Lecture 15: Muscular System Upper Limb

Question 1

Muscles attaching upper limb to trunk

Answer 1

Pectoralis major and minor
Serratus anterior
Trapezius
Latissimus dorsi
Rhomboids
Levator scapulae

Question 2

Muscles of upper limb

Answer 2

Scapular
Deltoid
Arm
Forearm
Hand

Question 3

Rotator cuff

Answer 3

Subscapularis
Supraspinatus
Infraspinatus
Teres minor
Function: reinforce shoulder joint capsule (except the inferior aspect) and stabilize the joint

Question 4

Supraspinatus

Answer 4

Origin: supraspinous fossa
Insertion: greater tubercle of humerus
Function: prime mover for abduction of shoulder for first 30 degrees
Nerve: branch of brachial plexus

Question 5

Infraspinatus

Answer 5

Origin: infraspinous fossa
Insertion: greater tubercle of humerus
Function: lateral rotation of shoulder
Nerve: branch of brachial plexus

Question 6

Subscapularis

Answer 6

Origin: subscapular fossa
Insertion: lesser tubercle of humerus
Function: prime mover for medial rotation of shoulder
Nerve: 2 branches of brachial plexus

Question 7

Deltoid

Answer 7

Origin: clavicle, acromian, spine of scapula (U shaped)
Insertion: deltoid tuberosity
Function: prime mover of abduction of shoulder from 30-90 degrees
Nerve: axillary nerve of brachial plexus

Question 8

Muscles of arm

Answer 8

Contains 2 compartments made by humerus and extensions of deep fascia/inter-muscular septum attaching to humerus
Anterior compartment
Posterior compartment

Question 9

Anterior compartment of arm

Answer 9

Biceps brachii
Brachialis
Coracobrachialis
Mainly flex shoulder/elbow joints
Innervated by musculocutaneous nerve of brachial plexus

Question 10

Posterior compartment of arm

Answer 10

Triceps brachii
Mainly extend shoulder/elbow joints
Innervated by radial nerve of brachial plexus

Question 11

Biceps brachii

Answer 11

2 heads
Origin: long head - above glenoid fossa, short head - corocoid process
Insertion: radial tuberosity
Function: flexor of elbow, weak flexor of shoulder, prime mover for supination of forearm
Nerve: musculocutaneous nerve

Question 12

Brachialis

Answer 12

Origin: anterior surface of humerus
Insertion: ulnar tuberosity
Function: prime mover for flexion of elbow
Nerve: musculocutaneous nerve

Question 13

Triceps brachii

Answer 13

3 heads
Origin: long head - scapula below glenoid fossa, lateral/medial head - posterior surface of humerus
Insertion: olecranon process
Function: prime mover for extension of elbow, only long head extends shoulder
Nerve: radial nerve

Question 14

Muscles of forearm

Answer 14

Has anterior and posterior compartments

Divided by radius, ulna, interosseous membrane, extension of deep fascia attaching to radius

Question 15

Anterior compartment of forearm

Answer 15

Subdivided into superficial (pronator teres, flexor carpi radialis), intermediate (flexor digitorum superficialis), deep (flexor digitorum profundus, flexor pollicis longus) layer
Most common origin: medial epicondyle of humerus (common flexor tendon)
Insertion: radius, metacarpals, phalanges
Involved in pronation of forearm, flexion of wrist and fingers
Innervated by median or ulnar nerves

Question 16

Posterior compartment of forearm

Answer 16

Subdivided into superficial (brachioradialis, extensor digitorum, extensor carpi ulnaris) and deep (supinator, extensor indicis, abductor pollicis) layer
Most common origin: lateral epicondyle of humerus (common extensor tendon)
Insertion: radius, metacarpals, phalanges
Involved in supination of forearm, extension of fingers and wrist
Innervated by radial nerve

Question 17

Extensor hood or dorsal digital expansion

Answer 17

Tendons of extensor muscles form triangular expansion on dorsal proximal phalanges
Receives tendons of lumbricals and interossei muscles
Inserts to middle and distal phalanges

Question 18

Extensor retinaculum

Answer 18

Holds tendons of muscles in the posterior compartment by thickening of deep fascia
Passes behind wrist

Question 19

Pronator teres

Answer 19

Superficial layer of anterior compartment of forearm
Origin: medial epicondyle of humerus
Insertion: shaft or radius
Function: prime mover for pronation of forearm
Nerve: median nerve

Question 20

Flexor carpi radialis

Answer 20

Superficial layer of anterior compartment of forearm
Origin: medial epicondyle of humerus
Insertion: 2nd and 3rd metacarpal bone
Function: flexion of wrist, abduction of wrist (radial deviation)
Nerve: median nerve

Question 21

Flexor retinaculum

Answer 21

Thick band of dense connective tissue
Transversely passes in front of wrist
Holds all muscles of anterior compartment of forearm to increase overall efficiency

Question 22

Flexor digitorum superficialis

Answer 22

Intermediate layer of anterior compartment of forearm
Origin: medial epicondyle of humerus
Insertion: tendons splits into 4 and inserts to middle phalange of fingers 2-5
Function: flexor of wrist, flexor of metacarpal phalangeal joints and proximal interphalangeal joints
Nerve: median nerve

