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 two bones abut or fuse.

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 mandible (dentary) lacrimal zygomatic (jugal) nasal maxilla (includes premaxilla) frontal parietal temporal occipital sphenoid

Human Skull Stutures coronal suture saggital suture squamosal suture lamboidal suture

Human Skull-Temporal Bone Ethmoid middle ear bones in here mandibular fossa of temporal (condylar process of mandible)

Human Middle Ear

Human Skull-Mandible coronoid process condylar process masseteric fossa mandibular notch angle of mandible (angular process) chin (mental process) mental foramen mandibular foramen

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 Nasal capsule (Olfactory capsule) Optic capsule Otic capsule Parachordal 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 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

nasal right frontal maxilla (includes premaxilla) sphenoid left frontal right frontal fontanelle

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.

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 upper jaw pharyngeal openings lower jaw 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 Palatoquadrate Meckel’s cartilage Hyomandibula

Squalus Head Skeleton Chondrocranium palato- quadrate Meckel’s cartilage hyomandibula 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) hyomandibula Meckel’s cartilage palatoquadrate hyomandibula 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- articular joint pmx maxilla

Subphylum Vertebrata hagfishes lampreys Chondrichthys Actinopterygii coelacanths lungfishes amphibians Mammalia Reptilia Dermatocranium (Osteichthys) Chondrocranium, Splanchnocranium Jaws (Gnathostomata) palatoquadrate, Meckel’s cart. dorsal chondro- cranium

 Only Osteichthys. Superficial.  Ancestrally many bones.  Number of bones reduced in many groups. Dermatocranium

Bowfin, Amia calva, Skull

Teleost Upper Jaws mobile maxilla & premaxilla

Tetrapod Skull frontal parietal post- parietal nasal quadratojugal squamosal maxilla pmx 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 PrF PO J mx pmx sur dent an nasals frontal parietal

Palatal Series vomer palatines pterygoids para- sphenoid

Amniote Orbital Series Group Pre- frontal LacrimalJugalPost- orbital Post- frontal turtlespresentabsentpresent absent lizards & snakespresent birdspresentabsentpresentabsent crocodylianspresent absent mammalsabsentpresent absent lacrimal jugal post- orbital pre- frontal post- frontal

Amniote Temporal Series Group SquamosalQuadratojugal turtlespresent lizards & snakespresentpresent in tuataras (absent in all others) birdspresent crocodylianspresent mammalsPresent (squamous part of temporal) absent quadrato- jugal squamosal

Subphylum Vertebrata hagfishes lampreys Chondrichthys Actinopterygii coelacanths lungfishes amphibians Mammalia Reptilia premaxilla, maxilla, dentary, angular, surangular (Osteichthys) *surangular lost * mobile maxilla jaws palatoquadrate, Meckel’s cartilage, hyomandibula (Gnathostomata)

Subphylum Vertebrata hagfishes lampreys Chondrichthys Actinopterygii coelacanths lungfishes amphibians Mammalia Reptilia nasal, parietal, postparietal, 4 opercular bones, vomer, dermopalatine, pterygoid (Osteichthys) operc. lost (Tetrapoda) * frontals, squamosal, quadratojugal *quadratojugal lost

Subphylum Vertebrata hagfishes lampreys Chondrichthys Actinopterygii coelacanths lungfishes amphibians Mammalia Reptilia lacrimal, undifferentiated infraorbitals (Osteichthys) jugal, postorbital, prefrontal, postfrontal (Tetrapoda) *postorb., prefr., & postfr. lost *

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 1 opening2 openings no openings

Amniote Skull Openings no openings (turtles) 1 opening (mammals)

Amniote Skull Openings Montremata Metatheria Eutheria Testudines Lepidosauria Crocodylia Aves 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 hagfishes lampreys Chondrichthys Actinopterygii coelacanths lungfishes amphibians Mammalia Reptilia internal nares; stapes (modified hyomandibula) (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 Palatoquadrate Hyomandibula articular quadrate Meckel’s cartilage

Jaws & Jaw Joint stapes articular quadrate dentary angular squamosal maxila pmx jugal Non-mammalian tetrapods

Jaws & Jaw Joint stapes articular quadrate dentary squamosal maxila pmx jugal angular Fossil mammal-like “reptile”

jugal Jaws & Jaw Joint stapes articular quadrate dentary squamosal maxila pmx angular

jugal Jaws & Jaw Joint stapes malleus incus dentary squamosal maxila pmx tympanic annulus mammal

jugal Jaws & Jaw Joint dentary squamosal maxila pmx tympanic bulla mammal

Jaw Articulation

Human Middle Ear

Amniota Montremata Metatheria Eutheria Testudines Lepidosauria Crocodylia Aves temporal bone, sphenoid bone, occipital bone, “new” jaw joint, incus & malleus, 2ary palate