7 - Anatomy of the CNS and Scalp Flashcards
Where are the dorsal and ventral parts of the human brain?
- Brain is flexed at the midbrain so in front of this line is ventral, behind is dorsal
What is the embryological origin of the nervous system?
- From ectoderm
- Neuroectoderm tube above notochord in the mesoderm
Label the parts of the brain stem and what their functions are.
Midbrain: eye movements and reflex responses to sound and vision, e.g run from tiger
Pons: feeding and sleep. Trigeminal through here. Suckling reflex
Medulla: cardiovascular and respiratory centres. autonomic functions like sneezing. motor and sensory neurones from mid brain travel through pyramids and decussate
What is the diencephalon?
Caudal part of forebrain, containing epithalamus, thalamus, hypothalamus, ventral thalamus third ventricle.
Relays sensory information between brain regions and controls autonomic functions of the PNS. It connects structures of the endocrine system with the nervous system and works with the limbic system structures to generate and manage emotions and memories
Label the fore, mid and hind brain.
Label this inferior view of the brain, particularly the brainstem.
What is the clinical relevance of decussation in the medullary pyramids?
- Weakness in one side of the body typically correlates to issue with opposite side of the brain to the weakness
What are the following structures and what are the main examples of each in the brain
- Sulcus
- Gyrus
- Fissure
- Sylvian Fissure also known as lateral fissure!
- Sulci and Fissures split brain into lobes
Gyri (singular: gyrus) are the folds or bumps in the brain and sulci (singular: sulcus) are the indentations or grooves
What is the relevance of the central sulcus?
- Structures in front tend to have motor function
- Structures behind tend to have sensory function
Where are the different lobes of the brain and what are their functions?
- Frontal (front of central sulcus): motor function, speech, higher cognition and behavioural control
- Parietal (behind central sulcus): sensation, spatial awareness
- Temporal (behind lateral fissure): memories, smell, hearing, emotional processing
- Occipital (parietooccipital sulcus): vision
- Cerebellum: motor learning and coordination e.g remembering to ride a bike. Motor as used to be at front
What are some iportant structures labelled on the inferior aspect of the brain here.
- Optic chiasm: site where fibres in visual system cross
- Uncus (medial temporal lobe): part of temporal lobe that can herniate and compress the midbrain, especially CN3. Also olfactory centre
Medullary pyramids: location of descending motor fibres
What structures are highlighted on the CT scan and what is their function?
- Corpus callosum: fibres that connect the two hemispheres so they can communicat (alien hand syndrome)
- Thalamus: sensory relay station going to sensory cortex
- Hypothalamus: homeostasis
What are the layers of the scalp?
What are the dermatomes of the head and neck?
What is the arterial supply to the scalp?
This baby had a traumatic labour and has a subperiosteal haematoma, will his brain be affected?
Between periosteum and bone, won’t affect brain as extracranial
A young boy fell off of his bike and hit his head, what injury has occured?
Haematoma in the dense connective tissue as this is where most of the vessels are found. Restricted as cannot track so lumps out into the epidermis and dermis - LOCALISED LUMP
What would happen if there was a laceration to the scalp down to the dense connective tissue?
- Lots of bleeding as the blood vessels walls are adhered to the connective tissue so they cannot vasoconstrict.
- Apply pressure, clean to prevent infection and glue
- Hard to get deep infection as infections cannot track so will be localised
What would happen if there was a laceration to the scalp down to the loose connective tissue?
- Gaping due to cutting of occipitofrontalis aponeurosis so muscles would pull in opposite direction
- Risk of intracranial infection, e.g meningitis, as bacteria can track through emissary veins into the skull
- Blood can track all over scalp to insertions of occipitofrontalis leading to periorbital bruising and under hair bruising.
- Clean and suture
What are some differentials to consider if a lady presented like this?
- Damage to loose connective tissue of scalp so bleeding under aponeurosis
- Basilar fracture of skull
- Orbital fracture
- Find out mechanism of injury and CT
If a man presented with this, what could be some differentials?
- Dense connective tissue haematoma in the scalp
- Sebaceous cyst from the dermis
What is the cutaneous innervation to the scalp?
What is cortical homunculus?
Do cranial nerves decussate? And where do they normally decussate?
- No apart from CN2, 4, 7 and 12
- Decussation of neurons usually occurs at medullary pyramids of medulla oblongata
- Explains why strokes in one side affect muscles of opposite side
Where is the cerebrum and the forebrain?
- Forebrain: cerebrum and diencephalon
How do you split the brain into dorsal, ventral, rostral and caudal?
Where are the cerebral peduncles and what are their functions?
Front of the midbrain and pons and contain the large ascending (sensory) and descending (motor) nerve tracts that run to and from the cerebrum from the pons
Where is the location of the following cortices:
- Primary motor
- Primary somatosensory
- Primary visual
- Primary auditory
- Primary olfactory
Primary olfactory just below auditory
Where is the parieto-occipital sulcus?
Label the different parts of the diencephalon.
Thalamus involved in relaying sensory information
Label the following parts of the cerebellum:
- hemispheres
- folia
- vermis
- tonsils
- cerebellar peduncles
- Peduncles attach cerebellum to brain stem
Where is the septum pellucidum and what is it’s relevance?
Separates the two lateral ventricles
Where are the ventricles of the brain and what do they contain?
Contain CSF which appears black on CT
Where is the pituitary gland and stalk?
Below hypothalamus
