The dorsal branch of ulnar nerve arises about 5 cm. proximal to the wrist

Wrist

In human anatomy, the wrist is variously defined as 1) the carpus or carpal bones, the complex of eight bones forming the proximal skeletal segment of the hand;...

; it passes backward beneath the Flexor carpi ulnaris, perforates the deep fascia

Deep fascia

Deep fascia is a layer of fascia which can surround individual muscles, and divide groups of muscles into compartments....

, and, running along the ulnar side of the back of the wrist and hand, divides into two dorsal digital branches; one supplies the ulnar side of the little finger

Little finger

The little finger, often called the pinky in American English, pinkie in Scottish English , or small finger in medicine, is the most ulnar and usually smallest finger of the human hand, opposite the thumb, next to the ring finger.-Muscles:There are four muscles that...

; the other, the adjacent sides of the little and ring finger

Ring finger

The ring finger is the fourth digit of the human hand, and the second most ulnar finger, located between the middle finger and the little finger. It is also called digitus medicinalis, the fourth finger, digitus annularis, digitus quartus, or digitus IV in anatomy.- Etymology :According to László A...

s.

It also sends a twig to join that given by the superficial branch of the radial nerve

Radial nerve

The radial nerve is a nerve in the human body that supplies the upper limb. It supplies the medial and lateral heads of the triceps brachii muscle of the arm, as well as all 12 muscles in the posterior osteofascial compartment of the forearm and the associated joints and overlying skin.It...

 for the adjoining sides of the middle and ring fingers, and assists in supplying them.

A branch is distributed to the metacarpal region of the hand, communicating with a twig of the superficial branch of the radial nerve.