upper arm
The upper arm ( lat. Brachium ) is a part of the arm and forms the proximal ( proximal ) portion of the upper limb . He is on the elbow with the lower arm and, via the shoulder joint to the shoulder girdle and the trunk .
Bony structures and articular surfaces
The upper arm of vertebrates contains only one bony structure, one of the longest and strongest tubular bones , the upper arm bone ( humerus ). Its almost hemispherical head ( caput humeri ) rests on the inside ( cranial-medial ) of the shaft and moves in the joint socket of the shoulder blade ( scapula ).
Adjacent joints
Shoulder joint
The shoulder joint ( articulatio humeri ) is the most flexible joint in humans. It is a ball- and- socket joint , the articular surfaces of which are formed by the humerus head (caput humeri) and the articular surface of the shoulder blade ( cavitas glenoidale scapulae ). Movements that the shoulder joint is capable of are spreading ( abduction ), leading ( adduction ), forward ( anteversion ) or flexion ( flexion ), backward movement ( retroversion ) or stretching ( extension ) as well as inward rotary movement and outwards ( internal and external rotation ).
Elbow joint
In the elbow joint ( articulatio cubiti ) the humerus, radius and ulna are connected to one another in three separate joints: the joint between the humerus and ulnar ( articulatio humeroulnaris ), the joint between the humerus and the radius ( articulatio humeroradialis ) and the joint between the ulna and ulna Radius ( articulatio radioulnaris proximalis ).
Musculature
Like other muscles, the muscles of the upper arm are each surrounded by a connective tissue covering ( fascia ). Another fascia, the so-called arm fascia ( Fascia brachii ), surrounds the upper arm muscles as a whole. A special feature of the upper arm is that there are also two septa ( septum intermusculare mediale and septum intermusculare laterale ), which extend between the humerus and arm fascia down to the top of the articular knot and define a flexor and extensor box. They also contain a number of nerves and vessels and serve as the surface of origin for muscles. Both partitions are pierced by nerves at certain points. Furthermore, the upper arm is moved by parts of the chest , back and shoulder muscles .
Overview
This table is only intended to provide an initial overview; more detailed descriptions can be found on the pages of the muscles concerned.
| Upper arm muscles | ||||||
|---|---|---|---|---|---|---|
| Pictures (the numbers correspond to those in the table) | ||||||
| Latin name | German name | origin | approach | Innervation | function | |
| Chest muscles | ||||||
| 1 | M. pectoralis major | Pectoralis major |
Clavicle , breastbone ( sternum ), sternum membrane / cartilage of ribs 2 to 6, anterior leaf of the rectus sheath |
Crista tuberculi majoris humeri |
N. pectoralis medialis , N. pectoralis lateralis |
Approach flexion inward rotation |
| 2 | M. serratus anterior | anterior sawtooth muscle | Upper eight ribs | Margo medialis, angulus inferior of the shoulder blade |
N. thoracicus longus | Rotation of the shoulder blade upwards so that the arm can be lifted over the shoulder |
| Back and shoulder muscles | ||||||
| 3 | M. latissimus dorsi | Widest back muscle | Spinous processes ( processus spinosi ) of the lowest 6 thoracic vertebrae, thoracolumbar fascia, iliac crest, lowest 3 or 4 ribs |
Crista tuberculi minoris humeri | Thoracodorsal nerve |
Approaching retroversion / stretching inward rotation |
| 4th | M. deltoideus | Delta-shaped muscle | Clavicle, shoulder roof, spina scapulae |
Humerus deltoid tuberosity | Axillary nerve |
Flexion inward rotation, splaying, extension, outward rotation |
| 5 | M. teres major | large round muscle | lower edge of the shoulder blade ( angulus inferior scapulae ) | Crista tuberculi minoris humeri |
Subscapular nerve Thoracodorsal nerve Axillary nerve |
Approach, extension, inward rotation |
| Rotator cuff (see below) | ||||||
| 6th | M. teres minor | small round muscle | outer edge of the shoulder blade ( Margo lateralis scapulae ) | Tuberculum majus humeri | Axillary nerve | Outward rotation |
| 7th | M. supraspinatus | Upper bone muscle | Supraspinous fossa of the scapula | Tuberculum majus humeri | Suprascapular nerve | Spreading |
