterygoid (V3)

Palatopharyngeal sphincter:

Level of hard palate (C1)

Forms Passavant’s ridge

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45
Q

SOFT PALATE Muscles

A

Made up of 5 paired muscles:

  1. Tensor Veli Palatini Arises outside pharynx - 2 triangles converge on the pterygoid hamulus - Vertical (muscular) - arises from scaphoid fossa (med pterygoid plate), lateral cartilagenous ET, spine of sphenoid - Horizontal (aponeurotic) - attaches to other side, hard palate. Posterior edge is free
  2. Levator Veli Palatini Arises inside pharynx - Arises from petrous apex (ant. to ICA) and medial cartilagenous ET - Inserts to nasal surface of aponeurosis (interdigitates with other side to form a V-shaped sling)
  3. Palatopharyngeus (Palatolaryngeus) post faucial pillar - Arises from 1. nasal surface of aponeurosis and 2. hard palate - Inserts to superior horn of thyroid cartilage and thyroid lamina
  4. Palatoglossus Ant faucial pillar - Arises from under surface of aponeurosis - Interdigitates with Styloglossus
  5. Musculus uvulae - unimportant
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46
Q

SOFT PALATE Histology

A

Histology: Oral surface = stratified squamous epithelium Nasal surface = respiratory epithelium

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47
Q

SOFT PALATE What form’s passavant’s ridge?

A

Palatopharyngeal sphincter:

Level of hard palate (C1)

Forms Passavant’s ridge

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48
Q

OESOPHAGUS 
Def
Parts
Relations in thorax

A

Cricoid cartilage to cardiac orifice of stomach (C6-T10), 25cm long

2 portions

Cervical - Slightly to L of midline, then enters thorax in midline

Thoracic - Slightly to L of midline against vertebral bodies, behind L main bronchus, passes in front of descending aorta (i.e. off vertebrae) in contact with pericardium (L atrium)

Relations in thorax

Crossed by aortic arch on left and azygos vein on right

Crossed anteriorly by L main bronchus and R pulmonary artery

Thoracic duct crosses behind oesophagus (R to L) L atrium

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49
Q

OESOPHAGUS Constrictions

A

Constrictions

15cm - Cricopharyngeus

22cm - Aortic arch

27cm - Left main bronchus

38cm - Diaphragm

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50
Q

OESOPHAGUS Structure

A

Structure

Epithelium- stratified squamous

Muscularis mucosae- thick

Submucosa- sparse mucous glands

Muscular wall- inner circular, outer longitudinal - Skeletal in upper 1/3, visceral in lower 2/3

No serosa (except the short intra-abdominal course)

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51
Q

OESOPHAGUS Blood supply

A

Arterial supply

Upper- Inferior thyroid artery

Middle- Oesophgeal branches of aorta

Lower- Oesophageal branches of L gastric artery

Venous drainage

Upper - Brachiocephalic veins

Middle - Azygos veins

Lower - L gastric vein (to Portal vein)

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52
Q

OESOPHAGUS Nerve supply
Lymph drainage

A

Nerve supply

Upper - RLN

Middle - Unnamed CN X branches

Lower - Oesophageal plexus (CN X branches

Lymph
Follows arteries

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53
Q

BRONCHIAL BRANCHING Overall structure

Blood supply

A

Trachea — Mainstem Bronchi (Primary) — Lobar Bronchi (Secondary) — Segmental bronchi (Tertiary) — Bronchioles — Alveolar duct

Lobar bronchi:

  • 3 on right
  • 2 on left (upper includes lingula segmental bronchi)

Segmental bronchi: Each segmental bronchus enters a pyramid shaped bronchopulmonary segment with its apex pointing towards the hilum

Blood supply:

Artery - bronchial a. from aorta

Venous - Right —> Azygos, Left —> Hemiazygos

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54
Q

BRONCHIAL BRANCHING Left segmental brochi

A

Left side: ASIA ALPS (or ASIA SAMPL)

  1. Upper - Apical - Sup Lingula - Inf Lingula - Anterior
  2. Lower - Anterior - Lateral - Posterior - Superior
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55
Q

BRONCHIAL BRANCHING Right segmental brochi

A

Right side: A PALM Seed Makes Another Little Palm (or A PALM SAMPL)

  1. Upper - Apical - Posterior - Anterior
  2. Middle - Lateral - Medial
  3. Lower - Superior - Medial - Anterior - Lateral - Posterior
56
Q

THYROID 
Def
Surroundings
Immediate relations

A

2 symmetrical lobes +/- pyramidal lobe

  • Joined by the isthmus which attaches to 2nd-4th tracheal rings

Surrounded by visceral portion of MLDCF

  • Thickened as Berry’s ligament (attachment to trachea) Upper pole is limited by sternothyroid thus goitre extends retrosternally rather than superiorly

3 Surfaces:

  • Lateral - Under sternothyroid/sternohyoid
  • Medial - Against larynx/trachea
  • Posterior - Carotid sheath/parathyroids
  • Tubercle of Zuckerkandl (remnant of Ultimobranchial Body) - Posterolateral projection. RLN Nearly always behind this.
  • Sup PT nearly always cranio-posterior to TZ
57
Q

THYROID Course of RLN

A

Recurrent Laryngeal Nerve:

Ascent - Left - in tracheo-oesophageal groove - Right - at an angle (20 degrees) to trachea

Relationship to ITA - Left - more likely behind - Right - 50/50 in front/behind

Always behind pretracheal fascia and therefore Berry’s Ligament

May divide above isthmus - anterior branch will be motor (larger)

