Anatomy-External Topography

Question 1

How does the brain divide as it becomes fully developed?

Answer 1

It starts as an embryonic structure with a forebrain, midbrain (1:mesencephalon) and hindbrain. The forebrain differentiates into the 2) telencephalon and 3) diencephalon. The hindbrain develops into the 4) metencephalon and 5) myelencephalon.

Question 2

What are the main components of the telencephalon? Diencephalon? Mesencephalon? Metencephalon? Myelencephalon?

Answer 2

Telencephalon: cerebral hemispheres. Diencephalon: Hypothalamus & thalamus. Mesencephalon: midbrain. Metencephalon: Pons & Cerebellum. Myelencephalon: Medulla.

Question 3

What are the four functional divisions of the nervous system?

Answer 3

Motor, sensory, autonomic and limbic systems.

Question 4

How does the anatomical description of the CNS change above the midbrain compared to the midbrain and below?

Answer 4

Above the midbrain: superior=dorsal, inferior=ventral, anterior=rostral and posterior=caudal. Midbrain & below: superior=rostral, inferior=caudal, anterior=ventral and posterior=dorsal.

Question 5

What portions of the CNS contain cell bodies?

Answer 5

Gray matter

Question 6

What portions of the CNS contain myelinate axons?

Answer 6

White matter

Question 7

Why has popular cultured deemed the left side of the brain the dominant side?

Answer 7

It is responsible for speech.

Question 8

What structures are indicated in the image below?

Answer 8

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Question 9

How do you estimate the lateral limit of the parietal lobe?

Answer 9

An imaginary line from the parieto-occipial sulcus to the preoccipital notch.

Question 10

How do you go about finding the deeper area of cerebral cortex called the insula?

Answer 10

Lift the lateral fissure and look deep to the frontal, parietal and temporal lobes that are adjacent to this fissure.

Question 11

Name the different sulci and gyri seen in the image below.

Answer 11

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Question 12

In what order does the homunculus go ventral to dorsal in the pre and post-central gyri?

Answer 12

Face, hand and arm are found on the lateral side of the hemisphere. The lower limbs and external genitilia are found on the medial side of the hemisphere.

Question 13

Identify the different structures indicated in the image below.

Answer 13

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Question 14

Identify the different structures indicated in the image below.

Answer 14

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Question 15

Identify the different structures indicated below.

Answer 15

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Question 16

A patient comes to see you in clinic with his wife. He is quite old and you first notice that he is having extreme difficulty explaining himself. He can only describe things one word at a time. If MRI reveals a brain lesion, where would this lesion likely be?

Answer 16

Broca’s area (the pars opercularis + pars triangular is in the inferior frontal gyrus in the dominant hemisphere). This area controls the motor aspects of speech production, allowing patients to speak fluently.

Question 17

A 79 year old male comes to see you a few weeks after having a stroke. He complains that he keeps bumping into things and has bruises on his face. You notice that the left side of his face is unshaven and the right side of his face is clean shaven. When asked to draw a clock he only draws the right side of the clock. Where did his stroke most likely affect his brain?

Answer 17

The non-dominant (usually right) inferior parietal lobule. A lesion of this sort produces contralateral hemineglect where the patient ignores the contralateral half of the external world and his body.

Question 18

A 79 year old male comes to see you a few weeks after having a stroke. He complains of inability to write, do math and understand what others are saying to him. Where did the stroke most likely cause a lesion in his brain?

Answer 18

Lesions of the dominant (usually left) side of the parietal lobule. A lesion of this sort causes impairment of higher functions like doing math, comprehending speech and writing.

Question 19

In what region of the brain is information derived from both ears processed?

Answer 19

Transverse gyri of Heschl. They are one or two short gyri that lie on the superior surface of the superior temporal gyrus.

Question 20

A patient comes to see you in clinic after he recovers from a serious car accident. His wife complains that he speaks gibberish, but can respond perfectly to her questions if he writes down his response. Where is the most likely location of a lesion in this patient’s brain?

Answer 20

Wernicke’s area. Patients will not respond appropriately to questions and have nonsensical speech.

Question 21

What is the corpus callosum made out of?

Answer 21

White matter

Question 22

What are the different parts of the corpus callosum?

Answer 22

Rostrum, genu, body and splenium

Question 23

A 23 year old marine comes to see you after a blast injury. Everything has healed fine, except he cannot feel or move his right lower extremity. If his spinal cord was completely in tact, where might the lesion be found on his brain?

Answer 23

The left paracentral lobule. This is the area of the brain responsible for lower extremity motor AND somatosensory function on the medial portion of the contralateral hemisphere.

Question 24

What structures are responsible for defining the parietal lobe?

Answer 24

Parieto-occipital sulcus (on medial side of hemisphere) and the central sulcus (on the lateral side of hemisphere)

Question 25

A patient comes to see you after falling from a ladder while washing windows. He doesn’t remember much because he blacked out after the fall, but now he cannot see the right half of his visual field with his left eye nor the left half of his visual field with his right eye. Where might this patient have a lesion on his brain that would cause these symptoms?

Answer 25

Within the cuneus. This is where the primary visual cortex is located. Lesions to this area may cause contralateral homonymous hemianopsia.

Question 26

What portion of the brain contains the inferior portion of the primary visual cortex and what structure does this merge with?

Answer 26

Lingual gyrus. It merges with the parahippocampal gyrus.

Question 27

What structure is indicated below?

Answer 27

The insula. It is buried by the frontal, parietal and temporal opercula.

Question 28

What structures are indicated in the image below? What are the names of the cranial nerves?

Answer 28

I: Olfactory. II: Optic. III: Oculomotor. IV: Trochlear. V: Trigeminal. VI: Abducens. VII: Facial. VIII: Vestibulocochlear. IX: Glossopharyngeal. X: Vagus. XI: Spinal accessory. XII: Hypoglossal.