Workbook questions 5 & 6

Question 1

Where is the axis of rotation in the movements of pronation and supination?

Answer 1

The axis passes longitudinally along the head of the radius (proximally) and through the distal radio-ulnar joint at the wrist. During pronation and supination the radius rotates over the ulna; movements take place at the proximal and distal radio-ulnar joints.

Question 2

Explain what is a “pulled elbow” and why does it happen more often in children?

Answer 2

A “pulled elbow” is partial (subluxation) or complete separation (dislocation) of the articulating surfaces of the bones forming the proximal radio-ulnar joint. The injury results when a person is lifted by the upper limb with the forearm in a pronated position. The pulling of the upper limb tears the distal attachment of the annular ligament (surrounding the radial head) where it is loosely attached to the neck of the radius. The radial head moves down (distally) and out of the torn ligament. The injury is more common in children because the radial head and the annular ligament has not fully formed.

Question 3

Why is supination a more powerful movement than pronation?

Answer 3

Supination is a more powerful movement than pronation because of the strength of the biceps brachii is greater than the muscles of pronation (pronator teres and pronator quadratus; consider cross-sectional area of the muscles).

Question 4

What group of muscles arise (originate) from the lateral epicondyle?

Answer 4

The extensor-supinator muscles arise by a common extensor tendon from the lateral epicondyle of the humerus.

Question 5

What bony structures can be palpated around the elbow?

Answer 5

Lateral & medial epicondyle of the humerus, olecranon process of the ulna, &
head of the radius.

Question 6

A 40-year old tennis player saw his GP with pain in his right elbow. The doctor examined the movements of which joints? State the movements examined.

Answer 6

Elbow joint – flexion & extension

Proximal radio-ulnar joint – pronation & supination

Question 7

A 40-year old tennis player - What do you think is the cause of localised tenderness at the lateral epicondyle?

Answer 7

Elbow tendonitis (also called “tennis elbow”) – is a painful condition that may follow repetitive use of extensor muscles of the forearm. This produces inflammation of the periosteum of the lateral epicondyle (lateral epicondylitis) and the common extensor attachment of muscles.

Question 8

Now consider the common flexor origin of the medial epicondyle. Name two muscles who have their origin here that are supplied by the median nerve or by the ulnar nerve. (3 marks

Answer 8

Median nerve – Pronator teres, flexor carpi radialis, palmaris longus, flexor digitorum superficialis

Ulnar nerve- flexor carpi ulnaris (part)

N.B. Flexor digitorum profundus does not have its proximal attachment on the medial epicondyle. Unusually, its medial half is innervated by the ulnar nerve and lateral half by the median nerve.
Detailed knowledge of origin and insertion will not be required in assessment but general knowledge of location, such as this, will be required

Question 9

Which structures form the boundaries, floor and roof of the “anatomical snuff box”?

Answer 9

The boundaries of the anatomical snuff box are made more visible when the dorsum of the hand is examined with the wrist and digits extended against resistance. The medial boundary is formed by the tendon of extensor pollicis longus muscle while the lateral boundary is formed by the tendons of abductor pollicis longus and extensor pollicis brevis. The floor is formed by the scaphoid bone while the roof is formed by the skin.
Its clinical significance lies in the fact that the scaphoid bone is easily palpable in its floor and the pulsations of the radial artery can be felt by pushing the tip of a finger into the box. Fracture or bruising of the scaphoid will result in tenderness felt in the anatomical snuff box.

Question 10

A young woman falls on the outstretched hand and complains of pain deep in the “anatomical snuff box” on palpation. Explain fully why you should x-ray her wrist at the time of injury and four weeks later?

Answer 10

To check whether the scaphoid bone has been fractured or not. The fracture may affect the healing of the bone because of disrupted blood supply. The blood supply to the scaphoid is via the radial artery and enters the bone distally. An x-ray four weeks later will show whether or not proximal section of bone has undergone avascular necrosis, hence, if the blood supply has been maintained. The proximal segment will look less opaque if it is beginning to be resorbed.

Question 11

Which muscles would cause medial deviation (or adduction) and lateral deviation (or abduction) of the wrist?

