1. Vertebrae and muscles of the back Univ. of Central Florida
Lecturer: Dr. M. Samsam
Univ. of Central Florida
Pictures from: K. Moore Human anatomy and
Platzer atlas and text book of human anatomy

2. Vertebral column Vertebral column forms the basic structure of
the trunk.
It consists of vertebrae and intervertebral
disks.
There are 7 cervical, 12 thoracic, 5 lumbar, 5 sacral
and 4-5 coccygeal vertebrae in human.
Intervertebral disks (fibrocartilage) between the
vertebrae, absorb shock, assure no friction
between the bones and facilitate the movements
of the vertebral column.

3. Curvatures of the vertebral column:
Lordotic curve
Kyphotic curve
Scoliosis

4. Different parts of a vertebra

5. Spinal cord and its blood vessels plus the meninges and the CSF.
*Content of the vertebral canal:
Spinal cord and its blood vessels
plus the meninges and the CSF.

6. Cervical Vertebrae:
First cervical vertebra is called Atlas, the 2nd is called Axis.
The 7th is called: Vertebra Prominens.
3rd, 4th,5th and 6th are similar.

7. *Characteristics of cervical vertebrae:
A- transverse foramen. B- bifid spinous process. C- small vertebral body.
D- large and triangular vertebral canal.
*Contents of the transverse foramen: Vertebral artery
(C3-C7)

8. Vertebral arteries: pass through the transverse
Vertebral artery
Vertebral arteries:
pass through the transverse
foramen of the 6 upper Cervical
Vertebrae.
They enter the skull through the
Foramen Magnum

9. Atlas (1st cervical V., C1)
Has: no spinous process, no body, small anterior arch and a larger
posterior arch. Anterior tubercle, Posterior tubercle, Large
vertebral foramen, 2 lateral masses.
Each mass has a superior and an inferior articular facet.
Atlanto-occipital joint (between atlas and occipital bone).

10. Axis (2nd cervical V., C2)
Has an Odontoid process (dens) with an anterior articular facet to articulate with
atlas, and a posterior articular facet for transverse ligament of atlas.
*Hangman Fracture in the arch of axis pushes the dens posteriorly
and compresses the brain stem, leading to death.
*Fracture of the dens is a typical fracture of C2.

11. Atlanto-occipital articulation (upper head joint):
Between superior articular facet of Atlas and Occipital condyles
Atlanto-Axial articulation (lower head joint):
Consists of median and lateral atlanto-axial articulations.
Securing ligaments:
Transverse ligament of atlas (between the two lateral masses).
Apical ligament of the dens (attaches to anterior margin of foramen magnum).
Alar ligaments (from dens to lateral margin of foramen magnum.
Etc…

13. Clinical tips: *cervical rib (20): when the costal element is
preserved independently. Usually bilateral,
if one sided, usually on the left side
*The presence of a cervical rib may cause
a triad of disorders:
A- Ischemic muscle pain due to compression
of the subclavian artery.
B- pain in the ulnar side of the forearm & hand.
C- palpable mass over the clavicle.

14. Thoracic Vertebrae: There are 12 thoracic vertebrae in human.
Important characteristics:
Have 2 articular facets (2 and 17) on their
lateral side (one on the body and the other
on the transverse process).
Spinous process is long and slopes posteroinferiorly.
Costo-vertebral joints:
The head of each rib articulates with 2 adjacent
vertebrae and the disk between them
Costo-transverse joints: between the tubercle
of the rib and the transverse process of it’s own
vertebra

15. Lumbar vertebrae: There are 5 lumbar vertebrae in human.
Characteristics:
Large body (1), kidney shape.
Long transverse process (5).
Relatively small vertebral foramen (15).
*Lumbar puncture:
Is done at L3-L5 region.
The intercrestal line (iliac crests) is at the
level of L4 approximately (safe region).

16. 11 and 12th ribs are floating ribs 1- head, 2- neck, 3- body
Ribs: 12 ribs
1-7 are the true ribs
The last 5 are false ribs
11 and 12th ribs are floating ribs
1- head, 2- neck, 3- body
4- tubercle
*Costal groove: contains the intercostal
nerve and vessels.
Head and the tubercle have articular
surfaces to articulate with the vertebrae

17. Sternum: Consist of: Sex differences: Body is longer, narrower
1- Manubrium, 2- body, 3- Xiphoid process
4- Sternal angle T4, 5- jugular (suprasternal)
notch, 6- clavicular notch, 8- notch for
articulation with 2nd rib,
Sex differences: Body is longer, narrower
and slimmer in males than in females
*Sternal puncture:
Bone marrow needle biopsy for transplantation or
cytologic analysis:
In the midline in the body of sternum between
2-3 ribs attachments
Never try in the lower 2/3 of the sternal body.
Median Sternotomy: in coronary bypass surgery
Congenital anomalies:
*Complete sternal cleft: associated with
ectopia cordis.
*Pectus excavatum (funnel chest)
*Pigeon chest
*Congenital sternal (10) fissure (sternal foramen).
*Aneurysm of the Aorta: pulsatile mass at
suprasternal notch (T2); arch is behind the manubrium.

18. Joints of the vertebral column:
*Zygapophysial joints (A-B)
These are the small vertebral joints between
the articular processes.
Uncovertebral joints:
Between cervical vertebrae. They develop
by age and may become pathologic and
permit disk herniation especially in C5 region.

