Fourth thoracic
The trachea extends from the larynx to the vertebral level of the fifth thoracic vertebra (T5), where it bifurcates into the left and right main bronchi.
In an adult the lower end of the spinal cord usually ends at approximately the first lumbar vertebra, where it divides into many individual nerve roots (L1). That is the reason Lumbar Puncture usually perform at L3-L4 in order to prevent accidentally injure to the spinal cord. The point where the spinal cord ends is referred to as the "conus medullaris"
Lumbar Vertebra 3
Not much information here in context to efficiently answer the question but I will try. The spinal cord generally ends (terminates) around the L1 vertebral level in the lumbar spinal column give or take a level or so in normal humans. After this, small spinal nerves continue down in a sac and exit the lumbar and sacral spine to innervate the pelvis and lower extremities.
Conus medullaris is the lower end of the spinal cord. L1 is level 1 of the lumbar vertebral. T12 refers to the 12 thoracic pairs. It shows the position at the spinal cord where the conus medullaris ends.
between L4 and L5 because the spinal cord stops near L2 and a needle introduced below this level will miss the spinal cord and encounter only nerve roots, which are usually pushed aside.
The lumbar puncture must be done below the level of the spinal cord termination (conus medullaris), which is typically at the L1-L2 vertebral level in adults. Placing the needle below this point reduces the risk of spinal cord injury.
Spondylolyis is a condition where there is an injury (stress fracture or fracture) in the pars interarticularis of the posterior elements of the spine. Spondylolisthesis describes the anterior displacement of a vertebra or the vertebral column in relation to the vertebrae inferior to it. The forward translation of the vertebral body causes narrowing of the central spinal canal at the level of the slip.
Conus medullaris is the lower end of the spinal cord. L1 is level 1 of the lumbar vertebral. T12 refers to the 12 thoracic pairs. It shows the position at the spinal cord where the conus medullaris ends.
The spinal nerves exit from the vertebral column through openings between adjacent vertebrae. These openings, called intervertebral foramina, are located just in front of the facet joints. They exit from what are called intervertebral foramina (foramen means opening).
S3