The skull of the dog

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Abstract

Fifty bones compose the skull of the dog

There are many variations in the shape of the skull amongst the different breeds of the dog. All the dogs were domesticated from wolves, from the late Paleolithic (about 14000 years ago), but different purposes led to different morphology.  The canine breeds are grouped in 3 categories:

1.      Dolichocephalic: those breeds that have a long narrow head, like Greyhound, Afghan or Whippet.

2.      Brachycephalic: those breeds that have a short, strong head like Bulldog, Pekingese or Boston terrier. In some breeds, the lower jaw protrudes forwards, producing the condition known as “prognathism of the mandible”.

3.      Mesaticephalic: meaning skull of medium proportion, like Setter, Beagle or German Shepherd. Mesaticephalic is the nearest of the wolf size. 

Fifty bones compose the skull of the dog. Those that close the brain form the cranial part (cranium), while those in front of the skull build the facial part (facies). Latin is generally used to name the bones and other anatomical organs. 

The bones of the cranial part

  • The basis of the skull

1.      unpaired basioccipital (pars basilaris ossis occipitalis)

2.      unpaired basisphenoid & presphenoid bone (os basisphenoidale et os presphenoidale)

  • The back of the skull

1.      unpaired supraoccipital bone (squama* occipitalis)

2.      paired exoccipital (partes laterales)

  • The sides of the skull

1.      paired temporal bones (os temporale)

  • The roof of the skull

1.      paired frontale bone (os frontale)

2.      parietal bone (os parietale)

3.      unpaired interparietal bone (os interparietale)

  • The wall that separates the cranial from the facial part

1.      unpaired ethmoid bone (os ethmoidale

The bones of the facial part

  • Lesser jaw

      1. Mandibula

  • Nasal cavity-lateral walls

1.      Paired os lacrimale

2.      Paired os zygomaticum

3.      Paired os maxilla

4.      Paired os incisivum

  • Nasal cavity- floor (= roof oral cavity)

1.      Paired os palatinum

2.      Paired os maxilla

3.      Paired os incisivum

4.      unpaired Vomer

  • Nasal cavity
        1.  os conchae nasalis ventralis
  • Nasal cavity- roof

1.      Paired Os frontale

2.      Paired Os nasale

  • Pharyngeal cavity – roof & walls

1.      Paired os pterygoideum

2.      unpaired os vomer

3.      Paired os palatinum

4.      Paired os sphenoidale 

Openings

 Openings are situated at the basis and the different sides of the skull. They permit the passage of nerves and blood vessels from and to the brain. Here is the list of the more important: here some pictures and a table indicating the transmitted structures

n = nerve, v = vein, a = artery 

Openings

Bones – os

Transmitted structures

Foramen magnum

Occipitale

Spinal cord

Canalis hypoglossi

Occipitale

Hypoglossus n.

Condylar v. & a.

Canalis opticus

Praesphenoidale (ala)

Optic n

Fissura orbitale

Presphenoidale

Ophthalmic n., III, IV, VI n.

Foramen rotundum

Basisphenoidale (ala)

Maxillary n.

Foramen alare caudale

Basisphenoidale -pterygoideus

Maxillary a.

Foramen alare rostrale

Basisphenoidale-pterygoideus

Maxillary a.

Foramen ovale

Basisphenoidale (ala)

Mandibular n.

Sulcus caroticus

Basisphenoidale (corpus)

Internal carotid n.

Foramen spinosum

Basisphenoidale (ala)

Trochlear n. ; mid. Meningeal a.

Foramina ethmoidalia

Frontale

Ethmoid n. & v. & exter. Ethmodal a.

Incisura jugularis

Temporale

IX, X, XI n; internal carotid a.

Fissura petro-occipitale

Temporale / occipitale

Chorda tympani ; greater petrosal n.

Foramen retroarticulare

Temporale -squamosa

Emissary v. for temporal sinus

Meatus acusticus internus

Temporale – pars petrosa

Facial n, cochlear n, vestibular n.

Foramen stylomastoideum

Temporale- pars petrosa

Facial n.

Foramen maxillare

Maxilla

Infraorbital n, v, a

Foramen infraorbitale

Maxilla

Infraorbital n, v, a

Foramen sphenopalatinum

Palatinum

Caudal nasal n, sphenopalatine v & a

Foramen palatinum caudale

Palatinum

Greater palatine n., v & a

Foramen lacrimale

Lacrimale

Drain of tears

Foramen palatinum majus

Palatinum – L. horizontalis

Greater palatine n.

Foramen mandibulae

Mandibula

Mandibular n., v & a

Foramen mentale

Mandibula

Mental n., v & a





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