Lecture 5 (FIRST MIDTERM) Flashcards
Functions of the axial skeleton (general):
Support
Protection
Respiration (VENTILATION)
The vertebral column comes from…
the somites
Somites migrate ventrally to the notochord and do what?
fuse to each other and break up the notochord into segments
The notochord now exists where?
in between the somites (now sclerotomes; vertebral bodies)
Remember…
Somites break up into what 3 categories?
Dermatome
Myotome
Sclerotome
*If you don’t remember what they turn into next, then go back and master the other decks >:(
The myotome that comes from a somite (sclerotome) and connects to the same somite (sclerotome) cannot cause movement. Why?
Because the muscular structure is NOT crossing a joint
Each sclerotome has a line of separation. How is each sclerotome labeled?
Superior portion and inferior portion
When the line of separation “splits” the sclerotomes, what happens to them? What about the myotomes?
The superior portion fuses with the inferior portion from above it. The myotomes DO NOT split.
CONNECTION TIME!
When each sclerotome fuses with the portion above it, what can now happen?
The myotomes can now produce movement because they are now crossing a joint!
After the sclerotomes fuse with the portions above them and the myotomes cross joints, what’s the last fusion that must occur?
Each pair of the sclerotomes moves toward the middle toward the notochord and fuses with each other and CHOPS UP the notochord into pieces.
Does the Dorsal hollow nerve tube get chopped up? Why or why not?
No, it is protected by a “bony canal”
The notochord develops into what?
Part of the intervertebral disc (not the entire thing)
What is really being protected, the notochord or the dorsal hollow nerve tube?
Not the notochord - it gets chopped up!
The dorsal hollow nerve tube gets protected
What does it mean to have a homolog?
It shares a common origin; derived from the same tissue
Serial homologs:
A series of structures that came from the same thing
example: all vertebrae are serially homologous to each other
Intervertebral foramina allow what?
They allow peripheral nerves to emerge and go out to the body
Intervertebral discs are made of what on the outside and then what in the middle?
Fibrocartilage pad (anulus fibrosus) on the outside Nucleus pulposus in the middle
What is the only little piece left from the notochord?
The nucleus pulposus
When you put extreme pressure on your vertebrae, you can actually weaken the anulus fibrosus and push out some of the nucleus pulposus. Why is this bad? What can happen?
Called a herniated disc
It can put pressure on an emerging nerve or the central nervous system itself; can damage it
What do cervical vertebrae have that is unique?
transverse foramen
also bifid spinous process
What runs through the transverse foramen?
Vertebral artery, vertebral vein, and vertebral nerve
What is C1? C2?
C1: Atlas
C2: Axis
Joint name when you nod “yes”
Joint name when you shake your head “no”
"Yes" = Atlanto-occipital joint "No" = Atlas-axis joint
What do thoracic vertebrae have that is unique? What do they do?
costal facets
articulates with ribs
How many of these costal facets? Name them.
3
Superior costal facet
Inferior costal facet
Transverse costal facet
Ribs identification -
Head:
Body:
Tubercle:
Head: part that articulates with thoracic vertebrae
Body: lost part (shaft)
Tubercle: below the neck
A rib actually articulates where?
In between vertebral bodies; intervertebral discs
The head of the rib and the rib tubercle create what kind of action?
a hinging action
Median sacral crest is homologous to:
Spinous processes of vertebrae
Promontory of sacrum is homologous to:
Body of vertebrae
Ala is homologous to:
Transverse foramen of vertebrae
Spinal nerves emerge from where?
Intervertebral foramina in between the vertebrae
Spinal nerves numbering Cervical: Thoracic: Lumbar: Sacral:
Cervical: 8 (starts on top, ends on bottom)
Thoracic: 12
Lumbar: 5
Sacral: 5
Regions of sternum from top to bottom:
Manubrium
Body
Xiphoid process
True ribs:
False ribs:
True ribs: ribs 1-7
False ribs: ribs 8-12
What does the hyoid bone belong to?
axial skeleton
Limbs are multisegmental. How many segments are they usually derived from?
6
The pectoral girdle is ___________ to the body wall while the pelvic girdle temporarily ___________ the body wall.
superficial; interrupts
The pectoral limb attaches to ________ aspect of body wall while the pelvic limb attaches to ________ aspect of body wall.
dorsal; ventral
Is the hip bone axial or appendicular?
Appendicular
Brachium is homologous to:
Femur, thigh
Antebrachium is homologous to:
Grus
Manus is homologous to:
Pes
Pectoral girdle is homologous to:
Pelvic girdle
The os coxa is homologous to:
Scapula
The femur is homologous to:
Humerus
What is the portion between the knee and the ankle referred to?
The crural region (the crust)
The 2 bones of the crural region:
tibia and fibula
The fibula is homologous to:
Ulna
The tibia is homologous to:
Radius
Trapezium is homologous to:
Medial cuneiform
Trapezoid is homologous to:
Intermediate cuneiform
Capitiate is homologous to:
Lateral cuneiform
Hamate is homologous to:
Cuboid
Scaphoid is homologous to:
Navicular
Lunate is homologous to:
Talus
Triquetral and pisiform are together homologous to:
Calcaneus
Medial cuneiform is homologous to:
Trapezium
Intermediate cuneiform is homologous to:
Trapezoid
Lateral cuneiform is homologous to:
Capitate
Cuboid is homologous to:
Hamate
Navicular is homologous to:
Scaphoid
Talus is homologous to:
Lunate
Calcaneus is homologous to:
Triquetral and pisiform together
On the first digit of the foot (pes) and the hand (manus), there are how many phalanges?
two; proximal phalanx and distal phalanx
How many phalanges on the other digits
three; proximal, middle, distal
