Week 2 Lecture Notes PDF

Gross Anatomy II Home Upper Extremity Nerve Innervati… Week 14 Lecture Notes Week 2 Lecture Notes : https://sites.google.com/view/grossanatomyii/week-2-lecture-notes 5/10/24, 4 53 PM Page 1 of 26 The Axilla Objectives 1. Name the structures that form the apex, base and walls of the axilla 2. List th...

Gross Anatomy II Home Upper Extremity Nerve Innervati… Week 14 Lecture Notes Week 2 Lecture Notes : https://sites.google.com/view/grossanatomyii/week-2-lecture-notes 5/10/24, 4 53 PM Page 1 of 26 The Axilla Objectives 1. Name the structures that form the apex, base and walls of the axilla 2. List the contents of the axilla 3. Describe the origin, termination, anatomical relations and branches of the axillary artery 4. Name the arteries that participate in the arterial anastomoses around the scapula and discuss their clinical significance 5. Describe the origin, termination, anatomical relations and tributaries of the axillary vein 6. List the groups of axillary lymph nodes and indicate the territory drained by each of them 7. Describe the roots, trunks, divisions, cords and branches of the brachial plexus 8. Discuss common disorders affecting the structures of the axilla So besides calling it your armpit, what is the axilla? It is a pyramidal-shaped space between upper part of arm and side of thorax It is an important passage for nerves, blood vessels and lymph vessels traveling between root of neck and upper limb It has an has an apex, a base and 4 walls (anterior, posterior, medial and lateral) apex (cervico-axillary canal): directed toward root of neck boundaries of apex: : https://sites.google.com/view/grossanatomyii/week-2-lecture-notes 5/10/24, 4 53 PM Page 2 of 26 boundaries of apex: anteriorly: posterior border of clavicle posteriorly: superior border of scapula medially: lateral border of 1st rib boundaries of the base anteriorly: anterior axillary fold (formed by pectoralis major) posteriorly: posterior axillary fold (formed by teres major and latissimus dorsi) medially: thoracic wall (The base is formed by skin stretching from anterior to posterior axillary folds) Walls of the axilla: anterior wall: pectoralis major, pectoralis minor, subclavius and clavipectoral fascia (fascia that encloses subclavius and pectoralis minor muscles) posterior wall: scapula, subscapularis, teres major and latissimus dorsi medial wall: upper 4 ribs and intercostal spaces between them, covered by serratus anterior lateral wall (narrowest): bicipital (intertubercular) groove of humerus : https://sites.google.com/view/grossanatomyii/week-2-lecture-notes 5/10/24, 4 53 PM Page 3 of 26 Boundaries of axilla : https://sites.google.com/view/grossanatomyii/week-2-lecture-notes 5/10/24, 4 53 PM Page 4 of 26 Sagittal cross section of axilla. Contents of the Axilla axillary artery and its branches axillary vein and its tributaries axillary lymph nodes and lymph vessels brachial plexus (cords and their branches) : https://sites.google.com/view/grossanatomyii/week-2-lecture-notes 5/10/24, 4 53 PM Page 5 of 26 As you can see, there are a lot of structures within the axilla. This is why we have a natural instinct to protect this area (Think about what you do if someone tickles you...) As you can see... A lot of structures run through our axilla. This is why we have a natural need to protect this area. Think about what you do when you are tickled... Look at this photo of the axilla, and try to label what you see. Axillary Artery : https://sites.google.com/view/grossanatomyii/week-2-lecture-notes 5/10/24, 4 53 PM Page 6 of 26 begins at lateral border of 1st rib as a continuation of subclavian artery ends at inferior border of teres major, where it becomes brachial artery surrounded by cords of brachial plexus and their branches pectoralis minor crosses in front of axillary artery and divides artery into 3 parts: 1st part: from lateral border of 1st rib to medial border of pectoralis minor 2nd part: posterior to pectoralis minor 3rd part: from lateral border of pectoralis minor to inferior border of teres major : https://sites.google.com/view/grossanatomyii/week-2-lecture-notes 5/10/24, 4 53 PM Page 7 of 26 : https://sites.google.com/view/grossanatomyii/week-2-lecture-notes 5/10/24, 4 53 PM Page 8 of 26 1st part: superior thoracic artery: small artery that helps to supply upper two intercostal spaces 2nd part: thoracoacromial artery (trunk): originates close to medial border of pectoralis minor and pierces clavipectoral fascia and gives off clavicular, acromial, pectoral and deltoid branches lateral thoracic artery: originates close to lateral border of pectoralis