3.  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

4. 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.

5. 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)

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

7. Rarely, the posterior roots are spared,so
that there may be the paradox of muscle
paralysis with preservation of sansation.

8. The nerve is avulsed from the cord and
surgical repair is impossible.

9. 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

10. 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

11. The 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.

12. Clinical anatomy by regions
(Richard.S.Snell)
Clinical orthopaedic examination(Ronald
McRae)