58
Q

THYROID Non-recurrent laryngeal nerve

A

Non recurrent RLN

  • Due to anomalies of branchial arteries
  • Come off ~ level with cricoid, behind CCA to CTJ
  • Right - 1% associated with retro-oesophageal subclavian artery (arises from left aortic arch)
  • Left - very rare - assoc with situs inversus & anomalous left SCA
59
Q

THYROID 

Blood supply

A

Arterial supply

  • STA - 1st branch ECA - Divides on the gland (ant/post branches)
  • ITA - thyrocervical trunk, 1st part of SCA - Divides outside the fascia, then multiple branches enter capsule
  • Thyroid ima artery- present in 3% - Variably arises from Brachiocephalic a., R CCA, arch of Aorta

Venous drainage - STV- drains to IJV or Facial v. - MTV- direct to IJV - ITV- Brachiocephalic v.

60
Q

SUPERIOR LARYNGEAL NERVE Anatomy

A

Anatomy

  • Arises from inferior (Nodose) Ganglion
  • Medial to ICA (bifurcates into ext (motor) & int (sensory & autonomic) branch)
  • Internal - Pierces thyrohyoid membrane (with SL artery & vein), divides into upper & lower branch
  • External runs inferiorly over inferior constrictor
  • EBSLN variable couse - Type 1 stays superficial to IC to CT, Type 2 pierces lower IC, Type 3 pierces upper IC
  • Type 3 rarely identified but is protected by IC
  • Type 1 commonly seen over superior pole thyroid (Cernea 2b) - most at risk
61
Q

SUPERIOR LARYNGEAL NERVE 
Locating ext Br SLN

A

Finding EBSLN (Friedman et al)

  • Remove medial 5mm Sternothyroid to ecpose IC & CT
  • Nerve stimulator to identify EBSLN as inserts into CT
  • If runs over IC (type 1) it is followed to preserve it over superior pole (Cernea 2b)
  • If dives into IC low (type 2) no further dissection required (IC protects)
  • Type 3 usually not seen (~20%)
62
Q

SUPERIOR LARYNGEAL NERVE 
Joll’s Triangle
boundaries

Finding nerve within

A

Joll’s Triangle:

  1. Lateral = superior thyroid pole and superior thyroid artery/vein
  2. Superior = Hyoid bone (attachment of fascia and sternothyroid)
  3. Medial = midline
  4. Floor = cricothyroid membrane

Identifying the EBSLN within Joll’s triangle: - Retract gland laterally and develop avascular plane between gland and larynx - EBSLN passes medialy across this space
63
Q

SUPERIOR LARYNGEAL NERVE 
Cernea EB-SLN types

A

Cernea EBSLN types: Aina & Hisham ANZJ Surg, 2001

Type 1: >1cm from upper pole (17%)

Type 2a: <1cm from upper pole (56%)

Type 2b: in contact with upper pole (27%)

Asymmetry in 53% - Increased Type 2a/2b configuration in MNG (superior enlargement of gland) - Preservation still results in 5% voice change (cricothyroid affects pitch) - Loss of high tone and pitch volume and fatigue after extensive use

64
Q

SUPERIOR LARYNGEAL NERVE 
SLN palsy 
- rates
- Symptoms
- exam findings

A

SLN Palsy - Conflicting - up to 20% when not looked for - Bilateral CT paralysis rare (often needs EMG to confirm)

Symptoms - Hoarse / breathy voice - Lack of projection / loudness - Vocal fatigue - Difficulty singing (loss of high pitch control)

Appearance - Shortened cord - Bowing - Height mismatch (inferior displacement) - maybe compensatory muscle tension dysphonia

65
Q

PARATHYROID ANATOMY xxxx

A

Paired superior & inferior glands

35-40mg, 3-8mm 87% 4 glands, 6% 3 glands, 6% 5 glands

Embryology - starts in 5th week

  • Superior PT (PT IV)- 4th pouch endoderm with C cells of thyroid
  • Inferior PT (PT III)- 3rd pouch endoderm with thymus - Position more variable in ectopia, because of longer descent course

Location of the glands Symmetrical in 80%

  • Inferior PT - superficial to RLN. within 1cm inf/post/lat to inferior pole (50%) - Carotid bifurcation to thymus - Identifying branches of ITA is an excellent technique
  • Superior PT - deep to RLN, in a 2cm diameter area centred above crossing of the ITA and RLN, within 1cm of CT joint - More likely to be intrathyroidal (joint origin with C cells) - Very rare to be below main trunk of ITA (i.e. cephalad to ITA) - On or just above RLN at junction of upper/middle 1/3s of gland (when thyroid retracted medially)

Blood Supply

  • Both glands usually receive supply from ITA
  • Occ superior PT receives blood from STA
66
Q

FLOOR OF MOUTH Muscles inc courses

A

Muscles of the FOM:

  1. Mylohyoid - Mylohyoid line to hyoid bone (only the posterior fibres) and midline raphe (most fibres)
  2. Geniohyoid - midline, genial tubercle to hyoid body (lies on top of mylohyoid)

Mylohyoid divides the neck and the mouth

67
Q

FLOOR OF MOUTH Structures between mylohyoid and hyoglossus

A

Structures between mylohyoid and hyoglossus:

