ENDOSKELETON OF VERTEBRATESAxial Skeleton

COMPONENTS OF THE ENDOSKELETONCARTILAGE CHONDROGENESISBONES OSTEOGENESISDIVISIONS:1.) AXIAL VERTEBRAE, RIBS, SKULL, HYOID BONE, STERNUM, JAW2.) APPENDICULAR LIMBS, GIRDLES, FINS

BASIC STRUCTURE OF A VERTEBRAE

1.) ATYPICAL VERTEBRATE2.) TYPICAL VERTEBRATESA. NEURAL SPINEB. TRANSVERSE PROCESSC. NEURAL CANALD. CENTRUM

VERTEBRAE, RIBS AND STERNAE

1.) ARCH 1 OR 2 ARCHES NEURAL ARCH SPINAL CORDFORMS THE HAEMAL CANAL WHICH ENCLOSED THE CAUDAL ARTERY AND VEINS

2.) PROCESSES PROJECTIONS ARCHES CENTRA

3.) CENTRUM BODY OF VERTEBRATES

PROCESSES PROJECTIONS FROM ARCHES AND CENTRA

1.) DIAPHOPHYSIS LATERAL PROJECTIONS (TRANSVERSE PROCESS)

2.) ZYGAPOPHYSIS ARTICULATION BETWEEN SUCCESSIVE VERTEBRAE A. PREZYGAPOPHYSIS-DIRECTED ANTERIORLY B. POSTZYGAPOPHYSIS-DIRECTED POSTERIORLY

3.) PARAPOPHYSIS - LATERAL PROJECTIONS FROM THE CENTRA OF FEW TETRAPODSCENTRA OF BICIPITAL RIB (2 HEADED RIBS)

ZYGAPOPHYSISDIAPOPHYSIS

4. )HYPAPOPHYSES MIDVENTRAL PROJECTIONS FROM THE CENTRA OF THE SNAKES AND AMNIOTES - SITES OF ATTACHMENT FOR CERTAIN MUSCLES AND TENDONS

5.) BASOPOPHYSES CENTRA OF FISHES

HYPAPHOPHYSIS

TYPES OF CENTRUM (BODY) 1.) AMPHICOELOUS CONCAVE AT BOTH ENDS - EX. FISHES, TELEOSTS - CENTRUM IS OCCUPIED BY SOFT NOTOCHORDAL TISSUE2.) PROCOELOUS CONCAVE ANTERIORLY, CONVEX POSTERIORLY - EX. FROGS3.) OPISTHOCOELOUS CONCAVE POSTERIORLY, CONVEX ANTERIORLY - EX. REPTILES SALAMANDERS

ACOELOUSHETEROCOELOUSAMPHICOELOUSOPISTHOCOELOUS

4.) HETEROCOELOUS SADDLE SHAPED CENTRUM EX.CERVICALVERTEBRAE OF BIRDS

5.) ACOELOUS FLAT CENTRUM AT THE BOTH ENDS EX. MAN

VERTEBBRAE SKULL:

3 BASIC COMPONENTS

1.) NEUROCRANIUM CHONDROFACATON/ ENDOSKELETON (PRIMARY BRAINCASE)

2.) DERMATOCRANIUM ROOFING BONES

3.) SPLANCHNOCRANIUM VISCERAL SKELETON 1.) FLOOR OF THE SKULL 2.) ROOF 3.) JAWS

I. FUNCTIONS OF THE NEUROCRANIUM

1.) PROTECTS THE BRAIN AND SENSE ORGAN

2.) ARISES AS CARTILAGE TO FACILITATE HEAD CIRCUMFERENCE REDUCTION DURING PARTURITION

3.) OSSIFY PARTLY OR WHOLLY AS HARD BONE

CARTILALIGINOUS STAGE OF SKULL

1.) PARACHORDAL CARTILAGE ANT. END OF THE NOTOCHORD BENEATH THE MIDBRAIN - INCORPORATED TO THE NOTOCHORD TO FORM BASAL PLATE (SINGLE, BROAD CARTILAGE)

2.) PRECHORDAL CARTILAGE- UNDERNEATH THE FOREBRAIN- EXPANDS AND UNITE ACROSS THE MIDLINE AT THE ANT. ENDS THEN FORM ETHMOID PLATE (FLOOR OF THE SKULL)

SENSE CAPSULES:

1.) OLFACTORY (NASAL) CAPSULE SURROUNDING THE OLFACTORY EPITHELIUM

2.) OTIC CAPSULE COMPLETELY SURROUNDING THE OTOCYSTS W/C IS THE DEVELOPING INNER EARFORAMINA - TRANSMITS NERVES AND VASCULAR CHANNELS

3. OPTIC CAPSULE - FORMS AROUND THE RETINA,ACT AS AN ORBIT - THE SCLEROTIC COAT OF THE EYEBALL - DOES NOT FUSE WITH THE RETINA OF THE NEUROCRANIUM, THUS THE EYEBALL IS FREE TO MOVE INDEPENDENTLY OF THE SKULL - EYE MOVEMENTS: A. SACCADIC C. CONJUGATIONB. PURSUIT D. FIXATION

SCLERAL RINGS - surrounds the eye and maintain the shape of the eyeballSCLERA white of the eye, protected by sclerotic coatPLICAE SEMILUNARIS - third eyelid that corresponds to the nictitating membrane of the frogs eyeHYPOPHYSEAL FENESTRA accomodates the hypophysis and the internal carotid arteriesPRECHORDAL CARTILAGE- trabeculae cranii

