001 Organisational patterns of limbs Flashcards
what are the 3 components of limbs
Stylopod, Zeugopod, Autopod
what is the stylopod component of limbs?
- 1 single bone
- most proximal bone in limb
- e.g. humerus, femur
what is the zeugopod component of limbs?
- 2 bones
- middle bone in limb
- e.g. radius/ulna, tibia/fibula
what is the autopod component of limbs?
- multiple bones
- most distal bones
- e.g. carpals/metacarpals/phalanges (wrist and fingers), tarsals/metatarsals/phalanges (ankle and toes)
what is anterior and posterior?
- anterior = front e.g. face
- posterior = back e.g. back
what is medial and lateral?
- medial = closer to middle/midline e.g. heart
- lateral = further from the middle/midline e.g elbow.
what is proximal and distal?
- proximal = closer to the trunk of body e.g. humerus
- distal = further away from trunk of body e.g. fingers
what is the coronal/frontal plane?
- divides front and back of body
what is the transverse/axial plane?
- divides top and bottom of body e.g. CT scan (horizontal)
what is sagittal plane?
- divides left and right of body e.g. through the midline
how does limb development start in embryos?
- protuberances of segments of the body wall (stick out)
what are the dermatomes of the upper limbs?
- C5 - T1
what are the dermatomes of the lower limbs
- L1 - S3
give an overview of how limbs form in embryos in terms of ectoderm and mesoderm
- ectoderm creating a pocket = skeletal muscle and nerve innervation
- inside filled with and covered by mesoderm = bones, tendons, vasculature, fascia and dermis
what are tetrapods?
- vertebrates with 4 digited limbs
- evolved from fish
- all tetrapods have a stylopod, zeugopod and an autopod
what is the central axis?
- bone element of limbs
what is the postaxial border?
- border of the limb that is behind the central aixs ( posterior)
what is the preaxial border?
- border of the limb that is in front of the central axis (anterior)
in fish where are the dorsal muscles and which direction does it move?
- above the central axis
- moves fins upwards
in fish where are the ventral muscles and which direction does it move?
- below the central axis
- moves the fins downwards
how is the limb organisation different in 4 legged mammals compared to fish
- the limbs bend ( rotated 90 degrees around the central axis)
- upper and lower limbs rotate in opposite directions
- limbs are under the body
- forearm pronates to point fingers forward as elbow is backwards
what is pronation?
- twisting of the muscles and central axis in the forearm so that the fingers are facing forward despite the elbow being rotated backwards
describe briefly week 5,6,7,8 in limb development in embryos
- week 5 = limbs bud from trunk similar to fish
- week 6 = limbs grow and ben, elbows and knees point laterally hands and feet face trunk
- week 7 = limbs rotate 90 degrees rotation around their central axis but in opposite directions ( elbows point causally, knees crainally)
- week 8 = limbs rotate 90 degrees latero-medially, bringing the limbs underneath the trunk
give an overview of the adult dorsal/ventral muscle group distribution
- dorsal muscles = back, shoulders, back of arms, glutes, front of thighs, front of calves, feet
- ventral muscles = torso, forearms, pelvis, back of legs