Upper limb anatomy

Question 1

How are muscles in the arm and forearm separated?

Answer 1

Muscles in the arm and forearm are separated into anterior (flexor) and posterior (extensor) compartments by layers of fascia, bones, and ligaments

Question 2

….muscles in the anterior compartment of the arm are innervated by the …. nerve.

Answer 2

All muscles in the anterior compartment of the arm are innervated by the musculocutaneous nerve.

Question 3

Which muscles are innervated by the median nerve?

Answer 3

The median nerve innervates the muscles in the anterior compartment of the forearm, with two exceptions—one flexor of the wrist (the flexor carpi ulnaris muscle) and part of one flexor of the fingers (the medial half of the flexor digitorum profundus muscle) are innervated by the ulnar nerve.

Question 4

Which nerve supplies the intrinsic muscles of the hand?

Answer 4

Most intrinsic muscles of the hand are innervated by the ulnar nerve, except for the thenar muscles and two lateral lumbrical muscles, which are innervated by the median nerve.

Question 5

Which nerve supplies the posterior compartment of the arm and forearm?

Answer 5

Radial n.

Question 6

Where does the axillary nerve come into contact with the humerus?

Answer 6

supplies the deltoid muscle, a major abductor of the humerus at the glenohumeral joint, passes around the posterior aspect of the upper part of the humerus (the surgical neck).

Question 7

Where does the radial nerve come into contact with the humerus?

Answer 7

which supplies all of the extensor muscles of the upper limb, passes diagonally around the posterior surface of the middle of the humerus in the radial groove.

Question 8

Where does the ulnar nerve come into contact with the humerus?

Answer 8

The ulnar nerve, which is ultimately destined for the hand, passes posteriorly to a bony protrusion, the medial epicondyle, on the medial side of the distal end of the humerus.

Question 9

What are the superficial muscles of the shoulder?

Answer 9

The superficial muscles of the shoulder consist of the trapezius and deltoid muscles, which together form the smooth muscular contour over the lateral part of the shoulder. These muscles connect the scapula and clavicle to the trunk and to the arm, respectively.

Question 10

What part of the humerus is most susceptible to injury?

Answer 10

The axillary nerve and the posterior circumflex humeral artery, which pass into the deltoid region from the axilla, do so immediately posterior to the surgical neck. Because the surgical neck is weaker than more proximal regions of the bone, it is one of the sites where the humerus commonly fractures.

Question 11

What is the origin of the trapezius muscle?

Answer 11

Superior nuchal line, external occipital protuberance, medial margin of the ligamentum nuchae, spinous processes of C7 to T12 and the related supraspinous ligaments

Question 12

What is the origin of the deltoid muscle?

Answer 12

Inferior edge of the crest of the spine of the scapula, lateral margin of the acromion, anterior border of lateral one-third of clavicle

Question 13

Innervation of trapezius?

Answer 13

Motor spinal part of accessory nerve (XI). Sensory (proprioception) anterior rami of C3 and C4

Question 14

Innervation of deltoid?

Answer 14

Axillary nerve (C5, C6)

Question 15

Innervation of levator scapulae

Answer 15

Branches directly from anterior rami of C3 and C4 spinal nerves and by branches (C5) from the dorsal scapular nerve

Question 16

Innervation of rhomboid minor and major?

Answer 16

Dorsal scapular nerve (C4, C5)

Question 17

Function of deltoid muscle?

Answer 17

Major abductor of arm (abducts arm beyond initial 15° done by supraspinatus); clavicular fibers assist in flexing the arm; posterior fibers assist in extending the arm

Question 18

Function of trapezius muscle

Answer 18

Powerful elevator of the scapula; rotates the scapula during abduction of humerus above horizontal; middle fibers retract scapula; lower fibers depress scapula

Question 19

Function of rhomboid major and minor?

Answer 19

Elevates and retracts the scapula

Question 20

Function of levator scapulae

Answer 20

Elevates the scapula

Question 21

What muscles make up the posterior scapula region?

Answer 21

The posterior scapular region occupies the posterior aspect of the scapula and is located deep to the trapezius and deltoid muscles. It contains four muscles, which pass between the scapula and proximal end of the humerus:
supraspinatus,
infraspinatus,
teres minor, and teres major muscles.

Question 22

Innervation of the long head of triceps brachii

Answer 22

Radial nerve (C6, C7, C8)

Question 23

Which ligaments are likely to be torn when the acromio-clavicular joint is dislocated?

