4: Anatomy Of Axilla & Arm Flashcards
Cervico-axillary canal is bounded:
A. Infront by?
B. Posteriorly by?
C. Medially by?
A. Clavicle
B. upper border of the scapula
C. first rib
The brachial plexus and axillary artery enter the axilla through this canal. The axillary vein and lymphatics enter the neck through this canal.
Cervicoaxillary canal
What muscle is found infront of axilla forming anterior axillary fold?
Pectoralis major (it’s inserted in lateral lib of bicipital groove)
Two muscles found behind the axilla forming posterior axillary fold?
Lattisimus dorsi & teres major
What muscles form Anterior wall of axilla?
Pectoralis major, pectoralis minor and subclavius muscles.
What muscles form posterior wall of axilla?
Subscapularis, latissimus dorsi and teres major muscles.
What form medial wall of axilla?
Upper four intercostal spaces (upper thoracic wall) with upper part of the serratus anterior muscle.
What muscles form lateral wall of axilla?
Shaft of the humerus with coracobrachialis and short head of the biceps brachii muscle and also long head of the biceps brachii in the intertubercular sulcus.
What structures are enclosed by axillary sheath?
Brachial plexus + axillary artery are enclosed with axillary sheath providing protection (axillary vein is outside)
This vein pierces the clavipectoral fascia and drains into axillary vein. It runs in deltopectoral groove.
Cephalic vein
This nerve is the Lateral cutaneous branch of 2nd intercostal nerve comes and supply the skin of armpit. (Brings T2 supply)
Intercostobrachial nerve
Name the artery:
A. Before 1st rib:
B. After first rib:
C. After teres major:
A. Subclavian A.
B. Axillary A.
C. Brachial A.
This muscle divided the Axillary artery into 3 parts
Pectoralis minor
It divides the axillary into 3 parts:
◦Proximal or before the muscle is 1st part
◦Deep to muscle or posterior to it is 2nd part
◦Distal to muscle is the 3rd part
The 1st part of axillary gives a branch called …?
Superior thoracic A.
The second part of axillary gives two branches these are…?
Thoracoacromial A. & Lateral thoracic A.
The 3rd part of axillary gives 3 branches these are:
Anterior and posterior circumflex humeral arteries and subscapular artery
if there is downward dislocation of the shoulder joint.
A. what nerve is likely to be injured?
B. What muscles will be paralyzed?
A. Axillary Nerve
B. Deltoid & teres minor
How to test if axillary N. is injured?
Skin over deltoid is supplied by Axillary nerve, so we can test the sesation at the area through a pin brick (test skin sensation superolaterally)
There are anastomoses between branches of circumflex scapular and suprascapular artery. What does the anastomoses connect?
It connects 1st part of subclavian with 3rd part of axillary artery
What gives rise to a clinical sign called ‘pulsating scapula’ ?
In case of obstruction in distal part of the subclavian artery or proximal part of the axillary artery these anastomotic vessels enlarge considerable to provide collateral circulation. This may give rise to a clinical sign called ‘pulsating scapula’.
What nerve pierces coracobrachialis?
Musculocutaneous nerve
patient had surgery for removal of axillary LN, he complains of numbness or lack of sensation in armpit. Which nerve is affected?
Intercostobrachial Nerve
Biceps brachii (origin of short and long heads)
- Short head → Tip of the coracoid process along with coracobrachialis
- Long head→ Supraglenoid tubercle of the scapula within the shoulder joint cavity.
Insertion of biceps brachii?
Tuberosity of radius
Nerve supply of biceps brachii?
Musculocutaneous nerve.
Action of biceps brachii
It supinates the forearm at the radioulnar joint and flexes the elbow joint. It is also a weak flexor of the shoulder joint. The long head stabilizes the head of the humerus during shoulder movements.
Brachialis (origin & insertion)
- Origin: It arises from the lower part of the shaft of the humerus. It descends in front of the elbow joint forming the floor of the cubital fossa.
- insertion: ulnar tuberosity
Coracobrachialis (origin & insertion)
- Origin: It takes origin from the tip of the coracoid process of the scapula along with the short head of the biceps brachii muscle
- Insertion: It is inserted into the middle of medial surface of the humerus.
What nerve supplies the skin in front and back of the forearm
along the lateral side? Where does it arise from?
Lateral cutaneous N. / Musculocutaneous N.
(It arises from the lateral cord of the brachial plexus)
Triceps brachii (origin of the 3 heads)
- Long head → Infraglenoid tubercle of the scapula
- Lateral head → A ridge above the radial groove of the humerus
- Medial head → Posterior surface of the humerus below the radial groove.
Radial nerve branches (muscular & cutaneous)
Brachial artery (origin, termination, branches)
A 9-year-old boy fell off a swing and sustained a supracondylar fracture of his left humerus. Following the reduction of the fracture, a plaster cast was applied, and the child was sent home. Few hours later, the child complained of pain in the forearm, which aggravated. The child’s left hand looked darkish white, and the pain in forearm was still present. On examination, it was found that the cutaneous sensation of the hand was completely lost. The colour of the skin was bluish white. The lower part of the plaster cast was removed but pulse of the radial and the ulnar arteries could not be palpated.
شنو المشكلة؟
Volkmann’s ischemic contracture
Apical group of axillary LN goes out as lymphatic vessel called …?
subclavian lymphatic vessel
((Go through slide))
Anterior & posterior compartments of arm (muscle, blood supply, nerve)
Nerves of the Axilla and their distribution (slide attached)
