first rib
The first rib is the most superior of the twelve ribs. It is an atypical rib and is an important anatomical landmark and is one of the borders of the superior thoracic aperture.
Gross anatomy
Osteology
Compared to a typical rib, the first rib is short and thick and it has a single articular facet for the costovertebral joint. It is flattened from top to bottom. The first rib has a head, neck and shaft but lacks a discrete angle. The shaft is indented laterally, the groove for the subclavian artery, which contains the lowest brachial plexus trunk as well as the subclavian artery. Anterior to the scalene tubercle is another groove for the subclavian vein. There is no costal groove on its inferior surface. It has two tubercles:
- transverse tubercle: posterior and lateral to the neck; bears an articular facet for the transverse process of T1
- scalene tubercle: anteriorly between the grooves for the subclavian artery and vein; anterior scalene muscle inserts here
- it is also known as the Lisfranc tubercle, described by Lisfranc in 1815
Articulations
- costovertebral joint: articular facet on the head of the rib with a single articular facet on its own vertebral body
- costotransverse joint: articular facet on the transverse tubercle with the transverse process of T1
- costochondral joint: distal shaft with the first costal cartilage
Attachments
- anterior scalene muscle: scalene tubercle
- middle scalene muscle: between groove for the subclavian artery and transverse tubercle
- intercostal muscles: from the outer border
- subclavius muscle: arises from the distal shaft and first costal cartilage
- first digitation of the serratus anterior muscle
- parietal pleura: from the inner border
- costoclavicular ligament: anterior to the groove for the subclavian vein
- radiate ligament of head, from head to first thoracic vertebral body
- costotransverse ligaments: from non-articular facet of tubercle
Blood supply
- arterial: internal thoracic and superior intercostal arteries
- venous drainage: intercostal veins
Innervation
- first intercostal nerve
Relations
- superior: lower trunk of the brachial plexus, subclavian artery and vein, clavicle
- inferior: intercostal vessels and nerves, parietal pleura
- anterior: sympathetic trunk (over neck), supreme intercostal vein, superior intercostal artery, ventral T1 nerve root
- medial: contents of the superior thoracic aperture
- lateral: axillary artery and vein, divisions and cords of the brachial plexus
Variant anatomy
- osseous or fibrous articulation or fusion with a cervical rib
- bifid (forked) rib
- rudimentary (hypoplastic) rib: most commonly the first rib (0.2%)
- pseudoarthrosis of the first rib (0.1%)
Ossification
Ossified by 3 centers: 1 primary center for the shaft and 2 secondary centers - 1 for the head and 1 for the tubercle
Related pathology
The first rib, in particular, is involved in:
- thoracic outlet syndrome
- Pancoast tumor (this may also affect other superior ribs)
The first rib is also affected by pathology common to all ribs:
- infection, e.g. septic arthritis, osteomyelitis
- malignancy, e.g. chondrosarcoma, enchondroma, metastases
- trauma, e.g. fracture
- first rib fractures are often associated with clavicle fractures or damage to adjacent neurovascular structures
Siehe auch:
und weiter:
Assoziationen und Differentialdiagnosen zu erste Rippe:
