Other Stuff Flashcards
(151 cards)
0
Q
Describe a synovial joint:
3 Defining features
Accessory structures
Types
A
Protective capsule, surrounding joint
Synovial membrane secreting Synovial fluid
Articular surfaces covered with hyaline cartilage
Ligaments (intrinsic/extrinsic)
Menisci
Fibrous capsule / muscle (strengthen joint)
Plane (gliding/sliding) (e.g. Acromioclavicular joint)
Hinge (flexion/extension) (e.g. Elbow)
Saddle (concave & convex: fwd/bkwd, side-side) (e.g. 1st CPMJ)
Ball & socket (several axis) (e.g. Shoulder, hip)
Condyloid (flex/ext, add/abd, circumduction) (e.g. MCPJ i.e. Knuckles)
Pivot (rotation) (e.g. Proximal radioulnar joint)
1
Q
Classification of joints (according to tissue that lies between them)
A
Synovial
Cartilaginous
Fibrous
2
Q
Describe a cartilaginous joint:
2 broad categories For each describe: Another name Connecting medium Where it is found
A
Primary cartilaginous:
Synchondrosis
Hyaline
Mostly in growth, except btw 1st rib & sternum
Secondary cartilaginous:
Symphysis
Fibrocartilage
Throughout body e.g. Intervertebral disc, pubic symphysis
3
Q
Describe a fibrous joint:
Type of connective tissue
Where it is found
A
Fibrous CT
E.g. Btw plates of skull (sutures),
gomphosis (peg-like bones of teeth into socket),
syndesmosis (flattened sheet of CT connecting ulna & radius)
4
Q
Concerning functional classification of joints:
Define the following & state which type of joint each is involved in:
Diarthrosis
Amphiarthrosis
Synarthrosis
A
Diarthrosis:
Allow greatest ROM
Synovial joints
Amphiarthrosis:
allows for slight mobility
cartilaginous joints
Synarthrosis:
Fixed/immovable
Fibrous joints
5
Q
Describe the 7 types of arrangement of skeletal muscle
Give an example of each
A
Circular (e.g. Orbicularis oris) Convergent (e.g. Pec major) Parallel (e.g. Sartorius) Unipennate (e.g. Extensor digitorum longus) Multipennate (e.g. Deltoid) Bipennate (e.g. Rectus femoris) Fusiform (e.g. Biceps brachii)
6
Q
Describe the 3 classes of levers in the body
A
First class lever:
Like a seesaw
Most efficient
E.g. Neck/skull
Second class lever:
Like a whelbarrow
Less efficient
E.g. Toes/foot
Third class lever:
Like a fishing rod
Least efficient
Most muscles in body
7
Q
Name the 4 muscle groups
A
Agonists: prime mover
Antagonists: oppose prime mover
Synergists: assist prime mover
Fixators: stabilise prime mover
8
Q
Name the 4 types of muscle fibres
A
I Slow twitch
IIa Fast twitch (oxidative)
IIb Fast twitch (glucolytic)
Proprioceptors
9
Q
Can cartilage be converted into bone? Explain.
A
No.
Cartilage can be replaced by bone. Cartilage
(cartilage matrix) can become calcified thus restricting
nutrient and gaseous supply to chondrocytes;
chondrocytes thus die. Osseous tissue can be laid on the
surface of the calcified matrix, eventually replacing all
cartilage by bone.
10
Q
What are the factors that restrict movement at synovial joints?
A
Tension exerted by ligaments of the articular cartilage (e.g. iliofemoral ligament of
hip).
Muscle tension (thigh difficult to raise when knee is straight – stretched hamstrings)
Interference by other structures. Stability at joints is also related to the depth of bony
articulations.
11
Q
State the mechanical functions of bones
A
Provide the rigid framework that supports the body.
Protect vulnerable internal organs (e.g. brain, heart, lungs,
etc.).
Make body movements possible by providing anchoring
points for muscles and by acting as levers at the joints.
12
Q
What factors are responsible for the appearance of
tuberosities, tubercles, ridges and grooves on a
typical long bone?
A
Tuberosities, tubercles and ridges – mechanical forces
resulting from attachment of muscles, tendons and
ligaments to bone.
Grooves – pressures from adjacent structures e.g. nerves
and blood vessels
13
Q
What is the basic difference between intramembranous and endochondral ossification?
A
Intramembranous – develops directly from mesenchymal tissue
Endochondral – develops by replacing hyaline cartilage model.
14
Q
What are the 3 types of bone cells & their function?
A
Osteoblasts are bone-forming cells (secrete collagen to form a matrix which is
calcified)
Osteocytes are former osteoblast cells that become encased in the bone
matrix, forming tight junctions with each other across the matrix.
Osteoclasts are bone-breaking cells (resorb bone).
15
Q
why is hypocalcaemia or hypercalcaemia dangerous?
A
(To maintain homeostasis, bones help to regulate the amount and consistency of
extracellular fluid by adding calcium to it or taking calcium out of it.) Small decreases
of calcium in plasma and extracellular fluid (hypocalcaemia) can cause the nervous
system to become more excitable because of increased neuronal membrane
permeability with resultant muscular spasm. Too much calcium (hypercalcaemia) in
body fluids depresses the nervous system and causes muscles to become sluggish
and weak because the effects of calcium on muscles’ plasma membranes. Bones
represent a calcium store for homeostasis.
16
Q
What is the action of PTH & Calcitonin on bone?
What stimulates their release?
A
Parathyroid hormone (PTH) and calcitonin (CT) have direct effects on bones. PTH
released from the parathyroid glands in response to low calcium levels in the blood
stimulates the uptake of calcium from bone, kidneys and the intestinal tract to return
calcium levels to normal. PTH increases the number and activity of osteoclasts in
bone to increase calcium (and phosphate) resorption from bone and stimulate
release of the minerals into blood.
C
T is released from specific thyroid cells (parafollicular cells) in response to elevated
calcium levels in the blood. CT causes calcium levels to be lowered by inhibiting
osteoclastic activity in bone; it also favours calcium uptake by bone, promoting bone
formation and decreasing blood calcium levels.
PTH increases blood calcium, while CT lowers it.