| 8th | M. infraspinatus | Lower bone muscle | Infraspinate fossa of the scapula | Tuberculum majus humeri | Suprascapular nerve | Outward rotation |
| 9 | Subscapularis muscle | Subscapular muscle | Front surface of the shoulder blade ( facies costalis scapulae ) | Lesser tuberosity of the humeri | Subscapular nerve |
Inward rotation bring up |
| Front upper arm muscles / elbow flexors | ||||||
| 10 | M. biceps brachii | two-headed upper arm muscle | Long head: Upper part of the joint socket ( labrum supraglenoidale ). Short head: Raven beak process |
Radial tuberosity (on the spoke below the crook of the elbow) | Musculocutaneous nerve |
Flexion in the elbow joint when supinated, supination of the forearm, anteversion in the shoulder joint |
| 11 | M. brachialis | Upper arm muscle | Front surface of the humerus | Anterior surface of ulna, ulnar tuberosity |
Musculocutaneous nerve | Flexion of the forearm |
| 12 | Coracobrachialis muscle | Raven beak muscle | Raven beak process | Inside of the humerus shaft | Musculocutaneous nerve |
Fixation of the humerus head (main function) Anteversion of the humerus |
| Elbow extensor | ||||||
| 13 | M. triceps brachii | three-headed upper arm muscle | Lateral head: humerus near the body. Middle head: humerus far from the body. Long head: infraglenoid tuberosity of the scapulae |
Olecranon (elbow) | Radial nerve | Extension of the elbow joint |
| 14th | M. anconeus | Elbow muscle | Attachment of the lateral humerus knot ( epicondylus lateralis humeri ) | Upper posterior surface of the ulna | Radial nerve | Extension of the elbow joint |
Rotator cuff
In humans, a group of four muscles in the shoulder area is referred to as a rotator cuff (better: muscle-tendon cap), all of which pull from the shoulder blade to the head of the humerus and surround the shoulder joint in the shape of a cap:
- Supraspinatus muscle (upper shoulder bone muscle ),
- Subscapularis muscle (front),
- Infraspinatus muscle (top rear),
- Teres minor muscle (lower back).
These muscles are not visible from the outside, but are covered by the broad and strong deltoid muscle (Musculus deltoideus).
The job of the four muscles is to hold the humerus head in the very flat socket of the shoulder blade. The functional result is an extreme mobility in several bending planes and the axis of rotation. On the other hand, this dynamic fixation causes potential instability, which is why dislocations ( dislocations ) in the shoulder joint are particularly common (see shoulder dislocation ). When a muscle within the rotator cuff is paralyzed, the humerus in the shoulder joint is adjusted. This further increases the risk of dislocation.
When falling on the arm or shoulder, tears often occur, a so-called rotator cuff rupture , and sometimes bone tears at the attachments of the subscapularis and supraspinatus muscles. The cracks mostly affect the sinewy parts of the muscles where they radiate into the bone. These muscle attachments are not supplied with blood and are under tension. The most common cracks are the supraspinatus, followed by the infraspinatus and subscapularis. The teres minor, on the other hand, is almost never affected.
Ducts
Arteries
- The arm artery ( arteria brachialis ) is the continuation of the axillary artery ( arteria axillaris ). On its way down in the nerve-vascular cord, it is accompanied by the median nerve , using the coracobrachialis muscle and the biceps as guide muscles close to the body, while the brachialis muscle far from the body . Therefore, it is ultimately medial (towards the center of the body) of the biceps tendon, so that you can easily feel your pulse with your arm flexed. It has three key exits:
- The deep arm artery ( Arteria profunda brachii ) branches off near the Musculus teres major and, accompanied by the radial nerve , runs through its tunnel to the extensor side. Then it divides into
- the central lateral artery (
- the lateral radial artery ( arteria collateralis radialis ), which runs laterally and represents the actual terminal branch of the deep arm artery. Both arteries run into the arterial network of the elbow joint ( rete articulare cubiti ), as do the other two branches of the arm artery.
