Anatomy of Nervous System

from ppt only

Three Major Plane Sections p

Coronal, Sagittal, Horizontal/Transverse

coronal

A plane that shows brain structures as seen from the front

sagittal

A plane that shows brain structures as seen from the side

Horizontal/Transverse

A plane that shows brain structures as seen from above

Anatomical Directions

dorsal, ventral, anterior, posterior, superior, inferior, lateral, medial, proximal, distal, ipsilateral, contralateral

dorsal

Toward the back, away from the ventral (stomach) side

Ventral

toward the stomach, away from dorsal (back) side

Protecting and Supplying of the Nervous System

•Meninges •Cerebrospinal Fluid •Blood Supply

Anterior

Toward the front end

Posterior

Toward the rear end

Superior

Above another part

inferior

Below another part

Lateral

Toward the side, away from the midline

Medial

Toward the midline, away from the side.

Proximal

Located close (approx.) to the point of origin or attachment

Distal

Located more distant from the point of origin or attachment

Contralateral

On the opposite side of the body.

Ipsilateral

on the same side of the bod

meninges

Layers of membranes that cover the CNS and PNS

1st Layer: Dura Mater (meninges)

Latin: "Tough Mother" • Composed of leather-like tissue

2nd Layer: Arachnoid Membrane (meninges)

Looks like spider's web in cross section

3rd Layer: Pia Mater (meninges)

latin: "Pious Mother • Transparent membrane sticking closely to the outside of the brain

meningitis Infection

(due to virus or bacteria) in meninges

meningiomas.

Tumors in the meninx's tissues

Cerebrospinal Fluid (CSF)

Protective fluid around the brain and spinal cord

Cerebrospinal Fluid (CSF)

has similar composition as blood plasma

Cerebrospinal Fluid (CSF)

floats brain within the skull

subarachnoid space

between arachnoid membrane and pia mater

central canal

a small central channel that runs the length of spinal cord

cerebral ventricles

four large internal chambers of the brain. Ventricles are hollow spaces in the brain

CSF circulates through

subarachnoid space, central canal, cerebral ventricles

choroid plexus

where CSF is produced

networks of capillaries that protrude into the ventricles from the pia mater.

new CSF

made 3 times a day

old CSF

reabsorbed into blood supply at the top of the head

Cerebrospinal Fluid (CSF)

Cushions the brain.

Prevents the neuron from giving maladaptive response due to pressure (ex: tumor that leads to seizure

Blood supply

flows through carotid arteries (sides of neck) and vertebral arteries (back of the skull).

Hemorrhagic

bleeding

Ischemia

lack of oxygen

brain

receives nutrients through blood supply.

brain

cannot store energy and interruptions of blood supply could lead to damages.

central nervous system

Tissues encased in bone

Central Nervous System (CNS)

Brain and Spinal Cord

central nervous system

• Covered in 3 layers of membrane

central nervous system

Cells do not regenerate (Permanent damage)

central nervous system

With Cerebrospinal Fluid

peripheral nervous system

Tissues not encased in bone

Peripheral Nervous System (PNS)

Covered in 2 layers

Peripheral Nervous System (PNS)

All nerves exiting the brain and spinal cord - carrying sensory and motor messages to and from other parts of the body

Peripheral Nervous System (PNS)

Cells regenerate (With recovery)

Peripheral Nervous System (PNS)

Without Cerebrospinal Fluid

NERVE

a set of actions in the periphery, either from the CNS to a muscle or gland or from a sensory organ to the CNS.

nucleus (pl. nuclei)

a cluster of neuron cell bodies with shared functions within the CNS

ganglion

a cluster of neuron cell bodies, usually outside the CNS (as in the sympathetic nervous system)

Spinal Cord

within the vertebral column. It extends from medulla to the first lumbar vertebra.

spinal cord

communicates with all the sense organs and muscles except those in the head.

spinal cord

cord is shorter than the vertebral column.

The central canal

runs down in the center of the spinal cord.

