Test 5- Spine/ Brain Nerves

Question 1

Explain the Spinal Cord structure:

Answer 1

• it extends from Foramen magnum to second lumbar
• gives rise to 31 pairs of spinal nerves
• not uniform in diameter throughout length
  Cervical enlargement : supplies upper limbs
  Lumbar enlargement: supplies lower limbs

Question 2

Name the 4 segments of the spinal cords:

Answer 2

• cervical
• thoracic
• lumbar
• sacral

Question 3

What is Meninges?

Answer 3

Connective tissue that surrounds the spinal cord and brain

Question 4

List the meninges of the spinal cord ?

Answer 4

• Dura mater: continuous with epineurium of the spinal nerves
• Arachnoid mater: thin and whispy
• Pia mater: bound tightly to surface of brain and spinal cord.

And the spaces are :
- Epidural: anesthesia injected. Contains blood vessels, CT and fat

Subdural: serous fluid
Subarachnoid: CSF and blood vessels

Question 5

Explain basic function of reflexes

Answer 5

• automatic response to a stimulus that occurs without conscious thought.
• homeostatic

Question 6

Explain the components of reflexes

Answer 6

- action potentials produced in:
Sensory receptors 
Sensory neuron
Inter neuron 
Motor neuron 
Effector organ

Question 7

Explain the reflex Arc

Answer 7

-1. A sensory receptor detects a stimulus

2. A sensory neuron conducts action potentials through the nerve and dorsal root to the spine
3. In spinal cord, sensory neuron synapses with an interneuron
4. The interneuron synapses with a motor neuron
5. A motor neuron Axon conducts action potential through the central root and spinal nerve to effector organ

Question 8

List the variety of reflexes

Answer 8

• some integrated within spinal cord; some within brain
• some involve excitatory neurons yielding a response
• some involve inhibitory neurons that prevent an action
• higher brain centres can influence, suppress, or exaggerate reflex responses

Question 9

Explain muscle stretch reflex :

Answer 9

• Muscles contract in response to a stretching force applied to them.
• they have muscle spindles: which are a specialized muscle cell that responds to stretch

Question 10

Reciprocal innervation:

Answer 10

Causes relaxation of extensor muscles when flexor muscle contracts

Question 11

Crossed extensor reflex

Answer 11

When a withdrawal reflex is initiated in one lower limb, the crossed extensor reflex causes extension of opposite lower limb

Question 12

What does the spinal nerve consist of ?

Answer 12

• axon bundles
• Schwann cells
• connective tissue
• Endoneurium: surrounds individual neurons
• Perineurium: surround axon groups to form fascicles
• Epineurium : surrounds the entire nerve

Question 13

Explain the organization of the spinal neves

Answer 13

• 31 pairs of spinal nerves
• first pair exit vertebral column between skull and atlas
• last four pair exit via the sacral foramina
• others exit through intervertebral foramina
• 8 pair cervical , 12 pair thoracic, 5 pair lumbar, 5 pair sacral, 1 pair coccygeal

Question 14

Cervical Plexus

Answer 14

• C1-C4

- innervation superficial neck structures, skin of neck, posterior portion of head

Question 15

Phrenic nerve

Answer 15

• C3-C5

- innervate diaphragm

Question 16

Brachial plexus

Answer 16

• C4 from cervical plexus plus C5-T1
• five central rami form there trunks Yahtzee separate into six divisions then form cords that give rise to:

