Brain and the Cranium Flashcards
What is the function of the cranium
Protects brain and sensory organs
What are the 2 main sections of the cranium
Neurocranium
Viscerocranium
What is the function of the neurocranium
What makes up the neurocranium
What are the 8 bones found here
Which ones are paired
Protects brain and brain stem
Forms
- skull cap
- cranial base
- intracranial region
Frontal
Ethmoidal (in eye socket)
Sphenoid (just in front of temple)
Occipital (back)
2x
Temporal
Parietal
What is the function of the viscerocranium
What makes up the viscerocranium
What are the 14 bones found here
Which ones are paired
Facial skeleton
Forms
- facial bones that support facial tissues
- upper and lower jaw
- nose, nasal cavity, orbits
Vomer (nasal septum)
Mandible (lower jaw)
2x Maxilla (upper jaw) Inf nasal concha Lacrimal (medial to eyes) Nasal (between eyes) Palatine (hard palate) Zygomatic (cheekbone)
What is the only movable joint in the skull
Mandible
temporomandibular joint
Name the 4 main brain regions
L and R cerebral hemispheres
-connected by corpus callosum
Diencephalon
Brainstem
- midbrain
- pons
- medulla oblongata (passes through foramen magnum)
Cerebellum
Name the 6 main brain lobes
What sulci separate the lobes
Frontal
Parietal
Occipital
Temporal
Cerebellum
Brainstem
Central sulcus
-separates the frontal and parietal
Lateral sulcus
-separates the temporal and frontal lobe
Describe the location of the 3 cranial fossa
What part of the brain is found in each fossa
Frontal
-ant cranial fossa
Temporal
-middle cranial fossa
Cerebellum
-post cranial fossa
What is the function of the foramen in the skull
How many cranial nerves are there
Which parts of the brain do they pass through
Allow cranial nerves to pass through to the head and neck
12 cranial nerves
Olfactory (I), optic (II) => cerebrum
Remaining 10 => brainstem
Name all 12 cranial nerves
I, olfactory II, optic III, oculomotor IV, trochlear V, trigeminal VI, abducens VII, facial VIII, vestibulocochlear IX, glossopharyngeal X, vagus XI, spinal accessory XII, hypoglossal
What foramen is associated with olfactory nerve I
Cribiformplate
What foramen is associated with optic nerve II
Optic canal
What foramen is associated with oculomotor III, trochlear IV, trigeminal V and abducens VI
Superior orbital fissure
Which 2 foramen are associated with only trigeminal V
Foramen rotundum
Foramen ovale
Which foramen is associated with facial VII, vestibulocochlear VIII
Internal acoustic meatus
Which foramen is associated with glossopharyngeal IX, vagus X and spinal accessory XI
Jugular foramen
Which foramen is associated with hypoglossal XII
Hypoglossal canal
What structure is associated with the foramen magnum
Medulla oblongata
Name the 3 layers of the meninges
What are their functions
Dura mater
- outermost layer
- collagen fibres = mechanical protective cover
- Sagittal sinus blood here
Arachnoid mater
- CSF found in subarachnoid
- delicate non vascular connective tissue
Pia mater (microscope needed)
- continuous with brain/cord surface
- supports brain blood supply
- forms choroid plexus that lines all ventricles (produces CSF) with ependymal cells
Name the layers of the head in order from the scalp to the white matter
What structure comes out of the arachnoid mater
What layers does it pierce through
Scalp Periosteum Skull Periosteal layer of dura mater Meningeal layer of dura mater Subdural space Arachnoid mater Subarachnoid space Pia mater Cerebral cortex White matter
Arachnoid villus, reabsorbs CSF
-passes through subdural space and meningeal layer of dura mater
What is the middle meningeal artery What does it branch off It is a terminal branch of what artery Describe the route of the middle meningeal What does it supply
Largest of 3 paired arteries supplying meninges
Branch of maxillary artery
Terminal branch of ext carotid artery
Foramen spinosum => under pterion => supplies dura mater and calvaria
What is the pterion
Where sutures of the frontal, parietal, sphenoid and temporal bones meet
What are the cerebral ventricles
What is their function
What are they lined by
Name the 4 ventricles
Communicating cavities that
- produce
- transport
- remove CSF via arachnoid granulations into systemic veins
Lined by ependymal cells => choroid plexus
2 lateral ventricles
3rd ventricle
4th ventricle
Describe the route of the CSF through the ventricles into the rest of the brain
Lateral ventricle => towards frontal horn => 3rd ventricle => under temporal horn => into cerebral aqueduct => 4th ventricle => exits ventricles via lateral and median apertures into subarachnoid space
Enter arachnoid villus => superior sagittal sinus
Describe the 4 main structures that come off the spinal cord
Nerve roots
Peripheral nerves
Conus medullaris
Cauda equina
Name the structures found in a cross section of the spinal cord
Afferents
Spinal nerve => dorsal root ganglia => dorsal root => dorsal horn
Efferents
Ventral horn => ventral root
Surrounded by dura mater, arachnoid mater and pia mater
Describe the ascending sensory pathway, leminiscal
1st order neurones
- carry sensory info from periphery in dorsal column => medulla oblongata
- T6 and above => fasciculus cuneatus => nucleus cuneatus
- Below T6 => fasciculus gracilis => nucleus gracilis
2nd order neurones
-Cuneate/gracilis nucleus => cross sides => contralateral medial reminisces => thalamus
3rd order neurones
-thalamus => ipsilateral primary sensory cortex
Describe the ascending sensory pathway, spinothalamic pathway
1st order neurones
-sensory from periphery => synapse in dorsal horn
2nd order neurones
-dorsal horn => cross sides => ant or lat spinothalamic tract => synapse in thalamus
3rd order neurones
-thalamus => ipsilateral primary sensory cortex
Name the 2 main ascending sensory pathways
Spinothalamic
Leminiscal
Name the 2 main descending voluntary pathways
Corticospinal
Corticobulbar
Describe the descending motor pathway, corticospinal pathway (voluntary)
Cerebrum receives inputs from
- primary motor cortex
- premotor cortex
- supplementary motor area
Neurons converge => medulla
2 tracts here
- lat CS tract => crosses over to contralateral side at level of medulla
- ant CS tract => crosses over to contralateral side at level of cervical/thoracic nerves
Synapse with motor neurones
Describe the structure of the fetal skull
- anterior
- posterior
- lateral
- posterior
Frontal bone has 2 parts
- anterior fontanelle => bregnum
- future coronal suture
Lateral
- lat ant and lat post fontanelle
- future squamous suture
Posterior
- posterior fontanelle => lambda
- future lambydoid suture
Superior
-future sagittal suture