White matter

composed of myelinated axons

grey matter

H-shaped, densely packed with cell bodies and dendrites.

dorsal roots

Axons from sensory neurons are found here

The cell bodies are grouped together outside the cord and forms the dorsal root ganglia.

ventral horns

Axons from motor neurons are found here. They are responsible for movement.

ventral horns

The cell bodies are found here

dorsal horns

Most of the synaptic terminals are here

• 8 cervical nerves

serve the area of the head, neck, and arms

• 12 thoracic nerves

serve most of the torso

5 lumbar nerves

serve the lower back and legs

31 segments of spinal cord

8 cervical nerves, 12 thoracic nerves, 5 lumbar nerves, 5 sacral nerves, 1 coccygeal nerve

5 sacral nerves

serve the backs of the legs and the genitals

Paraplegic

Lumbar-level damage that leads to loss of sensation and inability to move the lower torso and legs. Arms and upper torso are retained.

Quadriplegic

(quad meaning four – loss of four limbs) – Cervical damage that leads loss of sensation and inability to move the arms, legs, and torso.

sensation and voluntary movement

Damage to the spinal cord results in loss of _ (of both the skin and internal organs) and loss of _in parts of the body served by nerves located below the damaged area.

developing brain

has three swellings which will eventually develop into adult forebrain, midbrain, and hindbrain.

encephalon

Within the head”

5 divisions of the adult brain

Telencephalon, Diencephalon, Mesencephalon, Metencephalon, and Myelencephalon

Hindbrain

The posterior (likod) part of the brain, consists of the medulla, the pons, and the cerebellum.

Myelencephalon and Metencephalon

the two division of Hindbrain

Pons and Cerebellum

two major structures of Metencephalon

Myelencephalon or Medulla or Medulla Oblongata

The most posterior division of the brain

Reticular formation

a complex network of about 100 tiny nuclei that runs along the midline of brainstem from medulla up into the midbrain. Plays important role in regulation of sleep and arousal

Reticular formation and cranial nerves

important structure of myencephalon or medulla

cranial nerves

originating in the medulla control vital reflexes such as breathing, heart rate, vomiting, salivation, coughing, and sneezing .

pons

Means “bridge” in Latin.
• Anterior and ventral to the medulla

cochlear nucleus, vestibular nucleus, raphe nuclei, locus coeruleus

important structures of pons

Cochlear nucleus (pons)

receives information about sound

Vestibular nucleus (pons)

receives information about the position and movement of head. Helps in keeping our balance

Raphe nuclei (pons)

regulation of sleep and arousal

Locus Coeruleus (pons)

participates in arousal

Cerebellum

Means “little brain” in Latin.
• Large hindbrain structure with many deep folds
• An important sensorimotor structure coordinating and control of movements, maintaining muscle tone, and regulating balance.

• Damage in here affects skilled movements and speech production.

tectum and tegmentum

two division of midbrain (mesencephalon)

Tectum

Roof /dorsal/top half of the midbrain
• Tectum is the Latin word for “roof.”
- covers the tegmentum

Tegmentum

• intermediate level/ventral/bottom half of the midbrain.
  • Tegmentum is the Latin word for “covering”.

• the tegmentum covers several other midbrain structures.

Tectum

composed of two pairs of bumps or swellings called colliculi (little hills)

Inferior colliculi

Posterior pair
• Auditory function. Includes auditory reflex (turning of head on loud noise direction), and localization of sounds in an environment.

Superior colliculi

Anterior pair
• Visual-motor function, specifically visual guided movements -to direct the body’s orientation toward or away from particular visual stimuli. Also includes variety of visual reflex – changing of pupil size in response to light conditio

Periaqueductal Gray, Substantia Nigra, Red Nuclei

significant structures of tegmentum

Red Nuclei

• Located within the reticular formation
• Communicates motor information between spinal cord and the cerebellum

Substantia Nigra

Literally means “black stuff”
• Motor nuclei that is an important component of sensorimotor system
• Degeneration occurs in Parkinson’s disease

Periaqueductal Gray

• Gray matter situated around cerebral aqueduct.

• Has important role in perception of pain specifically mediating the analgesic (pain-reducing) effects of opioid drugs.