the carpus
DESCRIPTION
TRANSCRIPT
THE CARPUS
The bones of the Carpus
Radius
Dorsal view
First row of carpals
Second row of carpals
CANNON and SPLINT BONES
radial carpal 2nd carpal
3rd carpal
accessory carpal
4th carpal
intermediate carpal
2nd metacarpal
Dorsal view
4th metatarsal
Palmar view
Anatomy
Dorsal view of the bottom row of carpal bones
UCICRC
4TH C
3RD C
2ND C
Muscles proximal to the carpus with tendons inserting at the joint
• Flexor carpi ulnaris• Flexor carpi lateralis
Schematic diagram of the musculoskeletal model used in this study.
Harrison S M et al. J Exp Biol 2010;213:3998-4009
©2010 by The Company of Biologists Ltd
Extensor carpi radialis m. Lateral Supracondylar
of Humer
us
Proximodorsal
on Metacarpal III
Radial n.
Extends
carpus
Ulnaris lateralis m. Lateral Epicondyle of Humer
us
Accessory
Carpal Bone
&Metacarpal IV
(Lateral Splint Bone)
Radial n.
Flexes carpus
Extensor carpi obliquus m.(Abductor pollicis longus m.)
Middle of
Radius, Craniolaterally
Proximal
Metacarpal II
(Medial Splint Bone)
Radial n.
Extends
carpus
Extensor carpi radialis: originates from the humerus, continues distally along the dorsal side of the radius, and inserts on the metacarpal tuberosity. Flexes the elbow, extends the carpus. Also used in the stay apparatus to fix the carpus.
Extensor carpi obliquus: originates from the radius and inserts into the top of the second metacarpal. Helps to extend the carpus.
Flexor carpi radialis: originates from the humerus and inserts into the proximal side of the second metacarpal. Flexes the elbow, extends the carpus.
Ulnaris lateralis: originates on the lateral side of the humerus, inserts into the accessory carpal bone and on the proximal side of the lateral splint bone. Flexes the carpus, extends the elbow.
Ligaments of the carpus
The Midcarpal Joint • Medial palmar intercarpal ligament (MPICL)• The lateral palmar intercarpal ligament (LPICL)• The dorsomedial intercarpal ligament (DMICL). • palmar intercarpal ligaments
Biomechanics
Medial viewLateral view
Carpal Joint Function
• To dissipate shock– Multiple cuboidal bone design allows for small
movements during load phases• Safer
– Rows of cuboidal bones making up a joint midway down the limb are advantageous for limbs that are made of a single column of bone.
• to allow for small movements of bones in 3 dimensions; – much greater shock dissipating ability – Better to compensate uneven footing
The advantages of a stack of cuboidal bones at the knee area depends on strong ligamentous
support throughout the support phase
Biomechanics
Over all direction of force on the carpus under load
SCL
ICL
Pathology
Pathology and Lameness
• Hygroma• Degenerative joint disease• Fractures of carpal bones• Soft tissue injury to ligaments• Torn tendons
