Lecture 16- Arm and Shoulder

Question 0

Humerus
• Long bone
• Proximal head articulates with ……… …….. of scapula
• Distal medial and lateral epicondyles articulate at elbow with ulna and radius
• Surgical neck common fracture site which can endanger which nerve?

Answer 0

glenoid cavity

Axillary nerve

Question 1

Intermuscular septum divides arm into anterior (…….) &
posterior (……..) compartments.

Answer 1

flexor

extensor

Question 2

Anterior compartment of arm
• Muscles are primarily flexors of forearm at elbow
• Secondarily flexors of arm at shoulder (biceps brachii &
coracobrachialis)
• Innervated by ……………. nerve
• Blood supply by ………. artery

Answer 2

musculocutaneous

brachial

Question 3

Posterior compartment
• Primarily extensors of the forearm at elbow.
• Blood supply from deep artery of arm (profunda brachii).
• Innervated by radial nerve.

Answer 3

.

Question 4

Blood supply of the upper limb

Aorta ->Brachiocephalic trunk ->Subclavian artery ->Axillary artery ->Brachial artery-> Radial artery->Ulnar artery

Answer 4

.

Question 5

Blood supply of the arm Brachial artery supplies anterior arm muscles
Deep brachial artery (profunda brachii) supplies posterior arm
muscles

Answer 5

.

Question 6

Innervation of arm muscles
Musculocutaneous nerve (lateral cord of brachial plexus)
Biceps brachii -> Brachialis ->Coracobrachialis

Radial nerve
(posterior cord of brachial plexus) ->Triceps brachii ->Anconeus

Answer 6

.

Question 7

Superior appendicular skeleton 
Bones of arm & shoulder comprised of: 
 • Pectoral girdle = 
-> Clavicle 
-> Scapula 

+ Humerus

Answer 7

.

Question 8

Clavicle
• Cylindrical bone.
• Slight “s” curve
• Formed by intra-membranous ossification (1st long bone to ossify).
• Most commonly fractured bone.
• Acts as a strut to keep limb away from trunk

Answer 8

.

Question 9

Scapula
• Flat triangular bone. 
• Shallow glenoid cavity. 
• Attachment location for 17 muscles. 
• Uncommon to fracture.

Answer 9

.

Question 10

Joints of the pectoral girdle 
& shoulder 
• Acromioclavicular joint 
• Glenohumeral joint 
• Sternoclavicular joint

Answer 10

.

Question 11

Acromioclavicular joint
• Synovial plane joint.
• Allows gliding movement as arm is raised and scapula rotates.
• Includes:
- Acromioclavicular joint capsule & ligament
- Coracoclavicular (conoid and trapezoid ligaments)

Answer 11

.

Question 12

Glenohumeral joint
• Multi-axial synovial ball-and-socket joint.
• Shallow articulation.
• Most common dislocated joint (95% anterior: subcoracoid,
subglenoid, subclavicular)
• Stabilised by rotator cuff muscles.
• Permits flexion, extension, abduction, adduction, protraction,
retraction, circumduction.

Answer 12

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