(Human growth hormone, thyroid hormones, sex hormones, adrenal cortical
hormones and vitamins A,C and D are also important in bone function.
17
Q
How does nutritional deficiency in the following affect bone:
Calcium/phosphorous
Vitamin A
Vitamin C
A
State how nutritional deficiency of the following compounds may affect bone.
i) Calcium / phosphorous (2 X ½ marks)
Proper nutrition (calcium and phosphorus constitute almost half the content of bone)
is essential for normal bone development and maintenance; thus their deficiency
causes bones to become brittle.
ii) Vitamin A (2 X ½ marks)
Deficiency in vitamin A may cause an imbalance in the ratio of osteoblasts and osteoclasts, thereby slowing the growth rate.
iii) Vitamin C (2 X ½ marks)
Low levels of vitamin C inhibit growth by causing an insufficient production of
collagen and bone matrix, a condition that delays the healing of broken bones.
18
Q
Explain the cause of Oesteomalacia in adults/rickets in children
A
If the diet is too low in vitamin D, the normal ossification process at the epiphyseal
growth plate is affected and the bones may easily become deformed. Osteomalacia
and rickets are defects skeletal resulting from vitamin D deficiency. This leads to
widening of the epiphyseal plates, increased number of cartilage cells, wide osteoid
seams and decrease in linear growth. Rickets is a childhood disease caused by
insufficient mineralisation.
In children with highly pigmented skin and others whose body surfaces are not
exposed to sunlight, absorption of ultra-violet rays is markedly affected; ultra-violet
rays are involved in vitamin D formation; skeletal deformities such as bowed legs,
knock-knees, etc. are common. Osteomalacia leads to demineralisation, an
excessive loss of calcium and phosphorus; this condition can be reversed with large
doses of vitamin D.
19
Q
How do bisphosphonates & calcitonin help those with oesteoporosis?
A
Both inhibit osteoclast activity. Calcitonin can also stimulate osteoblast activity and
favours calcium uptake into bone.
20
Q
What process, within the muscle fibre, causes skeletal muscle relaxation?
A
The active transport of calcium ions back into the sarcoplasmic reticulum.
21
Q
halothane (general anaesthetic) can cause an abnormal rise in cytoplasmic calcium within skeletal muscle fibres. Suggest two ways by which this could occur. (Hint, consider the role of sarcoplasmic reticulum on how
changes could cause a rise in cytoplasmic calcium).
A
i. Entry of calcium from the extracellular fluid
ii. Blocking the re-uptake of calcium back into the sarcoplasmic reticulum
after its release
iii. Increasing the release of calcium from the sarcoplasmic reticulum
The latter is the actual mechanism and is caused by a faulty calcium
channel in the sarcoplasmic reticulum through which the calcium is released.
Dantrolene is a directly acting skeletal muscle relaxant that blocks the release
of calcium from intracellular stores.
22
Q
How does an increase in intracellular calcium produce
symptoms of muscle rigidity?
A
An increase in intracellular calcium activates the crossbridge cycle promoting
contraction. The sustained release of calcium counteracts the process of re-
uptake of calcium back into intracellular stores necessary for relaxation.
23
Q
List clinical signs of a large increase in body metabolism.
A
Rise in body temp, Fall in blood oxygen, rise in blood carbon dioxide, fall in blood pH,
tachycardia, increased ventilation, etc. Blood vessel compression due
to muscular rigidity impairs blood flow and contributes to the changes
in blood gas levels.
24
Name the structures are contained within the axillary sheath in the axilla
Axillary artery, axillary vein and cords & branches of the brachial plexus.
25
In a female patient, explain why would you be concerned about enlargement
of lymph nodes in the axilla?
The axillary lymph nodes receive lymph from the breast; in cancer of the breast,
cancerous cells may enter the lymph vessels and pass to the axilla lymph and may
produce enlargement of axillary lymph nodes.
26
Name the nerves that supply flexor muscles of the arm and the forearm.
Musculocutaneous, radial, median and ulnar
27
The lateral, medial and posterior cords of the brachial plexus are named with
respect to an important blood vessel. Name this vessel.
Axillary artery
28
Which important blood vein lies immediately posterior
| to the sternoclavicular joint?
Brachiocepalic vein
29
Explain what would happen to the position of the arm and clavicular
fragments in the event of a fracture of the clavicle?
The clavicle acts as a strut (rigid support) from which the scapula and the upper limb
are suspended and keeps them away from the thorax (allowing the arm to have
maximum freedom of motion).
W
hen the clavicle fractures, the sternocleiodomastoid muscle elevates the medial
segment; because the trapezius muscle is unable to hold the lateral segment up and
because of the weight of the upper limb, the shoulder drops and the arm is pulled
medially by the adductor muscles of the arm.
30
Define the following terms:
Amelia
Meromelia
polydactyly
Amelia: A complete absence of a limb or limbs
Meromelia: Partial absence of a limb or limbs
polydactyly:
Supernumery (extra) fingers or toes; often an extra digit is incompletely formed and lacks proper muscle fixation. In the hand, the extra digit is either on the ulnar or radial side rather than central; in the foot it on the fibular side.
31
Explain syndactyly?
What is the structural difference between “cutaneous syndactyly” and
“osseous syndactyly”?
Fusion of fingers or toes; more frequent in the foot than in the hand. results from a lack of differentiation between two or more digits. Normally the mesenchyme in the periphery of the hand and foot plates condenses to form the primordial of the fingers and toes and the thinner tissue between them breaks down. In some cases, there is also fusion of the bones.
most frequently observed between the third and fourth fingers and second and third toes.
Cutaneous syndactyly:- Webbing of the skin between the fingers and toes results from failure of this tissue breakdown to occur.
Osseous syndactyly: fusion of the bones.
32
What is the structural defect underlying congenital dislocation of the hip (CHD)?
CHD is associated with breech presentation (i.e. buttocks rather than head delivered first). Speculate on why this might be so?
Underdevelopment of acetabulum and head of femur.
Breech presentation may place undue pressure on the developing hip joint: fails to complete normal development.
33
What is the function of the apical ectodermal ridge (AER)?
