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Upper Limb, part I Shoulder, Arm, and Axilla. Objectives: 1. Bones and joints of the shoulder 2. Organization of the shoulder’s muscles 3. Axilla - borders and contents 4. Organization of the brachial plexus Which joint serves as the only bony attachment of the upper limb to the axial skeleton? Sternal clavicular joint Anterior view Posterior view Which of these bones is commonly fractured? clavicle ORGANIZATION OF THE SHOULDER: MUSCLES AND INNERVATION * Muscles (MM) ATTACH HUMERUS TO AXIAL SKELETON: 1. Latissimus Dorsi ( thoracodorsal n. C6-C8 ) 2. Pectoralis Major ( lateral pectoral n. C5-C7, medial pectoral n. C8-Th1 ) - attaches to humerus * MM ATTACH HUMERUS TO THE SCAPULA } 1. Supraspinatus, Infraspinatus ( suprascapular n. C5-C6 ) 2. Subscapularis ( upper C5 and lower C6 subscapular nn. ) 3. Teres Minor ( axillary n. C5-C6 ) 4. Teres Major ( lower subscapular n. C6 ) 5. Deltoid ( axillary n. C5-C6 ) * MM ATTACH SCAPULA TO AXIAL SKELETON 1. Trapezius ( spinal accesory n. XI ) 2. Levator Scapulae, Rhomboids ( dorsal scapular n. C5 ) 3. Serratus Anterior ( long thoracic n. C5-C7 ) 4. Pectoralis Minor ( medial pectoral n. C8-Th1 ) rotator cuff Supraspinatus .: Assists the deltoid in the initial abduction Infraspinatus .: Powerful lateral rotator of humerus Teres minor .: Helps rotate the arm laterally and assists in adduction (like infraspinatus). HOWEVER, it is innervated by the axillary nerve, while the infraspinatus is innervated by the suprascapular nerve Subscapularis .: It is the primary medial rotator (also adducts it) .: Innervated by the subscapular nerve The deltopectoral triangle is also known as the “clavicopectoral triangle”. These two names tells me the exact borders. What’s in the triangle? The cephalic vein Which structures lie in the deltopectoral triangle? Cephalic vein The rotator cuff muscles work as a group in holding the head of the humerus in the glenoid cavity. They give protection and stability to the shoulder joint. Rotator cuff S I T S subscapularis Rotator cuff is formed by the tendons of: Supraspinatus , Infraspinatus, Teres minor and Subscapularis fuses with the joint capsule. What is the tendonitis of the rotator cuff? inflammation Axilla (the armpit) 1. Apex – cervicoaxillary canal, the passageway between the neck and the axilla. Lies between the 1st rib, clavicle and upper border of the scapula. 2. Base - formed by the skin, subcutaneous tissue and axillary fascia 3. Four walls: * anterior wall - pectoralis major and minor mm, pectoral and clavicopectoral fascia. Anterior axillary fold -> pectoralis major! * posterior wall - scapula , subscapularis m., latissimus dorsi m., teres major m. Posterior axillary fold -> latissimus dorsi and teres major! * medial wall - thoracic wall and serratus anterior m. * lateral wall - intertubercular groove of the humerus. Fun note: Axillary fossa = armpit What passes through the cervicoaxillary cannel? .: Arteries, veins, lymphatics and nerves to and from the arm What mainly forms the posterior wall? .: Scapula Contents of the axilla: • axillary artery and its branches • axillary vein and its tributaries • brachial plexus • axillary lymph vessels and lymph nodes • 3 muscles: long/short head of biceps brachii m. and coracobrachialis m. The axillary artery and vein, and the cords of brachial plexus (neurovascular bundle) are enveloped in the thin fascial sheath - axillary sheath. AXILLA ROOTS AND TRUNKS CORDS CLAVICLE AXILLARY ARTERY NEUROVASCULAR BUNDLE Axillary artery – three parts First part - one branch – superior thoracic a. Second part - two branches – thoracoacromial a. – lateral thoracic a. Third part - three branches – subscapular a. – anterior circumflex humeral a. Screw the lawyer, save the patient Superior thoracic Thoracodorsal Lateral thoracic Subscapular Anterior circumflex humeral Posterior circumflex humeral – posterior circumflex humeral a. The thoracoacromial artery will further branch off in 4 directions, named after parts of the body. Mnemonic: Cadavers Are Dead People Clavicular Acromial Deltoid Pectoral posterior circumflex humeral a. (3rd part) superior thoracic a. (1st part) anterior circumflex humeral a. (3rd part) thoracoacromial a. (2nd part) lateral thoracic a. (2nd part) subscapular a. (3rd part) circumflex scapular a. thoracodorsal a. Arterial anastomoses around the scapula .: Thoracoacromial artery -Cadavers are dead people -1. clavicular -2. acromial -3. deltoid -4. pectoral thyrocervical