Upper trunk

Upper trunk
Details
Latin	truncus superior plexus brachialis
Identifiers
Dorlands /Elsevier	t_20/12826113
TA	A14.2.03.004
FMA	65216
Anatomical terms of neuroanatomy

The upper trunk (or superior trunk) is a trunk of the brachial plexus which derives from the C5 and C6 roots.

Damage to the upper trunk causes: Arm hangs by side, Elbow cannot flex, Arm medially rotated, Forearm pronated, ‘waiter’s tip’, Loss of sensation over deltoid (C5) and lateral upper limb (C6).

The suprascapular nerve (C5,C6) arises from the upper trunk of the brachial plexus beneath the fascial floor of the posterior triangle, before it passes beneath the transverse scapular ligament and round the lateral border of the scapular spine.

The musculocutaneous and median nerves derive largely from this trunk.

Nerves of the brachial plexus

Supraclavicular

root (dorsal scapular, long thoracic)
upper trunk (suprascapular, to the subclavius)

Infraclavicular

lateral cord	lateral pectoral musculocutaneous (lateral cutaneous of forearm) median/lateral root: anterior interosseous palmar recurrent common palmar digital (proper palmar digital)

medial cord	medial pectoral cutaneous: medial cutaneous of forearm medial cutaneous of arm ulnar: muscular palmar dorsal (dorsal digital nerves) superficial (common palmar digital, proper palmar digital) deep median/medial root: see above

posterior cord	subscapular (upper, lower) thoracodorsal axillary (superior lateral cutaneous of arm) radial: muscular cutaneous (posterior of arm, inferior lateral of arm, posterior of forearm) superficial (dorsal digital nerves) deep (posterior interosseous)

Other

cutaneous innervation of the upper limbs

Index of the peripheral nervous system

Description	Anatomy Nerves cranial trigeminal cervical brachial lumbosacral plexus somatosensory spinal autonomic Physiology reflexes proteins neurotransmitters transporters Development neurotrophins

Disease	Autonomic Congenital Injury Neoplasms and cancer Other Symptoms and signs eponymous

Treatment	Procedures Local anesthetics

Additional images

Brachial plexus.Deep dissection.
Brachial plexus.Deep dissection.Anterolateral view