L3.2 Shoulder and Arms

Question 1

Manubrium

Answer 1

• Main UL attachment
• Central depression (Jugular (suprasternal) notch)
• Clavicular notch
• Costal notch (for 1st rib)

Question 2

Clavicle

Answer 2

• Separates & connects appendicular/articular skeleton
• Is an atypical long bone
  
  • Mix endochondrial & intermembranosus (mid part) ossification
  • Earliest bone for ossification but last bone to end
    
    • ∴ able to forensically determine age
  • No medullary cavity, but still has bone marrow
• 2 ends: sternal & acromial (lat)
• S-shaped → dissipates force into manubrium (∴weight bearing)

Question 3

Common fracture of the Clavicle

Answer 3

• From FOOSH
• At lat 1/3 & med 2/3
• SCM pulls clavicle upwards while lats/deltoids pull clavicle downwards
  
  • Clavicle may not heal properly if left alone

Question 4

Scapula

Answer 4

• Glenoid cavity faces laterally (shallow → allows mobility)
• Suprascapular notch, transverse ligament runs across → creates suprascapular foramen
  
  • Suprascapular nerve goes through foramen
    
    • Supraspinatus hypertrophy → compress
  • Suprascapular A. is superior to lig
• Med & Lat border
• Coracoid process (follows from suprascapular notch)
• ANT: Subscapular fossa
• POS: Spine of scapular
  
  • Divides Infra & suprascapular fossa
• Acromion process at the end of spine

Question 5

Humerus

Answer 5

• Head of humerus (only forms 1/3 sphere→allows fitting into glenoid cavity→↑mobility)
• Anatomical neck ~ head
• Surgical neck ~ end of groove
• Greater & lesser tubercle (bony projections)
• Intertubercular groove (bicipital groove)
• Deltoid tuberosity
• Distal end → wider → Lat & Med epicondyle
• Trochlear (ulnar); Capitulum (Head of Radius)
• ANT: Radial, trochlear fossa; POS: Olecranon fossa

Question 6

Common fracture of the Humerus?

Answer 6

• Surgical neck → inhibit axillary nerve & posterior humeral circumflex A.
• Mid shaft → Inhibits radial nerve & deep radial A
• Supracondylar → Inhibits median nerve & brachial A
• Med epicondyle → inhibits Ulnar nerve

Question 7

POS superficial shoulder muscles (2)

Answer 7

• Trapezius: Origin: Spinous process; Insertion: Pos border of 1/3 lat clavicle, Spine/acromion process of scapula
  
  • Many functions
  • Innervated by 11th cranial nerve
• Latissimus Dorsi: Origin: Spinous process ~T6; Insert : Intertubercular groove
  
  • Extends and rotates arm

Question 8

POS deep shoulder muscles (2)

Answer 8

• Levator scapulae: Origin: transverse process of C1-4; Insertion: superior part of Med scapula
• Rhomboids: Origin: spinous process of C7 – T5, insertion: Med border of scapula
  
  • Retraction of scapula
  • Nerve supply from brachial plexus

Question 9

ANT Superficial shoulder muscles (4)

Answer 9

• Pec major: Origin: Clavicle & Sternum; Insertion: Intertubercular groove
  
  • Adduction & Internal rotation
• Pec minor: Origin: 3rd-5th rib; Insertion: Coracoid process of scapula
  
  • Lift ribs up, Protraction (pull forwards) of scapula
• Subclavius: Origin: 1st rib; Insertion: Subclavian groove of clavicle
  
  • Depresses clavicle
• Serratus ANT: Origin: Upper 8/9 ribs; Insertion: Med Scapula
  
  • Position scapular against rib cage
  • Nerve supply lies in superior aspect – is exposed (usually deep for others)
    
    • Nerve damaged → causes ‘winging’ of scapula (scapula not positioned against ribcage)

Question 10

ANT intrinsic shoulder muscles (originate from scapula) (5)

Answer 10

• Deltoids: Origin: Clavicle & Spine of scapula; Insertion: Deltoid tuberosity
  
  • ANT fibres: Flexes arm
  • POS fibres: Extends arm
  • Med fibres: Abduct arm
  • Collective: Abductors
  • Pulls humerus back when dropped
• Rotator cuff muscles: (SITS)
  
  • Supraspinatus - AB
  • Infraspinatus - L.R
  • Teres Minor - L.R
  • Subscapularis - M.R
  • Fixators → stabilises joint
  • Injuries: Impingement of Supraspinatus (works in small space)
    
    • Painful arc syndrome (Pain when abducting)
    • Adhesive capsulitis (frozen shoulders) – influence syno fluid/capsule

Question 11

ANT Arms (3)

Answer 11

• Biceps: Origin: LH: supraglenoid; SH: Coracoid; Insertion: Radial tuberosity & bicipital aponeurosis
  
  • Short head: looks longer
  • Long head: Looks shorter due to going intracapsular & passes through interterbucular groove
  • Flexes & supination of arm (when already flexed)
• Coracobrachialis: Origin: Scapula; Insertion: Med shaft of humerus
  
  • Works with biceps
• Brachialis: Origin: From where coracobrachialis inserts; Insertion: Ulnar tuberosity (deep to bicipital aponeurosis)

Question 12

Three types of Biceps Injury?

Answer 12

• Tendinitis: inflammation of tendon
• Rupture
• Dislocation (tendon breaks away): Forms Popeye syndrome

Question 13

POS Arms (2)

Answer 13

• Triceps: Origin: LH: Infraglenoid T. ; MED+LAT H (lat+med) from shaft of humerus; Insertion: olecranon in ulnar
  
  • *3 Bellies converge → insert in olecranon*
• Anconeus: Origin: supra lat epicondyle; Insertion: Olecranon
  
  • Assists triceps

Question 14

What are the structures that go through the 3 POS apertures?

And what are the borders defining each aperture?

Answer 14

• Quadrangular space
  
  • Axillary N, Posterior humeral circumflex A
• Triangular Space
  
  • Circumflex scapula A → major supply to scapula
• Triangular interval
  
  • Radial N, Deep brachial A