1. SM duct - Passes fwd from superficial gland. Opens at sublingual papilla

  1. CN XII - Passes fwd on lower border of hyoglossus - At the anterior border of hyoglossus it becomes flat and gives off branches to the tongue
  2. Lingual Nerve - Enters mouth passing under sup constrictor (at its attachment to PM raphe) - Runs fwd on mylohyoid, dips under SM duct then runs fwd on hyoglossus above the duct - Lingual N runs lat-med, Wharton’s duct runs med-lat - In the FOM the nerve is flattened rather than round
68
Q

FLOOR OF MOUTH Structures deep to hyoglossus:

A

Structures deep to hyoglossus:

  1. Lingual artery - Runs just above greater horn of hyoid (level with CN XII)
  2. CN IX - Disappears under upper part of hyoglossus - Much thinner than CN XII
  3. Stylohyoid ligament - Styloid process to lesser horn of hyoid - Angle between lig and hyoid is the origin of middle constrictor which fans out posteriorly
69
Q

STYLOID APPARATUS Def
parts

A

Part of temporal bone, ossifies in cartilage

Embryologically derived from 2nd branchial arch

2 Ligs

3 Muscles

Stylohyoid ligament - Runs from styloid tip to lesser horn of hyoid - Persistence of perichondrium of Reichert’s cartilage - Styloid process has a variable length

Stylomandibular ligament - Thickening of deep lamina of parotid fascia (SLDCF) - Vaginal process of tympanic bone to angle of mandible - Forms the stylomandibular tunnel (skull base and mandible) where parotid tumours dumb-bell

70
Q

STYLOID APPARATUS 
Ligaments

A

Stylohyoid ligament - Runs from styloid tip to lesser horn of hyoid - Persistence of perichondrium of Reichert’s cartilage - Styloid process has a variable length

Stylomandibular ligament - Thickening of deep lamina of parotid fascia (SLDCF) - Vaginal process of tympanic bone to angle of mandible - Forms the stylomandibular tunnel (skull base and mandible) where parotid tumours dumb-bell

71
Q

STYLOID APPARATUS Muscles

A

Muscles: all have different innervation

  1. Stylopharyngeus- Deepest (medial) and highest (CN IX) Inserts: posterior border of the thyroid lamina and side wall of pharynx
  2. Stylohyoid- arises posteriorly, high up (CN VII) Inserts: splits around digastric tendon, inserts base of greater cornu
  3. Styloglossus- Arises in front and low down (CN XII) Inserts: lateral aspect of tongue, interdigitates with hyooglossus
72
Q

TEMPOROMANDIBULAR JOINT 
Def
Nerve supply

Features

A

Definition: Synovial joint between mandibular head and mandibular fossa (squamous TB)

Features:

  1. Interarticular fibrocartilagenous disc (attaches to capsule)
  2. Capsule
  3. No Hyaline cartilage
  4. Lateral TM lig - Oblique down and back - Tightened by movements away from resting position
  5. Sphenomandibular lig axis of rotation - Spine of sphenoid to lingula of mandible

Nerve supply: Auriculotemporal Nerve (Hilton’s law)

73
Q

TEMPOROMANDIBULAR JOINT 
Movement & 
Stabilisers

A

Stability: Greatest when occluded

  • Preventing forward movement: - Posterior temporalis fibres - Prominence of articular tubercle
  • Preventing backward movement: - Lateral pterygoid contraction - Obliquity of lateral ligament

Movements:

Protraction (LP) / Retraction (Temporalis)

Depression (LP + Digastric) / Elevation (Masseter/MP/Temporalis)

Side-to-side LP on one side, MP on the other

74
Q

ROOT OF THE NECK 

CONTENTS
Relationship to Scalenus Anterior

A

Scalenus Anterior: Key to the root of the neck

  • Anterior tubercles of transverse process - C3-6 —> scalene tubercle (1st rib, upper surface)
  • In line with longus capitis

Relations:

  1. Anterior - Phrenic N (5) - Ascending Cervical A. (Branch of ITA or thyrocervical trunk (15) - Transverse cervical (4) / suprascapular aa (8) - CN X (incl RLN) (14) - IJV - Subclavian V.
  2. Posterior - 2nd part SCA - Scalenus Medius
  3. Lateral - 3rd part SCA - Brachial Plexus
75
Q

ROOT OF THE NECK 

Scalenus Muscles

A

Scalenus Anterior: Key to the root of the neck - Anterior tubercles of transverse process - C3-6 —> scalene tubercle (1st rib, upper surface) - In line with longus capitis 


Scalenus Medius: - Posterior tubercles of transverse process - all Cx vertebrae —> quadrangular area btw neck + subclavian groove of 1st rib

Scalenus Posterior: - Posterior tubercles of transverse process - C4-6 —> 2nd rib

76
Q

ROOT OF THE NECK 
Chassaignac’s triangle

- boundries
- contents

A

Chassaignac’s triangle: Apex TP C6 - compress CCA here

  1. Scalenus Anterior (lat)
  2. Lower fibres of longus colli (med)
  3. Subclavian Artery (base)

Contents - Vertebral art, vein, Stellate Ganglion

77
Q

SUBCLAVIAN ARTERY 

Parts

A

3 parts related to the Scalenus Anterior muscle: Remember VITamin C + D 1st part before scalenus anterior

  1. Vertebral a.
  2. Thyrocervical trunk - Transverse cervical and suprascapular a. (laterally) - Inferior thyroid a. and Ascending Cervical a. (superiorly)
  3. Internal Thoracic a.

2nd part behind scalenus anterior 4. Costocervical trunk - Superior Intercostal a. - Deep Cervical a.

3rd part beyond scalenus anterior 5. Dorsal Scapular a.

