Surface anatomy and the skull Flashcards
How many bones are in the skull
22
Which bones are excluded from the skull?
the ossicles - tiny bones in middle ear cavity
Give 2 single bones
mandible and sphenoid bone
Give 4 paired bones
maxilla, palatine, temple and zygomatic bone
What is the cranium
the skull WITHOUT the mandible (ie 21 bones)
What does the cranium have
1) the case of bone which encloses the brain (THE BRAIN CASE)
2) the base of the skull
3) part of facial skeleton hanging from undersurface of base of skull
What part does the mandible contribute to
rest of the facial skeleton
In the mandible, what is the condylar process, where does it lie and what does it have
1) part of the TMJ
2) more posteriorly
3) a head and a neck
In the mandible, what is the coronoid process, where does it lie
1) process attaching temporalis muscle
2) more anterior
How does the mandible connect to the cranium?
by the left + right TMJs
In the mandible, what is the ramus of the mandible
large quadrilateral portion located posterior to the teeth
mandible has a right and a left ramus (each with its own condylar and coronoid process)
What is the temporalis muscle?
large muscle on side of head which is used in biting
In the mandible, what is the angle of the mandible
the inferior corner of the ramus of the mandible
In the mandible, what is the mental foramen, where does it lie, give the greek origin
1) transmits the mental nerve (a sensory nerve which is a branch of the IA nerve) which supplies some of the soft tissues in chin region
2) near the chin
3) mentum is greek for chin
In the mandible, what are the mandibular foramina, where do they lie
1) transmit the right and left… IA nerve, artery + vein
2) one in the inner surface of each ramus
In the mandible, what is the body of the mandible
part of the mandible with the teeth in it (everything anterior to the ramus)
What role does the IA nerve have
supplies all lower teeth + some gingivae on their labial and buccal aspects
What is an IA nerve block (aka inferior dental block)
where you anaesthetise the IA nerve as it emerges from the mandibular foramen
most common nerve block used in dental practice
In the mandible, what are alveolar ridges
alveolar bone running round upper surface of body of mandible surrounding roots of teeth
In the mandible, what is the mandibular notch / fossa?
indentation found between condylar and coronoid processes
In the mandible, what is the lingula and how can it interfere with IA nerve blocks
1) tongue like small projection of bone
2) attaches the sphelomandibular ligament (this runs from sphenoid bone to mandible)
In the temporal bone, what is the mastoid process, where does it lie, give greek origin
1) attaches sternocleidomastoid muscle
2) at bottom of the bone
3) mastos is greek for breast
In the temporal bone, what is the styloid process, where does it lie
1) looks like a stylus and attaches several small muscles
2) sticks downwards
what is the petrous part of the temporal bone
part of the temple bone which has hearing apparatus and organs of balance embedded w/in it (nerves going to these organs run through it too)
‘petrous’ because it is the HARDEST part of bone in the body (rock hard)
this part of the temporal bone contributes to the base of the skull
Where does the base of the skull lie
immediately under the brain
what does the temporal bone articulate with
the (condylar process of the ramus of the) mandible at the TMJ
How does the external ear canal relate to the temporal bone
it passes through here on its way to the ear drum (tympanic membrane)
What are the TMJs
joint between the mandible and cranium where mandible articulates with cranium
most complex joints in the body
Explain TMJ disorders
TMJs are prone to disorders that can affect the effective functioning of the dentition (~40% of population have problems during life and ~4% have treatment related to disorders of these joints)
Where is the head of the mandible when the mouth is closed
in the mandibular fossa
THIS is resting position
What is the mandibular fossa
concavity / depression on undersurface of temporal bone
Where is the head of the mandible when the mouth is open
the articular eminence (bc the head of the mandible has undergone rotation and slides forward)
what is the articular eminence
projection of the temporal bone on its undersurface
what is anterior dislocation of the TMJ
where the condylar head can slide in front of the articular eminence when mouth is opened too far and cannot get it back into its normal position without help so your mouth will be stuck wide open
why are 2 people required to put the head of mandible back into resting position?
muscles attaching to mandible to pull it up during biting go into spasm when tmj is dislocated constantly trying to pull it up SO need to apply force to the mandible to move it backwards
how do you get the head of mandible back into resting position?
