Skeletal TermsForamen / 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 two bones abut or fuse.

Skeletal TermsForamen / Fenestra = opening; hole.

Fossa = depression; indentation.

Process = prominence (bump).

Protuberance = prominence (bump).

Tuberosity = prominence (bump).

Spine = prominence (bump).

Crest = raised ridge.

Types of BoneEndochondral = bone replaces a

cartilage precursor.Intramembranous boneDermal = 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 BonesNasals

Frontal

Parietals

Maxillas

Mandible (Dentaries)

Lacrimals

Zygomatics (Jugal)

Vomer

Palatines

Ethmoid

Sphenoid

Temporals

Occipital

Malleus, Incus, Stapes

Hyoid

Human Skull

mandible (dentary)

lacrimal

zygomatic(jugal)

nasal

maxilla(includes

premaxilla)

frontalparietal

temporal

occipital

sphenoid

Human Skull Stutures

coronal suture

saggital suture

squamosalsuture

lamboidalsuture

Human Skull-Temporal Bone

Ethmoid

middle ear bonesin here

mandibularfossa oftemporal(condylarprocess ofmandible)

Human Middle Ear

Human Skull-Mandiblecoronoidprocess

condylarprocess

massetericfossa

mandibularnotch

angle ofmandible

(angular process)

chin(mental process)

mentalforamen

mandibularforamen

Human Skull

hyoidbone

Three Parts of the CraniumChondrocranium = 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

Nasal capsule(Olfactory capsule)

Optic capsule

Otic capsuleParachordal Cart.

Occipital Cart.

Trabecular Cart.

Ethmoid Plate

Basal Plate

Trabecular Plate(Sphenoidal Plate)

Develop from neural crest & mesodermal mesenchyme.

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

humancranial cavitysuperior view(chondrocraniumshaded)

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 BonesMaxillas = 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

nasal

rightfrontal

maxilla(includes

premaxilla)

sphenoid

leftfrontal

rightfrontal

fontanelle

Human Secondary PalatePalatal 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.

ChondrocraniumDoes not cover brain dorsally…

except in Chondrichthyans.

Single cartilaginous unit in Chondrichthys, Petromyzontida, and Myxini.

ethmoid sphenoid otic occipital

Osteichthyan Chondrocranium

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

mouth

pharyngeal openings

cranium

Jawless Vertebrate

mouth

pharyngeal openings

Jawed Vertebrate

mouth

upperjaw

pharyngeal openings

lowerjaw

spiracle

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

PalatoquadrateMeckel’scartilage

Hyomandibula

Squalus Head Skeleton

Chondrocranium

palato-quadrate

Meckel’scartilage

hyomandibula

ventral hyoid elements

Osteichthyan SplachnocraniumPalatoquadrate – ossifies as

autopalatine, epipterygoid (alisphenoid or

greater wing of sphenoid), & quadrate (incus) Meckel’s cartilage - posterior ossifies

as articular (malleus)

Hyomandibula ossifies (stapes, columella)

hyomandibula

Meckel’s cartilage

palatoquadratehyomandibula

articular

auto-palatine

epi-pterygoid

quadrate

Osteichthyan Splanchnocranium

auto-palatine

quadrate hyo-mandibula

articular

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).

Jaw Elements

Dinosaur/Tetrapod “Jaws”

angular

dentary

surangular

quadrate-articularjoint

pmxmaxilla

Subphylum Vertebrata

hagfis

hes

lam

preys

Chondrichth

ys

Actin

optery

gii

coel

acan

ths

lungfis

hes

amphib

ians

Mam

mal

ia

Reptil

ia

Dermatocranium (Osteichthys)

Chondrocranium, Splanchnocranium

Jaws (Gnathostomata)

palatoquadrate, Meckel’s cart.

dorsalchondro-cranium

Only Osteichthys. Superficial.

Ancestrally many bones.

Number of bones reduced in many groups.

