1 - Anatomy & Embryology Flashcards

Question 1

Q

Orbital Landmarks

Whitnall’s Tubercle

Distances of optic canal and ethmoid foramen

Answer

A

Whitnall’s Tubercle

1cm inferior and 0.5cm deep from ZF suture
Lockwood suspensory ligament
Lateral check ligament
Lateral canthal ligament
Lateral limb of Levator palpebrae superioris

Distances

From anterior lacrimal crest
- 24mm - Anterior ethmoidal foramen
- 36mm - 12mm from Ant eth f. - Posterior ethmoidal foramen
- 42mm - 6mm from Post eth f. - Optic canal

Question 2

Q

Orbital Anatomy

Orbital volume
Globe volume
Anterior chamber volume
Age which orbit stop growing

Answer

A

Clinical head and neck anatomy for surgeons

Orbital volume - 30cm2
Globe volume - 6-7cm2
Inferior orbital foramen - 5-10mm below inferior rim
- T.Turvey - 5mm
- B.Evans - 7-10mm
  *

Question 3

Q

Marginal Mandibular Nerve Anatomy

Answer

A

Dingman and Grabb
- 100 facial halves
- Relationship with inferior border of mandible
  - 81% above
  - 19% below - 1cm lowest point
- Relationship to:
  - Facial artery
    - 0% below lower border anterior to Artery
    - Can deep or superficial to the Facial Artery
  - Facial vein
    - 98% Superficial to Posterior facial vein (Anterior limb of Retromandibular vein)
    - 100% Superficial to Anterior facial vein (Facial vein)
- Branches
  - 21% - Single
  - 67% - 2 Branches
  - 9% - 3 Branches
- Anastomoses
  - 5% - with Buccal branches
Ziarah and Atkinson
- 110 facial halves
- Relationship to lower border of mandible
  - 0.6cm to 1.2cm below
- Relationship to:
  - Facial Vein
    - 100% superficial to Facial vein
  - Facial Artery
    - 53% below the lower border of mandible
    - 6% continued up to 1.5cm anterior to Facial Artery
- Branches
  - 35% - Single
  - 53% - 2 Branches
  - 11% - 3 Branches
- Anastomoses
  - 8% - with Buccal branches

Question 4

Q

Facial Nerve Localisation

Answer

A

Facial Nerve Localisation

Advantages vs Disadvantages
- Anterograde
  - Methodical
  - Trunk identified and protected
  - All peripheral branches are identified
- Retrograde
  - Small peripheral lesion in parotid gland
  - Limited dissection
    - Lower drain output -> shorter inpatient stay
    - Less chance of Facial nerve trunk injury
  - Useful in patients who have already had a superficial parotidectomy
Antegrade
- Tragal Pointer
  - 1cm inferior and 1cm deep
  - Soft tissue landmark - less reliable
- Typanomastoid suture
  - 2-5mm inferior to the suture
  - The suture will lead to the Stylomastoid Foramen
  - Palpate the suture - finger will point towards the nerve trunk
- Posterior belly of Digastric
  - Facial nerve exits just deep and medial to the PBD
    Classically lies in the same plane
Retrograde
- Posterior auricular branch - Keefe 2009
  - Overlies the mastoid process, deep to fat
  - Relatively large nerve and easy to identify
- Buccal Branch
  - Runs parallel to and 1cm below the zygomatic arch diverging distally towards the corner of the mouth
  - Parotid duct runs just inferior to the buccal branch
- Marginal mandibular
  - Lies within 1cm of the angle of the mandible as it exits the parotid gland
  - Lies within a few mm of the anterior communicating vein of the retromandibular as it exits the tail of the parotid

Question 5

Q

Orbital Complication

Answer

A

Blindness

Ord 1981
- 3:1000
- Retinal artery spasm or ischaemia from compression from oedema

Question 6

Q

Orbital bony anatomy

Bones
Fissures
Fissure Contents

Answer

A

Bones of the orbit

Lacrimal
Sphenoid
Ethmoid
Frontal
Maxilla
Zygoma
Palatine

Superior orbital fissure

Bones
- Greater and Lesser wings of the sphenoid
- Maxilla
Contents
- Within the Common tendinous ring
  - Nerve
    - III
      - Superior branch of Oculomotor
      - Inferior branch of Oculomotor
    - V1
      - Nasociliary
    - VI
- Outside the Common tendinous ring
  - Nerve
    - III
    - IV
    - V1
      - Lacrimal nerve
      - Frontal nerve
  - Vein
    - Superior ophthalmic vein

