Posterior compartment of the arm
Encyclopedia
The posterior compartment of the arm is an anatomic compartment which contains muscles which are all supplied by the radial nerve
. This compartment is also known as the "extensor compartment", extension
being its main action.
Radial nerve
The radial nerve is a nerve in the human body that supplies the upper limb. It supplies the medial and lateral heads of the triceps brachii muscle of the arm, as well as all 12 muscles in the posterior osteofascial compartment of the forearm and the associated joints and overlying skin.It...
. This compartment is also known as the "extensor compartment", extension
Extension (kinesiology)
In kinesiology, extension is a movement of a joint that results in increased angle between two bones or body surfaces at a joint. Extension usually results in straightening of the bones or body surfaces involved. For example, extension is produced by extending the flexed elbow. Straightening of...
being its main action.
Contents
The muscles of this compartment are the triceps brachii and anconeus muscle.- The triceps brachii is a large muscle containing three heads (lateral, medial, and middle).
- The anconeus is a small muscle that stabilizes the elbow joint during movement. Some embryologistsEmbryologyEmbryology is a science which is about the development of an embryo from the fertilization of the ovum to the fetus stage...
consider it as the fourth head of the triceps brachii. As the upper and lower limbs have similar embryological origins and the lower limb contains the quadriceps femoris muscle (the lower limb equivalent of the triceps), which has four heads, this would seem to make sense.
External links
- Dissection at tufts.edu
- http://anatomy.med.umich.edu/musculoskeletal_system/axilla_ans.html