minor and follows the lateral border of pectoralis minor to thoracic wall and supplies pectoralis muscles, serratus anterior and lateral part of breast 3rd part: subscapular artery: usually largest branch of axillary artery à descends on subscapularis muscle and divides into circumflex scapular and thoracodorsal arteries circumflex scapular: curves around lateral border of scapula (in triangular space) to supply muscles on posterior aspect of scapula thoracodorsal artery: inferior continuation of subscapular artery and supplies muscles on posterior wall of axilla and ends in latissimus dorsi muscle anterior circumflex humeral artery: skirts anterior part of surgical neck of humerus posterior circumflex humeral artery: larger than anterior circumflex and passes through quadrangular space with axillary nerve and skirts posterior part of surgical neck of humerus and anastomoses with anterior circumflex humeral artery : https://sites.google.com/view/grossanatomyii/week-2-lecture-notes 5/10/24, 4 53 PM Page 9 of 26 Axillary Vein begins at inferior border of teres major muscle as a continuation of basilic vein ascends anterior and medial to axillary artery terminates at lateral border of 1st rib, where it becomes subclavian vein tributaries: correspond with branches of axillary artery + cephalic vein (brachial veins may drain into basilic or axillary veins) Axillary Lymph Nodes central lymph nodes: lie in center of axilla à receive lymph from previous 3 groups apical lymph nodes: lie at apex of axilla à receive lymph from all other axillary nodes as well as from lymph vessels accompanying cephalic vein à efferent vessels from apical group join to form subclavian lymph trunk subclavian lymph trunk drains into thoracic duct (left side) and into right lymphatic duct (right side), or it may drain separately at junction of internal jugular and subclavian veins : https://sites.google.com/view/grossanatomyii/week-2-lecture-notes 5/10/24, 4 53 PM Page 10 of 26 Brachial Plexus From proximal to distal, the brachial plexus consists of roots, trunks, divisions, cords and terminal branches roots roots are ventral rami of spinal nerves C5-C8 and most of ventral ramus of T1 (with the exception of first intercostal nerve) trunks ventral rami of C5 and C6 join and form superior trunk : https://sites.google.com/view/grossanatomyii/week-2-lecture-notes 5/10/24, 4 53 PM Page 11 of 26 ventral rami of C5 and C6 join and form superior trunk ventral ramus of C7 forms middle trunk ventral rami of C8 and T1 join and form inferior trunk divisions each trunk branches into anterior and posterior divisions cords posterior divisions of 3 trunks join and form posterior cord anterior divisions of superior and middle trunks join and form lateral cord anterior division of inferior trunk forms medial cord terminal branches each cord gives off 2 terminal branches: posterior cord gives off axillary nerve (C5, 6) and radial nerve (C5, 6, 7, 8, T1) lateral cord gives off musculocutaneous nerve (C5, 6, 7) and lateral root of median nerve medial cord gives off ulnar nerve (C7, 8, T1) and medial root of median nerve median nerve, formed by union of its lateral and medial roots, contains C6, 7, 8, T1 fibers other branches of brachial plexus: from superior trunk: nerve to subclavius (C5, 6) suprascapular nerve (C5, 6) from posterior cord: upper subscapular nerve and lower subscapular nerve (C5, 6) thoracodorsal nerve (C6, 7, 8) from lateral cord: lateral pectoral nerve (C5, 6, 7) from medial cord: : https://sites.google.com/view/grossanatomyii/week-2-lecture-notes 5/10/24, 4 53 PM Page 12 of 26 medial pectoral nerve (C8, T1) medial cutaneous nerve of arm (medial brachial cutaneous nerve) T1 medial cutaneous nerve of forearm (medial antebrachial cutaneous nerve) C8, T1 Brachial_plexus.jpg:Mattopaedia at en.wikipediaderivative work: Captain-n00dle (talk), MissMJ, Public domain, via Wikimedia Commons The Arm and Cubital Fossa : https://sites.google.com/view/grossanatomyii/week-2-lecture-notes 5/10/24, 4 53 PM Page 13 of 26 Objectives 1. Name the nerves that provide sensory innervation to the skin of the arm and describe their distribution 2. Name the superficial and deep veins of the arm and describe their course and termination 3. Describe the origin, insertion, action and nerve supply of the muscles of the anterior and posterior compartments of the arm 4. Describe the origin, termination, anatomical relations and branches of the brachial artery 5. Describe the course, anatomical relations and branches of the musculocutaneous and radial nerves in the arm. 6. Describe the course and anatomical relations of the