Answer 23

Coracoclavicular ligaments – has 2 parts conoid and trapezoid
The joint capsule of the acromioclavicular joint and any ligamentous thickenings can also be torn

Question 24

What deformity will you be able to see following the injury? ( Pratheep has fallen from his skateboard hitting his shoulder hard against the ground. Pratheep is later diagnosed with a dislocated acromioclavicular joint.)

Answer 24

The distal end of the clavicle will sit superior to the acromion where it is observable and palpable

Question 25

Why is injury of the acromio-clavicular joint often called a “shoulder separation”.

Answer 25

The term shoulder separation is really a misnomer. It refers to the fact that the shoulder joint has separated from the supporting strut that is the clavicle. Separation can refer to a subluxation or dislocation of the joint.

Question 26

[Several weeks after surgical resection of the right axillary lymph nodes (performed for the staging and treatment of breast cancer), Mary’s husband noticed that her right scapula was sticking out more than the left.] Which nerve was damaged during the nodal resection?

Answer 26

Long thoracic nerve as it passes inferiorly through the axilla over the superficial surface of serratus anterior

Question 27

What is the abnormality commonly called and how would you test the function of the nerve during examination of the patient? [Several weeks after surgical resection of the right axillary lymph nodes (performed for the staging and treatment of breast cancer), Mary’s husband noticed that her right scapula was sticking out more than the left.]

Answer 27

Winging of the scapula. Patient faces a wall, places palms of hands on the wall, lock the arms in an extended position and then leans into the wall (almost like doing the first stage of press up into the wall). Serratus anterior contraction should prevent scapula winging.

Question 28

Why did the nerve damage cause the abnormal appearance of the scapula? [Several weeks after surgical resection of the right axillary lymph nodes (performed for the staging and treatment of breast cancer), Mary’s husband noticed that her right scapula was sticking out more than the left.]

Answer 28

The long thoracic nerve innervates serratus anterior which passes from ribs 1-8 in the mid axillary region, deep to the scapula to insert into the its medial border. It therefore helps prevent the medial scapula border from lifting away from the thorax when posterior force applied to an outstretched upper limb.

Question 29

What abnormalities of arm movements would also likely be present? [Several weeks after surgical resection of the right axillary lymph nodes (performed for the staging and treatment of breast cancer), Mary’s husband noticed that her right scapula was sticking out more than the left.]

Answer 29

What abnormalities of arm movements would also likely be present? Serratus anterior helps protract the scapula. It is therefore necessary to help patient reach out/punch (anteriorly) and can be involved in activities such as combing hair. It also helps stabilise the pectoral girdle, therefore instability may present.

Question 30

[Several weeks after surgical resection of the right axillary lymph nodes (performed for the staging and treatment of breast cancer), Mary’s husband noticed that her right scapula was sticking out more than the left.] How else might this nerve may be injured/become functionless?

Answer 30

Need to consider root of travel of the nerve. - Axillary surgery/trauma - Brachial plexus injury - Root of neck injury (posterior triangle)

Question 31

What are the surface markings of the lungs and fissures?

Answer 31

Lungs apex sits at a point ~2cm superior to the medial 1/3 of the clavicle (lung apex). The medial margin then descends retrosternally to the level of the 6th costal cartilage at which point the lower border courses around the thorax between the following points; 6th rib at the midclavicular line, 8th rib in the midaxillary line, 10th rib at the paravertebral line. The oblique fissure runs from T3 spinous process anterior inferiorly around the thoracic wall to the 6th costal cartilage 5-10cm lateral to the sternum. Can approximate posteriorly using the medial border of the scapula of an abducted upper limb. The horizontal fissure of right lung starts at the 4th costal cartilage at the sternum and passes horizontally posteriorly to intersect the oblique fissure in the axilla

Question 32

Give the borders of the triangle of auscultation.

Answer 32

Sits just medial to the inferior angle of the scapula. Borders= medial border of the scapula, latissimus dorsi & rhomboid major (trapezius is often used as an easier to identify alternative for rhomboid major)

Question 33

Over which ribs and intercostal space would you be placing the stethoscope when listening over the above space?

Answer 33

The triangle of auscultations sits over the 6th and 7th ribs and the 6th intercostal space. This approximates to the apical segment of the lower lobe

Question 34

How would damage to CN XI be apparent upon observation of the patient?

Answer 34

The shoulder on the affected side (left) would appear lower than the right (unaffected) due to the paralysis of trapezius. After several months there would be wasting of trapezius and loss of the curved contour of the lower lateral neck.

