TBL13 Flashcards
Pectoral muscles are derivatives of what?
parietal mesoderm
Pectoralis major attachments
sternocostal and clavicular heads of the pectoralis major attach to the sternum, superior six costal cartilages, and clavicle proximally and to the humerus distally
Pectoralis major function
simultaneous contraction of the two heads adducts the upper extremity and medially rotates the arm at the glenohumeral joint
Serratus anterior attachments
attaches to lateral portions of the 1st to 8th ribs proximally and to the medial border of the scapula distally
Serratus anterior function
protracts the scapula when reaching for something and recall the trapezius and rhomboids retract the protracted scapula
Pectoralis minor attachments
deep to the pectoralis major, attaches to the 3rd to 5th ribs proximally and to the coracoid process of the scapula distally
Pectoralis minor function
pectoralis minor stabilizes the scapula against the posterior thoracic wall during protraction
Serratus anterior with the superior and inferior parts of the trapezius synergistically?
rotate the scapula upward allowing the deltoid to fully abduct the upper extremity from the horizontal plane
Lateral pectoral nerve
innervates the clavicular head of the pectoralis major
Medial pectoral nerve
innervates both the sternocostal head and the pectoralis minor
Long thoracic nerve
innervates the serratus anterior
Which muscles are absent or partially lost in the Poland sequence defect?
absence of the pectoralis minor and partial loss of the pectoralis major (usually the sternal head) -> nipple and areola are absent of displaced, fused digits, short digits
Why is the long thoracic nerve vulnerable to injury and how are abduction and rotation at the glenohumeral joint hindered after its injury? How does the winged scapula deformation occur?
the long thoracic nerve courses on the superficial aspect of the serratus anterior; after injury, the medial border of the scapula moves laterally and posteriorly away from the thoracic wall -> winged scapula
Deep fascia
sheet of dense connective tissue named by the tissue it covers
Pectoral fascia
fascia leaves the lateral border of the pectoralis major to become the axillary fascia, which surrounds the neurovascular contents of the axilla
Boundaries of the axilla
subscapularis, serratus anterior, and pectoralis major form the posterior, medial, and anterior boundaries, respectively
Axilla connects what to where?
determine nerves and blood vessels pass from the root of the neck through the axilla into the upper extremity
Axillary artery
continues from the subclavian artery at the lateral border of the first rib and envision its proximal branches (ignore names) supply the pectoralis major and minor and the serratus anterior
Blood supply of the deltoids
posterior circumflex humeral and anterior circumflex humeral arteries arise from the axillary artery and anastomose around the humerus to supply the deltoid
Subscapular artery
arises from the axillary artery, is a very short artery, then divides into the thoracodorsal artery (latissimus dorsi) and the circumflex scapular artery (teres major and minor)
Circumflex scapular artery
supplies the teres major and minor, anastomoses on the posterior surface of the scapula with the suprascapular artery, a branch of the subclavian artery that supplies the supraspinatus and infraspinatus
Dorsal scapular artery
another branch of the subclavian artery, supplies the levator scapulae and rhomboids and contributes to the anastomoses on the posterior scapula
Brachial artery
axillary artery continues as the brachial artery at the inferior border of the teres major
Where can the axillary artery be ligated without stopping blood flow into the ipsilateral upper extremity?
ligated between the 1st rib and subscapular artery; subclavian to suprascapular artery to circumflex scapular artery bypasses
Axillary vein
receives venous tributaries corresponding to branches of the axillary artery
Lymphatic vessels of the upper extremity
accompany the axillary vein tributaries and drain into the axillary lymph nodes
Efferent lymph vessels from the axillary nodes drain into?
drain into the supraclavicular nodes
Efferent lymph vessels from the supraclavicular lymph nodes drain into?
drain into the veins in the root of the neck
Which two nerves are at risk during surgical removal of pathologic axillary nodes? Why can removal result in lymphedema?
Long thoracic nerve and thoracodorsal nerve; removal of LNs result in lymphedema because lymphatic drainage is impeded
What comprise the roots of the brachial plexus?
anterior rami of spinal nerves C5-T1
Organization of brachial plexus starting from closest to vertebral column?
root, trunk, division, cord, branches
“Run To Drink Cold Beer”
What form the superior, middle, and inferior trunks of the brachial plexus?
C5-C6, C7, C8-T1; respectively
What nerve orginates from C5?
dorsal scapular nerve
What roots generate the long thoracic nerve?
C5-C7, “5,6,7 wings to heaven -> wing scapula”
What generates the suprascapular nerve?
superior trunk
What form the lateral, medial, and posterior cords?
anterior and posterior divisions of the trunks
Deltoid, pectoral, and axillary fasciae continue inferiorly as?
brachial fascia that encloses the arm like a snug sleeve
Head, neck, and tuberosity of the radius
radial tuberosity (biceps long and short heads attach distally)
Coronoid process and tuberosity of the ulna
brachialis attach distally to both
Long head of the biceps attachments
intertubercular sulcus guides the long head to its proximal attachment on the supraglenoid tubercle of the scapula and attaches to the radial tuberosity distally
Short head of the biceps attachments
attaches to the coracoid process proximally and to the radial tuberosity distally
Biceps function
flexes the forearm, and when walking or running the long head synergizes with the anterior part of the deltoid to flex the arm at the shoulder joint
Where is the tendon of the long head of the biceps commonly ruptured and what deformity results?
