Carpometacarpal Joint
Description
Other Names
- Carpometacarpal Joint
- CMC
- Trapeziometacarpal Joint
General
- Synovial joints formed by the articulation between the distal carpal bones (carpo-) and metacarpal bones (metacarpal-)
- There are 5 CMC joints (thumb and 4 additional digits)
Articulations
First CMC Joint
- Thumb joint (trapeziometacarpal joint) is the most specialized, flexible
- Articulation of trapezium, first metacarpal
- Characterized as a synovial, curved saddle joint
Second to Fifth CMC Joint
- 2nd CMC Joint: trapezium, trapezoid, capitate and second metacarpal
- 3rd CMC Joint: capitate and third metacarpal
- 4th CMC Joint: capitate, hamate and fourth metacarpal
- 5th CMC Joint: hamate and fifth metacarpal
Ligaments
First CMC Joint[4]
- Dorsal deltoid ligament complex of the thumb
- Posterior oblique carpometacarpal ligament
- Anterior oblique carpometacarpal ligament
- Lateral ligament
- Fibrous capsule
Second to Fifth CMC Joint
- Dorsal carpometacarpal ligaments
- Strongest; contribute most to joint stability
- Palmar carpometacarpal ligaments
- Interosseous ligament
Joint Capsule
First CMC Joint
- Characterized as a synovial, curved saddle joint
- Separate synovial membrane lines the fibrous joint capsule
Second to Fifth CMC Joint
- Synovial membranes are often continuous with those of the intercarpal joints
- 4th and 5th CMC Joints:
- May possess a shared synovial cavity, separated from the other carpometacarpal joints of the digits
- Due to extensions of the medial interosseous ligament into the palmar and dorsal parts of the capsule
Actions
First CMC Joint
- Flexion: opponens pollicis, flexor pollicis brevis, flexor pollicis longus
- Extension: abductor pollicis longus, extensor pollicis longus, extensor pollicis brevis
- Abduction: abductor pollicis longus, abductor pollicis brevis
- Adduction: adductor pollicis, extensor pollicis longus
- Opposition: Movement of thumb across palm to the digits
- Retroposition: elevation of the thumb into extension, ulnar adduction
- Circumduction: sequential occurrence of extension, abduction, flexion and abduction (or the reverse)
Second to Fifth CMC Joint
- Increasing range of motion moving from second to fifth[5]
- Minor movement occurs due contraction of FDS, FDP, and Extensor Digitorum
- 5th CMC Joint: considerable mobility, contraction of opponens digiti minimi generates flexion, lateral rotation
Vascular Supply
First CMC Joint
- First dorsal metacarpal branch of the radial artery
Second to Fifth CMC Joint
- Posterior carpal branch of the radial artery
- Posterior carpal branch of the ulnar artery
- Anterior interosseous artery
Innervation
First CMC Joint
- Lateral antebrachial cutaneous nerve
- Palmar cutaneous branch of the median nerve
- Superficial radial nerve (rarely)
Second to Fifth CMC Joint
- Dorsal ulnar nerve
- Anterior interosseous nerve
- Superficial radial nerve
Clinical Significance
See Also
References
- ↑ Ayhan, Çiğdem, and Egemen Ayhan. "Kinesiology of the wrist and the hand." Comparative kinesiology of the human body. Academic Press, 2020. 211-282.
- ↑ Image courtesy of wikpedia.org, "Carpometacarpal Joint"
- ↑ Vos, F. M., et al. "A statistical shape model without using landmarks." Proceedings of the 17th International Conference on Pattern Recognition, 2004. ICPR 2004.. Vol. 3. IEEE, 2004.
- ↑ Zhang AY, Van Nortwick S, Hagert E, Yao J, Ladd AL. Thumb carpometacarpal ligaments inside and out: a comparative study of arthroscopic and gross anatomy from the robert a. Chase hand and upper limb center at stanford university. (2013) Journal of wrist surgery. 2 (1): 55-62
- ↑ Drake R, Vogl AW, Mitchell AWM. Gray's Anatomy for Students. Churchill Livingstone. ISBN:B005YZX32I.