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