19. Intervertebral disks:
Fibrocartilage tissue.
They consist of an outer tense part, the
Anulus Fibrosus (1) and a soft jelly-like nucleus
called the Nucleus Pulposus (remnant of the
Notochord, embryonic tissue).
Function:
Acts as a shock absorber, is compressible and
permits slight degree of movement of the
vertebrae over each other.
They build up approximately 20% of the length
of the vertebral column (taller in the mornings).
*Herniation:
Mostly posterolaterally where the Anulus
Fibrosus is thinner.

20. Disc herniation

21. Disc herniation

22. Ligaments of the vertebral column:
Many, among them,
Anterior longitudinal lig (1)
Post. Longitudinal lig (2)
Ligamentum flavum (5) , yellowish in color
due to Elastic fibers, facilitates movements
Intertransverse ligs (7)
Interspinous lig (8)
Supraspinal lig (10).

23. Sacrum:
Consists of 5 sacral vertebrae and the
intervertebral disks that lie between them.
It has a concave anterior surface (A) and a
convex dorsal surface (B).
Females: sacrum is wider, shorter, more concave.
Males: sacrum is longer and less wide.
*Sacral hiatus, Sacral horns (cornua)
*Epidural anesthesia is given through sacral
hiatus to block the pelvic nerves.

24. Epidural anesthesia

25. Coccyx:
Four vertebrae (rudimentary).
6- Cornua or horns of coccyx facing
sacrum.
Injury to coccygeal vertebrae:
Falling on buttocks, specially in females,
Painful delivery.
Coccydyna: pain in coccyx

26. Abnormal fusion and
defects of the vertebrae:
Sacralization of L5
Lumbarization of S1
*Spina Bifida:
Failure of vertebral arches to form or fuse.
Usually In lumbar or sacral vertebrae
Leading to meningocele (just meninges bulge
out of the vertebral canal) or
meningomyelocele (meninges plus
spinal cord bulge out).
Spina bifida Occulta:
*Folic acid substitution in conception and
during pregnancy decreases the risk of
spina bifida.

28. Congenital anomalies (continued):

29. Muscles of the back: Cranial muscle inserted on the Shoulder girdle:
1- Trapezius M: has 3 parts:
2- Descending part
3- Transverse part
4- Ascending part
Descending part:
Origin: from external occipital protuberance,
superior nuchal line, and Ligamentum nuchae
Insertion: lateral third of the clavicle
Transverse part: from C7-T3 spinous process
Inserted to: clavicle and scapula (acromion)
Ascending part: from T3-T12 spinous process
Insertion: spine of the scapula
*Function: elevation, retraction and rotation
of scapula.
Helps in adduction and slight elevation of arm
**Innervation: spinal root of Accessory nerve
(CNXI) and C3-C4 (propioception and pain).

30. Back muscles inserting on the
shoulder girdle
Rhomboid Minor (1):
Origin: spinous precess of C6 and C7 (2).
Insertion: medial margin of scapula (3).
Rhomboid Major (4): caudal to Rh. minor
Origin: spinous process of T1-T4 (5)
Insertion: medial margin of scapula (3)
*Function of both muscles: press the scapula
to the thoracic wall, retraction of scapula medially.
Nerve supply: dorsal scapular nerve (C4-C5)
Levator Scapulae(6):
Origin: transverse process of C1-C4
Insertion: superior angle of scapula
Function: elevates the scapula
Innervation: dorsal scapular nerve (C4-C5)

31. 12- Latissimus dorsi M: (coughing M)
Has many parts:
Origin:
13:vertebral part T7-T12 spinous process
14:thoracolumbar part (from fascia)
15:iliac part (from iliac crest)
16:costal part: 10-12th rib
17- inferior angle of scapula
Insertion: crest of the lesser tubercle
of humerus (18).
*Function:
Adduction and lowering the arm, medial
rotation and extension of the arm (humerus).
Raises the body toward the arm when climbing.
*Innervation:
Thoracodorsal N. (C6, C7, C8).

32. 5- Serratus post. Inferior
Innervation: intercostal nerves (T9-T12).
12- Serratus post. Superior
Function: rib elevation
*Both may function as accessory muscles of
respiration (in COPD).

33. Intrinsic muscles of the back
(erector Spinae)
2 groups:
Lateral (superficial) group
Medial deep group.
**Lateral group:
Iliocostalis (1,2,3), lumborum, thoracis, cervicis
Longissimus (4,5,6) thoracis, cervicis, capitis
Splenius crvicis (11) and capitis (12)
*Innervation: all by primary spinal dorsal rami
*Function: for erect posture of the body and
the two splenii rotate the head.
Extensors when both sides contract and flexion
when one side contracts.

34. Medial group
Interspinales Muscles (1,2,3)
Intertransverse muscle (4) cervicis
and lumbar (5).
Spinalis Thoracis (6) and Cervicis (7) and
perhaps capitis as well.
Rotator brevis (8) and longus (9) thoracis
Multifidus (10)
Semispinalis cervicis (11) and capitis (12)
All innervated by various primary dorsal rami.
Function: Extensors when both sides contract
and flexion when one side contracts.
Some stabilize and some rotate the
vertebral column.

37. 1- rectus capitis posterior minor muscle
**Suboccipital triangle
2- rectus capitis post. Major
3- Oblique capitis superior
4- Oblique capitis inferior
**Content:
A- 3rd part of vertebral artery,
B- Suboccipital nerve (C1) innervating
all 3 muscles
C- Suboccipital plexus of veins
Function: turning the head backward or
laterally.
**Vertebrobasilar syndrome
Sensory innervation of the region:
Greater occipital nerve (C2)

38. Suboccipital triangle content

39. Atlas