Cervical rib

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Cervical rib
Other namesNeck ribs [1]
Halsrippe.png
Specialty Thoracic surgery

A cervical rib in humans is an extra rib which arises from the seventh cervical vertebra. Their presence is a congenital abnormality located above the normal first rib. A cervical rib is estimated to occur in 0.2% [2] to 0.5% [3] (1 in 200 to 500) of the population. [4] People may have a cervical rib on the right, left or both sides. [5] [6]

Contents

Most cases of cervical ribs are not clinically relevant and do not have symptoms; [7] [8] cervical ribs are generally discovered incidentally, most often during x-rays and CT scans. [3] [4] [6] However, they vary widely in size and shape, [3] and in rare cases, they may cause problems such as contributing to thoracic outlet syndrome, [7] because of pressure on the nerves that may be caused by the presence of the rib. [7] [9]

A cervical rib represents a persistent ossification of the C7 lateral costal element. [7] [8] During early development, this ossified costal element typically becomes re-absorbed. Failure of this process results in a variably elongated transverse process or complete rib that can be anteriorly fused with the T1 first rib below. [10]

Diagnosis

3D CT reconstruction of a cervical rib. Halsrippe.JPG
3D CT reconstruction of a cervical rib.
Bilateral, symmetric, full, ossified cervical ribs. CervicalRibs.png
Bilateral, symmetric, full, ossified cervical ribs.

On imaging, cervical ribs can be distinguished because their transverse processes are directed inferolaterally, whereas those of the adjacent thoracic spine are directed anterolaterally. [11]

Associated conditions

The presence of a cervical rib can cause a form of thoracic outlet syndrome due to compression of the lower trunk of the brachial plexus or subclavian artery. [7] These structures become encroached upon by the cervical rib and scalene muscles.

Compression of the brachial plexus may be identified by weakness of 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. [7] A positive Adson's sign is non-specific for the presence of a cervical rib however, as many individuals without a cervical rib will have a positive test. Compression of the sympathetic chain may cause Horner's syndrome.

Other animals

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 hochuanensis 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.

Recent studies have also found a high percent of cervical ribs in woolly mammoths. It is believed that the decline in mammoth numbers may have forced inbreeding within the species which in turn had increased the number of mammoths being born with cervical ribs. Cervical ribs have been connected with leukaemia in human children, so it has given scientists new evidence to believe that the mammoth's extinction was attributed to the condition. [12]

Related Research Articles

<span class="mw-page-title-main">Rib</span> Long bone in vertebrates that protects vital respiratory and cardiovascular organs

In vertebrate anatomy, ribs are the long curved bones which form the rib cage, part of the axial skeleton. In most tetrapods, 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. In some animals, especially snakes, ribs may provide support and protection for the entire body.

<span class="mw-page-title-main">Rib cage</span> Bone structure that protects the vital organs and major blood vessels

The rib cage is an endoskeletal enclosure in the thorax of most vertebrate animals that comprises the ribs, vertebral column and sternum, which protects vital organs such as the heart, lungs and great vessels. The circumferential enclosure formed by left and right rib cages, together known as the thoracic cage, is a semi-rigid bony and cartilaginous structure which surrounds the thoracic cavity and supports the shoulder girdles to form the core part of the axial skeleton.

<span class="mw-page-title-main">Brachial plexus</span> Network of nerves

The brachial plexus is a network of nerves formed by the anterior rami of the lower four cervical nerves and first thoracic nerve. This plexus extends from the spinal cord, through the cervicoaxillary canal in the neck, over the first rib, and into the armpit, it supplies afferent and efferent nerve fibers to the chest, shoulder, arm, forearm, and hand.

