Lab 4: Pectoral Region Flashcards
Most frequently fractured bone in region
Clavicle, usually in middle and lateral 1/3 of clavicle (where there are fewer muscles/tendon attachments)
Significance of the scapular circumflex artery
Joins the dorsal scapular and suprascapular arteries (arterial anastomoses around scapula). Allows for surgical ligation of axillary artery proximal to subscapular.
Nerve & Artery passing through Quadrangular Space
Axillary nerve and posterior circumflex humeral artery. The axillary nerve is at risk of being damaged from a fracture to the surgical neck of humerus.
Erb-Duchenne Palsy
Results in characteristic “waiter’s tip posture” (arm adduction and medially rotated/pronated, palm facing back. Results from injury to upper brachial plexus (anterior rami of C5, C6). Commonly caused when motorcyclists are thrown from one side of head or when baby’s head is pulled during delivery
Klumpke’s Paralysis
Caused by injury to C8, T1 (lower part of brachial plexus). Usually caused when baby’s upper limb is pulled strongly upward during delivery. Results in paralysis of intrinsic hand muscles, “claw hand” deformity.
Injury to long thoracic nerve
Vulnerable to trauma and axilla surgery. Damage leads to winging of the scapula, inability to raise arm above horizontal plane
Rotator Cuff Muscles
Dynamic stabilizers to the glenohumeral joint. Made up of supraspinatus, infraspinatus, teres minor and subclavius muscles. Injury to RTC causes painful & debilitating injury.
At what point does the axillary become the brachial artery?
The axillary artery continues as the brachial artery after passing the inferior border of the teres major
Branches of the axillary artery
(proximal to distal): superior thoracic artery, thoracoacromial artery (4 branches), lateral thoracic artery, suprascapular artery (2 branches), anterior circumflex humeral artery, posterior circumflex humeral artery
What does the thoracoacromial artery branch off into?
(lateral) : clavicular, acromial and deltoid branches.
(medial) : pectoral branch
What does the subscapular artery branch off into?
Thoracodorsal and circumflex scapular artery
Nerves from C5, C6 (brachial plexus)
Upper portion of brachial plexus. C5 & C6 converge to innervate the suprascapular nerve, lateral pectoral nerve, musculocutaneous nerve. Converges to also supply median nerve, radial and axillary nerve. Only C5 branches off to supply dorsal scapular nerve
Nerves from C7 (brachial plexus)
Radial and axillary nerves, subscapular nerves (upper scapular, lower scapular, middle known as thoracodorsal nerve), musculotaneous nerve
Nerves from C8, T1 (brachial plexus)
Ulnar nerve, medial pectoral nerve, medial brachial nerve, medial antebrachial nerve, median nerve.
Subclavius
Functions to anchor and depress the clavicle. Innervated by subclavian nerve (C5, C6)
Winged Scapula
Caused by injury to long thoracic nerve, which innervates the serratus anterior. Results in winging of scapula and difficulty abducting arm above 90 degrees (horizontal)
Subclavian Artery
Turns into axillary artery after passing lateral border of first rib (axillary -> brachial artery). Can be used to control bleeding from the axillary or brachial artery (and/or branches). Used to administer fluids, medications
Axilla
Pyramidal space that provides a gateway for major blood vessels and nerves
Superior and Inferior Borders of Axilla
Apex: clavicle, superior border of scapula
Base: Skin, subcutaneous tissue, axillary fascia (together form armpit)
Walls of Axilla
Medial wall: thoracic wall, serratus anterior
Lateral wall: intertubercular groove of humerus
Anterior wall: pectoralis major/minor, pectoral fascia
Poterior wall: scapula, teres major, latissimus dorsi, subscapularis
Axillary artery branches
1st part: superior thoracic a.
2nd part: thoracoacromial a. + lateral thoracic a.
3rd part: subscapular a. + anterior circumflex humeral a. + posterior circumflex humeral a.
Axillary vein
Continuation of the brachial vein. Branches into cephalic and basilic vein
Thoracic Outlet Syndrome
Lower brachial plexus lesion. Subdivided into:
- -Cervical rib syndrome
- -Scalenus anticus syndrome: anterior scalene muscle compresses plexus or subclavian artery
- -Costoclavicular syndrome: compression of clavicle b/n first rib and clavicle
Anterior interosseous nerve
Motor branch of the median nerve arising below the elbow and innervating deep muscles of anterior forearm. Injury to AIN can lead to anterior interosseous syndrome
Anterior Interosseous Syndrome
Injury to anterior interosseous nerve, resulting in weakness of thumb, index finger and pain in forearm. Leads to characteristic papal (benediction) sign when trying to flex fingers (only median nerve innervations affected)