Question 23

Flexor digitorum profundus

Answer 23

Deep layer of anterior compartment of forearm
Origin: ulna
Insertion: distal phalangeal of fingers 2-5
Function: prime mover for flexion of wrist and all joints in fingers
Nerve: fingers 2-3 - median nerve, fingers 4-5 - ulnar nerve

Question 24

Flexor pollicis longus

Answer 24

Deep layer of anterior compartment of forearm
Origin: radius
Insertion: distal phalange of thumb
Function: prime mover for flexion of thumb
Nerve: median nerve

Question 25

Brachioradialis

Answer 25

*Physically sits in anterior compartment and flexes forearm, but is innervated by radial nerve Origin: lateral epicondyle of humerus Insertion: styloid process of radius Function: flexion of elbow (prime mover from 90-110 degrees) Nerve: radial nerve

Question 26

Extensor digitorum

Answer 26

Superficial layer of posterior compartment of forearm Origin: lateral epicondyle of humerus Insertion: middle and distal phalange of fingers 2-5 Function: prime mover for extension of fingers and wrist Nerve: radial nerve

Question 27

Extensor carpi ulnaris

Answer 27

Superficial layer of posterior compartment of forearm Origin: lateral epicondyle of humerus Insertion: 5th metacarpal bone Function: extension of wrist and adduction of wrist (ulnar deviation) Nerve: radial nerve

Question 28

Supinator

Answer 28

``` Deep layer of posterior compartment of forearm Origin: ulna and humerus Insertion: radius Function: supination of forearm Nerve: radial nerve ```

Question 29

Extensor indicis

Answer 29

Deep layer of posterior compartment of forearm Origin: ulna Insertion: middle and distal phalange of index finger Function: extends index finger independently Nerve: radial nerve

Question 30

Abductor pollicis longus

Answer 30

Deep layer of posterior compartment of forearm Origin: posterior shaft of ulna Insertion: 1st metacarpal bone and proximal phalange of thumb Function: prime mover for abduction of thumb Nerve: radial nerve

Question 31

Intrinsic muscles of hand

Answer 31

19 muscles 3 groups: Thenar Hypothenar Central (lumbricals, palmar/dorsal interossei, adductor pollicis) Mainly innervated by ulnar nerve, some by median nerve

Question 32

Thenar group of hand

Answer 32

Origin: carpal bones Insertion: 1st metacarpal bone or proximal phalanage of thumb Function: forms thenar eminence at base of thumb and moves thumb (abduction, flexion, opposition) Nerve: median nerve

Question 33

Hypothenar group of hand

Answer 33

Origin: carpal bone Insertion: 5th metacarpal bone or proximal phalange of 5th finger Function: forms hypothenar eminence at base of pinky and moves pinky (abduction, flexion, opposition) Nerve: ulnar nerve

Question 34

Central group of hand

Answer 34

Deep to the thickening of deep fascia of palm of hand = palmar aponeurosis Protects soft tissues at the center of the palm Contains adductor pollicis (only muscle in central group that moves thumb), lumbricals, dorsal and palmar interossei

Question 35

Lumbricals

Answer 35

4 superficial worm-like muscles underneath palmar aponeurosis of hand Origin: tendon of flexor digitorum profundus Insertion: middle and distal phalange of fingers 2-5 Function: flexion of metacarpal phalangeal joints, and extension of proximal and distal interphalangeal joints (tata movement) Nerve: half by median, and half by ulnar nerve

Question 36

Interossei

Answer 36

Origin: metacarpal bone Insertion: middle and distal phalange of fingers 2-5 Function: palmar - adduction of fingers (2, 4, 5), dorsal - abduction of fingers (2-4) Nerve: ulnar nerve

Question 37

Transitional areas of upper limb

Answer 37

Major blood vessels and nerves pass from one region to the next Axilla Cubital fossa Carpal tunnel

Question 38

Axilla

Answer 38

Pyramidal space between root of neck and shoulder (armpit) Axillary artery and vein, cords of brachial plexus pass through Has 4 walls, base, apex Anterior wall: pectorialis major and minor Medial wall: thoracic wall (until 5th rib) and serratus anterior muscle Posterior wall: subscapularis, teres major, latissimus dorsi, scapula Lateral wall: intertubercular groove of humerus Base: skin of armpit Apex: behind middle third of clavicle

Question 39

Cubital fossa

Answer 39

In front of elbow Median and radial nerves, and brachial artery pass through Triangular space Lateral: brachioradialis muscle Medial: pronator teres Superior: imaginary line joining medial and lateral epicondyles of humerus

Question 40

Carpal tunnel

Answer 40

Wrist Fibro-osseous tunnel by carpal bones and thickening of deep fascia (flexor retinaculum) in front of wrist Contains tendons of flexor digitorum superficialis, flexor digitorum profundus, flexor pollicis longus, median nerve

Question 41

Carpal tunnel syndrome

Answer 41

All tendons are double wrapped by synovial membrane which produces fluid to minimize friction between tendons and flexor retinaculum Overuse of muscles causes tendons and membranes to be inflammed causing swelling which compresses the median nerve Causes weakness in thenar muscles Also caused by pregnancy, hypothyroidism, collagen vascular disease