Axilla and Arm Flashcards
Explain the boundaries and contents of the axilla
Boundaries:
The apex is the 1st rib and clavicle
The base is the skin of armpit
The anterior boundaries are the pectoral muscles
The posterior boundaries are the scapula and subscapula muscle
The medial boundaries are the thoracic wall and serratus anterior muscle
The lateral boundaries are the humerus
Contents:
Axillary artery, axillary vein, axillary lymph nodes, and 3 cords of the brachial plexus
Name the common spinal cord segments present in the 16 peripheral nerves of the brachial plexus
Dorsal scapular nerve - C4-5 Long thoracic nerve - C5-7 Suprascapular nerve - C4-6 Subclavian nerve - C5-6 Lateral pectoral nerve - C5-7 Musculocutaneous nerve - C5-7 Median nerve - C5-7 (lateral root), C8-T1 (medial root) Medial pectoral nerve - C8-T1 Medial cutaneous nerve of arm - C8-T1 Medial cutaneous nerve of forearm - C8-T1 Ulnar nerve - C7-T1 Upper subscapular nerve - C5-6 Thoracodorsal nerve - C6-8 Lower subscapular nerve - C5-6 Axillary nerve - C5-6 Radial nerve - C5-T1
Name the functions (sensory, motor, postgang symp) of the axons present in the peripheral nerves of the brachial plexus
Dorsal scapular nerve - postganglionic sympathetic and motor (not sensory) to levator scapulae and rhomboid muscles
Long thoracic nerve - sensory, postganglionic sympathetic, and motor to serratus anterior muscle
Suprascapular nerve - sensory, postganglionic sympathetic, and motor innervation of the supraspinatus and infraspinatus muscles
Subclavian nerve - sensory, postganglionic sympathetic, and motor innervation of the subclavius muscle
Lateral pectoral nerve - sensory, postganglionic sympathetic, and motor innervation of the pectoralis major and minor muscles
Musculocutaneous nerve - (muscular branches) sensory, postganglionic sympathetic, and motor innervation of the biceps brachii, coracobrachialis, and brachialis muscles; (lateral cutaneous nerve of forearm) sensory and postganglionic sympathetic innervation of skin overlying the lateral aspect of the forearm
Median nerve - lateral and medial root: (muscular branches in the forearm) sensory, postganglionic sympathetic & motor innervation of the flexor carpi radialis, palmaris longus, flexor digitorum superficialis, & pronator teres muscles, (anterior interosseous nerve) sensory, postganglionic sympathetic & motor innervation of the flexor pollicis longus, flexor digitorum profundus & pronator quadratus muscles, (palmar cutaneous branch) sensory & postganglionic sympathetic innervation of the skin overlying the radial aspect of the palm of the hand, (muscular branches in the hand) sensory, postganglionic sympathetic & motor innervation of the lateral two lumbrical muscles, (recurrent branch of the median nerve) sensory, postganglionic sympathetic & motor innervation of the flexor pollicis brevis, abductor pollicis brevis & opponens pollicis muscles, (common and proper palmar digital nerves) sensory & postganglionic sympathetic innervation of the skin overlying digits 1-4
Medial pectoral nerve - sensory, postganglionic sympathetic & motor innervation of the pectoralis major & minor muscles
Medial cutaneous nerve of arm and forearm - sensory & postganglionic sympathetic innervation of the skin overlying the medial aspect of the arm & forearm
Ulnar nerve - (muscular branches in the forearm) sensory, postganglionic sympathetic & motor innervation of the flexor carpi ulnaris & flexor digitorum profundus muscles, (palmar (cutaneous) branch) sensory and postganglionic sympathetic innervation of the skin overlying the ulnar side of the palm –> common palmar digital nerves and proper palmar digital nerves, (dorsal (cutaneous) branch) sensory and postganglionic sympathetic innervation of the skin overlying the dorsal surfaces of digits 4 and 5, (deep (terminal) branch) sensory, postganglionic sympathetic, and motor innervation of the abductor digiti minimi, flexor digiti minimi, flexor pollicis brevis, opponens digiti minimi, palmar interossei, dorsal interossei, medial two lumbricals, and adductor pollicis muscles
