Upper limb muscles

Question 1

Trapezius

Answer 1

Attachments:
Originates from the skull, nuchal ligament and the spinous processes of C7-T12. The fibres attach to the clavicle, acromion, and the scapula spine.

Actions:
The upper fibres of the trapezius elevate the scapula and rotates it during abduction of the arm. The middle fibres retract the scapula and the lower fibres pull the scapula inferiorly.

Innervation:
Motor innervation is from the accessory nerve. It also receives proprioceptor fibres from C3 and C4 spinal nerves.

Blood supply:
Occipital artery (descending part), superficial or transverse cervical artery (transverse part), dorsal scapular artery (ascending part)

Question 2

Latissimus dorsi

Answer 2

Attachments:
Has a broad origin – arising from the spinous processes of T7-T12, iliac crest, thoracolumbar fascia and the inferior three ribs. The fibres converge into a tendon that attaches to the intertubercular sulcus of the humerus.

Actions:
Extends, adducts, and medially rotates the upper limb.

Innervation:
Thoracodorsal nerve.

Blood supply:
Thoracodorsal artery, perforating arteries of the 9th-11th posterior intercostal arteries, and 1st-3rd lumbar arteries

Question 3

Levator scapulae

Answer 3

Attachments:
Originates from the transverse processes of the C1-C4 vertebrae and attaches to the medial border of the scapula.

Actions:
Elevates the scapula.

Innervation: Dorsal scapular nerve.

Blood supply:
Transverse cervical and ascending cervical arteries (branches of the thyrocervical trunk)

Question 4

Rhomboid major

Answer 4

Attachments:
Originates from the spinous processes of T2-T5 vertebrae. Attaches to the medial border of the scapula, between the scapula spine and inferior angle.

Actions:
Retracts and rotates the scapula.

Innervation:
Dorsal scapular nerve

Blood supply:
Dorsal scapular artery, deep branch of transverse cervical artery, dorsal branch of upper five or six posterior intercostal arteries

Question 5

Rhomboid minor

Answer 5

Attachments:
Originates from the spinous processes of C7-T1 vertebrae. Attaches to the medial border of the scapula, at the level of the spine of scapula.

Actions:
Retracts and rotates the scapula.

Innervation:
Dorsal scapular nerve.

Blood supply:
Dorsal scapular artery, deep branch of transverse cervical artery, dorsal branch of upper five or six posterior intercostal arteries

Question 6

Biceps brachii

Answer 6

Attachments:
Long head originates from the supraglenoid tubercle of the scapula, and the short head originates from the coracoid process of the scapula. Both heads insert distally into the radial tuberosity and the fascia of the forearm via the bicipital aponeurosis.

Function:
Supination of the forearm. It also flexes the arm at the elbow and at the shoulder.

Innervation:
Musculocutaneous nerve. The bicep tendon reflex tests spinal cord segment C6.

Blood supply:
Branches of brachial artery

Question 7

Coracobrachialis

Answer 7

Attachments:
Originates from the coracoid process of the scapula. The muscle passes through the axilla, and attaches the medial side of the humeral shaft, at the level of the deltoid tubercle.

Function:
Flexion of the arm at the shoulder, and weak adduction.

Innervation:
Musculocutaneous nerve.

Blood supply:
Muscular branches of brachial artery

Question 8

Brachialis

Answer 8

Attachments:
Originates from the medial and lateral surfaces of the humeral shaft and inserts into the ulnar tuberosity, just distal to the elbow joint.

Function:
Flexion at the elbow.

Innervation:
Musculocutaneous nerve, with contributions from the radial nerve.

Blood supply:
Brachial artery, radial recurrent artery, (occasionally) branches from the superior and inferior ulnar collateral arteries

Question 9

Triceps Brachii

Answer 9

Attachments:
Long head – originates from the infraglenoid tubercle.Lateral head – originates from the humerus, superior to the radial groove. Medial head – originates from the humerus, inferior to the radial groove. Distally, the heads converge onto one tendon and insert into the olecranon of the ulna.

Function: Extension of the arm at the elbow.

