Intro to Neurology

Central Nervous System

• Includes the brain, spinal cord, and covered meninges

• Starts in the CNS and ends in the CNS

• Upper motor nerves

Peripheral Nervous System

• Includes cranial nerves and spinal nerves

• Lower motor neurons

• Starts in CNS and ends in the PNS

Somatic Nervous system

• Subdivision of the peripheral nervous system

• Innervates structures of the body such as muscles, skin, and mucous membranes

Autonomic Nervous System (Visceral)

• Subdivision of the peripheral nervous system that controls involuntary bodily functions such as heart rate, digestion, and respiratory rate.

• Controls smooth muscles and glands of internal organs

• Returns sensory information to the brain

Parasympathetic

• Rest and digest

• Top and bottom of spinal cord

Sympathetic

• Fight or flight response

• Middle of spinal cord

Structures of the CNS

• Brain

  • Cerebrum, Telencephalon, Diencephalon

  • Brainstem

  • Cerebellum

Structures of CNS

• Spinal Cord

  • Cord

  • Conus Medullaris (cone shape lower end of spinal cord)

  • Cauda Equina (nerve roots at the end of the spinal cord)

Neurons

nerve cells, send signals via retro or anterograde transportation

Interneurons

nerve cells with short axons, send information locally

Nuclei

nerve cells with common function, grouped in a cluster, INSIDE the CNS

Glial Cells

Support (physical/chemical) activity of neurons, 10:1, many different types, a lot of glial cells in the brain

Ganglia

Nerve cells with a common function that are grouped OUTSIDE of the CNS

Synapse

chemical transmitters may cause excitation or inhibition

• Monosynaptic (reflex)

• Polysynaptic (complex behavior)

• Efferent - motor information from CNS to PNS

• Afferent - sensory information, from PNS to CNS

Tracts (fasciculi)

• Columns (funiculi)

  • Descend

  • Ascend

  • Decussate (cross over)

• Commissures

Cerebral Hemispheres

• Cerebrum

  • Right Hemisphere

  • Left Hemisphere

  • Sagittal sulcus separates left and right hemispheres

• Cerebral cortex

  • Gray matter, cell rich, cell bodies

• Nuclei

  • Cluster of cells, Basal ganglia

• White matter

  • Axons, connecting brain regions

Lobes of the Brain

• Frontal

• Parietal

• Temporal

• Occipital

• Insular ( Sensory motion)

• Limbic (Emotion, motivation, memory)

Frontal Lobe

Associated with

• Thoughts

• Planning

• Decisions

• Actions

• Cortical Motor system

• Central Sulcus- everything in front is considered the frontal lobe

Parietal lobe

Associated with

• Sensation (Feeling)

• Perception

Sensorimotor System

From central sulcus to parietal occipital sulcus

Occipital Lobe

• Dedicated to vision

• Dorsal Stream “where” parietal lobe

• Ventral Stream “what” temporal lobe

• Boundaries: temporal lobe laterally, parietal lobe medially

Temporal lobe

Associated with

• Auditory processing

• Language

• Memory

• Object identification (“ what pathway”)

- Separated from parietal lobe and frontal lobes by lateral sulcus . Imaginary line between temporal and occipital lobes.

Subcortical Structures- Thalamus

Sensory information

Basal Ganglia

hyper and hypo movement a lot or a little bit of movement

Hypothalamus

hunger, sleep, thirst

Hippocampal Formation

memory

Amygdala

emotions and fear

Corpus Callosum

Connects right and left hemisphere

Anterior Commissure

Helps connect connect hemispheres

Internal Capsule

Information about movement

Corona Radiata

cerebral hemisphere to brainstem

Brainstem

• Midbrain, Pons,Medulla

• Connections between the cerebral hemispheres, the spinal cord, and cerebellum

• Complex nuclei

  • Hearing, respiration, arousal, posture, locomotion

• Cranial Nerves

  • Most have nuclei in the brainstem and exit or enter the brainstem

Cerebellum

• “little brain”

• Posterior and inferior to the cerebellum

• Connects to the rest of the nervous system through the brainstem

• Cortex, deep cerebellar nuclei, white matter

• Motor function (Coordination)

• Motor learning (Movement adaptation)

Meninges/layers

• Multilayered membranes that enclose the nervous system and separate it from protective bony structures

  • Deep to superficial (Pia > Arachnoid> Dura)

Ventricles

CSF is within the ventricles

• 2 lateral ventricles (right and left)

• 3rd ventricle is midline around the midbrain

• 4th ventricle is midline and between the brainstem and the cerebellum

Lateral ventricles are connected by the interventricular foramen

3rd and 4th are connected by the cerebral aqueduct

Spinal Cord

• Vertebrae

  • Cervical (7)

  • Thoracic (12)

  • Lumbar (5)

  • Sacral (5)

  • Coccygeal (1)

• Fiber Tracts

  • Cord

  • Conus Medullaris

  • Cauda Equina

• Spinal Nerve Roots

Peripheral Nervous System

31 pairs of spinal nerves

• 8 Cervical

• 12 Thoracic

• 5 Lumbar

• 5 Sacral

• 1 Coccygeal

12 Cranial Nerves

Myotomes - group of muscles innervated by a nerve root

C5- Elbow Flexors L2- Hip Flexors

C6- Wrist Extensors L3- Knee Extensors

C7- Elbow Extensors L4- Ankle Dorsiflexors

C8- Finger Flexor L5- Long Toe Extensors

T1- Finger Abductors S1- Ankle Plantar Flexors

Dermatomes

Area of skin supplied by a nerve root

PNS

Motor and sensory axons coming out of and heading into the central nervous system