Transcript Skeletal Terms  Foramen / Fenestra = opening; hole.  Fossa = depression; indentation.  Process = prominence (bump).  Protuberance = prominence (bump). 

Skeletal Terms
 Foramen / Fenestra = opening; hole.
 Fossa = depression; indentation.
 Process = prominence (bump).
 Protuberance = prominence (bump).
 Tuberosity = prominence (bump).
 Crest = raised ridge.
 Condyle = part that articulates with
another element.
 Suture = visible line indicating where
Skeletal Terms
 Foramen / Fenestra = opening; hole.
 Fossa = depression; indentation.
 Process = prominence (bump).
 Protuberance = prominence (bump).
 Tuberosity = prominence (bump).
 Spine = prominence (bump).
 Crest = raised ridge.
Types of Bone
 Endochondral = bone replaces a
cartilage precursor.
Intramembranous bone
 Dermal = bone forms in the connective
tissue of the dermis.
 Sesamoid = bone forms in the
connective tissue of a ligament.
 Perichondral / Periosteal bone =
bone forms in connective tissue
surrounding cartilage or bone.
Endochondral Bone Growth
Intramembranous Bone Growth
The Skeleton
 Endoskeleton = forms within the
body from mesoderm and sometimes
neural crest (deep to the integument);
bone or cartilage
 Exoskeleton = forms within the
integument from mesoderm and
mesoderm & neural crest (dermal
bony scales, dermal bone); bone
Human Skull Bones
 Nasals
 Frontal
 Parietals
 Maxillas
 Mandible
(Dentaries)
 Lacrimals
 Zygomatics
(Jugal)
 Vomer
 Palatines
 Ethmoid
 Sphenoid
 Temporals
 Occipital
 Malleus, Incus,
Stapes
 Hyoid
Human Skull
sphenoid
nasal
frontal
parietal
temporal
lacrimal
maxilla
(includes
premaxilla)
occipital
zygomatic
(jugal)
mandible (dentary)
Human Skull Stutures
saggital suture
coronal
suture
squamosal
suture
lamboidal
suture
Human Skull-Temporal Bone
mandibular
fossa of
temporal
(condylar
process of
mandible)
Ethmoid
middle ear bones
in here
Human Middle Ear
Human Skull-Mandible
coronoid
process
mandibular
foramen
mental
foramen
chin
(mental process)
condylar
process
mandibular
notch
masseteric
fossa
angle of
mandible
(angular process)
Human Skull
hyoid
bone
Three Parts of the Cranium
 Chondrocranium = cartilage or
endochondral bone, underlies (or
surrounds) the brain. (endoskeleton)
 Splanchnocranium = cartilage or
endochondral bone, “jaw” and gill arch
skeleton. (endoskeleton)
 Dermatocranium = ossification of
connective tissue in dermis, superficial
to rest of cranium. (exoskeleton)
Osteichthyan Skull
Chondrocranium Development
 Develop from neural crest & mesodermal mesenchyme.
Nasal capsule
(Olfactory capsule)
Ethmoid Plate
Trabecular Cart.
Optic capsule
Trabecular Plate
(Sphenoidal Plate)
Basal Plate
Otic capsule
Parachordal Cart.
Occipital Cart.
Chondrocranium Regions
 Ethmoid – between nasal/olfactory capsules,
“nose” region
 Sphenoid – underlies brain, “eye” region and
posteriorly
 Otic - otic capsules, “ear” region
 Occipital - around the foramen magnum
human
cranial cavity
superior view
(chondrocranium
shaded)
Splanchnocranium Development
 Splanchnocranium from neural crest.
Dermatocranium Development
 Dermatocranium from mesenchyme cells of
the dermis, primarily mesoderm.
