Brain and skull Flashcards
number of skull bones
- 28:
- 8 cranium
- 14 facial
- 6 ear
external bones of face
- 2 zygomatic (cheek bones)
- 2 maxillary (each side of nose)
- 1 mandible (jaw)
- 2 nasal (base of nose)
suture
- joints between cranial bones
- interdigitate so minimal movement
8 bones of skull (7 external, 1 internal)
- frontal (1 at front)
- 2 parietal (1 on either side on top in middle)
- occipital (1 at back)
- 2 temporal (1 on either side at bottom of cranium)
- sphenoid (1 directly behind face spanning both sides)
- ethmoid bone (internal)
3 sutures
- coronal suture - frontal and parietal
- lambdoidal suture - occipital and parietal
- squamous suture - temporal and parietal
fontanelle
- gaps between sutures
- not joined at birth to allow growth
3 meninges
1) dura mater 2) arachnoid 3) pia mater
dura mater
- Outer-most layer of meninges
- Dense and fibrous – tough
- Two layers - Inner layer forms the dural reflections
- Space between the layers forms venous sinuses
3 Dural reflections
- Falx cerebri - separates cerebral hemispheres - median plane
- Falx cerebelli - separates cerebellar hemispheres - median plane
- Tentorium cerebelli - separates the cerebrum from the cerebellum - horizontal plane
venous sinus
- Form between outer and inner layers
- Venous drainage from the brain
arachnoid
- Layer beneath the dura mater
- Contains blood vessels
- Does not extend into sulci (‘valleys’)
- sits of spidery legs creating sub-arachnoid space
Subarachnoid space
- Between the arachnoid and the pia mater
- Filled with cerebrospinal fluid (CSF)
Arachnoid granulations
- Perforate the dura
- Transport “old” CSF from subarachnoid space into venous sinus
Pia mater
- Transparent and delicate
- Blood vessels in arachnoid sit on top of pia mater
- Adheres to brain and follows gyri and sulci
meninges of spinal cord
cover spinal cord is same way as brain
ventricular system
- Network of interconnected “spaces” within the brain
- Filled with cerebrospinal fluid (CSF), which nourishes and protects the brain
- CSF is produced by the choroid plexus, which lines the ventricles
CSF
nourishes and protects brain
choroid plexus
produces CSF
ventricular system
Circulation of the CerebroSpinal Fluid
- Circulates through ventricles and subarachnoid space of the brain and spinal cord
- Route:
- Lateral ventricle
- 3rd ventricle
- cerebral aqueduct
- 4th ventricle
- subarachnoid space
hydrocephalus
- caused by abnormal accumulation of CSF in the ventricles of the brain
- Leads to increased intracranial pressure inside the skull,
- Progressive enlargement of the head,
- Other symptoms include convulsion, tunnel vision, mental disability.
lobes, sulci and gyri of brain
function of occipital lobe
vision
function of parietal lobe
sensory
function of temporal lobe
memory and hearing
function of posterior front lobe
motor
function of anterior frontal lobe
pre-frontal cortex
function of pre-motor cortex
planning of movement
function of primary motor cortex (post-central gyrus)
execution of movement
function of pre-frontal cortex and effect of damage
- Decision making
- Anticipating consequences of our actions
- Emotion
- Damage can change “who we are”
- Development may be altered by alcohol
- Involved in mental illnesses that change who we are, e.g. schizophrenia
division of brain
brainstem anatomy ventral view
3 types of white matter in brain
- commissural tracts
- projections tracts
- association tracts
commissural tracts
- Axons cross from side to side; go both ways.
- Example: Corpus callosum
projection tracts
- axons extend between cortex and other CNS areas
- e.g. corticospinal tract
association tracts
- axons on same side within cerebral cortex
- communication between brain areas
- Example: communication between motor cortex and premotor cortex
Primary motor cortex organisation
Specific regions of the motor cortex control specific regions of the body
corticospinal tract
- descending somatic motor tract
- Controls activity of somatic (efferent) motor neuron
- Cell bodies (EFFERENT) in primary motor cortex
- Most fibres cross to opposite side in medulla oblongata
- Axons descend until spinal cord
- Synapse in spinal cord (ventral horn)
Parietal lobe function
- Somatosensory
- Integration of multiple types of sensory information
- Association
Simple somatic sensory (afferent) pathway
Primary somatosensory cortex
• Specific regions of the somatosensory cortex receive sensory information
integration between motor and sensory systems - role of cerebellum
- Motor cortex initiates movement
- Copy of instructions sent to cerebellum
- Some sensory information goes to the cerebellum = information about actual movement
- Cerebellum compares this info with copy of motor output
- “Adjusts” motor output for COORDINATION
- The cerebellum coordinates movement, guided by sensory feedback.
5 nuclei of basal ganglia
- caudate
- putamen
- globus pallidus
- subthalamic nucleus
- substantia nigra
basal ganglia function
- In a brain circuit that also involves other structures
- Select an appropriate movement for a given situation
- Initiate movement
- Terminate movement
5 nuclei of Basal Ganglia
- caudate
- putamen
- globus pallidus
- subthalamic nucleus
- substantia nigra
function of basal ganglia
- selects an appropriate movement for a given situation
- initiate movement
- terminate movement