78
Q

AXILLARY ARTERY BRANCHES xxxxxx

A

Described in 3 parts related to Pec Minor:

  • Before
  • Behind
  • Beyond

Mnemonic: Sixties Teens Love Sex And Pot

1st part: 1. Superior Thoracic a.

2nd part: 1. Thoracoacromial a. — pierces clavipectoral fascia — clavicular/deltoid/acromial/pectoral branches 2. Lateral thoracic a.

3rd part: 1. Subscapular a. 2. Ant circumflex humeral a. 3. Post circumflex humeral a.

79
Q

CERVICAL SYMPATHETIC TRUNK 
Course

Ganglia

A

Course:

  • Ascends from thorax in front of prevertebral fascia
  • Medial to Vertebral a. and medial to CN X
  • Behind carotid sheath
  • Ends at superior cervical ganglion

Cervical ganglia:

  1. Superior - Lat mass of atlas (grey rami to C1-4)
  2. Middle - Med to carotid tubercle (grey rami to C5-6) - In front of vertebral artery
  3. Inferior - Behind commencement of Vertebral A. (grey rami to C7-8 ie brachial plexus) - Inf and middle connect via the ansa subclavia in front of SCA
80
Q

CERVICAL SYMPATHETIC TRUNK 
Visceral efferents

A

Visceral Efferents:

  1. Cardiac Plexus
  2. Vascular
    - Superior - ICA (Int Carotid N, PPG and eyeball), ECA (pharyngeal plexus, otic/SM ganglia)
    - Middle - Subclavian a. (local branches), ITA (larynx, trachea, hypopharynx, upper oesophagus)
    - Inferior - Vertebral a. - to its branches
81
Q

VASCULAR ANATOMY OF THE NOSE (INTERNAL) 

Supply

A

Internal Carotid Artery System: AEA - branch of Ophthalmic PEA - branch of Ophthalmic

External Carotid Artery System: Facial artery branches - Superior labial artery Internal Maxillary artery branches - SPA. Divides to a septal branch and conchal branch - Greater Palatine artery - descends via GP foramen then ascends through Incisive foramen

Intranasal plexuses: - Kiesselbach’s - anterior septum - Woodruff’s - posterior LNW

Septum distribution: Upper septum - AEA + PEA Posterior / inferior septum - SPA Ant / inferior septum - GPA Caudal septum/columella - Sup labial art

Lateral nasal wall: Superior - AEA Posterior - SPA Anterior - nasal br of facial a (check)

82
Q

VASCULAR ANATOMY OF THE NOSE (INTERNAL) 

Plexuses

A

Intranasal plexuses: - Kiesselbach’s - anterior septum - Woodruff’s - posterior LNW

83
Q

VASCULAR ANATOMY OF THE NOSE (INTERNAL) 

Septum distribution

A

Septum distribution:

Upper septum - AEA + PEA

Posterior / inferior septum - SPA

Ant / inferior septum - GPA

Caudal septum/columella - Sup labial art

84
Q

VASCULAR ANATOMY OF THE NOSE (INTERNAL) 
Lateral wall

A

Lateral nasal wall:

Superior - AEA

Posterior - SPA

Anterior - nasal br of facial a (check)

85
Q

HARD PALATE 
Parts

Foramina

A

Make-up:

  1. Palatal process of maxilla - Pitted surface are insertion of Sharpey’s fibres)
  2. Horizontal process of palatine bone (smooth surface) - Mucous glands between bone and mucosa

Foramina:

  1. Greater palatine - between palatine and maxilla
  2. Lesser Palatine - multiple foramina behind GPF
  3. Incisive - midline anteriorly (GPN/GPA enter nose)
86
Q

HARD PALATE 

Blood & Nerve supply

A

Blood supply: Greater Palatine A.

Nerve supply:

  1. Greater Palatine N.
  2. Nasopalatine N. (anterior)
87
Q

DURAL VENOUS SINUSES xxxx

A

Torcular Herophili or Torcula is the confluence of the sinuses

88
Q

CAVERNOUS SINUS 

Description



A

Spindle-shaped dural venous sinus Volume = 1.5mL

  • No valves in the veins — bidirectional blood flow possible

Extends orbital apex —> petrous apex

Intersected by fibrous bands = tiny ‘caves’ (contrasts with all other dural venous sinuses)

Lies between 2 layers of dura - Outer layer = periosteum of sphenoid bone - Inner layer = covering of temporal lobe

89
Q

CAVERNOUS SINUS 

Relations



A

Relationships:

Medial = sphenoid bone and pituitary fossa

Lateral = Temporal lobe + Meckels’ cave (post/inf)

Anterior = orbital apex (medial end of SOF)

Posterior = cerebral peduncle (PCF contents)

Roof = ICA + uncus of temporal lobe

Floor = greater wing of sphenoid

90
Q

CAVERNOUS SINUS 

Inputs
Outputs
Contents


A

3 sources:

  • Orbit (sup/inf ophthalmic veins)
  • Bony vault (sphenoparietal sinus)
  • Cerebral hemispheres (superficial middle cerebral vein)

3 outputs:

  • Superior petrous sinus
  • Inferior petrosal sinus
  • Vein of Vesalius (to pterygoid plexus either via FO or own foramen medial to FO)

Contents: - ICA - III, IV, V1, V2 (lateral wall, top to bottom) - VI (medial side, below ICA)

91
Q

SCALP Layers

A

5 layers of the scalp:

SCALP pnemonic Skin- thickest in the body (3-7mm)

  • mostly firmly attached by the CT layer to aponeurosis/muscle

Connective tissue - a dense layer

Aponeurosis - includes muslce at either end (occipitalis/frontalis)

Loose areolar tissue - really a subaponeurotic layer (scalping can occur through this layer)

Pericranium - loosely applied to bone but firmly applied to the sutures - Carries blood supply to the cranium

92
Q

SCALP Blood supply

A

Blood supply: free anastomosis between all branches

ECA branches - Occipital a. (runs with greater occipital N, Post auricular a. runs with lesser occipital N.) - Superficial Temporal a.