- The deep arm artery ( Arteria profunda brachii ) branches off near the Musculus teres major and, accompanied by the radial nerve , runs through its tunnel to the extensor side. Then it divides into
- The superior lateral ulnar artery ( arteria collateralis ulnaris superior ) emerges late from the arm artery and then runs along with the nervus radialis on the extensor side.
- Her little sister, the lower lateral ulnar artery ( arteria collateralis ulnaris inferior ), branches off further away from the arm artery, i.e. just before the elbow. Because of the numerous inflows into the arterial network, the arm artery can easily be tied off as soon as the deep arm artery is branched off.
Veins
There are two types of veins, on the one hand deep veins, which essentially follow the same course as the arteries, and on the other hand superficial veins, which mostly run under the skin with lymphatic vessels and are connected to the deep veins. There are two large veins on the upper arm. They emerge from a network of veins on the back of the hand, rise up the arm and then step down, perforating fascia . These two vein trunks are:
- The basilica vein , which runs in the middle and penetrates about halfway through the basilicus hiatus (together with a cutaneous nerve of the forearm) to merge into one of the two arm veins ( brachial veins ) and
- the cephalic vein , which runs laterally (on the upper arm in the lateral biceps furrow) and plunges into the depths below the collarbone between the deltoid and pectoralis major muscles. It gets into the so-called Mohrenheim pit ( Fossa infraclavicularis ), pierces the Fascia clavipectoralis and finally opens into the Vena subclavian . These two veins are connected to each other.
The following table compares the most important properties of the two venous trunks:
| Surname | Vena basilica | Cephalic vein |
| course | Inside of the arm | Outside of the arm |
| Confluence | The basilic hiatus is the septum between the muscles | Mohrenheimgrube |
| Target (deep vein) | One of the two deep arm veins (Venae brachiales) | Subclavian vein |
annoy
Nerves of the brachial plexus
Some nerves of the arm nerve plexus ( plexus brachialis ) run on the upper arm :
- The muscle-and-cutaneous nerve ( nervus musculocutaneus ) is a crucial descendant of the lateral fasciculus . After a short course in the nerve-vascular cord, it pulls to the coracobrachialis muscle , pierces it and then moves to the side between the biceps brachii muscle and the brachialis muscle ; In the vicinity of the muscles, it releases corresponding muscle branches ( rami musculares ). At the level of the elbow joint, it releases some sensitive branches to the anterior joint capsule ( rami articulares ), but the main part extends to the lateral anterior forearm in order to provide sensitive care in an area close to the body ( nervus cutaneus antebrachii lateralis ). The function of the musculocutaneous nerve can be tested with the help of the biceps tendon reflex: A blow on the biceps tendon with a flexed arm usually triggers a short flexion movement - analogous to the patellar tendon reflex on the leg.
- The radial nerve is the extensor nerve of the arm. It emerges from the posterior fasciculus and enters the nerve-vascular cord. However, it soon leaves this and pulls to the side together with the deep arm artery ( arteria profunda brachii ) in order to enter its canal ( sulcus nervi radialis ) on the posterior humerus after releasing the motor branches for the triceps muscle . Now it winds around the humerus, in this way comes to the side and runs for a certain distance in the lateral bicep groove. Then it steps forward between the brachialis and brachioradialis muscles ( radial tunnel ) so that it comes to rest in the elbow. It splits into a deep and a superficial part, which eventually comes back to the extensor side.
