Midterm NeuroSci

skull

boney framework of the head, protects the brain

14 bones of face, 28 adult teeth, 8 cranial bones

cranium

portion of skull that encloses brain

suture lines

•Bones have fused – begin at 2 months and complete at 18 months

3 suture lines

•Coronal

•Sagittal

•Lambdoid

Fontanels

soft spots, located between the cranial bones of a fetus & newborn

Allows the skull to expand to accommodate the growing brain

stops being soft when brain stops growing in size

Meninges

•Located between the skull & brain, cover the spinal cord

•Form a seal around the CNS

•3 layers: Dura mater, Arachnoid mater, Pia mater

Dura mater-Meninges

-outermost meningeal layer

tough, thick membrane,

Dural Sinuses-large veins located above the frontal & parietal lobes (act like a circulatory system & allow cerebral vein to empty into them)

Cerebral veins receive CSF from the subarachnoid space

What is innervated by the nervous system in the skull

Dura mater

What causes headaches

constriction of meningeal membranes

Arachnoid mater-Meninges

•Middle meningeal layer – below subdural space

•Spider web – protects the brain, seal around the CNS

•Subarachnoid Space – holds CSF

•Cisterna Magna (Cerebellar Medullary Cistern) – used as a shunt placement in hydrocephalus

Pia Mater

•Deepest meningeal layer – located directly on the gyri & sulci of the brain/spinal cord

•Cranial Pia Mater

•Spinal Pia Mater

Blood brain barrier

•Meninges, protective glial cells, capillary beds of the brain

•Occurs along all neural capillaries

•Barrier acts as a wall that controls which molecules in the bloodstream will enter the CNS

•Oxygen, sugar, amino acids enter

•Ensures the brain will not be exposed to toxins (ie therapeutic guns)

Order of layers of skull & brain

skull-epidural space-dura mater-subdural space-arachnoid mater-subarachnoid space-pia mater- brain

ventricles

hallow spaces in the brain that contain CSF

Each ventricle has _ horns

3

Cerebrospinal fluid

•Clear, colorless fluid – nourishes the brain & spinal cord

•Pressure = constant circulatory pressure

•No neurologic mechanism that detects too much CSF and regulates its pressure & production

protects brain (shock absorption)

CSF & Hydrocephalus

•Abnormal accumulation of pressure & fluid → compression of neural tissue & enlargement of the ventricles

•Intracranial pressure & progressive enlargement of the head (childhood)

•Can be lethal in adulthood if not addressed

Hydrocephalus-infants

skull increases in size, cranial structures separate

compression of neural tissue

Treatment: caused by blockage→ shunt or tube, excessive production→ shunt placed from the 4th ventricle to abdomen to drain

can be treated in utero

Hydrocephalus-Adult

enlarges ventricles & rapid atrophy of neural tissue

increased intracranial pressure, headache & vomiting, cognitive deteration 

LIFE THREATENING

Treatment: surgical shunt placement (to abdomen), bypass of blockage, attempt to clear the fluid first, then shunt if indicated

Normal Pressure Hydrocephalus

•Develops in adulthood (50-70 years old)

•Arachnoid villi cannot absorb CSF

•Unsteady gait

•Progressive dementia

•Urinary incontinence

•Shunt placement

Gray matter

•Nucleus or groups of nuclei

•Dendrites

•Processing & decision making (interprets sensory & motor input)

White matter

•Myelin are glial cells that form fatty layers that appear white

•Communication highway (speeds up info rate)

3 pairs of funiculi: Anterior, lateral, dorsal

Glial cells

•Provide nutrition & physical support that maintains the structure integrity of neurons

•Support neuronal functions & have a role in synaptic communication

•Facilitates cell migration in development of the nervous system

Astrocytes

•Essential role in regulation of chemicals in the extracellular space

•Remove neurotransmitters from the synaptic cleft

•Control extracellular ion concentration to ensure proper neuronal function

Non- neuronal cells

•Microglia – eliminates debris from dead & degenerating neurons & glial cells – plays a role in remodeling of synaptic connections

•Ependymal Cells – line the ventricles of the brain & direct cell migration

CNS

Brain & spinal cord

PNS

Nerves branching from the brain and spinal cord to the  body

Includes all neural structures distal to the spinal nerves and the axons of cranial nerves outside the skull

PNS → CNS:

Sensory input (e.g., touch, pain, temperature) is sent to the CNS.

