T1 Nerve ◎

It provides sensation to the medial (inner) aspect of the forearm and the upper arm near the elbow.

: It is closely associated with the first rib and sits near the apex of the lung . Motor and Sensory Functions

T1 is the lowest (inferior) root of the brachial plexus. It contributes fibers to the Inferior Trunk of the plexus. From here, T1 fibers travel a long distance down the arm. They eventually form major peripheral nerves, including the Ulnar Nerve and the Median Nerve . t1 nerve

Immediately after exiting the foramen, the T1 nerve divides into two distinct pathways: the posterior ramus and the anterior ramus.

: From this trunk, fibers eventually travel into the ulnar nerve and the medial cord of the brachial plexus. It provides sensation to the medial (inner) aspect

Without T1 input, the hand becomes clumsy and weak, unable to perform fine motor tasks.

The T1 nerve root is the first of the thoracic spinal nerves, emerging from the spinal cord just below the T1 vertebra. It is a unique thoracic nerve because it serves as the lowest contributor to the , a complex network of nerves responsible for motor and sensory signals in the arms and hands. It contributes fibers to the Inferior Trunk of the plexus

When the T1 nerve is compressed or damaged—a condition known as —patients typically present with a specific cluster of symptoms: Hand motor functional deficits due to pure T1 radiculopathy

The T1 nerve is primarily responsible for "fine motor" control of the hands.

Because T1 carries the sympathetic fibers for the eye, injury to this nerve can result in Horner’s Syndrome. This is often seen in Pancoast tumors (lung cancer located at the apex of the lung) that invade the T1 nerve root.