Muscles and Nerves

Question 1

Deltoid

Answer 1

proximal attachment: lateral third of clavicle; acromion and spine of scapula

distal attachment: deltoid tuberosity of humerus

innervation: axillary nerve (C5,C6)

Muscle action:

• clavicular: flexes and medially rotates arm
  acromial: abducts arm
  spinal: extends and laterally roatates arm

Question 2

supraspinatus

Answer 2

proximal attachment: supraspinous fossa of scapula

distal attachment: superior facet of greater tubercle of humerus

innervation: suprascapular nerve (C4, C5, C6)
action: initiates (first 15 degrees) and assists deltoid in abduction of arm and acts with rotator cuff muscles

Question 3

infraspinatus

Answer 3

proximal: infraspinous fossa of scapula
distal: middle facet of greater tubercle of humerus
innervation: suprascapular nerve (C4, C5, C6)
action: laterally rotates arm and acts with rotator cuff muscles

Question 4

teres minor

Answer 4

proximal: middle part of lateral border of scapula
distal: inferior facet of greater tubercle of humerus
innervation: axillary nerve (C5, C6)
action: laterally rotates arm and acts with rotator cuff muscles

Question 5

subscapularis

Answer 5

proximal: subscapular fossa (anterior surface of scapula)

distal attachment: lesser tubercle of humerus

innervation: upper and lower subscapular nerves (C5, C6, C7)
action: medially rotates arm; as part of rotator cuff, helps keep humerus in glenoid cavity

Question 6

Extrinsic shoulder muscles

Answer 6

trapezius and latissimus dorsi = superficial extrinsic muscles

levator scapulae and rhomboids = deep extrinsic shoulder muscles

Question 7

Trapezius

Answer 7

proximally: cervical and thoracic vertebrae (C7-T12)
distally: lateral 3rd of clavicle; acromion and spine of scapula
innervation: spinal acessory nerve and C3,4 spinal nerves (pain and proprioception)

muscle action: descending part elevates, ascending part depresses, middle part retracts scapula. Descending and ascending parts act together to rotate glenoid cavity superiorly

Question 8

Latissimus Dorsi

Answer 8

proximal: spinous process of inferior 6 thoracic vertebrae, thoracolumbar fascia, iliac crest, and interior 3-4 ribs
distally: floor of intertubercular sulcus of humerus
innervation: thoracodorsal nerve (**C6, C7, **C8)

extends, adducts, and medially rotates humerus; raises body toward arms during climbing

Question 9

pectoralis major

Answer 9

proximal attachment: clavicular head: anterior surface of medial half of clavicle. Sternocostal head: anterior surface of sternum, superior 6 costal cartillages, aponeurosis of external oblique muscle

distal attachment: lateral lip of intertubercular sulcus of humerus

innervation: clavicular head (lateral and medial pectoral nerves [C5, C6]) / sternocostal head (C7, C8, T1)

main action: adducts and medially roates humerus, draws scapula anteriorly and inferiorly. Acting alone, calvicular head flexes humerus and sternocostal head extends it from the flexed position

Question 10

Pecoralis minor

Answer 10

proximal attachment: 3-5th ribs near their costal cartillages

distal attachment: medial border and superior surface of coracoid process of scapula

innervation: medial pectoral (C8, T1)
action: stabilizes scapula by drawing it inferiorly and anteriorly against thoracic wall

Question 11

serratus anterior

Answer 11

proximal attachment: external surface of lateral parts of 1-8 ribs

distal attachment: medial border of scapula

innervation: long thoracic nerve (C5, C6, C7)
action: protacts scapula and holds it against thoracic wall; rotates scapula

Question 12

Biceps brachii

Answer 12

proximal: long head attaches to supraglenoid tubercle of scapula / short head: coracoid process of scapula
distal: radial tuberosity
action: flexes forearm at elbow joint

Question 13

coracobrachialis

Answer 13

proximal: coracoid process of scapula
distal: middle third of humerus
action: works with anterior deltoid to flex arm while walking

Question 14

lateral cutaenous nerve of forearm

Answer 14

contributing spinal nerves: C6-C7

source: muskuocutaneous nerve (terminal branch)

course and direction: emerges lateral to biceps tendon deep to cephalic vein, supplying skin of enterolateral forearm to wrist

Question 15

medial cutaneous nerve of arm

Answer 15

Contributing spinal nerves: C8, T1

source: medial cord of brachial plexus (in axialla)

course and distribution: descends medial to brachial artery, pierces deep fascia with basilic vein in miderm, dividing into anterior and posterior branches that enter forearm and supply skin of anteromedial aspect to wrist

Question 16

posterior cutaneous nerve of forearm

Answer 16

contributing spinal nerves: C5-C8

source: radial nerve (with inferior lateral cutaneous nerve of arm)

course and distribution: perforates lateral head of triceps, descends laterally in arm, then runs along and supplies posterior forearm to wrist

Question 17

medial cutaneous nerve of ARM

Answer 17

Contributing Spinal nerves: C8-T2

source: medial cord of brachial plexus (in axialla)

course and distribution: communicates with intercostobrachial nerve, continues to suply skin of medial aspect of distal arm

Question 18

posterior cutaneous nerve of ARM

Answer 18

Contributing Spinal Nerves: C5-C8

source: radial nerve (in axilla)

course and direction: crosses posterior to and communicates with intercostobracial nerve and supplies skin of posterior arm as far as olecranon

Question 19

flexor carpi radialis (FCR)

Answer 19

proximal: medial epidondyle of humerus (common flexor origin)
distal: base of 2nd metacarpal

innervationL median nerve (C6, C7)

flexes and abducts hand (at wrist)

Question 20

palmaris longus

Answer 20

proximal: medial epicondyle of humerus

distal half of flexor retinaculum and apex of palmar

innervation: median nerve (C7, C8)

flexes hand (at wrist) and tenses palmar aponeurosis

Question 21

flexor carpi ulnaris (FCU) humeral head

Answer 21

proximal: medial epicondyle of humerus
distal: pisiform hook of hamate, 5th metacarpal
innervation: ulnar nerve (C7, C8)

action: flexes and adducts hand (at wrist)

Question 22

flexor carpi ulnaris: (ulnar head)

Answer 22

proximal attachment: olecranon and posterior border (via aponeurosis)

erryting else is the same as the humeral head

**adducts hand

Question 23

flexor digitorum superficialis (FDS) - humeroulnar head and radial head

Answer 23

proximal: humerolunar head: medial epicondyle / radial head: superior half of anterior border
proximal: shafts of middle phalanges of medial 4 digits
innervation: median nerve (C7, C8, T1)

**main action: flexes middle phalanges at proximal interphalangeal joints of middle 4 digits. **

Question 24

flexor digitalis profundus (FDP) of deep muscle layer

Answer 24

distal attachment: bases of distal phalanges of digits 2-5

action: flexes distal phalanges (2-5) at distal interphalangeal joint

Question 25

flexor pollicis longus (FPL)

Answer 25

distal attachment:

action: flexion of both pahalanges of digit 1