Brachial Plexus Lesions

Trinity Angoni

Brachial Plexus

What is the brachial plexus?

At the root of the neck, the nerves form a complicated plexus called the brachial plexus.

This allows the nerve fibers derived from different segments of the spinal cord to be arranged and distributed efficiently in different nerve trunks to the various parts of the upper limb.

The brachial plexus is formed in the posterior triangle of the neck by the union of the anterior rami of the fifth, sixth, seventh, and eighth cervical and the first thoracic spinal nerves

What is the brachial plexus?

The nerves entering the upper limb provide the following important functions:

sensory innervation to the skin and deep structures, such as the joints;

motor innervation to the muscles; influence over the diameters of the blood

vessels by the sympathetic vasomotor nerves;

sympathetic secretomotor supply to the sweat glands.

Lesions of the brachial plexus

Lesions in continuity: more than half of the lesions are of

this type and most are caused by traction

The nerve roots are affected between the intervetebral foramina and the clavipectoral fascia(postganglionic).

The lesions may be transient(neuropraxia) or if the axons degerates(axonotemesis)

Lesions with ruptured nerve roots

In more severe cases the nerves are disrupted at the same level.

Partial avulsion lesions Rarely, the posterior roots are

spared,so that there may be the paradox of muscle paralysis with preservation of sansation.

Complete avulsion lesions The nerve is avulsed from the cord

and surgical repair is impossible.

Erb’s Palsy/upper obstetrical palsy

The upper trunk of the plexus is affected(C5,C6)

Result: Wrist is flexed and pronated, and the

fingers flexed The elbow is extended and the

shoulder internally rotated giving a waiter’s tip deformity

Klumpke’s paralysis The small muscles of the

hand,including the hypothenar and thenar groups are waisted giving a claw hand deformity.

There is sensory loss on the medial side of the forearm and wrist

There is association with Horner’s syndrome

T1 root aloneThe t1 root may be solely affected and

give the following signs: Wasting of the small muscles of the hand

incuding the thenar Sensory loss on the medial side of the hand

only Lesions of this type are found in the

incomplete lower obsterical palsy, cervical spondylosis, cervical rib syndrome,neurofibromatosis,and apical and metastatic carcinoma.

References Clinical anatomy by regions

(Richard.S.Snell) Clinical orthopaedic

examination(Ronald McRae)

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