Commonly ruptured in the intertubercular sulcus of the humerus (after wear and tear of an inflammed tendon) -> tears attachment to the supraglenoid tubercle, resulting in the detached muscle belly forming a ball near the center of the distal part of the anterior aspect of the arm (Popeye deformity)
Supination and pronation of the forearm
Supination - palm up; pronation - palm down
Biceps role in supination/pronation
flexes the forearm when it is supinated but the biceps becomes the main supinator of the forearm and hand when the forearm is pronated
Brachialis attachments
attaches to the inferior half of the humerus proximally and to the coronoid process and tuberosity of the ulna distally
Brachialis function
flexes the forearm when it is either pronated or supinated
Coracobrachialis attachments
attaches to the coracoid process proximally (deep to the short biceps head) and to the middle third of the humerus distally (medial to the the brachialis proximal attachment)
Coracobrachialis function
assists the anterior part of the deltoid and long head of the biceps during flexion of the arm at the shoulder joint
Musculocutaneous nerve
arises from spinal cord segments C5 and C6, eventually branches off from the lateral cord of the brachial plexus -> innervates the biceps, brachialis, coracobrachialis
Which spinal cord segments are tested by the biceps tendon reflex?
examiner’s thumb firmly on biceps tenon, tap at base of nail bed, positive if involuntary contraction of biceps; tests C5 and C6 spinal cord segments
Posterior cord of the brachial plexus branches into what 2 nerves before bifurcating into the terminal branches?
thoracodorsal and subscapular nerves
Posterior cord of the brachial plexus bifurcates into what 2 nerves?
radial nerve and axillary nerve
Axillary nerves arises from which spinal cord segments?
C5 and C6
How does avulsion of roots C5 and C6 typically occur in adults and newborns? How is an affected upper extremity positioned after the onset of ErbDuchenne palsy?
In adults, shoulder hits something and stop while the head and trunk continue to move, leading to an excessive increase in the angle between the neck and shoulder; in newborns, excessive stretching of the neck during delivery; after Erb-Duchenne palsy, upper limb with an adducted shoulder, medially rotated arm, and extended elbow due to paralysis of the deltoids, biceps, and brachialis
Lateral cord of brachial plexus generates what nerve and root of the median nerve?
lateral pectoral nerve, lateral root of the median nerve
Medial cord of brachial plexus generates what nerve and root of the median nerve?
medial pectoral nerve, medial root of the median nerve
Medial cord continues as what?
ulnar nerve
Musculocutaneous nerve, median nerve, its lateral and medial roots, and the ulnar nerve create the letter M over the axillary artery
Visualize the axillary deep to the ‘M’
Brachial artery supplies what muscles?
anterior arm; biceps, brachialis, coracobrachialis
Deep artery of the arm (profunda brachii) location and supplies?
first and largest branch of the brachial artery; accompanies the radial nerve along the radial groove of the humerus to supply the triceps
Brachial artery bifurcates where and into what arteries?
near the elbow, into the radial and ulnar arteries that supply the forearm and the hand
Anastomosis in the arm and elbow
collateral branches of the brachial and profunda brachii arteries amastomose with recurrent branches of the radial and ulnar arteries
Why is laceration or occlusion of the brachial artery proximal to the profunda brachii artery a surgical emergency?
because paralyis of muscles results from ischemia of the elbow and forearm within a few hours
Why can the brachial artery be blocked at any level distal to the deep artery of the arm without stopping blood flow to the forearm and hand?
because the arterial anastomoses around the elbow provide collateral circulation sufficient for the ulnar and radial arteries
What is the normal role of the collateral circulation around the elbow?
to allow blood to reach the forearm when flexion of the elbow compromises flow through the terminal part of the brachial artery
Capitulum and trochlea
capitulum = articulates with the cupshaped depression on the head of the radius, and is limited to the front and lower part of the bone; humeral trochlea = medial portion of the articular surface of the elbow joint which articulates with the trochlear notch on the ulna in the forearm
Lateral and medial epicondyles
at or above the condyle (round prominence at the end of a bone)
Coronoid and olecranon fossae
coronoid fossa (anterior); olecranon fossa (posterior)
What forms the trochlear notch of the ulna?
olecranon and coronoid process
Trochlear notch articulates with what?
articulates with the trochlea of the humerus
Radial head articulates with what?
articulates with the capitulum of the humerus
When the forearm is flexed, where does the coronoid process move to?
coronoid fossa (anterior of humerus)
When the forearm is extended, where does the olecranon move to?
olecarnon fossa (posterior of humerus)
Purpose of radial and ulnar collateral ligments
strengthen the lateral and medial sides of the capsule of the elbow joint
Anular ligament
encircles and holds the head of the radius against the ulna; supports the proximal radioulnar joint that enables supination and pronation of the forearm and hand
How does posterior dislocation of the elbow joint typically occur and why is the distal humerus driven anteriorly? Which nerve may be damaged?
blow that drives the ulna posterior (fall on their hands with their elbows flexed), distal end of humerus is dirven through the weak anterior part of the fibrous layer of the joint capsule; ulnar nerve may be injuried
What is the most common cause of subluxation of the radial head in preschool children? Which ligament is commonly damaged and how is the injury treated?
child is suddenly lifted (jerked) by the upper limb while the forearm is pronated (lifting a child); tears the distal attachment of the anular ligament; treat by supination of the child’s forearm while the elbow the flexed, 2 weeks for anular ligament to heal