Answer 11

Flexor and extensor carpi ulnaris cause adduction (medial or ulnar deviation) of the wrist. Flexor carpi radialis, extensor carpi radialis longus & brevis cause abduction (lateral or radial deviation) of the wrist.

Question 12

Explain why it is difficult to form a fist following radial nerve lesion. Hint: Flex the wrist fully whilst trying to form a tight fist..

Answer 12

In nerve injuries (e.g. radial nerve) which result in a “wrist drop” due to paralysis of the extensor muscles of the forearm, it is difficult to grip firmly because of the unopposed action of the flexors.

Question 13

Define Kyphosis

Answer 13

Kyphosis is an exaggeration of the posterior (kyphotic) curvature of the vertebral column (spine) in the thoracic region (humpback or dowager’s hump of osteoporosis); abnormality can result from erosion of the anterior part of one or more vertebrae and its progression leads to vertebral collapse and overall loss of height.

Question 14

Define Scoliosis

Answer 14

Scoliosis is a lateral curvature of the vertebral column (spine);
asymmetric weakness of the intrinsic back muscles, failure of half a vertebra to develop and a difference in the length of the lower limbs cause scoliosis.

Question 15

Define lordosis

Answer 15

Lordosis is an exaggeration of the anterior (lordotic) curvature of the vertebral column in the lumbar region;
may be associated with weakened trunk (anterolateral abdominal wall) musculature. In pregnancy, women develop a temporary lordosis to compensate for alterations to their lines of gravity.

Question 16

Explain the cause of diminution of height and loss of curvature in old age?

Answer 16

The intervertebral discs constitute approximately a quarter of the length of the vertebral column as well as its secondary curvatures (vis-à-vis the morphology of the discs in the lumbar region). With increasing age, the annulus fibrosis of the intervertebral discs begin to undergo degeneration (because of wear and tear). The nucleus pulposus loses its turgor and becomes thinner because of dehydration and degeneration (failure of imbibition). These degenerative processes account for some loss of height. Disc atrophy return the curvature of the spine to that C-shape of the newborn. Other changes (see above) may also contribute to decrease in height and lead to loss of curvature

Question 17

What anatomical abnormalities occur in the vertebral column in spina bifida?

Answer 17

A common congenital anomaly of the vertebral column in which the laminae of the lower lumbar vertebrae (most commonly affected is L5) and upper sacral vertebra (S1) fail to develop normally and fuse. In extreme situations, the spinal nerves or even the spinal cord protrude(s) backward out of the defect in the posterior midline of the vertebral column.

Question 18

In general what factors contribute to the stability and mobility of the vertebral column?

Answer 18

The normal range of movement of the vertebral column is limited by the thickness and compressibility of the intervertebral discs, the shape and orientation of the vertebral joints, resistance of the back muscles and ligaments.

Question 19

Which movements are possible in the cervical, thoracic and lumbar regions and state why?

Answer 19

Movements of the vertebral column are freer in the cervical and lumbar region than elsewhere. The thoracic region is relatively stable because of its connection with the sternum via the ribs and costal cartilages. Flexion is greatest in the cervical region and is non-existent in the thoracic region. Lateral bending is greatest in the cervical and lumbar regions and is restricted in the thoracic region by the ribs. Extension is most marked in the lumbar region. Flexion, extension and lateral bending of the vertebral column involve compression of the discs at one surface and stretching at the other. Flexion, extension and lateral bending and rotation of the neck are freer because of the thin discs, loose articular capsules and almost horizontal plane of the articular processes.

Question 20

Why should the cervical vertebrae be prone to dislocation in whiplash injuries?

Answer 20

The ligaments connecting the vertebrae are short and thin. Because of the
mobility of the cervical spine (for reasons see above), in whiplash injuries sudden forceful flexion and extension may result in tearing the thin connecting ligaments and causing the vertebrae to dislocate anteriorly or posteriorly.

Question 21

A patient with prolapsed intervertebral discs at L4/L5 and L5/S1 complains of sciatica. Where will the pain be worst, and which dermatomes will you examine to test for loss of sensation?

