Muscles Of The Arm And Shoulder

Question 1

Coracobrachialis

Answer 1

Anterior compartment arm
Origin: apex of coracoid process
Insertion: linear roughening on mid shaft of the humerus on medial side
Innervation: musculocutaneous nerve C5 C6 C7
Function: flexor of the arm at the glenohumeral joint

Question 2

Biceps brachii

Answer 2

Anterior compartment of the arm
Origin: long head-supraglenoid tubercle of scapula, short head- apex of coracoid process
Insertion: radial tuberosity
Innervation: musculocutaneous nerve C5 C6
Function: powerful flexor of forearm at elbow joint and supinator of the forearm, accessory flexor of arm at gelnohumeral joint

Question 3

Brachialis

Answer 3

Anterior compartment of the arm
Origin: anterior aspect of humerus (medial and lateral surfaces) and adjacent intermuscular septae
Insertion: tuberosity of the ulna
Innervation: musculocutaneous nerve C5 C6 small contribution by radial nerve C7 to lateral part or muscle
Function: powerful flexor of forearm at elbow joint

Question 4

Triceps brachii

Answer 4

Posterior compartment of arm
Origin: long head- infraglenoid tubercle of scapula, medial head- posterior surface of humerus, lateral head- posterior surface of humerus
Insertion: olecranon
Innervation: radial nerve C6 C7 C8
Function: extension of the forearm at the elbow joint, long head can also extend and adduct the arm at the shoulder joint

Question 5

Deltoid

Answer 5

Origin: inferior edge of crest of spine of scapula, lateral margin of acromion, anterior border of lateral 1/3 clavicle
Insertion: deltoid tuberosity of humerus
Innervation: axillary nerve C5 C6
Function: major abductor of arm; clavicular fibres assist in flexing arm; posterior fibres assist in extending arm

Question 6

Supraspinatus

Answer 6

Rotator cuff muscle
Origin: medial 2/3 of supraspinous fossa of scapula and deep fascia that covers the muscle
Insertion: most superior facet on greater tubercle of humerus
Innervation; suprascapular nerve C5 C6
Function: abduction of glenohumeral joint, stabilisation of the joint

Question 7

Infraspinatus

Answer 7

Rotator cuff
Origin; medial 2/3 infraspinous fossa of the scapula and the deep fascia that covers the muscle
Insertion: middle facet on posterior surface of greater tubercle of humerus
Innervation: suprascapular nerve C5 C6
Function: lateral rotation arm at GHJ and stabilisation

Question 8

Teres minor

Answer 8

Rotator cuff
Origin: upper 2/3 of flattened strip of bone on posterior surface of scapula immediately adjacent to lateral border of scapula
Insertion: inferior facet on posterior surface of greater tubercle of humerus
Innervation: axillary nerve C5 C6
Function: lateral rotation of arm at GHJ and stabilisation

Question 9

Teres major

Answer 9

Origin: elongate oval area on posterior surface of inferior angle of scapula
Insertion: medial lip of the intertubercular sulcus on anterior surface of humerus
Innervation: inferior subscapular nerve C5 C6 C7
Function: medial rotation and extension arm at GHJ and stabilisation of joint

Question 10

Subscapularis

Answer 10

Rotator cuff
Origin: subscapular fossa- anterior surface scapula
Insertion: lesser tubercle of humerus
Innervated: superior and inferior subscapular nerves C5 C6
Function: medial rotation and Adduction, stabilising joint