Anatomy Topic 3 Case 3 Flashcards
Identify six contents of the orbit
- Eyeball
- Optic nerve
- Extra-ocular muscles
- Lacrimal apparatus
- Adipose tissue and fascia
- Nerves and vessels supplying these structures
Identify seven bones that make up each orbit
- Maxilla
- Zygomatic
- Frontal
- Ethmoid
- Lacrimal
- Sphenoid
- Palatine
Identify the layers of the eyelids from superficial to deep
- Skin
- Subcutaneous tissue
- Voluntary muscle
- Orbital septum
- Tarsus
- Conjunctiva
Which muscle closes the eyelids?
- Orbicularis Oculi
Identify the two parts of the orbicularis oculi
- Orbital part, which surrounds the orbit
- Palpebral part, which is in the eyelids
Which nerve innervates the orbicularis oculi?
- Facial nerve
Identify the two ligaments associated with the orbicularis oculi
- Medial palpebral ligament
- Lateral palpebral ligament
What is tarsus and its function?
- Dense connective tissue
- Provides major support for the eyelid
What are the attachments, innervation and function of the levator palpebrae superioris muscle?
- Origin: Posterior part of roof of orbit
- Insertion: Anterior surface of superior tarsus muscle
- Innervation: Superior branch of oculomotor nerve
- Function: Raises the eyelid
What are the attachments, innervation and function of the superior tarsus muscle?
- Origin: Inferior surface of levator palpebrae superioris
- Insertion: Superior tarsus
- Innervation: Postganglionic sympathetic fibres from the superior cervical ganglion
- Function: Raises the eyelid
What is ptosis?
- Drooping of the eyelid
- Caused by loss of function of either the levator palpebrae superioris or superior tarsal muscle
Where are the tarsal glands located and what is their role?
- Embedded into tarsal plates
- Increase viscosity of tears
- Decrease rate of evaporation of tears
What is chalazion?
- Blockage and inflammation of the tarsal gland
What is a stye?
- Blockage and inflammation of sebaceous and sweat glands associated with eyelash follicles
What is the conjunctiva?
- Thin membrane that covers the posterior surface of each eyelid
What is the sclera?
- Outer surface of each eyeball
Outline the arterial supply of the eyelids
- Ophthalmic artery
- Facial artery
- Superficial temporal artery
Outline the venous drainage of the eyelid
- Ophthalmic veins
Outline the lymphatic drainage of the eyelid
- Mainly parotid nodes
- Some submandibular nodes
Outline the sensory innervation of the eyelids
- All branches of the trigeminal nerve
Outline the motor innervation of the eyelids
- Facial nerve: orbicularis oculi
- Oculomotor nerve: levator palpebrae superioris
What is the role of the lacrimal apparatus?
- Production, movement and drainage of fluid from the surfaces of the eyeball
Outline the components of the lacrimal apparatus
- Lacrimal gland
- Lacrimal canaliculi
- Lacrimal sac
- Nasolacrimal duct
Identify the two parts of the lacrimal gland
- Orbital part, in the lacrimal fossa
- Palpebral part, inferior to levator palpebrae superioris
What drains the lacrimal lake?
- Lacrimal canaliculi
- Via the opening called the lacrimal punctual
What is the arterial supply and venous drainage of the lacrimal gland?
- Ophthalmic artery and vein respectively
Outline the sensory innervation of the lacrimal gland
- Ophthalmic nerve
Outline the parasympathetic innervation of the lacrimal gland
- Neurons leave CNS via facial nerve and enter greater petrosal nerve
- Enter nerve of pterygoid canal
- Joints pterygopalatine ganglia
- Postganglionic neurons join the maxillary nerve
- Branches off as zygomatic nerve
- Which gives rise to zygomaticotemporal nerve
- Branches off as lacrimal nerve
What does the optic canal open into?
- Middle cranial fossa
What is contained within the optic canal?
- Optic nerve
What is contained within the superior orbital fissure?
- Ophthalmic branch of trigeminal nerve
- Oculomotor nerve
- Trochlea nerve
- Abducens nerve
- Superior ophthalmic vein
What is periorbita and its significance in relation to the rectus muscles?
