Upper limb muscles

Question 1

Pectoralis Major

Answer 1

Origin: Sternum, superior 6 costal cartilages, clavicle.
Insertion: Lateral lip of bicipital groove of humerus.
Function: Adducts and medially rotates the humerus, assists in arm flexion.
Innervation: Lateral and medial pectoral nerves.

Question 2

Deltoid

Answer 2

Origin: Clavicle (anterior fibers), spine of scapula (posterior fibers), acromion (middle fibers).
Insertion: Deltoid tuberosity of humerus.
Function: Anterior fibers flex and medially rotate the arm; middle fibers abduct the arm; posterior fibers extend and laterally rotate the arm.
Innervation: Axillary nerve (C5, C6).

Question 3

Supraspinatus

Answer 3

Origin: Supraspinous fossa of scapula.
Insertion: Greater tubercle of humerus.
Function: Assists deltoid in arm abduction.
Innervation: Suprascapular nerve (C4, C5, C6).

Question 4

Infraspinatus

Answer 4

Origin: Infraspinous fossa of scapula.
Insertion: Posterior aspect of greater tubercle of humerus.
Function: Laterally rotates the arm.
Innervation: Suprascapular nerve (C5, C6).

Question 5

Subscapularis

Answer 5

Origin: Subscapular fossa of scapula.
Insertion: Lesser tubercle of humerus.
Function: Medially rotates and adducts the arm.
Innervation: Subscapular nerves (C5, C6, C7).

Question 6

Serratus Anterior

Answer 6

Origin: Lateral surfaces of the 1st-8th ribs.
Insertion: Superior and inferior angles, medial border of scapula.
Function: Rotates scapula anterolaterally, protracts and upwardly rotates the scapula.
Innervation: Long thoracic nerve (C5, C6, C7).

Question 7

Biceps Brachii

Answer 7

Origin: Long head - supraglenoid tubercle; short head - coracoid process of scapula.
Insertion: Radial tuberosity and bicipital aponeurosis.
Function: Flexes the forearm at the elbow, powerful supinator of the forearm.
Innervation: Musculocutaneous nerve.

Question 8

Flexor Carpi Ulnaris

Answer 8

Origin: Medial epicondyle of humerus, olecranon of ulna.
Insertion: Pisiform, hook of hamate, and 5th metacarpal bone.
Function: Flexes and adducts the wrist.
Innervation: Ulnar nerve.

Question 9

Triceps Brachii

Answer 9

Origin: Long head - infraglenoid tubercle; lateral and medial heads - posterior humerus.
Insertion: Olecranon of the ulna.
Function: Main extensor of the elbow joint.
Innervation: Radial nerve.

Question 10

Flexor Digitorum Superficialis

Answer 10

Origin: Medial epicondyle of humerus, coronoid process of ulna, superior half of radius.
Insertion: Middle phalanges of the 4 medial digits.
Function: Flexes middle and proximal phalanges.
Innervation: Median nerve.

Question 11

Flexor Digitorum Profundus

Answer 11

Origin: Ulna and interosseous membrane.
Insertion: Base of distal phalanges of medial 4 digits.
Function: Flexes distal interphalangeal joints of the medial 4 digits.
Innervation: Medial half - ulnar nerve; lateral half - median nerve.

Question 12

Supinator

Answer 12

Origin: Lateral epicondyle of humerus, radial collateral and annular ligaments, supinator fossa, and crest of ulna.
Insertion: Lateral, posterior, and anterior surfaces of the proximal third of the radius.
Function: Supinates the forearm.
Innervation: Deep branch of the radial nerve.

Question 12

Extensor Carpi Radialis Longus

Answer 12

Origin: Lateral supracondylar ridge of humerus.
Insertion: Base of 2nd metacarpal.
Function: Extends and abducts the wrist.
Innervation: Radial nerve.

Question 13

Extensor Digitorum

Answer 13

Origin: Lateral epicondyle of humerus.
Insertion: Extensor expansions of medial 4 digits.
Function: Extends proximal phalanges and hand at wrist joint.
Innervation: Radial nerve.

Question 14

Anatomical Snuff Box

Answer 14

Boundaries: Abductor pollicis longus (APL) and extensor pollicis brevis (EPB) anteriorly, extensor pollicis longus (EPL) posteriorly.
Contents: Radial artery, scaphoid, and trapezium bones.
Clinical Relevance: Tenderness in this area may indicate a scaphoid fracture.