arm

Information about arm

An arm is an upper limb of the body.

Arm (or arms) may also refer to: ARM may refer to: As an acronym:

See also

  • ARMS (disambiguation)
This article is about upper limb of an animal. For other uses, see ARM.


In anatomy, an arm is one of the upper limbs of an animal. The term arm can also be used for analogous structures, such as one of the paired upper limbs of a four-legged animal, or the arms of an octopus. Anatomically, the term arm refers specifically to the segment between the shoulder and the elbow. The segment between the elbow and wrist is the forearm. However, in colloquial speech the term arm often refers to the entire upper limb from shoulder to wrist.

In primates the arms are richly adapted for both climbing and for more skilled, manipulative tasks. The ball and socket shoulder joint allows for movement of the arms in a wide circular plane, while the presence of two forearm bones which can rotate around each other allows for additional range of motion at this level.
Enlarge picture
The human upper arm

Anatomy of the human arm

The human arm contains bones, joints, muscles, nerves, and blood vessels. Many of these muscles are used for everyday tasks.

Bony structure and joints

Enlarge picture
bone structure of a human arm


The humerus is the (upper) arm bone. It joins with the scapula above at the shoulder joint (or glenohumeral joint) and with the ulna and radius below at the elbow joint.

Elbow joint

Main article: Elbow-joint
The elbow joint is the hinge joint between the distal end of the humerus and the proximal ends of the radius and ulna. The upper arm bone is not easily broken. It is built to handle pressure of up to 300lbs.

Osteofascial compartments

The arm is divided by a fascial layer (known as lateral and medial intermuscular septa) separating the muscles into two osteofascial compartments: The fascia merges with the periosteum (outer bone layer) of the humerus. The compartments contain muscles which are innervated by the same nerve and perform the same action.

Two other muscles are considered to be partially in the arm:
  • The large deltoid muscle is considered to have part of its body in the anterior compartment. This muscle is the main abductor muscle of the upper limb and extends over the shoulder.
  • The brachioradialis muscle originates in the arm but inserts into the forearm. This muscle is responsible for rotating the hand so its palm faces forward (supination).

Cubital fossa

The cubital fossa is clinically important for venepuncture and for blood pressure measurement. It is an imaginary triangle with borders being: The structures which smell through the cubital fossa are vital. The order from which they pass into the forearm are as follows, from medial to lateral:

Nervous supply

The musculocutaneous nerve, from C5, C6, C7, is the main supplier of muscles of the anterior compartment. It originates from the lateral cord of the brachial plexus of nerves. It pierces the coracobrachialis muscle and gives off branches to the muscle, as well as to brachialis and biceps brachii. It terminates as the anterior cutaneous nerve of the forearm.

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 the lower 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 a deep artery of the arm (the profunda brachii), which sits in the radial groove of the humerus. This fact is very important clinically as a fracture of the bone at the shaft of the bone here can cause lesions or even transections in the nerve.

Other nerves passing through give no supply to the arm. These include:
  • The median nerve, nerve origin C5-T1, which is a branch of the lateral and medial cords of the brachial 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 the pronator teres muscle and is the most medial structure in the fossa. The nerve passes into the forearm.
  • The ulnar nerve, origin C7-T1, is a continuation of the medial cord of the brachial plexus. This nerve passes in the same plane as the median nerve, between the biceps and triceps muscles. At the elbow, this nerve travels posterior to the medial epicondyle of the humerus. This means that condylar fractures can cause lesion to this nerve.

Blood supply and venous drainage

Arteries

The main artery in the arm is the brachial artery. This artery is a continuation of the axillary artery. The point at which the axillary becomes the brachial is distal to the lower border of teres major. The brachial artery gives off an important branch, the profunda brachii (deep artery of the arm). This branching occurs just below the lower border of teres major.

The brachial artery continues to the cubital fossa in the anterior compartment of the arm. It travels in a plane between the biceps and triceps muscles, the same as the median nerve and basilic vein. It is accompanied by venae comitantes (accompanying veins). It gives branches to the muscles of the anterior compartment. The artery is in between the median nerve and the tendon of the biceps muscle in the cubital fossa. It then continues into the forearm.

The profunda brachii travels through the lower triangular space with the radial 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 the humerus. Therefore fracture of the bone may not only lead to lesion of the radial nerve, but also haematoma of the internal structures of the arm. The artery then continues on to anastamose with the recurrent radial branch of the brachial artery, providing a diffuse blood supply for the elbow joint.

Veins

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 the basilic and the cephalic veins. There is a connecting vein between the two, the median cubital vein, which passes through the cubital fossa and is clinically important for venepuncture (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 the deltopectoral triangle, a space between the deltoid and the pectoralis major muscles.

