Brainstem

Question 1

What are the three broad functions of the brainstem?

Answer 1

1. Conduit
2. Cranial nerve
3. Integrative

Question 2

How is the brainstem a conduit?

Answer 2

Information goes to the cortex and spinal cord thru the brainstem (white matter tracts)

Question 3

What are the integrative functions of the brainstem?

Answer 3

Complex motor patterns, cardiorespiratory control, reflexes

Mostly through reticular formation

Question 4

What are the three main anatomical subdivisions of the brainstem?

Answer 4

1. Medulla
2. Pons
3. Midbrain

Question 5

In the brainstem, where is the corticospinal tract?

Answer 5

Anterior portion

Question 6

In the brainstem, where is the spinothalamic tract?

Answer 6

Anterolateral

Question 7

In the brainstem, where is the medial leminscus?

Answer 7

Varies in location

Question 8

Where is the tegmentum located in each section of the brainstem?

Answer 8

Medulla: Posterior
Pons: Posterior
Midbrain: Middle

Question 9

Where is the tectum located in each part of the brainstem?

Answer 9

It is posterior to the ventricle in the pons and midbrain

Question 10

What consists of the stuff added to the tectum and tegmentum in each section?

Answer 10

Medulla: Olive and pyramid

Pons: Pons

Midbrain: cerebral peduncles

Question 11

What are some major external features in the medulla?

Answer 11

Anterior: Pyramids, pyramidal decusation, olive (anterolateral)

Posterior: Obex, cuneate and gracile tubercles

CN: IX, X, XII

Question 12

What are some external features of the pons?

Answer 12

Anterior: Basal pons

Posterior: Middle, inferior, and superior cerebellar peduncle

CN: VII, VIII

Question 13

What are some external features of the midbrain?

Answer 13

Anterior: Cerebral peduncles

Posterior: Cerebral aqueduct, superior colliculus, inferior colliculus, inferior brachium

CN: III, IV

Question 14

What are some distinct features of the caudal medulla?

Answer 14

• Clear central canal of grey matter
• Pyramidal decussation at anterior
• NO 4th ventricle

Question 15

What are distinctive features of the rostral medulla?

Answer 15

• Visible 4th ventricle in the posterior
• Olive with inferior olivary nuclei
• Hypoglossal nucleus
• space between two pyramids

Question 16

What are some distinctive features of the caudal pons?

Answer 16

• Large 4th ventricle in the posterior
• attached to cerebellum by middle cerebellar peduncle
• inferior cerebellar peduncle is visible

Question 17

What indicates middle pons vs. caudal pons?

Answer 17

Middle pons has larger superior cerebellar peduncle and no inferior cerebellar peduncle

Question 18

What are some distinct features of the rostral pons?

Answer 18

Looks like alien brain

• 4th ventricle is much smaller than caudal
• Lots of white matter in the pons including corticospinal tract

Question 19

What are some distinctive features of the caudal midbrain?

Answer 19

• Heavily stained decusation of the superior cerebellar peduncle right in the middle just anterior to the aqueduct
• Inferior colliculus on posterolateral aspects
• CN IV seperated from the rest of the structure laterally

Question 20

What are some distinctive features of the rostral midbrain?

Answer 20

• cerebral peduncles very lateral with large anterior space between them
• CN III in the middle of the structure
• substantia Nigra between the cerebral peduncles and the superior cerebellar peduncles

Question 21

What are the four types of axons in spinal nerves?

Answer 21

Somatic sensory: pain, temp., mechanorecepters

Visceral sensory: GI tract, blood vessels

Visceral motor: preganglionic autonomic

Somatic motor: innervate skeletal muscle

Question 22

How are the types of cranial nerve nuclei arranged in the brainstem?

Answer 22

Posterolateral to anteromedial

SS, VS, VM, SM

Question 23

What is different about the nuclear arrangement in the brainstem than in the spinal cord?

Answer 23

Not all columns are in all levels, and some are discontinuous

Question 24

Along with somatic sensory, visceral sensory, visceral motor, and somatic motor, what are the two other possible functions of cranial nerves?

Answer 24

Special sensory: hearing, equilibrium

Brachial motor: innervate muscles derived from pharyngeal arches (larynx, pharynx, jaw, face)

*No cranial nerve has all 6

Question 25

What is the name, type, and function of cranial nerve I?

Answer 25

Olfactory Special Sensory afferent Smell

Question 26

CN II?

Answer 26

Optic Special sensory afferent Vision

Question 27

CN III?

Answer 27

Oculomotor General sensory efferent, general visceral efferent Eye movement, pupil constriction and accommodation (focus)

Question 28

CN IV?

Answer 28

Trochlear General sensory efferent Eye movement

Question 29

CN V?

Answer 29

Trigeminal General sensory afferent, Special visceral efferent Head and neck sensation, motor for muscles of mastication

Question 30

CN VI?

Answer 30

Abducens General sensory efferent Eye movement

Question 31

CN VII?

Answer 31

Facial General sensory afferent, Special sensory afferent, Special visceral efferent, General visceral efferent Sense around ear, taste, facial expression, secretomotor

Question 32

CN VIII?

Answer 32

Vestibulocochlear Special sensory afferent Hearing and balance

Question 33

CN IX?

Answer 33

Glossopharyngeal Special Visceral efferent, General visceral efferent, General visceral afferent, General sensory afferent, Special sensory afferent Stylopharyngeus, secretomotor, carotid body and sinus, part of tongue, taste

Question 34

CN X?

Answer 34

Vagus Special visceral efferent, General visceral efferent, Special sensory afferent, General sensory afferent Pharynx/larynx muscles and glands, stretch and chemoreceptors in aorta, skin on back of ear

Question 35

CN XI?

Answer 35

Accessory Special visceral efferent Sternomastoid and trapezius

Question 36

CN XII?

Answer 36

Hypoglossal General sensory efferent Tongue

Question 37

From where does the blood supply come from for the brainstem?

Answer 37

Two caudal vertebral arteries come together to form basilar artery These vertebral arteries, the basilar artery and its perforating branches supply the brainstem

Question 38

What arteries supply the lateral brainstem?

Answer 38

Circumferential arteries