Ms 1-3: Osteology Of The Upper Limb

Front 1

Describe the mechanical and physiological functions of bones and the skeleton

Back 1

- Mechanical
1. Support
2. Protection
3. Movement
= joints, motor power, neurological control
- Physiological
4. Haematopoiesis
= long bones, pelvis and ribs
5. Mineral homeostasis
= Calcium and phosphate

Front 2

What are the 2 major types of bone?

Back 2

1. Cortical = dense bone built for strength. Arranged in Haversian systems
2. Cancellous bone = spongy, trabeculated bone, light weight

Front 3

Describe the classification of bone by shape and their significance

Back 3

Bones may be:
- Long
- Short
- Flat
- Irregular
- Sesamoid
- Accessory and heterotrophic bones

- Shape is significant as shows bones role e.g. clavicle is long and curved to act as a bone strut, connecting the axial and appendicular skeletons. Also signifies the forces running along that bone

Front 4

Describe the structural and functional classification of joints

Back 4

1. Fibrous joints = surfaces jointed together by fibrous tissue
- Sutures = occur only in the skull where adjacent bones are linked by a thin layer of connective tissue termed a sutural ligament
- Gomphosis = occur only between the teeth and adjacent bone-in these joints, short collagen tissue fibers in the periodontal ligament run between the root of the tooth and the bony socket
- Syndesmosis = joints in which two adjacent bones are linked by a ligament, for example, the ligamentum flavum, which connects adjacent vertebral laminae, or by an interosseous membrane, which links, for example, the radius and ulna in the forearm

2. Cartilagenous joints
- Synchondrosis (primary cartilagenous) = where two ossification centers in a developing bone remain separated by a layer of cartilage, for example the growth plate that occurs between the head and shaft of developing long bones, or costal cartilages connecting to the sternum
- Symphysis (secondary cartilagenous) = where two separate bones are interconnected by cartilage-most of these types of joints occur in the midline and include the pubic symphysis between the two pelvic bones, and intervertebral discs between adjacent vertebrae

3. Synovial joints = elements involved connected by a narrow articular cavity
- The joint is surrounded by a joint capsule = dense connective tissue
- Lined by synovial membrane
- Producing synovial fluid for nutrition and reduction in friction
- The joint has a joint cavity
- The articular surfaces are covered in hyaline cartilage

Front 5

Describe the 2 layers of the synovial membrane

Back 5

1. Intima (closest to joint cavity) = cells phagocytic or secretory → secretes proteoglycans and enzymes
2. Sub-intima = highly vascular loose connective tissue. Produces synovial fluid from filtered plasma seeped from the blood vessels

Front 6

Describe the classification of synovial joints

Back 6

Classified by shapes and movements:
- Plane = permits gliding movements e.g. acromioclavicular joint
- Pivot = permits rotation e.g. atlanto-axial joint
- Hinge - permits flexion and extension e.g. humero-ular joint
- Condyloid - permits 360 degree movement in a single plane (biaxial) e.g. metacarpophalangeal joint
- Saddle = can move up and down with limited movement e.g. trapezo-metacarpal joint
- Ball and Socket - permits a full range of movement in all planes e.g. hip joint

Front 7

What is the origin and insertion of a muscle?

Back 7

- Origin = End of a muscle usually remaining fixed during contraction (usually proximal attachment)
- Insertion = end of a muscle usually moving during contraction (usually distal)

Front 8

Define agonist and antagonist

Back 8

- Agonists = prime mover i.e. the main muscle causing a movement
- Antagonists are muscles producing the opposite movement to the agonist

Front 9

What is a synergist?

Back 9

Assists prime mover in achieving the specific movement in a situation where prime mover is capable of activating more than one movement.

Front 10

What is a fixator?

Back 10

Steady proximal parts of a limb while movements occur in distal parts

Front 11

Describe 7 ways of naming muscles

Back 11

1. Location e.g. tibialis anterior
2. Size e.g. gluteus maximus
3. Number of origins e.g. biceps brachii
4. Shape e.g. serratus anterior
5. Origin and insertion e.g. sternomastoid
6. Action e.g. adductor longus
7. Direction of fibres e.g. transversus abdominis

Front 12

What are the roles of the clavicle?

Back 12

1. Strut = allows movement
2. Attachments for muscles
3. Transmits force from the upper limb
- The only horizontal bone in the body
- Subcutaneous in whole length

Front 13

Where are fractures most likely on the clavicle?

Back 13

- Most commonly fractured long bone
- Fractures usually along weak point = between lateral and middle thirds

Front 14

Label this diagram and side the clavicle

Back 14

1. Lateral end = articulation with acromion
2. Conoid tubercle
3. Shaft of clavicle
4. Muscle attachment of subclavius
5. Medial end = articulation with sternum

- Left clavicle

Front 15

Label this diagram

Back 15

1. Acromial angle
2. Acromion
3. Coracoid process
4. Inferior angle
5. Infraspinous fossa
6. Lateral border
7. Glenoid fossa
8. Medial/vertebral boder
9. Neck of scapula
10. Spine of scapula
12. Superior angle
13. Superior border
14. Suprascapular notch
15. Supraspinous fossa

Front 16

Label this diagram

Back 16

2. Acromion
3. Coracoid process
4. Inferior angle
6. Lateral border
7. Glenoid fossa
8. Medial border
9. Neck of scapula
11. Subscapular fossa
12. Superior angle
13. Superior border
14. Suprascapular notch

Front 17

Label this diagram

Back 17

1. Acromion
2. Coracoid process
3. Glenoid fossa
4. Inferior angle
5. Infraglenoid tubercle
6. Infraspinous fossa
7. Subscapular fossa
8. Spine of scapula
9. Supraglenoid tubercle
10. Greater scapular notch