See also

Additional images


Cross-section through the middle of upper arm.


[1]

External links

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Human anatomical features
HEAD: Skull - Forehead – Eye – Ear – Nose – Mouth – Tongue – Teeth – Jaw – Face – Cheek – Chin NECK: Throat - Larynx – Adam's apple TORSO: Shoulders – Spine – Breast – Chest – Ribcage – Abdomen – Navel
:Sex organs (Clitoris/Vagina/Ovary/Uterus/Penis/Scrotum/Testicle) – Hip – Anus – Buttocks
LIMBS: Arm – Elbow – Forearm – Wrist – Hand – Finger (Thumb/Index/Middle/Ring/Little) – Leg – Lap – Thigh – Knee – Calf – Heel – Ankle – Foot – Toe (Hallux) SKIN: Hair
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General anatomy of upper limbs
Arm
Forearm
Hand
weapon is a tool used to injure, incapacitate, or kill an adversary.[1][2] Weapons may be used to attack and defend, and consequently also to threaten or protect. Metaphorically, anything used to damage (even psychologically) can be referred to as a weapon.
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arm is a narrow extension, inlet, or smaller reach, of water from a much larger body of water, like an ocean, sea, or lake. Although different geographically, a sound or bay may be called an arm.
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distributary, or a distributary channel, is a stream that branches off and flows away from a main stream channel. They are a common feature of river deltas. The phenomenon is known as river bifurcation. The opposite of a distributary is a tributary.
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coat of arms or armorial bearings (often just arms for short), in European tradition, is a design belonging to a particular person (or group of people) and used by them in a wide variety of ways.
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Motto
Մեկ Ազգ, Մեկ Մշակույթ   (Armenian)
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 Armenian}}} 
Writing system: Armenian alphabet 
Official status
Official language of: Armenia, Nagorno-Karabakh
Regulated by: National Academy of Sciences of Armenia
Language codes
ISO 639-1: hy
ISO 639-2: arm (B)
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The ARM architecture (previously, the Advanced RISC Machine, and prior to that Acorn RISC Machine) is a 32-bit RISC processor architecture developed by ARM Limited that is widely used in a number of embedded designs.
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ARM Limited

Public (LSE:  ARM , NASDAQ:  ARMHY )
Founded 1990
Headquarters Cambridge, England, UK

Key people Sir Robin Saxby, Warren East, Tim Score
Industry RISC Microprocessors
Products Processor IP; Physical IP
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Argentine peso moneda nacional
peso moneda nacional argentino (Spanish)
ISO 4217 Code ARM
User(s) Argentina

Superunit
5 argentino

Subunit
1/100 centavo
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adjustable rate mortgage (ARM) is a mortgage loan where the interest rate on the note is periodically adjusted based on an index.[1] This is done to ensure a steady margin for the lender, whose own cost of funding will usually be related to the index.
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Macular degeneration
Classification & external resources

ICD-10 H 35.3
ICD-9 362.5

MeSH D008268

Macular degeneration is a medical condition predominantly found in elderly adults in which the center of the inner lining of the eye,
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Direct action

ARM first emerged in the UK in the 1980s as animal-rights activists shifted their focus away from demonstrations and
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anti-radiation missile (ARM) is a missile which is designed to detect and home in on an enemy radio emission source. Typically these are designed for use against an enemy radar, although jammers and even radios used for communication can also be targeted in this manner.
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The Association of Radical Midwives (ARM) is a UK Organisation for Midwives, Doulas, Mothers, and anyone concerned with the health of maternity services.

ARM was created in 1976, and is a registered charity.
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The Association of Recovering Motorcyclists (.A.R.M.) is an independent motorcycle association that has existed since the mid 80's and currently has chapters in the United States, Canada, Australia, Sweden and Denmark. .A.R.M.
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Atmospheric Radiation Measurement (ARM) Program uses state-of-the-art active and passive remote sensing instrumentation to study the fundamental physics related to interactions between clouds and radiative feedback processes in the atmosphere.
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The Australian Republican Movement (ARM) is a non-partisan lobby group advocating constitutional change in Australia to a republican form of government.

History

Foundation


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An ÄRM is the name of an assortment of mystical objects in the anime and manga series MÄR: Marchen Awakens Romance.

Info

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ARMS may refer to:
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  • ARMs, a type of weapon in the Wild Arms video game franchise
  • Amherst Regional Middle School
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Anatomy (from the Greek ἀνατομία anatomia, from ἀνατέμνειν
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