CNS → PNS

The CNS processes the input and sends motor output (e.g., move your hand) back through the PNS.

Afferent

Carry info from peripheral receptors towards the CNS

Efferent

carry info away from CNS

Endoneurium

separates individual axons

Perineurium

surrounds bundles of axons (fascicles)

Epineurium

encloses the entire nerve

Schwann cells

makes up myelin sheath

Somatic peripheral nerves –

sensory, autonomic, & motor axons

Cutaneous branches

supply skin & subcutaneous tissues (not purely sensory)

Muscular branches

supply muscle, tendons, & joints (not purely motor)

Cervical plexus

•Cutaneous sensory information from posterior scalp to clavicle, innervates the anterior neck muscles & diaphragm

•Phrenic nerve

Brachial Plexus

Upper limb innervated by Radial n., axillary n., ulnar n., median n., musculocutaneous n

Lumbar Plexus

Innervate skin and muscles of the anterior and medial thigh

Saphenous nerve innervates medial leg and foot

Sacral plexus

•Innervates posterior thigh and most of the leg and foot

•Contains parasympathetic axons in addition to the somatic axons (unlike the other plexuses)

Hyperalgesia

Increased sensitivity to pain

Dysesthesia

pain from normal sensations of light touch

paresthesia

feeling of pins and needles

allodynia

extreme sensitivity to touch

Autonomic Changes

•Lack of sweating, loss of sympathetic control of smooth muscle fibers (edema)

•Impotence, difficulty regulating blood pressure or heart rate, sweating, bowel/bladder functions

Motor Changes

Paresis (weakness) or paralysis

Fibrillation – spontaneous contraction of individual muscle fibers

Fasciculation – visible quick twitch of muscle fibers

Trophic Changes:

Nutritional changes → muscle atrophy, shiny skin, brittle nails, and thickening of subcutaneous tissues → ulceration of tissues, poor healing wounds/infection, neurogenic joint damage due to blood supply changes, loss of sensation, and lack of movement

Neuropathies

Pathology involving one or more peripheral nerves

Mononeuropathy

damage to single nerve

Radiculopathy

where nerve root originates in impinged

Plexopathy

damage to brachial/lumbar plexus

Polyneuropathy

bilateral damage to >1 peripheral nerve

sensory loss when compression occurs

conscious proprioception & discriminative touch → cold → fast pain/sharp stinging sensation → heat → slow pain or dull

After compression is resolves, sensation returns in

slow pain or dull → heat → fast pain/sharp stinging sensation → cold → conscious proprioception & discriminative touch

Traumatic Myelinopathy

¬Loss of myelin limited to the site of injury

¬Due to excessive pressure, stretch, vibration and/or friction

¬Entrapment – median, ulnar, radial, and fibular

Carpal Tunnel Syndrome 

¬Compression of median nerve in carpal tunnel

Vibration, wrist flexed/extended, repetitive flexion, genetics, pregnancy, endocrine/rheumatic diseases

pain, numbness, paresthesia: in thumb, index, third digit, & radial half of fourth digit

Severance

¬Division by excessive stretch or laceration

¬Attempt to build connection again; however, not always successful

¬Nerve conduction distal to injury may never return

Multiple Mononeuropathy

¬2 or more nerves in different parts of body (diabetes, vasculitis)

¬Restricts blood flow or weakens vessel walls resulting in ruptures

Polyneuropathy

¬Toxic, metabolic, autoimmune, or hereditary

¬Diabetes

¬Nutritional Deficiencies

¬Autoimmune diseases

Diabetic polyneuropathy (peripheral neuropathy)

all sizes of sensory axons are damaged à decreased sensation, pain, paresthesias, dysesthesias à damages joints of feet and foot ulcers

