MBJ - Upper Limb
What is the shape of the axilla?
A pyramid
Where is the axilla located?
Between the upper arm and chest wall
How is the anterior wall of the axilla formed?
By the pectorals major, clavipectoral facia, pectorals major and subclavian muscle
What are the contribution is a post-fixed brachial plexus?
C4 is absent and T2 is present
What are the contribution in a pre-fixed brachial plexus?
C4 is present and T2 is absent
How are the trunks formed in the brachial plexus?
C5 and C6 - upper trunk C7 - middle trunk C8 and T1 - lower trunk
What are the contents of the upper triangular space?
Circumflex scapular artery
What are the boundaries of the base of the axilla?
Directed downwards and it formed by the skin and fascia
Where the axillary artery start and stop?
Extends from the outer border of the first rib to the lower border of the teres major muscle, beyond which it continues as the brachial artery
What are the boundaries of the apex of the axilla?
Front - clavicle Behind - superior border of scapula Medially - outer border of the first rib
What is the function of the rotator cuff?
Gives strength to the capsule of the shoulder joint all around except inferiorly.
What is the insertion, action and innervation of the pectorals major?
Insertion - lateral lip of bicipital groove of humerus Action - adduction and medial rotation of the shoulder Innervation - lateral and medial pectoral nerves
What are the boundaries of the cubital fossa?
Lat - medial border of brachioradialis Med - lateral border of the pronator teres Base - joining the 2 epicondyles of the humerus Apex - overlapping of medial and lateral boundaries Floor - brachialis above and supinator below
What are the branches of the lateral cord of the brachial plexus?
Lateral pectoral, lateral root of median nerve and musculocutaneous nerve
What are the boundaries of the lower triangular space?
Med - long head of triceps Lat - medial border of humerus Sup - teres major
What are the boundaries of the upper triangular space?
Med - teres minor Lat - long head of triceps Inf - teres major
What is the origin, insertion, action and innervation of the serratus anterior?
Origin - 8th digitation from the outer surface of upper 8 ribs Insertion - to the costal surface of the scapula along the medial border Action - pushing and punching movements, helps in forced inspiration Innervation - long thoracic nerve
What is the origin, insertion, action and innervation of the pectorals minor?
Origin - from 3rd -5th ribs near their costochondral junction Insertion - to the medial border and superior surface of Coracoid process of the scapula Action - draws the scapula forward, depresses the point of the shoulder and helps in forced inspiration Innervation - medial and lateral pectoral nerves
What muscles provide adduction of the shoulder and arm?
Pectoralis major, Teres major and latissimus dorsi
What muscles provide medial rotation of the shoulder?
Pectoralis major, subscapular, teres major and anterior fibres of deltoid
What are the 3 inter muscular spaces?
Quadrangular space, Upper triangular space and lower triangular space
What is Erb's point?
Region in upper trunk where 6 nerves meet. Injury results in Erb's paralysis
Why is the shoulder joint a weak joint?
Structurally the glenoid cavity is too small and shallow to hold the head of the humerus in place
What are the boundaries of the quadrangular space?
Sup - supscapularis, capsular ligament of shoulder joint, teres minor Inf - teres major Med - long head of triceps Lat - surgical neck of humerus
How is the stability of the shoulder joint maintained?
The coracromial arch, musculotendinous cuff of the shoulder and the glenoidal labrum
What are the branches of the posterior cord of the brachial plexus?
Upper subscapular nerve, lower subscapular nerve, thoracodorsal nerve, radial nerve and axillary nerve
What is the clinical importance of the median cubital vein?
Vein of choice for IV injections, collecting blood samples, and cardiac catheterizations
How is the brachial plexus formed?
Ventral rami of C5-T1 spinal nerves
What does each trunk divide into?
anterior and posterior divisions
What muscles provide flexion of the shoulder?
anterior fibres of deltoid, clavicular fibres of Pectoralis major
What are the ligaments of the shoulder joint?
articular capsule, glenohumeral ligament, coracohumeral ligament, transverse humeral ligament and the glenoidal labrum
What are the contents of the quadrangular space?
axillary nerve and posterior circumflex humeral artery
Where is the weakest junction in the clavicle?
between the medial 2/3 and the lateral 1/3
What are the contents of the cubital fossa?
biceps tendon, brachial artery, median nerve, radial nerve, ulnar artery and radial artery
What are the contents of the axilla?
brachial plexus, axillary artery and vein, lymph nodes, and axillary pad of fat and areolar tissue
What is the clavipectoral fascia pierced by?
cephalic vein, thoracoacromial artery and lymphatics, lateral pectoral nerve
How does winging of the scapula occur?
damage to the long thoracic nerve
What is Smith's fracture?
distal segment being palmar flexed rather than dorsified
What is a Colles fracture?
fracture of the distal radius with displacement upwards and backwards
What muscles provide lateral rotation of the shoulder?
infraspinatus, teres minor, posterior fibres of deltoid
What causes wrist drop?
injury to radial nerve
What causes Klumpke's paralysis?
injury to the lower trunk roots (C8-T1)
What causes claw hand?
injury to ulnar nerve
What are the branches of the medial cord of the brachial plexus?
medial pectoral, medial cutaneous nerve of the arm and forearm, median root of the median nerve and ulnar nerve
What are peculiarities of the clavicle?
only long bone to ossify in membrane, ossifies from 2 primary centres and has no medullary cavity
What muscles provide extension of the shoulder?
posterior fibres of deltoid and latissimus dorsi
What are the contents of the lower triangular space?
radial nerve and profunda brachii vessels
What are the carpal bones in the proximal row?
scaphoid, lunate, triquetrum, pisiform
What is the articulation of the shoulder joint?
scapula and head of the humerus
What are the branches of the third part of the axillary artery?
subscapular artery (latissimus dorsi, serratus anterior) Anterior circumflex artery (shoulder joint) Posterior circumflex artery (deltoid, triceps, and shoulder joint)
How is the posterior wall of the axilla formed?
subscapularis, Peres major and latissimus dorsi
what are the muscles that make up the musculotendinous cuff?
subscapularis, supraspinatus, infraspinatus and teres minor muscles
What are the branches of the first part of axillary artery?
superior thoracic artery that supplies the pectoral muscles
What type of joint is the shoulder joint?
synovial ball and socket joint
What are the branches of the second part of the axillary artery?
thoracoacromial trunk (deltoid, acromial, pectoral and clavicular branches) Lateral thoracic artery (pectoral muscles and breast)
What are the carpal bones in the distal row?
trapezium, trapezoid, capitate, hamate
Where are breath sounds supposed to be heard the best?
triangle of auscultation in the back
How is the medial wall of the axilla formed?
upper 4 ribs with their intercostal muscles and upper 4 digitations of the serratus anterior
How is the lateral wall of the axilla formed?
upper part of shaft of humerus
