[2] Lecture 10-skeletal System 2 Flashcards
Components of the vertebrate skull organization:
Chondrocranium:
Neurocranium and splanchnocranium
Dermatocranium
Neurocranium forms the
Braincase
Splanchnocranium forms the
Gill arches
DO we have dermal bone?
No
The braincase or neurocranium has 3 pairs of cartilaginous capsules housing special sensory organs [capsules]:
Olfactory
Optic
Otic
The floor of the braincase or neurocranium forms from 2 pairs of cartilaginous plates,explain:
Parachordals: flank [side] the notochord
Prechordals: in front of notochord
Hole spinal cord exits from braincase:
Foramen magnum
Asso. W/ sense of smell
Olfactory
Asso. W/ sense of sight
Optic
Asso. W/ sense of balance
Otic
Below the Foramen magnum
Basioccipital
Paired; lateral to foramen
Exoccipital
Above the Foramen magnum
Supraoccipital
Endochondral ossifications:
Basioccipital
Exoccipital
Supraoccipital
Basisphenoid/presphenoid
How many pairs of cartilaginous or bony arches make up splanchnocranium?
6 pairs
1st and second arches of the splanchnocranium:
Mandibular and hyoid arch
Dorsal and ventral part of mandibular arch:
Dorsal: palatopterygoquadrate bar- ossification=sphenoid
Ventral: meckel’s cartilage: quadrate and articular
What does the hyoid arch do in many fishes?
It braces the palatopterygoquadrate bar against the braincase
When the hyoid arch [derived from the 2nd gill arch] braces the upper jaw against the neurocranium
Hyostylic articulation
When the upper jaw is fused to the brain case:
Autostylic articulation
Ex of hyostylic jaw:
Elasmobranchs, holosteans, teleosts, and dipnoans
Ex of autostylic jaw:
Chimaeras and lungfishes
Jaw articulation is between quadrate and articular
Primitive tetrapods to amphibians skull:
Reduction in dermal bones,
Retention of considerable cartilage,
Paired occipital condyles,
Autostylic jaw articulation,
Dermal skull elements of primitively tetrapods
Primitive tetrapods had a lot of dermal bones and they’re named as human bones but not really sure if they are same bone…
Many bones are no longer in human anatomy, so they were lost. But some are still there.
Amphibian dermal series: Cheek:
Squamosal
Quadratojugal: forms cheek arch
Amphibian dermal series Tooth-bearing:
Premaxilla
Maxilla
Generalization Reptile skull:
Well ossified,
Boxlike skulls->arches and openings,
Dermatocranium reduced,
Single median occipital condyle,
Well-developed jaw muscles r/t muscle attachment on side of skull- arches and openings.
Many reptilian dermal bones rate homologous w/ mammal skulls.
No arches and no additional openings
Anapsid
Ex of anapsid
Cotylosaurs [and maybe turtles]
Both lateral and dorsolateral openings- 2 arches
Diapsid -found in most reptiles
Ex of diapsid:
Sphenodon,
May be a variant of a diapsid skull
Single dorsolateral opening bounded inferiorly by postorbital and squamosal bones
Euryapsid [parapsid]
Ex of Euryapsid [parapsid]
Plesiosaurs and icthyosaurs
Found in mammal-like reptiles and mammals.
Single opening bounded inferiorly by the zygomatic arch
Synapsid-mammals—-us
Reptilian emargination on superior skull:
Allows muscle to attach for strong neck attachment to head and body
One of the benefits of zygomatic arch:
Allows for increase SA of muscle to have more forcible bite
Jaw articulation in reptiles and amphibians is:
Between the articular and quadrate
=autostylic
Articular is dervied from the proximal end of
Meckel’s cartilage
1st branchial arch
Quadrate is derived from proximal end of
Palatopterygoquadrate cartilage
1st branchial arch
Hyomandibular is no longer need to brace upper jaw against braincase what happens to it?
It becomes the columella [stapes forms proximal portion]
Extends from the tympanic membrane to fenestra ovalis
Opening into inner ear
Fenestra ovalis
1st gill slit becomes=
Eustachian tube
Amphibian and reptile jaws are
Autostylic
Amphibian vs. reptile tympanic membrane:
Amphibian-high
Reptile-low
What happens in between amphibian and reptile development w/ ear?
The quadrate and articular in amphibian which is a part of the mandible becomes malleus [articular] and incus [quadrate] in reptile.
Stapes became longer in reptile.
Ossifications from the palatopterygoquadrate
Epiterygoids
Floor of the braincase
Basisphenoid
Pelycosaurs braincase:
- not fused to epipterygoids
- epipterygoids do not extend to dermal roof.
Therapsids braincase:
Basisphenoid (braincase floor) fused to epiterygoids and pterygoids
Epipterygoids do not extend to dermal roof
Mammal braincase:
Basisphenoid fused to epipterygoids and pterygoids
Epipterygoids extend to dermal roof
Serves as sites for muscles involved in jaw movement in mammals:
Pterygoid plates
Primary palate
Floor of braincase —
Human- roof of nose
Secondary palate consists of:
Premaxillae
Maxillae
Palatines
Function of secondary palate:
Separate food stream from air stream
Why can cleft palate occur?
The bone is formed from the outside-in…sometimes it doesnt meet up completely.
Development of secondary palate is especially important in:
homeotherms
Zygomatic arch is formed by:
Jugal and squamosal bones
Crests for muscle attachment:
Sagittal and nuchal crest
Mammalian jaw articulation:
Crainostylic
Btw Denmark and temporal bones
What happened to quadrate and articular:
Incus and malleus in middle ear
CLearly define structures at TMJ human:
Capsule
Temporomandibular ligament
Stylomandibular ligament
Attachment for falx celebri :
Crista Galli
4 skull sutures:
Sagittal
Lambdoidal
Coronal
Frontal
4 fontanelles
Anterior
Posterior
Posterolateral
Anterolateral
Superior and posterior boundary of temporal
Inferior temporal line
Anterior boundary of temporal
Frontal process of zygomatic
Inferior boundary of temporal
Zygomatic arch
Floor of temporal [4 components]:
Greater wing of sphenoid
Squamous temporal
Frontal
parietal
What is in temporal region:
Temporalis muscle
Deep temporal nerve and arteries
Zygomaticus nerve
Attachment of temporalis fascia
Superior temporal line
Attachment of temporalis muscle
Inferior temporal line
Elevates and protracts mandible
Masseter
Elevates and retracts mandible
Temporalis
Protracts mandible; depresses chin[bilateral; grinding(unilateral)]
Lateral pterygoid
Elevates, protracts, grinding [unilateral]
Medial pterygoid
Between head of mandible (condyloid process) and mandibular fossa of temporal bone, what type of joint:
Synovial joint
Capsule of TMJ allows:
Mandible to protracts, retract, and elevate/depress
TMJ 3 ligaments:
Temporomandibular
Stylomandibular
Sphenomandibular
