Brachial plexus and shoulder

Question 1

What is the origin of the brachial plexus?

Answer 1

Ventral rami C5-T1

Question 2

What are the sections of the brachial plexus?

Answer 2

Randy texans drink cold beer

(roots, trunks, divisions, cords, branches)

Question 3

Where are the roots of the brachial plexus located?

Answer 3

Pass between scalenus anterior and medius

Question 4

Where are the trunks of the brachial plexus located?

Answer 4

-upper and middle trunk are superior to subclavian
-Lower trunk runs posterior to subclavian

Edit:
-Run from base of posterior triangle
-Over first rib
-Behind first part of subclavian

Question 5

Where are the divisions of brachial plexus located?

Answer 5

Apex of axilla, lie behind middle 1/3rd of clavicle

Question 6

Where are the cords of the brachial plexus located?

Answer 6

My there names related to axillary artery
–> posterior
–> lateral
–> medial

Question 7

Draw out the brachial plexus

Answer 7

Upper roots:
-Long thoracic: C5-C7-serratus anterior
-Dorsal scapular: C5, rhomboids and levator scapulae

Upper trunk
-Nerve to subclavius: C5-C6, subclavius
-Suprascapular: C5,C6

Lateral cord:
-Lateral pectoral nerve (C5-C7)

Posterior cord
–> upper subscapular (upper part subscapularis)
–> lower subscapular (lower part subscapularis, teres major)
–> Thoracodorsal (LD)

Medial cord
-Medial pectoral nerve (part of pec major), pec minor
-Medial cutaneous nerve of arm
-Medial cutaneous nerve of forearm

Question 8

Answer 8

Question 9

Describe Erb’s palsy

Answer 9

Causes
-During newborn delivery
-Traumatic force downwards on arm and shoulder

-Damage to upper nerve roots C5,C6

Motor
–> Adduction: denervation arm abductors (deltoid, supraspinatus)
–> Internal rotation: denervation arm external rotators (teres minor, infraspinatus)
–> pronationand extension: denervation elbow flexors and supinators (biceps, brachialis, coracobrachialis)

Sensory
–> loss of sensation radial side of arm and forearm

Question 10

Describe Klumpke’s palsy

Answer 10

Injury to lower trunk (C8, T1)

Hyperabduction/birth trauma

Motor (claw hand deformity)
–> Denervation all intrinsic muscles of hand
–> paralysis of wrist flexors (except flexor carpi radialis-innervated by C6+7)
–> hyperextension MCP joints
–> flexion IP joints

Question 11

Answer 11

Question 12

Label posterior scapula

Answer 12

Question 13

Label lateral scapula

Answer 13

Question 14

label anterior scapula

Answer 14

Question 15

Answer 15

Question 16

left scapula and clavicle articulation from above

Answer 16

Question 17

Answer 17

Question 18

What is the origin and insertion of the pec major?

Answer 18

Origin

Clavicular head:
–> Medial half anterior clavicle

Sternocostal head
–> Anterior sternum
—> upper 6 costal cartilages
–> external oblique aponeurosis

Insertion
–> lateral intertrochanteric groove
–> Lateral lip of bicipital groove

Question 19

Pec major action

Answer 19

Whole muscle:
–> adduction and medial rotation of the arm

Clavicular head
–> Flexion of the humerus

Sternocostal head
–> extension of the flexed humerus
–> acts as accessory muscle of respiration by elevating the ribs

Question 20

What is the innervation of pec major?

Answer 20

-Medial (C8-T1) pectoral nerve
-Lateral (C5-C7) pectoral nerve

Question 21

What is the origin/insertion/innervation/action of trapezius?

Answer 21

Origin:
–> Spinous process T6-T12
–> Occipital protuberance
–> ligamentum nuchae

Insertion
–> Spine/acromion of scapula
–> clavicle

Action
–> rotates scapula

Innervation:
–> spinal accessory nerve (12th cranial nerve)

Question 22

What is origin/insertion/action/innervation of serratus anterior?

Answer 22

Origin
–> Ribs 1-9

Insertion
–> Scapula (ventral medial)

Action
–> prevents winging

Innervation
–> long thoracic nerve

Question 23

Deltoid origin/insertion

Answer 23

Origin:
–> spine of scapula, acromion
–> clavicle

Insertion
–> Humerus (deltoid tuberosity)

Question 24

Deltoid action/innervation

Answer 24

Action:

Anterior fibres
–> Flexion and internal rotation

Posterior fibres
–> Extension and external rotation

Middle fibres
–> major abductor of arm (after 15 degrees)