trunk Humeral loop: anterior circumflex humeral posterior circumflex humeral profunda brachii subscapular a. axillary a. anterior circumflex humeral a. deep branch of transverse cervical a. *(dorsal scapular) Scapular loop: Suprascapular Dorsal scapular Subscapular posterior circumflex humeral a. circumflex scapular a. profunda brachii a. Arterial anastomoses form loops Think about where the loops are located. That’s where they get the name. The anterior circumflex humeral, posterior circumflex humeral and profunda brachii are all wrapping around in the humerus The same goes for the scapular loop, which contains the suprascapular, dorsal scapular and subscapular ateries Five principal groups: 1. Pectoral( anterior) nodes receive lymph mainly from anterior thoracic wall and the breast and abdominal wall. 2. Subscapular (posterior) nodes receives lymph from posterior thoracic wall and scapular region. 3. Humeral (lateral) nodes receive lymph from upper limb. 4. Central nodes (base of axilla) receive lymph from anterior, posterior and lateral nodes. Drain into apical nodes. 5. Apical nodes (apex of axilla) Receive lymph from all the other nodes. Drain into the subclavian trunks. Axillary lymph nodes PLAN OF BRACHIAL PLEXUS = Ventral Rami C5 to T1 ROOTS (5) TRUNKS (3) DIVISIONS TERMINALS (5) MUSCULOCUTANEOUS (3/3) CORDS (3) C6 SUPERIOR A C5 MIDDLE LATERAL C7 C8 T1 P INFERIOR POSTERIOR A RADIAL MEDIAL DIVISIONS = ANTERIOR AND POSTERIOR AXILLARY MEDIAN ULNAR Which spinal nerves form the brachial plexus? C5, C6, C7 C8 and T1 Brachial plexus is formed by the union of the anterior (ventral) primary rami of C5 – T1 nerves that constitute roots of brachial plexus. The roots of brachial plexus unite to form three trunks: * superior trunk (C5-C6) * middle trunk (C7) * inferior trunk (C8-T1) Each trunk divides into anterior and posterior divisions of brachial plexus. The divisions of the trunks form three cords of brachial plexus: * posterior cord - posterior divisions of all three trunks * lateral cord – anterior divisions of superior and middle trunk * medial cord – anterior division of the inferior trunk The cords of brachial plexus give rise to most of the named peripheral nerves (branches) that result from the plexus formation. Basic Anatomy of the Brachial Plexus Musculocutaneous nerve Axillary nerve Lateral cord 5 Trunk 7 Radial nerve Median nerve Ventral rami 6 or roots Posterior cord 8 1 Medial cord Ulnar nerve Posterior divisions Anterior divisions BRACHIAL PLEXUS Roots, Trunks and Cords: Motor Distribution to Anterior and Posterior Shoulder Terminal Branches: Motor Distribution to Arm, Forearm and Hand CORDS OF BRACHAL PLEXUS - TERMINAL BRANCHES I. LATERAL CORD: 1. musculocutaneous n.(C5-C7): anterior group of arm (muscles of anterior arm are innervated; biceps, brachialis and coracobrachialis) 2. lateral root of median n.(C6-C7) : anterior group of forearm (except flexor carpi ulnaris, medial half of flexor digitorum profundum) thenar muscles and first two lumbricals Musculocutaneous nerve (C5,6,7) Coracobrachialis muscle Biceps brachii muscle Brachialis muscle Lateral cutaneous nerve of forearm Note the name: musculocutaneous It innervates the muscles in the arm and the cutaneous layer (skin) of the forearm What cord does this nerve spring from? The lateral cord. This is a pretty good way to remember what part of the forearm the musculocutaneous nerve innervates. Lateral anterior Lateral cord of brachial plexus Ulnar nerve Cutaneous innervation ( skin of lateral forearm) CORDS OF BRACHAL PLEXUS - TERMINAL BRANCHES II. MEDIAL CORD: 1. medial root of median n. (C8-T1): anterior group of forearm (except flexor carpi ulnaris, medial half of flexor digitorum profundum) thenar muscles and first two lumbricals 2. ulnar n. (C8-T1): flexor carpi ulnaris medial half of flexor digitorum profundum all the small muscles of the hand (except thenar and two first lumbricals) What did the lateral root of the median nerve innervate? .: thenar muscles, first two lumbricals, and anterior group of forearm except for flexor carpi ulnaris and medial half of flexor digitorum profundum Does the medial root of the median nerve innervate these exceptions? .: No, in fact it does the same thing as the lateral root (these cords join together to form the median nerve So what does innervate the flexor carpi ulnaris and the medial half of flexor digitorum profundum? .: ulnar nerve Anything else? .: All the small muscles of the hand except for the thenar and the first