- Periosteum lining the orbit
- Thickens posteriorly to form the common tendinous ring
- Which is the point of origin of the rectus muscles
What is the bulbar / fascial sheath of the eyeball?
- Layer of fascia that encloses the major part of the eyeball
- Suspensory ligament supports the eyeball
What are the check ligaments of the eye?
- Expansions of investing fascia covering medial and lateral rectus muscles
- They restrict the medial and lateral rectus muscles
What are the attachments, action and innervation of the superior rectus?
- Origin: Superior part of common tendinous ring
- Insertion: Anterior half of eyeball superiorly
- Innervation: Superior branch of oculomotor nerve
- Function: Elevation, adduction and medial rotation of eyeball
What are the attachments, action and innervation of the inferior rectus?
- Origin: Inferior part of common tendinous ring
- Insertion: Anterior half of eyeball inferiorly
- Innervation: Inferior branch of oculomotor nerve
- Function: Depression, adduction and lateral rotation of eyeball
What are the attachments, action and innervation of the medial rectus?
- Origin: Medial part of common tendinous ring
- Insertion: Anterior half of eyeball medially
- Innervation: Inferior branch of oculomotor nerve
- Function: Adduction of eyeball
What are the attachments, action and innervation of the lateral rectus?
- Origin: Lateral part of common tendinous ring
- Insertion: Anterior half of eyeball laterally
- Innervation: Abducens nerve
- Function: Abduction of eyeball
What are the attachments, action and innervation of the superior oblique?
- Origin: Sphenoid bone, superomedial to optic canal
- Insertion: Outer posterior quadrant of eyeball (superior surface)
- Innervation: Trochlea nerve
- Function: Depression, abduction and medial rotation of eyeball
What are the attachments, action and innervation of the inferior oblique rectus?
- Origin: Maxilla bone, lateral to nasolacrimal bone
- Insertion: Outer posterior quadrant of eyeball (inferior surface)
- Innervation: Inferior branch of oculomotor nerve
- Function: Elevation, abduction and lateral rotation of eyeball
Why is a patient asked to track a physician’s finger laterally when testing the rectus muscles?
- Axis of each orbit is directed laterally from back to front
- But each eyeball is directed anteriorly
- Lateral movement brings the eyeball into alignment with the long axis of the superior and inferior rectus muscles
What is the arterial supply and venous drainage of the orbital structures?
- Ophthalmic artery (branch of internal carotid artery)
- Superior and inferior ophthalmic veins
What is the cornea?
- Transparent outward projection of the eyeball
What is the anterior chamber?
- Area directly posterior to cornea
What is the iris?
- Coloured part of the eye
What is the pupil?
- The opening between the iris and anterior chamber
What is the posterior chamber?
- Area anterior to lens
- And posterior to iris
Describe the pathway taken by aqueous humor
- Secreted into posterior chamber
- Flows into the anterior chamber through the pupil
- Absorbed into the canal of Schlemm
What is the function of aqueous humor?
- Supplies nutrients to the avascular cornea and lens
- Maintains intra-ocular pressure
What is the vitreous chamber?
- Posterior four-fifths of eyeball
- Posterior to the lens and anterior to the retina
- Contains vitreous humor
What does the outer fibrous layer of the eye consist of?
- Cornea anteriorly
- Sclera posteriorly
What does the middle vascular layer of the eye consist of?
- Choroid posteriorly
- Which is continuous with the ciliary body posteriorly
- And the iris anteriorly
What does the inner layer of the eye consist of?
