Arm & Cubital Fossa Nicole M. Reeves, Ph.D. Department of Anatomy NicoleReeves@RossU.edu Recommended Reading COA : 7th Edition Pages: 731-744, 800-806, 815-817 *Practice questions can be found on Canvas* Learning objectives • • • • • • • • • Describe the osteology of the arm (humerus) and elbow (proximal radius & ulna) and movements permitted at these joints, and identify features associated with these bones Explain the clinical implications of a humeral neck fracture/mid-humeral shaft fracture/distal humerus inter/supracondylar fracture: signs, symptoms, how/why it happens, motor & sensory deficits if any, bone displacement if any Describe ligaments/tendons associated with the elbow joint (humeroradial & humeroulnar joints), and the movements permitted at this type of joint Explain subluxation and dislocation of the radial head (‘nursemaid’s elbow’) Explain a posterior elbow dislocation: signs, symptoms, how/why it happens, motor & sensory deficits if any, bone displacement if any Identify the following muscles of the arm: coracobrachialis, brachialis, biceps brachii (both heads), triceps brachii (all three heads) and name their actions and innervations. Describe the arterial supply and venous drainage of the arm and elbow Trace the pathway of the musculocutaneous, radial, median, and ulnar nerves in the arm and elbow, and understand their close relationship to other structures § Explain the relationship of nerves & major blood vessels to specific aspects of the osteology & muscles: e.g., injury to medial epicondyle of humerus most likely damages ulnar nerve § Understand the clinical implications (i.e., motor & sensory deficits) of radial, ulnar, & median nerve damage Describe the boundaries, contents, & relationships of the cubital fossa 2 Osteology of the upper limb ANTERIOR POSTERIOR ARM (brachial) FOREARM (antebrachial) HAND 3 Osteology of the clavicle SUPERIOR ACROMIAL END STERNAL END ANTERIOR INFERIOR Costoclavicular ligament attachment 4 Review: Osteology of the scapula Suprascapular Superior angle notch Superior border Supraspinous fossa Medial border Coracoid process POSTERIOR Acromion process Glenoid fossa Infraspinous fossa Scapular spine Lateral border Inferior angle 5 Review: Osteology of the scapula Acromion process ANTERIOR Coracoid process Superior angle Glenoid fossa Subscapular fossa Lateral border Inferior angle Suprascapular notch Medial border 6 Review: Osteology of the scapula LATERAL Acromion process Supraspinous fossa Scapular spine Coracoid process Supraglenoid tubercle Glenoid fossa Infraglenoid tubercle Infraspinous fossa POSTERIOR Subscapular fossa ANTERIOR 7 ANTERIOR Osteology of the humerus POSTERIOR HEAD SHAFT (DIAPHYSIS) CAPITULUM TROCHLEA 8 ANTERIOR Greater tuberosity Anatomical neck Lesser tuberosity Surgical neck Intertubercular groove POSTERIOR Radial groove Deltoid tuberosity Lateral supraepicondylar ridge Lateral epicondyle Medial supraepicondylar ridge Medial epicondyle Olecranon fossa Coronoid fossa 9 Clinical: Humerus fractures Surgical neck fracture • common in elderly • Injury to AXILLARY N. & POSTERIOR CIRCUMFLEX HUMERAL A.; (quadrangular space) Humeral shaft fracture (radial groove) • Transverse fracture à proximal fragment pulled laterally (by deltoid) • Spiral fracture à may result in shortening (due to one end overriding the other) • Injury to RADIAL N. in radial groove & DEEP ARTERY OF ARM (Profunda brachii); (triangular interval) Spiral fracture Supracondylar Distal humerus fracture • Intercondylar vs. supracondylar • Injury to MEDIAN N. & BRACHIAL A. Intercondylar 10 ANTERIOR Osteology of the elbow joint: Hinge, gliding, & pivot portions • Humeroulnar joint – hinge • Humeroradial joint – gliding • Proximal radioulnar joint – pivot HUMERUS Capitulum All 3 portions share a common synovial joint capsule, and elbow is generally referred to as a synovial hinge joint. Coronoid fossa Trochlea Radial head Olecranon fossa Olecranon process Coronoid process Ulnar tuberosity Radial tuberosity ULNA RADIUS POSTERIOR 11 ANTERIOR, in tact Elbow joint synovial capsule JOINT CAPSULE Ulnar collateral l. Radial collateral l. Annular l. of radius ANTERIOR, windowed Ulnar collateral l. MEDIAL Posterior Anterior Oblique 12 Movements of the forearm Flexion – Extension Supination - Pronation • Trochlear notch of ulna moves against trochlea of humerus • Head of radius moves against capitulum of humerus • Head of radius swivels inside the annular ligament, against capitulum & radial notch of ulna 13 Clinical: Elbow dislocation Mechanism *Risk of ulnar nerve (most common) & median nerve injuries • Fall onto extended & abducted arm • Hyperextension of elbow • Direct blow to elbow Posterior dislocation • Most common (80-90%) • Radius & ulna dislocated posterior to humerus “Terrible