Axial Skeleton (skull) Flashcards
What forms roof of cranial cavity?
Calvaria
What forms rostral wall of cranial cavity
Cribriform plate
What does nasal septum do?
Divides nasal cavity into two nasal fossae
What is the nasal aperture?
Rostral bony opening into nasal cavity
What are choanae?
Two bony openings at the caudal end of the hard palate and nasal septum. Lead from nasal cavity to single nasopharynx
What is a paranasal sinus?
Air filled space in facial bones of the skull (btw external and internal layers)
Name horse paranasal sinuses
Maxillary, frontal, conchal, sphenopalatine
Name biggest paranasal sinus in horse and it’s clinical significance
Maxillary
Teeth can project into it causing sinusitis and affecting the brain
Name ox paranasal sinuses
Frontal, maxillary, conchal, sphenoid and palatine, lacrimal
What is the biggest sinus in an ox
Frontal (extends into the horn in horned ruminants)
Compare maxillary sinus in an ox and a horse
Horse maxillary sinus is split into rostral and caudal parts by a bony septum
Ox only have a singular maxillary sinus
Name what is unique to dogs in mandibular ramus
There are 3 processes
1) mandibular symphysis
2) body
3) Ramus
What is present only in horse mandibles and what is its clinical significance
Vascular notch
Palpating of facial artery for pulse
Name joint that connects mandible to skull
Tembromandibular joint (TMJ)
What is the hyoid apparatus
Series of connected bones that suspend tongue and larynx from the skull in intermandibular space
How does hyoid apparatus differ in horses/ox vs carnivores?
Horses have lingual process-projection of basihyoid bone into the tongue
Ox have this as well but is shorter
Absent in carnivores
Also side of articulation differs in carnivores vs horse/ox
Epihyoid is small in equine
What is zygomatic arch and its clinical significance?
Arch of bone projecting lateral from the skull (widest part of skull)
Forms bridge btw facial and neurocranial regions
Clinically palpable structure
What bones form the zygomatic arch
Zygomatic process of the:
Zygomatic bone
Temporal bone
Maxilla bone
Frontal bone
Why is facial crest (found only in horses) clinically significant
Landmark for maxillary sinus (ventral boundary clinically)
Also can use to find infraorbituve nerve with nasoincisive notch
Ruminants have ___ instead of facial crest
Facial tuberosity
What is the orbit?
Funnel shaped region that houses the eye
How does orbital rim differ btw species
Carnivores - incomplete (orbital ligament closes caudal side)
Horses/ruminants- complete
What is the pterygopalatine fossa?
Depression caudoventral and continuous to the orbit (perioribita fascia separates it in real life) and medial to zygomatic arch/ ramus of mandible. Contains many foramina for vessels and nerves, filled by the pterygoid muscles
What is the external acoustic meatus?
Osseous opening to the ear and opening to tympanic bulla
Closed by tympanic membrane (eardrum)
It’s borders give the attachment for cartilage of the ear canal
Where/What is the mastoid process?
Caudodors to extern acoustic meatud
Attachment site for muscles ( and hyoid process in dogs)
Where/What is cornual process?
Occurs only in horned ruminants
Continuation of frontal bone caudally
Supports the hint and houses cornual diverticulum of frontal sinus
What is external Sagittal crest?
Median crest along caudal skull in dogs/horses (absent in ruminants)
Varies with age breed and sex (prominent in males)
What is temporal line?
Form rostromedial boundaries of temporal fossae (which houses massive temporal is muscle)
They converge to form external sagittal crest
How does temporal line in ox differ? And describe its clinical significance
Pushed laterally by frontal bone
Extends btw caudal orbit and caudal skull
Is dorsal to cornual VAN (dehorning location for injection)
What is the hard palate
3 bones to form roof of the oral cavity
Departed oral an nasal cavities
What is the tympanic bulla and its clinical significance
Bony vesicle (bubble) that houses the middle ear
May vs entered to drain otitis media in carnivores
How does cat tympanic bulla differ?
Has septum bulle (dived bulla into 2 unequal compartments)
Needs to be broken carefully (to prevent sympathetic nerve damage )in order to permit drainage
How do horse/ox tympanic bulla differ?