person 1) press down on mandibular molar teeth
person 2) slides mandible backwards
how can dislocation occur
most likely though external force (ie punch) but can be done by yawning
explain the structure of the maxillae
bears the upper teeth
it is hollow and the air-filled space inside it is called the maxillary air sinus
maxillary air space is the largest of all bones in the skull
what are the air sinuses
resonating chambers which change the nature of your voice
can fill up w mucus when you get a cold
they can get INFECTED
what is the problem with maxillary air sinus infection and how may dentists cause infection
1) can develop maxillary sinusitis
2) make communication between maxillary air sinus + oral cavity when extracting a maxillary molar allowing infection
explain the effects of maxillary sinusitis
stimulates nerves supplying upper teeth (run just deep to mucosa lining the maxillary air sinus) and the brain interprets this stimulation as pain coming from the teeth
what is the effect of maxillary sinusitis an example of
REFERRED dental PAIN
patient feels the pain originated in the teeth when its actually being caused elsewhere
pain generated at one site but perceived as arising from another is described as
REFERRED pain
which foramen lies in the maxilla (one on each side)
INFRAORBITAL foramen
what is the infraorbital foramen and where do they lie
1) transmits the end of the infraorbital nerve which supplies the upper teeth
2) under (infra) the orbits (orbital)
what is an infraorbital nerve block
anesthetising some sensory nerves supplying the upper teeth which are around this foramen
BUT need to know where the foramen is and not to push the needle in too far ie into the orbit
what would the effect of injecting anesthetic solution into the orbit
muscles moving eyeball temporarily paralysed
causing DOUBLE vision (DIPLOPIA)
what does it mean to have high cheekbones
not necessarily prominent zygomatic arches
INSTEAD its the thickness (mainly fat) of soft tissues lying superficial to the bone that determines appearance of the face (inc cheekbones)
what do zygomatic bones associate with
temple bones
what is the zygomatic arch
zygomatic process of TEMPLE BONE which sticks forward to articulate with the zygomatic bone producing an arch of bone
it is easy to fracture
which muscle runs downward passing deep to the zygomatic arch before attaching to coronoid process of the mandible
the temporalis muscle
what is a comminuted fracture
when bone is broken into 2+ / several fragments
what is the zygomatic bone and where is it located
contributes to profile of the face and to the orbit and affects configuration of soft tissues overlying it
what is the orbit
the space occupied by the eye
which bones contribute to the orbit
zygomatic, upper surface of the maxillaa and top of the sphenoid
what is the sphenoid bone, where does lie
1) complex bone likened to the shape of a butterfly and has some important muscles attached to it
also has fissures and foramina which transmit important structures
2) in base of skull just anterior to the petrous part of the temple bone
what projections does the sphenoid bone have
more superior prominent projections stick outwards
2 either side
2 greater wings
2 lesser wings
also has downward projections which connect some muscles used in chewing
the oral cavity and the mouth are…
NOT THE SAME THING
what is the oral cavity
contained within the mouth, bounded on 3 sides (anterior, right, left) by the teeth in the upper and lower dental arches
SO it cannot be seen when the teeth are occluded
what is the space inside the mouth outside of the dental arches called?
the VESTIBULE of the mouth
what does the oral cavity open into posteriorly?
the PHARYNX (connects mouth to oesophagus)
where does the vestibule of the mouth lie
between the teeth and cheeks laterally and teeth and lips anteriorly
what are sulci in the vestibule of the mouth
sulci are gutters created when mucosa lining the cheeks and lips arches over to form the roof and floor of the vestibule before reflecting onto the gingivae
there is superior sulcus AND inferior sulcus
what are buccal sulci
where vestibule is associated w the CHEEKS
there are inferior and superior versions
what are labial sulci
where vestibule is associated w the LIPS
there are inferior and superior versions
what are the buccal and labial frenula
small folds of mucosa passing between the gingivae and the cheeks/lips
what is the lingual frenulum
ligamentus like structure in the midline of the tongue (seen when its lifted up)
this limits how far up you can lift tongue from floor of mouth
what is ankyloglossia (tongue tie)
condition where lingual frenulum is abnormally short
causes reduced mobility of the tongue which can affect speech
treated by surgery
what are sublingual folds (theres right and left ones)
folds raised in floor of mouth when lift tongue
these have submandibular salivary gland DUCTS running through them
theyre raised when lift tongue up because ducts are being pulled upwards
what are the 2 distinct parts of the tongue
1) anterior 2/3 (largest)
2) posterior 1/3 (difficult to see - directed into the pharynx)
what is the SULCUS TERMINALIS
junction between the 2 parts of the tongue
its a V shaped boundary forming a groove on the tongues dorsal surface
where the 2 parts are fused together
explain the nerve supply to the tongue
both parts have different nerve supplies (consequence of their different embryological origins)
what 2 parts make up the palate
1) larger more anterior hard palate
2) most posterior soft palate (muscular, tendinous, attaches to posterior border of hard palate)
how many bones contribute to the hard palate
4 (2 on left, 2 on right)
which bones are they
most anterior 2 = part of the maxilla
most posterior 2 = part of the palatine bone
what are sutures
immobile joints where the bones of the harder palate join together
theyre ONLY found in the skull and theres lots of them
How do the right and left halves of the palate develop from being an embryo
in embryo = 2 separate structures
then = 2 sides migrate towards each other fusing in the mid-line
what happens if the process of the 2 sides of a palate fusing together goes wrong
cleft palate and/or cleft lip
in the neck, what is the hyoid bone, what bones does it articulate with
1) U shaped bone 2/3cm below the mandible suspended by muscles attaching to it
important for swallowing and speech
2) NONE
in the neck, what is the sternocleidomastoid (SCM) muscle
large muscle
starts at the CLAVICLES and STERNUM before running up and out to insert into MASTOID process of the temple bone (just behind your ears)
what hangs from the hyoid bone
the larynx (and the trachea hangs from this)
what is the relevance of the thyroid gland here
contributes to larynx’s nerve supply
imp in controlling metabolism
located below larynx and wrapped around anterior and lateral aspects of the upper trachea
what 2 large vessels lie either side of the larynx
1) common carotid arteries = main blood vessels carrying blood to head + neck, they branch
2) internal jugular veins
what does the larynx contribute to
tube like structure felt in anterior aspect of neck (between right and left sternocleidomastoid)
where may you find pulse points on the head and neck
temporal pulse
facial pulse
carotid pulse
what is the problem that could arise from pulpating the both right and left carotid pulse at the same time
there are sensors for blood pressure where common carotid divides
SO if rub on these areas hard the brain thinks blood pressure has inc’d so reduces heart rate + force of contraction to reduce pressure (makes you feel faint / pass out)
