Neuroscience Clerkship

 

 
 

MAJOR MIXED NERVES

 

From the brachial and lumbosacral plexi, the major nerves of the upper and lower extremities are derived, respectively. There are several large mixed (i.e., containing motor and sensory fibers) nerves that every medical student should be familiar with.

 

 

Median Nerve

Root Derivation

C6-T1

Plexus Derivation

Upper, middle and lower trunks

Lateral and medial Cords

Major Motor Function

Wrist and finger flexion

Arm pronation

Thumb opposition and abduction

• Major Sensory Distribution

Volar thumb, index, middle and lateral ring fingers


 

Ulnar Nerve

Root Derivation

C8-T1

Plexus Derivation

Lower trunk

Medial cord

Major Motor Function

Intrinsic hand muscles

Distal finger flexion of ring and little fingers

Wrist flexion medially

• Major Sensory Distribution

Volar little finger and medial ring fingers


 

Radial Nerve

Root Derivation

C5-C8

Plexus Derivation

Upper, middle and lower trunks

Posterior cord

Major Motor Function

Elbow extension

Wrist and finger extension

Elbow flexion

• Major Sensory Distribution

Dorsal thumb, index, middle and lateral ring fingers

Posterior forearm and arm

Lateral arm


 

Musculocutaneous Nerve

Root Derivation

C5-C6

Plexus Derivation

Upper trunk

Lateral  cord

Major Motor Function

Elbow flexion

Arm supination

• Major Sensory Distribution

Lateral forearm


 

Axillary Nerve

Root Derivation

C5-C6

Plexus Derivation

Upper trunk

Posterior cord

Major Motor Function

Shoulder abduction and external rotation

• Major Sensory Distribution

Lateral shoulder


 

Femoral Nerve

Root Derivation

L2-L4

Plexus Derivation

Lumbar plexus

Major Motor Function

Knee extension

Hip flexion

• Major Sensory Distribution

Anterior and medial thigh

Medial calf


 

Sciatic Nerve

Root Derivation

L4-S3

Plexus Derivation

Lower lumbosacral plexus

Major Motor Function

Knee flexion

Ankle dorsiflexion and plantarflexion

Ankle inversion and eversion

• Major Sensory Distribution

Lateral and posterior calf

Dorsum and sole of the foot