Reduced in size compared to carnivores
Where/What is the nuchal crest
Transverse ridge at transition from dorsal to caudal surface of the skull (extend laterally from each side of external occipital protuberance)
Where is the external occipital protuberance and what is its clinical significance?
It is the most caudodorsal extent of skull
Palpable landmark for CSF taps in dogs (tap in middle of triangle formed by this and wings of atlas)
What is the infraorbital foramen and its clinical significance
Rostral opening to infraorbital canal
Location for dental nerve block
Name/describe fibrous joints of the skull
Sutures (only present btw bones in fetus and young animals)
Fontanelles (at points where more than 2 bones meet)
Gomphosis (implant teeth in alveoli by periodontal ligaments, do not ossify with age, only joint type btw bone and non-bone aka teeth)
Name the fibrocartilaginous joints of skull
Mandibular symphysis
Name the Cartilaginous joints of skull
Joint of hyoid apparatus and skull
Name the Synovial joints of skull
Hyoid apparatus and larynx join
TMJ aka tempromandibular joint
Atlanto-occipital articulation
What is another name for the facial region
Visceral or viscerocranium
What is another name for the neural region
Neurocranium
What are the unpaired bones of the skull
Vomer, ethmoid, occipital, basihyoid
Where does the hyoid apparatus articulate in carnivores
Mastoid process
4) Basihyoid
5) Ceratohyoid
6) thyrohyoid
7) Epihyoid
8) Stylohyoid
9) Tympanohyoid
What lies in masseteric fossa
Masseter m.
Describe the mandibular canal
Rostral end = mental foramina
Caudal end = mandibular foramen
inferior alveolar VAN runs here
Note: inferior alveolar n joins lingual nerve outside mandibular foramen to form mandibular n
Clin sig of condylar process
Location for TMJ
Clin sig angular process
pterygoid muscles attach here
1) Coronoid process
2) Masseteric fossa
3) mandibular foramen
4) condylar process
5) angular process
6) mental foramina
7) myelohyoid line
8) mandibular canal
9) mandibulr symphysis
10) Body of mandible
11) Ramus
Clin sig of coronoid process
Highest one - “the crown”
Insertion of temporalis m
May become trapped outside of zygomatic arch in lock jaw syndrome
species differences of mandibular symphysis
Completely ossifies in horse
Remains fibrocartilaginous in dog (not considered a fracture if it breaks)
Name each bone and what they do
1) Nasal - forms smallest part of nasal cavity
2) incisive - house upper teeth
3) maxilla - house canine and upper cheek teeth
4) Lacrimal - has “fossa/cave” for lacrimal sac (do not confuse for a foramen)
Name each bone and what they do
10) Zygomatic - forms PART of zygomatic arch
11) Palatine - forms small part of hard palate. Also part of lateral, ventral skull
12) Pterygoid which has 13) hamulus (hook)
What is the sphenoid complex
Caudal part of pterygopalatine fossa
houses several foramina (caudal group)
forms part of skull floo
What is this?
Pterygopalatine fossa
Sphenoid complex
Name each bone and what they do
Blue) Parietal bone - form caudolateral parts of calvarium
Red) Frontal - form rostra part of cranial vault
Yellow) Zygomatic process of frontal bone
Black) Frontal process of zygomatic bone
9) Temporal Bone
Name and describe bone
Petrous part of temporal bone - completely within the skull (only its mastoid process seen externally)
Very dense bone housing the inner each and where CN 7 and 8 (vestibulocochlear, facial) enter
Name and describe bone
1) Tympanic part of temporal bone - houses middle ear, Tympanic bulla/cavity (may be entered for drainage in otitis media), external acoustic meatus, ossicles of middle ear
2) Mastoid process - only part of petrous bone to be seen externally
3) External acoustic meatus
Name and describe bone
a) squamos part of temporal bone - ventral part of lateral wall of cranium
b) zygomatic process (caudal 1/2 of zyg. arch)
c) Termporal part of TMJ - has mandibular fossa (where condylar process articulates) and retroarticular process
1) occipital condyles
2) Foramen magnum
3) External sagittal crest
4) nuchal crest
5) External occipital protuberance
1) External sagittal crest
2) Temporal line
3) Temporal fossa
What lies in temporal fossa
Massive temporalis m.
