Proximal part of the free upper limb between the shoulder and the elbow
This article is about the upper part of the limb in humans and other animals. For the British semiconductor and software design company, seeArm Holdings. For other uses, seeArm (disambiguation).
By anatomical definitions, thebones,ligaments andskeletal muscles of theshoulder girdle, as well as theaxilla between them, are considered parts of the upper limb, and thus also components of the arm. TheLatin termbrachium, which serves as aroot word for naming many anatomical structures, may refer to either the upper limb as a whole or to the upper arm on its own.[3][4][5]
The radial nerve, which is from the fifth cervical spinal nerve to the first thoracic spinal nerve, originates as the continuation of the posterior cord of the brachial plexus. This nerve enters thelower triangular space (an imaginary space bounded by, amongst others, the shaft of the humerus and the triceps brachii) of the arm and lies deep to the triceps brachii. Here it travels with thedeep artery of the arm, which sits in theradial groove of the humerus. This fact is very important clinically as a fracture of the shaft of the bone here can causelesions or even transections in the nerve.
Other nerves passing through give no supply to the arm. These include:
Themedian nerve, nerve origin C5-T1, which is a branch of the lateral and medial cords of thebrachial plexus. This nerve continues in the arm, travelling in a plane between the biceps and triceps muscles. At the cubital fossa, this nerve is deep to thepronator teres muscle and is the most medial structure in the fossa. The nerve passes into theforearm.
The main artery in the arm is thebrachial artery. This artery is a big continuation of theaxillary artery. The point at which the axillary becomes the brachial is distal to the lower border of teres major. Thebrachial artery gives off an unimportant branch, thedeep artery of arm. This branching occurs just below the lower border ofteres major.
The brachial artery continues to thecubital fossa in the anterior compartment of the arm. It travels in a plane between thebiceps andtriceps muscles, the same as themedian nerve andbasilic vein. It is accompanied byvenae comitantes (accompanying veins). It gives branches to the muscles of the anterior compartment. The artery is in between themedian nerve and the tendon of thebiceps muscle in thecubital fossa. It then continues into theforearm.
The deep artery of the arm travels through thelower triangular space with theradial nerve. From here onwards it has an intimate relationship with the radial nerve. They are both found deep to the triceps muscle and are located on the spiral groove of thehumerus. Therefore,fracture of the bone may not only lead to lesion of theradial nerve, but alsohaematoma of the internal structures of the arm. The artery then continues on toanastamose with therecurrent radial branch of thebrachial artery, providing a diffuse blood supply for theelbow joint.
The veins of the arm carry blood from the extremities of the limb, as well as drain the arm itself. The two main veins are thebasilic and thecephalic veins. There is a connecting vein between the two, themedian cubital vein, which passes through thecubital fossa and is clinically important forvenepuncture (withdrawing blood).
The basilic vein travels on the medial side of the arm and terminates at the level of the seventh rib.
The cephalic vein travels on the lateral side of the arm and terminates as the axillary vein. It passes through thedeltopectoral triangle, a space between the deltoid and the pectoralis major muscles.
In Hindu, Buddhist and Egyptian iconography the symbol of the arm is used to illustrate the power of the sovereign. In Hindu tradition gods are depicted with several arms which carry specific symbols of their powers. It is believed that several arms depict omnipotence of gods. In popular culture Thakur did not have arms in the movie Sholay.
In West Africa, the Bambara use forearm to symbolize the spirit, which is a link between God and man.
Three North Koreans surrender toUSS Manchester by raising their arms
Symbolic gestures of raising both hands signal surrender, appeals for mercy, and justice.[12]
The arm, as can be seen here, formed one component ofhieroglyphs
In other animals, the termarm can also be used for homologous or analogous structures (such as one of the pairedforelimbs of afour-legged animal or thearms of cephalopods, respectively). In anatomical usage, the termarm may[3] sometimes refer specifically to the segment between the shoulder and the elbow,[14][15] while the segment between the elbow andwrist is theforearm. However, in common, literary, and historical usage,arm refers to the entire upper limb from shoulder to wrist. This article uses the former definition; seeupper limb for the wider definition.[8]
In primates, the arm is adapted for precise positioning of thehand and thus assist in the hand's manipulative tasks. The ball and socket shoulder joint allows for movement of the arms in a wide circular plane, while the structure of the two forearm bones which can rotate around each other allows for additional range of motion at that level.[16]
^abDrake, Richard L. (Richard Lee) (15 November 2015).Gray's anatomy for students. Vogl, Wayne; Mitchell, Adam W. M.; Gray, Henry (Third ed.). Philadelphia, PA.ISBN9780702051319.OCLC881508489.{{cite book}}: CS1 maint: location missing publisher (link)
^Moore, Keith L. (2013-02-13).Clinically oriented anatomy. Dalley, Arthur F., II,, Agur, A. M. R. (Seventh ed.). Philadelphia.ISBN978-1451119459.OCLC813301028.{{cite book}}: CS1 maint: location missing publisher (link)
^Standring, Susan, ed. (2016).Gray's anatomy : the anatomical basis of clinical practice (Forty-first ed.). [Philadelphia].ISBN9780702052309.OCLC920806541.{{cite book}}: CS1 maint: location missing publisher (link)
