Bones of Trunk (Human Anatomy)

BY:BY:
DR RAI M. AMMAR MADNIDR RAI M. AMMAR MADNI
( M.B.B.S , RMP )

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BY:BY:
DR RAI M. AMMAR MADNIDR RAI M. AMMAR MADNI
( M.B.B.S , RMP )( M.B.B.S , RMP )

Bones of trunk
Composition:
oVertebral Column
(vertebrae, sacrum, coccyx),
oThoracic Cage
(sternum and ribs)

Divided into five major regions
Cervical vertebrae
7 vertebrae of the neck region
Thoracic vertebrae
12 vertebrae of the thoracic
region
Lumbar vertebrae
5 vertebrae of the lower back
Sacrum( 5-fused)
Inferior to lumbar vertebrae
Articulates with coxal bones
Coccyx (3-4 fused)
Most inferior region of the
vertebral column
Vertebral Column
(Regions)

The Vertebral Column
Extends from lower end of skul to the pelvis.
About 70 cm (28 inches) in length,
Located in the mid-dorsal region and forms the vertical
axis.
Consists of a series of bones, the vertebrae, separated
by fibrocartilagenous intervertebral disks
Transmits weight of trunk to the lower limbs
Surrounds and protects the spinal cord
Serves as attachment sites for muscles of the neck and
back
Supports the thoracic cage and serves as a point of
attachment for the pelvic girdle.
Vertebrae increase in size from cervical to lumbar region
due to lower back having to support more weight
Held in place by ligaments
 Anterior and posterior longitudinal ligaments
 Ligamentum flavum

Four spinal curvatures give
vertebral column an S-shape
Primary (accommodation)
curvatures : thoracic and sacral, convex
posteriorly
 Appear in fetal development /
accommodate the thoracic and
abdominal viscera
Secondary (compensation) curvatures
: lumbar and cervical,
concave posteriorly
 Appear when a baby begins to walk
 Help shift weight from trunk to lower
limbs
The Vertebral Column
Normal Curvatures

The Vertebral
Column
Primary/acommodation curves
Secondary,compensation curves
Curvatures increase
the flexibility of
spine
enable it to absorb
blows & shocks

General Structure of Vertebrae
First 2 cervical
vertebrae - atlas &
axis(Atypical)
Vertebrae C2 through L5 -
similar architecture
 body - anterior bony
block- vertebral arch.
 The vertebral arches form
the walls of the vertebral
foramen.
 central vertebral
foramen for spinal cord

General Structure of Vertebrae
◦ Transverse process
projecting out laterally
where the pedicle joins
the laminae, give
attachment to muscles
and ligaments.
◦ spinous process
projecting
posteriorly,where the two
thin plates, laminae
meet
◦ sup. and inf. articular
processes for the joining
of vertebrae

Regional variations of vertebrae
Cervical vertebrae
Vertebrae Body: small
Vertebral foramen: larger
and triangular
Spinous processes:
short and bifid in C3 to C5,
long in C6,and longer in C7
Transverse processes:
short and bifid, transverse
foramen
Articular processes:
horizontal

Regional variations of vertebrae
Thoracic / Lumbar
vertebrae
The bodies get bigger as the
vertebral column descends,
and are better able to carry
more weight.
The transverse processes of
thoracic vertebrae have
articular facets for ribs.
The thoracic spines are long
and slender and project
downward;
The lumbar spines are
massive, square and project
posteriorly.

