First Test 151102 Flashcards
Parietal bones (2)
Form side/roof of cranial cavity
Temporal bones (2)
Form the lateral aspects/ floor of cranium
Occipital bone
Forms posterior part and most of base of cranium
Sphenoid bone
Wedge-shaped, lies at the middle part of the base of skull
butterfly-shaped
Ethmoid bone
Anterior part of cranial floor, medial to orbits
- major superior supporting structure of the nasal cavity
- contains projections (conchae), lined by mucous membranes
- increased surface area in nasal cavity, humidifies inhaled air, traps inhaled particles
Define suture
Immovable joints that fuse most of skull bones together
What are the paranasal sinuses?
- 4 pairs of air filled spaces surrounding the nasal cavity
- secretions produced by the mucous membranes (which line the sinuses), drain into the nasal cavity
- serve as resonating chambers that intensify and prolong sounds
How many bones does the skull consist of?
22 bones
- 8 cranial bones
- 14 facial bones
Define foramen
Openings that allow veins, ligaments and nerves to pass
Define fissures
Narrow groove/division/furrow between adjacent bones through which blood vessels or nerves pass (eg superior orbital fissure)
Define fossa
Shallow depression (for glands etc. lacrimal fossa for lacrimal gland
Nasal bones
form the bridge of the nose
maxillae
- form the upper jawbone
- forms most of the hard palate
- separates the nasal cavity from the oral cavity
zygomatic bones
commonly called cheekbones, form the prominences of the cheeks
lacrimal bones
form a part of the medial wall of each orbit, smallest in face
palatine bones
form the posterior portion of the hard palate
inferior nasal conchae
scroll-like bones, form a part of the inferior lateral wall of the nasal cavity and help filter air before reaching lungs
vomer
inferior portion of nasal septum, triangular
mandible
jawbone, largest, strongest facial bone. The only movable skull bone
nasal septum
divides the interior of the nasal cavity into right and left sides
define orbits
eye sockets
hyoid bone
- does not articulate with any other bone
- supports tongue, providing attachment sites for muscles of tongue, neck and pharynx
- also helps larynx (voice box) open at all times
define sinuses
air cavities within bones, relieve pressure
name other cavities besides the large one (3 main ones)
- nasal cavity
- orbits
- paranasal cavities
- small cavities (contain organs involved in hearing and equilibrium
name the bones of the orbit (7)
- frontal bone
- sphenoid bone
- palatine bone
- zygomatic bone
- ethmoid bone
- lacrimal bone
- maxilla
define fontanels
- areas of unossified tissue
- at birth, fontanels (commonly called soft spots) link the cranial bones
- eventually, they are replaced with bone to become sutures
- provide flexibility to the foetal skull, allowing skull to change shape as it passes through the birth canal
what is craniosynotosis
(premature cranial suture fusion) = abnormal skull shape, blindness, retardation. seriousness depends on sutures involved and early diagnosis
name the four paranasal sinuses
- frontal sinus
- maxillary sinus
- ethmoid sinuses (anterior and posterior)
- sphenoid sinus
roles of sinuses
- immunological defense
- lightening of skull
- increasing surface area for smell (olfaction)
- increasing voice resonance
- buffer against facial trauma
- humidifying & heating inhaled air
- regulating intranasal pressures
name one facial nerve
7th (VII) cranial nerve
define Bell’s Palsy
facial paralysis due to nerve damage (eg. infection)
role of orbicularis oculi (muscle)
closes eye
role of levator palpebrae superioris (muscle)
opens the eye / raises lid
role of orbicularis oris (muscle)
puckers the mouth
role of buccinator (muscle)
forms muscular portion of the cheek and assist in whistling, blowing, sucking and chewing
annulus of zinn
most extraocular muscles arise from here (all except from inferior oblique)
name 3 cranial nerves that innervate the EOMs
- oculomotor nerve (CNIII) - superior, medial, inferior rectus and inferior oblique
- Trochlear nerve (CNIV) - superior oblique
- abducens nerve (CNVI) - lateral rectus
define adduction
eye moves inward, towards the nose
define abduction
eye moves outwards, away from nose
define intorsion
rotates top of eye towards the nose
define extorsion
rotates top of eye away from nose
define elevation
moves eye up
define depression (eye movement)
moves eye down
role of superior oblique
rotates eye, pulls eye downwards + medially (intorsion, depression, adduction)
role of inferior oblique
rotates eye, pulls eye upwards and laterally (extorsion, elevation and abduction
role of lateral rectus
moves eye outwards, abduction
role of medial rectus
moves eye inwards, adduction
role of superior rectus
raises eye, elevation, intorsion, adduction
role of inferior rectus
moves eye downwards, depression, extorsion, adduction
define trochlea
a loop of fibrous tissue that superior oblique tendon passes through. the trochlea exerts pressure used in pulley system
SO is the only EOM innervated by the Trochlear nerve (4th cranial nerve)
Frontal bone
Forms forehead
Define transduction
The retina: light -> electrical potential
The retina: encoding
Electrical potentials -> action potential sequences for retinal output