Muscles and Nerves Flashcards
Deltoid
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
supraspinatus
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
infraspinatus
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
teres minor
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
subscapularis
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
Extrinsic shoulder muscles
trapezius and latissimus dorsi = superficial extrinsic muscles
levator scapulae and rhomboids = deep extrinsic shoulder muscles
Trapezius
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
Latissimus Dorsi
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
pectoralis major
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
Pecoralis minor
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
serratus anterior
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
Biceps brachii
proximal: long head attaches to supraglenoid tubercle of scapula / short head: coracoid process of scapula
distal: radial tuberosity
action: flexes forearm at elbow joint
coracobrachialis
proximal: coracoid process of scapula
distal: middle third of humerus
action: works with anterior deltoid to flex arm while walking
lateral cutaenous nerve of forearm
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
medial cutaneous nerve of arm
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
posterior cutaneous nerve of forearm
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
medial cutaneous nerve of ARM
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
posterior cutaneous nerve of ARM
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
flexor carpi radialis (FCR)
proximal: medial epidondyle of humerus (common flexor origin)
distal: base of 2nd metacarpal
innervationL median nerve (C6, C7)
flexes and abducts hand (at wrist)
palmaris longus
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
flexor carpi ulnaris (FCU) humeral head
proximal: medial epicondyle of humerus
distal: pisiform hook of hamate, 5th metacarpal
innervation: ulnar nerve (C7, C8)
action: flexes and adducts hand (at wrist)
flexor carpi ulnaris: (ulnar head)
proximal attachment: olecranon and posterior border (via aponeurosis)
erryting else is the same as the humeral head
**adducts hand
flexor digitorum superficialis (FDS) - humeroulnar head and radial head
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. **
flexor digitalis profundus (FDP) of deep muscle layer
distal attachment: bases of distal phalanges of digits 2-5
action: flexes distal phalanges (2-5) at distal interphalangeal joint
flexor pollicis longus (FPL)
distal attachment:
action: flexion of both pahalanges of digit 1