Explain what happens if the AER is disrupted and give one mechanism
causing its disruption.
Stimulates outgrowth of limb and maintains undifferentiated state in mesenchyme immediately underlying it.
No limb growth/ shortened limbs; interference affecting blood vessels of AER
34
Where does the brachial artery lie in relation to the median nerve in the upper arm and in the cubital fossa?
In the upper arm, it lies medial to the median nerve
| in the cubital fossa, it lies lateral to it
35
Which structure lies immediately anterior to the brachial artery and the median nerve in the cubital fossa?
What is its function?
Bicipital aponeurosis:
comprises collagen fibres radiating from the distal part of the biceps tendon passes obliquely across the cubital fossa and merges with the fascia covering the flexor muscles in the medial
side of the forearm.
provides some protection to the brachial artery & the median nerve.
36
Where in the elbow region can you normally palpate the ulnar nerve against the humerus?
The ulnar nerve at the elbow passes behind the medial epicondyle of the humerus. It lies in close proximity to the bone surface (& grooving it). It enters the forearm passing through a structure called the “cubital tunnel” formed by the tendinous arch joining the humeral and ulnar heads of the attachment of flexor carpi ulnaris.
Here the nerve could get compressed to produce symptoms/signs of the "cubital tunnel syndrome”.
37
What is subcutaneous olecranon bursitis and how does it occur.
The bursa lying between the skin and the olecranon process of the ulna becomes inflamed and produces a swelling due to excessive friction. (also known as “student’s elbow, miner’s elbow).
The bursa may become infected and the skin area superficial to it may become inflamed.
38
State three specific factors contribute to the stability of the shoulder joint?
The tone of the rotator cuff muscles:'coracobrachialis, short head of
biceps and long head of triceps assist the deltoid in resisting downward dislocation of the joint.
Capsular and extracapsular ligaments.
Glenoid labrum helps to deepen the glenoid fossa (cavity).
39
Why does the humeral head dislocate so easily?
| What is the usual direction of dislocation and why?
The glenoid fossa (cavity) is relatively shallow; it accepts a little more than a third of the humeral head.
Although the joint is strengthened on its superior, anterior and posterior aspects, it is weak on its inferior aspect. Hence, the head of the humerus usually dislocates inferiorly, but ends up as an anterior (subcoracoid location) due to the pull of muscles , i.e. anterior-inferior dislocation.
40
What is the “coraco-acromial arch” and what is its role at the shoulder when falling down on an outstretched hand?
an extrinsic, protective osseoligamentous structure formed by the smooth inferior aspect of the acromion and the coracoid process of the scapula with the coracoacromial ligament spanning between them. It forms a protective arch that overlies the head of the humerus, preventing its superior displacement from the glenoid cavity of the scapula.
41
Which nerve and blood vessels are at risk during the inferior displacement of the humeral head from the glenoid cavity (as in anterior-inferior dislocation of the shoulder?)
Axillary (circumflex) nerve and circumflex humeral arteries
42
How would you determine the integrity of the above nerve in a patient with a dislocated shoulder? What would you not do and why?
Test for sensation in the “regimental badge area” on the upper lateral part of the arm (area supplied by the cutaneous branch of the axillary nerve).
Do not test motor function, as this would lead to more damage.
43
In injuries of the shoulder joint, the humerus may fracture at its “surgical neck”. Where is the “anatomical neck” of the humerus and give one anatomical significance of it?
The anatomical neck is formed by the groove circumscribing and separating the head from the greater and lesser tubercles.
Significance:
• The articular capsule of the joint is attached nearby.
• The anatomical neck also marks the region of the epiphyseal growth plate during the growth in length of the humerus.
44
Describe two effects of a torn supraspinatus tendon as shown in clinical examination of the shoulder joint?
Failure of initiation of abduction in first 15 degrees
When the person is asked to lower the fully abducted arm slowly and smoothly, from approximately 90 °, the limb suddenly drops to the side in an uncontrolled manner.
This is mainly due to the torn supraspinatus tendon (the tendon tears due to degenerative tendonitis because it is relatively avascular).
45
What is the significance of the subacromial bursa? Describe the condition of painful arc syndrome.
The tendon of supraspinatus is separated from the coracoacromial ligament, acromion and deltoid by the subacromial bursa.
When the bursa is inflamed (subacromial bursitis), abduction of the arm is extremely painful during the arc of 50° to 90° (“painful arc syndrome”).
The pain may radiate as far distally as the hand.
Acute pain is also felt lateral to the acromion.
46
Define dermatome
the area of skin supplied by a single spinal
nerve
(e.g., C5. If you trace all the cutaneous nerves in the C5
spinal nerve to the skin, it would be the area of the lateral arm to
just below the elbow)
47
Define myotome
the group of muscles innervated by a single nerve root
48
Define cutaneous distribution of a peripheral nerve
an area of skin this peripheral nerve innervates.
When nerve fibres leave the spinal cord, they travel through
their spinal root and then often get redistributed via the nerve
plexus (e.g., brachial or lumbosacral plexus) and become peripheral nerves.
often has nerve fibres from several spinal roots.
It is not a dermatome
(E.g. axillary nerve innervates lateral shoulder and arm; regimental badge area).
49
Cervical nerves 5, 6 and 7 emerge above the corresponding numbered
vertebra, while cervical nerve 8 emerges below vertebra C7. Explain why this is so.
There are 7 cervical vertebrae & 8 cervical nerves.
The first cervical nerve emerges from the spinal cord and passes between the base of the skull and the 1st cervical vertebra; thus the 8th nerve emerges below C7.
From T1 down, the spinal nerves exit below their corresponding vertebra.
50
Which nerve is likely to be injured in mid-shaft humeral fracture and why?
Radial nerve; the nerve runs in the radial (or spiral) groove on the posterior surface of the shaft of humerus.
It is closely associated with the bone and is likely to be injured
in mid-shaft humeral fracture.
51
What would be the effect of mid shaft humeral fracture on movement at the elbow?
No effect or weakened extension of the elbow.
Flexion is fine.
Most of the nerve supply to the triceps the three heads of the triceps branches prior to the radial nerve entering the spinal groove or just in the proximal part of the groove.