Answer 21

Pain in sciatica is in the lower back and hip radiating down the back of the thigh into the leg.

Dermatomes L5 (anterolateral aspect of the leg and mid-sole region) & S1 (lateral aspect of the lower leg from just above the lateral malleolus extending into the foot involving the fifth digit on the dorsal and ventral aspects), respectively.

Question 22

Superficial lacerations at the wrist would result in loss of sensory function in the palm of the hand only. Can you explain the reason for this loss?

Answer 22

At the wrist, the median nerve becomes superficial in the midline and gives off a palmar cutaneous branch which supplies the skin of the midpalm.

(Palmar cutaneous branch of the ulnar nerve may also be affected leading to further loss of sensation over the medial palm)

Question 23

What do you understand by the terms “intrinsic” and “extrinsic” muscles of the hand?

Answer 23

Intrinsic muscles of the hand are those muscles that are found within the hand (originate & insert) and are responsible of movements of the thumb and fingers. Extrinsic muscles of the hand are those muscles that originate in the forearm and insert into structures in the hand to allow movements of the thumb and fingers.

Question 24

Damage to the ulnar nerve at the wrist may result in a “claw hand”. Why is the clawing pronounced in the fourth and fifth digit?

Answer 24

This is because of the paralysis of the 3rd and 4th lumbrical muscles acting on the 4th (ring finger) and 5th (little finger) digits; these two lumbrical are supplied by the ulnar nerve. The lumbrical muscles flex the digits at the metacarpophalangeal joints (MPJ) and extend the digits at the interphalangeal joints (IPJ) via the dorsal digital expansion.

Paralysis of the lumbricals will result in the MCPJoints becoming hyperextended and the IPJoints becoming flexed; this deformity is obvious because the first and second lumbricals (acting on the index & middle fingers) supplied by the median nerve are not paralysed.

Question 25

What is the motor loss, in general terms, in the hand as a consequence of damage to the ulnar and median nerve at the wrist?

Answer 25

Damage to the ulnar nerve will result in the loss of motor supply to the hypothenar muscles, 3rd & 4th lumbricals, all the interossei (dorsal & palmar interossei) muscles and the adductor pollicis muscle.

Damage to the median nerve will result in the loss of motor supply to the thenar muscles and the 1st & 2nd lumbricals.

Question 26

Which vital function of the thumb will be affected as a result of damage to the median nerve at the wrist? Explain.

Answer 26

Loss of accurate opposition of the thumb to other fingers. This is a serious disability because along with loss of cutaneous sensation of the thumb, the adjacent 2 & ½ fingers and the radial 2/3rd of the skin of the palm of the hand. This will prevent accurate and delicate adjustments that the hand makes in response to tactile stimuli and holding e.g., a pencil

Question 27

What common action do the lumbricals and interossei muscles perform and at what joints? (2 X 1 mark) Why do you need them to be able to write properly?

Answer 27

The lumbricals & the interossei muscles flex the fingers at the MP joints and extend the fingers at the IP joints. Writing involves holding the pen/pencil between the flexed MP joints of the thumb & 1st & 2nd fingers and the extended IP joints of the thumb & 1st finger and partially extended (IP joints) of the ring finger.

Question 28

Penetrating injuries to the palm and digits of the hand may result in infection of the osteofibrous tunnels. What are the likely consequences of these injuries? (consider the arrangement of the synovial sheath)

Answer 28

Inflammation of the tendon and its synovial sheath (tenosynovitis) may cause the digit to swell and result in painful movement. The 1st, 2nd and 3rd fingers normally have separate synovial sheaths and inflammation is confined to the affected digit; the synovial tendon sheath of the thumb and the 4th finger (little finger) are often continuous with the common flexor synovial sheath around the wrist and thus inflammation may spread to the common sheath. Rupture of affected sheaths may allow spread into the midpalmar space.

Question 29

How might a swelling proximal to the wrist joint be connected with infection in the tip of the thumb? (again consider the synovial sheath)

Answer 29

The common synovial sheath is continuous with the flexor sheath of the thumb. Infection from the tip of the thumb may travel down the sheath and affect the wrist region.