ICA branches branches of Ophthalmic a. - Supraorbital a. - Supratrochlear a.

93
Q

TEMPORAL FASCIA 

Layers 
- fascia - all tissue layers (ext to internal)

A

There are 3 fascial layers in the temporal region:

  1. Temporoparietal fascia (also known as superficial temporal fascia) - Continuous with SMAS below zygoma)
  2. Deep Temporal fascia, subdivided to: - Superficial layer DTF - Deep layer DTF - These layers surround the temporal fat pad

Layers of the temporal region

Skin

Subcutaneous tissue

Temporoparietal fascia (aka superfical temporal fascia) - continuous with SMAS below, galea aponeurotica above superficial temporal line

Loose areolar tissue

Temporalis muscle fascia (aka deep temporal fascia) - continuous with pericranium. Has 2 lamina which fuse 2 cm above zygomatic arch. (superficial temporal fat pad between lamina) T

emporal muscle

Pericranium Bone

94
Q

SMAS LAYER xxxx

A

Layers of the face:

Skin

Subcutaneous fat

SMAS - superficial musculoaponeurotic system

Muscles

Deep facial fascia (parotidomasseteric fascia - continuous with SLDCF in neck)

Retaining ligaments

Key features of the SMAS:

  1. Divides subcutaneous fat of the face into 2 layers - Non-septate fat (muscles to SMAS) - Septate fat (SMAS to dermis)
  2. Has a consistent relationship with neurovascular structures of the face
  3. Acts as a distributor of force - Attaches to nasolabial fold, perioral and periorbital regions to transmit the forces of facial expression

Relationship of SMAS to VII branches: - Lower face: VII branches are deep to SMAS - innervate facial muscles from undersurface (except levator anguli oris, buccinator and mentalis) - Upper face: nerves penetrate SMAS and thus run superficial to SMAS - sub-SMAS dissection to avoid nerves - Temporal branch of VII: runs within the SMAS

*** NEW STUDY in PRS suggests all branches are deep to SMAS

95
Q

MUSCLES OF THE FACE 
Functional groups

A

Form part of the panniculus carnosus - attached in part to dermis, thus wrinkles the skin

Consist of 3 functional groups- eyelid, nose, lips/cheeks

96
Q

MUSCLES OF THE FACE 
Eyelid

A

Eyelid - Sphincter = Orbicularis oculi - Palpebral - confined to lids. Med palpebral lig to lateral palpebral raphe - Orbital - anterior lacrimal crest and frontal process of maxilla - Dilator = Levator palpebrae superiorus and occipitofrontalis

97
Q

MUSCLES OF THE FACE 
Nose

A

Nose - Sphincter = compressor naris (transverse component of nasalis) - Dilator = dilator naris - Elevator = procerus, lev labii sup alequae nasi - Depressor = depressor septi

98
Q

MUSCLES OF THE FACE 
Lips/cheek

A

Lips/cheeks

  • Sphincter = orbicularis oris - Mental + incisive slips attach to bone, rest forms from Buccinator via the modiolus
  • Buccinator - upper to lower jaw + PM raphe + pterygomaxillary lig
  • Dilators = form the ‘spokes of a wheel’ - Lev labii sup alequae nasi = frontal process maxilla to LLCs + upper lips - Lev labii sup = inferior orbital margin to upper lip - Lev anguli oris = canine fossa to modiolus - Zygomaticus minor = zygomaticomaxillary suture to modiolus - Zygomaticus major = zygomatic bone to modoilus - Risorius = upward extension of platysma to modiolus - Depressor anguli oris = oblique line of mandible to modiolus - Depressor labii inferioris = deep to DAO to lower lip - Mentalis = mental symphysis to skin
99
Q

MUSCLES OF THE FACE 
VII supplies which muscles?

A

Distribution of VII branches:

  1. Temporal — Frontalis
  2. Zygomatic - Upper —> above eye (frontalis and upper 1/2 of orbicularis oculi) - Lower —> below eye (lower 1/2 of orbicularis oculi and muscles below orbit
  3. Buccal — Buccinator and upper lip muscles (OO, LLSAN, LLS, ZMin, Zmaj, LAO, Ris)
  4. Marginal mandibular — Lower lip muscles (OO, DAO, DLI, Mentalis)
  5. Cervical — Platysma
100
Q

NERVE SUPPLY OF THE FACE 

Motor

A

Motor Supply: CN VII

VII divides to temporozygomatic and cervicofacial divisions in parotid - Pes anserinus Emerges as 5 branches

  1. Temporal- Frontalis
  2. Zygomatic- - Upper branch- upper 1/2 of orbicularis oculi - Lower branch- lower half of orbicularis oculi and muscle below orbit
  3. Buccal- buccinator and upper lip muscles (upper 1/2 orbicularis oris and elevators)
  4. Marginal mandibular- Muscles of lower lip
  5. Cervical- platysma
101
Q

