Brainstem Morphology

Question 1

What is the level of a lesion in olfactory nerve (I)?

Answer 1

Telencephalon

Question 2

What is the level of the lesion for optic nerve (II)?

Answer 2

Diencephalon

Question 3

What is the level of the lesion for oculomotor (III) and trochlear (IV) nerves?

Answer 3

Midbrain

Question 4

What is the level of the lesion for trigeminal nerve (V)?

Answer 4

Pons

Question 5

What is the level of the lesion for abducens (VI), facial (VII), and vestibulochochlear (VIII) nerves?

Answer 5

Pontomedullary sulcus

Question 6

What is the level of the lesion for glossopharyngeal (IX), vagus (X), hypoglossal (XII), and spinal accessory (XI) nerves?

Answer 6

Medulla

Question 7

Describe the 8 major ascending and descending pathways in the brainstem

Answer 7

Spinal lemniscus: conveys pain and temp info from opposite 1/2 of body
Medial lemniscus: conveys propriorceptive, vibratory, and 2-pt tactile discriminative information from opposite 1/2 of body
Trigeminal lemniscus: conveys pain, temperature, and crude tactile sensations from opposite 1/2 of face
Lateral lemniscus: conveys bilateral auditory information but predominantly info from opposite ear
Medial longitudinal fasciculus: conveys vestibular influences to cranial nerve III, IV, VI and fibers from oculomotor system
Descending tract of V: ipsilateral pain/temp analgesia from 1/2 face
Corticospinal tract: conveys descending motor info from motor cortex
Corticobulbar tract: innervates brainstem cranial nerve motor nuclei