Innervation
–> axillary nerve

Question 25

Origin/insertion/action/innervation subscapularis

Answer 25

Origin: --> Subscapular fossa Insertion --> Humerus (LT) Action --> internally rotates arm --> provides anterior stability Innervation: --> upper and lower subscapular nerves (posterior cord of brachial plexus)

Question 26

Origin/insertion/action/innervation of supraspinatus/infraspinatus/teres minor

Answer 26

Origin: -Supraspinatus--> supraspinatus fossa -Infraspinatus--> infraspinatus fossa -Teres minor: --> dorsolateral scapula Insertion --> GT of humerus Action -Supraspinatus --> abducting, providing stability, externally rotating arm -Infraspinatus + teres minor --> external rotating, providing stability Innervation: -Supraspinatus and infraspinatus --> suprascapular nerve -Teres minor--> axillary nerve

Question 27

Answer 27

Question 28

Answer 28

Question 29

Answer 29

Question 30

What are the borders and contents of the triangular space?

Answer 30

Superior: teres minor Inferior: teres major Lateral: Long head of triceps Contents -Circumflex scapular artery

Question 31

What are the borders and contents of the triangular interval?

Answer 31

Borders: -Medial: long head of triceps -Lateral: Lateral head of triceps/humerus -superior: Teres major Contents -Profunda brachii artery -Radial nerve

Question 32

What are the borders and contents of the quadrangular space

Answer 32

-Medial: long head of triceps -Lateral: humerus -Superior: Teres minor -Inferior: teres major Contents -Axillary nerve -Posterior circumflex humeral artery

Question 33

What are the branches of the axillary artery?

Answer 33

Semen tastes like sweet apple pie 1st part (above pec minor) --> Superior thoracic artery 2nd part (posterior to pec minor) --> Thoracoacromial --> Lateral thoracic 3rd part (inferior to pec minor) --> Subscapular (largest branch) --> Anterior circumflex humeral --> posterior circumflex humeral

Question 34

Answer 34

Question 35

What is the surface marking of the coracoid process?

Answer 35

2cm inferior to junction between middle and lateral 1/3rd of the clavicle

Question 36

What structures attach to the coracoid process?

Answer 36

-Ligaments: --> Coracoclavicular --> coracohumeral --> coracoacromial Muscles --> pec minor (insertion) --> Coracobrachialis (origin) --> short head of biceps (origin)

Question 37

What muscles are inserted into the bicipital groove?

Answer 37

-A lady between two majors Lateral: Pec major Medial: teres major Floor: LD Tendon of long head of biceps lies within the groove

Question 38

Muscles involved in shoulder abduction

Answer 38

Supraspinatus 0-15 Middle fibres deltoid 15-90 >90 trapezius and serratus anterior, which will require upward rotation of the scapula with lateral rotation of the humerus

Question 39

What factors reduce the stability of the shoulder joint?

Answer 39

-Shallow glenoid cavity -Lax capsule with few ligaments -Inferior aspect not supported due to presence of quadrangular space

Question 40

What factors stabilise the shoulder?

Answer 40

Static restraints: -Glenoid labrum -Capsule -Glenohumeral ligaments Dynamic restraints -Rotator cuff ---> joint cavity depression produced by synchronised contraction of rotator cuff ---> Increased capsular tension due to attachments of rotator cuff to the capsule

Question 41

What is a synovial joint?

Answer 41

-Articulating surfaces covered in hyaline cartilage -Separated by film of synovial fluid that acts as a lubricant -Joint stability is provided by fibrous capsule and accessory ligaments -Synovial fluid is produced by synovial membrane that lines the joint capsule

Question 42

Describe axillary nerve motor and sensory supply, and deficit

Answer 42

Motor: -Deltoid -Teres minor Sensory -Skin to lower half deltoid (regimental badge) Injury -Inability to abduct arm beyond 15 degrees -sensory deficit over regimental badge area

Question 43

1,6,10,11,14

Answer 43

1,6,10,11,14

Question 44

Answer 44

Question 45

Answer 45

Question 46

Answer 46

Question 47

What are the upper limb myotomes?

Answer 47

C5: elbow flexion C6: wrist extension C7: elbow extension C8: finger flexion T1: finger abduction

Question 48

What are the reflexes?

Answer 48

1,2 buckle my shoe (ankle) 3,4 kick the door (knee) 5,6 pick up sticks (biceps and brachioradialis) 7,8 lay them straight (triceps)

Question 49

Dermatomes

Answer 49

C4: lateral neck and shoulder C5: lateral upper arm and elbow C6: lateral forearm and thumb C7: Middle finger C8: little finger and medial palm T1: Medial forearm and elbow

Question 50

What are the findings in upper limb nerve root compressions?

Answer 50

Question 51

What is the main stabiliser of the shoulder joint?

Answer 51

-Rotator cuff muscles