Dematocranium
 Nasals
 Frontal
 Parietals
 Maxillas
 Mandible/Dentaries
 Lacrimals
 Zygomatics/Jugals
 Vomer
 Palatines
 Pterygoid proc. of Sphenoids
 Squamous & Zygomatic

parts of Temporals
Postparietal/Interparietal
portion of Occipital
Chondrocranium
 Ethmoid
 Central part of Sphenoid
 Petrosal (Otic) portion of

Temporal
Supraoccipital, Exoccipitals
and Basioccipital of
Occipital
Splanchnocranium
 Greater wing of Sphenoid
 Styloid process of Temporal
 Malleus, incus, & Stapes
 Hyoid
 Thyroid, Cricoid, and
Arytenoid cartilages
Human Compound Bones
 Maxillas = maxillas + premaxillas
 Palatines = dermopalatines + autopalatines
 Temporal bones = squamosals + prootics +
opisthotics (petrosals) + styloid processes
 Occipital bone = supraoccipital +
basioccipital + exoccipitals + fused post parietals
(interparietal)
 Sphenoid bone = basisphenoid +
presphenoid + orbitosphenoid + alisphenoid +
pterygoids
Human Chondrocranium
Human Splanchnocranium
Human Skull Development
Human Skull Development
fontanelle
right
frontal
left
frontal
sphenoid
nasal
maxilla
(includes
premaxilla)
right
frontal
Human Secondary Palate
 Palatal shelves form it (maxillas & palatines);
separates nasal & oral cavities
 Cleft palate = when fusion of the
secondary palate does not occur.
 Cleft lip = when fusion of the maxillas
(maxilla & premaxilla) doesn’t occur.
Chondrocranium
 Does not cover brain dorsally…
except in Chondrichthyans.
 Single cartilaginous unit in
Chondrichthys, Petromyzontida, and
Myxini.
Osteichthyan Chondrocranium
ethmoid
sphenoid
otic
occipital
Canis (dog) Skull
Splanchnocranium
 Pharyngeal arch supports.
 Hagfishes & Lampreys = ONLY
involved in gill arch support.
 Gnathostomes = anterior
splanchnocranium forms jaws & jaw
supports.
 Gnathostome jaws are serially
homologous with gill arch supports.
Jawless Vertebrate
cranium
mouth
pharyngeal openings
Jawless Vertebrate
mouth
pharyngeal openings
Jawed Vertebrate
spiracle
upper
jaw
mouth
lower
jaw
pharyngeal openings
Splanchnocranium
 Palatoquadrate = upper jaw (arch #1
epibranchial)
 Meckel’s Cartilage = lower jaw (arch
#1 ceratobranchial)
 Hyomandibula = upper jaw support
(arch #2 epibranchial)
 Hyoid = tongue and lower jaw muscle
attachment (arch #2 ceratobranchial)
Squalus Skull
Chondrocranium
Palatoquadrate
Hyomandibula
Meckel’s
cartilage
Squalus Head Skeleton
hyomandibula
Chondrocranium
palatoquadrate
Meckel’s
cartilage
ventral hyoid elements
Osteichthyan Splachnocranium
 Palatoquadrate – ossifies as
autopalatine, epipterygoid (alisphenoid or
greater wing of sphenoid), & quadrate (incus)
 Meckel’s cartilage - posterior ossifies
as articular (malleus)
 Hyomandibula ossifies (stapes, columella)
autopalatine
epiquadrate
pterygoid
hyomandibula
palatoquadrate
Meckel’s cartilage
articular
Osteichthyan
Splanchnocranium
autopalatine
quadrate
hyomandibula
articular
Jaw Elements
 In non-mammalian gnathostomes the jaw
joint is between the splanchnocranial
quadrate (upper jaw) and articular (lower jaw).
 In all osteichthyans teeth (if present) are
borne on dermatocranial bones,
premaxilla & maxilla (upper jaw)
dentary (lower jaw)
 In mammals the jaw joint is between the
dermatocranial squamosal (upper jaw) and
dentary (lower jaw).
Dinosaur/Tetrapod “Jaws”
quadratearticular
joint
maxilla
pmx
surangular
angular
dentary
Subphylum Vertebrata
dorsal
chondrocranium
Dermatocranium
(Osteichthys)
Jaws (Gnathostomata)
palatoquadrate, Meckel’s cart.
Chondrocranium, Splanchnocranium
Dermatocranium
 Only Osteichthys. Superficial.
 Ancestrally many bones.
 Number of bones reduced in many
groups.
