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Biceps Brachii
- Proximal Attachment: Short head: tip of coracoid process of scapula; Long head: supraglenoid tubercle of scapula and superior glenoid labrum
- Distal Attachment: Radial tuberosity and fascia and skin of forearm via bicipital aponeurosis
- Innervation: Musculocutaneous n. (C5–C7)
- Main Actions: supinates forearm and, when it is supinated, flexes forearm/elbow; short head resists dislocation of shoulder; long head stabilises GH joint
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Coracobrachialis
- Proximal Attachment: Tip of coracoid process of scapula
- Distal Attachment: middle third of medial surface of humerus
- Innervation: Musculocutaneous n. (C5–C7) (pierces)
- Main Actions: helps flex and ADduct humerus; resists dislocation of shoulder
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Brachialis
- Proximal Attachment: Distal half of anterior surface of humerus
- Distal Attachment: Coronoid process and tuberosity of ulna
- Innervation: Musculocutaneous n. (C5–C6)
- Main Actions: Flexes forearm in all positions; uses trochlea as a pulley
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Triceps
- Proximal Attachment: Long head: infraglenoid tubercle of scapula; medial head: posterior surface of humerus inferior to radial groove; lateral head: posterior surface of humerus superior to radial groove
- Distal Attachment: Proximal end of olecranon of ulna and fascia of forearm
- Innervation: Radial n. (C6–C8)
- Main Actions: Chief extensor of forearm; long head extends and resists dislocation of shoulder; especially important during adduction
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Anconeus
- Proximal Attachment: Lateral epicondyle of humerus
- Distal Attachment: Lateral surface of olecranon and superior part of posterior surface of ulna
- Innervation: Radial n. (C7–T1)
- Main Actions: Assists triceps in extending forearm at terminal extension; stabilises elbow joint; may ABduct ulna during pronation (valgus stress)
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Contents of Anterior Compartment of Brachium
- Biceps Brachii
- Brachialis
- Coracobrachialis
- Musculocutaneous n. (innervates)
- Brachial a.
- Median n. (medial, does not innervate)
- Ulnar n. (medial, does not innervate)
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Contents of Posterior Compartment of Brachium
- Triceps Brachii
- Radial n. (Innervates)
- Radial a.
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Bicipital myotactic reflex
hit biceps tendon to test C6 spinal root integrity
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Triceps Tendon Myotactic Reflex
hit triceps tendon to test C7 spinal root integrity
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Musculocutaneous n.
- Comes off lateral cord of brachial plexus
- Pierces coracobrachialis
- Goes between biceps and brachialis
- Emerges lateral to biceps brachii and innervates skin of lateral forearm
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Radial n.
- Branch of posterior cord of brachial plexus
- Goes through triangular interval
- Runs in radial groove of humerus deep to triceps lateral head and long bead; superior to medial
- Divides in cupital fossa into superficial and deep
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Cubital Fossa
- Triangular in shape
- Borders: line between epicondyles; pronator teres (inferior medial); brachioradialis (inferior lateral)
- Contents (lateral to medial): biceps tendon; brachial artery (splits in fossa); median nerve
- Floor: brachialis
- Deep muscle: supinator (wraps around neck, tuberosity, and shaft of radius)
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Elbow Joints
- Humerus and Ulna (flexion and extension) — modified hinge: trochlea and trochlear notch
- Humerus and Radius (flexion extension): capitulum and radial head
- Radius and Ulna (pronation supination): radial head and radial notch of ulna
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Elbow Joint Stability
- Joint Capsule (weak anteriorly and posteriorly)
- MCL/UCL (ulnar collateral ligament)
- LCL/RCL (radial collateral)
- Bone articulations
- Muscles crossing the joint
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Ulnar Collateral Ligament (UCL)
- a.k.a. MCL
- Anterior Bundle: medial epicondyle of humerus to coronoid process of ulna; taught especially in extension; strongest band
- Posterior Bundle: medial epicondyle of humerus to olecranon process of ulna; taught especially in flexion
- Transverse Bundle: coronoid process of ulna to olecranon process of ulna; helps deepen socket
- Prevent valgus forces
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Radial Collateral Ligament (RCL)
- a.k.a. LCL
- RCL part: lateral epicondyle to annular ligament
- LUCL part: lateral epicondyle to supinator crest of ulna
- Prevents: radial head subluxation; varus stress
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Annular Ligament
- Radial notch to radial notch on ulna
- Prevents: separation of radial head and ulna
- Lined with synovial membrane
- Allows rotation of radius
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Oblique Cord
- Lateral ulnar tuberosity to just below radial tuberosity
- Prevents: inferior translation of radius
- Stabilises proximal radioulnar joint during movement
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Bursas of Elbow Joint
- 2 clnically important
- Olecranon bursae: decreases friction between triceps tendon, olecranon, and skin
- Bicipitoradial bursa: between biceps tendon and radial tuberosity
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Brachial Artery
- Starts distal to teres major
- Runs medial to biceps brachii
- Divides into Radial a. and Ulnar a. in cubital fossa
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Arterial Anastomoses
- Superior ulnar collateral <--> Posterior ulnar recurrent
- Inferior ulnar collateral <--> Anterior ulnar recurrent
- Radial recurrent <--> radial collateral
- Interosseous recurrent <--> Middle collateral
- Collaterals go with recurrents
- Consonants together
- Vowels together
- Radials together
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