How to OT Diabetic polyneuropathy (peripheral neuropathy)?

long handled mirrors, foot wear, can recommend a nutritionist 

Guillain-Barre Syndrome

¬Acute inflammatory demyelinating polyradiculopathies

¬Weakness, areflexia/hyporeflexia in all four limbs

¬Rapid, distal to proximal

Charcot-Marie-Tooth Disease

¬Paresis of muscles distal to knee à foot drop, muscle atrophy

¬Progresses to affecting the hands

¬Onset à adolescence or young adulthood

Myasthenia Gravis

damages acetylcholine receptors at the NMJ – repeated use of muscle leads to weakness

Botulism

interference with the release of acetylcholine from the motor axon – acute and progressive weakness with loss of stretch reflexes

Electrodiagnostic Studies

Used to differentiate:

—myelopathy and axonopathy

—Upper motor neuron and lower motor neuron paresis (NCS is abnormal)

—Mononeuropathy vs. Polyneuropathy

—Local conduction block vs. Wallerian degeneration

EMG differentiates between nerve and muscle disorders (neuropathy vs. Myopathy)

Nerve regrowth rate

1mm per day, 1in per month

What happens when there is a problem with nerve regeneration?

¬unintentional movements (synkinesis)

¬Person can relearn muscle control to fix synkinesis

¬Can also occur with sensory system

OT interventions

education, edema management, movement, orthotics. modalities

Oh Oh Oh to touch And feel very good velvet AH

mnemonic for cranial nerves

Some say marry money but my big brother says brains matter more

Sensory & motor cranial nerve mnemonics

Olfactory nerve (CN I)

Smell; exits through the cribriform plate.

CN1

Olfactory nerve

Optic nerve (CN II)

Vision; afferent for pupillary and accommodation reflexes; exits via the optic canal.

CN II

Optic nerve

Oculomotor nerve (CN III)

Moves the eye, elevates the eyelid, constricts pupil, and accommodates lens; exits via superior orbital fissure.

CN III

Oculomotor nerve

Trochlear nerve (CNIV)

Moves eye medially and downward; innervates superior oblique; exits via superior orbital fissure.

Trochlear nerve

CN IV

Trigeminal nerve (CN V)

Somatosensation from the face; motor for chewing; exits via superior orbital fissure, foramen rotundum, foramen ovale

Trigeminal nerve

CN V

Abducens nerve (CN VI)

Abducts the eye; innervates lateral rectus; exits via superior orbital fissure

Abducens nerve

CN VI

Facial nerve (CN VII)

Facial expression; taste; lacrimation; salivation; exits via internal acoustic meatus and stylomastoid foramen.

Facial nerve

CN VII

Vestibulocochlear nerve (CN VIII)

Hearing and balance; exits via internal acoustic meatus

Vestibulocochlear nerve

CN VIII

Glossopharyngeal nerve (CN IX)

Sensation from pharynx and posterior tongue; gag/swallow reflexes; taste; exits jugular foramen

Glossopharyngeal nerve

CN IX

Vagus nerve (CN X)

Sensation from pharynx/larynx; parasympathetic to viscera; controls swallowing/speech; exits jugular foramen

Vagus nerve

CN X

Spinal accessory nerve (CN XI)

Elevates shoulders and turns head; exits jugular foramen

Spinal accessory nerve

CN XI

Hypoglossal nerve (CN XII)

Moves the tongue; exits via the hypoglossal canal

Hypoglossal nerve

CN XII

Cervical Plexus

Cutaneous innervation posterior scalp → clavicle + motor innervation of neck muscles & diaphragm

Brachial Plexus

becomes the radial, axillary, ulnar, median & musculocutaneous nerves, innervated the entire UE

Plexus

innervates the skin & musculature of the anterior & medial thigh. The sensory branch innervates the medial leg and foor