module 4 Flashcards
The human skull can be
divided into two parts.
neurocranium and viscerocranium
neurocranium bones
8 bones
Unpaired
* Ethmoid
* Sphenoid
* Frontal
* Occipital
-occiput
Paired
* Parietal
* temporal
process meaning
something that sticks out
suture meaning
fixed immobile joints
Sphenoid bone structures
Lesser wings
*Top of the optic canal
Greater wings
* part of orbit
* Articulate with frontal
and temporal bones
Pterygoid processes
* Project inferiorly from
greater wing and corpus
* Two plates: medial and
lateral
—
Sella Turcica- In between the two lesser wings: a depression called the Sella Turcica (also: hypophyseal fossa)
* Location of the pituitary gland (hypophysis)
sphenoid bone functions n foramen
Function:
* Part of the base and lateral sides of the skull
* Gives the skull rigidity
* Has several foramen and fissures that allow nerves and blood vessels to enter and exit the cranial cavity
* Optic canal: optic nerve
* Foramen ovale (oval): trigeminal nerve (mandibular branch)
* Foramen rotundum (round): trigeminal nerve (maxillary branch)
* Forman allow nerve to penetrate bony shelf to get to face
* Attachment site for muscles of mastication and swallowing
ethmoid bone anatomy
- Forms:
- Medial part of orbit ( sphenoid is lateral)
- Projects superiorly into anterior cranial fossa (bony shelf brain rests on)
- Projects Inferiorly into nasal
cavities
Crista galli
* Superior projection
* protrudes into cranial cavity
Perpendicular plate
* Superior part of the nasal septum
Middle and superior nasal conchae
Mandible
‘mental’ = chin
The only moveable bone of the skull, fuses during first year after birth
* Mental symphysis and protuberance (superman chin)
* Alveolar process
* Lingula - Bone projections/Landmark to locate the mandibular foramen
* Mental and Mandibular foramen - Passage way for the mental nerve (part of the mandibular branch of the trigeminal nerve)
Ramus
* Angle of approximately 90 degrees
* Attachment for the masseter muscle and the
medial pterygoid muscle (to be discussed
Coronoid process
* Anterior side of the ramus
* Attachment for the temporalis muscle
(mastication – see later)
Condylar process:
* Posterior and superior part of the ramus
* The head (condyle) is part of the temporomandibular joint (TMJ)
—* Important for rotation of the mandible
In between the coronoid process and the condylar process: mandibular notch
Maxillary bones – anterior view
- Upper jaw
- Landmarks
- Frontal process
- Infraorbital foramen (III
- maxillary)
- Zygomatic process
- Nasal spine and notch
- Alveolar ridge
Maxillary bone: medial view
Medial view:
* Maxillary sinus
* Palatine process
* Alveolar ridge (process)
Maxillary bone: inferior view
Inferior view:
* Bilateral palatine process
* Intermaxillary suture (cleft
palate)
* Transverse palatine suture
* Premaxilla (cleft lip)
Palatine bone
- Small, L-shaped bones
- Horizontal plate: posterior one-fourth of
the hard palate - Perpendicular plate, nasal crest
- Lateral wall and floor of nasal cavity
- Posterior wall of orbit
Nasal conchae
- Superior and middle conchae are part of the ethmoid bone
- Inferior nasal conchae is an independent bone
- In between the conchae: meatuses (superior, middle and inferior)
- Mucosal lining is thick with rich vascular
supply - Important function in warming, humidifying
and cleaning incoming air
Vomer
- unpaired midline bone
- Divides the nasal cavity
- Forms the inferior and
posterior part of the
nasal septum (which can
be deviated) - Early in development:
cartilage (process starts
in fetal stage but may
continue until puberty)
Complete nasal septum
consists of:
* Vomer
* Perpendicular plate of the
ethmoid bone (see later)
* Septal cartilage
Connection to the sphenoid
bone, palatine bone and
maxillary bone
Zygomatic bone
- Known as the cheekbone
- Laterally: temporal process
connects to the zygomatic
process of the temporal bone
to form the zygomatic arch - A: frontal process (frontal bone
and sphenoid bone) - B: maxillary process (meets the
maxillary bone) - C: temporal process (anterior
half of the zygomatic arch)
Hyoid bone
- Floating - not connected to any other
bones, only tendons (e.g., thyrohyoid) - Serves as anchor point for artic and
swallowing muscles (e.g., geniohyoid) - Vallecula: depression where hyoid bone,
tongue and epiglottis meet - Important landmark for intubation
Teeth
- Housed in the alveoli (little hollows) of the mandible and maxilla
- During development: two sets of teeth
—* Primary: 20 teeth
—* Permanent: 32 teeth - Occlusal surface – biting surface
- Lingual surface – toward tongue
- Labial surface – toward lips
- Buccal surface – toward cheeks
- Approximal surfaces: toward adjacent teeth (between teeth, where the floss goes)
teeth types
Incisors (cutting - 4 on top and bottom)
* Erupt around 6 months of age
* Replaced between 6-8 years of age
Canines (cuspid - tearing) (2 on top and bottom)
* Erupt between 16-20 months of age
* Replaced between 9-12 years of age
Premolars (bicuspid) (2x4)
* No primary
* Erupt around 10-11 years of age
Molars (2x6)
* First two: primary around 12-15 months; permanent around age 6 years
* Next two: permanent around 11-13 years of age
* Third molar (wisdom teeth): erupt between 18-20 years of age (or not at all)
Teeth alignment
Class I occlusion
* normal position
Class II occlusion (buck teeth)
* increased overjet (overbite)
* Receding chin
* Most common (45%)
Class III occlusion
* Underbite
* Protruding jaw
* (sometimes in Down syndrome)
vocal tract cavities
Nasal cavity
Oral cavity
Pharyngeal cavity
* Nasopharynx
* Oropharynx
* Laryngopharynx
articulation mobile and immobile structures
- Mobile structures (lips, tongue,
velum, mandible, pharynx) - Immobile structures (teeth, alveolar
ridge, hard palate)
Pharyngeal cavity
From the base of the skull superiorly
to the superior (some texts: the
inferior) border of the cricoid
cartilage of the larynx
Nasal cavity
Anteriorly from the tip of the nose (nostrils) posteriorly to the nasal choana (division between nasal cavity and nasal pharynx)
* Velopharyngeal port: division between nasopharynx and oropharynx
Oral cavity
- Anteriorly from the lips to posteriorly the palatoglossal arches
- Epiglottis – at the base of the tongue: division between oropharynx and laryngopharynx
Laryngeal cavity
Superiorly from the epiglottis, inferiorly to the cricoid cartilage
categories of head muscles
4 categories
- Muscles of facial
expression - Muscles of the tongue
- Muscles of the velum
- Muscles of
jaw/mastication
facial expression muscles divisions
They can be divided into
1. muscles that pull the
mouth up - Elevators
2. muscles that pull the
mouth down - Depressors
3. “other”.