As they most likely branch before the nerve lesion there will be no or little compromise of extension.
Anconeus is paralysed but this has only a minor role in elbow extension.
52
Explain why mid shaft humeral fracture causes poor wrist and finger extension?
Injury to the radial nerve in the radial groove would result in paralysis of
brachioradialis and all extensor muscles of the wrist and fingers. results in “wrist drop” (i.e. inability to extend the wrist and fingers at the metacarpophalangeal joints (MCP joints)
wrist is flexed because of unopposed flexor muscles & gravity
53
Precisely, where in the injured arm in a mid shaft humeral fracture would the surgeon feel for arterial pulses?
In the cubital fossa (brachial pulse)
| at the wrist (radial pulse between flexor carpi radialis & brachioradialis & ulnar pulse above the flexor retinaculum)
54
If the brachial artery was injured in a mid shaft humeral fracture, describe and explain the pattern of colour change you would expect and the level of its upper limit in the arm.
Bruising of the cubital fossa & ischemia & pallor of the forearm.
The distal limb would be pale below site of the lesion.
Some colour may remain in the limb if superior ulnar
collateral arteries arise superior to vessel damage.
The deep brachial artery anastomoses with the recurrent radial artery, also providing some blood flow to forearm.
55
Concerning the elbow joint, joints of the forearm and the wrist joint:
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.
56
What is 'pulled elbow' & why does it happen more often in children?
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.
57
Why is supination a more 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).
58
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.
59
What bony structures can be palpated around the elbow?
Lateral & medial epicondyle of the humerus, olecranon process of the ulna, & head of radius
60
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.
61
Explain why it is difficult to form a fist following radial nerve lesion.
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.
62
Explain the loss of height & spinal 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.
63
What anatomical abnormalities in the spinal column occur in Spina Bifida
A common congenital anomaly of the vertebral column in which the laminae of the lower lumbar vertebrae (most commonly 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.
64
What general factors contribute to the stability & mobility of the spinal 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.
65
Which movements are possible in the cervical, thoracic & lumbar regions of the spine & 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.
66
Why are the cervical vertebrae prone to whiplash injuries?
The ligaments connecting the vertebrae are short and thin. Because of the mobility of the cervical spine, 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.
67
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)
68
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)
69
What are “intrinsic” and “extrinsic” muscles of the hand?
Intrinsic muscles: originate & insert within the hand and are responsible of movements of the thumb and fingers.
Extrinsic muscles of the hand: originate in the forearm and insert into structures in the hand to allow movements of the thumb and fingers.
70
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?
```
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.
71
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?
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.
72
Which vital function of the thumb will be affected as a result of damage to the median nerve at the wrist? Explain.
Loss of accurate opposition of the thumb to other fingers.
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
73
What common action do the lumbricals and interossei muscles perform and at what joints?
Why do you need them to be able to write properly?
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 & 1stfinger and partially extended (IP joints) of the ring finger.
74
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)
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 4thfinger (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.
75
How might a swelling proximal to the wrist joint be connected with infection in the tip of the thumb? (consider the synovial sheath)
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.
76
Can you explain why the nerve supply to the nail bed
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 development of the hand
77
What is the attachment of the flexor retinaculum
The flexor retinaculum is attached:
medially to the pisiform and the hook of the hamate bones
laterally to (the tubercle of) the scaphoid and the trapezium bones.
78
In carpal tunnel syndrome:
Why is there no tingling in the little finger?
Why would no tingling be felt in the palm of the hand?
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.
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.
79
The Iliotibial Tract (ITT)
a longitudinal thickening of the fascia lata, which is strengthened posteriorly by fibres from the gluteus maximus. It is located laterally in the thigh, extending from the iliac tubercle to the lateral tibial condyle.
three main functions:
Movement: acts as an extensor, abductor and lateral rotator of the hip, with an additional role in providing lateral stabilisation to the knee joint.
Compartmentalisation: The deepest aspect of ITT extends centrally to form the lateral intermuscular septum of the thigh and attaches to the femur.
Muscular sheath – forms a sheath for the tensor fascia lata muscle.
80
In the standing position, which are the main weight bearing bones in
the lower limb?
Femur, tibia and calcaneum
81
should an individual fall from a height and land on their feet, what
parts of the skeleton should you x-ray and why?
whole of the lower limb and the vertebral column.
The direction of the force passes up from the feet, through the lower limb to the pelvis and vertebra.
Hence any weight bearing bones and joints can be affected
82
What is the function of the femoral canal?
The canal contains no discrete structures other than a lymph nodes
The canal acts as a “dead space” to allow for the distension of the femoral vein, particularly during heavy exercise, to accommodate venous return from the limb.
83
What are the actions of the quadriceps femoris muscle
| What is the purpose of the smooth fascial covering of the rectus femoris muscle
extend the knee joint
Since the rectus femoris takes origin above the hip joint; acting on its own assists in the flexion of the hip
the smooth fascial covering of the muscle helps it to move smoothly over the adjacent muscles.
84
Explain why the vastus medialis muscle has horizontal fibres to the patella?
During movements of the knee, there is a tendency for the patella to be displaced laterally.
In order to overcome this, the horizontal fibres of vastus
medialis help to prevent this displacement.
Moreover, the lateral condyle of the femur is at a slightly higher elevation compared to the medial condyle. This also assists in patellar stability.
85
Where and how would you locate the femoral vein to obtain venous blood in a collapsed patient?
lies within the femoral triangle
medial to the femoral artery
Establish the position of the femoral artery whose pulsations can be felt 2 to 3 inches below the inguinal ligament.
The artery enters the thigh passing underneath the inguinal
ligament at the mid-inguinal point.
86
Why might a patient complain of pain and paraesthesia on the medial side of the lower leg following stripping of the long saphenous vein for varicosities?
The long saphenous vein in the leg is accompanied by a cutaneous (sensory) branch (saphenous nerve) of the femoral nerve. Stripping of the vein may lead to trauma or injury to this nerve which innervates the medial side of the lower leg.