Inferior orbital fissure

Bones
- Zygoma
- Maxilla
- Palatine
- Ethmoid
Bisected by the infra-orbital nerve fissure
- Laterally the IOF communicates with the Infra-temporal fossa
- Medially the IOF communicates with the Pterygopalatine fossa
Contents
- Nerve
  - Zygomatic nerve
- Vein
  - Inferior ophthalmic vein

Question 7

Q

Orbital Anatomy - Eyelid & Canthal attachment

Eyelid anatomy

Whitnall’s ligament

Medial Canthal Attachment

Lateral Canthal Attachment

Answer

A

Upper eyelid

Lower eyelid

Tasal plates

Upper tarsal plate - 10mm
Lower tarsal plate - 5mm

Question 8

Q

Lingual Nerve Position at 3rd Molar Region

Question 9

Q

Sinus Embryology

Answer

A

Development
- Maxillary, Ethmoid and Frontal sinus develops from invaginations of the nasal cavity
- Spenoid sinus froms from the closure of the spheno-ethmoidal recess
Pneumatization
- Primary pneumatization
  - Initial invagination of the sinus by mucosal cells
- Secondary pneumatization
  - Expansion and growth of the sinus
  - NB: Some sources say sinuses are not present until an air filled cavity occurs (secondary pneumatization)
    Does not mean primary pneumatization has not occured
Maxillary Sinus
- Primary pneumatization
  - 3rd month in utero
  - Invagination of the ethmoid infundibulum into the lateral walls of the middle meatus
- Secondary pneumatization
  - Grows to maximum size until mid teens
Frontal Sinus
- Primary pneumatization
  - 4th month in utero
  - Develops from two independent spaces
    - Expansion of the ethmoid sinus into the Frontal bone
    - Invagination of the middle meatus of the nasal passage
- Secondary pneumatization
  - Grows to maximum size until mid teens
Ethmoid Sinus
- Primary pneumatization
  - 4th month in utero
- Secondary pneumatization
  - Grows to maximum size until mid teens
Sphenoid Sinus
- Primary pneumatization
  - No primary pneumatization
  - Forms by constricting the posterosuperior portion of the spheno-ethmoidal recess
- Secondary pneumatization
  - 2 - 3 yrs of age until mid teens

Question 10

Q

Skin Layers

Answer

A

Epidermis
- Stratum basale
  - Contains the only keratinocytes capable of dividing
- Stratum spinosum
  - Keratinocytes become spiny shaped
  - Langerhans cells and immune active cells are located in this layer
- Stratum granulosum
  - Keratinocytes loose their nucleus and cytoplasm and appear granular
- Stratum lucidum
  - Typically only found in the thicker parts of skin - palms & soles
- Stratum corneum
  - Anucleated cells filled with keratin
  - Barrier function of the epidermis
Dermis
- Papillary Dermis
  - Provides nutrients to the epidermis
  - Contains rich plexus of vessels
- Reticular Dermis
  - Serves to strengthen the skin and provide it with elasticity
  - Exocrine glands, Sebaceous glands and nerve endings are found within this layer

Question 11

Q

Salivary Gland Anatomy and Physiology

Answer

A

Anatomy
Three subunits of a salivary gland
- Acinus
  - Serous - Parotid mostly serous
  - Mucous - Sublingual and Minor salivary glands
    - von Ebner Glands - Serous (Amylase)
  - Mixed - Submandibular gland
- Secretory duct
  - Intercalated ducts - Leading from the acini to the striated duct
  - Striated ducts -
- Collecting duct
Salivary Production
- Electrolytes are actively transported under neuronal and hormonal control
  Fluid is osmotic
- Hypotonic
- Salivary flow
  - Unstimulated: 0.1-0.3mL/min
    Forms 10-20% of daily saliva production
    - Submandibular gland accounts for 70% of unstimulated production
  - Stimulated: 0.2 - 7mL/min
    Forms 80-90% of daily saliva production
    - Parotid gland accounts for 2/3rd of stimulated saliva production
  - Sublingual and Minor salivary glands are both spontaneous secretors
    Produces a continuous flow of mucus in the absence of neural stimuli

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1 - Anatomy & Embryology Flashcards

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