Do You Know ?
 Giraffes and human have SEVEN
vertebrae in their necks!
13

14
Giraffes, like
humans also have
SEVEN vertebrae in
their necks!
But……….. Each is 11
inches long
Yes !

Cervical Vertebrae
(C1 – C7)
Smallest and lightest vertebrae
C3 – C7 are typical cervical vertebrae
 Body is wider laterally
 Spinous processes are short and bifid
(except C7)
 Vertebral foramina are large and triangular
 Transverse processes contain transverse
foramina
 Superior articular facets face
superoposteriorly

Atypical vertebrae
Atlas (C1)
 Lacks a body and spinous
process
 Supports the skull
 Superior articular facets
receive the occipital
condyles of skull
 Consists of anterior and
posterior arches, and two
lateral masses
 Groove for vertebral
artery
 Allows flexion and
extension of neck
Nodding the head “yes”

Atypical vertebrae
The Axis (C-2 )
 Has a body and spinous
process
 Dens (odontoid process)
projects superiorly
 Formed from fusion of the
body of the atlas with the
axis
 Acts as a pivot for rotation
of the atlas and skull
 Participates in rotating the
head from side to side

Axis (C2):
distinguished by dens which
articulates with dental
fovea of anterior arch of
atlas
Atypical vertebrae

Atypical vertebrae
Carotid tubercle: anterior
tubercle of transverse process
of C6
Vertebra prominens(C7):
contains long and non-bifid
spinous process,
visible with neck flexed,
used as clinical landmark in
counting cervical and thoracic
spinous processes

Thoracic Vertebrae (T1–T12)
All articulate with ribs
Have heart-shaped bodies from the
superior view
Each side of the body of T1 – T10 bears
demifacts for articulation with ribs
 T1 has a full facet for the first rib
 T10 – T12 only have a single facet

Thoracic Vertebrae
Vertebral Body ：
heart-shape, superior
and inferior costal fovea
Spinous processes are
long and point inferiorly
Vertebral foramen are
smaller and circular

Thoracic Vertebrae
Table 7.2b
Transverse processes
articulate with tubercles of ribs
Superior articular facets
point posteriorly
Inferior articular processes
point anteriorly
• Allows rotation and
prevents flexion and
extension

Lumbar Vertebrae (L1 – L5)
Bodies are thick and robust
Transverse processes are thin
and tapered
Spinous processes are thick,
blunt, and point posteriorly
Vertebral foramina are
triangular
Superior and inferior articular
facets directed medially
Allows flexion and extension –
rotation prevented

Lumbar vertebrae
Vertebrae Body ：
larger, kidney-shape
Vertebral foramen:
larger and triangular
Spinous processes:
project horizontally
Transverse processes:
long
Articular processes:
sagittal

Sacrum
Formed from 5 fused vertebrae
Articulates with the pelvic girdle,
laterally and forms the posterior
wall of pelvic cavity
Superioriorly, articulates with L5
Inferiorly ,articulates with coccyx
Sacral promontory
 Where the first sacral vertebra
bulges into pelvic cavity
anteriorly
Center of gravity is 1 cm
posterior to sacral promontory

Sacrum
Sacral Ala are the "wings" of the
sacrum (Fused in the adult)
Sacral hiatus is formed by failure of
lamina of S5 to fuse
Sacral cornua are two hook shaped
processes that extend down on either
side of the sacral hiatus
Sacral foramina
are for passage of the dorsal / ventral
sacral nerve rami

Transsacral (epidural) anasthesia
Cornua
palpation
Sacral
hiatus

Coccyx
Is the “tailbone”
the last part of the vertebral column
Formed from 3 – 4 fused vertebrae
Offers only slight support to pelvic organs

CERVICAL
VERTEBRA
THORACIC
VERTEBRA
LUMBAR
VERTEBRA
VERTEBRAL
BODY
rectangular body
( samall & broad
from side to side
Triangular body
(medium size
&heart shaped
Kidney-shaped
massive body
VERTEBRAL
FORMEN
large & triangular
vertebral foramen
Small circular
vertebral
foramen
Triangular
vertebral
foramina
ARTICULAR
PROCESS
SAP: backward &
upward
IAP: downward &
forward
SAP: backward &
laterally
IAP: forward &
medialy(12th
laterally)
SAP: medially
IAP: laterally
TRANSVERS
PROCESS
Transverse
foramen
Costal
facets(11T&12T
have no facet)
Mammillary and
accessory
mammillary
processes
SPINOUS
PROCESS
Small bifid
(forked) spinous
processes
Spines long and
point downward
Spines short, flat
and point
backward

