Median Neuropathy

Injury sites

When the distal humerus suffers supracondylar fracture (fracture just proximal to the epicondyles), both the median and ulnar nerves can be injured (more rarely the superficial sensory branch of the radial nerve can be, as well).
The median nerve can be ensnared in the humeral and ulnar heads of the pronator teres muscle as the median nerve exits the cubital fossa.
When the anterior interosseous nerve is injured in isolation (anterior interosseous syndrome or neuropathy), patients exhibit the "OK" sign; wherein, they are unable to form a circle with the thumb and index finger.

Neither the thumb's interphalangeal joint nor the index finger's distal interphalangeal joints will flex.

The most common compression site for the median nerve is the carpal tunnel at the wrist: the nerve passes beneath the flexor retinaculum through the carpal tunnel and is compressed.

Carpal Tunnel Syndrome

The median palmar cutaneous nerve, which enters the hand superficial to the carpal tunnel, so it's spared.
Laceration of the palm can injure the recurrent branch of the thumb in isolation.

Weakness

Median nerve injury produces lateral flexor weakness and thenar eminence (thumb pad) wasting, so-called "ape hand".

Claw Hand vs Ulnar Claw vs Benediction Sign

Hand deformities are best distinguished by the imbalance between intrinsic hand muscles (lumbricals/interossei) and extrinsic flexors/extensors.

A true “claw hand” is classically due to a lower trunk (C8–T1) or medial cord lesion, affecting both median and ulnar contributions to intrinsic hand muscles, resulting in clawing of all digits at rest with MCP hyperextension and PIP/DIP flexion due to unopposed extensor digitorum and flexor digitorum profundus/superficialis.
In contrast, an ulnar claw (ulnar neuropathy, e.g., cubital tunnel or Guyon canal) produces clawing of the 4th and 5th digits at rest, as loss of ulnar-innervated lumbricals and interossei leaves the medial digits most affected; the 2nd and 3rd digits are relatively spared due to intact median nerve lumbricals.
The “hand of benediction” is seen in proximal median nerve injury and is elicited when the patient attempts to make a fist—there is failure to flex digits 1, 2, and 3 (due to loss of FDS, lateral FDP, and lumbricals), while digits 4 and 5 can still flex via ulnar innervation.
High-yield distinction: ulnar claw = deformity at rest (digits 4–5), whereas benediction sign = deficit with attempted flexion (digits 1–3).