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Questions and Answers
Which nerve is vulnerable to injury during anterior shoulder dislocation?
Which nerve is vulnerable to injury during anterior shoulder dislocation?
What action does the deltoid muscle's anterior fibers perform?
What action does the deltoid muscle's anterior fibers perform?
Which muscle is responsible for abducting the arm and is innervated by the suprascapular nerve?
Which muscle is responsible for abducting the arm and is innervated by the suprascapular nerve?
What is the primary action of the subscapularis muscle?
What is the primary action of the subscapularis muscle?
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Which two muscles are classified as external rotators of the arm?
Which two muscles are classified as external rotators of the arm?
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Which part of the humerus articulates with the glenoid cavity of the scapula?
Which part of the humerus articulates with the glenoid cavity of the scapula?
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What action does the teres major muscle perform?
What action does the teres major muscle perform?
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Which of the following nerves innervates the teres minor muscle?
Which of the following nerves innervates the teres minor muscle?
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What is the primary function of the clavicle in the upper extremities?
What is the primary function of the clavicle in the upper extremities?
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Which joint is classified as a synovial ball-and-socket joint?
Which joint is classified as a synovial ball-and-socket joint?
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Which artery supplies the skin over the deltoid region?
Which artery supplies the skin over the deltoid region?
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Which type of joint is characterized by articulating surfaces enclosed within a fluid-filled capsule?
Which type of joint is characterized by articulating surfaces enclosed within a fluid-filled capsule?
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Which ligament extends between the coracoid process and the acromion?
Which ligament extends between the coracoid process and the acromion?
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What feature of the scapula can be easily palpated?
What feature of the scapula can be easily palpated?
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The medial two thirds of the clavicle has which shape?
The medial two thirds of the clavicle has which shape?
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Which ligaments help to stabilize the shoulder joint?
Which ligaments help to stabilize the shoulder joint?
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Which muscle is responsible for elbow flexion?
Which muscle is responsible for elbow flexion?
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What is the origin of the long head of the biceps brachii?
What is the origin of the long head of the biceps brachii?
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Which nerve supplies the anterior compartment of the arm?
Which nerve supplies the anterior compartment of the arm?
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What is the action of the coracobrachialis muscle?
What is the action of the coracobrachialis muscle?
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Which artery marks the beginning of the brachial artery?
Which artery marks the beginning of the brachial artery?
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What is the insertion point for the triceps muscle?
What is the insertion point for the triceps muscle?
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Which statement about the elbow joint is true?
Which statement about the elbow joint is true?
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Which part of the brachial plexus is formed by the union of C5 and C6 roots?
Which part of the brachial plexus is formed by the union of C5 and C6 roots?
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Study Notes
Cutaneous Innervation
- Supraclavicular artery supplies skin over the lateral end of the clavicle.
- Anterior and posterior circumflex humeral arteries provide sensory innervation to the deltoid region.
- Musculocutaneous and fasciocutaneous perforators supply the upper arm skin.
Clavicle
- Articulates medially with the sternum and 1st costal cartilage and laterally with the scapula's acromion process.
- Serves as a strut holding the arm away from the trunk.
- Medial two-thirds of the clavicle is convex; lateral third is concave.
Sternoclavicular Joint
- A synovial plane joint formed between the sternal end of the clavicle and the manubrium sterni.
- Joint capsule surrounds the joint, attached to the articular surface margins.
Classification of Joints
- Fibrous Joints: Bones connected by fibrous tissue.
- Cartilaginous Joints: Bones connected by cartilage.
- Synovial Joints: Enclosed within a fluid-filled joint capsule, most common joint type, allowing free movement.
Scapula
- A flat triangular bone located between the 2nd and 7th ribs on the posterior chest wall.
- The inferior angle aligns with the 7th rib and the spinous process of the 7th thoracic vertebra.
Glenohumeral Joint
- A synovial ball-and-socket joint between the humerus's head and the scapula's glenoid cavity.
- Joint capsule is thin, allowing extensive movement, strengthened by rotator cuff tendons.
Shoulder Ligaments
- Glenohumeral Ligaments: Three weak bands frontally strengthen the capsule.
- Transverse Humeral Ligament: Bridges the gap between tuberosities.
- Coracohumeral Ligament: Strengthens the upper capsule from the coracoid process to the humerus.
- Coracoacromial Ligament: Protects the superior joint aspect.
Shoulder Dislocation
- Most commonly dislocated joint; anterior dislocation is more prevalent than posterior.
- Axillary nerve at risk during anterior dislocation.
Muscles Connecting Scapula to Humerus
- Deltoid: Originates from the clavicle, acromion, and scapula spine; action includes arm flexion, abduction, and extension; innervated by the axillary nerve.
- Supraspinatus: Abducts the arm; innervated by the suprascapular nerve.
- Infraspinatus: Externally rotates the arm; innervated by the suprascapular nerve.
- Teres Minor: Also externally rotates the arm; innervated by the axillary nerve.
- Subscapularis: Internal rotation of the arm; innervated by the subscapular nerve.
- Teres Major: Adduction and internal rotation of the arm; innervated by subscapular nerve.
Rotator Cuff Muscles
- Comprises the supraspinatus, infraspinatus, and teres minor for external rotation and subscapularis for internal rotation.
Humerus
- Articulates with the scapula at the shoulder and with the radius/ulna at the elbow.
- Features include the head (at the shoulder), capitulum (for the radius), and trochlea (for the ulna).
Fascial Compartment of the Arm
- Anterior Compartment: Contains the biceps brachii (elbow flexor and forearm supinator), coracobrachialis (flexes arm), and brachialis (elbow flexor); all innervated by the musculocutaneous nerve.
- Posterior Compartment: Contains the triceps brachii for elbow extension, innervated by the radial nerve.
Elbow Joint
- A synovial hinge joint formed by the trochlea and capitulum of the humerus articulating with the ulna's trochlear notch and the head of the radius.
Blood Supply and Nerve Supply
- Axillary Artery: Begins at the 1st rib's lateral border and transitions into the brachial artery at the teres major's lower border.
- Brachial Artery: Supplies arm and divides into radial and ulnar arteries near the radius neck.
- Brachial Plexus: Comprises roots from C5-T1 spinal nerves; classified into roots, trunks, divisions, and cords, providing nerve supply to the upper limb.
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