NERVE SUPPLY OF THE FACE 

Sensory

A

Sensory supply: CN V branches (except over Ao mandible - GAN)

  1. Ophthalmic - Lacrimal - Upper lateral eyelid - Supraorbital - forehead and scalp to vertex - Supratrochlear - midline forehead - Infratrochlear - medial upper eyelid - External Nasal - middle of external nose down to tip
  2. Maxillary - Infraorbital - - Palpebral- lower eyelid and cheek - Nasal- nasal sidewall and alar - Labial- upper lip and labialgum to 2nd premolar - Zygomaticotemporal - hairless part of the temple - Zygomaticofacial - over zygomatic arch
  3. Mandibular - Auriculotemporal - - Auricular- EAM, surface of TM, pinna above EAM - Temporal- hairy skin over temple - Buccal - ‘thumbprint’ area of skin below zygomatic arch - Mental - skin/mucous membrane of lower lip/gum midline to 2nd premolar
102
Q

VENOUS DRAINAGE OF THE FACE xxx

A

Venous drainage face

Supraorbital, supratrochlear veins → angular vein → facial vein → pierces investing layer of deep fascia → joined by anterior branch of retromandibular vein → IJV → brachiocephalic vein

Superficial temporal vein → joined by maxillary veins (from pterygoid plexus) → becomes retromandibular vein → anterior branch joins facial vein, posterior branch joined by posterior auricular vein → EJV → subclavian vein

Deep venous anastomoses:

B/W facial vein and cavernous sinus (via ophthalmic veins at medial canthus)

B/W facial vein and pterygoid plexus (via deep facial vein in front of masseter)

103
Q

PAROTID GLAND 
Def
Relations

A

Paired glands on either side of face between ear and mandibular ramus

Surrounded by thick capsule derived from SLDCF

Superficial/deep portions arbitrarily divided by CN VII

Relations:

Superior - TMJ, zygomatic arch

Inferior - upper border of SCM (‘parotid tail’)

Lateral - subcutaneous, GAN - GAN branches to anterior and posterior (supplies ear lobe)

Anterior - MP, ramus, masseter

Deep - Mastoid tip (with assoc muscles esp SCM, PBD), styloid (assoc muscles- stylohyoid, stlyoglossus, stylopharyngeus), ECA

104
Q

PAROTID GLAND 
Landmarks VII in Parotid

A

Landmarks for CN VII in Parotid

  1. Posterior belly of digastric (just above its superior border, bisects digastric-mastoid angle)
  2. Tympanomastoid suture
  3. Tragal pointer- 1cm inferior, deep
105
Q

PAROTID GLAND 
Stensen’s duct
- size
- course

A

Stensen’s duct:

5cm long - along a line from intertragal notch to philtrum

Passes fwd across masseter and turns to pierces buccinator

  • Passes submucosal in buccinator before pierces mucous membrane opposite upper 2nd molar
  • Provides a ‘valve’ function
106
Q

PAROTID GLAND 
Histology

A

Histology: predominantly a serous gland

Serous secretory units (acini) drain to intercalated (terminal) ducts

Intercalated ducts converge to form striated (intralobular) ducts which in turn converge to form secretory (interlobular) ducts

Interlobular ducts empty to main parotid duct

107
Q

SUPERIOR ORBITAL FISSURE Boundries

A

SOF forms between greater and lesser wings of sphenoid, tendinous ring = Ligament of Zinn

108
Q

ORBITAL APEX

 Muscle & ligament attachments

A

Lig of Zinn attaches to bone, origin of recti

LR separates SOF into medial & lateral compartments

LPS arises from LWoS inserts sup tarsal plate & skin upper lid

SO arises from narrow tendon body sphenoid, thru trochlea into postero-superior sclera

IO - arises orbital floor beneath trochlea (maxilla) - passes obliquely back to post-inf sclera

All nerves stay within / outside cone except anterior ethmoid / posterior ethmoid / infratrochlear (all branches of nasocilary (V1))

109
Q

LACRIMAL APPARATUS 
Parts

A

Consists of:

  1. Lacrimal gland
  2. Lacrimal canaliculi 

  3. Lacrimal sac

  4. Nasolacrimal duct
110
Q

LACRIMAL APPARATUS 
Describe lacrimal gland
- parts
- location
- Nerve supply

A

1. Lacrimal gland

  • A serous gland made up of two components- orbital (large) and palpebral (small)
  • Lacrimal gland fossa sits in orbital portion of frontal bone - In the lateral part of orbital roof, supported by lateral edge of apopneurotic tendon of LPS
  • Approx 12 ducts lead from palpebral component to superior fornix of conjunctiva



Nerve supply: Sup Salivatory Nucleus —> NI —> GG –> GSPN –> Vidian Nerve –> PPG v—> Zygomatic Nerve (V2) —> lacrimal nerve (v1) —> lacrimal gland

SNS - Sup cervical ganglion

111
Q

LACRIMAL APPARATUS 
Describe lacrimal Canaliculi
- parts
- location
- Nerve supply

A

Lacrimal canaliculi 
puncta lie 6mm from medial canthus

  • Each canaliculus has a 2mm vertical portion and 8mm horizontal portion
  • Superior and inferior join to form the common canaliculus
  • Valved ducts (Valve of Rosenmuller) prevent reflux of tears from the lacrimal sac
112
Q

