Product Code Database
Example Keywords: sweatshirt -cave $46-101
barcode-scavenger
   » » Wiki: Cervical Rib
Tag Wiki 'Cervical Rib'.
Tag
Cervical ribs are the of the in many . In most mammals, including humans, cervical ribs are not normally present as separate structures. They can, however, occur as a pathology. In humans, pathological cervical ribs are usually not of clinical concern, although they can cause a form of thoracic outlet syndrome.


Development
Like other ribs, the cervical ribs form by endochondral ossification.


Variation
The cervical ribs of were extended by ossified , and could reach exceptional lengths; a cervical rib of Mamenchisaurus sinocanadorum was long.

In , the cervical ribs are small and completely fused to the vertebrae.

In , the cervical ribs fully fuse with the cervical vertebrae to form part of the transverse processes, except in rare pathological cases. In contrast, retain the plesiomorphic condition of having separate cervical ribs.


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

Most cases of cervical ribs are not clinically relevant and do not have symptoms; cervical ribs are generally discovered incidentally, most often during and . However, they vary widely in size and shape, and in rare cases, they may cause problems such as contributing to thoracic outlet syndrome, because they press on the .

A cervical rib represents a persistent of the C7 lateral costal element. 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.


Diagnosis
On imaging, cervical ribs can be distinguished because their transverse processes are directed inferolaterally, whereas those of the adjacent thoracic spine are directed anterolaterally.
(2025). 9781853157547, Royal Society of Medicine.


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 or subclavian artery. These structures become encroached upon by the cervical rib and .

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 in the arm is lost during abduction and external rotation of the . 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.


In other animals
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 in human children, so it has given scientists new evidence to believe that the mammoth's extinction was attributed to the condition. They have also been interpreted as a sign of inbreeding depression in other mammals, such as .


External links
Page 1 of 1
1
Page 1 of 1
1

Account

Social:
Pages:  ..   .. 
Items:  .. 

Navigation

General: Atom Feed Atom Feed  .. 
Help:  ..   .. 
Category:  ..   .. 
Media:  ..   .. 
Posts:  ..   ..   .. 

Statistics

Page:  .. 
Summary:  .. 
1 Tags
10/10 Page Rank
5 Page Refs
1s Time