Question 30

Draw a diagram of the palmar and dorsal aspect of the hand, label the shaded area of cutaneous distribution of the ulnar, median and radial nerve. You may also wish to give an anatomical description of these areas and indicate the most reliable site for testing each nerve.

Answer 30

The ulnar nerve supplies the skin of the palm over the hypothenar eminence,
the palmar aspect of the skin over the little finger & ulnar side of the ring finger.
The median nerve supplies the midpalmar skin(via the palmar cutaneous nerve
of the median nerve before the main nerve enters the carpal tunnel), the palmar
skin over the thenar eminence and the palmar aspects of the skin of the thumb,
index and middle fingers and the radial side of the ring finger.

On the dorsal aspect of the hand, the ulnar nerve innervates the ulnar side of the dorsum of hand extending into the dorsal skin of the little finger and ulnar side of the ring finger. The median nerve innervates the dorsal aspect of the skin of the thumb, the index, middle and radial side of the ring fingers extending beyond the nail bed.
The radial nerve innervates the remainder of the skin on the dorsal aspect, The most reliable areas for testing sensation if the radial nerve is the a small area of the first interdigital webspace (between the thumb and index finger).
Some books give the anatomical snuff box; this is not an adequate answer and in clinical examination would not be acceptable.

Question 31

What methods are used in clinical examination to test for areas of sensory loss and different modalities of sensation (e.g. touch, pain, temperature)?

Answer 31

• Light touch is assessed by a wisp of cotton wool
• Pain is assessed by pinprick sensations and provides a more reliable map of
  sensory loss as pain fibres do not tend to overlap with the with the next
  dermatomes as touch fibres tend to.
• Deep pain can be assessed by a pressure squeeze test.
• Temperature can be assessed by touching with a cold metal object such as
  a tuning fork.

Question 32

Can you explain why the nerve supply to the nail bed is as what you have indicated on the diagram above?

Answer 32

The nails & nail bed regions begin to form on the palmar aspect of the hand and “carry” their nerve supply as they “migrate” to the back of the hand during the development of the hand.

Question 33

On the diagram (palmar aspect of the wrist), label the radius, ulna and the carpal bones. Mark the attachments of the flexor retinaculum. (4 X ½ marks, you need to know these attachments)

Answer 33

The flexor retinaculum is attached to the medially to the pisiform and the hook of the hamate bones and laterally to (the tubercle of) the scaphoid and the trapezium bones.

Question 34

What structures form the floor, sidewalls and roof of the carpal tunnel?

Answer 34

Floor – proximal row of carpal bones (scaphoid, lunate & triquetrum; distal row of carpal bones (trapezium, trapezoid, capitate & hamate);

roof – the flexor retinaculum or the transverse carpal ligament;

side walls – concavity of the carpal bones.

Question 35

What structures pass through the tunnel?

Answer 35

The four tendons of flexor digitorum superficialis muscle, the four tendons of flexor digitorum profundus muscle, tendon of flexor pollicis longus muscle and the median nerve.

Question 36

Pressing over her right carpal tunnel brought on her pain and tingling in her thumb and fingers except the little finger. Why is there no tingling in the little finger?

Answer 36

The sensory supply to the little finger is via the cutaneous (superficial) branch of the ulnar nerve which passes over the flexor retinaculum on its medial aspect.

Question 37

In carpal tunnel syndrome - Explain why no tingling would be felt in the palm of the hand.

Answer 37

The skin in the palm of the hand is supplied by the ulnar nerve (over the hypothenar eminence - muscles) and by the palmar cutaneous branch of the median nerve in the palm (except the skin over the thenar eminence – muscles supplied by the median nerve proper after passing through the carpal tunnel.

Question 38

List four causes of the carpal tunnel syndrome and explain why the GP asked
about her menstrual history

Answer 38

Causes of carpal tunnel syndrome (increased pressure within the carpal tunnel); Tenosynovitis (thickening of the synovium), repetitive trauma (compression forces & stretching), oedema, fractures, dislocations, inherited small bone structures. Risk factors – occupation involving repetitive tasks, diabetes, rheumatoid arthritis, hypothyroidism, PREGNANCY, menopause, obesity