Front 18

Label this diagram

Back 18

1. Anatomical neck
3. Greater tuberosity
5. Head
6. Bicipital / intertubercular groove
7. Lateral lip of bicipital groove/Deltoid tuberosity
8. Lesser tuberosity
9. Medial lip of bicipital groove
10. Surgical neck

Front 19

Label this diagram and note the position of the radial groove

Back 19

1. Antero-medial surface
2. Capitulum
3. Coronoid fossa
5. Lateral epicondyle
6. Lateral epicondylar ridge
7. Medial epicondyle
8. Medial epicondylar ridge
10. Olecranon fossa
11. Posterior surface
12. Radial fossa
13. Trochlea

Front 20

Label this diagram

Back 20

1. anterior border
2. oblique line
3. anterior surface
4. head
5. interosseous border
6. lateral surface
7. neck
8. posterior border
9. posterior surface
11. radial tuberosity

Front 21

Label this diagram

Back 21

1. anterior border
9. interosseous border
12. styloid process
13. ulna notch

Front 22

Label this diagram

Back 22

1.anterior border
2.anterior surface
3.coronoid process
4.interosseous border
5.medial surface
6.olecranon
7.posterior border
8.posterior surface
10.supinator crest
11.trochlear notch
12. tuberosity of ulna

Front 23

Label this diagram

Back 23

1. anterior surface
2. groove for muscle (ECU)
3. head *Note this is distal NOT proximal*
4. interosseous border
6. posterior surface
7. styloid process

Front 24

Label this diagram

Back 24

1. ulna
2. radius
3. styloid process ulna
4. styloid process radius
5. pisiform
6. triquetrum
7. lunate
8. scaphoid
9. scaphoid tubercle
10. hamate
11. hook of hamate
12. capitate
13. trapezoid
14. trapezium
16. metacarpals
17. phalanges

Front 25

Describe the prevalence of limb abnormalities

Back 25

- 2/1000 live births
- May have genetics or non-genetic causes e.g. thalodmide
- Occur eary = 24-36 days → before a woman necessarily knows she's pregnant

Front 26

What are limb buds?

Back 26

- Form opposite the spinal cord segment that will later innervate them = Upper limbs are C5-T1 and lower limbs are L2-S2
- Outer covering of ectoderm over a core mass of mesenchyme
- Upper limb bud develops 1-2 days ahead of the lower limb bud

Front 27

What is the apical ectodermal ridge?

Back 27

- A thickening of ectoderm at the tip of each of the buds
- Synthesises growth factors
- Molecules gradually diffuse from the ridge proximally so that there is a gradient of concentration of growth factors from distal to proximal
- This triggers differentiation from distal to proximal, so that the hand cartilagenous template forms before the humerus
- Thalisomide damges the apical ridge so that there is failed limb development at the point that this occurs

Front 28

Describe 2 abnormalities in limb development

Back 28

1. Amelia = complete absence of whole limb
2. Meromelia = partial absence of limb e.g. hand attached directed onto trunk

Front 29

Describe the formation of the digits

Back 29

1. Flattening of limb buds to form paddle-shaped limbs
2. Formation of 5 thickened and distinct digital rays by rearrangement of cells and selective cell death in the mesoderm
3. Elongation and separation of digits = digits thicken and elongate, and ectodermal cells between them undergo apoptosis, so that almost all disappears except for a small amount at the base of the digit → recognisable hand by 8 weeks
4. Formation of nails = nails form from 8 weeks. Initially forms on the tips of the fingers but migrate backwards onto the dorsal surface → hence why, despite being dorsal they share the palmar nerve supply (nedian and ulnar nerve)

Front 30

Describe 2 congenital abnormalities of the digits

Back 30

1. Polydactyly = too many digital rays form (usually an extra little finger or toe)
2. Syndactyly = fused digits. Of varying severity depending on whether there is incomplete separation of digital rays → complete bony fusion, or incomplete loss of the ectoderm → thin web of skin between the fingers

Front 31

What is pre-axial and post-axial?

Back 31

- The pre-axial border of each limb is cranial and includes the thumb, big toe, radius and tibia
- The post-axial border is caudal and includes the little finger and toe, ulna and fibula

Front 32

Describe the rotation of the limbs

Back 32

- Myoblasts aggregate in each limb bud to form a large muscle mass which separates into dorsal (extensor) and ventral (flexor) components
- To get to anatomical position, the upper limb rotates laterally through 90 degrees on its longitudinal axis. This means that the elbows point posteriorly, the extensors are found posteriorly and the flexors anteriorly
- To get to anatomical position the lower limb must rotate medially 90 degrees, so that the knee faces anteriorly, the extensors lie anteriorly, and the flexors lie posteriorly

Front 33

Describe the development of innervation of the muscles and skin of the limbs

Back 33

Skin
- A regular sequence of nerve roots grow out from the developing spinal cord
- They supply skin in a regular pattern of strips called dermatomes
- Later development distorts this pattern but dermatoms can still be recognised e.g. C5 supplies skin on the preaxial border

Muscles
- Muscles are innervated in functional groups are nerves grow into the limb and find their muscles
- This creates limb plexuses e.g. the brachial plexus
- The nerves from the upper limb come from C5 to T1 of the spinal cord, so that the roots of the brachial plexus are C5 to T1
- This regular sequence becomes the brachial plexus:
1. C5 and C6 join to make the upper trunk on the preaxial border
2. C7 remains alone on axis as the middle trunk
3. C8 and T1 join to make the lower trunk on the post-axial border
- The muscles are then supplied in anterior and posterior compartments so that each trunk splits into anterior and posterior divisions
- These divisions regroup around the axillary artery
- All posterior post-axial divisions regroup into the posterior cord
- All anterior pre-axial divisions regroup into the medial and lateral cords and