two lumbricals, which is what the median nerve takes care of. Note that the median nerve only cutaneously innervates the anterior part of the hand, and the back of the fingertips, not the rest of the back of the hand. Medial cord of brachial plexus Median nerve (C5,6,7,8,T1) Lateral cord of brachial plexus The pimp hand is felt with the radial nerve and the ulnar, I believe. Muscles of forearm Flexors of forearm except fl.carp.ulnaris and medial flexor dig. profundus Cutaneous innervation Palmar branch of median nerve Muscles of hand (thenar group and two first lumbricals) Common & proper digital nerves Note: Only muscles innervated by ulnar nerve shown Ulnar nerve (C7,8,T1) Medial epicondyle Cutaneous innervation Flexor dig. profundus (medial part) Flexor carpi ulnaris muscle Dorsal branch of ulnar nerve Deep & superficial branch of ulnar nerve Muscles of the hand (excluding thenar and two lumbrical muscles) Proper palmar digital nerves CORDS OF BRACHAL PLEXUS - TERMINAL BRANCHES III. POSTERIOR CORD: 1. axillary n. (C5-C6): deltoid, teres minor 2. radial n. (C5-T1): posterior group of arm and forearm In what situations the axillary nerve may be damaged (injured)? Fracture of the surgical neck Dislocation of the glenohumeral joint Compression from the incorrect use of crutches Radial nerve(C5,6,7,8) a Superficial and deep branch of radial nerve Posterior interosseous nerve (continuation of deep branch of Radial nerve) Superficial branch of radial nerve Dorsal digital nerves BRACHIAL PLEXUS – branches of ROOTS, TRUNKS AND CORDS DORSAL SCAPULAR C5 RHOMBOID MM AND LEVATOR SCAPULE SUPRASCAPULAR C5,6 SUPRASPINATUS M INFRASPINATUS M ROOTS C5 N. TO SUBCLAVIUS C5,6 SUBCLAVIUS C6 C7 LATERAL PECTORAL C5-C7 PECTORAL MM ROOTS TRUNKS C8 THORACODORSAL C6-C8 T1 LATISSIMUS DORSI M CORDS LONG THORACIC C5-C7 SERRATUS ANTERIOR M MEDIAL PECTORAL C8,T1 SUBSCAPULAR NN C5,6 SUBSCAPULARIS M TERES MAJOR M PECTORAL MM ARM muscles - action on shoulder and elbow Flexors (anterior compartment): * biceps brachii (both joints) - supination and flexion of forearm - flexion of arm * coracobrachialis (shoulder joint) - flexion and add. of arm * brachialis (elbow joint) - flexion of forearm in all position Extensors (posterior compartment): * triceps brachii (both joints) - extension of forearm - extension of arm (long h.) Anterior ( flexor) compartment Posterior (extensors) compartment Important spaces of the shoulder region Deltopectoral triangle – bounded by the clavicle superiorly, deltoid laterally and the pectoralis major (clavicular head) medially. Cephalic vein and deltoid branch of thoracoacromial artery. Quadrangular space – bounded superiorly by the teres minor and subscapularis, inferiorly by the teres major, medially by the long head of the triceps and laterally by the surgical neck of the humerus. Axillary nerve and posterior circumflex humeral artery and vein. Triangular space – superiorly by the teres minor, inferiorly by the teres major and laterally by the long head of triceps. Circumflex scapular vessels. Triangular interval - between the two heads of the triceps muscle, inferior to the teres major. Deep brachial artery and radial nerve. 1 – triangular space, 2 – quadrangular space, 3 – triangular interval 2 1 3 Brachial plexus injuries Injuries to the brachial plexus affect movements (paralysis) and cutaneous sensation (anesthesia). Signs and symptoms depend on the part of the plexus involved. Erb-Duchenne palsy is a paralysis of the arm caused by injury to the upper group of the arm's main nerves (specifically, spinal roots C5-C7), almost always occurring during birth. Depending on the nature of the damage, the paralysis can either resolve on its own over a period of months, necessitate physical therapy or require surgery. Dejerine-Klumpke (Klumpkes) palsy refers to paralysis of the lower brachial plexus. A rare condition where a lower spine lesion causes paralysis of the forearm and hand muscles. The lesion may occur during birth or as a result of infection, tumor or trauma. Questions of the day! 1. Which muscle is the primary supinator of the forearm? 1. Biceps brachii 2. Which muscle serves as the prime extensor of the forearm? 1. Triceps 3. If a tumor grows into the quadrangular space of the axillary region, which structures would be in danger? (Axillary nerve, posterior circumflex humeral) 1. Humeral loop 2. Brachial plexus 4. ****Which artery may be damaged during the fracture of the shaft of the humerus? 1. Posterior circumflex humeral artery