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Questions and Answers
What is the main contributor to the deep palmar arch?
Which artery anastomoses with the anterior ulnar recurrent artery?
What is the primary function of the posterior divisions of the brachial plexus?
Which nerve originates from the medial cord and innervates the hand intrinsics?
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Which group of axillary lymph nodes is responsible for receiving lymph from the scapular area?
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Which nerve is responsible for the motor innervation of the serratus anterior muscle?
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What is the anatomical relationship of the axillary veins to the brachial plexus?
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Which branch of the medial cord innervates the pectoralis major muscle?
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Which artery is associated with the radial recurrent artery?
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Which terminal branch of the brachial plexus innervates the deltoid muscle?
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Which structure forms the anterior wall of the axillary region?
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What artery is a branch of the second part of the axillary artery?
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Which artery primarily supplies blood to the scapular muscles?
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What is the location of the axillary fossa?
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Which nerve structure is a crucial component of the contents of the axilla?
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Which two structures bound the apex of the axillary region?
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Which artery is not a branch of the third part of the axillary artery?
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From which artery does the suprascapular artery originate?
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What muscle forms the posterior wall of the axilla?
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What defines the lateral wall of the axillary region?
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What is the path of the anterior interosseous nerve in relation to the forearm flexors?
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Where does the ulnar nerve pass in relation to the flexor carpi ulnaris?
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Which nerve branches before passing through the carpal tunnel?
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What is the relationship between the ulnar nerve and the ulnar artery?
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Which nerve innervates muscles associated with the upper trunk?
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What is true about the median nerve in the distal forearm?
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Which nerve branches from the medial cord of the brachial plexus?
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Through which anatomical structure does the ulnar nerve pass at the wrist?
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What is the primary function of the musculocutaneous nerve?
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Which nerve corresponds to the C5 spinal nerve?
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Study Notes
Axilla
- The axilla is a pyramidal space, also known as the armpit, located between the arm and the body.
- It is defined by five boundaries: anterior, posterior, medial, lateral, and apex.
- The apex connects the axilla to the neck, allowing for the passage of important structures, including arteries, veins, nerves, and lymphatics.
Blood Supply
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Axillary Artery: This is the main artery supplying the upper limb, starting at the outer border of the first rib and running through the axilla.
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First Part: Medial to the pectoralis minor muscle.
- Supplies the superior/supreme thoracic artery.
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Second Part: Deep to the pectoralis minor muscle.
- Supplies the thoracoacromial trunk, which further branches into the deltoid, clavicular, acromial, and pectoral arteries.
- Supplies the lateral thoracic artery.
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Third Part: Lateral to the pectoralis minor muscle.
- Supplies the subscapular artery, which bifurcates into the circumflex scapular artery.
- Supplies the anterior circumflex humeral artery and the posterior circumflex humeral artery.
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First Part: Medial to the pectoralis minor muscle.
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Brachial Artery: Continuation of the axillary artery, starting at the inferior border of teres major muscle and continuing down the arm.
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Profunda (Deep) Brachial Artery: Travels in the spiral groove with the radial nerve.
- Supplies the deltoid branch.
- Supplies the middle collateral artery and radial collateral artery.
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Brachial Artery Branches: Branches into the radial and ulnar arteries distal to the elbow.
- The radial artery supplies multiple branches, including radial recurrent, carpal, deep palmar arch, and contributes to the superficial palmar arch.
- The ulnar artery also provides branches including anterior and posterior ulnar recurrent, common interosseous (which further branches into anterior and posterior interosseous), and contributes to the superficial and deep palmar arches.
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Profunda (Deep) Brachial Artery: Travels in the spiral groove with the radial nerve.
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Blood Supply to Scapular Muscles: These muscles receive their blood supply from various sources.
- Suprascapular artery (from the subclavian artery).
- Transverse cervical artery and descending scapular artery (from the subclavian artery).
- Subscapular artery (from the axillary artery).
- Posterior intercostal arteries (from the thoracic aorta).
Venous Drainage of the Upper Extremity
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Axillary Vein:
- Located superficial to the axillary artery and brachial plexus.
- Formed by the junction of the brachial veins and the basilic vein.
- The cephalic vein joins the axillary vein near the pectoralis minor muscle.
- Other tributaries correspond to the branches of the axillary artery.
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Venous Drainage of the Forearm:
- Deep veins: Correspond to the arteries.
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Superficial veins: Include:
- Dorsal venous network of the hand.
- Cephalic vein.
- Basilic vein.
- Median cubital vein.
Axillary Lymph Nodes
- These lymph nodes are organized in five groups at different locations within the axilla.
- Pectoral (Anterior) Group: Receives lymph from the pectoral muscles and breast.
- Subscapular (Posterior) Group: Receives lymph from the scapular area.
- Humeral (Lateral) Group: Receives lymph from the upper extremity.
- Central Group: Receives lymph from anterior, posterior, and lateral nodes.
- Apical Group: Receives lymph from the central group and drains to the subclavian nodes, right lymphatic duct, or thoracic duct.
Brachial Plexus
- This is a network of peripheral nerves arising from the ventral rami of spinal nerves C5-C8 and T1 that innervates structures of the upper limb and shoulder girdle.
- It comprises a series of interconnected structures: roots, trunks, divisions, cords, and branches.
