Lecture 6 - Neuroanatomy

Question 1

What are the major components of the CNS? (brain and SC)

Answer 1

• Forebrain is comprised of cerebrum and diencephalon
• Cerebrum forms large portion of forebrain, sits above brainstem and is split into L+R hemispheres
• Diencephalon consists of hypothalamus & 2 x thalami
• Brainstem consisting of midbrain, pons & medulla

Question 2

Define:

Grey matter
White matter
Sulci
Gyri
Fissures

Answer 2

1) White matter = found on outer cortex of brain, high density of nerve cell bodies
2) Grey matter = deep to grey matter, high density of nerve fibres (axons)
3) Sulci = dips found on surface of brain
4) Gyri = ridges found on surface of brain
5) Fissures = longitudinal & lateral

Question 3

Which sulci separate the brain into lobes?

Which structure connects the 2 hemispheres of the brain together?

Answer 3

• Central sulcus separates the frontal and parietal lobe
• Lateral sulcus + temporal fissure separates temporal lobe
• Parieto-occipital sulcus separates occipital from parietal lobes
• The corpus callosum

Question 4

What is the terminology used for anatomical orientation of the brain?

Answer 4

1) Rostral (nostril) same as anterior
2) Caudal same as posterior
3) Superior same as dorsal
4) Inferior same as ventral

Unless brain is tilted upwards to face sky, at which point rostral becomes superior, caudal becomes inferior, dorsal becomes posterior and ventral becomes anterior.

Question 5

What are the 3 main sections of the brainstem?

What are the major functions of the brainstem?

Answer 5

• Midbrain, Pons & Medulla

1) Relationship w/CN’s, nuclei housed here responsible for control of eye movement and pupil response top light.
2) Pons plays role in feeding & controlling sleep
3) Medulla regulates CV and respiratory systems

• Therefore lesions to brainstem will affect number of neurological functions and everything is packed in tightly and includes CN’s

Question 6

What are the main 5 lobes of the brain and their primary functions?

Answer 6

1) Frontal - voluntary motor control, speech production, higher cognition & social behaviour
2) Parietal - somatosensory perception & spatial awareness
3) Temporal - language, emotion, smell, hearing, taste & long-term memory
4) Occipital - visual perception
5) Cerebellum - co-ordination & motor-learning

Question 7

Where is the primary motor cortex and primary somatosensory cortex found?

Answer 7

Primary motor cortex (involved in voluntary motor control) = on the pre-central gyrus, just rostral to central sulcus

Primary somatosensory cortex (involved in sensory perception) = on post-central gyrus, just caudal to central sulcus

Question 8

What does the motor and sensory homunculus represent?

Answer 8

They are neurological maps that give a topographical representation of the body dedicated to motor and sensory processing within the pre and post central gyrus respectively.

Means we can look at symptoms of brain lesions and locate where on the brain they have occured.

Question 9

Describe the course of pathways connecting the primary motor cortex to spinal nerves which control limbs (on one side)

Answer 9

Nerves descend downwards and decussate to opposite side at the level of the medulla. Therefore cortical control of limb movement from PMC is contralateral.

Question 10

Describe the relationship between the motor cortex and cranial nerves innervating the head and neck?

Answer 10

Pathways from PMC to CN’s decussate to opposite side at level of nuclei at which they communicate with, which means cortical control of muscles is contralateral.

HOWEVER

CN’s actually have a dual cortical innervation, as they also receive input from ipsilateral side. This is just a ‘back-up’ as they only come into play when dominant contralateral side is affected, e.g.: by a stroke