What composes the ethmoid complex
Ethmoturbinates
cribriform plate - separates cranial and nasal cavities, has holes got passage of olfactory nerves and blood vessels
What is the crista galli
continuation of ethmoid bone (perpendicular plate of ethmoid aka bony nasal septum) that forms vertical separation of cribriform plate
1) Ethmoturbinates
2) Cribiform plate
Name structures. What structure runs though #2
1) Infraorbital foramen
2) infraorbital canal - where infraorbital VAN runs
3) maxillary foramen
1) Ethmoid foramina
2) Fossa for lacrimal sac
3) Infraorbital foramen
4) Sphenopalatine foramen
5) Caudal palatine foramen
6) Optic canal
7) Orbital fissure
8) Rostral opening of pterygoid canal
9) Rostral alar foramen
10) Caudal alar foramen
1) Ethmoid
2) Optic canal
3) Orbital fissure
4) Rostral alar foramen
5) Caudal alar foramen
6) Oval foramen
7) Alar canal
1) Ethmoid
2) Optic canal
3) Orbital fissure
4) Rostral alar foramen
5) Caudal alar foramen
6) Oval foramen
2) Optic canal
3) Orbital fissure
4) Round foramen
6) Oval foramen
1) Maxillary foramen
2) Infraorbital canal
3) Infraorbital foramen
1) Maxillar foramen
2) Sphenopalatine foramen
3) Caudal palatine foramen
4) fossa for lacrimal sac
Name and describe nerves in this region
1) Palatine fissures
2) Major palatine foramen
3) Maxillary n (gives rise to major palatine n here)
4) Palatine canal ( major palatine n enters through the caudl palatine foramen and exits the major palatine foramen)
1) Major palatine n
2) Caudal palatine foramen
3) Sphenopalatine foramen
Stylomastoid foramen - between tymopanic bulla and mastoid process
1) Tympano-occipital fissure
2) Hypoglossal canal
3) Foramen magnum
1) Nasal aperture
2) Vomer - nasal septum lies in its groove
What defines the boundaries of the nasal fossa
runs from nasal aperture to choanae
What defines the boundaries of the cranial vault
Rostral - cribriform plate
roof - frontal and parietal bones
floor - sphenoid complex, temporal, and occipital
caudal wall - occipital bone
lateral wall - frontal and parietal bones and part of temporal
Name and describe
1) Rostral fossa - (1/5 of cranial cavity) from cribriform plate to optic canal, houses olfactory bulbs and frontal lobes
2) Middle cranial fossa - (3/5 of cranial cavity) from end of cranial fossa to middle of petrous part of temporal bone
3) caudal cranial fossa - (1/5 of cranial cavity) where osseous tentorium cerebelli is
Describe the tentorium cerebelli
shelf of bone separating cerebrum from cerebellum
clin sig is cerebral herniation if ICP is increased
How does cat skull differ
No alar canal
septum in tympanic bulla
Larger tympanic bulla
Smaller and rounder skull, fewer teeth, bigger orbits
1) external occipital protuberance
2) nuchal crest
3) occipital condyle
4) paracondylar process (note: present in all species)
1) Nasoincisive notch
2) infraorbital foramen
3) supraorbital process and foramen
4) Zygomatic arch
5) Orbital fossa
6) Lingual process of hyoid bone (absent in carnivores, short in ox)
7) Vascular notch - where to take pulse
black dashed line) facial crest
Describe hyoid process in horse
Has large lingual process
Attached to styloid process
clin sig: temporohyoid osteoarthropathy
How do ruminant skulls differ
no upper incisors
Facial tuberosity
large frontal bone (parietal and temporal pushed katerally)
Lacrimal bulla (caudal extension of the maxillary sinus - protrudes into orbit)
Foramen orbitorotundum (orbital fissure + round foramen)
Ptyerygoid crest (project lateral to the foramen orbitorotundum)
What is a peterson retrobulbar block
for enucleation of the eye
placed in angle btw frontal and temporal process of the sygomatic bone rostral to F. orbitorotundum
avoid lacrimal bulla and coronoid process
1) optic canal
2) foramen orbitorotundum
3) lacrimal bulla
4) zygomatic arch
5) pterygoid crest
What is the foramen lacerum
Large foramen in horse
fusion of oval and tympano-occipital fissure
What is this?
Foramen lacerum
star/1) Frontal sinus
2) Sphenoid sinus - only in cats
