Brain dissection Flashcards
Rostral
At front, by nose
Causal
Posterior brain - towards tail
Dorsal
Back of animal
Ventral
Bottom/abdomen of animal
Coronal plane
Divides brain into rostral/anterior and caudal/posterior sections
Sagittal planes
Divides brain into lateral and medial
What are the meninges?
3 layers forming a protective covering
What are the layers of the meninges (superficial going in)
Dura mater
Arachnoid mater
Pia mater
What is the dura mater divided into?
Meningeal layer and periosteal layer (closer to bone)
Where is the tentorium cerebelli?
Runs on border of middle and posterior cranial fossa, sits between occipital lobe (cerebral hemispheres) and cerebellum
Where is the optic chiasma?
Forms cross on bottom of brain
Characteristics of epidural hematoma
Skull fracture, young patients, middle meningeal artery, arterial, bright red blood, unilateral
Tend to lose consciousness after a few hours
Hallmark of epidural hematoma
Biconvex, bright white area
Blood pushes brain to other side
Characteristics of subdural bleeding
- Much more diverse causes
- Sudden change of velocity of the head
- Usually last tributaries are affected
Hallmark of subdural bleeding
Sickle shaped area
Symptoms of subarachnoid bleed
Thunderclap headache
How to detect subarachnoid bleed
Blood enters CSF so can be detected during Lp
What is inter-ventricular bleeding?
Bleeding inside brain - increased ICP and shifting of brain
Characteristics of a brain hernia
- Raised ICP
- Supratentorial herniation: uncal (transentorial), central, cingulate (subfalcine/transfalcine), transcalvarial
- Infratentorial herniation: upwards (upward cerebellar or upward transtentorial)
Symptoms of meningitis
Fever, headache, neck stiffness, confusion, unconsciousness, vomiting, inability to tolerate light
What is meningitis?
- Acute inflammation of protective membranes covering brain and spinal cord, collectively known as meninges
What is bacterial meningitis?
Low glucose in CSF because bacteria using glucose
How to reduce ICP
Blood escapes through tentorium notch on tentorium membrane
Veins between layers that drain brain
What is the confluence of veins that drain brain?
Superior sagittal sinus
Characteristics of arachnoid mater
Very thin - like spider web
CSF found within
If arteries burst and released into sub arachnoid mater, RBCs diluted with CSF
What is essentially a stroke?
Leak of blood into CSF
What is a haematoma?
Solid blood
What is a haemorrhage?
Fresh blood
Symptoms of enlarged pituitary gland
Bitemporal hemanopia
Function of corpus callosum
Connects L and R side of brain using myelinated axons
Function of frontal lobe
Cognitive functions, control of voluntary movement/activity
Function of parietal lobe
Senses
Function of occipital lobe
Vision
Function of temporal lobe
Memories, integrating them with taste, sound, sight, touch
What causes central diabetes insipidus?
Deficiency of vasopressin
What causes gitanticism and acromegaly?
Excess of growth hormone in childhood and adulthood respectively
What causes hypothyroidism?
Deficiency of TSH
What is hyperpituitarism?
Increased secretion of 1+ hormones produced by pituitary gland
What is hypopituitarism?
Decreased secretion of 1+ hormones normally produced by pituitary gland
What ispanhypopituitarism?
Decreased secretion of most pituitary hormones
What are pituitary adenomas?
Non-cancerous tumours occurring in pituitary glands
Function of midbrain
Vision, hearing, motor control, sleep and wakefulness, arousal, temperature regulation
Function of pons
Sleep, respiration, swallowing, bladder regulation, hearing, equilibrium, taste, eye movement, facial expressions
Function of medulla
Involuntary functions (e.g. vomiting, sneezing etc), cardiac, respiratory, vomiting and vasomotor centers - deals with autonomic functions too
What is brainstem death?
Absence of cough/gag/corneal/vestibulo-cochlear. reflexes
Function of cerebellum
Execution and monitoring of commands from motor cortex
What does DANISH stand for - cerebellum
- D: dysdiadochokinesis
- A: ataxia
- N: nystagmus
- I: intention tremor
- S: slurred speech
- H: heel-shin test positivity
Function of 4th ventricle
Contains CSF - continuous with cerebral aqueduct - CSF enters sub-arachnoid space from here
Function of foramen of Monro
From lateral to 3rd ventricle
Function of cerebral aqueduct (Sylvius)
3rd to 4th ventricle
Function of median aperture (Magendie)
4th ventricle to subarachnoid space via cisterns magna
Function of lateral apertures (Luschka)
4th ventricle to sub arachnoid space vis great cerebral vein
Function of superior colliculus
Orientate animal, particularly eye movement
Function of inferior colliculus
Auditory center, signal integration, frequency recognition, pitch discrimination
Characteristics of grey matter
- Largely made out of cell bodies of neurons
- Fully develops when person reaches 25
- Conducts, processes and sends information to various parts of the body
- 40% of brain
Characteristics of white matter
- Myelinated axons
- Myelin has a lot of fat - appears white
- 60% of brain
- Bundles connect various grey matter areas
- Develops throughout 20s and peaks in middle age
- Interprets information from various parts of the body
- Raising body temperature makes white matter translucent - melts it
- Cerebellum is opposite of spinal cord in terms of grey and white matter
Sequence of ventricles
Lateral - 3rd - aqueduct - 4th
Escapes from 4th to travel to larger ventricles in sub arachnoid space