01/09/2025
The major nerves of the upper limb (arm, forearm, and hand) and the muscles they supply. These nerves are responsible for motor control (movement) and sensory function (feeling). Let’s break it down:
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1. Radial Nerve (red in the diagram)
Runs along the posterior arm and forearm.
Motor supply: Mainly the extensor muscles of the forearm (straightening wrist and fingers).
Muscles shown:
Brachioradialis – helps in elbow flexion.
ECRL (Extensor Carpi Radialis Longus) – wrist extension.
ED (Extensor Digitorum) – finger extension.
ECM (Extensor Carpi Ulnaris) – wrist extension/adduction.
APL (Abductor Pollicis Longus) – thumb abduction.
EPL (Extensor Pollicis Longus) – thumb extension.
Ei (Extensor Indicis) – index finger extension.
Supinator – rotates forearm outward (supination).
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2. Median Nerve (yellow in the diagram — though here labeled incorrectly as "Relial Nerve")
(Likely a typo in the image, it should be Median Nerve)
Runs through the forearm and into the hand.
Motor supply: Mainly the flexor muscles of the forearm and thumb muscles.
Muscles shown:
PL (Palmaris Longus) – wrist flexion.
FDS (Flexor Digitorum Superficialis) – finger flexion (middle phalanges).
FPQ, FPB (Flexor Pollicis Longus & Brevis) – thumb flexion.
OP (Opponens Pollicis) – thumb opposition.
APL, Ei – thumb & finger movement.
Lumbricals 1 & 2 – finger flexion at MCP joints, extension at IP joints.
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3. Ulnar Nerve (blue in the diagram)
Runs along the inner arm ("funny bone nerve").
Motor supply: Mostly hand muscles, especially fine control.
Muscles shown:
FCU (Flexor Carpi Ulnaris) – wrist flexion/adduction.
FDP (medial half of Flexor Digitorum Profundus) – flexes ring & little finger tips.
ADM (Abductor Digiti Minimi) – little finger abduction.
FDMB (Flexor Digiti Minimi Brevis) – flexion of little finger.
ODM (Opponens Digiti Minimi) – opposition of little finger.
Adductor Pollicis – adducts thumb.
Palmar & Dorsal Interossei – finger abduction/adduction.
Lumbricals 3 & 4 – flexion/extension movements in little & ring finger.
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🔑 Key Takeaways:
Radial nerve → Extensors (posterior muscles, wrist/finger extension).
Median nerve → Flexors (forearm flexors, thumb opposition, first 2 lumbricals).
Ulnar nerve → Fine hand control (intrinsic hand muscles, last 2 lumbricals, interossei).