General Morphology DLA

Question 1

What nerves come from telencephalon?

Answer 1

Telencephalon

– CN I: olfactory nerves (olfactory bulb, olfactory tract, olfactory cortex)

Question 2

What nerves come from the diencephalon?

Answer 2

Diencephalon

– CN II: optic nerve (optic chiasm, optic tract, lateral geniculate body)

Question 3

What nerves come from the mesencephalon?

Answer 3

Mesencephalon (ventral)
– CN III: oculomotor nerve (interpeduncular fossa)

• Mesencephalon (dorsal)
– CN IV: trochlear nerve (caudal to inferior colliculi)

• Remaning brainstem (ventral)
– CN V (trigeminal nerve – pons
– CN VI (abducens nerve – ponto-medullary junction)
– CN VII (facial nerve – cerebellopontine angle angle)
– CN VIII (vestibulo-cochlear nerve – cerebellopontine angle)
– CN IX (glossopharyngeal nerve – postolivary sulcus)
– CN X (vagus nerve – postolivary sulcus)
– CN XI (spinal accessory nerve – postolivary sulcus)
– CN XII (hypoglossal nerve – medulla, preolivary sulcus)

Question 4

Why do cell bodies aggregate?

Answer 4

• Cell bodies aggregate centrally to form spinal grey matter. The anterior part of the butterfly-shaped grey structure is the anterior or ventral horn (largely motor in function). At some spinal levels (T1 – L2 and S2 – S4), the ventral horn enlarges laterally, creating a lateral or intermediate horn to accommodate autonomic function. The posterior grey matter forms a posterior or dorsal horn, which is largely sensory in function. In the middle of the spinal gray matter is the central canal, the narrow spinal extension of the ventricular system.
• The white matter contains the efferent (motor) and afferent (somatosensory) tracts (bundles of axons) that form three columns: Dorsal, lateral, and ventral. Surface landmarks:
• The anterior median fissure is located ventromedially. The anterolateral sulcus is located more laterally.

• The posterior median sulcus is located dorsomedially. The posterolateral sulcus is located on the dorsal surface of the spinal
cord.

Question 5

What are the meningeal layers of the spinal cord?

Answer 5

• Three meningeal layers surround the spinal cord: Dura mater, arachnoid, and pia mater. The pia expands laterally to form multiple paired denticulate ligaments, which attach to the arachnoid and dura, thereby lending support.

Question 6

What are the segments of the spinal cord?

Answer 6

The spinal cord has cervical, thoracic, lumbar, sacral, and coccygeal segments, with the each emitting sensory and motor nerves.

Question 7

What is the conus medularis?

Answer 7

• The caudal end of the cord is called the conus medullaris, and nerves exiting this structure form a nervous complex called the cauda equina (horse’s tail).
• The pia mater extends caudally from the tip of the conus medullares as a strand (filame terminale) to join with a dural filament that attaches to the coccyx.

Question 8

What are the denticulate ligaments?

Answer 8

• Denticulate ligaments are lateral extensions of spinal pia that fuse with the arachnoid and dura to further stabilize the spinal cord within the vertebral canal.