Dermatocranium

Bowfin, Amia calva, Skull

Teleost Upper Jaws

mobile maxilla mobile maxilla & premaxilla

Tetrapod Skull

frontalparietal

post-parietal

nasal

quadratojugal

squamosal

maxillapmx

lacrimal

jugal(zygomatic)

post-orbital

pre-frontal

post-frontal

dentary angular

sur-angular

italic underlined = absent in any form in human

Alligator Skull

Sq

QJ L

PrFPO

J mx pmxsur

dentan

nasals

frontalparietal

Palatal Series

vomer

palatines

pterygoids

para-sphenoid

Amniote Orbital SeriesGroup Pre-

frontalLacrimal Jugal Post-

orbitalPost-

frontal

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

lacrimal

jugal

post-orbital

pre-frontal

post-frontal

Amniote Temporal SeriesGroup Squamosal Quadratojugal

turtles present present

lizards & snakes present present in tuataras (absent in all others)

birds present present

crocodylians present present

mammals Present(squamous part of

temporal)

absent

quadrato-jugal

squamosal

Subphylum Vertebrata

hagfis

hes

lam

preys

Chondrichth

ys

Actin

optery

gii

coel

acan

ths

lungfis

hes

amphib

ians

Mam

mal

ia

Reptil

ia

premaxilla, maxilla, dentary, angular, surangular(Osteichthys)

*surangularlost

*mobilemaxilla

jawspalatoquadrate, Meckel’s cartilage, hyomandibula (Gnathostomata)

Subphylum Vertebrata

hagfis

hes

lam

preys

Chondrichth

ys

Actin

optery

gii

coel

acan

ths

lungfis

hes

amphib

ians

Mam

mal

ia

Reptil

ia

nasal, parietal, postparietal, 4 opercular bones, vomer, dermopalatine, pterygoid (Osteichthys)

operc. lost (Tetrapoda)

*

frontals, squamosal, quadratojugal

*quadratojugal lost

Subphylum Vertebrata

hagfis

hes

lam

preys

Chondrichth

ys

Actin

optery

gii

coel

acan

ths

lungfis

hes

amphib

ians

Mam

mal

ia

Reptil

ia

lacrimal, undifferentiated infraorbitals (Osteichthys)

jugal, postorbital, prefrontal, postfrontal

(Tetrapoda)

*postorb., prefr., & postfr. lost

*

Amniote Skull OpeningsSpace 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

1 opening 2 openings

no openings

Amniote Skull Openings

no openings(turtles)

1 opening 1 opening(mammals)

Amniote Skull Openings

Montre

mat

a

Met

ather

ia

Euther

ia

Testu

dines

Lepid

osauria

Croco

dylia

Aves

1 opening2openings

mandibular &antorbitalfenestras

NaresActinopterygiian nares

Water flows in anterior naris, over olfactory epithelium, & out posterior naris.

NaresTetrapod nares

Air enters external naris flows over olfactory epithelium and exits into oral cavity through internal naris (choana).

Human Nasolacrimal Duct

The Tetrapod Middle EarTetrapod upper jaw fused to skull.

Hyomandibula not supporting jaws.

Stapes = tetrapod hyomandibula; small, slender middle ear bone, conducts sound to otic capsule

Stapes/Columella

innerear

Subphylum Vertebrata

hagfis

hes

lam

preys

Chondrichth

ys

Actin

optery

gii

coel

acan

ths

lungfis

hes

amphib

ians

Mam

mal

ia

Reptil

ia

internal nares;stapes (modifiedhyomandibula)

(Tetrapoda)

**secondary palate in crocodilians & many turtles

* **

*secondary palate

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.)

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.

Mammalian Skull

Jaws & Jaw Joint

Meckel’s cartilage

PalatoquadrateHyomandibula

articular

quadrate

Meckel’s cartilage

Jaws & Jaw Joint

stapes

articular

quadrate

dentary angular

squamosal

maxilapmxjugal

Non-mammalian tetrapods

Jaws & Jaw Joint

stapes

articular

quadrate

dentary

squamosal

maxilapmxjugal

angular

Fossil mammal-like “reptile”

jugal

Jaws & Jaw Joint

stapes

articular

quadrate

dentary

squamosal

maxilapmx

angular

jugal

Jaws & Jaw Joint

stapes

malleusincus

dentary

squamosal

maxilapmx

tympanicannulus

mammal

jugal

Jaws & Jaw Joint

dentary

squamosal

maxilapmx

tympanicbulla

mammal

Jaw Articulation

Human Middle Ear

Amniota

Montre

mat

a

Met

ather

ia

Euther

ia

Testu

dines

Lepid

osauria

Croco

dylia

Aves

temporal bone, sphenoid bone,occipital bone, “new” jaw joint, incus & malleus, 2ary palate