Neuroanatomy
cerebral security
- the brain is inclosed in thick bones and the spinal cord is protected with many interlocking bones - brain contains meningeal coverings
damage to one artery of the brain
- the other arteries will pick up the slack - another element of cerebral security (genetic/trauma/poor dietary choices - buildup of fatty tissue)
dura mater
- thick - double layer - enclosing brain in a loose sac
arachnoid mater
- very thin sheet of delicate tissue - follows contours of the brain
3 main arteries of the brain
-Anterior cerebral artery (ACA) - irrigates medial and dorsal -Middle cerebral artery (MCA) - irrigates lateral -Posterior cerebral artery (PCA) - irrigates ventral and posterior
Spinal Cord nerves
cervical, thoracic, lumbar, sacral
neuroanatomy planes/direction
table on ipad
nuclei
clusters of cell bodies in the CNS
ganglia
clusters of cell bodies in the PNS
cerebral aqueduct
connects the third and fourth ventricles
gray matter
consists mainly of neuronal cell bodies (nuclei) and lacks myelinated axons.
parasympathetic derived from
mostly from cranial nerves (vagus, facial, oculomotor) connects with parasympathetic ganglia near the site of the organ
white matter
myelinated axons
neuron types
sensory, motor, interneurons
pain and temp receptors (reflex)
produce flexion - mild = only distal part will withdraw - strong = size of movement increases
Modern Brain Mappers
- Allen institute for Brain Science (Seattle) - Started by Paul Allen - Wanted to build tools that could be used by the entire scientific community
Where is the BBB absent?
- area postrema (located in medulla) - can serve to protect CNS because injected toxin can be detected and vomited
ANS
- balances body's internal organs - parasympathetic nerves (rest and digest) - sympathetic nerves (fight and flight)
circle of willis
- brain receives blood supply from 2 internal carotid arteries and 2 vertebral arteries - they connect at base of the brain - branch off into several smaller arteries that go to brainstem and cerebellum - give rise to 3 arteries that go to forebrain
Canadian Perspective SCI
- by 2030, estimated to have 121,000 SCI injuries (expected increase!! incremental over time) - traumatic spinal cord injuries are most common in males from 20-29
Types of SCI injuries
- complete: spinal cord is sufficiently damaged across its width; complete loss of sensation/movement below level - incomplete: spreads across pat of spinal cord; can have some sensation/movement control below level
Blood Brain barrier
- conceptual - tightly packed layer of cells that can block passage of large molecules
somatic nervous system
- consists of spinal and cranial nerves - transmits sensory information to CNS (vision, hearing, pain, temp, touch, position/movement of body parts) - produces movement in response
Cervical Spine injury
- damage from neck down (swallowing, speech, movement of arms and hands) - effects in addition to loss of function in thoracic/lumbar/sacral regions
types of glial cells
- ependymal (line ventricles and make CSF) - astrocyte (BBB, support and nutrition) - microglia (fight infection, remove debris) - oligodendroglia (insulate neurons in CNS) - schwann cells (insulate sensory and motor neurons in PNS)
inner pia mater
- moderately tough - clings to surface of the brain
cranial nerve organization
- sensory function = posterior - motor functions = anterior
ipsilateral, contralateral, proximal
- structures on same side - structures on opposite side - structure close to one another
dermatome
Area of skin supplied by a single spinal nerve
nerves
Bundles of neuron fibers (axons) that are routed together in the PNS
Sacral spine injury
Impairs areas of bladder and bowel control, affecting daily life and independence Sexual function is also impeded
Thoracic spine injury
Injury in this area causes difficulties in breathing and digestion In addition to loss of function in the lumbar and sacral regions
Lumbar spine injury
Injury in this area impairs movement in legs and feet Loss of function in addition to loss of function in sacral region
Paraplegic vs quadriplegic
Paraplegics can move their arms and hands. Quadriplegia is paralysis to some degree in all four limbs.
hydrocephalus
abnormal accumulation of fluid (CSF) in the brain - if channels are blocked - builds up
tracts
bundles of axons in the CNS
role of the 4 brain ventricles
cushion from shock and pressure by CSF that circulates in the ventricles, spinal column, subarachnoid space
meninges of the brain
dura mater, arachnoid mater, pia mater
Bell-Magendie Law
entering dorsal roots carry sensory information and exiting ventral roots carry motor information
sympathetic derived from
forms sympathetic ganglia running parallel to spinal cord (synapse close to spinal cord and then go to target organs)
reticular matter
intermingling of white and gray matter
precentral gyrus
primary motor cortex
fine touch and muscle receptors (reflex)
produce extension - maintains contact with a surface
size of spinal nerve fibers
typically pain and temp fibers are smaller touch and muscle are larger
problem with BBB
when we want medication to gain access to cells in the brain