What Is The Position of The Arm With An Erb's Palsy?: Hide Related Topic Details
What Is The Position of The Arm With An Erb's Palsy?: Hide Related Topic Details
What Is The Position of The Arm With An Erb's Palsy?: Hide Related Topic Details
Erb's palsy may result from a lesion of the upper trunk (C5-C6) of the brachial plexus.
Injury to roots C5 and C6 affects the
musculocutaneous (C5-C7), axillary (C5-
C6), median (C5-T1), and radial (C5-T1)
nerves.
Wrist extensors: Extensor carpi radialis longus, extensor carpi radialis brevis,
extensor carpi ulnaris
Real Texans Drink Cold Beer to remember the proximal-to-distal organization of the
brachial plexus: Roots Trunks Divisions Cords Branches
5 Roots: ventral rami of C5, C6, C7, C8, T1
3 Trunks:
Superior (upper) trunk (C5, C6)
6 Divisions: There is an anterior and posterior division for each of the 3 trunks.
There are 3 Cords (named according to their anatomic relationship to the axillary artery):
Posterior cord Axillary nerve, radial nerve
Lateral cord
Musculocutaneous nerve, part of
median nerve
Axillary nerve
Radial nerve
Median nerve
Ulnar nerve
Wrist extensors: Extensor carpi radialis longus, extensor carpi radialis brevis,
extensor carpi ulnaris
Klumpke's palsy may result from a lesion of the lower trunk (C8-T1) of the brachial
plexus. It is an extremely rare injury and can be caused by a forceful combination of arm
traction and abduction during delivery.
Note: Although lower trunk lesions are typically presented as obstetrical complications,
adults may sustain the injury by grasping for a ledge when falling from height. Examples
include grasping for the top rung of a ladder when falling or grabbing a tree branch when
falling from above.
Affects the wrist flexors and the intrinsic muscles of the hand presenting as a claw hand:
Intrinsics: Hyperextension at MCP joint and flexion at DIP and PIP due to loss
of lumbricals and interossei
Note: Sources will vary on the precise presentation of Klumpke's palsy due to variable
degrees of median nerve damage.
Injury of C8-T1 may also involve the sympathetic trunk/ganglia and is called Horner's
syndrome:
Miosis
Anhidrosis
Ptosis
Winged scapula: A winged scapula is caused by a lesion of the long thoracic nerve.
Wall test: The patient stands facing wall with palms flat against the wall and pushes
forward; a positive test is winging of the scapula.
The serratus anterior is innervated by the long thoracic nerve, formed by ventral rami
of spinal nerves C5, C6, C7.
Actions of serratus anterior:
Protraction of scapula Anterior rotation of the scapula around the ribs
observed during a "punching" motion
Medial winging of the scapula Inferior scapular angle is rotated medially and
lifted superiorly and away from the posterior thoracic wall, which may be
accentuated by having the patient push against a wall with flat palms (see image)
Compare:
Lesion of accessory nerve (CN XI) (eg, radical neck dissection) causes paralysis of trapezius:
Drooping of the shoulder
Lateral scapular winging Inferior scapular angle is rotated laterally and lifted
superiorly and away from the posterior thoracic wall, which may be accentuated
during resisted abduction.