Regional Vertebral Characteristics
Specific regions of the spine perform specific
functions
Types of movement that occur between
vertebrae
 Flexion and extension
 Lateral flexion
 Rotation in the long axis

Intervertebral Discs
Cushion-like pads between
vertebrae
Compose about 25% of
height of vertebral column
act as a cushion.
Prevent the vertebrae from
grinding against one another
Absorb shock during running,
jumping, and even walking.
Allow motion between the
vertebrae in bending forward,
backward, and from side to
side.

Intervertebral Discs
(Anatomy)
Nucleus pulposus
 The gelatinous inner sphere of
ntervertebral disc
 Enables spine to absorb
compressive stresses
Annulus fibrosis
 An outer collar of ligaments and
fibrocartilage
 Contains the nucleus pulposus
 Functions to bind vertebrae
together, resist tension on the
spine, and absorb compressive
forces

Bony Thorax
Forms the framework of the chest
Composed of;
◦ Thoracic vertebrae – posteriorly
◦ Ribs – laterally
◦ Sternum and costal cartilages– anteriorly
Protects thoracic organs
Supports shoulder girdle and upper
limbs
Provides attachment sites for muscles

Sternum
Formed from three sections
◦ Manubrium sterni – superior section
 Articulates with medial end of clavicles
 Jugular notch - Central indentation at superior border
of the manubrium
★ Sternal angle - A horizontal ridge where the
manubrium joins the body,
 connects 2nd costal cartilage laterally, and lies opposite
lower border of T4 posteriorly
◦ Body – bulk of sternum
 Sides are notched at articulations for costal cartilage of
ribs 2–7
◦ Xiphoid process – inferior end of sternum
 Ossifies around age 40

Sternum
Body
Costal facets
Sternal Angle
Manubrium sterni
Xiphoid process

Ribs – (12 pair)
General features
• All ribs attaced directly to
vertebral column posteriorly
Ribs 1-7 'true' ribs joined
directly to the sternum
Ribs 8-10 'false' ribs joined to
the sternum by a common
cartilage;
Ribs 11-12 'floating' ribs not
connected to the sternum at all,
connected to the diaphragm.

Characteristics of
“typical” rib
Posterior end: costal
head, costal neck, costal
tubercle,
Shaft: costal angle, costal
groove
Anterior end

Atypical rib
First rib:
tubercle for scalenus
anterior, sulcus for
subclavian artery and
vein
11th and 12th ribs
lack costal necks,
tubercles and angles

Clinical Conditions-Spine
Abnormal spinal curvatures
 Scoliosis – “twisted disease”
 abnormal lateral curvature, most common in girls
 typically results from one leg longer than the other
 Kyphosis – “hunchback”
 an exaggerated thoracic curvature
 common in elderly, 90% from osteoporosis)
 Lordosis – “swayback”
 accentuated lumbar curvature)
 temporary; individuals with ‘potbellies’ or pregnant
women

Spinal bifida: ( congenital defect )
• failure of the vertebral laminae to unite,
• nervous tissue is unprotected - paralysis

47
Stenosis of the lumbar spine ;
• A narrowing of the vertebral canal

07/31/18 48
Spondylolisthesis:
• One of the vertebrae slips forward or backward
• Lead to deformity of the spine, spinal stenosis and
nerve root compression

Herniated Intervertebral Disc
May be caused by trauma to the spine
Aging is also a contributing factor
Nucleus pulposus loses cushioning properties
Anulus fibrosus weakens
Presses the spinal cord and /or spinal nerves, causes pain.

The Axial Skeleton
Throughout Life
Aging of the axial skeleton
 Water content of the intervertebral discs
decreases
 By age 55, loss of a few centimeters in height
is common
 Thorax becomes more rigid
 Bones lose mass with age
50

Bones of Trunk (Human Anatomy)

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