Branches/ Nerves

• axillary
• radial
• musculocutaneous
• ulnar
• median

Question 17

Median nerve

Answer 17

C5-T1

Movement of forearm and hand

Question 18

Lumbar and sacral plexuses

Answer 18

Lumbar plexus: central rami if L1-L4

Sacral plexus: central rami of L4-S4

-Usually considered together because of their close relationship

• four major nerves exit and enter lower limb
  
  • obturator
  • femoral
  • tibial
  • common fibular

Question 19

Obturator nerve

Answer 19

Rotates thought laterally

L2-L4

Question 20

Femoral nerve

Answer 20

Flexes hip
Flexes/ extends knee
L2-L4

Question 21

Tibial and common fibular nerves

Answer 21

The two nerves together referred to as the Sciatic nerve

Question 22

Tibial nerve

Answer 22

Extends hip/ flexes knee

L4-S3

Question 23

Common fibular nerve

Answer 23

L4-S2

Extends hip and flexes knee

Question 24

Coccygeal plexus

Answer 24

S5
Muscles of pelvic floor
Sensory info from skin over coccyx

Question 25

What does the Diencephalon contain ?

Answer 25

Thalamus- influences mood/ movement subthalamus- contains nerve Tracts and nuclei epithalamus- contains pineal gland hypothalamus - major control centre for maintaining homeostasis

Question 26

Brainstem

Answer 26

- Connects spinal cord to cerebrum | - consists of medulla oblongata, pons, and midbrain

Question 27

Medulla oblongata

Answer 27

- Most inferior part - continuous with the spinal cord; has both ascending and descending nerve tracts - important for several reflexes such as heart rate, breathing, swallowing, vomiting ) - two prominent enlargements on the anterior surface of the MO are called pyramids, they control conscious control of skeletal muscles. The olives are two rounded oval structures, they are important for balance , coordination and modulation of sound from the inner ear.

Question 28

Pons

Answer 28

Contains ascending and descending nerve Tracts, relays info between cerebrum and cerebellum, site of reflex centres - pontine relay between cerebrum and cerebellum - also initiates REM stage while sleeping

Question 29

Midbrain

Answer 29

Contains ascending and descending nerve tracts, serves as visual reflex centre; part of auditory pathway Nuclei - of cranial nerves III-V

Question 30

Reticular formation

Answer 30

Scattered throughout Brainstem Contrail cyclic activities Such as the sleep-wake cycle

Question 31

Cerebellum

Answer 31

Controls muscle movement Governs balance Involved in learning motor skills Attached to Brainstem posterior to pons

Question 32

Cerebrum

Answer 32

- largest potion of bran - composed of right and left hemispheres which has the following lobes: frontal, parietal, occipital, temporal, insula Controls perception, thought and conscious motor activity, can override most other systems

Question 33

Purkinje cells in cerebellar cortex

Answer 33

- largest in CNS - receive 200,000 synapses, are inhabitory, only cerebellar cortex neurons that send axons to cerebellar nuclei - cortex has 1012 neurons; more than cerebral cortex

Question 34

Cerebellar functions

Answer 34

Flocculonodular lobe: balance and eye movements Vermis: posture, locomotion, fine motor coordination leading to smooth movements Lateral hemispheres: works with cerebrum to plan, practice , learn complex movements

Question 35

Diencephalon

Answer 35

Located between Brainstem and cerebrum

Question 36

Thalamus

Answer 36

Two lateral portions connected by the intermediate mass Surrounded by third ventricle Sensory info from spinal cord synapses here before projecting to cerebrum

Question 37

Subthalamus

Answer 37

Involved in controlling motor function Several ascending and descending nerve tracts

Question 38

Epithalamus

Answer 38

Habenula: emotional and visceral response to odours Pineal gland: may influence sleepiness, helps regulate biological clock, man play a role in onset of puberty

Question 39

Hypothalamus:

Answer 39

- most inferior portion of Diencephalon | - important in regulation of mood, emporium, sexual pleasure, rage and fear.

Question 40

Cerebrum hemispheres

Answer 40

Frontal lobe: voluntary motor fiction, motivation, aggression, sense of smell, mood, personality and decision making Parietal lobe: reception and evaluation of sensory info except smell, hearing and Vision Occipital lobe: reception and integration of visual input Temporal lobe: reception and evaluation for smell and hearing, memory, judgment

Question 41

Limbic system

Answer 41

- emotions