Workbook questions 5 & 6 Flashcards
Where is the axis of rotation in the movements of pronation and supination?
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.
Explain what is a “pulled elbow” and why does it happen more often in children?
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.
Why is supination a more powerful movement than pronation?
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).
What group of muscles arise (originate) from the lateral epicondyle?
The extensor-supinator muscles arise by a common extensor tendon from the lateral epicondyle of the humerus.
What bony structures can be palpated around the elbow?
Lateral & medial epicondyle of the humerus, olecranon process of the ulna, &
head of the radius.
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.
Elbow joint – flexion & extension
Proximal radio-ulnar joint – pronation & supination
A 40-year old tennis player - What do you think is the cause of localised tenderness at the lateral epicondyle?
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.
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
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
Which structures form the boundaries, floor and roof of the “anatomical snuff box”?
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.
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?
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.
Which muscles would cause medial deviation (or adduction) and lateral deviation (or abduction) of the wrist?
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.
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..
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.
Define Kyphosis
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.
Define Scoliosis
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.
Define lordosis
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.
Explain the cause of diminution of height and loss of curvature in old age?
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
What anatomical abnormalities occur in the vertebral column in spina bifida?
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.
In general what factors contribute to the stability and mobility of the vertebral column?
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.
Which movements are possible in the cervical, thoracic and lumbar regions and state why?
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.
Why should the cervical vertebrae be prone to dislocation in whiplash injuries?
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.
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?
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.
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?
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)
What do you understand by the terms “intrinsic” and “extrinsic” muscles of the hand?
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.
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?
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.
