[Durgical](https://durgical.com/en/) › [DurgiPedia](https://durgical.com/en/durgipedia/) › [Anatomy](https://durgical.com/en/anatomy/) › [Upper limb](https://durgical.com/en/anatomy/region/upper-limb/) › 1st metacarpal [Skeletal system](https://durgical.com/en/anatomy/system/skeletal-system/) · [Upper limb](https://durgical.com/en/anatomy/region/upper-limb/) # 1st metacarpal The first metacarpal is the palm bone of the thumb, from the wrist to the thumb knuckle; its short, mobile base lets the thumb oppose. [See in 3D →](https://durgical.app/?from=durgipedia&lang=en#region=upper_limb&select=metacarpal_1&side=r) Opens in the Durgical app, no sign-up needed. ## What it is The long bone in the palm leading to the thumb. ## What it does Forms the palm and the knuckle at its head. ## Key points - Bennett fracture: a two-part intra-articular fracture of the base; a small palmar-ulnar fragment stays held by the anterior oblique (beak) ligament while the APL pulls the shaft proximally and radially - Rolando fracture: a comminuted (Y- or T-shaped) intra-articular fracture of the base, with a worse outlook - The shortest and most mobile metacarpal: its saddle joint with the trapezium allows opposition of the thumb ## Key facts **Joints with** Base: trapezium (saddle joint); head: proximal phalanx **Landmarks** Base, shaft, neck, head (knuckle) ## Relations **Above** [Trapezium](https://durgical.com/en/anatomy/trapezium/) at the saddle joint, held by the [CMC ligaments](https://durgical.com/en/anatomy/carpometacarpal-and-metacarpal-ligaments/), including the anterior oblique (beak) ligament **Behind** APL tendon on the radial side of the base; the EPB and EPL tendons run down the back of the shaft **In front** [Opponens pollicis](https://durgical.com/en/anatomy/opponens-pollicis/) along the radial side of the shaft; the [FPL tendon](https://durgical.com/en/anatomy/flexor-pollicis-longus-tendon/) passes in front on its way to the thumb **Medial** First web space with the [adductor pollicis](https://durgical.com/en/anatomy/adductor-pollicis/) and the first dorsal interosseous (one head arises from it); the [radial artery](https://durgical.com/en/anatomy/radial-artery/) passes between it and the [2nd metacarpal](https://durgical.com/en/anatomy/2nd-metacarpal/) into the palm **Below** [Proximal phalanx of the thumb](https://durgical.com/en/anatomy/proximal-phalanx-of-the-thumb/) at the MCP joint, with the [thumb sesamoids](https://durgical.com/en/anatomy/sesamoid-bones-of-the-thumb/) and the [thumb UCL](https://durgical.com/en/anatomy/ulnar-collateral-ligament-of-the-thumb-mcp-joint/) ## How to find it Followed along the back of the thumb from the base, just distal to the anatomical snuffbox, to the head at the thumb knuckle; circling the thumb shows the carpometacarpal joint line. ## On imaging A true AP of the thumb (hand fully pronated) and a true lateral: a Bennett fracture shows a small fragment at the ulnar base with the shaft displaced; a Rolando fracture shows several fragments. ## Clinical notes - Bennett and Rolando fractures are unstable because of the pull of the APL and adductor pollicis and usually need reduction and fixation to protect the joint - Extra-articular base fractures tolerate more angulation than other metacarpal fractures, thanks to the mobile saddle joint ## Development Unlike the other metacarpals, its secondary ossification centre is at the base, as in a phalanx. ## Related conditions - [Fanconi anaemia](https://durgical.com/en/conditions/fanconi-anaemia/) - [De Quervain tenosynovitis](https://durgical.com/en/conditions/de-quervain-tenosynovitis/) ## Test yourself Think of the answer, then tap the question to see it. ## What is a Bennett fracture of the 1st metacarpal? A two-part intra-articular base fracture: a palmar-ulnar fragment stays held by the beak ligament while the abductor pollicis longus pulls the shaft away. ## How does a Rolando fracture of the 1st metacarpal differ from a Bennett fracture? It is a comminuted (Y- or T-shaped) intra-articular base fracture, with a worse outlook. ## Where is the secondary ossification centre of the 1st metacarpal? At the base, as in a phalanx, unlike the other metacarpals. [Add to my cards (3)](https://durgical.app/estudiar/?add=/en/anatomy/1st-metacarpal/) 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 I **English (TA2)** 1st metacarpal ## Related - [A1 pulleys](https://durgical.com/en/anatomy/a1-pulleys-of-the-flexor-tendon-sheaths/) - [APB](https://durgical.com/en/anatomy/abductor-pollicis-brevis/) - [Adductor pollicis](https://durgical.com/en/anatomy/adductor-pollicis/) - [APL](https://durgical.com/en/anatomy/abductor-pollicis-longus/) - [APL and EPB tendons](https://durgical.com/en/anatomy/abductor-pollicis-longus-and-extensor-pollicis-brevis-tendons/) - [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/) - [Dorsal interossei](https://durgical.com/en/anatomy/dorsal-interossei/) Sources: Terminologia Anatomica (TA2); [Anatomy, Shoulder and Upper Limb, Hand Bones](https://www.ncbi.nlm.nih.gov/books/NBK547684/). ## **Spotted a mistake?** We are always improving for the community. Tell us what is wrong and our team will review it. Report a mistake Representative model, for educational purposes only. --- Source: https://durgical.com/en/anatomy/1st-metacarpal/ License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/anatomy/1st-metacarpal/