modiolous
If you look at the origin of the facial muscles you will see that many of them attach to the corner of the mouth.
There is a small circle of connective tissue to which the muscles all attach. It is called the “modiolus” this means the hub/center of a wheel.
“Other” Facial Muscles
The orbicularis oris, risorius and buccinator are the “other” muscles of facial expression because they do not clearly fit in the elevator or depressor
category
Orbicularis Oris
means “ring-like” and
“mouth”. You can think of it like an
‘orbit’ around your mouth.
Form and shape of lips and maybe movement
Risorius
means “scoffer” (someone who scoffs or laughs at ridiculous things). This muscle pulls the corner of the mouth laterally like a grin or
smile.
Buccinator (Bux)
means “bugler’s muscle”.
This is a muscle of the cheek that keeps the cheeks firm for blowing, sucking, and keeping food in the oral cavity during
chewing.
elevating Facial Muscles
levator labii superioris means “lifts the lips above”.
levator anguli oris means “lifts
the angle of the mouth”
“Depressing” Facial Muscles
Mentalis muscle - raise the skin of the chin and elevate, evert (turn outward), and protrude the lower lip. facial expression of doubt and contempt. nicknamed the “pouting muscle”.
Platysma muscle
sets on tonsils
Palatine Tonsils – Lateral surface of the oropharynx
Adenoids – Lateral surface of the nasopharynx
Lingual Tonsils – Pharyngeal surface of the tongue
tongue how much is where
2/3 in oral cavity
* 1/3 in the oropharynx
tongue structures/landmarks superior
Landmarks: superior
surface
* Apex (tip)
* Body
* Dorsum
* Median sulcus
* Foramen cecum
* Papilla (pah-PILL-ah)
landmarks of tongue inferior
Lingual frenulum- tongue tied when frenulum is too short
landmarks of tongue pharyngeal
Lingual tonsils
Hydrostat
- In a muscular hydrostat, the
musculature itself both creates
movement and provides
skeletal support for that
movement. - It can provide this support
because it is composed
primarily of an incompressible
“liquid” and is thus constant in
volume (fluid filled container). - Other examples of hydrostat
are octopus tentacles and
elephant trunks.
Muscles of the Tongue
The tongue muscles are paired, each with a right and left component.
Each half is controlled by the contralateral half of primary motor cortex through
corticobulbar tract/hypoglossal cranial nerve
Tongue muscles can be categorized into intrinsic and extrinsic muscles.
Intrinsic muscles tend to be for fine control for articulation.
Extrinsic muscles are for general movements involved in mastication and
deglutition.
When one side of tongue is paralyzed/weak, the tongue will push toward the
weak side upon protrusion.
Intrinsic muscles of the tongue
- Superior longitudinal
- Inferior longitudinal
- Transverse
- Vertical
Extrinsic muscles of the tongue
- Genioglossus
- Hyoglossus
- Styloglossus
- Chondroglossus
- Palatoglossus
velum
- The velum is also called the soft palate.
- It extends posteriorly from the hard palate.
- If you run your tongue along the roof of your mouth from front to back you will
feel a bump and then the squishy stretchy surface of the “tent” that is your soft
palate. - It has no bones or cartilage in it.
- For the large majority of speaking time you are holding the palate up by
contracting soft palate muscles. - It has 2 elevators, 2 depressors and a eustachian tube opener.
Palatal Aponeurosis
Most of the muscles of the velum have their insertion or origin on the palatal
aponeurosis.
aponeurosis is a sheet-like tendon. A tendon always
connects muscle to something (bone or cartilage) because it is actually a part/extension of the muscle.
The palatal aponeurosis is part of the levator veli palatini muscle and runs along the
middle of the velum where muscles of the right and left velum fuse together.
All the muscles of the velum are paired muscles, each with a right and left
component. Often only one side is paralyzed (uvula will tilt toward strong side)
Elevators of the Velum
Levator veli
palatini and Mucularis Uvulae
Velopharyngeal
Depressors
Open the velopharyngeal port
for nasal sounds, lowers it
toward the tongue or pharynx
and narrows pharynx for
swallowing.
* Palatoglossus
* Palatopharyngeus