Question 35

Which muscle(s) are supplied by spinal root of CN XI and how would you test for signs of damage to their innervation?

Answer 35

Sternocleidomastoid. It turns the head to the opposite side. Ask patient to turn head and then repeat against resistance provided by the examiners hand

Question 36

Which muscles are responsible for abduction, flexion and lateral rotation of the glenohumeral joint?

Answer 36

Abduction: supraspinatus initiates, deltoid. Pectoral girdle rotation needed for full range of limb abduction Flexion: Biceps brachii, coracobrachialis, deltoid Lateral rotation: Infraspinatus, teres minor

Question 37

What is a bursa and where are they normally found in the body?

Answer 37

A bursa is a self-contained pocket of synovial fluid that sits in an area of wear.

Question 38

Describe the structure of the elbow joint and explain the location of the subcutaneous olecranon bursae.

Answer 38

The elbow is formed by the trochlea notch of the elbow articulating with the trochlea of the humerus, and the radial head articulating with the capitulum of the humerus. The olecranon is the protruberance of bone located on the posterior surface of the proximal ulna. The subcutaneous olecranon bursa sits under the skin over the bony olecranon.

Question 39

How would you manage subcutaneous olecranon bursitis?

Answer 39

Avoid the precipitating activity (patient education) Regular Icing & NSAIDS Do not sleep/lean on affected side Drainage & corticosteroid injection

Question 40

Boundries of the cubital fossa?

Answer 40

Superior boundary – Inter-epicondylar line Medial boundary formed by the lateral border of pronator teres Lateral boundary formed by the medial border of brachioradialis

Question 41

Which nearby neurovascular structures are at risk of damage when cannulating the cephalic vein as it passes over the anatomical snuffbox? What might be the consequence of damage to these structures?

Answer 41

Superficial branch of the radial nerve – damage would lead to sensory loss in the radial nerve distribution in the hand (ask the students where they would test for this) Radial artery – damage to the artery most likely to lead to a haematoma; more severe damage potentially could cause vasospasm and arterial insufficiency to distal regions, especially if there is inadequate collateral flow

Question 42

Describe the sensory innervation of the hand and state where you would test each main cutaneous nerve via a physical examination.

Answer 42

Palmar surface of lateral 3.5 digits (including associated palm) = median nerve Palmar and dorsal surface of medial 1.5 digits (including associated palm) = ulnar nerve Dorsal surface of lateral 3.5 digits = radial nerve

Question 43

Describe the course of the ulnar nerve from the medial humeral epicondyle to its termination in the hand.

Answer 43

Passes posterior to the medial humeral epicondyle, then into the anterior forearm to sit under the cover of flexor carpi ulnaris. It passes down a line from the medial epicondyle to a point just lateral to the pisiform bone.

Question 44

Explain the resting position of the hand following complete compression/ damage to the ulnar nerve at the elbow? Why is ulnar nerve damage at the wrist worse than damage at the elbow?

Answer 44

Elbow compression of the ulnar nerve would lead to an ulnar claw hand: - Clawing of digits 4 & 5. The students need to know that this is extension of the MCP and flexion of the corresponding IP joints. - The claw arises due to the loss of the interossei and lumbrical function on digits 4 & 5. These muscles normally pull on the extensor expansion whilst at the same time flexing the MCP joint. The muscles normally bring about a fine amount of MCP joint flexion which is able to counteract the strong pull of the long extensors. If this fine flexion is lost the long extensors pull the MCP into extension, and the consequent change in digit position leads to the long flexor (FDS) flexing the IP joints. The students should be aware that this is a resting position of the hand, the patient is not actively moving anything. Injury at the wrist produces worse symptoms since FDP to digits 4&5 will still be innervated by the ulnar nerve and can therefore pull digits 4&5 into an even tighter claw. This is known as the ulnar paradox (paradox as you would expect a more distal injury to result in less symptoms).

Question 45

What are the anatomical boundaries of the “Snuff Box”?

Answer 45

Ventro-lateral = abductor pollicis longus & extensor pollicis brevis Dorso-medial = Extensor pollicis longus Floor contains formed by the scaphoid and trapezium

Question 46

Describe the blood supply of the scaphoid bone.

Answer 46

Blood supply enters the distal part of the bone and passes proximally. This is because most of the proximal regions of the bone are covered in articular hyaline cartilage.

Question 47

What forms the axillary folds?

