LOCO EOYS 4

Question 1

which rotator cuffs cause external rotation of shoulder? [2]

Answer 1

teres minor
infraspinatous

Question 2

what are the two methods of bone formation? [2]

Answer 2

endochrondral ossification: cartilage model as precursor

intramembranous ossification: no cartilage model

Question 3

what are the characteristics of power grip?
and subtypes? [3]

Answer 3

• *power grip**
• all fingers flexed around object, thumb curled around to press agaisnt / meet fingers
• all muscles closing hand are active
• wrist extensors are active - stable base
• most primitive (new borns can do)

i) hook or snap
ii) cylindrical grasp
iii) spherical grasp

Question 4

what are deep layer muscles of the forarm? [3] where run to ? what movements?

Answer 4

flexor digitorum profundus:

• makes way to fingers and distal phalanx !
• causes flexion of the wrist, MCP, PIP and DIP joints

flexor pollicis longus

• *- forearm to distal phalanx of thumb**
• thumb flexion

pronator quadratus

• between ulnar and radius
• initiates pronation of the forearm

Question 5

ulnar nerve lesion would effect which of the following?

• flexor pollicis brevis
• oppenens pollicis
• adductor pollicis
• abductor pollicis brevis

Answer 5

ulnar nerve lesion would effect which of the following?

• flexor pollicis brevis
• oppenens pollicis
• *​- adductor pollicis**
• abductor pollicis brevis

Question 6

Answer 6

Question 7

osteoclasts

location? [1]

characteristics? [1]

derived from? [1]

function? [1]

Answer 7

osteoclasts

characteristics?
large and multinucleated

location
at sites where bone is removed

derived from? [1]
from the fusion of the granulocytes / macrophage progenitor cells

function [1]
responsible for bone resorption in response to long term calcium requirements and changing mechanical stresses.

Question 8

which muscles does the synovial sheath reduce friction of? [2]

Answer 8

flexor digitorum superficialis & flexor digitorum profundus to reduce friction of those tendons rubbing together.

Question 9

what are canaliculi?

Answer 9

Tiny canals in bone to allow for the passage of blood vessels for nutrient supply.

They appear as fine lines

Extend from capillaries to osteocytes and their matrix.

Osteocytes are interconnected by the canaliculi through processes. Communication through gap junctions.

Question 10

Answer 10

Question 11

pronation of the forearm is undertaken by pronator quadratus (deep layer) and pronator teres muscle (superficial layer).

which of these is the main muscle involved in pronation and which assists pronation?

Answer 11

pronator quadratus (deep layer): main

pronator teres muscle (superficial layer): assists

Question 12

when are bones not covered in periosteum?

Osteoprogenitor cells are located where?

Answer 12

where they articulate with other bones

Osteoprogenitor cells are located on the outside of trabecula eg beside adipocytes in periosteum

Question 13

all of the muscles of the thenar eminance are innervated by the median nerve apart from which muscle? [1]

Answer 13

all of the muscles of the thenar eminance are innervated by the median nerve apart from which muscle? [1]
adductor pollicis

Question 14

what do patients with radial nerve palsy struggle to be able to do?

why?

Answer 14

what do patients with radial nerve palsy struggle to be able to do?
- power grip

​why?
- wrist extensors are active when performing a power grip - causes stabilisation

Question 15

Answer 15

Question 16

which bones does the radiocarpal joint connect? [3]

what type of joint is it? [1]

Answer 16

which bones does the radiocarpal joint connect? [3]
- scaphoid & lunate to radius (not the ulna!)

what type of joint is it? [1]
- condyloid joint (extension and flexion and ulnar and radial devaitation (side to side)

Question 17

what are the two main types of grip? [2]
which is more complex to perfom?

Answer 17

• power grip
• precision grip - more complex

Question 18

where do you test for sensory innervation for

a) radial nerve
b) median nerve
c) ulnar nerve

Answer 18

where do you test for sensory innervation for

a) radial nerve: between thumb & first thing dorsally
b) median nerve: outside of second finger
c) ulnar nerve: outside of little finger

Question 19

why is the scaphoid a clinically significant bone? [2]

Answer 19

has a retrograde artery (comes in proximally and comes out distally)
if you get a fracture -> portion becomes avascular and necrotic

Question 20

which is the muscle of intermediate layer of forearm?

where does it run to from the medial epidcondyle?

what movements does it cause? [3]

Answer 20

which is the muscle of intermediate layer of forearm?
- flexor digitorum superficialis

where does it run to from the medial epidcondyle?
- middle phalanx

what movements does it cause?

• *- flexes the wrtist
• flexes the MCP
• flexes the PIP**

Question 21

ID B, C, E & F?

Answer 21

B: corocoid process
C: glenoid fossa
E: acromion
F: biciptial groove (inbetween the tubercles) for long head of bicep tendon

Question 22

Answer 22

Question 23

which joint permits thumb oppositon in the hand? [1]

Answer 23

carpo-metacarpal

Question 24

what is periosteum?
what is inside it?