OSSIFICATION CENTERSOCCIPITAL CENTER - the 4 bones surrounding the foramen magnum - 2 exoccipital, 1 basioccipital, 1 supraoccipital - in man, these 4 bones unite to form the occipital bone with occipital condyles - in modern amphibians, one or more of these bones remain cartilaginous

2. SPHENOID CENTER underlying the brain- BASISPHENOID- ALISPHENOID- PRESPHENOID- PLEUROSPHENOID- ORBTIOSPHENOID- In man, these bones are fused forming the single sphenoid bone - in frogs, parasphenoid is the only ossified bone

3. ETHMOID CENTER- SPHENETHMOID in frogs, the sole bone arising from ethmoid and sphenoid- MESETHMOID contributes to the cartilaginous nasal septum in birds and mammals- ECTHETHMOID develop from nasal passageway of sphenodon - TURBINAL BONES (CHONCHAE)- walls of the nasal passageways of crocodilians, birds, and mammals- CRIBRIFORM PLATE in mammals, this is perforated by olfactory foramina which transmit bundles of olfactory nerve fibers from olfactory epithelium to the brain

4. OTIC CENTER- bones forming the earsa. prooticc.epioticb. opisthoticd. periotic- in birds and mammals, the 3 bones are fused- in reptiles, opisthotic fused to exoccipital- periotic and squamosal temporal bone

DERMATOCRANIUM- Bones closed the Skull (Dermal Bones)- Forms to the top side of the skull - Function: For Protection, serve as roof of the skull- Components:1. Roofing Bones Fronto Parietal 2. Primary Bone of the Palate3. Dermal Bone of the Jaw4. Opecular Bone Fishes - Supraopercular- Preopercular - Interopercular - Large Opercular

UPPER JAW- Palaquadrate Cartilage Ossify to form the right and left jawIn Fishes Remains of cartilage for Chondrichthyes & for osteichthyes they Ossify to form the Quadrate bone.Maxillae & Premaxillae ToothBearing of Bones Primary Palatal Bone Roof of the Dropharyngeal cavity of the fishes & of the oral cavity of tetrapods.

Contd..

Components:1. Parasphenoid Unpaired Bone2. Vomers3. Palatine 4. Pterygoids5. Ectopherygoids6. Choanae Internal Nares

FUSION OF NEUROCRANIUM AND DERMATOCRANIUMFISHES - Cyclostomes and Amia remains cartilaginous - Garfishes ossifies - Roofing Bones of the bony Fishes1. frontal2. supraoccipital3. parietal4. postemporal

2. AMPHIBIANS- Anurans and urodeles, the neurocranium remains cartilaginous-in apodans, it is ossified for burrowing- anurans are with platybasic skull3. REPTILES - with ossified neurocranium, dentary, and occipitals - temporal fossae a partial complete secondary palate - temporal fenestra cavernous opening of temporal region of amniotes

TYPES OF TEMPORAL FOSSAE1.ANAPSIDS no temporal fossae- ex. Dinosaurs2.SYNAPSIDS with one temporal fossae - ex. Extinct reptiles3.DIAPSIDS - with 2 temporal fossae- living reptiles,crocodiles,sphenodon4. EUROPSIDS with one lateral temporal fossae - ex. Extinct reptiles*** TURTLE- with enigmatic skull - no temporal fossae, loss dermal bones

4. AVES- ossified bone, bulging outward forming TROPIBASIC SKULL- bones forming the beaks- upper jaw * maxillae,premaxillae,nasals- lower jaw * dentary- 2 functional regions of the skull1. solid bony box (neurocranium & dermatocranium)- houses the brain,olfactory organs, eyeball, and hearing and equilibrium complex

2. elongated beak- procuring and handling area

4. MAMMALS- skulls are with fontannels- modifications:1. dentary forms the mandible - the only movable bone of the lower jaw2. temporal region 23. altered side secondary palate- pterygoid bone- auditory ossicles* malleus, incus, stapes

CRANIAL KINESISThe independent movement of parts of the skullThe condition in which snakes swallow food due to presence of ectopterygoid boneIn mammals ectopterygoid is lost, the styloid process is left, located in the visceral skeleton

III. SPLANCHNOCRANIUMSkeleton of the pharyngeal archesIn fishes the skeleton of jaws, gill archesThe balstemas are from the neural crests and arise from the neuroectoderm

MODIFICATION OF THE SPLANHCNOCRANIUMCYCLOSTOMES- unique visceral skeleton- no palatoquadrate or merkels cartilage - a cartilaginous branchial basket located at the base of the skin of the pharyngeal arch2. BONY FISH - visceral skeleton resembles that of the shark except that is ossifies- hyoid arc consist of a larger number of components

TYPES OF JAW SUSPENSIONHYOSTYLIC fishes- hyomandibular cartilage is braced against the otic capsule- posterior end of the palatoquadrate is braced against the hyomandibulaB. AMPHISTYLIC older sharks- hyomandibula and one or more processes of palatoquadrate are braced independently against the braincaseC. AUTOSTYLIC - lungfishes and tetrapods- palatoquadrate is attached independently against the braincase

HYOSTYLIC JAWAMPHISTYLIC JAWAUTOSYSTYLIC JAWAUTOSTYLIC JAW

3. AMPHIBIANS- Palatoquadrate is enclosed by the membrane bone and its caudal end become quadrate boneMerkels cartilage are invested, caudal ends become the articular boneIn anurans, hypomandibula become the columella & the remainder of the 2nd,3rd,part of the 4th arch become the HYOID SKELETON4TH & THE 5TH become the cartilage of the larynx4. MAMMALS- Articular and quadrate bones become ossicles of the middle ear (malleus and incus)