Upper subscapular nerve - sensory, postganglionic sympathetic, and motor innervation of the subscapularis muscle
Thoracodorsal nerve - sensory, postganglionic sympathetic, and motor innervation of latissimus dorsi muscle
Lower subscapular nerve - sensory, postganglionic sympathetic, and motor innervation of subscapularis and teres major muscles
Axillary nerve - (muscular branches in the arm) sensory, postganglionic sympathetic innervation of the deltoid and teres minor muscles, (superior lateral cutaneous nerve of the arm) sensory and postganglionic sympathetic innervation of the skin overlying the superior lateral aspect of the arm
Radial nerve - (muscular branches in the arms) sensory, postganglionic sympathetic, and motor innervation of the triceps brachii, and brachialis muscles, (muscular branches in the forearm) sensory, postganglionic sympathetic, and motor innervation of the anconeus, brachioradialis, supinator, extensor carpi ulnaris, extensor digitorum, extensor pollicis longus, and abductor pollicis longus muscles, (posterior cutaneous nerve of forearm) sensory and postganglionic sympathetic innervation of the skin overlying the posterior aspect of the forearm, (superficial (terminal) branch) sensory and postganglionic sympathetic innervation of the skin overlying the radial side of the dorsum of the hand
Apply the convention for naming spinal nerves as they exit the vertebral column to the spinal nerves of the brachial plexus
Cervical spinal nerves exit above their corresponding vertebrae: C6 nerve = C5-6
All other spinal nerves exit below their corresponding vertebrae: T7 nerve = T7-T8
Use a drawing of the brachial plexus to locate a point that a single lesion would explain patient findings (sensory and motor deficits)
Draw draw draw
Describe the location and contents of the following neurovascular tracts: triangular space, triceps hiatus
Triangular space:
Location - teres minor, teres major, and long head of triceps brachii
Contents - circumflex scapular artery
Triceps hiatus:
Location - long head of triceps brachii, and teres major as superior border
Contents - radial nerve and profunda brachii artery
Describe the fascial compartments of the anterior and posterior arm and list their contents, general actions, innervation, and blood supply
Anterior compartment: Muscles - Function - shoulder and elbow flexion Innervation - musculocutaneous nerve Arterial supply - brachial artery
Posterior compartment: Muscles - Function - shoulder and elbow extension Innervation - radial nerve Arterial supply = profunda brachii artery Anconeus also in this compartment
Predict the most common direction of dislocation of the shoulder based on the structure of the joint capsule and ligaments
Anterior dislocation - head of humerus moves inferiorly then anteriorly because the ligaments and joint capsule on the anterior aspect would pull humerus forward; inferior joint capsule is not reinforced by rotator cuff or ligaments
Predict what neurovascular structures would be injured based on bone fracture located at the surgical neck of the humerus, radial groove of the humerus
Quandrangular space (axillary nerve and posterior circumflex humeral artery) would be injured for surgical neck of humerus Triceps hiatus (radial nerve and profunda brachii artery) would be injured for radial groove of humerus
Locate the areas of skin associated with a single spinal segment/nerve (dermatome)
Relevant dermatomes:
C5, C6, C7, C8, T1
Describe territories and path of drainage of axillary lymph nodes to the venous system
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Identify structures from the Cross Section ID List on the Biceps Brachii Muscle Level photograph on Kenhub.com
Check and draw screenshot
Brachialis innervations (including spinal cord segments)
Musculocutaenous nerve and small branch from radial nerve (C5-6)
Coracobrachialis innervations (including spinal cord segments)
Musculocutaneous nerve (C6-7)
Triceps brachii innervations (including spinal cord segments)
Radial nerve (C6-T1)
