L4 - Osteology of the skull

• There is an enlargement in the cervical and lumbar regions of the spinal cord because there are more fibers there that will go to innervate the arms and legs
• Spinal nerves gives segmental innervation
• Dermatome is the sensory area supplied by a spinal nerve
• Myotome is a group of muscles innervated by a spinal nerve
• The grey matter of the spinal cord makes up the

  • ventral horn
  • dorsal horn
  • lateral horn (dont have this at all spinal levels)
  • grey commissure
• The grey commissure is the fiber tract that connects the grey matter from both sides of the spinal cord
• White matter is made up of highly organized myelinated fiber tracts. White matter in the spinal cord makes up the

  • dorsal funiculus (sensory travelling up)
  • lateral funiculus
  • ventral funiculus (motor travelling down)
• A group of neuronal cell bodies in the PNS is called a ganglion
• A group of neuronal cell bodies in the CNS is called a nucleus
• A bundle of axonal fibres in the PNS is called nerves
• A bundle of axonal fibres in the CNS is called tract, fasciculus column, funiculus lemniscus
• The skull has a total of 22 bones
• All the bones in the neurocranium

  • parietal (2)
  • temporal (2)
  • frontal
  • ethmoid
  • occipital
  • sphenoid
• All bones in the viscerocranium

  • maxilla (2)
  • zygomatic (2)
  • nasal (2)
  • lacrimal (2)
  • palatine (2)
  • inferior nasal conchae (2)
  • vomer
  • mandible
• The pterion is a weak point in the skull. Deep to the pterion is the middle meningeal artery. An extradural hematoma can occur from an impact to the pterion. Symptoms include

  • brief loss of consciousness followed by a lucid interval
  • drowsiness and coma due to compression of brain as blood mass increases
• Label the skull

  A) parietal bone

  B) occipital bone

  C) temporal bone

  D) ethmoid bone

  E) sphenoid bone

  F) frontal bone

  G) coronal suture

  H) sagittal suture

  I) lambdoidal suture

  J) squamous suture

  
• The anterior fontanelle becomes the bregma and the posterior fontanelle becomes the lambda
• Craniosynostosis is the premature fusion of sutures. Leads to the skull having an abnormal shape
• There are 4 regions of the temporal bone

  • squamous
  • mastoid
  • tympanic
  • petrous
• Label the temporal bone

  A) squamous portion

  B) external acoustic meatus

  C) mastoid region

  D) mastoid process

  E) styloid process

  F) zygomatic process

  G) mandibular fossa

  H) tympanic region

  
• Label the anterior sphenoid bone

  A) greater wing

  B) lesser wing

  C) optic canal

  D) superior orbital fissue

  E) foramen rotundum

  F) foramen ovale

  G) foramen spinosum

  
• Label the posterior sphenoid bone

  A) superior orbital fissure

  B) pterygoid process

  
• Label the ethmoid bone

  A) crista gali

  B) cribriform plate

  C) orbital plate

  D) ethmoidal air cells

  E) perpendicular plate

  F) middle nasal concha

  G) lateral mass

  
• Label the maxilla

  A) frontal process

  B) infraorbital foramen

  C) anterior nasal spine

  D) alveolar margin

  
• Label the paranasal sinuses

  A) frontal sinus

  B) ethmoidal air cells

  C) sphenoidal sinus

  D) maxillary sinus

  
• The frontal lobe sits in the anterior cranial fossa
• The temporal lobe sits in the middle cranial fossa
• The cerebellum and brainstem sit in the posterior cranial fossa
• CN I - the olfactory nerve passes through the cribriform plate
• CN II (optic nerve) and the ophthalmic artery pass through the optic foramen (canal)
• CN III (oculomotor nerve), CN IV (trochlear nerve), CN V1 (trigeminal nerve ophthalmic division), and CN VI (abducens nerve) pass through the superior orbital fissure
• CN V2 (trigeminal nerve maxillary division) passes through the foramen rotundum
• CN V3 (trigeminal nerve mandibular division) passes through the foramen ovale
• The middle meningeal artery passes through the foramen spinosum
• The internal carotid artery passes through the foramen lacerum
• CN VII (facial nerve) and CN VIII (vestibulocochlear nerve) passes through the internal auditory meatus
• The jugular vein, CN IX (glossopharyngeal nerve), CN X (vagus nerve), and CN XI (accessory nerve) passes through the jugular foramen
• CN XII (hypoglossal nerve) passes through the hypoglossal canal
• The brain stem, spinal cord, and vertebral arteries pass through the foramen magnum