The enlargement of the spinal cord is the location where nerves that supply the upper limbs enter and leave the spinal cord, and the enlargement is the location where nerves that supply the lower limbs enter and leave the spinal cord.

1. Cervical

2. Lumbar

Explanation:

Spinal enlargements are the conspicuous regions in the spinal cord from where spinal nerves to and from limbs exit and enter respectively. Cervical enlargement is also called the superior enlargement. It starts from C4, the fourth cervical vertebra and extends to T1, the first thoracic vertebra. Cervical enlargement is the site from there the nerve that supplies to and come from the upper limbs arise.

Another enlargement is the lumbar enlargement. It is also called inferior enlargement or lumbosacral enlargement and extends from the ninth to the twelfth thoracic vertebra. It is the site from where the nerves to and from the lower limbs arise.

all these collisions do one thing, and that thing is explained in the last option. when dusst, rocks and ice collide, they harden and form giant layers of rocks or hard ice.

d)   to harden materials to form different parts of earth’s layers

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bioteacher101