- Retina posteriorly
- Iris anteriorly
Outline the arterial supply of the eyeball
- Short and long posterior ciliary arteries
- Anterior ciliary arteries
- Retinal artery
Outline the venous drainage of the eyeball
- Vorticose veins arising from the choroid layer
- Which enter superior and inferior ophthalmic veins
Outline the location, innervation and function of the ciliary muscle
- Location: Ciliary muscle
- Innervation: Parasympathetics from oculomotor nerve
- Function: Constricts ciliary body, relaxes tension on lens, which becomes more rounded
Outline the location, innervation and function of the sphincter pupillae
- Location: Circularly around the fibres in the iris
- Innervation: Parasympathetics from oculomotor nerve
- Function: Constricts pupil
Outline the location, innervation and function of the dilator pupillae
- Location: Radially arranged fibres in the iris
- Innervation: Sympathetics from superior cervical ganglion
- Function: Dilates pupil
Identify the two parts of the inner layer of the eyeball, and the junction between these parts
- Posteriorly: Optic part of retina
- Anteriorly: Non visual part covering the internal surface of the ciliary body and iris
- Ora serrata
Identify the two parts of the optic part of the retina
- Pigmented layer firmly attached to the choroid
- Inner neural layer attached to the pigmented layer around the optic nerve
What is the optic disc?
- Point at which the optic nerve leaves the retina
- Possesses no rods so is referred to as a blind spot
What is the macula lutea
- Region of the retina with highest visual sensitivity
- Located lateral to the optic disc
- Possesses a central possession, the fovea centralis
- Because it has fewer rods and more cones
What are the nares?
- Anterior apertures of the nasal cavities
What are the choanae?
- Posterior apertures of the nasal cavities
How are the nasal cavities separated from:
[A] Each other
[B] Oral cavity
[C] Cranial cavity
- [A] Midline nasal septum
- [B] Hard palate
- [C] Frontal, ethmoid and sphenoid bones
For each of the following, identify the lining, the contents and position within the nasal cavity:
[A] Vestibule
[B] Respiratory
[C] Olfactory
- [A] Skin, vibrissae, positioned anteriorly
- [B] Respiratory epithelium, ciliated and mucous cells, positioned posteriorly
- [C] Olfactory epithelium, olfactory receptors, positioned superiorly
Outline four functions of the nasal cavities
- Sense of smell
- Adjusting temperature and humidity by action of rich blood supply
- Trap and remove particulate matter by filtering the air through air
- Move mucus posteriorly by cilia to be swallowed
What are the conchae and where are they positioned and what is their function?
- Three laterally curves shelves of bone
- Which separate the nasal cavity into four air channels and increase the surface area of contact between tissues of the lateral wall and the respired air
- Inferior nasal meatus
- Middle nasal meatus
- Superior nasal meatus
- Spheno-ethmoidal recess
Identify 5 bones that make up the lateral wall of the nasal cavity
- Frontal process of maxilla
- Concha from ethmoid bone
- Lacrimal bone
- Perpendicular plate of palatine bone
- Medial pterygoid process of sphenoid bone
Identify 3 structures that make up the medial wall of the nasal cavity
- Septal cartilage anteriorly
- Perpendicular plate of ethmoid bone superiorly
- Vomer posteriorly
Identify 4 bones that make up the roof of the nasal cavity
- Nasal bone
- Nasal spine of frontal bone
- Cribiform plate of ethmoid bone
- Alae of vomer
Describe the structure of the hard palate
- Bony plate covered above and below by mucosa
- Above it is covered by keratinised stratified squamous epithelium and forms the floor of the nasal cavity
- Below it is covered by a tightly bound layer of oral mucosa and forms the roof of the oral cavity
What are palatine rugae?
- Transverse palatine folds of the hard palate in the oral cavity
What is the palatine raphe?
- Medial longitudinal ridge pf the hard palate in the oral cavity
- Which ends anteriorly in a small oval elevation known as the incisive papilla
What is the function of the soft palate?
- Acts as a valve that can be depressed to close the oropharyngeal isthmus
- Or elevated to separate the nasopharynx from the oropharynx
What are the attachments, innervation and function of the tensor veli palatini muscle?
- Origin: Scaphoid fossa of sphenoid bone
- Insertion: Palatine aponeurosis
- Innervation: Mandibular branch of trigeminal nerve
- Function: Tenses the soft palate, opens the auditory tube
What are the attachments, innervation and function of the levator veli palatine muscle?