Bowfin, Amia calva, Skull
Teleost Upper Jaws
mobile maxilla
mobile maxilla
& premaxilla
quadratojugal
Tetrapod Skull
prefrontal frontal
postparietal
post- parietal
frontal
nasal
postorbital
lacrimal
pmx
squamosal
jugal
(zygomatic)
maxilla
dentary
surangular
angular
italic underlined = absent in any form in human
Alligator Skull
parietal frontal
Sq
QJ
an sur
PO
PrF
J
L
dent
nasals
mx
pmx
Palatal Series
vomer
palatines
pterygoids
parasphenoid
Amniote Orbital Series
Group
Prefrontal
Lacrimal
Jugal
Postorbital
Postfrontal
turtles
present
absent
present
present
absent
lizards & snakes
present
present
present
present
present
birds
present
absent
present
absent
absent
crocodylians
present
present
present
present
absent
mammals
absent
present
present
absent
absent
prefrontal
lacrimal
postfrontal
postorbital
jugal
Amniote Temporal Series
Squamosal
Quadratojugal
turtles
present
present
lizards & snakes
present
present in tuataras
Group
(absent in all others)
birds
present
present
crocodylians
present
present
mammals
Present
absent
(squamous part of
temporal)
squamosal
quadratojugal
Subphylum Vertebrata
*surangular
lost
*
mobile
maxilla
premaxilla, maxilla, dentary,
angular, surangular
(Osteichthys)
jaws
palatoquadrate, Meckel’s cartilage,
hyomandibula (Gnathostomata)
Subphylum Vertebrata
*quadratojugal
lost
*
operc. lost
(Tetrapoda)
frontals, squamosal,
quadratojugal
nasal, parietal, postparietal, 4
opercular bones, vomer,
dermopalatine, pterygoid
(Osteichthys)
Subphylum Vertebrata
*postorb., prefr.,
& postfr. lost
*
jugal,
postorbital,
prefrontal,
postfrontal
(Tetrapoda)
lacrimal, undifferentiated
infraorbitals (Osteichthys)
Amniote Skull Openings
 Space for muscle passage or flexure.
 No skull fenestras – turtles
 One skull fenestra bounded by postorbital,
jugal, squamosal – mammals
 Two skull fenestras
one bounded by postorbital, parietal, squamosal
one bounded by postorbital, jugal, squamosal
lizards & snakes and archosaurs (modified in most)
Amniote Skull Openings
no openings
1 opening
2 openings
Amniote Skull Openings
no openings
(turtles)
1 opening
1 opening
(mammals)
Amniote Skull Openings
1 opening
2
openings
mandibular &
antorbital
fenestras
Nares
 Actinopterygiian nares
Water flows in anterior naris, over
olfactory epithelium, & out posterior
naris.
Nares
 Tetrapod nares
Air enters external naris flows over
olfactory epithelium and exits into oral
cavity through internal naris (choana).
Human Nasolacrimal Duct
The Tetrapod Middle Ear
 Tetrapod upper jaw fused to skull.
 Hyomandibula not supporting jaws.
 Stapes = tetrapod hyomandibula;
small, slender middle ear bone,
conducts sound to otic capsule
Stapes/Columella
inner
ear
Subphylum Vertebrata
*secondary palate
*
**
internal nares;
stapes (modified
hyomandibula)
(Tetrapoda)
**secondary palate in crocodilians
& many turtles
Mammalian Compound Bones
 Palatines = dermopalatines + autopalatines
 Temporal bones = squamosals + otic
bones + styloid processes (in some the styloid
processes are separate)
 Occipital bone = supraoccipital +
basioccipital + exoccipitals + fused post
parietals (interparietal) (in many the
interparietal is separate)
 Sphenoid bone = sphenoid bones (in some
sep.) + alisphenoid (epipterygoid) +
pterygoids (in some the pterygoids are sep.)
Mammalian Skull
 Secondary Palate (2º palate) =
Premaxilla, maxilla, & dermopalatines
separate nasal and oral cavities.
 Temporo-mandibular jaw joint
New jaw articulation dentary/squamosal.
Tympanic annulus, Malleus, & Incus
Angular,
articular, and quadrate
become middle ear bones.
Jaws & Jaw Joint
Palatoquadrate
Hyomandibula
quadrate
articular
Meckel’s cartilage
Meckel’s cartilage
Jaws & Jaw Joint
squamosal
pmx maxila
jugal
stapes
quadrate
articular
dentary
angular
Non-mammalian tetrapods
Jaws & Jaw Joint
squamosal
pmx maxila
jugal
stapes
quadrate
articular
dentary
angular
Fossil mammal-like “reptile”
Jaws & Jaw Joint
squamosal
pmx maxila
jugal
stapes
quadrate
articular
dentary
angular
Jaws & Jaw Joint
squamosal
pmx maxila
jugal
dentary
mammal
stapes
incus
malleus
tympanic
annulus
Jaws & Jaw Joint
squamosal
pmx maxila
jugal
tympanic
bulla
dentary
mammal
Jaw Articulation
Human Middle Ear
Amniota
temporal bone,
sphenoid bone,
occipital bone,
“new” jaw joint,
incus & malleus,
2ary palate