Chapter 13

14. Embryological Development

a. The Neural Tube

i. Endoderm develops into digestive and respiratory tract linings

ii. Mesoderm develops into muscle, bone, connective tissue, and cardiovascular structures

iii. Ectoderm develops into nervous system and epidermis

1. Neural plate

2. Neural groove

3. Neural fold
   Label the Diagram
   Neural fold

4. Neural tube

5. Neural crest

b. Primary and Secondary Vesicles

i. Prosencephalon develops into forebrain

1. Telencephalon develops into cerebrum

2. Diencephalon develops into thalamus and hypothalamus

ii. Mesencephalon develops into midbrain

iii. Rhombencephalon develops into hindbrain

1. Metencephalon develops into pons and cerebellum

2. Myelencephalon develops into medulla oblongata

c. Spinal Cord

Develops from the caudal portion of the neural tube

15. The Central Nervous System

A. Cerebrum

i. Cerebral cortex

ii. Longitudinal fissure

iii. Cerebral hemisphere

iv. Corpus callosum: What is its function?

→ Connects the right and left cerebral hemispheres

v. Basal nuclei: What is its function?

→ Regulates voluntary motor movements

vi. Basal forebrain: What is its function?

→ Memory, learning, and arousal

vii. Limbic system: What is its function?

→ Emotion, behavior, and memory

Viii. Gyrus and sulcus

→ Gyrus = ridge; Sulcus = groove

1. Lateral sulcus: Divides which lobe does it separate?
   → Separates the temporal lobe from the frontal and parietal lobes

2. Central sulcus: Divides which lobes?
   → Separates the frontal and parietal lobes

3. Parieto-occipital sulcus
   → Separates the parietal and occipital lobes

ix. Brodmann’s areas 41 and 42

→ Primary auditory cortex

x. Precentral gyrus

→ Primary motor cortex

xi. Broca’s area

→ Motor speech area

xii. Prefrontal lobe

→ Personality, judgment, and decision-making

xiii. Subcortical structures

1. Hippocampus
   → Memory formation

2. Amygdala
   → Emotional responses

3. Basal nuclei
   → Motor control

4. Substantia nigra: releases which neurotransmitter?
   → Dopamine

b. Diencephalon

i. Thalamus: What is its function?

→ Sensory relay station

ii. Hypothalamus: What is its function?

→ Maintains homeostasis; regulates temperature, hunger, thirst, and hormones

c. Brain Stem

I. Midbrain: What is its function?

→ Visual and auditory reflexes

ii. Pons: What is its function?

→ Regulates breathing and relays information

iii. Medulla: What is its function?

→ Controls vital autonomic functions

d. Cerebellum: What is its function?

→ Coordinates movement, balance, and posture

e. Spinal Cord

i. Anterior median fissure

ii. Posterior median sulcus

iii. Dorsal nerve root

→ Sensory input

iv. Ventral nerve root

→ Motor output

v. Gray horns

1. Posterior horn
   → Sensory neurons

2. Anterior horn
   → Motor neurons

3. Lateral horn
   → Autonomic (sympathetic) neurons

vi. White columns

1. Ascending tracts
   → Sensory

2. Descending tracts
   → Motor

3. Posterior columns
   → Sensory

4. Anterior columns
   → Motor

5. Lateral columns
   → Mixed

16. Circulation and the CNS

a. Arterial supply

i. Common carotid arteries

1. External carotid: supplies what area?
   → Face, scalp, and neck
   a. Orthostatic reflex

2. Internal carotid
   → Supplies the brain

3. Vertebral arteries

4. Basilar artery

5. Circle of Willis: What is its purpose?
   → Provides collateral circulation to the brain

b. Venous Return

i. Superior sagittal sinus

ii. Occipital sinuses

iii. Straight sinus

iv. Transverse sinuses

v. Sigmoid sinuses

vi. Jugular vein

c. Protective Coverings

i. Dura mater: Describe

→ Tough, fibrous outer layer

ii. Arachnoid mater: Describe

→ Web-like middle layer

1. Subarachnoid space: What is it filled with?
   → Cerebrospinal fluid (CSF)

2. Arachnoid granulations: What is its function?
   → Return CSF to venous circulation

iii. Pia mater: Describe

→ Thin, vascular inner layer

d. Ventricular System

i. Central canal

ii. Lateral ventricles

iii. Third ventricle

iv. Fourth ventricle

v. Cerebral aqueduct

vi. Choroid plexus

→ Produces CSF

vii. Cerebral Spinal Fluid (CSF)

→ Cushions and nourishes the CNS

17. The Peripheral Nervous System

a. Ganglia: Define

→ Clusters of neuron cell bodies outside the CNS

i. Dorsal root ganglion: Contains what types of cell bodies?

→ Sensory neuron cell bodies

ii. Sympathetic chain ganglia

→ Autonomic motor neuron cell bodies

iii. Plexus: Define

→ Network of intersecting nerves

b. Nerves

i. Structure

1. Epineurium
   → Surrounds entire nerve

2. Perineurium
   → Surrounds fascicles

3. Endoneurium
   → Surrounds individual axons

4. Fascicles
   → Bundles of axons

ii. Cranial nerves

1. CN I Olfactory:
   → Smell

2. CN II Optic nerve:
   → Vision

3. CN III Oculomotor:
   → Eye movement

4. CN IV Trochlear:
   → Eye movement

5. CN V Trigeminal:
   → Facial sensation and chewing

6. CN VI Abducens:
   → Eye movement

7. CN VII Facial:
   → Facial expression and taste

8. CN VIII Vestibulocochlear:
   → Hearing and balance

9. CN IX Glossopharyngeal:
   → Swallowing and taste

10. CN X Vagus:
    → Parasympathetic control of thoracic and abdominal organs

11. CN XI Accessory:
    → Head and shoulder movement

12. CN XII Hypoglossal:
    → Tongue movement

iii. Spinal nerves

1. Cervical plexus
   a. Phrenic nerve: What does it supply?
   → Diaphragm

2. Brachial plexus
   a. Axillary nerve – Shoulder muscles
   b. Radial nerve – Posterior arm and forearm
   c. Ulnar nerve – Medial forearm and hand
   d. Median nerve – Anterior forearm and hand

3. Lumbar plexus
   a. Femoral nerve – Anterior thigh
   b. Saphenous nerve – Medial leg

4. Sacral plexus
   a. Sciatic nerve
   i. Tibial nerve
   ii. Fibular nerve

Check Your Understanding

17. The ridges in the cerebrum are gyri and the grooves are sulci.

18. Lower motor neurons originate in the anterior horn of the spinal cord.

19. Brodmann’s area 41 keeps information about hearing.

20. Broca’s area is responsible for speech production.

21. The prefrontal lobe forms the basis of personality and decision-making.

22. Structures punctured during a lumbar puncture: dura mater and arachnoid mater.

23. Functions of CSF: protection, nutrient delivery, and waste removal.

24. What causes sciatica? Compression or irritation of the sciatic nerve.