LACRIMAL APPARATUS 
Describe lacrimal sac
- parts
- location
- Nerve supply

A
  1. Lacrimal sac 12mm x 5mm
    - Lies in its fossa formed by lacrimal grooves of maxilla and lacrimal bone - Relatively higher than previously appreciated — affects surgical approach - 9mm above middle turbinate axilla
    - Crossed in front by medial palpebral ligament and palpebral fibres of OO
    - Muscle contraction causes tears to be ‘sucked’ through the puncta (i.e. during blinking)
    - When the muscle relaxes the lacrimal sac recoils and pumps its contents to the NLD
113
Q

LACRIMAL APPARATUS 
Describe nasolacrimal duct
- parts
- location
- Nerve supply

A

Nasolacrimal duct -

2cm long, slopes downward and laterally to open to inferior metaus - 2cm behind nostril, Hasner’s valve

  • Internal diameter = 3.5mm
  • Mucous membrane is raised into several folds which act as valves to prevent air entering the NLD
114
Q

ORBITAL SEPTUM 
Structure of eyelid

A

Structure of the eyelids: superficial to deep

  1. Loose skin
  2. Orbicularis oculi muscle
  3. Skeletal framework: orbital septum (thickened at the lid margins to form the tarsal plates)
  4. Conjunctiva
115
Q

ORBITAL SEPTUM 
Structure of Tenon’s capsule

A

Tenon’s Capsule:

- Applied to the back of the eye - Extends forward encasing the muscles - Thickenings lateral and medial: - Lateral/medial check ligaments - Joined as the suspensory ligament of Lockwood —> supports the eye

116
Q

ORBITAL SEPTUM 
Description
Attachments

A

Orbital septum:

Attached to the anterior lacrimal crest and margins of the orbit - Wide ‘buttonhole’: the palpebral fissure between the lids

Thickened superiorly and inferiorly - Superior/inferior tarsal plates (dense fibrous tissue)

Septum thickened medially in its attachment to anterior lacrimal crest (medial palpebral ligament) - Lat palp lig is much thinner, fusing with lat palpebral raphe of OO

Contain the tarsal (Meibomian) glands

117
Q

OLFACTORY ANATOMY Epithelium
- type
- cell types
- thickness 
- % airflow reaching cleft


A

Epithelium = pseudo stratified columnar neuroepithelium

  • 70microm thick vs 30microm for resp, Area = 1cm2 (cilia — 22cm2)

10-15% of airflow reaches olfactory cleft

Olfactory epithelium - 5 cell types:

  1. Olfactory neurons- bipolar neurons - One end = knobs for detecting odour (immotile cilia- lack dynein arms) - Other end = projection to olfactory bulb. Synapses in glomerular layer
  2. Microvillar cells - Receptor function (poorly understood)
  3. Sustentacular cells - Maintains ionic milieu. Deactivates odourants. Insulates adjacent receptor cells from each other
  4. Basal cells - deepest layer. Regenerative (3-7 weeks) - Globose cells —> neuron replacement, Horizontal cells —> replace all cell types
  5. Bowman’s glands - Mucus secretion for odour absorption
118
Q

OLFACTORY ANATOMY 
Olfactory nerve supply

A

Unmyelinated axons converge into 15-20 fila (myelinated) to traverse cribriform plate

  • Synapse in glomerular layer (mitral + tufted cells). Convergence
119
Q

OLFACTORY ANATOMY 
Olfactory bulb anatomy & cell types supply

A

Olfactory bulb anatomy:

Divided into 2 layers

  1. Internal plexiform layer = glomerular layer. Mitral/tufted cells
  2. External plexiform layer = granular layer. Granular cells

Olfactory bulb cell types:

  1. Mitral - glomerular layer — lateral olfactory tract
  2. Tufted - glomerular layer. Function unclear
  3. Periglomerular - relay between glomerular cells and granular cells for feedback loops
  4. Granular - inhibitory cells

2nd order neurons project to ipsilateral olfactory cortex (temporal lobe)

120
Q

OLFACTORY ANATOMY 
Olfactory physiology

A

Olfactory physiology:

Largest gene family in the human genome

Codes for > 1000 G-protein receptor type. 7 transmembrane domains with binding site for specific odorants

Vomeronasal Organ: - Anteroinferior septum. Reproductive behaviours in animals. Unknown function in humans

Accessory Inhalant Chemosensory Pathway - V1 and V2 detect irritant stimuli —> Substance P and Calcitonin GRP —> nasal oedema and secretion

121
Q

SINONASAL ANATOMY NUMBERS 

Max sinus
- accessory ostium
- most common adjacent cell

Ethmoid
- Roof thickness of bone (fovea ethmoidalis) - % with agger nasi
- % with ono
- % AEA on mesentery 



A

Maxillary Sinus:

  • Accessory ostium in 25% — defect in mucosal coverage of posterior fontanelle
  • Haller cell most common additional cell

Ethmoid sinus:

  • Roof thickness of bone (fovea ethmoidalis) - Lateral = 0.5mm (orbital plate of frontal bone) - Medial = 0.2mm thick (cribriform plate of ethmoid bone) - 0.05mm at site of AEA canal — thinnest portion of skull base
  • Agger Nasi cell = 90%
  • Onodi cell = 30%
  • AEA on a mesentery + 35%
  • Suprabullar cell = Cell originating in suprabullar region but doesn’t reach frontal sinus
  • Frontal bulla cell = Suprabullar cell that enters the frontal sinus
122
Q

SINONASAL ANATOMY NUMBERS 

Sphenoid sinus - % with ICA dehis
- ICA % septum inserts into canal
-ICA % with >90’ bony exposure
- % optic nerve Dehis



A

Sphenoid sinus:

