Neuroanatomy introduction

Question 1

Role of the Nervous System

Answer 1

• Detect changes in external and internal environment
• —-Receive sensory input
• Relay information and analyse it
• Initiate appropriate responses

Question 2

What are neurons and what is their function?

Answer 2

• Most basic functional unit of nervous system
• Convey information via electrical signals
• Receive, Integrate, Transmit
• Afferent/ Sensory neurons
• —-Carry information from receptors to the CNS
• Efferent/Motor neurons
• —-Carry information from CNS to peripheral effectors
• Interneurons
• —-Link afferents to efferents within CNS

Question 3

Subdivisions of the Nervous System

Answer 3

Central (brain and spinal cord) + Peripheral

Peripheral = Somatic (controls external actions) Autonomic (controls internal activities)

Autonomic = Sympathetic (arousing) and Parasympathetic (calming)

Question 4

Sub-divisions of the CNS

Answer 4

• Cerebrum (forebrain)
• • Consists of two parts:
• —- Outer brain (telencephalon)/Cerebral hemisphere
• —- Inner brain (diencephalon)
• Brainstem (Midbrain, pons, medulla oblongata)
• Cerebellum
• Spinal cord

Question 5

Neural tube

Answer 5

This tube develops three swellings (A, B, C) and begins to form a bend at the rostral end

Caudal end of tube develops to spinal cord

Rostral end of tube develops into brain

A: Forebrain - Prosencephalon
B: Midbrain - Mesencephalon
C: Hindbrain - Rhombencephalon

Question 6

2nd stage of the CNS development

Answer 6

Three swellings become five: Ai, Aii, B, Ci and Cii

Ai, Telencephalon; Aii, Diencephalon
B, Mesencephalon
Ci, Metencephalon; Cii, Myelencephalon

Question 7

Development of mature brain from neural tube
Prosencephalon (A)
= front brain

Answer 7

1. — 2 structures =
   Telencephalon (Ai)
   = far away brain which becomes the cerebral hemispheres.
   and
   Diencephalon (Aii)
   = across brain which becomes the diencephalon (thalamus and hypothalamus)

Question 8

Development of mature brain from neural tube
Primary vesicle = Mesencephalon (B)
= middle brain

Answer 8

2. Mesencephalon (B)
   = middle brain
   — Mesencephalon in the secondary brain vesicles and the Midbrain in the Mature brain.

Question 9

Development of mature brain from neural tube
Primary Vesicle: Rhombencephalon (C)
= rhomboid brain

Answer 9

3. Secondary brain vesicles = 2 x structures
   —–a. Metencephalon (Ci)
   = behind brain which becomes the pons and cerebellum
   and
   —–b. Myelencephalon (Cii)
   = marrow/cord brain which becomes the medulla oblongata.

Question 10

Features of an adult brain

Answer 10

Series of gyri and sulci

White matter

• • Axons
• • Tracts

Grey matter

• • Cell bodies
• • Nuclei
• • Point of synapse

Question 11

Lobes of the Brain

Answer 11

• Frontal Lobe
• Parietal Lobe
• Temporal Lobe
• Occipital Lobe

Question 12

What separates the 2 hemispheres of the brain?

Answer 12

Great Longitudinal fissure

Question 13

What links the 2 hemispheres together?

Answer 13

Corpus Callosum

Question 14

Sulci and Gyri function

Answer 14

Surface of cerebral hemispheres (i.e cerebral cortex) are heavily folded to increase surface area

Question 15

Grey Matter and location

Answer 15

Neuronal cell bodies and located mostly on the outside part of the brain. Some e.g. basal ganglia located in the centre.

Question 16

White matter

Answer 16

Nerve Axons

Question 17

Spinal cord and Spinal nerves

Answer 17

33 Vertebrae (bones)

31 spinal cord segments
8 Cervical (C1-C8)
12 Thoracic (T1-T12)
5 Lumbar (L1-L5)
5 Sacral (S1-S5)
1 Coccygeal (Co1)

Each segment gives rise to
1 pair segmental spinal nerves
= 31 Pairs of spinal nerves (PNS)

Question 18

Reason for the Cauda Equina

Answer 18

Growth of nerves stops way before the growth of bones. Nerves closer to the end of the column travel down the column before they can exit out near their respective vertebra.

Question 19

Arrangement of the spinal nerve coming out of the column: Dorsal and Ventral?

Answer 19

Made of ventral and dorsal rootlets initially
Ventral rootlets > form a ventral root

Dorsal Rootlets > combine to form dorsal root first > then dorsal root ganglion (sensory neurones have the cell body ~halfway down the axon = the ganglion is where the cell bodies amass to create the swelling)

Dorsal + Ventral Roots > combine to form spinal nerve = motor and sensory neurones.

Question 20

Peripheral Nervous System- 2 types of fibers and functions?

Answer 20

Sensory (Afferent) Fibers
Sends info TO the CNS

Motor (Efferent) Fibers
Sends info AWAY FROM the CNS