median and ulnar nerves in the arm 7. Describe the boundaries, floor, roof and contents of the cubital fossa 8. Discuss common disorders affecting the structures of the arm and cubital fossa Cutaneous Innervation of the Arm The skin over point of shoulder and halfway down deltoid muscle is supplied by supraclavicular nerves (branches of cervical plexus) The skin over lower half of deltoid is supplied by upper lateral cutaneous nerve of arm (superior lateral brachial cutaneous nerve). This is a branch of axillary nerve. The skin over lateral arm below deltoid is supplied by the lower lateral cutaneous nerve of arm (inferior lateral brachial cutaneous nerve). This is branch of radial nerve The skin of base of axilla and medial aspect of arm: medial cutaneous nerve of arm (medial brachial cutaneous nerve). This is a branch of medial cord of brachial plexus intercostobrachial nerve (lateral cutaneous branch of 2nd intercostal nerve) The skin of back of arm is supplied by the posterior cutaneous nerve of arm (posterior brachial cutaneous nerve). This is a branch of radial nerve : https://sites.google.com/view/grossanatomyii/week-2-lecture-notes 5/10/24, 4 53 PM Page 14 of 26 : https://sites.google.com/view/grossanatomyii/week-2-lecture-notes 5/10/24, 4 53 PM Page 15 of 26 Superficial Veins of the Arm cephalic vein: originates from lateral side of dorsal venous arch of hand à ascends in superficial fascia on lateral aspect of arm à pierces deep fascia and runs superiorly and medially between pectoralis major and deltoid muscles (in deltopectoral triangle) à passes deep to clavicular part of pectoralis major and drains into axillary vein basilic vein: originates from medial side of dorsal venous arch of hand à ascends in superficial fascia on medial side of arm à halfway up the arm pierces deep fascia à at lower border of teres major muscle becomes continuous with axillary vein Compartments of the Arm · arm is surrounded by a sheath of deep fascia · medial and lateral intermuscular septa extend from deep fascia to humerus and divide arm into anterior and posterior compartments · each compartment has its muscles, nerves and vessels : https://sites.google.com/view/grossanatomyii/week-2-lecture-notes 5/10/24, 4 53 PM Page 16 of 26 : https://sites.google.com/view/grossanatomyii/week-2-lecture-notes 5/10/24, 4 53 PM Page 17 of 26 THE ANTERIOR COMPARTMENT Muscles of the Anterior Compartment · · · biceps brachii coracobrachialis brachialis All muscles are supplied by musculocutaneous nerve Coracobrachialis (pierced by the musculocutaneous nerve) Bony Attachments: 1: Coracoid process of the scapula. 2: medial mid-shaft humerus. Innervation: Musculocutaneous nerve (C5,6). Arterial Supply: Brachial a. Action: Flexes and adducts the arm. Biceps Brachii Bony Attachments: 1: Short head : tip of the coracoid process of the scapula; Long head: supraglenoid tubercle of the scapula. 2: radial tuberosity of the radius. Innervation: Musculocutaneous nerve (C5,6). Arterial Supply: Brachial a. Action: Flexes the forearm, flexes arm (long head), supinates. Brachialis : https://sites.google.com/view/grossanatomyii/week-2-lecture-notes 5/10/24, 4 53 PM Page 18 of 26 Brachialis Bony Attachments: 1: Anterior surface of the lower one-half of the humerus and the associated intermuscular septum. 2: Coronoid process of the ulna. Innervation: Musculocutaneous nerve (C5,6). Arterial Supply: Brachial a., radial recurrent a. Action: Flexes the forearm. Vessels of the anterior compartment Brachial Artery · begins at lower border of teres major muscle, as a continuation of axillary artery · runs along medial aspect of arm, accompanied by median nerve and passes deep to bicipital aponeurosis to enter cubital fossa · terminates in cubital fossa by dividing into radial and ulnar arteries (terminal branches) Branches of the Brachial Artery muscular branches (supply muscles of anterior compartment of arm) profunda brachii artery (deep brachial artery, deep artery of arm): originates near beginning of brachial artery and passes through triangular interval (with radial nerve) to enter posterior compartment of arm, which it supplies and gives off its terminal branches (radial collateral and middle collateral arteries) participate in arterial anastomosis around elbow joint superior ulnar collateral artery: accompanies ulnar nerve and participates in arterial anastomosis around elbow joint inferior ulnar collateral artery: participates in arterial anastomosis around elbow joint radial and ulnar arteries (terminal branches) : https://sites.google.com/view/grossanatomyii/week-2-lecture-notes 5/10/24, 4 53 PM Page 