Axial Skeleton (Vertebral Column)

Question 1

Spine (How many bones in total and how many in each section?)

Answer 1

• 24 pieces of bone stacked on top of another (numbered in roman numerals)
• in an anterior view (left) there is no curvature but in a side, lateral view there is
• cervical: 7 vertebrae
• thoracic: 12 vertebrae
• lumbar: 5 vertebrae
• sacral: 1 (5 pieces that are fused together) called sacrum - can identify them separately
• coccygeal: coccyx

Question 2

Regions: Primary and Secondary Curvature

Answer 2

• curvature is not present at time of birth - not all of them, a few of them are
• in a fetus you can still see the columns but there is no significant curvature
• you have two curvatures at time of birth: sacral and thoracic (identified as primary curvatures: curvatures present at time of birth)
• cervical and lumbar curvature are gained after birth (developed after)
• cervical develops around time when baby learns to keep head and neck steady (age: 2-3 months)
• lumbar curvature develops much later when kids start walking around (age: 1-1.5 years)
• cervical and lumbar curvature are classified as secondary curvature as there are not present at time of birth

Question 3

Kyphosis

Answer 3

• curvatures can exaggerate beyond their normal ranges
• exaggerated thoracic curvature

Question 4

Lordisis

Answer 4

• exaggeration of lumbar curvature that naturally happens during pregnancy
• do not use this term for normal range

Question 5

Scoliosis

Answer 5

• usually no curvature in anterior and posterior view - should be straight
• slight range of side curvature which is known as scoliosis is present in almost everyone - 5 degrees of scoliosis (side bending of spine) - reflects what side you write with (you carry more on that side) so you will bend more to that side
• when it increases over 5 it is a pathological case - treatment can vary: exercise, brace or even surgery

Question 6

Features of Typical Vertebrae (ones that have things in common)

Answer 6

• typical vertebrae from lumbar region
• big bony mass in front of vertebrae - body
• bony arch behind body which is called vertebral arch
• between the body and the vertebral arch there is a hole is called vertebral foramen which form vertebral canal when stacked on top of one another (which contains the spinal cord)
• arch is made by different pieces:
  ◦ pedicle (small foot) - pair of
  thick bony plates
  ◦ lamina (plate) - two of them
• at the junction of pedicle and lamina there is a bony process extends laterally called the transverse process (not palpable)
• when the two lamina reach each other posteriorly at the midline together they fuse and create another process called spinous process (palpable)
• articular processes will articulate or join the adjacent vertebrae together (superior and inferior)
  ◦ the inferior articular process of the superior vertebrae is articulating with the superior inferior process of the inferior vertebrae (making a joint between them)

Question 7

Typical Cervical Vertebrae (smaller) - What is the specific Feature

Answer 7

• specific feature: the spinous process of a typical cervical vertebrae is split so it called bifid spinous process
• you see presence of a hole that is present on the transverse process and it carries a hole

Question 8

Two Atypical Cervical Vertebrae - Axis and Atlas

Answer 8

1st: Atlas (superior view)
- does not have a body instead it has an anterior arch
- no lamina either but rather a posterior arch
- has a transverse process and a hole like other cervical vertebrae
- no spinous process posteriorly
- has big mass of bone called lateral masses which carries articular processes for condylar processes of the occipital bone
- superior articular facet
* 2nd: C2 also known as Axis
- sticking out of body there is a bony process which is called dens axis or deltoid process
- it articulates with the anterior arch of the axis which allows us to rotate our neck (big part of the rotation of neck is due to joint between C1 and C2)

Question 9

Typical Thoracic Vertebrae (Lateral)

Answer 9

• carry some articular facets because they articulate with ribs that are not present in other vertebrae
• smooth articular processes are only present in thoracic vertebrae as there are the only ones that articulate with ribs
• when you put two typical thoracic vertebrae together they create foramen (intervertebral foramen) which creates passages for spinal nerves seen on the lateral view - as they arise from the spinal cord in order to exit the vertebral canal this creates the passage
• specific feature: length and direction of spinous process is very long and always points inferiorly

Question 10

Typical Lumbar Vertebrae

Answer 10

• shape of the body: kidney shaped and they have the largest body
• specific feature: very thick and short spinous process

Question 11

Sacrum (Anterior View)

Answer 11

• one piece of the sacrum at the very top one can fail to fuse and they have one extra lumbar vertebrae (L6)
• the opposite is also true where L5 fuses with rest of sacrum and they only have 4 lumbar vertebrae
• messes with the biomechanics and can cause severe low back pain - more common in females
• when sacrum losses one of its segments to the lumbar area it is known as lumbarization clinically
• sacrumization when you lose lumbar vertebrae to the sacrum
• wedge shaped
• body of S1 is seen from a superior view
• on either side of the body of S1 you can identify triangular surfaces which are known as sacral ala (wings)
• distal ends: apex of the sacrum articulates with the coccyx
• horizontal ridges separate the bodies - are reminent of the intervertebral discs
• anterior part: promontory is the most prominent part of the sacrum that enters into the pelvic cavity
• spinal nerves pass through the anterior sacral foramina

Question 12

Posterior Surface of the Sacrum

Answer 12

• rough and has a lot of crests - are reminent of the spinous processes called sacral crests
• at distal end of sacral crust there is a reverse U-shaped notch known as the sacral hiatus - the end of the vertebral canal - sealed with a layer of fibrocartilage
• sacral canal is the continuation of the vertebral canal - superior view
• on either side of the sacrum there is an articular surface called the oracular surface which articulates sacrum to the hip bone

Question 13

What are the Different Components of the Sternum?

Answer 13

• ribs 1-7 attach to sternum
• sternum is composed of 3 parts:
  ◦ highest part of sternum is
  called manubrium (handle of
  the dagger)
  ◦ body of sternum
  ◦ most distal part is called the
  xiphoid process
• jugular notch is also known superasternal notch: highest bony notch you can touch (beginning of the manibrium)
• where the manibrium and body of your sternum join together they create a bony horizontal ridge
• sternal angle (important bony landmark) passes through intervertrebral disc T4-T5 where a lot of things happen
• where the body of the sternum joins with the xiphoid process that would be called the xiphisternal joint (these joints over the age of 60 turn into bone)

Question 14

True and False Ribs and Floating Ribs

Answer 14

• true ribs are directly joining to the sternum (first 7)
• 8-10 are reaching sternum indirectly through cartilage of rib 7 - referred to as false ribs
• rib 11-12 are known as free or floating ribs as they have no attachment to the sternum

Question 15

Features of a Typical Rib

Answer 15

• posterior end is where head is
• immediately after head is neck (narrow)
• rib sharply bends after neck - most common site for fracture of the rib called costal angle
• body is more anterior
• on lower body is called the costal groove (occupied by blood vessels and nerves)