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Questions and Answers
Which of the following nerves arises from the medial cord of the brachial plexus?
Which of the following nerves arises from the medial cord of the brachial plexus?
What is the anatomical position of the lateral cord of the brachial plexus in relation to the second part of the axillary artery?
What is the anatomical position of the lateral cord of the brachial plexus in relation to the second part of the axillary artery?
Which roots contribute to the long thoracic nerve?
Which roots contribute to the long thoracic nerve?
The medial cord of the brachial plexus has contributions from which spinal nerves?
The medial cord of the brachial plexus has contributions from which spinal nerves?
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What is the primary function of the dorsal scapular nerve?
What is the primary function of the dorsal scapular nerve?
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Which nerve serves as the main blood supply to the upper limb, starting from the subclavian artery?
Which nerve serves as the main blood supply to the upper limb, starting from the subclavian artery?
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Which of the following statements about the posterior cord of the brachial plexus is true?
Which of the following statements about the posterior cord of the brachial plexus is true?
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Which branch of the brachial plexus is primarily responsible for innervating the thoraco-dorsal region?
Which branch of the brachial plexus is primarily responsible for innervating the thoraco-dorsal region?
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Which nerve, originating from the posterior cord of the brachial plexus, innervates the deltoid muscle?
Which nerve, originating from the posterior cord of the brachial plexus, innervates the deltoid muscle?
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What action is primarily performed by the supraspinatus muscle?
What action is primarily performed by the supraspinatus muscle?
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Which artery passes posterior to the surgical neck of the humerus?
Which artery passes posterior to the surgical neck of the humerus?
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The paralysis of the serratus anterior muscle is likely due to damage of which nerve?
The paralysis of the serratus anterior muscle is likely due to damage of which nerve?
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Which muscles are innervated by the axillary nerve?
Which muscles are innervated by the axillary nerve?
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What is the main action of the teres major muscle?
What is the main action of the teres major muscle?
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Which nerve provides sensation to the skin over the deltoid muscle?
Which nerve provides sensation to the skin over the deltoid muscle?
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Which structure forms the boundaries of the posterior quadrangular space?
Which structure forms the boundaries of the posterior quadrangular space?
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Which structure is NOT a component of the axilla?
Which structure is NOT a component of the axilla?
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What is the primary function of the brachial plexus?
What is the primary function of the brachial plexus?
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Which of the following correctly describes the organization of the brachial plexus?
Which of the following correctly describes the organization of the brachial plexus?
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Which root of the brachial plexus does NOT contribute to the formation of the superior trunk?
Which root of the brachial plexus does NOT contribute to the formation of the superior trunk?
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How many anterior and posterior divisions does each trunk of the brachial plexus divide into?
How many anterior and posterior divisions does each trunk of the brachial plexus divide into?
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What is the role of the terminal branches of the brachial plexus?
What is the role of the terminal branches of the brachial plexus?
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Which of the following statements about the axillary inlet is true?
Which of the following statements about the axillary inlet is true?
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Which root of the brachial plexus is derived from the highest spinal nerve?
Which root of the brachial plexus is derived from the highest spinal nerve?
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Study Notes
Axilla & Brachial Plexus
- The axilla is the gateway to the upper limb, acting as a transition zone between the neck and arm.
- It's shaped like a pyramid with four walls, an inlet (apex), and a base.
- The axillary inlet connects to the neck superiorly.
- Its borders include the clavicle anteriorly, the scapula posteriorly, and the first rib medially.
- The floor of the axilla is formed by the skin of the armpit.
Contents of the Axilla
- Brachial plexus: a network of nerves controlling upper limb function.
- Axillary artery: the main blood vessel supplying the upper limb.
- Axillary vein: a major vein draining blood from the upper limb.
- Axillary lymph nodes: crucial for immune function in the region.
- Tail of the breast in females: a portion of breast tissue extending into the axilla.
Brachial Plexus Formation
- The brachial plexus is composed of the anterior rami of spinal nerves C5, C6, C7, C8, and most of T1.
- It has five stages, beginning with roots in the neck, then passing trunks behind the clavicle
- Following the trunks, divisions form, then cords in the axilla.
- Finally, terminal branches emerge, creating nerves that innervate various muscles and functions of the upper limb.
Brachial Plexus Cords
- Three cords, the lateral, medial, and posterior cords, emerge from the divisions of the brachial plexus.
- Each cord is associated with specific branches.
- The lateral cord contains the lateral pectoral nerve, musculocutaneous nerve, and lateral root of the median nerve.
- The medial cord contains the medial pectoral nerve, medial cutaneous nerve of the forearm, medial root of median nerve, and ulnar nerve.
- The posterior cord contains the upper and lower subscapular nerves, nerve to latissimus dorsi, radial nerve and the axillary nerve.
Axillary Nerve
- Originating from the posterior cord of the brachial plexus:
- It passes through the quadrangular space, entering the posterior scapular region
- Provides sensation from the skin over the deltoid muscle and also innervates the deltoid and teres minor muscles.
Axillary Artery
- The main artery supplying the upper limb.
- Begins at the lateral border of the first rib.
- Becomes the brachial artery at the lower border of the teres major muscle.
- Branches: anterior and posterior circumflex humeral arteries.
Scapular Region Muscles
- Supraspinatus: Initiates abduction (0-15°) of the shoulder, supplies nerves by suprascapular nerve.
- Infraspinatus: Lateral rotation at the shoulder, supplies nerves by suprascapular nerve.
- Teres minor: Lateral rotation at the shoulder, supplied by the axillary nerve.
- Teres major: Medial rotation, extension, and adduction of the shoulder, supplied by the lower subscapular nerve.
- Subscapularis: Medial rotation at the shoulder, supplied by the upper and lower subscapular nerves.
- Deltoid: Flexion, extension, and abduction of the shoulder; supplied by the axillary nerve.
Other muscles of the back and their nerve supply and actions
- Trapezius: Elevation and depression of the shoulder. Spinal accessory nerve.
- Levator scapulae: Elevation of the shoulder. Dorsal scapular nerve.
- Rhomboid major and minor: Retraction of the scapula. Dorsal scapular nerve.
- Latissimus dorsi: Extends and medially rotates the humerus. Thoracodorsal nerve.
Spaces of the Scapular Region
- Posterior Quadrangular Space: Contains the axillary nerve.
- Upper Triangular Space: Contains the suprascapular nerve.
- Lower Triangular Space: Contains the radial nerve.
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Description
Test your understanding of the axilla and brachial plexus with this comprehensive quiz. Explore the structures, functions, and anatomical significance of this critical area connecting the neck and upper limb. Perfect for students of anatomy and medical professionals alike.