87
explain how the femoral nerve could be damaged in a pelvic fracture
The femoral nerve arises from L2, L3 and L4 lumbar nerves in the substance of the psoas muscle and enters the thigh deep to the inguinal ligament.
The psoas muscle lies anterior to the sacro-iliac joint.
The nerve passes underneath the inguinal ligament which stretches between the pubic tubercle on the superior pubic ramus and the anterior superior iliac spine.
88
How would you test (i) the power of flexion of the hip, (ii) the power of knee extension?
i. Ask the patient to lie on their back and acutely flex the hip on the abdomen to flatten the lumbar spine.
ii. Ask the patient to sit on a chair and extend the knee against resistance.
89
Explain sensory supply to the thigh from the femoral nerve
The lateral side of the thigh is supplied by the lateral (femoral) cutaneous nerve of the thigh from the lumbar plexus
the front and intermediate aspects of the thigh are innervated by the anterior and medial cutaneous nerves which are branches of the femoral nerve
90
What other nerve, apart from femoral, supplying the thigh passes close to the sacro-iliac joint and might be injured by a pelvic fracture?
The obturator nerve.
91
Which hip movement would you examine to test the integrity of the obturator nerve?
Adduction – the adductors of the hip (adductor longus, brevis, magnus, gracilis, pectineus and obturator externus) are all supplied by the obturator nerve.
92
If the femoral nerve was divided, why would there be sensory loss in part of the foot and state where?
A sensory branch of the femoral nerve called the saphenous nerve (running alongside the great saphenous vein) innervates the medial aspect of the foot.
93
Why is hip extension limited to only about 15°?
Because of the anteriorly placed strong iliofemoral ligament which prevents hyperextension; the ligament becomes very taut in extension of the hip joint.
94
What is the structural basis for classifying the hip fracture as being
intracapsular or extracapsular?
The capsule of the hip joint attaches:
proximally to the acetabulum
distally to the neck of the femur
anteriorly to the intertrochanteric line and the root of
the greater trochanter
posteriorly to the intertrochanteric crest.
Fractures of the femoral neck that involve the bone within the margins of the capsule are classified as intracapsular
those that occur beyond the trochanters are classified as extracapsular.
95
Why should a subcapital fracture in the elderly often lead to avascular
necrosis of the femoral head while a pertrochanteric fracture usually heals well with a pin and plate procedure?
A subcapital fracture may tear and damage the joint capsule thereby
disrupting the blood supply to the femoral head; branches from the medial circumflex artery & to a lesser extent the lateral circumflex artery run in the capsule retinacula.
Disruption of blood supply to the head would ultimately result in femoral head undergoing necrosis (avascular necrosis).
Pertrochanteric fracture being outside the joint capsule, leave the retinacula undisturbed and thus does not disrupt blood supply.
96
What bony landmarks are used to measure limb length at various points?
Whole limb: ASIS to medial maleolus
Hip: ASIS to Grt Trochanter
Femur: (ASIS or) Grt Troch to knee joint line
Tibia: Knee joint line to med malleolus
97
Why, on examination of a patient with fractured neck of the femur, would you often find shortening of the limb and lateral (external) rotation of the foot?
Shortening of the limb:
This occurs because the strong muscles of the thigh (flexors, adductors and extensors) pull the distal fragment of the femur upwards; thus the leg is shortened.
Lateral (external) rotation of the foot:
Fractured neck of the femur allows the shaft of the femur to move
independently of the hip joint; axis of rotation of the femur normally passing through the head shifts to pass through the greater trochanter and along the long axis of the femoral shaft. Iliopsoas muscle which in normal situation also acts as a medial rotator, now acts as a lateral rotator of the femur because of the fractured neck.
98
Why, on examination of a patient with a dislocation of the hip, would you often find shortening of the limb and medial (internal) rotation of the foot?
Shortening of the limb:
During hip dislocation the head of the femur is pulled upwards by the strong flexor muscles (iliacus & psoas major), extensors (gluteus maximus and hamstrings) and adductors causing limb shortening. In posterior hip dislocation (which occurs in motor car accidents when the flexed knee hits against the car dashboard) the femoral head is pushed backwards over the posterior margin of the acetabulum and comes to lie on the lateral surface of the ilium.
Medial(internal) rotation of the foot:
The anterior parts of the gluteus medius and minimus pull on the greater trochanter and cause the thigh to rotate medially.
99
What bony landmarks are used to determine the course of the sciatic nerve.
Hence, which injury to the hip joint may damage the sciatic nerve?
The sciatic nerve emerges horizontal from the pelvic cavity mid way between the posterior superior iliac spine and the ischial tuberosity.
It then descends into the thigh vertically at the mid point between the ischial tuberosity and the greater trochanter.
Hence, posterior dislocation of the femoral head from the acetabulum would stretch or severely damage the sciatic nerve (e.g. consider
dashboard impact of front seat occupants in RTA).
100
What is the principal function of the gluteus maximus muscle and the iliotibial tract?
Gluteus maximus extends the thigh from the flexed position and causes lateral rotation of the thigh; also helps rising from a sitting position. It is important in running when a powerful thrust off the trailing foot is required.
Fibres from the gluteus maximus insert into the iliotibial tract (specialised condensation of the deep fascia – fascia lata – of the thigh) which crosses the knee joint to be attached to the tibia. It helps to steady the femur on the tibia during standing by supporting and keeping the knee joint in extension.
101
Explain the significance of the “safe area” for intramuscular injection into the buttock?
Intramuscular injection into the buttock is aimed at the upper outer quadrant (“safe area”) to avoid injuring the sciatic nerve and other neurovascular structures in the medial and inferior parts of the gluteal region.
Using bony landmarks, it can be found under an outstretched hand when the tip of the thumb on the ASIS and the thumb/thenar eminence are along side the iliac crest.
102
Which ligaments convert the greater and lesser sciatic notches into foramina?
What is the role of these ligaments in the erect posture?
Sacrospinous & sacrotuberous ligaments.
The ligaments limit rotation (upward movement) of the inferior part of the sacrum during transmission of weight of the body down the vertebral column in erect posture.
103
Why would damage to the superior gluteal nerve cause a positive
Trendelenberg sign?