Answer 47

``` The axillary folds are formed by muscle covered in skin Anterior axillary fold Pectoralis major & minor Posterior axillary fold Latissimus dorsi & teres major ```

Question 48

What is the significance of the axilla?

Answer 48

Bordered by pectoral girdle muscles and thoracic cage Neurovascular supply to upper limb runs through this region Filled with fat Tail of breast extends into region Contains important lymph node groups

Question 49

What sites are drained by the axillary lymph nodes?

Answer 49

- Anterior thoracic wall & breast - Posterior thoracic wall - Upper limb

Question 50

Which nerve roots are damaged in Erb's palsy? What is the consequence of this injury?

Answer 50

C5 & C6 Upper Root/Trunk Damage Results in ‘waiters tip’ appearance of upper limb Limb = Medially rotated, pronated, hangs limp

Question 51

What type of injury leads to Erb's palsy?

Answer 51

Forced separation of neck from shoulder Stab wound to neck during childbirth

Question 52

Which nerve roots are damaged in Klumpke's palsy? What is the consequence of this injury?

Answer 52

C8 & T1 Lower Root Damage/Compression Upward traction of limb claw hand deformity

Question 53

What type of injury leads to Klumpke's palsy?

Answer 53

Cancer at lung apex Compression via cervical rib

Question 54

Which nerve passes behind the medial epicondyle?

Answer 54

Ulnar nerve ‘funny bone’ runs behind here; damaged by fracture; you can palpate it here

Question 55

What surrounds the head of the radius?

Answer 55

Annular ligament

Question 56

What is the anconeus triangle? and what are the borders?

Answer 56

``` Anconeus triangle Region for elbow injection/aspiration - Radial head - Lateral epicondyle - Olecranon ```

Question 57

What surrounds the elbow joint? Where is this structure weakest?

Answer 57

A fibrous capsule surrounds the elbow joint - weaker anteriorly & posteriorly

Question 58

MCL and LCL at elbow? What are they? Function?

Answer 58

MCL Resists Abduction/Valgus LCL Resists Adduction/Varus

Question 59

What is the interosseus membrane an example of?

Answer 59

Fibrous joint between radius and ulna; Note the direction of its fibres for force transmission

Question 60

What are the features of the Proximal radioulnar joint?

Answer 60

Annular ligament encircles the radial head forming a synovial pivot joint permitting pronation & supination; Can be dislocated especially in children (nursemaid’s elbow)

Question 61

What kind of joint is the distal radioulnar joint?

Answer 61

Synovial pivot joint

Question 62

What structures are separated by the articular disc?

Answer 62

Separates ulna from proximal carpal bones of wrist joint

Question 63

Which muscles comprise of the first anterior forearm layer?

Answer 63

Forearm pronator and abductor/adductor of the wrist. Pronator teres [median] Flexor carpi radialis [median] ABDUCTOR Flexor carpi ulnaris [ulnar] ADDUCTOR Palmaris longus [median]

Question 64

Which muscles/ligaments comprise the second anterior forearm layer?

Answer 64

Powerful flexor of the digits Flexor Digitorum Superficialis Finger flexor to PIP. Note attachments to radius and ulna Median n. Transverse carpal ligament Forms the roof of the carpal tunnel

Question 65

Which muscles/ligaments comprise the third anterior forearm layer?

Answer 65

Pronator and powerful flexors of the digits and thumb Flexor Pollicis Longus: Thumb flexor to the DIP Median n. Flexor Digitorum Profundus: Finger flexor to the DIP ½ Median & ½ Ulnar n. Pronator quadratus: Forearm pronator Median n.

Question 66

In the anterior forearm, everything is median nerve supplied except:

Answer 66

- Flexor carpi ulnaris - Flexor digitorum profundus to digits 4 & 5 (the part of FDP muscle on the ulnar side)

Question 67

What is the lateral epicondyle an attachment for?

Answer 67

Forms a common origin for the tendons ED, ECRB, EDM & ECU. Regional inflammation & pain/tenderness can indicate lateral epicondylitisis (Tennis elbow)

Question 68

Where does the radial nerve pass wrt the elbow?

Answer 68

Passes anterior to the elbow and lateral to biceps tendon. Deep posterior interosseous branch then passes close to radial neck

Question 69

Where does the ulnar nerve pass wrt the elbow?

Answer 69

Passes through the cubital tunnel & behind the medial epicondyle then enters the anterior forearm; potential point of compression