- Origin: Petrous part of temporal bone anterior to opening for carotid canal
- Insertion: Superior surface of palatine aponeurosis
- Innervation: Vagus nerve via pharyngeal branch to pharyngeal plexus
- Function: Elevates the soft palate above the neutral position
What are the attachments, innervation and function of the palatopharyngeus?
- Origin: Superior surface of palatine aponeurosis
- Insertion: Pharyngeal wall
- Innervation: Vagus nerve, via pharyngeal branch to pharyngeal plexus
- Function: Depresses soft palate, moves palatoglossal arch toward midline, elevates back of the tongue
What are the attachments, innervation and function of the palatoglossus?
- Origin: Inferior surface of palatine aponeurosis
- Insertion: Lateral margin of tongue
- Innervation: Vagus nerve, via pharyngeal branch to pharyngeal plexus
- Function: Depresses soft palate, moves palatoglossal arch toward midline, elevates back of the tongue
What are the attachments, innervation and function of the musculus uvulae
- Origin: Posterior nasal spine of hard palate
- Insertion: Connective tissue of uvula
- Innervation: Vagus nerve, via pharyngeal branch to pharyngeal plexus
- Function: Depresses soft palate, moves palatoglossal arch toward midline, elevates back of the tongue
Identify the cartilages that make up the external nose
- Lateral processes of septal cartilage
- Superior margin of septal cartilage
- Major alar cartilage
- Minor alar cartilages
How are the nares held open?
- Alar and septal cartilage
- Inferior nasal spine
- Adjacent margins of maxillae
Identify the features of the ethmoid bone
- Two ethmoidal labyrinths containing ethmoidal cells
- Cribiform plate
- Perpendicular plate
Where do the anterior ethmoidal cells open?
- Frontonasal duct, which opens onto middle nasal meatus
Where do the middle ethmoidal cells open into?
- Ethmoidal bullae
Where do the posterior ethmoidal cells open into?
- Lateral wall of the superior nasal meatus
Outline the innervation of the ethmoidal cells
- Anterior and posterior ethmoidal branches of the nasociliary nerve
- Which arise from the ophthalmic nerve
Outline the arterial supply of the ethmoidal cells
- Anterior and posterior ethmoidal arteries
Outline five possible roles of the paranasal sinuses
- Deceasing relative weight of front of skull
- Providing a buffer against blows to face
- Insulate sensitive structures like dental roots and eyes
- Humidifying and heating inhaled air because of slow air turnover,
- Increasing resonance of voice.
Which nasal sinuses are largest
- Maxillary
Which nasal sinuses are located most superiorly?
- Frontal
Where do the frontal sinuses open onto, and what is their arterial supply and innervation?
- Lateral wall of middle meatus via frontonasal duct
- Branches of ophthalmic nerve
- Anterior ethmoidal arteries
Where do the maxillary sinuses open onto, and what is their arterial supply and innervation?
- Lateral wall of middle meatus
- Branches of maxillary nerve
- Maxillary arteries
Where do the sphenoid sinuses open onto, and what is their arterial supply and innervation?
- Spheno-ethmoidal recess
- Ophthalmic nerve
- Maxillary arteries
Outline the arterial supply of the nasal cavities
- Sphenopalatine artery supplying medial wall
- Greater palatine artery supplying floor
- Superior labial artery supplying anterior regions
- Ethmoidal arteries supplying lateral walls
Into which veins do the veins of the nasal cavities ultimately drain
- Pterygoid plexus of veins in the infratemporal fossa
Which nerves provide sensory innervation of the nasal cavities?
- Ophthalmic (V1)
- Maxillary (V2)
Which nerves provide secretomotor innervation of glands in the mucosa of the nasal cavity and the paranasal sinuses?
- Greater petrosal branch of facial nerve
Lymph from anterior regions of the nasal cavities drain into which nodes?
- Submandibular nerves
Lymph from posterior regions of the nasal cavities drain into which nodes?
- Deep cervical nodes
- Into the retropharyngeal nerves
How are tears drawn into the nasolacrimal duct from the lacrimal sac?
- Contraction of the orbicularis oris during blinking
- Puts pressure on lacrimal sac
