The Arm

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The Arm
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• The arm participates in only two types of
  movements
• Flexion/extension at the elbow joint
• Pronation/supination at the radioulnar and
  radiohumeral joint

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Arm Muscles

• 3 Anterior compartment muscles
• 1. Biceps brachii
• a. Long head
• b. Short head All by Musculocutaneous
• 2. Brachialis
• 3. Coracobrachialis

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Brachial Musculature

• 2 Posterior compartment muscles
• 1. Triceps
• a. Long head
• b. Lateral head All by Radial nerve
• c. Medial head
• 2. Anconeus

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Biceps Brachii

• O long head the tendon of the long head passes
  through the intertubercular sulcus, formed into a
  tunnel by the transverse humeral ligament, to the
  supraglenoid tubercle
• O- short head the coracoid process of the
  scapula
• I - Radial tubercle, bicipital aponeurosis and
  antebrachial fascia
• Action-Flexes and supinates the forearm, the
  strongest forearm supinator with the forearm at
  90 , with forearm at 90 and supinated its the
  strongest forearm flexor. The biceps has no
  humeral attachments, it is a weak arm flexor.
• Innervation Musculocutaneous nerve

• Table 6.6 p788-89

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Brachialis

• The workhorse of the anterior compartment,
  located deep to the biceps, a pure flexor
• O- Distal half anterior humerus
• I Inserts into the tuberosity and anterior
  surface of the coronoid process of the ulna
• Action- a pure forearm flexor,the most powerful
  forearm flexor at the elbow
• Innervation ?_______________ also receives a
  minor branch form the radial nerve (C7).

• Table 6.6 p788-89

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Coracobrachialis

• A landmark for other structures, median nerve and
  brachial artery run posterio-medial to it, the
  nutrient artery of the humerus enters the bone at
  its distal end, pierced by the musculocutaneous
  nerve.
• O- Coracoid process (with biceps forms the
  conjoined tendon)
• I middle 1/3rd anterior humerus
• Action flexes and adducts arm
• Innervation_________________

• Table 6.6 p788-89

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Triceps

• O Long head infraglenoid tubercle of the
  scapula
• - Lateral head posterior humerus superior
  to the radial groove
• - Medial head posterior humerus inferior
  to the radial groove
• I proximal olecranon deep fascia of the
  forearm (there is a prominent subolecranon bursa
• Action all are involved in extension of the
  forearm
• Long head crosses glenohumeral junction,
  weak arm extension and adduction.
• Lateral head the strongest, most often
  recruited to resist flexion
• Medial head major forearm extender
• Innervation all innervated by the radial nerve,
  pre-radial groove lateral long heads, post
  groove the medial head.

• Table 6.6 p788-89

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Anconeus

• O- Lateral epicondyle of humerus
• I Lateral olecranon posterior surface of the
  ulna
• Action helps extend the forearm, tenses the
  elbow joint capsule to prevent entrapment, and
  abducts the ulna during pronation.
• Innervation by ____________________

• Table 6.6 p788-89

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Cubital fossa A triangle with a roof and a floor

• Boundaries
• Superior a line from the medial to the lateral
  epicondyle
• Medial - common flexor forearm tendon and
  pronator teres
• Lateral - extensor tendon from the lateral
  epicondyle, brachioradialis.
• Floor brachialis supinator
• Roof skin, median cubital vein, fat, fascia
  bicipital aponeurosis.
• Contents
• Terminal brachial artery with the radial ulnar
  branches.
• Veins
• Biceps tendon
• Median nerve

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• Fig 6.33 p 790

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Spaces of the posterior arm

• Quadrangular space
• Borders lateral long heads triceps, teres
  minor teres major tendons
• Contents axillary nerve posterior circumflex
  artery
• Triangular space
• Borders teres minor, teres major long head
  triceps
• Contents circumflex scapular artery
• Triangular interval
• Borders inferior border teres major, long
  lateral heads triceps
• Contents radial nerve and profunda brachii
  artery

• Fig 6.34 p 791

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Brachial artery

• Brachial artery is a continuation of the
  axillary artery beginning at the teres major to
  the cubital fossa, opposite the neck of the
  radius it splits into the radial ulnar
  arteries.
• It runs in the bicipital groove, anterior to the
  triceps and brachialis, medial to the humerus.
  Anterior to the medial supracondylar ridge (with
  the median nerve) it enters the cubital fossa
  posterior to the nerve

• Fig 6.35 p 792

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• Brachial artery branches
• A number of muscular branches throughout its
  course.
• Nutrient artery to the humerus ( at
  coracobrachialis)
• Profunda brachii, with the radial nerve in the
  spiral groove, gives off anterior and posterior
  collateral branches at the lateral epicondyle to
  anastomose with the middle and radial collateral
  branches.
• Superior ulnar collateral anastomosis with the
  posterior ulnar recurrent artery
• Inferior ulnar collateral anastomosis with the
  anterior ulnar collateral.

• Fig 6.35 p 792

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Brachial artery

• The peri-elbow collateral circulation allows flow
  to continue distally when the forearm is fully
  flexed with resulting nearocclusion of the
  brachial artery. It is acceptable to ligate the
  brachial artery distal to the profunda branch
  because of this collateral system.

• Fig 6.35 p 792

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• Veins
• Superficial Cephalic Basilica
• Deep Brachial forms at the elbow by the
  confluence of the radial and ulnar veins, joined
  by the basilic to form the axillary vein.

• Fig 6.13 p 749

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• Fig 6.36 p 792

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Humerus Fractures

• Surgical neck fractures
• What structures are at risk?

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Humerus Fractures

• If the fracture is complex in nature, open
  reduction with internal fixation may be
  necessary. This can be accomplished with a plate
  and screws or with an intramedullary (IM) rod or
  nail. Both methods of internal fixation are very
  invasive and have potential complications

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• . The most common complication of a humerus
  fracture is impingement of the radial nerve
• If the humerus is fractured distally or midshaft,
  the radial nerve can become entrapped in the
  fracture site or a fracture fragment. This
  graphic shows the radial nerve becoming entrapped
  in the fracture more distally. The nerve can also
  become entrapped when the physician performs a
  closed reduction of a displaced fracture.
• It is estimated that up 18 of all humerus
  fractures involve damage to the radial nerve..
• Radial nerve palsy results in the inability to
  extend the wrist and fingers as seen in the
  picture.
• Recovery rates are relative to the type of
  fracture and amount of nerve impingement. In 75
  - 90 of the patients treated with a closed
  reduction, full recovery will occur in 3 to 4
  months. This depends upon the amount of nerve
  damage, presence of scar tissue and swelling.
  Nerve will heal at the rate of approximately 1 mm
  per month.