Superior gluteal nerve supplies gluteus medius and minimus. Both these muscles are involved in stabilising the pelvis during walking.
104
Why would damage to the inferior gluteal nerve not cause a positive
Trendelenberg sign?
Inferior gluteal nerve supplies gluteus maximus which acts on the hip joint - the muscle is a powerful extensor of the hip joint during activities such as brisk walking or running.
105
Where do the gluteal nerves originate from?
The gluteal nerves (superior & inferior) originate from the lumbo-sacral plexus;
Their root values are L4 and S1.
106
What course do the gluteal nerves follow to reach the muscles they
innervate?
They leave the pelvis via the greater sciatic foramen.
Superior gluteal nerve passes superior to the piriformis muscle
inferior gluteal nerve passes inferior to the piriformis muscle
107
Between which bony points would you measure to confirm right lower limb was shorter than the left?
Distinguish between apparent and true limb shortening.
What would you measure to show shortening in the hip?
Greater trochanter of femur & the medial malleolus
true length of leg; the distance between the two points would be greater on the left side.
Apparent limb shortening is caused by e.g. fixed joint deformity or pelvic tilt.
True limb shortening involves actual loss of bone length.
Distance between the anterior superior iliac spine & greater trochanter of the femur; the distance between the two points would be greater on the unaffected side.
108
Explain the significance of the process of “locking and unlocking” of the knee
When the knee is fully extended with the leg and foot on the ground, the knee "locks” because of medial rotation of the femur on the tibia.
This movement enables the lower limb to become a solid column to support the weight of the body.
In the locked position, the thigh and leg muscles relax without making
the knee joint unstable.
In order to flex the knee, the knee has to “unlock”; this is done by contracting the popliteus muscle which results in rotating the femur laterally on the tibia so that flexion of the knee can take place.
109
State the tissue and shape of the menisci of the knee joint
| give two functions
crescent-shaped fibrocartilaginous plates that are found on
the articular surface of the tibia.
help in deepening the articular surface
also act as shock absorbers.
110
Which knee menisci is the most common to be torn and why?
The medial meniscus is the most commonly torn of the two menisci of the knee joint.
because it is firmly adherent to the tibial (or medial) collateral ligament. Although the tibial collateral ligament is broad, it is weaker
than the fibular (or lateral) collateral ligament which is a strong round band of tissue.
Excessive or violent trauma on the lateral aspect of the knee (e.g. A kick) may result in excessive medial displacement of the tibia causing the tibial collateral ligament to tear/rupture and a concomitant tearing of the medial meniscus.
111
Why might a “locked” knee be the presenting sign of a torn meniscus?
A torn meniscus may result in it becoming dislodged (or its fragment breaking away) and becoming trapped within the knee joint cavity causing the knee to become “locked”.
112
What are “housemaid’s knee” and “clergyman’s knee”?
"Housemaid’s knee”: inflammation of the prepatellar bursa; the bursa
becomes distended with fluid and forms a swelling anterior to the knee.
Prepatellar bursitis usually results from friction caused by excessive rubbing of the skin against the patella.
“Clergyman’s knee": inflammation of the subcutaneous infrapatellar
bursa; the bursa becomes distended with fluid as a result of excessive friction between the skin and tibial tuberosity. The oedema occurs over the proximal end of tibia.
113
What are the ‘Drawer’ tests and what do they show?
performed by pulling the leg forward or backward with the knee in
flexed position (90°).
The examiner should sit close to the foot to steady it. The leg is grasped below the knee with both hands and the tibia pulled forward.
Abnormal mobility suggests rupture of the anterior cruciate ligament. backward displacement of the tibia with abnormal mobility would suggest posterior cruciate ligament rupture.
114
Explain the structural and functional basis of a pulled hamstring
common in persons who undertake activities that require violent
or sudden muscular exertion.
tearing (part/complete) of tendinous attachments of the
hamstrings to the ischial tuberosity resulting in the rupture of blood vessels supplying the muscles.
115
Why is a popliteal pulse difficult to feel even in the normal individual?
The popliteal artery lies quite deep in the popliteal fossa; the artery lies deep to the popliteal vein and the tibial nerve.
With the knee is full extension, the skin and the underlying fascia become taut and make it difficult to feel the pulsations of the popliteal artery.
In order to feel the pulse, the knee has to be in flexion and the fingers pressed firmly into the popliteal fossa to press the artery against the posterior aspect of the femoral intercondylar area to feel the pulse.
116
List four structures that you think may be the cause of a swelling in the region of the popliteal fossa?
aneurysm (will be pulsatile swelling)
popliteal (Baker’s) cyst (formed as a result of herniation of the synovial membrane of the knee joint)
abscess
tumour
enlarged lymph nodes
117
Which muscles are involved in dorsiflexion and in plantarflexion at the ankle joint?
Dorsiflexion – Tibialis anterior, extensor hallucis longus, extensor digitorum longus & peroneus (fibularis) tertius
Plantarflexion – Gastrocnemius, soleus, plantaris, flexor hallucis longus, flexor digitorum longus & tibialis posterior
118
Name the major ligaments at the ankle joint and explain which ligament is most frequently affected in inversion injuries at the ankle.
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Lateral ligament (made up of anterior & posterior talofibular ligament & calcaneofibular ligament)
commonly injured in inversion injuries (ankle sprain)
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Medial ligament (deltoid ligament)
(Made up of the tibionavicular, anterior & posterior tibiotalal, and tibiocalcaneal ligaments)
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119
In severe sprain of the ankle, why is it not uncommon to find that the patient has an avulsion of the fifth metatarsal tuberosity?
Peroneus (fibularis) brevis tendon is attached to the tuberosity of the 5th metatarsal.
120
At which joint(s) does inversion & eversion of the for occur?
subtalar joint & calcaneocuboid joint.
121
What is the functional significance of the capacity of the foot to be able to undertake the movements of inversion and eversion?
The movements allows one (a biped) to walk on uneven surfaces.
122
Which muscles help to hold up the medial & lateral arches of the foot?
Medial longitudinal arch : Tibialis anterior & posterior (attaching to the 1stmedial cuneiform), peroneus (fibularis) longus & flexor hallucis longus.
