Spinal Cord, Meninges, and Ventricles

Question 1

Peripheral Nervous System

Answer 1

The parts of the nervous system outside of the brain and spinal cord:

1. cranial nerves
2. spinal nerves
3. Autonomic Nervous System: sympathetic and parasympathetic

Question 2

Somatic Nervous System

Answer 2

Voluntary control; sensory and motor nerves innervate the muscles and skin

Question 3

Autonomic Nervous System

Answer 3

Involuntary control; sensory and motor nerves innervate visceral organs and glands

Provides neural control of smooth muscle, cardiac muscle, glandular secretory cells or a combination of these;

Cranial nerves, medulla (involuntary fxs), hypothalamus (autonomic function, hormone) receive info from ANS

Question 4

Sympathetic System

Answer 4

Part of the ANS: energy expenditure via involuntary arousal of glands/organs; flight or fight response

Question 5

Parasympathetic System

Answer 5

Part of the ANS: energy conservation via calming aroused glands/organs; restoration of homeostasis

Question 6

Spinal Cord Anatomy

Answer 6

Origin = Foramen Magnum

Termination = around Vetebra L1

Divided into five sections:

cervical (n = 8)

thoracic (n = 12)

lumbar (n= 5)

sacral ( n = 5)

coccygeal (n = 1)

31 sections of vertebrae and 31 pairs of spinal nerves (one each side)

Question 7

Spinal Cord Info

Answer 7

Thoracic and lumbar regions of SC thicker and bigger than higher or lower areas; all sections have same orientation points:

• Two ventral horns/two dorsal horns
• Ventral root/dorsal root

Gray/white matter reverse of brain; white ext, gray int

CSF flows through central canal; Spinal cord contained in vertebral canal

S input collected somewhere in the body and transferred to the brain /S up, M down/

impulse travels to spinal cord through dorsal horn; goes straight up thru SC, through thalamus, to processing cortex; Motor impulse sent back down through basal ganglia, SC, thru ventral horn, to muscles

Question 8

Spinal Nerves

Answer 8

are sensory, motor and mixed orientation

each spinal nerve per hemisphere is connected by 2 roots: Dorsal root collects S inputs/ Ventral root sends M impulses

Roots are sometimes included in the entirity of the nerve, but somewhat separate; two roots per spinal nerve side; one V, one D

spinal nerves enter and exit the vertebrae via Intervertebral foramen; Discs keep pressure off nerves

Question 9

Upper Motor Neurons

Answer 9

Cell bodies in the motor cortex and their descending axonal processes that synapse on the cranial and spinal motor neurons

Question 10

Lower Motor Neurons

Answer 10

Motor neurons of cranial nerves and spinal cord which send their axonal processes to the skeletal muscle loss of these neurons leads to weakness, twitching (fasciculation) and atrophy of muscles

Question 11

UMN vs LMN Injury

Answer 11

Damage to horns, roots of nerves – LMN; Damage within tract of SP – UMN

LMN damage is always a ventral issue; Descending tracts are always motor tracts

Once impulse leaves spinal tracts and reaches the ventral horn of the appropriate spinal nerve, it chxs from UMN to LMN

Examples: damage to the dorsal horn of the vestibulospinal tract will signify a LMN damage – False, bc dorsal is S only

Lesion in midbrain – UMN; maxillary branch of the trigeminal nerve – LMN

Question 12

Relex Arc

Answer 12

Motor response initiated at spinal level; reflexive response – pain, hot –

Once impulse reaches dorsal horn will jump to interneuron – interneuron will xfer impulse to ventral horn and back out thru the nerve to muscles for movement without transferring impulse up spinal cord to brain

An ex of cooperation btwn CNS and PNS to conserve energy

Damage on SC, cant send appropriate S message; cant initiate response (Hand laying on hot stove – no S input, no input of pain, no M response)

Question 13

Plexus

Answer 13

Collection of spinal nerves that serve a specific fx cervical plexus:

nerves C1 to C5* - diaphragm, muscles of shoulder and neck

brachial plexus: C5 to T1 – triceps, arms, wrists

lumbar plexus: T12 to L4 – lwr abdomen, buttocks, antr thigh

saccral plexus: L4 to S4 -

Question 14

meninges

Answer 14

The three protective membranes that cover the central nervous system; cerebrum, cerebellum and spinal cord

1. Dura mater - thickest, provides most protection; two layers
2. Arachnoid mater
3. Pia mater - closest to the tissues, softest layer

Question 15

Dura Mater

Answer 15

Cerebral: Adheres to the inner skull; composed of two fused (periosteal-outer and meningeal-inner) layers that split to form sinuses that carry blood from veins and absorb CSF

Two potential spaces only present in pathologies; both sites of vascular hemorrhage

1. epidural (betwn dura and bone)
2. subdural (betwn dura and archnoid)

Spinal: Composed only of meningeal layer; seperates from vertebrae by epidural space

Question 16

Dural Extensions

Answer 16

supportive tents of connective tissues that helps to keep the cerebrum and cerebellum supported and stable, especially during severe head movements (concussions, car accidents, etc); can tear easily

Falx cerebri - largest ext; sickle-shaped; separates the cerebrum hemis

Tentorium cerebelli - covers cerebellum; attaches to temporal bone and falx cerebri

Falx cerebelli - smalles ext; triangular; separates the cerebullum hemis

Question 17

Arachnoid Mater

Answer 17

Cerebral: thin, non-vascular membrane that surrounds the sulci and folds of the brain bridges the area between dura mater and pia mater; has distinctive structures:

1. Arachnoid mater; separated from dura by subdural space
2. Arachnoid traebeculae; “stalks” that fill space btwn pia and arachnoid (subarachnoid space)
3. Subarachnoid space; filled with CSF; Arachnoid granulations drain old CSF into vascular system

Spinal: subarachnoid space filled with CSF as it surrounds the spinal cord

Question 18

Pia Mater

Answer 18

Cerebral: “Gentle mother”; thin transparent, collagenous membrane; closely attached to the surface of the brain, surrounds the perivascular space

interwoven with a network of arteries/veins; helps maintain and support blood vessels so that brain receives appropriate nutrients (crucial role)

the arachonoid and pia together termed leptomeninges

Spinal: tightly surrounds the spinal cord; the dorsal/ventral roots of spinal nerves will pierce the pia mater to make contact with spinal cord