<span class="mw-page-title-main">Spinal nerve</span> Nerve that carries signals between the spinal cord and the body

A spinal nerve is a mixed nerve, which carries motor, sensory, and autonomic signals between the spinal cord and the body. In the human body there are 31 pairs of spinal nerves, one on each side of the vertebral column. These are grouped into the corresponding cervical, thoracic, lumbar, sacral and coccygeal regions of the spine. There are eight pairs of cervical nerves, twelve pairs of thoracic nerves, five pairs of lumbar nerves, five pairs of sacral nerves, and one pair of coccygeal nerves. The spinal nerves are part of the peripheral nervous system.

<span class="mw-page-title-main">Lumbar vertebrae</span> Five vertebrae between the pelvis and the rib cage

The lumbar vertebrae are, in human anatomy, the five vertebrae between the rib cage and the pelvis. They are the largest segments of the vertebral column and are characterized by the absence of the foramen transversarium within the transverse process and by the absence of facets on the sides of the body. They are designated L1 to L5, starting at the top. The lumbar vertebrae help support the weight of the body, and permit movement.

<span class="mw-page-title-main">Subclavian artery</span> Major arteries of the upper thorax, below the clavicle

In human anatomy, the subclavian arteries are paired major arteries of the upper thorax, below the clavicle. They receive blood from the aortic arch. The left subclavian artery supplies blood to the left arm and the right subclavian artery supplies blood to the right arm, with some branches supplying the head and thorax. On the left side of the body, the subclavian comes directly off the aortic arch, while on the right side it arises from the relatively short brachiocephalic artery when it bifurcates into the subclavian and the right common carotid artery.

<span class="mw-page-title-main">Levator scapulae muscle</span> Slender skeletal muscle at the back and side of the neck

The levator scapulae is a slender skeletal muscle situated at the back and side of the neck. It originates from the transverse processes of the four uppermost cervical vertebrae; it inserts onto the upper portion of the medial border of the scapula. It is innervated by the cervical nerves C3-C4, and frequently also by the dorsal scapular nerve. As the Latin name suggests, its main function is to lift the scapula.

<span class="mw-page-title-main">Thoracic outlet syndrome</span> Medical condition

Thoracic outlet syndrome (TOS) is a condition in which there is compression of the nerves, arteries, or veins in the superior thoracic aperture, the passageway from the lower neck to the armpit, also known as the thoracic outlet. There are three main types: neurogenic, venous, and arterial. The neurogenic type is the most common and presents with pain, weakness, paraesthesia, and occasionally loss of muscle at the base of the thumb. The venous type results in swelling, pain, and possibly a bluish coloration of the arm. The arterial type results in pain, coldness, and pallor of the arm.

<span class="mw-page-title-main">Pancoast tumor</span> Medical condition

A Pancoast tumor is a tumor of the apex of the lung. It is a type of lung cancer defined primarily by its location situated at the top end of either the right or left lung. It typically spreads to nearby tissues such as the ribs and vertebrae. Most Pancoast tumors are non-small-cell lung cancers.

<span class="mw-page-title-main">Adson's sign</span> Medical condition

Adson's sign is the loss of the radial pulse in the arm by rotating head to the ipsilateral side with extended neck following deep inspiration.

<span class="mw-page-title-main">Cervical vertebrae</span> Vertebrae of the neck

In tetrapods, cervical vertebrae are the vertebrae of the neck, immediately below the skull. Truncal vertebrae lie caudal of cervical vertebrae. In sauropsid species, the cervical vertebrae bear cervical ribs. In lizards and saurischian dinosaurs, the cervical ribs are large; in birds, they are small and completely fused to the vertebrae. The vertebral transverse processes of mammals are homologous to the cervical ribs of other amniotes. Most mammals have seven cervical vertebrae, with the only three known exceptions being the manatee with six, the two-toed sloth with five or six, and the three-toed sloth with nine.

