상완이두근(biceps brachii)과 상완근(brachialis)

[문형철]

1. 상완이두근은 장두, 단두 두섬유가 있음.

2. 상완이두근 장두는 glenoid의 관절순에 부착하여 SLAP 질병을 흔히 유발함.

3. 상완이두근 건염의 95%는 약간의 SLAP을 동반함. 

4. 팔꿈치 쪽에서는 aponeurosis of biceps brachii , biceps brachii tendon으로 이어짐. 

5. 상완이두근은 근피신경지배(C6,7)

6. 그립을 잡을때 엘보를 완전 supinate하면 상완이두근 단두운동

상완이두근 스트레칭

panic bird...

When the humerus is in motion, the tendon of the long head is held firmly in place in the intertubercular groove by the greater and lesser tubercles and the overlying transverse humeral ligament. During the motion from external to internal rotation, the tendon is forced medially against the lesser tubercle and superiorly against the transverse ligament. ^[2] The tendon of the short head runs adjacent to the tendon of the coracobrachialis and likewise attaches to the coracoid process.

Both heads join on the middle of the humerus, usually near the insertion of the deltoid, to form a common muscle belly. Distally, biceps ends in two tendons: the stronger attaches to (inserts into) the radial tuberosity on the radius, while the other, the bicipital aponeurosis, radiates into the ulnar part of the antebrachial fascia. ^[3]

The tendon that attaches to the radial tuberosity is partially or completely surrounded by a bursa; the bicipitoradial bursa, which ensures frictionless motion between the biceps tendon and the proximal radius during pronation and supination of the forearm.^[4]

Two additional muscles lie underneath the biceps brachii. These are the coracobrachialis muscle, which like the biceps attaches to the coracoid process of the scapula, and the brachialis muscle which connects to the ulna and along the mid-shaft of the humerus. Besides those, the brachioradialis muscle is adjacent to the biceps and also inserts on the radius bone, though more distally.

Variation[edit]

Traditionally described as a two-headed muscle, biceps brachii is one of the most variable muscles of the human body and has a third head arising from the humerus in 10% of cases (normal variation) — most commonly originating near the insertion of the coracobrachialis and joining the short head — but four, five, and even seven supernumerary heads have been reported in rare cases. ^[5] The distal biceps tendons are completely separated in 40% and bifurcated in 25% of cases. ^[6]

Innervation[edit]

See also: Biceps reflex

Biceps brachii is innervated by the musculocutaneous nerve together with coracobrachialis and brachialis; like the latter, from fibers of the fifth and sixth cervical nerves. ^[7]

상완이두근 기능

The biceps is tri-articulate, meaning that it works across three joints.^[8] The most important of these functions is to supinate the forearm and flex the elbow.

These joints and the associated actions are listed as follows in order of importance:^[9]

• Proximal radioulnar joint (upper forearm) – Contrary to popular belief, the biceps brachii is not the most powerful flexor of the forearm, a role which actually belongs to the deeper brachialis muscle. The biceps brachii functions primarily as a powerful supinator of the forearm (turns the palm upwards). This action, which is aided by the supinator muscle, requires the elbow to be at least partially flexed. If the elbow, or humeroulnar joint, is fully extended, supination is then primarily carried out by the supinator muscle.
• Humeroulnar joint (elbow) – The biceps brachii also functions as an important flexor of the forearm, particularly when the forearm is supinated. Functionally, this action is performed when lifting an object, such as a bag of groceries or when performing a biceps curl. When the forearm is inpronation (the palm faces the ground), the brachialis, brachioradialis, and supinator function to flex the forearm, with minimal contribution from the biceps brachii.
• Glenohumeral joint (shoulder) – Several weaker functions occur at the glenohumeral, or shoulder, joint. The biceps brachii weakly assists in forward flexion of the shoulder joint (bringing the arm forward and upwards). It may also contribute to abduction (bringing the arm out to the side) when the arm is externally (or laterally) rotated. The short head of the biceps brachii also assists with horizontal adduction (bringing the arm across the body) when the arm is internally (or medially) rotated. Finally, the short head of the biceps brachii, due to its attachment to the scapula (or shoulder blade), assists with stabilization of the shoulder joint when a heavy weight is carried in the arm.

Training[edit]

The biceps can be strengthened using weight and resistance training. Examples of well known biceps exercises are the chin-up and biceps curl. 

1) chin-up

2) biceps curl

To isolate the biceps brachii in elbow flexion, place the shoulder in hyperextension. In training the biceps brachii, it is important to distinguish between the long head and the short head of the biceps. The long head is the outer portion of the muscle. The short head is the inner portion of the muscle. If you look at the additional images below, you will see a picture that highlights each of the bicep heads for you.

- 팔꿈치 굴곡을 이용한 상완이두근 운동시에 isoloation하려면 어깨를 신전시키면 됨

- 상완이두근 운동은 장두와 단두운동을 구분해야

- 그립을 잡을때 완전 supinate하면 단두운동!!

