Intro to musculoskeletal anatomy

Question 1

What is an epiphysis of a long bone?

Answer 1

The articular region end of bone

Question 2

What is a metaphysis of a long bone?

Answer 2

The metaphysis is the narrow portion of a long bone between the epiphysis and the diaphysis. It contains the growth plate, the part of the bone that grows during childhood, and as it grows it ossifies near the diaphysis and the epiphyses.

Question 3

What is a diaphysis of a long bone?

Answer 3

The shaft or central part of a long bone.

Question 4

Name 3 characteristics of Sesamoid bones

Answer 4

Found within tendons
Reduce wear
Improve muscle efficiency

Question 5

Name 3 characteristics of Flat bones

Answer 5

Large surface areas for muscle attachment
Weight/force transfer region
Protection (pelvic girdle and skull)

Question 6

What is Wolff’s law and how is it associated with bone remodelling?

Answer 6

Bone is deposited and reabsorbed in accordance with the stresses placed upon it (it is able to remodel)

Less Stress = Less Bone

Question 7

What is the difference between the axial and appendicular skeleton?

Answer 7

Axial Skeleton

• Skull
• Ribs
• Sternum
• Vertebrae
• Sacrum
• Coccyx

Appendicular Skeleton

• Hip bones (of pelvic girdle)
• Pectoral girdle
• Limbs (upper & lower)

Question 8

During which weeks do the limb buds grow out of the developing embryo (post fertilisation)?

Answer 8

Weeks 4 and 5

Question 9

Describe how the nerve supply of a limb develops.

Answer 9

The somites associated with a limb migrate with it during growth and pull their nerve supply with them
Somites form skeletal muscle (myotome) and dermis of the skin (dermatome)

Question 10

What do the following limb defects do?
Phocomelia
Amelia
Meromelia

Answer 10

Phocomelia - ‘flipper’ like limb
Amelia - loss of a whole limb
Meromelia - loss of part of limb

Question 11

How does digit separation happen in fingers and toes?

Answer 11

Programmed cell death (apoptosis) by week 8

Question 12

What is the difference between syndactyly and polydactyly?

Answer 12

Syndactyly - condition of having some or all of the fingers or toes wholly or partly united whereas Polydactyly - having additional digits (Hrithik Roshan)

Question 13

What are some of the causes of limb abnormalities?

Answer 13

Prescribed medication (e.g. thalidomide)
Dietary (e.g. Retinoids or Vitamin A derivatives)
Mechanical (e.g. Amniotic bands occlude blood supply)

Question 14

Which limb (upper or lower) would have a wide range of movement and low strength?

Answer 14

Upper Limb = Range of movement in preference to strength

Lower Limb = Strength in preference to range of movement

Question 15

What is the function of a girdle?

Answer 15

Attaches limb to an axial skeleton

Question 16

What type of joint (fibrous or cartilaginous) are suture, gomphosis and syndesmosis?

Answer 16

Fibrous joints are connected by dense connective tissue consisting mainly of collagen. These joints are also called fixed or immovable joints because they do not move.

Question 17

What type of joint (fibrous or cartilaginous) are epiphysis, synovial and symphysis?

Answer 17

Cartilaginous joints are connected entirely by cartilage (fibrocartilage or hyaline). Cartilaginous joints allow more movement between bones than a fibrous joint but less than the highly mobile synovial joint.

Question 18

What is the function of the synovium?

Answer 18

(serous membrane) - Sheet of fibrous connective tissue that secretes synovial fluid. This membrane type also forms bursae and sheaths covering parts of tendons and ligaments

Question 19

What is the pectoral girdle?

Answer 19

The pectoral girdle is a mobile structure, containing the scapula and the clavicle (which attaches to the manubrium). Therefore it has only one joint with the axial skeleton.

Shoulder range of motion = high; Stability=low
The mobility of the pectoral girdle increases the overall range of upper limb motion

Question 20

What type of forces are transmitted via the clavicle?

Answer 20

Compressive forces

Question 21

Can anything (if so, what?) cause fractures in the scapula?

Answer 21

Very uncommon to have fractures in the scapula but can be caused due to high force trauma

Question 22

What is the pelvic girdle?

Answer 22

Pelvic girdle is a rigid ring of bone that is partly formed by the axial skeleton
Hip range of motion = medium; Stability=medium/high
The pelvic girdle provides a rigid connection with axial skeleton

Distributes weight of axial body to lower limbs
Enables locomotion & standing
Force transmission mostly via compression

Question 23

What are bursae?

Answer 23

Bursae are pockets of synovium & synovial fluid found in regions of friction and wear. Some bursae are isolated and some communicated with joint spaces.

Question 24

How can bursitis be treated?

Answer 24

Bursitis causes localised pain & tenderness to palpation

Can be aspirated/injected with steroid

Question 25

What are tendons surrounded by?

Answer 25

Tendons are surrounded by sheaths of synovial membrane at points of wear / friction / direction change Sheaths can be individual or shared.

Question 26

What does the common flexor sheath extend into?

Answer 26

the common flexor sheath through the palm and carpal tunnel into the proximal forearm, and into digit 5 (little finger)

Question 27

What is tenosynovitis?

Answer 27

Tenosynovitis is the inflammation of the fluid-filled sheath (called the synovium) that surrounds a tendon, typically leading to joint pain, swelling, and stiffness.

Question 28

What are nerve plexi?

Answer 28

Nerve plexi (plexuses) are regions where the ventral rami of spinal nerves join and exchange neurons

Question 29

If a spinal nerve entering a plexus is damaged, what kind of loss would be seen?

Answer 29

Dermatomal sensory loss

Question 30

If a nerve emerging from a plexus is damaged, what kind of loss would be seen?

Answer 30

Injury to a named nerve emerging from a plexus causes a cutaneous nerve area sensory loss

Question 31

What helps form compartments in limbs?

Answer 31

Thick deep fascia (connective tissue) wraps around muscles and forms compartments. Anterior compartment = Muscles are mostly flexor in function Posterior compartment = Muscles are mostly extensor in function

Question 32

What are retinacula and what is their function?

Answer 32

Retinacula = thick bands of fascia | Prevent tendon bowstringing (Keep tendons in proximity of a joint enabling functioning through range of joint motion)

Question 33

Why do Venae comitantes run alongside arteries and between muscles within the compartments of the limbs?

Answer 33

Venae comitantes are deep paired veins wrapped together with an artery in one sheath. The pulsations of the artery (during systole) promote venous return to the heart within the paired veins.