Triad” injury 1. Elbow dislocation 2. Radial head fracture 3. Coronoid process fracture 14 Clinical: “Nursemaid’s elbow” – Subluxation & dislocation of radius • Typically in children 1-4 years old • Common in the left limb • Tenderness due to pinched annular ligament • Radial head pinches annular ligament against capitulum 2 1. Subluxation 2. Dislocation 1 15 ANTERIOR Muscles of the arm POSTERIOR 16 Arm cross-section & fascial compartments Brachial fascia: ANTERIOR COMPARTMENT Mostly flexors Musculocutaneous nerve Brachial artery R arm, midshaft SUPERIOR Brachial fascia: POSTERIOR COMPARTMENT Mostly extensors Radial nerve Deep artery of the arm Lateral intermuscular septum Compartment syndrome: increased pressure in the muscle compartment • Can lead to muscle, nerve damage and ischemia Medial intermuscular septum 17 ANTERIOR Muscles of the arm POSTERIOR BICEPS BRACHII long head short head CORACOBRACHIALIS TRICEPS BRACHII long head lateral head BRACHIALIS ANCONEUS 18 Anterior compartment: Biceps brachii ANTERIOR ACTIONS: • Supinates forearm • Flexes supine forearm • Helps hold humeral head in glenoid fossa INNERVATION: Musculocutaneous nerve ORIGIN: Short head – coracoid process Long head – supraglenoid tubercle Long head Short head BICEPS BRACHII BRACHIALIS INSERTION: Radial tuberosity & forearm fascia via bicipital aponeurosis 19 Clinical: Rupture of tendon of long head of biceps brachii • Location of injury: “wear & tear” over intertubercular sulcus • Common in males 40-60 Symptoms: • Audible snap/pop • Bulge in center of distal anterior arm (“Popeye deformity”) • Pain and tenderness at shoulder 20 Anterior compartment: coracobrachialis ACTIONS: ANTERIOR CORACOBRACHIALIS • Adduct humerus • Flex arm INNERVATION: Musculocutaneous nerve ORIGIN: Coracoid process INSERTION: Middle 1/3 of medial humerus 21 Anterior compartment: Brachialis ANTERIOR ACTIONS: • Flexes forearm in all positions INNERVATION: Musculocutaneous nerve BRACHIALIS ORIGIN: Distal ½ of anterior surface of humerus INSERTION: Coronoid process of ulna 22 Anterior compartment: Musculocutaneous nerve (C5-C7) PATHWAY: 1. Pierces coracobrachialis muscle 2. Travels distally between biceps brachii & brachialis 3. Emerges lateral to biceps as the lateral cutaneous nerve of the forearm Musculocutaneous nerve Lateral antebrachial cutaneous nerve DAMAGE TO MUSCULOCUTANEOUS NERVE: • Weak flexion at glenohumeral joint • Weak flexion & supination at elbow joint • Loss of sensation in the lateral aspect of the forearm 23 Posterior compartment: Triceps brachii POSTERIOR ACTIONS: • Extends forearm • Long head: resists inferior dislocation of humerus during adduction • Long head: adduct & extends arm INNERVATION: Radial nerve ORIGIN: Long head Lateral head TRICEPS BRACHII Long head – infraglenoid tubercle Lateral head – posterior surface of humerus, superior to radial groove Medial head – posterior surface of humerus, inferior to radial groove INSERTION: Olecranon process ANCONEUS 24 Posterior compartment: Triceps brachii POSTERIOR ACTIONS: • Extends forearm • Long head: resists inferior dislocation of humerus during adduction • Long head: adduct & extends arm INNERVATION: Radial nerve ORIGIN: Lateral head (cut) Long head Medial head TRICEPS BRACHII Long head – infraglenoid tubercle Lateral head – posterior surface of humerus, superior to radial groove Medial head – posterior surface of humerus, inferior to radial groove INSERTION: ANCONEUS Olecranon process 25 Clinical: Deep tendon reflexes Biceps brachii reflex (C5-C6): • tests the integrity of musculocutaneous nerve Triceps brachii reflex (C7-C8): • tests the integrity of the radial nerve Diminished reflex = lesion at lower motor neuron affecting peripheral nerves Brisk reflex = lesion at upper motor neuron which is in the central nervous system *You will learn more details about this next semester! 26 Posterior compartment: Anconeus POSTERIOR ACTIONS: • Assists in forearm extension • Stabilizes elbow INNERVATION: Radial nerve ORIGIN: TRICEPS BRACHII Lateral epicondyle of humerus INSERTION: Lateral surface of olecranon process & superior part of posterior ulna ANCONEUS 27 Posterior compartment: Radial nerve in the arm Triangular interval PATHWAY: 1. Enters the arm posterior to the brachial artery, medial to the humerus, & anterior to the long head of the triceps POSTERIOR Radial nerve 2. Descends inferolaterally with the deep artery of the arm in the radial groove, between the lateral & medial heads of the triceps 3. When it is lateral to the humerus, it pierces the lateral intermuscular septum as it moves into the forearm anterior to the lateral epicondyle, between the brachialis & brachioradialis Intermuscular septum 28 Clinical: Injury to radial nerve in the arm Injury superior to the origin of triceps brachii branches: • Paralysis of ALL muscles supplied by the radial nerve (i.e. triceps, brachioradialis, supinator, & extensors of the wrist & fingers) • Sensory loss (see radial nerve cutaneous innervation in Brachial Plexus lecture) Injury in the radial groove: • Paralysis of the medial head of triceps & all posterior muscles of forearm distal to the site of nerve lesion • Lateral & long heads of triceps not affected, meaning elbow extension is weakened but not lost • Sensory loss (see radial nerve cutaneous innervation in Brachial Plexus lecture) Characteristic clinical sign of radial nerve injury is “wrist-drop” – cannot extend wrist! 