Innervation: Radial nerve. A tap on the triceps tendon tests spinal segment C7.
(long head innervated by axillary in some)

Blood supply:
Deep brachial artery, superior ulnar collateral artery

Question 10

Flexor Carpi ulnaris (Superficial Compartment)

Answer 10

Attachments:
The flexor carpi ulnaris has two origins. The humeral head originates from the medial epicondyle of the humerus with the other superficial flexors, whilst the ulnar head originates from the olecranon of the ulna.
The muscle tendon passes into the wrist and attaches to the pisiform bone, hook of hamate, and base of the 5th metacarpal

Actions: Flexion and adduction at the wrist.

Innervation: Ulnar nerve.

Blood supply:
Posterior ulnar recurrent artery, ulnar artery

Question 11

Palmaris longus (Superficial Compartment)

Answer 11

Attachments:
Originates from the medial epicondyle, attaches to the flexor retinaculum of the wrist.

Actions:
Flexion at the wrist.

Innervation:
Median nerve.

Blood supply:
Anterior ulnar recurrent artery, median artery

Question 12

Flexor Carpi Radialis (Superficial Compartment)

Answer 12

Attachments:
Originates from the medial epicondyle, attaches to the base of metacarpals II and III.

Actions:
Flexion and abduction at the wrist.

Innervation:
Median nerve.

Blood supply:
Anterior/posterior recurrent ulnar artery, radial artery

Question 13

Pronator Teres (Superficial Compartment)

Answer 13

Attachments:
It has two origins, one from the medial epicondyle, and the other from the coronoid process of the ulna. It attaches laterally to the mid-shaft of the radius.

Actions:
Pronation of the forearm.

Innervation:
Median nerve.

Blood supply:
Branches of brachial, radial and ulnar arteries

Question 14

Flexor digitorum superficialis (only muscle of the intermediate compartment)

Answer 14

Attachments:
It has two heads – one originates from the medial epicondyle of the humerus, the other from the radius. The muscle splits into four tendons at the wrist, which travel through the carpal tunnel, and attach to the base of the middle phalanx of the four digits.

Actions:
Flexes the metacarpophalangeal joints and proximal interphalangeal joints at the 4 fingers, and flexes at the wrist.

Innervation:
Median nerve.

Blood supply:
Ulnar artery, radial artery, median artery

Question 15

Flexor Digitorum Profundus (Deep Compartment)

Answer 15

Attachments:
Originates from the ulna and associated interosseous membrane. At the wrist, it splits into four tendons, that pass through the carpal tunnel and attach to the distal phalanges of the four fingers.

Actions:
It is the only muscle that can flex the distal interphalangeal joints of the fingers. It also flexes at metacarpophalangeal joints and at the wrist.

Innervation:
The medial half (acts on the little and ring fingers) is innervated by the ulnar nerve. The lateral half (acts on the middle and index fingers) is innervated by the anterior interosseous branch of the median nerve.

Blood supply:
Ulnar, common interosseous, ulnar collateral, ulnar recurrent, anterior interosseous, median arteries

Question 16

Flexor Pollicis Longus (Deep Compartment)

Answer 16

Attachments:
Originates from the anterior surface of the radius and surrounding interosseous membrane. Attaches to the base of the distal phalanx of the thumb.

Actions:
Flexes the interphalangeal joint and metacarpophalangeal joint of the thumb.

Innervation: Median nerve (anterior interosseous branch).

Blood supply:
Medial part: anterior interosseous artery (ulnar artery); lateral part: radial artery

Question 17

Pronator quadratus (Deep Compartment)

Answer 17

Attachments:
Originates from the anterior surface of the ulna and attaches to the anterior surface of the radius.

Actions:
Pronates the forearm.

Innervation:
Median nerve (anterior interosseous branch).

Blood supply:
Anterior interosseous artery

Question 18

Brachioradialis (Superficial Muscle)

Answer 18

Attachments:
Originates from the proximal aspect of the lateral supracondylar ridge of humerus, and attaches to the distal end of the radius, just before the radial styloid process.

Actions:
Flexes at the elbow.

Innervation:
Radial nerve.

Blood supply:
Radial artery, radial recurrent arteries, radial collateral artery

Question 19

Extensor Carpi Radialis Longus and Brevis (Superficial Muscle)

Answer 19

Attachments:
The ECRL originates from the lateral supracondylar ridge of the humerus, while the ECRB originates from the lateral epicondyle. Their tendons attach to metacarpal bones II and III.

Actions:
Extends and abducts the wrist.

Innervation:
Radial nerve.