Answer 24

Fibrous capsule surrounding bone

Carries blood and neural supply

Periosteal blood vessels penetrate the bone from this layer.

Inner periosteum is liner by osteoprogenitor cells.

These may differentiate into osteoblasts and so are important in bone growth, modelling and repair.

Question 25

Answer 25

Question 26

what is the carpal tunnel? what is the layer at the top called? which nerve runs through?

Answer 26

- At the base of the palm of the hand, there is a groove/tunnel through which **9 flexor tendons pass.** - Across the top is the **flexor retinaculum** (thickening of the deep fascia) - **median nerve runs** through the carpal tunnel

Question 27

what are deep layer muscles of the forarm? [3] where run to ? what movements?

Answer 27

_flexor digitorum profundus:_ - makes way to fingers and distal phalanx ! - causes flexion of the **wrist, MCP, PIP and DIP joints** _flexor pollicis longus_ * *- forearm to distal phalanx of thumb** - thumb flexion _pronator quadratus_ - between ulnar and radius - initiates pronation of the forearm

Question 28

muscles of the superficial layer of forearm: names? [4] where do they run from / to?

Answer 28

muscles of the superficial layer of forearm: 1. **Pronator teres** (pronates the arm) 2. **Flexor carpi radialis** (flexes the wrist) 3. **Palmaris longus (small muscle)** 4. **Flexor carpi ulnaris** (flexes the wrist) **(Pass Fail Pass Fail)** muscles of the superficial layer do not extend into the digits so they act to - **flex the wrist - pronate the arm**

Question 29

what are osteoclasts activated by? how does it cause bone remodelling? which other cells can activate them?

Answer 29

**osteoclasts** express a receptor molecule called **RANK** (receptor activator of nuclear factor). interaction with **RANKL ligand molecule expressed on osteoblasts** dissolves bone matrix: **pumps protons out to acidify & enzymes = bone remodelling** also activated by **t-lymphocytes** (can express RANKL) during **inflammation**

Question 30

what is the main mineral in the mineralised ECM in bones? [1] what other subtstance is mostly found in the bone matrix [1]?

Answer 30

what is the main mineral in the mineralised ECM in bones? [1] **calcium phosphate** what other subtstance is mostly found in the bone matrix [1]? **type 1 collagen - 90% of bone**

Question 31

how do paedatric and adult x-rays differ in appearance?

Answer 31

in children, bones are growing via **epiphyseal growth plate: lengthens the bone but is made by hyaline cartilage: _l_**_ooks seperated from the main shaft of the bon_e (cane make it look fractured)

Question 32

where do you find osteocytes? [1] characteristic feature of osteocytes [1] role of osteocytes? [1] how do u prepare bone to see ^? [1] 2

Answer 32

where do you find osteocytes? [1] - osteocytes encolosed in bone matrix, trapped in lacunae characteristic feature of osteocytes [1] - osteocyte processes role of osteocytes? [1] - respond to redeuced mechanical stress by secreting MMPs: osteocytic remodelling how do u prepare bone to see osteocyte processes? [1] - visible on ground sections (no stain, just dried) - not visible with H&E (see photo)

Question 33

which bone is this? why is this bone clinically significant? [1]

Answer 33

scaphoid _why is this bone clinically significant_ - has a **retrograde blood supply** (comes in at distal end and moves proximally) - means if fracture at proximal end -\> can become avascular -\> lead to necrosis

Question 34

bone classification: - outside, dense part of bone is called? - inside, less dense is called?

Answer 34

bone classification: - outside, dense part of bone is called: **compact** - inside, less dense is called: **spongy (trabeculae)**

Question 35

what should you consider when looking for abnormal x-rays? [5]

Answer 35

In an abnormal x ray you are looking for changes in: Shape, size and or orientation of the bones and joint surfaces Breaks in the bone Extra bone (calcification) Loss of bone Foreign objects

Question 36

what are the characteristics of power grip? and subtypes? [3]

Answer 36

* *power grip** - _all fingers flexed_ around object, thumb curled around to press agaisnt / meet fingers - all muscles closing hand are active - _wrist extensors_ are active - stable base - most primitive (new borns can do) i) **hook or snap** ii) **cylindrical grasp** iii) **spherical grasp**

Question 37

what are 4 muscles of thenar emincence? & innervation?

Answer 37

- flexor pollicis brevis - **median nerve** - oppenens pollicis - **median nerve** - abductor pollicis brevis - **median nerve** - adductor pollicis - **ulnar nerve**

Question 38

what are the movements initated by: a) lumbricals? b) dorsal interrossei? c) palmar interrossi?

Answer 38

lumbricals: **flex MCP** dorsal interrossei: **abduct fingers (DAB)** palmar interrossei **adduct the fingers (PAD)**

Question 39

what are the borders of the anatomical snuffbox? [3]

Answer 39

Question 40

which direction is extension and flexion of the thumb? which direction is adductio and abduction of thumb? what is oppositon of the thumb?

Answer 40

Question 41

which is the only rotator cuff muscle to cause internal rotation? [1]

Answer 41

**subscapularis**