Lesson 9 Skull

THE SKULL

         Skull consists of flat bones. Mostly form immoveable joints. Skull provides protection to the brain and special sense organs (Smell, Taste, Sight, Equilibrium, and hearing). It provide opening for the air and food and the jaws including the teeth for the mastication. The skull is a four sided pyramid having dorsal, lateral, ventral and caudal surfaces.

Dorsal surface can be divided into four regions: Parietal, Frontal, Nasal, and Premaxillary Region

Lateral surface can be divided into three regions: Cranial Region, Orbital Region, Preorbital Region

Ventral surface can be divided into three regions: Cranial Region, Choanal Region, Palatine Region

Caudal surface is Occipital region.

The Skull can be divided into cranial and facial bones at the level of rostral border of the eye.

THE BONES OF THE CRANIAM

Single bones     Occipital, Sphenoid, Ethmoid

Paired bones    Interparietal, Parietal, Frontal, Temporal

THE BONES OF THE FACE

Single bones:  Vomer, Mandible, Hyoid

Paired bones: Maxilla, Premaxilla, Palatine, Pterygoid, Nasal, Lacrimal, Malar, Turbinates

The Pterygopalatine fossa contain maxillary foramen, sphenopalatine foramen and caudal palatine foramen

The Orbital group of Foramina

HORSE        Ethmoid, Optic, Orbital, Round, Trochlear, Alar Canal (Alar parvum and Rostral alar)

OX               Ethmoid, Optic, Orbitorotendum, Ovale

THE SKULL

HORSE

OX

Long narrow four sided pyramid

Shorter, wider and clearly pyramidal in shape

Cranial cavity is large

Cranial cavity is small

Horns are absent

Horns are present

Premaxilla bend downward

Premaxilla is straight

Zygomatic arch is formed by maxilla, malar and temporal bones

Zygomatic arch is formed by malar and temporal bones

Facial crest is present

Facial tubercle is present

Incisive foramen is present in premaxilla bone

Incisive fissure is present in premaxilla bone

Condyle on temporal bone is concave

Condyle on temporal bone is convex

Pterygopalatine fossa is shallow

Lacrimal bulla is present in orbit

Sphenopalatine and maxillary foramen are superficially placed.

Pterygopalatine fossa is deeply placed

Lacrimal bulla is absent in orbit

Sphenopalatine and maxillary foramen are deeply placed

Preorbital region is long and low in height.

Preorbital region is short and high

Condyloid fossa has only one foramen, the hypoglossal

Condyloid fossa has two foramina, the hypoglossal

and condyloid

Paramastoid process is long and concave medially.                                                                                                                                                                                                                                                                                                                                                                                                                                                                              

Paramastoid process is short and convergent                                                                                                                                                                                                                                                                                                                                                                                                                                                                                          

Bulla tympanica is an eminence

Bulla tympanica is large and laterally compressed

External Acoustic meatus is directed upward and outward.

Foramen lacerum is a slit like opening

Hard palate is narrow and long

External Acoustic meatus is directed straight outward.

Muscular process is a sharp spine

Hard palate is wider and shorter

Foramen lacerum is irregular in shape

Muscular processes are long triangular plates with sharp points

Basilar tubercles are small

Basilar tubercles are larger

Posterior nares are wide, oval in shape,

Posterior naries are very narrow, Vomer don't reach to their

ventral floor of the nasal cavity

Nuchal surface is trapezoidal in outline

Nuchal surface is extensive pentagonal in outline

Nuchal crest is present

Nuchal lines are present

Occipital Condyles are closer together                                                                                                                                                                                                                                                                                       

Occipital Condyles are further apart and are clearly divided into

dorsal and ventral surfaces

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