MSK Axilla and Pectoral region (Weeks 1-2)

Question 1

What is the axial skeleton comprised of?

Answer 1

Skull, vertebral column, sternum, ribs

Question 2

what is the appendicular skeleton comprised of?

Answer 2

Limbs, pectoral and pelvic girdle

Question 3

What is the role of bones in the body?

Answer 3

mechanical functions, support, anchoring points for muscles, acting as levers at joints

Question 4

How are joints classified?

Answer 4

Due to the tissue which lies between the joint. You can get: fibrous, cartilaginous and synovial

Question 5

what influences stability of joints?

Answer 5

shape, sixe, arrangement of articular surfaces
ligaments
tone of muscle around joint

Question 6

Why are tuberosities, ridges and tubercles present on bones?

Answer 6

Ligament, muscle and tendon attachment

Question 7

Why are grooves present on bones?

Answer 7

Pressure form nerves and blood vessels

Question 8

Mechanical functions of bone (3)

Answer 8

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.

Question 9

What is the function of erythropoietin?

Answer 9

Erythropoietin is released from the kidney when blood oxygen levels are low (e.g., anaemia) to stimulate red blood cell production

Question 10

Define: SAD
Synarthrosis
Ampiarthrosis
Diarthrosis

Answer 10

By classification, a joint may be immovable (synarthrosis), slightly movable (amphiarthrosis) or freely movable (diarthrosis).

Question 11

Give examples of fibrous and cartilaginous joints

Answer 11

Fibrous joints – sutures (tight union between bones of the adult skull) syndesmoses (bones held together by fibrous tissues – interosseous membrane between long bones of the forearm & leg). Ghomphosi Cartilaginous joints – primary cartilaginous (epiphyseal growth plate in long bones) secondary cartilaginous (introvertebral discs)

Question 12

What are the three main components of a synovial joint?

Answer 12

Articulating surface, capsule, membrane

Question 13

What restricts movement at a synovial joint?

Answer 13

Ligament tension, muscle tension, interference of other structures (e.g. bony prominences)

Question 14

What part of a joint is affected in OA?

Answer 14

Cartilage

Question 15

What part of a joint is affected in RA?

Answer 15

Synovium

Question 16

Describe the three different types of cells found in bone

Answer 16

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).

Question 17

Explain the problems of hyper and hypocalaemia

Answer 17

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.

Question 18

Explain the role of PTH on bone (2 main points)

Answer 18

1. PTH is released from the parathyroid gland in response to low calcium levels in the blood. The role of PTH is to take up calcium from bone, kidney and intestinal tract to return plasma calcium levels to normal.
2. It also increases number and activity of osteoclasts in bone to increase calcium resorption from bone and stimulate release of minerals into blood.

Question 19

Explain the role of calcitonin on bone

Answer 19

released from specific thyroid cells (parafollicular) in response to elevated calcium levels in the blood.

It acts by lowering calcium levels in the blood by inhibiting osteoclastic activity in bone and favouring calcium uptake by bone to promote bone formation and decrease blood calcium levels.

It effectively does the opposite of PTH

Question 20

How does calcium and phosphate levels decreasing effect bone?

Answer 20

Calcium and phosphorous make up half of bone mass and are an essential nutrition for bone. Their deficiency causes bones to become brittle.

Question 21

What is the effect of vitamin A deficiency on bone?

Answer 21

Imbalance of ratio of osteoblasts and clasts to slow growth rate.

Question 22

What is the effect of vitamin C deficiency on bone?

Answer 22

Low levels of vitamin C inhibit growth to cause insufficient production of collagen (needed for hydroxylation of collagen in production) and bone matrix. This delays bone healing.

Question 23

What therapy can be used for osteoporosis?

Answer 23

Bisphosphonates and calcitonin both inhibit osteoclast activity. Calcitonin also stimulates osteoblast activity and favours calcium uptake into bone.

Question 24

Describe pagets disease

Answer 24

Progressive bone destruction disease followed by formation. this causes thickening of bones, usually of the skull, pelvis and lower extremities. Most common in over 60s.

Question 25

How would you classify the carpal bones?

Answer 25

Irregular

Question 26

What are pec major and minor innervated by?

Answer 26

Major by medial and lateral pectoral nerves (C7, C8, T1)

Minor by medial only

Question 27

What movements of the upper limb does pec major do?

Answer 27

Flexion of humerus
Adduction of humerus
Medial rotation of humerus.

Note: If pec major were to be damaged then these movements would be COMPROMISED, but not PARALYSED. Since there are other muscles which contribute to these actions.

Question 28

Which structures in the axilla may be compressed by the coracoid process when lifting an arm above the head?

Answer 28

Subclavian vein, subcalvian artery, cords of brachial plexus

sVACbp

Question 29

A man has been painting his ceiling and as a result has compressed the structures in his axilla. Why, on examination does he have a weak radial and ulnar pulse?

Answer 29

Compression of subclavian artery means blood supply is compromised to upper limb.
Subclavian goes to axillary artery and then brachial artery. brachial artery splits in the cubital fossa into radial and ulnar arteries.

Question 30

What is the action of pec minor?

Answer 30

Depresses shoulder tip

Question 31

What process causes skeletal muscle relaxation?

Answer 31

Active transport of calcium ions back into SR

Question 32

Describe malignant hyperthermia

Answer 32

An inherited condition where general anaethetic administered to a patient causes skeletal muscle fasciculations and rigidity as well as a rise in temperature and body metabolism. Skeletal muscle is affected in this way due to a rise in cytoplasmic calcium levels in skeletal muscle from increased release from SR by a faulty calcium channel.

Dantrolene is the treatment for this problem and acts on skeletal muscle to block release of calcium from intracellular stores.

Question 33

Describe the signs of an increase in body metabolism

Answer 33

Fall in blood oxygen, rise in blood CO2, fall in blood pH, tachycardia, increased ventilation

Question 34

In the axilla, what is found in the axillary sheath?

Answer 34

Axillary artery and vein and cords and branches of brachial plexus

Question 35

What forms anterior wall of axilla?

Answer 35

Pec major and pec minor underneath

Question 36

What forms posterior wall of axilla?

Answer 36

teres major and lat dorsi

and subscapularis and scapula

Question 37

What forms medial wall of axilla?

Answer 37

Intercostal muscles and overlying serratus anterior

Question 38

What lies immediately posterior to sternoclavicular joint?

Answer 38

Brachiocepalic vein

Question 39

What is the purpose of the clavicle?

Answer 39

Acts as a rigid support to suspend the scapula and upper limb away from the thorax to allow maximum freedom of motion.

Question 40

What part of the brachial plexus is most in danger following a clavicular fracture?

Answer 40

Trunks and divisions

Question 41

What is the best way to assess any nerve damage following an injury?

Answer 41

Sensory testing of peripheral innervation, distally to injury. Do not attempt motor testing or movement of the injured area.