Brachial Intermuscular Septa

Medial Intermuscular Septum- extends from the lesser tubercule to supracondylar ridge. Pierced by the ulnar nerve, superior ulnar collateral artery

Lateral Intermuscular Septum- extends from the greater tubercule to the medial epicondyle. Pierced by the radial nerve and profunda brachii artery

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V-Shaped interval bounded by the brachioradialis and pronator teres, superiorly by the an imaginary horizontal line connecting the epicondyles of the humerus with a floor formed by the brachialis and supinator muscles.

Contains(lateral to medial) radial nerve, biceps tendon, brachial artery and median nerve

Ron Beats Bad Man

the biceps is the primary (most powerful) supinator of the forearm

The biceps barely operates as a flexor when the forearm is pronated

transverse humeral ligament, passes from the lesser to the greater tubercle of the humerus and converts the intertubercular groove into a canal 

Distally, the major attachment of the biceps is to the radial tuberosity via the biceps tendon

bicipital aponeurosis, runs from the biceps tendon across the cubital fossa and merges with the antebrachial (deep) fascia covering the flexor muscles in the medial side of the forearm.

A positive response confirms the integrity of the musculocutaneous nerve and the C5 and C6 spinal cord segments

Excessive, diminished, or prolonged (hung) responses may indicate central or peripheral nervous system disease or metabolic disorders (e.g., thyroid disease).

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The tendon of the long head of the biceps is enclosed by a synovial sheath and moves back and forth in the inter-tubercular groove of the humerus

Inflammation of the tendon (biceps tendinitis), usually the result of repetitive microtrauma, is common in sports involving throwing (e.g., baseball and cricket) and use of a racquet (e.g., tennis).

A tight, narrow, and/or rough intertubercular groove may irritate and inflame the tendon, producing tenderness and crepitus

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Rupture of the tendon usually results from wear and tear of an inflamed tendon as it moves back and forth in the intertubercular groove of the humerus.

Typically, the tendon is torn from its attachment to the supraglenoid tubercle of the scapula.

he detached muscle belly forms a ball near the center of the distal part of the anterior aspect of the arm (Popeye deformity)

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Flexes forearm in all positions

Workhouse of forearm flexors

It flexes the forearm in all positions, not being affected by pronation and supination

The brachialis always contracts when the elbow is flexed and is primarily responsible for sustaining the flexed position. 

eccentric contraction (you use it to pick up and put down a teacup carefully, for example).

 Main Action

Helps flex and adduct arm; resists dislocation of shoulder

landmark for locating the musculocutaneous nerve pierces it

The coracobrachialis helps flex and adduct the arm and stabilize the glenohumeral joint.

The median nerve and/or the brachial artery may run deep to the coracobrachialis and be compressed by it.

Triceps brachii

Main Action

Proximal end of olecranon of ulna and fascia of forearm

Radial nerve (C6,C7, C8)

Chief extensor of forearm; long head resists dislocation of humerus; especially important during abduction

the triceps has three heads: long, lateral, and medial

medial head is the workhorse of forearm extension

Anconeus

Main Action

Radial nerve (C7, C8, T1)

Assists triceps in extending forearm; stabilizes elbow joint; may abduct ulna during pronation

The best place to compress the brachial artery to control hemorrhage is medial to the humerus near the middle of the arm 

Because the arterial anastomoses around the elbow provide a functionally and surgically important collateral circulation,

the brachial artery may be clamped distal to the origin of the deep artery of the arm without producing tissue damage

Muscles and nerves can tolerate up to 6 hours of ischemia

 after this, fibrous scar tissue replaces necrotic tissue and causes the involved muscles to shorten permanently, producing a flexion deformity

Contraction of the fingers and sometimes the wrist results in loss of hand power as a result of irreversible necrosis of the forearm flexor muscles.

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A midhumeral fracture may injure the radial nerve in the radial groove in the humeral shaft.

When this nerve is damaged, the fracture is not likely to paralyze the triceps because of the high origin of the nerves to two of its three heads.

A fracture of the distal part of the humerus, near the supraepicondylar ridges

 The Median Nerve is vulnerable to damage in the supracondylar area

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The medial epicondyle fragment is usually displaced distally

The patient usually presents with a recent history of a significant fall on an outstretched hand or directly on the apex of the flexed elbow.

Distal neurovascular changes may occur, especially in the ulnar nerve distribution. 

Stress Test: check  ulnar collateral ligament 

The medial epicondyle is a prominent palpable process that projects medially from the trochlea and is the point of origin of the pronator teres and common flexor tendon, which includes the flexor carpi radialis, palmaris longus, flexor carpi ulnaris, and flexor digitorum superficialis.

The medial condyle of the humerus is the medial column of the distal expansion of the humerus that includes the trochlea, the coronoid fossa, the olecranon fossa, the medial epicondyle, the medial supracondyle ridge, the medial metaphysis, and the groove for the ulnar nerve.

The trochlea is the distal medial articulating end of the humerus, which acts as a pulley for the ulnar trochlear notch to rotate around as the elbow is flexed

The coronoid fossa is the depression on the anterior surface of the medial condyle proximal to the trochlea that accommodates the coronoid process of the ulna.

The capitellum, a rounded ball of bone adjoining the trochlea laterally, is the distal lateral articulating end of the humerus that articulates with the radial head.

The lateral epicondyle is a prominent palpable process that projects laterally from the capitellum and is the point of origin of the common extensor tendon.

The lateral supracondyle ridge is a bony ridge that runs proximally on the lateral humerus from the lateral epicondyle. 

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