19 of 26 Henry Vandyke Carter, Public domain, via Wikimedia Commons : https://sites.google.com/view/grossanatomyii/week-2-lecture-notes 5/10/24, 4 53 PM Page 20 of 26 Brachial Veins · accompanying veins (venae comitantes) of brachial artery are paired veins that run along medial and lateral sides of brachial artery · begin at elbow by union of accompanying veins of radial and ulnar arteries · receive tributaries that correspond with branches of brachial artery · have numerous anastomoses with each other and with superficial veins · brachial veins drain into axillary vein or into basilic vein before it becomes axillary vein Nerves of the anterior compartment Musculocutaneous Nerve · · terminal branch of lateral cord of brachial plexus pierces coracobrachialis and runs inferiorly and laterally between biceps brachii and : https://sites.google.com/view/grossanatomyii/week-2-lecture-notes 5/10/24, 4 53 PM Page 21 of 26 pierces coracobrachialis and runs inferiorly and laterally between biceps brachii and brachialis, lateral to tendon of biceps brachii pierces deep fascia and becomes superficial and then runs down lateral aspect of forearm as lateral cutaneous nerve of forearm (lateral antebrachial cutaneous nerve) · branches: o muscular branches supply coracobrachialis, biceps brachii and brachialis o cutaneous branch- lateral cutaneous nerve of forearm supplies skin along lateral aspect of forearm as far as root of thumb o articular branch to elbow joint · Median Nerve originates by two roots, one from medial cord and one from lateral cord of brachial plexus runs in arm with brachial artery. It is first lateral to brachial artery, then in middle of arm passes anterior to artery, crossing it from lateral to medial and descends medial to artery in lower arm, where it passes under bicipital aponeurosis to enter cubital fossa · gives off no branches in arm · · Ulnar Nerve terminal branch of medial cord of brachial plexus runs down the arm medial to brachial artery and passes posterior to medial epicondyle of humerus (in this location is superficial and vulnerable to injury referred to in lay terms as “funny bone”) gives off no branches in arm · · THE POSTERIOR COMPARTMENT Triceps Brachii (the muscle of the posterior compartment) Bony Attachments: 1: Long head: infraglenoid tubercle of the scapula; Lateral head: posterolateral humerus & lateral intermuscular septum; Medial head: posteromedial surface of the inferior humerus. 2: Olecranon process of the ulna. Innervation: Radial nerve. Arterial Supply: Deep brachial (profunda brachii) a. : https://sites.google.com/view/grossanatomyii/week-2-lecture-notes 5/10/24, 4 53 PM Page 22 of 26 Arterial Supply: Deep brachial (profunda brachii) a. Action: Extends the forearm; the long head extends and adducts arm. Radial Nerve (the nerve of the posterior compartment) terminal branch of posterior cord of brachial plexus passes through triangular interval (with profunda brachii vessels) to enter posterior compartment of arm and runs inferiorly and laterally in radial (spiral) groove, on posterior surface of humeral shaft (area where can be damaged by fracture of humeral shaft). · · In lower arm, it pierces lateral intermuscular septum and enters anterior compartment, where runs inferiorly between brachialis (medial to nerve) and brachioradialis (lateral to nerve). It will travel anterior to lateral epicondyle of humerus and then divide into superficial and deep branches (terminal branches). : https://sites.google.com/view/grossanatomyii/week-2-lecture-notes 5/10/24, 4 53 PM Page 23 of 26 : https://sites.google.com/view/grossanatomyii/week-2-lecture-notes 5/10/24, 4 53 PM Page 24 of 26 Cubital Fossa · · · · triangular depression anterior to elbow joint boundaries: o medially: pronator teres o laterally: brachioradialis o superiorly: line connecting medial and lateral epicondyles of humerus floor: brachialis and supinator muscles roof: deep fascia of forearm, reinforced by bicipital aponeurosis o median cubital vein is located in superficial fascia overlying fossa and connects cephalic and basilic veins : https://sites.google.com/view/grossanatomyii/week-2-lecture-notes 5/10/24, 4 53 PM Page 25 of 26 also in superficial fascia overlying fossa are branches of medial and lateral cutaneous nerves of forearm contents of cubital fossa: median nerve, brachial artery (with its two terminal branches: ulnar and radial arteries) and accompanying veins, tendon of biceps brachii, radial nerve (with its two terminal branches: superficial and deep) : https://sites.google.com/view/grossanatomyii/week-2-lecture-notes 5/10/24, 4 53 PM Page 26 of 26