There is much debate over the best bicep workouts for targeting each of these heads. The first theory for targeting is based on the proximity of the arms in relation to the body. It is said that when the elbows are pulled back behind the body, this targets the long head more. To target the short head, the elbows should be in front of the body.

The second theory uses grip placement and angle as the primary factor in targeting each head. For instance, to target the long head when using dumbbells or cables, the grip should be semi-supinated (hammer) grip where the palms face each other. If using a barbell (EZ grip or straight), the grip should be inside of shoulder width. To target the short head when using dumbbells or cables, grip should be supinated, where the palms are facing up completely. If using a barbell (EZ grip or straight), grip should be outside of shoulder width.^[10]

Clinical significance[edit]

The proximal tendons of the biceps brachii are commonly involved in pathological processes and are a frequent cause of anterior shoulder pain.^[11] Disorders of the distal biceps brachii tendon typically result from partial and complete tears of the muscle. Partial tears are usually characterized by enlargement and abnormal contour of the tendon.^[12] Complete tears generate a soft-tissue mass in the anterior aspect of the arm, the so called Popeye sign, which paradoxically leads to a decreased strength during flexion and supination of the forearm.^[13] Tears of the biceps brachii occur in athletic activities and corrective surgery repairs biceps brachii tendon tears. Proximal ruptures of the long head of the biceps tendon can be surgically repaired by two different techniques. Biceps tenodesis is resurfacing the tendon by screw fixation on the humerus and biceps tenotomy is trimming the long head of the biceps tendon promoting the muscle origination from the coracoid process.Preexisting degeneration in the tendon can cause partial tears called lesions and are rarely associated with a traumatic event. The most common symptom of a biceps tear is pain. It will be the most severe in the muscle, but may stretch to the shoulders and elbows as well. Treatment of a biceps tear depends on the severity of the injury. In most cases, the muscle will heal over time with no corrective surgery. Applying cold pressure and using anti-inflammatory medications will ease pain and reduce swelling. More severe injuries require surgery and post-op physical therapy to regain strength and functionality in the muscle. Corrective surgeries of this nature are typically reserved for elite athletes who rely on a complete recovery.^[14]

상완이두근 Trp 탐구

상완근 brachialis

- 상완근은 척골에 부착하기 때문에 팔꿈치의 회내, 회외에 전혀 관여하지 못함. 

The brachialis (brachialis anticus) is a muscle in the upper arm that flexes the elbow joint. It lies deeper than the biceps brachii, and is a synergist that assists thebiceps brachii in flexing at the elbow. It makes up part of the floor of the region known as the cubital fossa.

Structure[edit]

The brachialis originates from the lower half of the front of the humerus, near the insertion of the deltoid muscle, which it embraces by two angular processes. Its origin extends below to within 2.5 cm of the margin of the articular surface of the humerus at the elbow joint. It also arises from the intermuscular septa of the arm, but more extensively from the medial than the lateral; it is separated from the lateral below by the brachioradialis and extensor carpi radialis longus muscles.

Its fibers converge to a thick tendon, which is inserted into the tuberosity of the ulna and the rough depression on the anterior surface of the coronoid process of the ulna.

Variation[edit]

The muscle is occasionally doubled; additional nip to the supinator, pronator teres, biceps brachii, lacertus fibrosus, or radius are more rarely found.

Innervation[edit]

The brachialis muscle is innervated by the musculocutaneous nerve, which runs on its superficial surface, between it and the biceps brachii. Part of it is also innervated by the radial nerve (proprioceptive branch) which allows it to be split during certain approaches to the arm. The divide between the two innervations is at the insertion of the deltoid.

Actions[edit]

Unlike the biceps, the brachialis does not insert on the radius, and therefore cannot participate in pronation and supination of the forearm. It flexes the elbow joint.

History[edit]

Etymology[edit]

The brachialis muscle ^[1] and brachial muscle ^[2] can be considered as the anglicized variant of the Latin expression‎ musculus bracchialis.^[3] In classical Latin bracchialis means of or belonging to the arm,^[4] and is derived from classical Latin bracchium,"arm".^[4] The spelling brachium is less correct,^[4] and bracchialis is preferred above brachialis.^[4] The expression‎ musculus brachialis is however used in the current official anatomic nomenclature Terminologia Anatomica.^[5]

Although bracchium in general can refer to the arm,^[4] more specifically it can refer to the forearm.^[6][7] Latin encyclopedist Aulus Cornelius Celsus defined the bracchium as: "constat ex ossibus duobos, quae sunt radius et cubitus",^[6] (consists of two bones, that are the radius and the ulna) with cubitus in the nomenclature of Celsus referring to the ulna.^[6] Confusingly the brachialis muscle actually more resides at the upperarm than at the forearm.

상완근의 Trp 탐구

에반스의 상완 이두근 장두 isolated stretching

에반스의 상완 이두근 단두 isolated stretching

상완근 스트레칭