Lateral longitudinal arch : The calcaneus, cuboid & lateral two metatarsals form the lateral arch mainly; the peroneus (fibularis) brevis may help in holding up the lateral longitudinal arch
123
What causes 'flat foot' (pes planus) & how does it occur?
due to “fallen arches”, usually the medial parts of the longitudinal arches.
During standing, the plantar ligaments and plantar aponeurosis stretch under body weight; if these ligaments become abnormally stretched, the calcaneonavicular ligament can no longer support the head of the talus. The talus displaces inferomedially, causing flattening of the medial longitudinal arch.
124
Why does the foot arch in a child appear to be flat?
The arches have not developed fully and also due to the presence of subcutaneous adipose tissue in the sole of the foot.
125
Although in his mid-70s, a man enjoyed doing the gardens of his ‘elderly’ neighbours, but he’d found it difficult this winter.
“ After 10 minutes of digging I get cramp in my left calf, doctor. It goes off when I stop, but comes on very quickly again when I start digging again.”
“ Do you get it when you’re walking on the flat?” asked the doctor.
“ Not really, I can go half a mile easily, if I take it steady.”
“ Have you had any cramps in the other leg and do you get any pain in the chest when you’re gardening?” asked the doctor.
“ No doctor, I’m as fit as a fiddle except for this.”
“ No dizzy do’s or black outs? You’ve never smoked have you?” asked the doctor.
“ Not since I was about 8 doctor! And I’ve never had a dizzy do in my life.”
What is the underlying problem and what is this pattern of symptoms called?
At which 2 sites in the arterial system could this man's problem be located?
What other tissues in his limb could be affected & how would this manifest?
Which arterial pulses would the doctor need to record?
Which 2 metabolic abnormalities could be important in this case?
Arterial disease; Chronic arterial insufficiency (ischaemia).
Intermittent claudication
Heart (recent MI, atrial fibrillation or mitral valve stenosis) or diseased aorta.
Nerves - neuropraxia
Skin – ulcerations
Femoral & popliteal pulse
Diabetes
Hypercholesterolaemia
126
What is the difference between a simple and compound fracture, and explain why which of these fractures poses a greater risk of infection?
In simple fracture, the overlying skin is healthy and closed. In compound
fracture, the overlying skin is breached and the fracture site is itself exposed
to the outside environment. The compound fracture poses a greater risk of
infection.
127
When can a fracture be described as being pathological?
A pathological fracture is one in which the fracture occurs through a bone
already weakened by underlying disease (e.g. brittle bone disease,
osteocarcinoma, osteoporotic bone, cysts, etc.)
128
What causes a stress fracture?
In these fractures (also termed as ‘fatigue fractures’) the bone is fatigued by
repetitive stress; common example is a fracture of the second metatarsal in
young adults who walk long distances, tibial fractures in long distance runners
& hurdlers.
129
In bone fractures, explain what is callus and what is its function?
The fibroblasts in the granulation tissue (haematoma at the site of the
fracture) undergo metaplasia and change into chondroblasts. The
chondroblastic tissue forms islets of cartilage around collagen fibres; this
mass of tissue is called ‘callus’ which temporarily helps to bind the two bone
ends together.
130
Describe the actions of the muscles in the anterior & lateral compartment of the leg
Tibialis anterior, extensor hallucis longus, extensor digitorum longus &
peroneus (fibularis) tertius all dorsiflex the ankle. Tibialis anterior also inverts
the foot at the subtalar joint. Peroneus (fibularis) tertius everts the foot at the
subtalar joint. Extensor hallucis longus extends the great toe and extensor
digitorum longus extends the lateral four digits.
131
In general, what is the function of the retinacula in the ankle?
The extensor retinacula bind down the tendons of the muscles in the antero-
lateral compartments and prevent them from bowstringing during movements
at the ankle.
132
With reference to local anatomy, where in the foot would you be able to palpate the dorsalis pedis artery?
The dorsalis pedis artery is the continuation of the anterior tibial artery (a
branch of the popliteal artery ) into the dorsum of the foot. Its pulsation can
be felt between the tendons of extensor hallucis longus and the medial most
tendon (going to the 2
nd
digit) of the extensor digitorum longus muscle.
133
A traumatic injury to the leg may lead to a condition called “compartment
syndrome”. How does this syndrome occur and what are the short and long-
term consequences of such a disorder?
The limbs are organised into compartments which are bounded by bone and
deep fascia and contain muscles with their nerve and blood supply together
with nerves and vessels to more distal parts of the limb. Muscle within the
fascial compartment is perfused by blood. Trauma to the fascial compartment
may rupture the blood vessels and cause a temporary rise in compartmental
tissue pressure. If a sustained rise in tissue pressure is above the arterial
perfusion pressure, muscle and nerves will be deprived of blood supply.
Ischemic muscle releases factors which increase capillary permeability and
worsen the situation.
Nerve fibres are susceptible to ischemia; the thin cutaneous nerve fibres are
affected more than the motor fibres, which causes distal paraesthesia before
motor function.
134
Where in the ankle would you find the great (long) & the lesser (short) saphenous veins?
The great (long) saphenous vein runs above (anterior to) the medial malleolus
while the lesser (short) saphenous vein runs behind (posterior to) the lateral
malleolus. Unlike other superficial veins in the body, the great saphenous
vein is considered to be one of the superficial veins that is relatively constant
in location.
135
After a “cut down procedure” for insertion of an intravenous line into the great
(long) saphenous vein, patient complained of numbness and loss of sensation of the medial aspect of the foot.
What is the explanation for this presentation?
The saphenous nerve, which is a sensory branch of the femoral nerve, runs in
close proximity to the long saphenous vein in the leg. Insertion of an
intravenous line into the vein and in the attempt to secure the line with a
ligature may compress the nerve leading to disturbances in sensory supply to
relevant region.
136
Give two reasons why a 'kick in the shin' may hurt so much?
The surface of the tibia along most of the medial aspect of the leg has only
subcutaneous soft tissue. The bone is covered by periosteum which has a
rich nerve supply.
137
What are some possible risk factors for intermittent claudication?
