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How blood reaches the cord: one anterior and two posterior spinal arteries running its length, topped up along the way by radiculomedullary arteries from the aorta, the largest being the artery of Adamkiewicz.

2–2 min · 3 sources

Where the spinal cord ends and what fills the canal below it. Why the cord stops near L1, how much that varies, and how the lower nerve roots travel down as the cauda equina.

2–2 min · 6 sources

The H-shaped core of the cord. Its horns sort sensory input, drive muscles and run autonomic outflow, and the dorsal horn is layered into laminae that receive different kinds of sensation.

1–2 min · 3 sources

The three membranes around the brain and cord and the fluid between them. What dura, arachnoid and pia are, where cerebrospinal fluid is made and where it goes, and why a lumbar puncture is done low in the back.

2–2 min · 2 sources

The strip of cortex in the precentral gyrus that starts voluntary movement. Its upper motor neurons send the corticospinal tract down to the cord, and its activity is what most brain–computer interfaces read.

3–3 min · 4 sources

The bands that tie the vertebrae together along the front, inside the canal and along the back. What each one joins, which movement it limits, and how they continue up to the skull.

2–2 min · 4 sources

The 31 pairs of mixed nerves that connect the cord to the body. How each forms from a sensory and a motor root, where it leaves the column, and how the nerves regroup into plexuses.

2–2 min · 2 sources

Where the skull meets the spine. The atlas carries the skull, the axis lets the head turn, and a small set of ligaments, above all the transverse ligament, holds the joints together.

2–2 min · 3 sources

The swelling on each dorsal root that holds the cell bodies of the body's sensory neurons. Why those neurons have a single split process, and what surrounds them.

1–1 min · 3 sources

The fibrocartilage pad between two vertebral bodies: a tough outer ring around a gel-like core. How it bears weight and lets the spine bend, how it changes with age, and what a herniated disc is.

2–2 min · 2 sources

Two lumbar vertebrae, the disc between them, the joints and ligaments that tie them, and the nerves that pass by. One of the two most common places for a disc to herniate, and a good place to see how bone, disc and nerve fit together.

3–3 min · 8 sources

The fused bones at the base of the column. The sacrum carries the weight of the trunk into the pelvis and lets the sacral nerves out through its foramina; the coccyx is the tailbone.

2–2 min · 2 sources

The part of the central nervous system inside the vertebral column. How it is built from grey horns and white columns, why it is shorter than the column, and how its regions are named.

3–3 min · 4 sources

The flexible stack of bones that carries the head and trunk, protects the spinal cord and lets the back move. Its five regions, its four curves and the parts every vertebra shares.

2–3 min · 2 sources

The main route for voluntary movement, from the motor cortex down through the brainstem, across the midline and down the cord to the lower motor neurons. Why a cut on one side of the cord weakens the same side below it.

4–5 min · 8 sources

The tracts that carry movement commands down the cord. The corticospinal tract for voluntary movement, and the extrapyramidal tracts from the brainstem for posture, balance, tone and corrections.

2–2 min · 3 sources

The route for fine touch, vibration and position sense. It climbs the back of the cord on the same side, crosses in the medulla and reaches the sensory cortex through the thalamus.

2–2 min · 2 sources

The cord's report to the cerebellum about where the body is. The cerebellum compares it with a copy of the motor command and corrects the movement.

1–2 min · 5 sources

The route for pain and temperature. Its fibres synapse as soon as they enter the cord and cross there, so a lesion of one side of the cord affects pain on the other side of the body.

2–2 min · 6 sources

The knee jerk explained. A stretched muscle's spindle makes the same muscle contract directly through the cord and relaxes its antagonist, keeping the muscle at a constant length.

2–2 min · 3 sources

Pulling away from a hot stove or a tack. Pain excites the motor neurons of the withdrawing muscle and, through an inhibitory interneuron, quiets the opposing muscle so the movement is faster.

1–2 min · 2 sources

Where the cord sends its automatic, involuntary commands. Sympathetic outflow leaves from the thoracic and upper lumbar cord, parasympathetic from the brainstem and sacral cord, and the bladder shows how both work with voluntary control.

2–3 min · 3 sources

How the brainstem's breathing rhythm reaches the diaphragm and rib muscles through the cord. Why the phrenic nerve's origin in the mid-neck matters after a spinal cord injury.

2–2 min · 4 sources

The spinal circuits that can produce the rhythm of stepping on their own. Graham Brown's half-centre idea, where the circuits sit, and why they matter for walking again after spinal cord injury.

2–2 min · 5 sources

The map from spinal segments to skin and muscle. How dermatomes and key muscles are used to find the level of a spinal cord injury in the standard examination.

1–2 min · 5 sources

Melzack and Wall's 1965 idea that the dorsal horn of the cord works like a gate on pain signals, opened or closed by other inputs and by the brain. What it proposed, what it changed, and how it is described now.

2–2 min · 3 sources

Why damage to one part of the cord's cross-section gives a recognisable pattern. Brown-Séquard, central cord, anterior cord and posterior cord patterns, explained from the tracts and the blood supply.

2–2 min · 6 sources

How the spine's side-view curves and the pelvis work together to keep the trunk balanced over the hips. Pelvic incidence, tilt and slope, the C7 plumb line, and how the body compensates when alignment is lost.

2–2 min · 4 sources

What happens when the cord is damaged, how the standard examination classifies the injury by level and completeness, which functions depend on the level, and what research is trying to restore.

2–2 min · 12 sources

How a neuron fires an all-or-none electrical pulse and sends it along its axon, why myelin makes it faster, and the Hodgkin–Huxley equations that describe it.

2–2 min · 3 sources

Why "L1" can mean two different places. The vertebrae and the spinal cord segments have their own numbering, and below the neck they drift apart, because the column grows longer than the cord.

3–3 min · 8 sources

Systems that read brain activity and turn it into commands, without using muscles. What they record, how the decoding works, how their speed is measured, and what the clinical trials so far do and do not show.

2–2 min · 9 sources

A digital bridge around a spinal cord injury. Implants read movement intentions from the cortex and turn them into stimulation of the lumbar cord, so that a person with paralysis can stand and walk under their own control.

2–2 min · 4 sources