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# 2nd metacarpal

The second metacarpal is the palm bone of the index finger; it is the longest metacarpal and its base barely moves on the wrist.

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## What it is

The long bone in the palm leading to the index finger.

## What it does

Forms the palm and the knuckle at its head.

## Key points

- The longest metacarpal; its notched base locks around the trapezoid, so the index carpometacarpal joint barely moves
- Because the joint is fixed, index neck fractures tolerate much less angulation than those of the ring and little fingers
- The ECRL inserts on the back of its base and the flexor carpi radialis on the front

## Key facts

**Joints with**
Base: trapezium, trapezoid, capitate; head: proximal phalanx; adjacent metacarpals

**Landmarks**
Base, shaft, neck, head (knuckle)

## Relations

**Above**
[Trapezoid](https://durgical.com/en/anatomy/trapezoid/) mainly, with the [trapezium](https://durgical.com/en/anatomy/trapezium/) and [capitate](https://durgical.com/en/anatomy/capitate/) on each side

**Behind**
[ECRL](https://durgical.com/en/anatomy/extensor-carpi-radialis-longus/) tendon at the base; [extensor indicis](https://durgical.com/en/anatomy/extensor-indicis/) and [extensor digitorum tendons](https://durgical.com/en/anatomy/extensor-digitorum-tendons/) over the shaft

**In front**
[Flexor carpi radialis](https://durgical.com/en/anatomy/flexor-carpi-radialis/) insertion at the base; oblique head of the [adductor pollicis](https://durgical.com/en/anatomy/adductor-pollicis/); the [deep palmar arch](https://durgical.com/en/anatomy/deep-palmar-arch/) crosses the bases

**Lateral**
First dorsal interosseous; the [radial artery](https://durgical.com/en/anatomy/radial-artery/) enters the palm between it and the [1st metacarpal](https://durgical.com/en/anatomy/1st-metacarpal/)

**Medial**
First palmar interosseous and second dorsal interosseous

**Below**
[Proximal phalanx of the index finger](https://durgical.com/en/anatomy/proximal-phalanx-of-the-index-finger/)

## How to find it

The shaft is followed along the back of the hand from the index knuckle to its base, where a carpal boss may be felt.

## On imaging

PA, oblique and lateral views of the hand. On the PA view the 2nd to 5th carpometacarpal joints should show as even, parallel gaps; a lost or overlapping gap at the trapezoid suggests a CMC dislocation. Angulation of a neck fracture is judged on the lateral view. CT is used when a CMC fracture-dislocation is suspected but unclear on radiographs.

## Clinical notes

- Carpal boss at the base of the 2nd and 3rd metacarpals can irritate the overlying extensor tendons
- Base fractures can avulse the ECRL insertion and weaken wrist extension
- The radial artery dives into the palm between the bases of the 1st and 2nd metacarpals, a point at risk in dorsal approaches and base injuries of the index ray

## Development

The secondary ossification centre is at the head (distal), as in the 3rd to 5th metacarpals.

## Test yourself

Think of the answer, then tap the question to see it.

## Which is the longest metacarpal, and why does its carpometacarpal joint barely move?

The 2nd metacarpal; its notched base locks around the trapezoid.

## Why do 2nd metacarpal neck fractures tolerate less angulation than those of the ring and little fingers?

Its carpometacarpal joint is fixed, so it cannot compensate for angulation.

## Which tendons insert on the base of the 2nd metacarpal?

The extensor carpi radialis longus on the back and the flexor carpi radialis on the front.

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Educational information, not medical advice. For any symptom, see a health professional.

## Its names

**Official Latin (TA2)**
ossa metacarpi TA2 1264

**Official Spanish (DeCS)**
Hueso metacarpiano II

**English (TA2)**
2nd metacarpal

## Related

- [A1 pulleys](https://durgical.com/en/anatomy/a1-pulleys-of-the-flexor-tendon-sheaths/)
- [Adductor pollicis](https://durgical.com/en/anatomy/adductor-pollicis/)
- [Thumb base cartilage](https://durgical.com/en/anatomy/cartilage-of-the-thumb-carpometacarpal-joint/)
- [CMC ligaments](https://durgical.com/en/anatomy/carpometacarpal-and-metacarpal-ligaments/)
- [Deep transverse metacarpal ligament](https://durgical.com/en/anatomy/deep-transverse-metacarpal-ligament/)
- [Dorsal interossei](https://durgical.com/en/anatomy/dorsal-interossei/)
- [ECRL](https://durgical.com/en/anatomy/extensor-carpi-radialis-longus/)
- [Extensor tendons](https://durgical.com/en/anatomy/extensor-digitorum-tendons/)

Sources: Terminologia Anatomica (TA2); [Anatomy, Shoulder and Upper Limb, Hand Bones](https://www.ncbi.nlm.nih.gov/books/NBK547684/).

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Representative model, for educational purposes only.

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Source: https://durgical.com/en/anatomy/2nd-metacarpal/
License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/anatomy/2nd-metacarpal/