HUMB C9

Spinal cord Regions (superior to inferior)

Cervical, Thoracic, Lumbar, Sacral, Coccygeal

Spinal nerves

31 pairs:

8 cervical

12 thoracic

5 lumbar

5 sacral

1 coccygeal

vetebral bones

30 bones:

7 cervical because C8 nerve exits superior to T1 vetebra

12 thoracic

5 lumbar

5 sacral

1 coccygeal

Spinal nerve and vertebra relative position

7 cervical nerves exit superior to their corresponding vertebra

C8 nerve exits superior to T1 vetebra

All nerves inferior to C8 nerve exit inferior to their corresponding vertebra

enlargements

Thicker areas of spinal cord, located where plexuses are

2 - Cervical and lumbosacral

Conus medullaris

Cone-shaped area inferior to lumbosacral enlargement where spinal cord tapers off and ends

Lumbar and sacral nerves exit below

cauda equina

bundle of lumbar, sacral, and coccygeal nerve roots that descend inferior to conus medullaris, through vetebral canal providing dual innervation to lower limbs and pelvic area

Meninges - Def and functions

Connective tissue surrounding brain and spinal cord

Protection, contains CSF, form partitions inside skull

meninges layers

Outer: epidural space - adipose tissue

Dura mater - thick, strong

subdural space

Arachnoid mater

Subarachnoid space – CSF and blood vessels

Inner: Pia mater - thin covering with many small blood vessels

Nerve coverings

3 layers of CT

Endoneurium– surrounds each axon

Perineurium– surrounds a fascicle (bunch of axons)

Epineurium – surrounds several fascicles

Brain regions

Forebrain: Cerebrum and Diencephalon

Midbrain

Hindbrain: Pons, Medulla oblongata, and Cerebellum

Which regions make up brainstem?

midbrain, pons, and medulla oblongata

medulla oblongata

3cm long

Connects to spinal cord

White matter forms motor and sensory tracts

autonomic reflexes (coughing, vomiting, swallowing), cardiovascular, and respiratory centre

Pons

white matter forms longitudinal (sends info b/w brain and spinal cord) and transverse (sends info b/w cerebrum and cerebellum) tracts

sleep and respiratory centre

Midbrain

Receives and integrates visual, auditory, and tactile sensory input

Responds by orienting head and eyes

Cerebellum

communicates with cerebrum (via transverse tracts) to control locomotion (movement)

Fine motor, posture, balance control

Diencephalon - Thalamus

Paired structure

Cluster of nuclei (grey matter)

Sensory relay centre

Influences mood and strong emotion (fear, rage)

Diencephalon - Hypothalamus

Inferior to thalamus

Cluster of nuclei (grey matter)

Controls endocrine system (Infundibulum connects to pituitary gland)

behaviour, autonomic muscle control, body temp, food and water intake, sexual development

Gyri, Sulci, and Fissures

Gyri (singular - gyrus): elevated tissue or fold that increases surface area, allowing more neurons to fit within brain

In between gyri are sulci (singlular - sulcus): folds

Fissure is a deep sulcus

Cerebrum landmarks

longitudinal fissure seperates right and left hemispheres

lateral fissure seperates frontal and parietal lobes from temporal lobe, underneath is insular lobe

central sulcus seperates frontal lobe from parietal lobe

Cerebrum lobes

Frontal, parietal, occipital, temporal, insular

Cerebrum - pre and post central gyri

Pre-central gyrus: In frontal lobe, anterior to central sulcus, primary somatic motor cortex

Post-central gyrus: In parietal lobe, posterior to central sulcus, primary somatic sensory cortex

Cerebrum - Frontal lobe

pre-central gyrus

motor function, motivation, planning, mood regulation, sense of smell

Cerebrum - Parietal lobe

post-central gyrus

receives and evaluates sensory info (pressure, temp), not special senses (smell, hearing, vision, taste)

Cerebrum - Occipital Lobe

receives and integrates visual input

Cerebrum - Temporal Lobe

receives and evaluates input for smell and hearing

memory

Cerebrum - Insular Lobe/Insula

receives and evaluates taste information

Cerebral Cortex

consciousness, memory, reasoning

Corpus callosum

Biggest commisural fibers that transmits information between hemispheres

Located in limbic system

Brain Nucleus/Nuclei

Clusters of neuron somas

Limbic system

Deep area running through medial parts of both hemispheres and parts of diencephalon

Memory, motivation, emotion, learning

Influences autonomic and endocrine systems

Meninges 1

Skull

Dura mater: periosteal dura (superficial), meningeal dura continuous with dura mater of spinal cord (deep)

Dural venous sinus: space between periosteal and meningeal dura, contain veins

*In some areas periosteal and meningeal dura are fused

falx cerebri

Main dural fold extending into a fissure

limits excessive movement of brain in cranium

Meninges 2

Subdural potential space: very small, filled serous fluid

Arachnoid mater

Subarchnoid space with blood vessels and CSF

Pia mater directly attached to cerebrum

Ventricles

4 continuous ventricles - 2 lateral (1 in each hemisphere) continuous with 3rd then 4th ventricles

4th ventricle continuous with spinal cord

All have a choroid plexus that produces CSF

Lined with ependymal cells - circulate CSF

Cerebrospinal fluid (CSF)

Most produced by choroid plexuses, some by blood

Protects and cushions brain and spinal cord

Allows brain to float to reduce weight

Similar to blood serum, without most of proteins

Cranial nerves

12 pairs

9 pairs connect to brainstem

can have single or multi function (parasympathetic, somatic motor, sensory)

Autonomic NS Divisions

sympathetic (fight and flight) and parasympathetic (rest and digest)

both maintain homeostasis by adjusting body functions

Sympathetic has greater influence during stress and physical activity

Parasympathetic has greater influence during resting

Location of ANS (S + PS) somas in spinal cord

Sympathetic preganglionic neuron somas in thoracolumbar division in lateral horn of grey matter

Parasympathetic preganglion neuron somas in craniosacral division in lateral horn of grey matter

Both Sympathetic and Parasympathetic postganglionic neuron somas in autonomic ganglia (outside grey matter)

Dual ANS Innervation

Structure/organ has both sympathetic and parasymathetic neurons

Not all organs have dual innervation

ANS Regulation

Sensory receptors

Spinal cord reflex centres - defecation, urination

Brainstem reflex centres - pupil dilation, coughing, digestive activities, heart rate, respiration

Hypothalamus - influences hormonal release from pituitary galnd, body temp

Cerebrum and limbic system - thoughts and emotions influence ANS through hypothalamus