- The median nerve arises from the tributaries of the central and lateral fasciculus (median fork). In the nerve-vascular cord it pulls back on the arm artery ( arteria brachialis ); in doing so, it winds around the artery so that it is no longer on the side of the artery, but in the middle of the artery. It pulls back between the two heads of the pronator teres muscle , goes under the ligamentous plexus on the flexor side ( retinaculum flexorum ) and then branches out to innervate numerous muscles.
- The ulnar nerve ( Nervus ulnaris ) runs relatively straight on the ulnar side of the arm, but alternates twice between the front and back. The nerve stems from the medial fasciculus and initially runs with the arm artery in the nerve-vascular cord, namely in front of the septum between the muscles ( intermuscular septum ). At half the length of the upper arm, together with the upper lateral ulnar artery ( arteria collateralis ulnaris superior ) , it pierces the septum and thus reaches the extensor side. On its way down, it runs through its own canal at the top of the lateral knot; At this point, the nerve is particularly easy to feel and stimulate (musician's bones). In the further course it steps back on the front side and supplies a number of muscles.
- The medial (inner) arm skin nerve ( Nervus cutaneus brachii medialis ) supplies the skin on the upper arm.
- The medial forearm skin nerve ( nervus cutaneus antebrachii medialis ) also emerges from the fasciculus medialis and is located in the nerve-vascular cord in the middle of the arm artery. But soon it leaves the cord and, together with the basilic vein , pierces the upper arm fascia so that it is now on the surface. Finally he arrives at his supply area, the skin of the central forearm close to the body.
- The axillary nerve ( Nervus axillaris ) supplies the Musculus deltoideus and the Musculus teres minor .
Cutaneous nerves
The supply area on the upper arm can only be blurredly separated from the neighboring areas. A distinction is made between four areas: one medial, two lateral and one rear, which are each supplied ( innervated ) by upper arm skin nerves ( Nervi cutanei brachii ) (Fig. 1):
- The medial area, i.e. the area that extends on the inside of the upper arm approximately from the top of the medial epicondyle to the axillary folds, is supplied on the one hand by the central arm skin nerve ( nervus cutaneus brachii medialis ), which emerges from the fasciculus medialis . On the other hand, the nerves that run from the area between the ribs to the upper arm ( Nervi intercostobrachiales ) radiate into this area.
- The lateral area is supplied close to the body by the upper lateral arm skin nerve ( Nervus cutaneus brachii lateralis superior ). It is the only sensitive branch of the axillary nerve ( axillary nerve ).
- The lateral area distant from the body is supplied by the lower lateral arm skin nerve ( Nervus cutaneus brachii lateralis inferior ), which arises from the radial nerve ( N. radialis ).
- The rear area is ultimately quite narrow, because the medial and lateral supply areas extend far to the rear. This is the area of the posterior arm skin nerve ( Nervus cutaneus brachii posterior ), which also originates from the radial nerve .
Bingo wings
This term from English ( bingo , the parlor game, and wings for wings ) describes an area of skin hanging down from the underside of the upper arm (triceps), which mostly occurs in older and overweight people due to fat build-up in the triceps area, but also with significant weight loss. The term, which was coined in the 1990s and was mostly used in a derogatory and misogynistic way, was made popular by the English cabaret artist Leigh Francis in the show Bo 'Selecta! ( Channel 4 ). He refers to the cliché of older women who raise their arms when playing bingo and show the soft fabric of their upper arms when they win. Bingo Wings found its way into English-language lexicons and is increasingly found in the German-speaking area.
literature
- Rolf Bertolini , Gerald Leutert : Systematic human anatomy. People and health, Berlin 1979 and Fischer, 1979, Urban & Fischer, Stuttgart 2002, ISBN 3-86126-077-8
- W. Platzer et al. a .: Pocket Atlas of Anatomy - 1. Musculoskeletal system . Thieme publishing house
Web links
Individual evidence
- ↑ see e.g. B. The definition of Bingo Wings in the Oxford Dictionaries