Cns Anatomy Slides

Brain Anatomy Slides courtesy of Dr. Maria Rubio

General Rule: The functional and anatomical organization of

sensory processing networks is hierarchical

1st order neuron

3rd order neuron

2nd order neuron

Figure 13-2

Gross Anatomy of the Spinal Cord

Figure 16-1 M

Spinal Nerves:

� 8 Cervical nerves

� Neck, shoulder, arms and hands

� 12 Thoracic nerves

� Shoulders, chest, and upper abdomen

� 5 lumbar nerves

� Lower abdomen, hips and legs

� 5 sacral nerves

� Genitals and lower digestive tract

Gross Anatomy of the Spinal Cord Cross Section:

� Gray matter� Gray due to cell bodies

� In CNS, gray matter also = synapses

� White Matter� White due to myelin; =

axons (both myelinated and unmyelinated)

� Dorsal Horn

� Ventral Horn

� Ventral Root

� Dorsal Root� Cell bodies of unipolar

sensory neurons

� No synapses

� Dorsal Root Ganglion

Sectional

Anatomy of the

Spinal Cord

Figure 6-41 V; 16.3M

See 16.4M

Note functional organization of gray matter

Fiber Tracts: Ascending (Sensory) Tracts

� Dorsal Columns

� Fasciculus cuneatus

� Fasciculus gracilis

� Anterolateral columns

� E.g., spinothalamic tracts

� Spinocerebellar tracts

Note functional organization of WHITE

matter

Fiber Tracts: Descending (Motor) Tracts

� Ventromedial System

� Reticulospinal

� Vestibulospinal

� Tectospinal

� Anterior Corticospinal

� Dorsolateral System

� Rubrospinal

� Lateral Corticospinal

Pyramidal; extrapyramidalterminology is outdated!

Spinal NervesPeripheral Nerve Structure

Dermatomes

Figure 16.6 M

Nerve Plexuses� A network of

interweaving anterior rami of spinal nerves

� Rami (pl.) ramus –primary division of a nerve or blood vessel

� Cervical plexus

� Brachial plexus

� Lumbar plexus

� Sacral plexus

Cervical Plexus

� C1 – C4

� Innervates neck (sensory and motor)

� Phrenic nerve (C3 - 4)

� Innervates diaphragm (so you can breathe!)

Figure 16.8 M

Brachial Plexus� C5 – T1

� Sensory/motor innervation of upper extremity

� More complex than cervical plexuses

� Anterior rami

� Trunks

� Divisions

� Cords

Figure 16.9 M

Lumbar Plexus� L1 – L4

� Supply lower limb of each side

� Less complex than brachial plexus

Figure 16.10 M

Sacral Plexus� L4 – S4

� Supply gluteal region, plevis, perineum, and lower limb of each side

� Together with Lumbar plexus as lumbosacral plexus

Figure 16.11 M

Components of Reflex Arc

See also Figure 16.12 M

Example of Deep Tendon Reflex

Patellar tendon (“knee jerk”) reflexClinical usefulness

Monosynaptic (Knee Jerk) and Disynaptic

(Flexor Withdrawal) Reflexes

Figure 16.13 M

�Clinical usefulness of reflexes –see table 16.6 M

�Muscle tone

Slides courtesy of Dr. Maria Rubio

Sagittal Plane

Coronal Plane

Posterior View

Brainstem

� Brainstem � Medulla

� Pons

� Midbran

� Rigidly programmed, automatic behaviors

� Medulla

• Centers for cardiovascular and respiratory regulation

• Cranial nerve nuclei

• Reticular formationMedulla

Pons

Pons �

• Cranial nerve nuclei, tracts

• Reticular formation

Midbrain

� Midbrain

• Superior Colliculus

• Eye / Head orientation movements

• Inferior Colliculus

• Tracts, nuclei

• Reticular formation

RETICULAR FORMATION ����

• > 100 Nuclei

• Extends throughout brainstem

• Receives info from all over brain

• Projects throughout brain

Cerebellar peduncles

• Receives visual, vestibular, proprioceptive input

• spinocerebellar tracts

• Functions include coordination

Cerebellum

Figure 15-22 M

Posterior View

(Brainstem and) DiencephalonDiencephalon

DiencephalonEpithalamus

Thalamus

• Sensory relay center

Hypothalamus

• “Homeostasis”

ThalamusSagittal

Coronal

HypothalamusSagittal

Coronal

Autonomic Functions

Superior View Anterior View

Posterior View

Lateral View

Ventral View

Cerebral Hemispheres

Superior View

Anterior View

Posterior View

Cortex: Correlate Lobes with Function

Figure 15-1 M

� Frontal� Motor, speech, personality, emotion

� Frontal lobotomies� Parietal

� Somatosensory cortex, voluntary movement

� Occipital� Vision

� Temporal� Hearing, balance, visual processing

ridges

Shallow separation

Lateral View

White Fiber Tracts� Projection fibers

� Commisural fibers

� Association fibers

Frontal

Human Brain: coronal sections

Caudal

Basal Ganglia� Nuclei important in motor control

� Caudate, putamen, globuspallidus

� Subthalamic nuclei, substantia nigra

Internal Capsule

� Between putamen-globuspallidus and thalamus

� Major projection of fibers to/from cortex

� Common CVA (stroke) site

Rhinencephalon� Phylogeneticallyancient cortex� Olfactory bulb + tract

� Fornix

� Limbic system� Amygdala

� Hippocampus

Limbic System

� Emotional brain� Shape of a ring (around diencephalon)� Cingulate gyrus� Parahippocampalgyrus

� Hippocampus� Amygdala� Olfactory bulbs� Fornix� Diencephalon nuclei

Cerebral Hemispheres: Frontal section at a:Gray matter (cell bodies – in CNS, also SYNAPSES)White matter (axons)

Corpus Callosum: connects cerebral hemispheres (with commisural fibers)

Figure 15-3 M

Cerebellum and Brainstem (section at b):Gray matter (cell bodies + synapses)White matter (axons)

Figure 15-3 M

Medulla (lower brainstem; section at c):Gray matter (cell bodies + synapses)White matter (axons)

Figure 15-3 M

Spinal Cord (section at d):Gray matter (cell bodies + synapses)White matter (axons)

Figure 15-3 M

Ventral View

Cranial Nerves

See lecture outline for functions of each.

Research Martin StynerVentricles (with CSF)The brain is a hollow organ

Brain Ventricles

Figure 15-6 M

Cranial Meninges

Figure 15-5 M

Dura mater ArachnoidArachnoidPia mater

Cranial Meninges

Figure 13–3

Spinal Meninges

Figure 16.2 M

Cerebral Spinal Fluid (CSF)� Surrounds brain & spinal

cord; circulates through ventricles

� Cushions; protection

� Formed in choroid plexus by ependymal cells

� Blood-brain barrier limits the flow of solutes into CSF

� Materials which easily pass across the BBB:

� Glucose, AAs, certain ions, fatty acids, nicotine, CO, CO2

� BBB restricts these materials:

� Blood, wastes (e.g. urea), proteins, K+ ions

Recall role of ASTROCYTES and TIGHT JUNCTIONS in forming BBB

See also Figure 15-8 M

Vascularization

Internal Carotid A.Vertebral A.

Basilar a

Posterior

Cerebral A.

Anterior

Cerebral A.

Middle

Cerebral A.

The major arterial supply to the brain

Circle of Williscollateral circulation

Posterior cerebral art.

Middle cerebral art.Anterior cerebral art.