What is the lumbosacral enlargement of spinal cord?
The lumbar enlargement of the spinal cord corresponds to the mild increase in cross sectional area of the cord from the T11 level to the conus medullaris. It is enlarged due to the presence of the spinal nerve anterior rami which contribute to the lumbar and sacral plexuses.
Why is the cervical and lumbar regions enlarged?
Two regions of the spinal cord are enlarged to accommodate the greater number of nerve cells and connections needed to process information related to the upper and lower limbs (see Figure 1.10B).
At what spinal levels is the lumbosacral enlargement?
Lumbar enlargement comprises the spinal cord segments from L2 to S2, and is found about the vertebral levels T9 to T12.
What are the two regions of enlargement in the spinal cord?
Two enlargements of the spinal cord can be visualized: The cervical enlargement, which extends between C3 to T1; and the lumbar enlargements which extends between L1 to S2 (Figure 3.1). The cord is segmentally organized.
What is the function of lumbosacral enlargement?
The lumbar enlargement gives attachment to the nerves which supply the lower limbs. It commences about the level of the ninth thoracic vertebra, and reaches its maximum circumference, of about 33 mm, opposite the last thoracic vertebra, below which it tapers rapidly into the conus medullaris.
What is the structure of spinal cord?
Spinal cord and nerves: The spinal cord is a column of nerves that travels through the spinal canal. The cord extends from the skull to the lower back. Thirty-one pairs of nerves branch out through vertebral openings (the neural foramen). These nerves carry messages between the brain and muscles.
What is enlargement in anatomy?
Anatomical terminology The lumbar enlargement (or lumbosacral enlargement) is a widened area of the spinal cord that gives attachment to the nerves which supply the lower limbs. It commences about the level of T11 and ends at L2, and reaches its maximum circumference, of about 33 mm.
What is the cause of cervical enlargement?
It extends from about the fifth cervical to the first thoracic vertebra, its maximum circumference (about 38 mm.) being on a level with the attachment of the sixth pair of cervical nerves. The reason behind the enlargement of the cervical region is because of the increased neural input and output to the upper limbs.
What nerves emerge just below the lumbar enlargement?
Summary. Autonomic preganglionic neurons are concentrated in two intermediolateral columns running down the thoracic cord into the first few lumbar segments (sympathetic) and in the segments immediately below the lumbar enlargement (parasympathetic).
What are the 31 pairs of spinal nerves?
In humans there are 31 pairs: 8 cervical, 12 thoracic, 5 lumbar, 5 sacral, and 1 coccygeal. Each pair connects the spinal cord with a specific region of the body. Near the spinal cord each spinal nerve branches into two roots.
What causes enlargement of the spinal cord?
As the spinal cord is shorter in length than the vertebral column, it extends from the C3 to T1/T2 vertebral levels, its greatest circumference (approximately 38 mm) at the C6 level. The cervical enlargement is a result of the increased volume of motor cells in the ventral horns of the grey matter.
How big is the enlargement of the lumbar disc?
Lumbar Enlargement. The lumbar enlargement is 8 cm long from T9 to T12 and in continuity with the conus medullaris, which tapers off at the level of the L1–2 disc space into the filum terminale, an atrophic remnant of the caudal segment of the embryonic spinal cord.
How does the lumbar enlargement affect the legs?
Stimulation of the lumbar enlargement could produce rhythmic muscle activation in the legs leading to leg motion that resembled running. The two legs could both be involved, moving in phase or out of phase, or the rhythmic activity could be limited to one leg and, sometimes, even to one joint.
How big is the lumbar region of the spinal cord?
The lumbar enlargement is 8 cm long from T9 to T12 and in continuity with the conus medullaris, which tapers off at the level of the L1–2 disc space into the filum terminale, an atrophic remnant of the caudal segment of the embryonic spinal cord.
How are neurons organized in the lumbar enlargement?
The general organization of spinal neurons was examined on thick transverse sections of the lumbar enlargement. As is shown in Figure 7.1, several groups of neurons can be easily recognized. The tip of the dorsal horn is cuffed by gray matter with a low neuronal density.