Cervical rib
Encyclopedia
A cervical rib is a supernumerary
(or extra) rib
which arises from the seventh cervical vertebra. It is a congenital abnormality located above the normal first rib. A cervical rib is present in only about 1 in 500 (0.2%) of people; in even rarer cases, an individual may have two cervical ribs. Cervical ribs are sometimes known as "neck ribs".
due to compression of the lower trunk of the brachial plexus
or subclavian artery
. These structures are entrapped between the cervical rib and scalenus muscle.
Compression of the brachial plexus may be identified by weakness of the muscles around the muscles in the hand, near the base of the thumb. Compression of the subclavian artery is often diagnosed by finding a positive Adson's sign
on examination, where the radial pulse
in the arm is lost during abduction and external rotation of the shoulder.
It is under scientific debate to what degree children born with cervical ribs develop early childhood cancer at a higher rate than the general population . The Hox genes that control the development of cervical vertebrae are believed to play a role in suppressing cancer.
were nearly 4 meters long.
In birds, the cervical ribs are small and completely fused to the vertebrae.
In mammals the ventral parts of the transverse processes of the cervical vertebrae are the fused-on cervical ribs.
Supernumerary body part
Supernumerary body parts are most commonly a congenital disorder involving the growth of an additional part of the body and a deviation from the body plan. Body parts may be easily visible or hidden away, such as internal organs....
(or extra) rib
Rib
In vertebrate anatomy, ribs are the long curved bones which form the rib cage. In most vertebrates, ribs surround the chest, enabling the lungs to expand and thus facilitate breathing by expanding the chest cavity. They serve to protect the lungs, heart, and other internal organs of the thorax...
which arises from the seventh cervical vertebra. It is a congenital abnormality located above the normal first rib. A cervical rib is present in only about 1 in 500 (0.2%) of people; in even rarer cases, an individual may have two cervical ribs. Cervical ribs are sometimes known as "neck ribs".
Associated conditions
The presence of a cervical rib can cause a form of thoracic outlet syndromeThoracic outlet syndrome
Thoracic outlet syndrome is a syndrome involving compression at the superior thoracic outlet involving compression of a neurovascular bundle passing between the anterior scalene and middle scalene...
due to compression of the lower trunk of the brachial plexus
Brachial plexus
The brachial plexus is a network of nerve fibers, running from the spine, formed by the ventral rami of the lower four cervical and first thoracic nerve roots...
or subclavian artery
Subclavian artery
In human anatomy, the subclavian arteries are two major arteries of the upper thorax , below the clavicle . They receive blood from the top of the aorta...
. These structures are entrapped between the cervical rib and scalenus muscle.
Compression of the brachial plexus may be identified by weakness of the muscles around the muscles in the hand, near the base of the thumb. Compression of the subclavian artery is often diagnosed by finding a positive Adson's sign
Adson's sign
Adson's sign is seen when the head is turned to the side during deep inspiration, when there is loss of the radial pulse in the arm.It is sometimes used as a sign of thoracic outlet syndrome .It is named for Alfred Washington Adson....
on examination, where the radial pulse
Pulse
In medicine, one's pulse represents the tactile arterial palpation of the heartbeat by trained fingertips. The pulse may be palpated in any place that allows an artery to be compressed against a bone, such as at the neck , at the wrist , behind the knee , on the inside of the elbow , and near the...
in the arm is lost during abduction and external rotation of the shoulder.
It is under scientific debate to what degree children born with cervical ribs develop early childhood cancer at a higher rate than the general population . The Hox genes that control the development of cervical vertebrae are believed to play a role in suppressing cancer.
In other vertebrates
Many vertebrates, especially reptiles, have cervical ribs as a normal part of their anatomy rather than a pathological condition. Some sauropods had exceptionally long cervical ribs; those of Mamenchisaurus hochuanensisMamenchisaurus
Mamenchisaurus was a plant-eating four-legged dinosaur, known for its remarkably long neck which made up half its total length. It is known from numerous species which ranged in time from 160 to 145 million years ago, from the Oxfordian to Tithonian ages of the late Jurassic Period of...
were nearly 4 meters long.
In birds, the cervical ribs are small and completely fused to the vertebrae.
In mammals the ventral parts of the transverse processes of the cervical vertebrae are the fused-on cervical ribs.