Blood supply:
Radial recurrent artery, radial collateral artery, radial artery

Question 20

Extensor Digitorum Communis (Superficial Muscle)

Answer 20

Attachments:
Originates from the lateral epicondyle. The tendon continues into in the distal part of the forearm, where it splits into four, and inserts into the extensor hood of each finger.

Actions:
Extension of the digits at the interphalangeal and metacarpophalangeal joints.

Innervation:
Radial nerve (deep branch).

Blood supply:
posterior interosseous artery and the radial recurrent artery.

Question 21

Extensor Digiti Minimi (Superficial Muscle)

Answer 21

Attachments:
Originates from the lateral epicondyle of the humerus. It attaches, with the extensor digitorum tendon, into the extensor hood of the little finger.

Actions:
Extends the little finger, and contributes to extension at the wrist.

Innervation:
Radial nerve (deep branch).

Blood supply:
Radial recurrent artery, anterior interosseous artery, posterior interosseous artery

Question 22

Extensor Carpi Ulnaris (Superficial Muscle)

Answer 22

Attachments:
Originates from the lateral epicondyle of the humerus, and attaches to the base of metacarpal V.

Actions:
Extension and adduction of wrist.

Innervation:
Radial nerve (deep branch).

Blood supply:
Radial recurrent artery, posterior interosseous artery

Question 23

Anconeus (Superficial Muscle)

Answer 23

Attachments:
Originates from the lateral epicondyle, and attaches to the posterior and lateral part of the olecranon.

Actions:
Extends and stablises the elbow joint. Abducts the ulna during pronation of the forearm.

Innervation:
Radial nerve.

Blood supply:
Posterior interosseous recurrent artery

Question 24

Supinator (Deep Muscle)

Answer 24

Attachments:
It has two heads of origin. One originates from the lateral epicondyle of the humerus, the other from the posterior surface of the ulna. They insert together into the posterior surface of the radius.

Actions:
Supinates the forearm.

Innervation:
Radial nerve (deep branch).

Blood supply:
Radial recurrent artery, posterior interosseous artery, posterior interosseous recurrent artery

Question 25

Abductor Pollicis Longus (Deep Muscle)

Answer 25

Attachments:
Originates from the interosseous membrane and the adjacent posterior surfaces of the radius and ulna. It attaches to the lateral side of the base of metacarpal I.

Actions:
Abducts the thumb.

Innervation:
Radial nerve (posterior interosseous branch).

Blood supply:
Anterior interosseous artery, posterior interosseous artery

Question 26

Extensor Pollicis Brevis (Deep Muscle)

Answer 26

Attachments:
Originates from the posterior surface of the radius and interosseous membrane. It attaches to the base of the proximal phalanx of the thumb.

Actions:
Extends at the metacarpophalangeal and carpometacarpal joints of the thumb.

Innervation:
Radial nerve (posterior interosseous branch).

Blood supply:
Posterior interosseous artery, anterior interosseous artery

Question 27

Extensor Pollicis Longus (Deep Muscle)

Answer 27

Attachments:
Originates from the posterior surface of the ulna and interosseous membrane. It attaches to the distal phalanx of the thumb.

Actions:
Extends all joints of the thumb: carpometacarpal, metacarpophalangeal and interphalangeal.

Innervation:
Radial nerve (posterior interosseous branch).

Blood supply:
Posterior interosseous artery, anterior interosseous artery

Question 28

Extensor Indicis Proprius (Deep Muscle)

Answer 28

Attachments:
Originates from the posterior surface of the ulna and interosseous membrane, distal to the extensor pollicis longus. Attaches to the extensor hood of the index finger.

Actions:
Extends the index finger.

Innervation:
Radial nerve (posterior interosseous branch).

Blood supply:
Posterior and anterior interosseous artery

Question 29

Opponens Pollicis (Thenar Muscle)

Answer 29

Attachments:
Originates from the tubercle of the trapezium and the associated flexor retinaculum. It inserts onto the lateral margin of the first metacarpal.

Actions:
Opposes the thumb, by medially rotating and flexing the metacarpal on the trapezium.

Innervation:
Median nerve (recurrent branch).

Blood supply:
Superficial palmar branch of radial artery

Question 30

Abductor Pollicis Brevis (Thenar Muscle)

Answer 30

Attachments:
Originates from the tubercles of the scaphoid and trapezium, and from the associated flexor retinaculum. Attaches to lateral side of proximal phalanx of the thumb.