History of arterial disease (coronary by-pass)
Risk factors for arterial disease.: smoking
diabetes
possible high fat/high salt diet (pre-prepared
meals)
age
138
List the pulses in the lower limb & state in anatomical terms where they are palpable
Femoral artery: Mid-inguinal point.
Popliteal artery: Popliteal fossa.
Posterior tibial artery: Behind medial malleolus
Dorsalis pedis artery: Dorsum of the foot between tendons of extensor
hallucis longus and extensor digitorum
139
If The femoral and popliteal arterial pulses are normal on each side, and On the right side, the posterior tibial arterial pulse is normal whereas the dorsalis pedis pulse is diminished; what do you conclude from this?
Occlusion has most likely occurred in the anterior tibial artery; posterior tibial
artery is patent.
140
Whilst waiting for an angioplasty, a patient develops an acute arterial
occlusion due to blood clots in his right popliteal artery. What signs and symptoms will be present in his leg?
The 6 "P's": pain, paraesthesia, pallor, perishingly cold,' pulselessness', paralysis (weakness)
141
Young people transmit transient forces as high as 2000 kg/cm sq. through their
Achilles tendons, yet rupture of the tendon tends to only occur after middle age.
Hence, what pathological changes occur in tendons during ageing?
The injury may be due to age-related degeneration of the tendon or poorly
conditioned middle-aged persons with a history of calcaneal tendonitis. It is known
that the lower part of the tendon has a poor blood supply is often a point of
weakness.
142
A 17 year-old was having her plaster changed two weeks after
transposition of her left tibial tubercle for recurrent patella dislocation. With her plaster off,
she realised she could not move her foot properly and the orthopaedic SHO was asking
her about it.
“Well, my foot is pointing downwards and I can’t lift it up, except with my hand.”
“Have you had a lot of pain since your operation?” asked the SHO.
“Only for the first few days then I had some tingling between my toes, but it went away
after a few more days.”
On examination, the SHO found normal power and sensation in her right leg. On the left
side, he operation site was not tender and looked fine. Her foot was planter flexed. With
her foot in the neutral position, the woman had normal plantar flexion power when she
pushed against the SHO’s hand. Pushing upwards against his hand, she could manage
no more than a flicker of dorsiflexion. She could extend all her toes but the SHO could
easily push them into flexion again. Similarly, she could evert her foot quite well, but he
could easily overcome it with his hand around her foot. Pinprick testing showed she had
impaired sensation along the lateral side of the leg extending on to the dorsum of the foot.
The area of the skin over the lateral side of the big toe and the medial side of the adjoining
toe and the inter-digital cleft felt numb.
Which muscle groups are weak in this lady’s left leg?
Which nerve(s) supply the area of impaired sensation & numbness?
What nerve has been damaged? What has caused it? What is the name of this particular disability?
Explain why she had tingling for a few days, which then stopped?
What will be the ultimate outcome in terms of sensation & motor function?
Dorsiflexors (or extensors) – tibialis anterior, extensor hallucis longus & extensor
digitorum longus - & everters (peroneus longus & brevis) of the foot.
Deep fibular (peroneal) nerve; this area may also receive sensory nerve fibres from the superficial fibular (peroneal) nerve.
```
Common fibular (peroneal) nerve has been damaged due to pressure from the
plaster cast causing foot drop.
```
Compression or pressure on the nerve results in paraesthesia (numbness and
tingling); compression affects nerve conduction and its effects are time-dependent.
With prolonged compression, may lead to local conduction block lasting longer; the
nerve myelin sheath will be damaged but axonal continuity is preserved.
Since axonal continuity is preserved, removal of the compression forces leads to
nerve recovery within a few weeks (usually 10 –12 weeks).
143
What is a common cause of foot drop?
Bumper injuries
144
Explain why after a peripheral nerve lesion, the area of skin which loses its
innervation may become red then dry and scaly?
A peripheral nerve contains afferent (sensory), motor (efferent) and often
autonomic fibres. Loss of sympathetic nerves to bloody vessels will remove
peripheral vasoconstrictor fibres (1). Hence, loss of the latter will lead to initially,
vasodilation (reddening). Heat loss and loss of innervation to sweat glands, will
produce dry, scaly skin.
145
List the common sites of the 'perferators' in the leg
Around the ankle
On the medial side of the calf
Around the popliteal fossa
146
Explain why people who suffer from varicose veins in the lower leg suffer from skin ulcers in the leg?
Stagnation of blood in the skin of the lower limb results in the skin being poorly
nourished. As a consequence, it breaks down into a varicose ulcer if subjected to
even minor trauma. Skin ulcers are common over the subcutaneous antero-medial surface of the tibia where cutaneous blood supply is relatively poor.
147
Explain the occurrence of oedema around the ankle in persons with varicose veins with reference to Starlings-Landis capillary forces.
Disturbances in the venous drainage of the lower limb (e.g. in cases of varicose veins) results in the build up of tissue fluid. Hydrostatic pressure increases in the veins distal to the varicosity, which increases hydrostatic pressure at the venous end of the capillaries feeding into these veins. This pressure rise means there is less tissue fluid (interstitial fluid) resorption back into the capillaries. Accumulation
of this tissue fluid is seen as oedema in the patient.
148
Why might stripping the short saphenous vein for varicose veins leave the patient with a tingling in his little toe?
The sural nerve (formed by the union of the medial sural cutaneous branch of the
tibial nerve and the fibular communicating branch of the common fibular nerve)
running alongside the short saphenous vein supplies the skin on the posterior and
lateral aspects of the leg and on the lateral side of the foot.
149
Where would you hope to find the great (long) saphenous vein in a patient who
requires an intravenous line inserted urgently because all the other veins have
collapsed?
The great (long) saphenous vein runs in front of the medial malleolus – the anatomical positioning of this vein in the body is relatively constant. Another site of location of the vein is one hand’s breadth posterior to the patella.
150
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What is the possible cause of venous stasis and blood clotting in the so-called
“economy class syndrome”?
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Venous stasis (stagnation) which is an important cause of thrombus formation
(thrombosis – blood clotting) is aggravated by muscular inactivity.
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