A1 - Os occipitale

Question 1

What is the cranium formed by?

Answer 1

• Roof:
  
  • Os interparietale
  • Os parietale
  • Os frontale
• Lateral walls on each side:
  
  • Os temporale
• Floor:
  
  • _​_Os sphenoidale
    
    • Os praesphenoidale
    • Os basisphenoidale
  • Os occipitale, pars basilaris
• Nuchal wall:
  
  • _​_Os occipitale, pars squamosa
  • Os occipitale, pars lateralis
• Nasal wall:
  
  • _​_Os ethmoidale

Question 2

Which structures should be mentioned?

Answer 2

• Foramen magnum

Pars basilaris

• Tuberculum pharyngeum (ca) (outer surface, median, ventral)
• Tuberculum musculare (outer surface, ventral. Attachment of m. longus capitis)
• Fossa cranii caudalis
  
  • Impressio pontina (rostral)
  • Impressio medullaris (caudal)
• Foramen jugulare (between os occipitale and os petrosa)
• Fissura petrooccipitalis (car, ru)

Pars lateralis

• Condylus occipitalis (forms art. atlantooccipitalis)
• Processus paracondylaris (lateral from condylus occipitalis)
• Fossa condylaris dorsalis (depression dorsal to condylus occipitalis)
• Fossa condylaris ventralis (between condyle and proc. paracondylaris. Depression ventral to condylus occipitalis)
• Canalis n. hypoglossi (canal for n. hypoglossus)
• Canalis condylaris (ca, bo) (canal for sinus condylaris)

Squama occipitalis

• Protuberantia occipitalis externa (eq, bo, ca) (between crista nucha / linea nucha)
• Crista nuchae (eq, ca, su)
• Linea nuchae (bo,) (crista nucha corresponds to linea nucha)
• Crista sagittalis externa (eq, ca)
• Linea temporalis
• Protuberantia occipitalis interna (bo, su)
• Processus tentoricus (eq, ca) (part of tentoriu cerebelli osseum)
• Impressio vermialis (inner surface, impression by vermis cerebelli)
• Sinus frontalis caudalis (bo, su)
  
  • Septum sinuum frontalium
• Fossa cerebellaris (for cerebellum, inner surface)

Question 3

Give the interspecies differences of os occipitale

Answer 3

Pars basilaris:

• Tuberculum pharyngeum (ca)

Pars lateralis:

• Canalis condylaris (ca, bo)

Squama occipitalis:

• Protuberantia occipitalis externa (eq, bo, ca) (ø su)
• Crista nucha (eq, ca, su)
• Linea nucha (bo)
• Crista saggitalis externa (eq, ca)
• Protuberantia occipitalis interna (bo, su)
• Processus tentoricus (eq, ca)
• Sinus frontalis caudalis (bo, su)
  
  • Septum sinuum frontalium

Question 4

Name the parts of os occipitale

Answer 4

• Pars squamosa
• Pars lateralis
  
  • ​Forms the lateral limits of for. magnum
• Pars basilaris
  
  • ​Forms posterior part of the base of skull
  • In front of for. magnum
  • Articulates with os sphenoidale through synchondroses sphenoidalis

Question 5

Which parts of the skull does os occipitale form?

Answer 5

• Floor:
  
  • ​Pars basilaris of os occipitalis
  • Os sphenoidale
• Nuchal wall:
  
  • ​Pars squamosa of os occipitale
  • Pars lateralis of os occipitale