Cranial vault

Question 1

Skull ossification

Answer 1

Vicerocranium (facial skeleton)

• Intramembranous: facial bones
• Endochondral: ossicles, styloid process of temporal bone, hyoid

Neurocranium (cranial vault)

• intramembranous: calvaria (skull cap)
• endochondral: base of cranial vault
• all cranial nerves leave cranial vault thru endochondral portion

Question 2

Neurocranium venous system

Answer 2

• Diploic v. drain Diploe (spongy bone)
• Drains into Emissary v
• Valveless

Question 3

Craniosyntosis

Answer 3

• premature closure of cranial sutures

Question 4

Trigonocephaly

Answer 4

• premature closure of metopic suture
• linked to brain development
• halt in brain development leads to early closure of cranial sutures

Question 5

Scaphocephaly

Answer 5

• early closure of saggital suture
• results in a long, wedge-shaped skull

Question 6

Brachycephaly

Answer 6

• early closure of coronal suture
• results in decreased A-P and increased bilateral dimensions
  *

Question 7

Plagiocephaly

Answer 7

• early closure of suture on one side results in asymmetrical skull shape
• may be postural in origin; i.e. lying on one side

Question 8

Microcephaly

Answer 8

• born with normal size skull
• early closure of sutures & fontanelles results from failure of brain to grow
• result is small skull
• brain development matched with bone development

Question 9

Arterial supply to brain & brain stem

Answer 9

Internal carotid & Vertebral (C1-6 Transverse Foraminae) arteries supply blood to brain & brain stem:

• Anterior: Frontal, ethmoid, sphenoid
• Middle: Temporal & sphenoid
• Posterior: Sphenoid, Temporal, Parietal, Occipital

Question 10

Cerebral arterial circle of (Willis)

Answer 10

Internal carotid a. br.

• Anterior communicating a.
• Anterior cerebral a.

Vertebral a. br

• Basilar a.
• Posterior cerebral a.
• Posterior communicating a.
• Ant. Inf. Cerebellar A. (AICA)
• PICA

Question 11

Cranial dura layers

Answer 11

• Cranial dura has:
  
  • Periosteal layer
  • Meningeal layer
• Dural venous sinuses formed where 2 layeers separate; receive blood from cerebral v. & CSF from arachnoid villi
  
  • S. Saggital sinus
  • I. Saggital sinus -> Great Cerebral v. (of Galen)
  • Transverse sinus
  • Sigmoid sinus
  • Drain into Interal jugular v.

Question 12

Emmisary veins

Answer 12

• scalp infection may enter cranial vault via emissary veins
• Epidural bleeds: blow developing due to fusion of layers

Question 13

Contents of Cavernous sinus

Answer 13

• Infection may result in thrombosis of sinus and/or meningitis:
  
  • CN III, IV, VI, V1 & V2
  • Cerebral v. (intracranial)
  • Ophthalmic v.
  • Pterygoid venous plexus (extracranial)
  • Internal carotid a.
• lie on lateral aspect of body of sphenoid

Question 14

Superior orbital fissureSuperior orbital fissure: strucutres passing through

Answer 14

• CN III
• CN IV
• V1
• CN VI
• Foramen on Sphenoid

Question 15

F. Rotundum: strucutres passing through

Answer 15

• V2
• sphenoid

Question 16

F. Ovale: strucutres passing through

Answer 16

• V3
• sphenoid

Question 17

F. Spinosum: strucutres passing through

Answer 17

• Middle Meningeal a.
• b/w Sphenoid & Temporal

Question 18

F. Lacerum: strucutres passing through

Answer 18

• nothing passes through it
• passing on top are: recurrent meningeal nerve (from CN V3, into the endocranium) and the middle meningeal artery

Question 19

Internal acoustic meatus: strucutres passing through

Answer 19

• CN VII
• CN VIII
• Temporal

Question 20

Jugular foramen: strucutres passing through

Answer 20

• CN IX
• CN X
• CN XI
• in b/w Temporal & Occipital

Question 21

Hypoglossal foramen: strucutres passing through

Answer 21

• CN XII
• Occipital