A&P LAB - Lesson 5 (Spine & Ribs)

What are the 3 parts of the axial skeleton?

1. Skull (cranium & facial bones)

2. Vertebral Column

3. Bony Thorax

What are the 3 parts of the vertebral column?

1. 24 vertebrae

2. sacrum

3. coccyx

What are the vertebrae separated by?

intervertebral discs made up of

How are the vertebrae grouped?

• 7 Cervical

• 12 Thoracic

• 5 Lumbar

C1

• atlas

• lacks body and spinous process

• allows head to nod

C2

• axis

• has den (odontoid process) for head rotation

C1-7 distinguishing features

• triangular vertebral foramen

• transverse processes contain foramen/foramina for vertebral arteries traveling to brain

C7

• vertebra prominens

• landmark for counting vertebrae

T1-12 distinguishing features

• heart shaped body

• small articulating surfaces/costal facets (superior & inferior) articulates with head of rib

• round/oval vertebral foramen

• transverse costal facets (on transverse process) articulated with rib tubercles

L1-5 distinguishing features

• block-like body & short thick spinous process

• superior articular process pointing posteromedial

• inferior articular process pointing anterolateral

Where does the spinal cord end?

superior area of L2

Where are spinal/lumbar taps and epidurals performed?

between L3 & L4 or L4 & L5 to minimize injury to spinal cord

Intervertebral foramen

• between the inferior notch of a superior vertebra and the superior notch of an inferior vertebra

• for nerves to enter or exit the spinal cord

Sacrum

formed by fusion of 5 bone

Prominent features of sacrum

• sacral promontory

• median sacral crest

• ala

• transverse ridges

• anterior/posterior sacral foramina

Sacral promontory

at anterior border of S1

Median sacral crest

remnant of fused spinous processes

Ala

formed by fusion of transverse processes

Transverse ridges

site of vertebral fusion

Anterior/Posterior sacral foramina

passage for blood vessels and nerves

Coccyx

• “tailbone”

• formed by fusion of 3-5 irregularly shaped vertebrae

• attached to sacrum by ligaments

Primary curvatures

present at birth (thoracic & sacral curvatures)

Secondary curvatures

develop after birth (cervical & lumbar curvatures)

What are the 2 types of secondary curvatures?

Cervical curvature: allows baby to hold head up

Lumbar curvature: allows baby to walk

Scoliosis

lateral thoracic spine curvature

Kyphosis

excessive posterior thoracic curvature

Lordosis

excessive lumbar curvature

What is the bony thorax composed of?

1. sternum

2. ribs

3. thoracic vertebrae

Sternum

“breastbone”

• attaches to the 1st 7 pairs of ribs

What 3 bones form the sternum?

1. manubrium

2. gladiolus (body)

3. xiphoid process

Manubrium

articulates with clavicle

Gladiolus (body)

bulk of sternum

Xiphoid process

• located at the inferior end

• made of hyaline cartilage in children

What are the 3 important landmarks of the sternum?

1. jugular notch

2. sternal angle

3. xiphisternal joint

Jugular notch

at the level of the 3rd thoracic vertebra

Sternal angle

at the level of the 2nd ribs and 5th thoracic vertebra

Xiphisternal joint

at the level of the diaphragm and 9th thoracic vertebra

How many pairs of ribs do we have?

12

True ribs

• vertebrosternal ribs

• ribs 1-7

• attach to the sternum thru their own costal cartilage

False ribs

• vertebrochondrial ribs

• ribs 8-12

• ribs 8-10 attach to sternum thru costal cartilage of rib 7

• ribs 11-12 floating/vertebral ribs do not attach to sternum

Thoracic vertebrae

serve as an anchoring site for the ribs