<span class="mw-page-title-main">Thoracic vertebrae</span> Vertebrae between the cervical vertebrae and the lumbar vertebrae

In vertebrates, thoracic vertebrae compose the middle segment of the vertebral column, between the cervical vertebrae and the lumbar vertebrae. In humans, there are twelve thoracic vertebrae and they are intermediate in size between the cervical and lumbar vertebrae; they increase in size going towards the lumbar vertebrae, with the lower ones being much larger than the upper. They are distinguished by the presence of facets on the sides of the bodies for articulation with the heads of the ribs, as well as facets on the transverse processes of all, except the eleventh and twelfth, for articulation with the tubercles of the ribs. By convention, the human thoracic vertebrae are numbered T1–T12, with the first one (T1) located closest to the skull and the others going down the spine toward the lumbar region.

<span class="mw-page-title-main">Stellate ganglion</span>

The stellate ganglion is a sympathetic ganglion formed by the fusion of the inferior cervical ganglion and the first thoracic ganglion, which is present in 80% of individuals. Sometimes, the second and the third thoracic ganglia are included in this fusion.

<span class="mw-page-title-main">Superior thoracic aperture</span>

The superior thoracic aperture, also known as the thoracic outlet, or thoracic inlet refers to the opening at the top of the thoracic cavity. It is also clinically referred to as the thoracic outlet, in the case of thoracic outlet syndrome. A lower thoracic opening is the inferior thoracic aperture.

<span class="mw-page-title-main">Scalene muscles</span> Muscles on the sides of the neck

The scalene muscles are a group of three muscles on each side of the neck, identified as the anterior, the middle, and the posterior. They are innervated by the third to the eighth cervical spinal nerves (C3-C8).

<span class="mw-page-title-main">Ligamenta flava</span> Ligaments connecting the laminae of adjacent vertebrae

The ligamenta flava are a series of ligaments that connect the ventral parts of the laminae of adjacent vertebrae. They help to preserve upright posture, preventing hyperflexion, and ensuring that the vertebral column straightens after flexion. Hypertrophy can cause spinal stenosis.

<span class="mw-page-title-main">Subclavian nerve</span>

The subclavian nerve, also known as the nerve to the subclavius, is small branch of the upper trunk of the brachial plexus. It contains axons from C5 and C6. It innervates the subclavius muscle.

<span class="mw-page-title-main">Inferior cervical ganglion</span>

The inferior cervical ganglion is one of the three cervical sympathetic ganglia. It situated between the base of the transverse process of the last cervical vertebra and the neck of the first rib, on the medial side of the costocervical artery.

<span class="mw-page-title-main">Vertebral column</span> Bony structure found in vertebrates

The vertebral column, also known as the backbone or spine, is part of the axial skeleton. The vertebral column is the defining characteristic of a vertebrate in which the notochord found in all chordates has been replaced by a segmented series of bone: vertebrae separated by intervertebral discs. Individual vertebrae are named according to their region and position, and can be used as anatomical landmarks in order to guide procedures such as lumbar punctures. The vertebral column houses the spinal canal, a cavity that encloses and protects the spinal cord.

<span class="mw-page-title-main">Vertebra</span> Bone in the vertebral column

The spinal column, a defining synapomorphy shared by nearly all vertebrates, is a moderately flexible series of vertebrae, each constituting a characteristic irregular bone whose complex structure is composed primarily of bone, and secondarily of hyaline cartilage. They show variation in the proportion contributed by these two tissue types; such variations correlate on one hand with the cerebral/caudal rank, and on the other with phylogenetic differences among the vertebrate taxa.

References

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  10. E. McNally, B. Sandin & R. A. Wilkins (June 1990). "The ossification of the costal element of the seventh cervical vertebra with particular reference to cervical ribs". Journal of Anatomy . 170: 125–129. PMC   1257068 . PMID   2123844.
  11. Balan, Nisha Sharma, Anu (2008). Get through FRCR part 2B : rapid reporting of plain radiographs. London: Royal Society of Medicine. ISBN   978-1853157547.{{cite book}}: CS1 maint: multiple names: authors list (link)
  12. "Woolly Mammoths Suffered Major Birth Defects Before Extinction". IFLScience. 25 March 2014.