  • ICA: 20% dehiscent, 40% septum inserts to its canal, >50% have >90 degrees bony exposure
  • Optic nerve: 15% dehiscent, 30% septum inserts to canal
123
Q

SINONASAL ANATOMY NUMBERS 

Sphenoid sinus - landmarks of ostium


A

Finding the sphenoid ostium: medial to superior turbinate in 83%

  1. Junction of upper 2/3 and lower 1/3 of superior turbinate
  2. 12mm above bony choana
  3. 7cm at 30 degree angle from anterior nasal spine
  4. Trans-septal and raised mucosa off front face of sphenoid
  5. Level of roof of the antrum
124
Q

SINONASAL ANATOMY NUMBERS 

Uncinate
- insertions %



A

Uncinate process insertions:

  1. Lamina papyracea 54%
  2. Middle turbinate 34%
  3. Skull base 7%
125
Q

NASAL SEPTUM 
Components xxxx

A

Components: - Cartilage - Perpendicular plate of ethmoid - Vomer - Rostrum of sphenoid contributes small amount - Maxillary crest and crest of palatine bone

126
Q

NASAL SEPTUM 
Blood supply

A

Blood supply:

  1. Posterior nasal artery - branch of SPA
  2. Incisive branch - Greater Palatine artery
  3. Superior labial artery - Facial artery
  4. Anterior ethmoidal artery - Ophthalmic artery
  5. Posterior ethmoidal artery - Ophthalmic artery
127
Q

NASAL SEPTUM 
Nerve supply

A

Nerve supply:

  1. Nasopalatine nerve - branch of PPG
  2. Anterior ethmoidal nerve - from Nasociliary N (V1)
  3. Posterior ethmoidal nerve - from Nasociliary N (from V1)
128
Q

NASAL SEPTUM 
Cottle’s area of septum

A

Cottle’s areas of the septum:

I = external nasal valve

II = internal nasal valve

III = attic of nasal cavity

IV = anterior middle turbinate

V = posterior middle turbinate

129
Q

ANTERIOR ETHMOIDAL ARTERY 
Course
inc terminal branches

A

3rd branch of Ophthalmic artery

Exits orbit through anterior ethmoid foramen (at or above fronto-ethmoidal suture- marks floor of ACF)

Traverses roof of sinus (anteromedial) in the orbitocranial canal to enter the ACF - 30% on a mesentery

Enters ACF at lateral lamella of lamina cribrosa (lateral wall of olfactory fossa)

Curves anteriorly in ethmoidal sulcus (gives off branch to anterior meningeal artery)

Then exits ACF back into nose via cribroethmoidal foramen

Terminal branches are:

  • Anterior nasal artery (sup/med/lat branches)
  • Posterior branch
  • Small meningeal branches

Area of supply: - Previously thought it supplied all of MT (watershed between AEA and SPA territories) - Now thought to supply less of MT

130
Q

ANTERIOR ETHMOIDAL ARTERY 
Landmarks for artery
Retractor for AEA ligation

A

Locating artery in orbit, distances from anterior lacrimal crest (24,36,42)

  • AEA - 24mm
  • PEA- 12mm
  • Orbital apex - 6mm

Use a Ferris-Smith retractor for the Lynch Howarth incision

Area of supply: - Previously thought it supplied all of MT (watershed between AEA and SPA territories) - Now thought to supply less of MT

131
Q

NERVE SUPPLY OF EXTERNAL NOSE xxxx

A

Nerve:

  1. V1 branches - Frontal —> supraorbital and supratrochlear - Nasociliary —> infratrochlear and external nasal (terminal branch of AEN)
  2. V2 branches - ION terminal branches —> palpebral, nasal, labial - ASAN

Also motor supply from CN VII

132
Q

BLOOD SUPPLY OF EXTERNAL NOSE xxxx

A

Blood:

  1. AEA derived - Dorsal Nasal artery
  2. Facial artery derived - Angular artery (terminal branch of facial artery) - Lateral nasal artery - Columellar artery (branch from superior labial artery)
133
Q

CSF ANATOMY 
- parts of Ventricular system 


A

Anatomy of the ventricular system:

2 lateral ventricles –> Foramen of Monro –> 3rd ventricle –> cerebral aqueduct of Sylvius –> 4th ventricle — 2x Foramen of Luschka and 1 x Foramen of Magendie —> subarachnoid space

  • Luschka — subarachnoid space via the pontine cisterns
  • Magendie — subarachnoid space via the cerebello-medullary cistern

Arachnoid villi - situated along the cerebral convexities

  • Project into the dural sinuses and act as one-way valve
  • Valve will close when pressure <1.5 cm H2O
134
Q

CSF Physiology 
- volume
- Produced/day
- where made
- constituents

A

CSF Physiology:

Production = 450mL/day,

Total volume = 150mL — turned over 3x/day

Produced in choroid plexus 50% and walls of lat/3rd/4th ventricles 50%

Filtrate of venous blood, modified by ependymal cells - Slightly higher NaCL, Lower K+, Glu, Ptn

Normal ICF pressure = 5-15 cmH2O

Absorbed by arachnoid villi (90%) and direct to cerebral venules (10%)

135
Q

CSF 
B2 tranferrin


A

B-2 transferrin:

Produced by desialisation of B1 transferrin (by cerebral neuraminidase)

Found in CSF, perilymph, vitreous humour

High sensitivity and specificity for CSF from nasal secretions - Stable at room temperature for 7 days (Bleier et al)

136
Q
A

*RACS ENT Fellowship (19 decks)

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