Actions:
Abducts the thumb.

Innervation:
Median nerve (recurrent branch).

Blood supply:
Superficial palmar branch of radial artery

Question 31

Flexor Pollicis Brevis (Thenar Muscle)

Answer 31

Attachments:
Originates from the tubercle of the trapezium and from the associated flexor retinaculum. Attaches to the base of the proximal phalanx of the thumb.

Actions:
Flexes the metacarpophalangeal joint of the thumb.

Innervation:
Median nerve (recurrent branch). The deep head is innervated by the deep branch of the ulnar nerve.

Blood supply:
Superficial palmar artery, princeps pollicis artery and radialis indicis artery

Question 32

Opponens Digiti Minimi (Hypothenar Muscle)

Answer 32

Attachments:
Originates from the hook of hamate and associated flexor retinaculum, inserts into the medial margin of metacarpal V.

Actions:
It rotates the metacarpal of the little finger towards the palm, producing opposition.

Innervation:
Ulnar nerve.

Blood supply:
Deep palmar branch of ulnar artery, deep palmar arch

Question 33

Abductor Digiti Minimi (Hypothenar Muscle)

Answer 33

Attachments:
Originates from the pisiform and the tendon of the flexor carpi ulnaris. It attaches to the base of the proximal phalanx of the little finger.

Actions:
Abducts the little finger.

Innervation:
Ulnar nerve.

Blood supply:
Palmar branch of ulnar artery, palmar digital artery, superficial palmar arch

Question 34

Flexor Digiti Minimi Brevis (Hypothenar Muscle)

Answer 34

Attachments:
Originates from the hook of hamate and adjacent flexor retinaculum, and inserts into the base of the proximal phalanx of the little finger.

Actions:
Flexes the metacarpophalangeal joint of the little finger.

Innervation:
Ulnar nerve.

Blood supply:
Deep palmar branch of ulnar artery

Question 35

Lumbricals

Answer 35

Attachments:
Each lumbrical originates from a tendon of the flexor digitorum profundus. They pass dorsally and laterally around each finger, and inserts into the extensor hood.

Actions:
Flexion at the MCP joint and extension at the interphalangeal (IP) joints of each digit.

Innervation:
The lateral two lumbricals (of the index and middle fingers) are innervated by the median nerve. The medial two lumbricals (of the little and ring fingers) are innervated by the ulnar nerve.

Blood supply:
Dorsal carpal arch (dorsal metacarpal and dorsal digital arteries), superficial palmar arch (common palmar metacarpal arteries)

Question 36

Dorsal Interossei

Answer 36

Attachments:
Each interossei originates from the lateral and medial surfaces of the metacarpals. They attach into the extensor hood and proximal phalanx of each finger.

Actions:
Abduction of the digits. Assists in flexion at the metacarpophalangeal joints and extension at the interphalangeal joints.

Innervation:
Ulnar nerve.

Blood supply:
1: First dorsal metacarpal artery (radial artery)
2, 3 & 4: Second, third, and fourth dorsal metacarpal arteries (dorsal carpal anastomosis)

Question 37

Palmar Interossei

Answer 37

Attachments:
Each interossei originates from a medial or lateral surface of a metacarpal, and attaches into the extensor hood and proximal phalanx of same finger.

Actions:
Adduction of the digits. Assists in flexion at the metacarpophalangeal joints and extension at the interphalangeal joints.

Innervation:
Ulnar nerve.

Blood supply:
Deep palmar arch, princeps pollicis artery, radialis indicis artery, palmar metacarpal arteries, proximal and distal perforating arteries, common and proper palmar arteries

Question 38

Palmaris Brevis

Answer 38

Attachments:
Originates from the palmar aponeurosis and flexor retinaculum, attaches to the dermis of the skin on the medial margin of the hand.

Actions:
Wrinkles the skin of the hypothenar eminence and deepens the curvature of the hand, improving grip.

Innervation:
Ulnar nerve.

Blood supply:
Superficial palmar arch

Question 39

Adductor Pollicis

Answer 39

Attachments:
One head originates from metacarpal III. The other head originates from the capitate and adjacent areas of metacarpals II and III. Both attach into the base of the proximal phalanx of the thumb.

Actions: Adductor of the thumb.

Innervation: Ulnar nerve.

Blood supply:
Deep palmar arch