Parts of Spine

Spine

Parts of a spine:

Cervical Curve: 7 vertebrates (forms a convex curve)

Thoracic Curve: 12 vertebrates (forms a concave curve)

Lumbar Cuve: 5 vertebrates

Sacral Curve: 5 vertebrates

Kyphosis & Lordosis

Kyphosis refers to the natural curvature of the upper spine (primary curves in thoracic & sacrum)

Lordosis refers to the natural curvature of the lower spine (secondary curves in cervical & lumbar)

(Hyper in the prefix means extreme curvature of these)

Typical Vertebrae (Posterior/Anterior View)

Vertebral body: supports body weight and protects spinal cord

Pedicle: Connects to the lamina to make the vertebral foreman

Lamina: Connects to the pedicle to make the vertebral foreman

Vertebral foreman: the spinal cord goes in this hole

Transverse processes: attachment points for muscles and ligaments to stabilize spine

Spinal Processes: attachment point for muscles and ligaments to stabilize spine

Typical Vertebrae (Lateral View)

• Superior articular process → Connects with another vertebrae’s inferior articular process, helps limit spinal movement from bending too back.

• Superior articular facet → where a joint forms to connect other vertebrae

• Superior articular notch → indentation that helps form the intervertebral foramen, where spinal nerves pass through.

• Inferior articular process → Connects with another vertebrae’s superior articular process; helps stabilize movement.

• Inferior articular facet → where a joint forms to connect other vertebrae

• Inferior vertebral notch → indentation that helps form the intervertebral foramen for spinal nerves to pass through.

• Vertebral body

• Spinous process

Invertebrate Discs between vertebral body

Nucleus pulposus: soft, gel like centre of the disc that acts as a cushion for vertebral body

Annulus fibrosis: tough, fibrous ring that holds the nucleus in place, resists tensile & twisting forces

How does it work during movement?

Lying down:
Less body weight → disc is relatively thicker.

Standing:
Body weight compresses the disc → it becomes shorter/thinner

Lateral flexion:

One side of the disc is compressed, the opposite side is stretched

Spinal Ligaments

Anterior longitudinal ligament:

• Covers the vertebral bodies and discs anterolaterally.

• Extends from sacrum to occipital bone

• Helps maintain stability of disc joints

Posterior longitudinal ligament: Extends from axis to sacrum. Helps prevent excessive flexion (bending forward).

Ligamentum flavum: Joins laminae of other vertebrae. Helps limit excessive flexion and helps the spine return toward its normal position after bending.

• Supraspinous ligament: runs along the tips of the spinous processes. Helps limit excessive flexion.

• Interspinous ligament → runs between the spinous processes. Also helps limit excessive flexion.

Cervical Vertebrae (anterior/posterior view)

• Foramen transversarium → hole in the transverse process; vertebral arteries pass through it (mainly C1–C6).

• Small vertebral body → smaller than the vertebral bodies of the thoracic and lumbar spine because they carry weight of head.

• Bifid spinous process → spinous process is split into two parts at the tip, especially C2–C6. Attaches to ligaments and muscles

• Articular facets: 45° oblique → connects to otherallows flexion, extension & rotation

C1 & C2

• C1 (atlas):

• Interior tubercle → Small bump at the front; provides attachment for muscles/ligaments.

• Posterior tubercle → Small bump at the back; provides attachment for muscles/ligaments.

• Large superior articular facets → Connect with the occipital joints of the skull → allow the head to nod up and down (“yes” motion).

• Attachment point anteriorly for transverse ligament → The transverse ligament holds the dens of C2 against C1, keeping it stable.

• C2 (axis):

• Bifid spinous process → Split spinous process; provides attachment for muscles and ligaments that help move/stabilize the neck.

• Odontoid process (dens) → A tissue that acts as a pivot for C1 and the skull → allows horizontal rotation of the head.

• Minimal transverse processes → provide attachment points for muscles/ligaments.

Thoracic Vertebrae (lateral view)

Superior demifacet: connects to the head of the rib above

Inferior demifacet: connects to the head of the rib below

Transverse facet for rib: connects to the tubercle of rib

Lumbar Spine (anterior/posterior view)

Sacrum & Coccyx

• Base: the top part of the sacrum. Connects with L5.

• Apex: the bottom point of the sacrum. Connects with the coccyx.

• Anterior sacral foramen: openings on the front of the sacrum where sacral spinal nerves and blood vessels pass through.

• Coccyx: small tailbone below the sacrum; provides attachment for muscles and ligaments and helps support the pelvic floor.

• Auricular surface: Connects with the ilium of the pelvis (hip bone)

Parts of sternum

Manubrium: The superior part of the sternum and attaches to 1st rib. The central part is the suprasternal notch, the sides are the clavicular notches, where clavicles attach.

Sternum: sternal angle to xiphoid. attaches from 2nd-7th rib

Xiphoid: Bottom part of sternum. Attachment points for ligaments and muscles.

True, false, floating ribs

True (vertebrosternal) ribs: 1st-7th rib attached to sternum anteriorly through costal cartilages

False (vertebrochondral) ribs: 8th-10th ribs: have cartilages on their anterior ends that attach to the superior cartilage

Floating ribs: 11th-12th ribs that have small cartilages on their anterior ends that don’t connect

Typical ribs

Head:

Neck:

Costal Angle:

Tubercle:

Costal Groove:

Facets for Vertebrae:

Facet for costal cartilage:

Ribs & Sternum Joints

Sternocostal joints: costal cartilages attached to sternum (Most are synovial plane joints, expect 1st rib)

Costochondral joints: costal cartilages attached to ribs

Costalvertebral joints: head of the rib that connects to the vertebral body

Costotransverse joints: tubercle of the rib that connects to the transverse processes