spinal cord

Where does the spinal cord begin and end in adults?

Begins at the medulla oblongata at the foramen magnum and typically ends around L1-L2 as the conus medullaris.

What are the major gross anatomical features of the spinal cord?

Cervical and lumbar enlargements, conus medullaris, cauda equina, filum terminale, and spinal nerves.

What are the cervical and lumbar enlargements?

areas where nerves servicing upper and lower limbs arise from spinal cord

What are the conus medullaris, cauda equina, and filum terminale?

Conus medullaris: tapered end of the spinal cord; cauda equina: bundle of spinal nerve roots below it; filum terminale: extension of pia mater that anchors the cord inferiorly.

What spaces surround the spinal meninges, and what do they contain?

Epidural: fat and blood vessels; subdural: potential space between dura and arachnoid; subarachnoid: CSF and blood vessels between arachnoid and pia.

How does the spinal epidural space differ from the cranial epidural space?

The spinal epidural space is a real space containing fat and vessels; the cranial epidural space is normally only a potential space.

Which meninx closely adheres to the spinal cord, and what special structures does it form?

Which meninx closely adheres to the spinal cord, and what special structures does it form?

What is a lumbar puncture, where is it performed, and why?

A needle is inserted into the subarachnoid space, usually between L3-L4 or L4-L5, to collect CSF or measure its pressure. It can help diagnose infections such as meningitis, bleeding, and certain neurological disorders.

Why is a lumbar puncture performed below L2 in adults?

The spinal cord typically ends at L1-L2, so the lower lumbar region reduces the risk of injuring the cord; the needle enters the CSF-containing space among the cauda equina roots.

What are the main structures visible in a spinal cord cross-section?

Central canal, gray matter, white matter, dorsal horns, ventral horns, lateral horns (where present), posterior median sulcus, and anterior median fissure.

. What is the central canal?

A small CSF-containing channel lined with ependymal cells that runs through the spinal cord.

What is found in spinal cord gray matter?

Neuron cell bodies, dendrites, synapses, and unmyelinated portions of axons; it is organized into horns.

What is found in spinal cord white matter?

Mainly myelinated axons organized into ascending sensory and descending motor tracts.

What neuron cell bodies are found in the dorsal horns?

Primarily multipolar interneurons and neurons involved in processing sensory input. The primary sensory neurons are pseudounipolar neurons whose cell bodies are in the dorsal root ganglia.

What neuron cell bodies are found in the ventral horns?

Multipolar somatic motor neurons that send axons to skeletal muscles.

What is found in the lateral horns?

Autonomic motor neuron cell bodies, particularly sympathetic preganglionic neurons in T1-L2 spinal cord segments.

How is a spinal nerve formed?

The dorsal root (sensory) and ventral root (motor) join to form a mixed spinal nerve.

What type of fibers are found in each root and nerve?

Dorsal root: sensory/afferent; ventral root: motor/efferent; spinal nerve: mixed sensory and motor fibers.

What are the dorsal and ventral rami, and what fibers do they contain?

Both are mixed branches containing sensory and motor fibers. Dorsal rami supply the deep back muscles and skin of the back; ventral rami supply the anterolateral trunk and limbs, forming nerve plexuses in most regions.

What type of neurons have their cell bodies in the dorsal root ganglia?

Pseudounipolar sensory neurons (structurally); they are afferent neurons (functionally).

What type of neurons have their cell bodies in the ventral horns?

Multipolar somatic motor neurons; they are efferent neurons.