Ch 2-Back: Component parts

Question 1

-Bones:

Answer 1

• 33 vertebrae: -7 cervical, -12 thoracic -5 lumbar -5 sacral -3-4 coccyx
  - Ribs articulate via synovial joints w/ transverse processes

Question 2

-A typical Vertebra:

Answer 2

• Vertebral Body-increases in size from CI to LV
  - Vertebral arch:
  - anchored by 2 pedicles.
  - Roof formed by R/L laminae.
  - Spinous process=muscles/ligaments
  - Transverse Process=ribs
  - Superior/Inferior articular process=adjacent vertebrae
  - Superior/Inferior vert notch= forming intervertebral formina
  - Attachments for muscles, ligaments
  - Levers for muscle action
  - Sites of articulation with adj vertebrae.

Question 3

-Cervical: Foramen transversarium

Answer 3

• Atlas: Lacks vert body.
  - Lateral masses articulate w/ occipital condyles
  - Atlanto-occipital joint: head to nod up and down
  - Dens facet= dens held by transverse ligament of atlas
  - Transverse process=levers for muscles move head at atlanto-axial joints
  - Axis: Large, toothlike dens
  - Alar ligaments on dens, that connects to medial surfaces of occ. Condyle

Question 4

Thoracic

Answer 4

• 2 facets-Superior/Inferio costal facet-for own head of rib and head of rib below
  - Transverse costal facet-tubercle of own rib

Question 5

Sacrum

Answer 5

1 bone=5 fused sacral vert.

		- concaved anteriorly
		- L-shaped facet for pelvic bone
		- 4 pairs post sacral foramina, 4 pairs ant sac foram for ant/post rami

Question 6

Coccyx

Answer 6

articulates with sacrum = 3-4 coccygeal vert.

Question 7

Lumbar:

Answer 7

• Thin, long transverse process except at LV
  - iliolumbar ligaments to connect w/ pelvic bones
  - lack rib facets-

Question 8

Extrinsic muscles

Answer 8

upper limbs, thoracic wall

			- anterior rami of spinal nerves
			- Trapezius
			- Levator scapulae
			- Rhomboid minor/major
			- Latissimus dorsi
			- Serratus posterior inferior and posterior superior

Question 9

Intrinsic muscles

Answer 9

support&move vertebral col, head, ribs

			- Post. Rami of spinal nerves
			- Suboccipital
			- Splenius
			- Erector spinae: Longissimus, Iliocostalis, Spinalis

Question 10

• Vertebral Canal: spinal cord, lies within bony canal

- surrounded by 3 connective tissue membranes (meninges)

Answer 10

• Pia Mater-innermost
  - denticulate ligament, on each side laterally fr cord to arachnoid/dura mater. Positions cord.
  - >subarachnoid space<- extends past spinal cord, to SII. CSF withdrawn.
  - arachnoid trabeculae interconnect.
• Arachnoid mater-secondmost
  - Ends at SII
• Dura mater-most external → extradural (epidural) space
  - periosteum-1 layer fused to bone
  - as spinal nerves/roots pass laterally, they are surround which merge to become part of outer covering (epineurium)
  - Superficial fascia-between skin and spinous process
  - Lumbar punctures adj vert spinous process, through supraspinous/interspinous ligament, and extradural space. Then thru dura and arach, finaly subarachnoid.

Question 11

-Spinal Nerves: 31 pairs, emerge from vert canal between pedicles.

Answer 11

• C1-C8
• T1-T12
• L1-L5
• S1 – S5
• Co
• Ramus → Spinal Nerve → Roots → rootlets (medially)
  - Post root-info to CNS w/ sensory neurons, with clustered spinal gang.
  - Ant root-info away from CNS w/ motor neurons
  - >medially, spinal segments => rootlets

    - Each nerve connects to spinal cord by a post/ant root
    - @ vert canal exit, each spinal nerve branches into:
        - Post ramus-innerv back (intrinsic)
        - Ant ramus-innerv most other body except head.
                - major somatic plexus(cervical, brachial, lumbar, and sacral)
                - Pns visera (sympathetic trunk, prevert plexus)
    - to supply dura, ligaments, interdisks, vessels :meningeal(sinuvertebral) nerves ← 
    - Below end of cord, roots pass inferiorly to exit points from canal-cauda equina cluster

Question 12

-Dermotomes/Myotomes:

Answer 12

-Derived from somites. (sclerotomes form vertebra)
-Each spinal nerve develops in association w/ somite and innervates specific strip of skin and group of skeletal muscle fibers
Dermatome=area of skin
Myotome=region of skeletal muscle

Question 13

-Relationships to other regions-

Answer 13

• Head: cervical back supports and moves head and neck
  
  • Thorax, abdomen, and pelvis: provide attachment for muscles and fascia, and other bones. Ant rami pass through here.
  • Limbs: back bones give extensive attachment for muscles in moving upper limbs. Sacral bones anchor lower limbs.