Nerve compression syndromes of the hand present with various signs and symptoms that correspond to the nerve involved and its anatomic distribution. There are three nerves and their corresponding branches that provide sensory and motor innervation to the hand that include the median, ulnar, and radial. An understanding of the anatomy and distribution of these nerves is paramount in distinguishing the various signs, and symptoms in nerve compression syndromes. The median nerve is a mixed motor and sensory nerve that forms from the convergence of the lateral and medial cords of the brachial plexus. It contains contributions from the anterior rami of C5-T1. It descends the anterior compartment of the arm alongside the brachial artery on the medial aspect. From there, it enters the forearm between the superficial and deep heads of the pronator teres muscle. At this point, it provides motor innervation to several muscles in the flexor compartment that include the pronator teres, flexor carpi radialis, palmaris longus, and the flexor digitorum superficialis. It continues to travel distally along the forearm between the flexor digitorum superficialis (FDS) and flexor digitorum profundus (FDP) muscles. As it continues distally, it gives off a branch called the anterior interosseous nerve, which supplies the deep forearm muscles that include: lateral half of the FDP that supply the second and third digits, flexor pollicis longus (FPL), and pronator quadratus. The median nerve then enters the hand via the carpal tunnel, along with the tendons of the FDS, FDP, and FPL. In the hand, it provides motor innervation to the flexor pollicis brevis (FPB), abductor pollicis brevis (APB), opponens pollicis, and the lateral two lumbricals. The sensory distribution of the median nerve supplies the palmar aspect of the lateral palm, palmar aspect of the lateral three and a half digits, and the dorsal aspect of the lateral three and a half digits distal to the PIP joint.  The ulnar nerve is a mixed motor and sensory nerve that forms from the ventral rami of C8 and T1. It descends the arm medial to the brachial artery. It then passes posterior to the medial epicondyle of the humerus, into a passageway known as the cubital tunnel. It enters the forearm between the humeral and ulnar heads of the flexor carpi ulnaris (FCU) and continues down the forearm between the FCU and FDP. As it courses through the forearm, it gives off motor branches to the following muscles: FCU, medial FDP that supply the fourth and fifth digits. It enters the wrist lateral to the tendon of the FCU and enters a tunnel known as Guyon’s canal. In this canal, it bifurcates into a sensory branch and deep motor branch. The sensory branch provides sensation to the palmar aspect of the medial hand, fifth digit, and medial aspect of the fourth digit. The motor branch innervates the hypothenar muscles (abductor digiti minimi, opponens digiti minimi, flexor digiti minimi, and the palmaris brevis), the adductor pollicis, the deep head of the flexor pollicis brevis, the two medial lumbricals, and the dorsal and palmar interossei. The radial nerve is a mixed motor and sensory nerve that originates from the ventral rami of C5-T1. After emerging from the axilla, it travels posteriorly along with the profunda brachii artery in the posterior compartment of the arm. It traverses through the spiral groove between the lateral and medial aspects of the triceps muscle and further descends to the front of the lateral condyle of the elbow. During this course, It gives off multiple sensory nerves (posterior cutaneous nerve of the arm, inferior lateral cutaneous nerve of the arm, and the posterior cutaneous nerve of the forearm) that supply the posterior aspect of the arm and forearm. It also provides motor innervation to the following muscles of the arm: triceps muscle, anconeus, lateral brachialis, brachioradialis, extensor carpi radialis longus (ECRL), and the extensor carpi radialis brevis (ECRB). At the level of the elbow, the radial nerve divides into the superficial (sensory) branch and the deep branch, also known as the posterior interosseous nerve (PIN). The superficial radial sensory nerve emerges between the brachioradialis and extensor carpi radialis longus (ECRL) and travels distally towards the wrist and supplies the lateral dorsum of the hands, dorsal thumb, and dorsal proximal digits of the second to fourth digits. The PIN innervates the extensor compartment of the forearm that includes: supinator, extensor digitorum, extensor digiti minimi, extensor carpi ulnaris (ECU), abductor pollicis longus, extensor pollicis longus (EPL), extensor pollicis brevis (EPB), and extensor indicis.