29 Median, Ulnar, & Radial nerves in the arm, forearm, & hand *Note the proximity of the Ulnar nerve & the medial epicondyle *Note the proximity of the Radial nerve & the lateral epicondyle You will learn more details about the Median and Ulnar nerves in the Forearm & Hand lecture! 30 Arteries of the arm Brachial artery • continuation of the axillary a. once it passes teres major • at first, medial to humerus • moves inferolaterally, overlying brachialis, accompanying the median nerve • terminates in cubital fossa into radial & ulnar arteries Humeral nutrient artery • enters into the nutrient canal of the humerus Radial artery • lateral terminal division of the brachial a. TERES MAJOR Deep artery of the arm • first & largest branch from brachial artery • passes posterior to the humerus with the radial n. in the radial groove Ulnar artery • medial terminal division of the brachial a. Common interosseous artery • gives off the interosseous recurrent a., part of the 31 elbow anastomosis Arm arterial flow chart through the cubital fossa Axillary Radial collateral Deep artery of arm (profunda Middle collateral brachii) Superior ulnar collateral After inferior border of teres major Brachial Inferior ulnar collateral Anterior ulnar recurrent Radial Radial recurrent Ulnar Posterior ulnar recurrent Common interosseous Anterior interosseous Posterior interosseous Recurrent interosseous 32 Clinical: Assessing blood pressure & brachial artery pulse Blood pressure: • cuff placed around the mid-arm, compresses brachial artery against humeral shaft Brachial artery pulse • medial to biceps brachii tendon (in cubital fossa) – TAN (lateral to medial) 33 Clinical: Ischemia of elbow & forearm Muscles & nerves can tolerate up to 6 hours of ischemia • after this point, fibrous scar tissue replaces necrotic tissue & causes the involved muscles to shorten permanently, producing a flexion deformity, ischemic compartment syndrome or “Volkmann contracture” Mechanism: • sudden brachial artery occlusion or laceration • collateral pathways only help in gradual & partial occlusion 34 Superficial veins of the arm The SUPERFICIAL veins are shown here. The DEEP veins lie internal to deep fascia, and accompany arteries in pairs. Named for the major arteries of the arm. Basilic vein Cephalic vein • ascends from the anteromedial forearm into the arm • at approximately the middle of the arm, it pierces the brachial fascia to run with the brachial artery • ascends from the anterolateral forearm into the arm, communicating with the median cubital vein, moving up the arm through the deltopectoral groove, before diving deep to the clavicle to join the axillary vein Median cubital vein • passes obliquely in the cubital fossa, connecting cephalic 35 & basilic veins Superficial cubital fossa Contents overlying the cubital fossa – “roof” • Median cubital vein, lateral cutaneous nerve of forearm, medial cutaneous nerve of forearm Boundaries • Brachioradialis muscle • Pronator teres muscle • Medial & lateral epicondyles of humerus 36 Deep cubital fossa Contents – what’s in the deep cubital fossa • (From lateral to medial) Tendon of Biceps brachii muscle, Brachial artery, MEDIAN nerve • TAN (lateral to medial) à tendon (biceps brachii), artery (brachial artery), nerve (median nerve) Remember TAN à tendon (biceps brachii), Brachial artery, Median nerve (lateral to medial) 37 Clinical: Venipuncture Target: median cubital vein Bicipital aponeurosis protects brachial artery & median nerve, which are deep to the aponeurosis 38 Additional slides: (This slide is included to help clarify presented concepts. You are not responsible for the collateral pathways.) 39 Elbow anastomoses COLLATERAL ARTERIES Deep artery of the arm • branch superior to the elbow • run inferiorly Brachial a. RECURRENT ARTERIES • branch inferior to the elbow • run superiorly Double arrows indicate blood flow either way if necessary Superior ulnar collateral a. Middle collateral a. Radial collateral a. Inferior ulnar collateral a. Radial recurrent a. Anterior ulnar recurrent a. Interosseous recurrent a. Posterior ulnar recurrent a. Ulnar a. Radial a. 40
