Form the lower trunk of the brachial plexus. Intrinsic muscles of the hand receive all innervation from C8 and T1. T1 also gives rise to sympathetic nerve fibers.
C8 and T1 nerve roots form the lower trunk of the brachial plexus. The lower trunk contributes to the posterior and medial cords, which give rise to the axillary, radial, ulnar, and part of the median nerve.
Lower trunk damage may occur when physicians pull upwards on a baby’s abducted arm during delivery. stretching the axilla. This type of damage usually occurs with larger babies during vaginal deliveries. Other risk factors include gestational diabetes, prior large birth weight babies, small mothers with larger babies, overdue pregnancies, advanced maternal age, and excessive maternal weight gain during pregnancy often leads to larger babies.
Traumatic accidents to the the neck, such as whiplash from a car crash or grabbing a tree branch to break a fall, may stretch and damage lower trunk nerve roots of the brachial plexus, leading to Klumpke’s Palsy.
Traumatic accidents to the the neck, such as whiplash from a car crash or grabbing a tree branch to break a fall, may stretch and damage the lower trunk nerve roots of the brachial plexus, leading to Klumpke’s Palsy.
These muscles are exclusively innervated by the C8 and T1 nerve roots. The muscles of the thenar eminence, which are lumbricals 1 and 2, opponens pollicis, abductor pollicis brevis, and flexor pollicis brevis, are innervated by the distal median nerve. The interossei, lumbricals 3 and 4, and the hypothenar eminence muscles, including opponens digiti minimi, abductor digiti minimi, and flexor digiti minimi brevis, are innervated by the ulnar nerve.
When C8 and T1 nerve roots are damaged, the hand forms a total claw because the four lumbricals are unable to flex at the metacarpophalangeal joints or extend at the proximal and distal interphalangeal joints.
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