L14: Introduction to neuroanatomy

Question 1

What are the different divisions of the nervous system?

Answer 1

CNS: brain, brainstem, spinal cord, cerebellum
PNS: includes cranial nerves

Question 2

What is the forebrain?

Answer 2

Cerebrum and the diencephalon (deep structures)
(mostly cerebrum)
-sits on top of the brainstem

Question 3

What does the diencephalon consist of?

Answer 3

Hypothalamus, 2x thalamus

Thalamus: act as relay stations for all the senses coming from the body

Question 4

What are the 3 key parts of the brainstem?

Answer 4

Top to bottom:
Midbrain
Pons (bulges)
Medulla

Question 5

What is the cerebellum?

Answer 5

Structure found behind the brainstem, and has connections to the brain stem

Question 6

What is the cerebrum?

Answer 6

Split into 2 hemispheres
Cortex: grey matter, around outside, due to high density of cell bodies
White matter: myelinated axons

Grey matter can be found in the middle of the brain e.g. the thalami

Question 7

Why do we have gyri and sulci?

Answer 7

Increase the SA, and therefore the number of neurones we can pack inside the brain

Question 8

What are fissures?

Answer 8

Deeper than sulci
Longitudinal fissure splits the hemispheres
Lateral fissure

Question 9

What separates the hemispheres into lobes?

Answer 9

Certain gyri, sulci and fissures

Question 10

What are the 4 key lobes?

Answer 10

Frontal (L/R)- central sulcus denotes the most posterior portion of the frontal lobe
Parietal (L/R)- past central sulcus, parieto-occipital sulcus can be seen medially and separates the parietal lobe from the occipital lobe
Occipital (L/R)- past the parietal lobe, the sulcus to denote this is hard to see on the brain
Temporal (L/R)- laterally, denoted by lateral fissure against the frontal and parietal, but the distinguisment b/w temporal and occipital is hard to see

Question 11

What is the corpus callosum?

Answer 11

Collection of white matter (packed full of neuronal axons)

-allows communication between the two hemispheres

Question 12

What is attached to the hypothalamus?

Answer 12

Pituitary gland, which is attached via the pituitary stalk

Question 13

What is the septum pellucidum?

Answer 13

Thin membrane splitting the cavity below the corpus callosum which is filled with cerebrospinal fluid

Question 14

What does rostral and caudal mean (orientation terminology of brain)?

Answer 14

Rostral: towards nostril (same as anterior)
Caudal: towards tail (same as posterior)
The orientation terminology of the spinal cord is not equivalent to the terminology of the brain, as the brain is on an angle.

Question 15

What are the nerves associated with different regions of the brainstem?

Answer 15

Cranial nerves (you have pairs of cranial nerves, so you have each one of the pair emerging from either side of the brainstem)

Question 16

What is the major function of the brainstem?

Answer 16

Midbrain: coordinating eye movement and reflexes of pupils in response to light
Pons: feeding (trigeminal nerve-muscles of mastication), controlling sleep
Medulla: cardiovascular and respiratory systems

Question 17

Why is even just a small lesion in the brainstem significant?

Answer 17

There is a lot of nervous tissue packed into a small area

Question 18

What are the key functions of the frontal lobe?

Answer 18

• voluntary motor control (gyrus just in front of central sulcus: pre-central gyrus)
• speech production
• social behaviour
• impulse control
• higher cognition

Question 19

What is known as the primary motor complex?

Answer 19

Pre-central gyrus

Question 20

What are the key functions of the temporal lobe?

Answer 20

-language
-emotion
-long term memory
Special senses:
-sense of smell
-hearing
-taste

Question 21

What are the key functions of the parietal lobe?

Answer 21

• spatial awareness

- processing sensory info (not special senses): somatosensory perception: post-central gyrus

Question 22

What are the key functions of the occipital lobe?

Answer 22

Visual perception

Question 23

What is the function of the cerebellum?

Answer 23

Co-ordination and motor learning

-sits just beneath the tentorium cerebelli

Question 24

What is the uncus?

Answer 24

Most medial part of the temporal lobe, receives olfactory info
-uncus can be pushed past the tentorium through the tentorium notch when there is a rise in pressure in the skull= UNCAL HERNIATION

Question 25

What nerve is the uncus very close to?

Answer 25

3rd cranial nerve coming off the midbrain: oculomotor nerve

-uncal herniation can push against this nerve

Question 26

How is the primary motor cortex described as homunculus?

Answer 26

Homunculus means little man
If you cut coronally into the complex specific parts of the cortex are responsible for specific part of the bosy
Laterally to medially: pharynx, tongue, face, hands, arms, trunk, legs, feet, genitals
(head and neck will be found laterally)

-somatosensory complex is similar to this however some parts are more heavily represented (lips, tongue, fingertips)

Question 27

Why is the topography of the brain important?

Answer 27

You can localise what part of the body a lesion to the brain will affect

Question 28

How does the motor cortex link to the peripheral nervous system?

Answer 28

The primary motor cortex in one half of the brain is responsible for the motor control in the contralateral side of the body.
-motor neurone runs down same side as the side it arose, at the level of the medulla the neurone crosses to the opposite side, where it runs down that side of the spinal cord and synapse with a spinal nerve

(this is the same with the sensory cortex)

Question 29

Are all cranial nerves mixed like spinal nerves are?

Answer 29

No, only some cranial nerves are mixed, the rest are motor

Question 30

What is the relationship between the motor cortex and the cranial nerves?

Answer 30

-the motor nerve runs down the ipsilateral side, until it reaches a point where it wants to communicate with cranial nerves on that side
-it needs to cross as it is also contralteral, however it crosses adjacent to the cell body onto which it will synapse
However
-there is also some control from the ipsilateral cortex
Dual cortical innervation to cranial nerves

Question 31

What does it mean when you say that spinal nerves have uni-cortical control?

Answer 31

The spinal nerves receive input from just one primary motor cortex (uni-cortical, e.g. right and left)

Question 32

Which cortex has dominant control over the cranial nerve?

Answer 32

Contralateral cortex, ipsilateral control only comes into play when something happens to the dominant pathway

Question 33

What is the definition of decussate?

Answer 33

Cross over

Question 34

Do all cranial nerves have cortical input from the ipsilateral cortex?

Answer 34

No, not all do