- The various components are organized in a specific order, which can be remembered using the mnemonic "Randy Travis Drinks Cold Beer."
Branches directly from cervical ventral rami
- Dorsal Scapular (C4-C5): Innervates the rhomboids (C4 and C5) and the levator scapulae (C5).
- Long Thoracic (C5-C7): Innervates the serratus anterior(C5, C6, C7).
Trunks formed by spinal nerve roots
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Superior (C5-C6):
- Gives rise to the suprascapular nerve, which innervates the supraspinatus (C4-C6) and infraspinatus (C5-C6).
- Gives rise to the subclavius nerve (C5-C6).
- Middle (C7):
- Inferior (C8-T1):
Divisions
- Each trunk divides into an anterior and posterior division.
- Anterior divisions predominantly innervate flexors.
- Posterior divisions primarily innervate extensors.
Cords
- Posterior Cord: Formed by the posterior divisions of all three trunks.
- Lateral Cord: Formed by the anterior divisions of the superior and middle trunks.
- Medial Cord: Formed by the anterior division of the inferior trunk.
Branches
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Lateral Cord:
- Lateral Pectoral Nerve: (C5-C7): Innervates the pectoralis major (clavicular part).
- Musculocutaneous Nerve: (C5-C7): Innervates the anterior arm muscles.
- Lateral Root of Median Nerve: (C6-C7): Innervates the forearm flexors and hand intrinsics.
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Medial Cord:
- Medial Pectoral Nerve: (C8-T1): Innervates the pectoralis major (sternocostal part) and pectoralis minor.
- Medial Cutaneous Nerve to the Arm: (C8-T1):
- Medial Cutaneous Nerve to the Forearm: (C8-T1):
- Ulnar Nerve: (C8-T1; may receive some C7): Innervates the 1 1/2 forearm muscles and hand intrinsics.
- Medial Root of Median Nerve: (C8-T1): Innervates forearm flexors and hand intrinsics.
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Posterior Cord:
- Upper Subscapular Nerve: (C5): Innervates the subscapularis.
- Thoracodorsal Nerve: (C6, C7, C8): Innervates the latissimus dorsi.
- Lower Subscapular Nerve: (C6): Innervates the subscapularis and teres major muscles.
- Axillary Nerve: (C5, C6): Innervates the deltoid and teres minor.
- Radial Nerve: (C5-T1): Innervates the extensors of the arm and forearm, as well as the brachioradialis.
Another Way to Look at it
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Supraclavicular Branches:
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From Roots:
- Dorsal Scapular: Innervates the rhomboids and levator scapulae.
- Long Thoracic: Innervates the serratus anterior.
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From Trunks:
- Suprascapular Nerve: Innervates the supraspinatus and infraspinatus.
- Nerve to Subclavius (Subclavian Nerve): Innervates the subclavius.
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From Roots:
- Infraclavicular Branches: (from cords): Refer to the list of Branches above
Cutaneous Distribution
- Peripheral nerve Distribution:
- Dermatomal Distribution:
Courses of the Major Terminal Branches Through the Arm and Forearm
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Radial:
- Travels through the spiral groove with the profunda brachial artery.
- Passes between the brachialis and brachioradialis muscles.
- At the elbow, it divides into the superficial and deep radial nerves:
- Superficial Radial Nerve: Provides cutaneous innervation to the posterior forearm and lateral posterior hand.
- Deep Radial Nerve: Becomes the posterior interosseus nerve distal to the supinator, and innervates the forearm extensors.
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Median:
- Travels with the brachial artery along the medial arm.
- Passes through the cubital fossa anterior to the elbow joint.
- Travels between the heads of the pronator teres.
- Gives rise to the anterior interosseus nerve which travels deep to the forearm flexors.
- Travels deep to the flexor digitorum superficialis, superficial to the profundus.
- Continues deep to the palmaris longus in the distal forearm.
- Passes through the carpal tunnel.
- Provides cutaneous branches to the palm and palmar digital nerves.
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Ulnar:
- Travels along the medial arm with the brachial artery.
- Passes through the cubital tunnel, a groove behind the medial epicondyle.
- Passes between the two heads of the flexor carpi ulnaris.
- Travels with the ulnar artery just deep to the flexor carpi ulnaris (FCU).
- Travels through the tunnel of Guyon on the anterior medial wrist.
Brachial Plexus Schematic
- A schematic diagram should show the relevant nerves, their origin, branching, and distribution.
- Roots: Dorsal Scapular (C5), Suprascapular (C6), Long Thoracic (C5-C7), Upper (C5-C6), Middle (C7), Inferior (C8-T1).
- Trunks: Superior (C5-C6), Middle (C7), Inferior (C8-T1).
- Cords: Lateral, Medial, Posterior.
- Branches: Lateral Pectoral, Musculocutaneous, Lateral Root of Median, Medial Pectoral, Medial Cutaneous Nerve to Forearm, Medial Cutaneous Nerve to Arm, Ulnar, Medial Root of Median, Upper Subscapular, Thoracodorsal, Lower Subscapular, Axillary, Radial.
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Description
Explore the intricate details of the axilla, a crucial anatomical space located between the arm and the body. This quiz covers its boundaries, structures, and the blood supply provided by the axillary artery. Test your knowledge on the significant vascular anatomy in this region.
