lec5 anatomy

Anatomy Dr.Israa H. Mohsen
Lecture 5
The vertebral column
The vertebral column—a flexible structure consisting of 33 vertebrae—holds the head
and torso upright, serves as an attachment point for the legs, and encases the spinal
cord. Its unique structure allows the body to bend forward, backward, and sideways.
Vertebrae Characteristics
An opening called the
vertebral foramen
allows for passage of
the spinal cord.
The body is the
weight-bearing
portion of the
vertebra.
A spinous
process projects
posteriorly
from the vertebra.
Transverse
processes extend
from each side of the
vertebra. Both the
transverse and
spinous processes
serve as attachment
points for muscles and
ligaments.
Intervertebral Disc
In between each vertebra is an intervertebral disc. Designed to support weight and
absorb shock, the intervertebral disc consists of two parts:
The Thoracic Cage
The thoracic cage consists of the thoracic vertebrae, the sternum, and the ribs. These
bones form a cone-shaped cage that surrounds and protects the heart and lungs and
provides an attachment point for the pectoral girdle (shoulder) and upper limbs.
Expansion and contraction of the thoracic cage causes the pressure changes in the
lungs that allow breathing to occur.
Sternum
has three regions
1. Manubrium:
2. Body: This is the
longest portion.
3.Xiphoid process:
provides an
attachment point
for some abdominal
muscles.
Ribs
Twelve pairs of
ribs attach to the
vertebral column.
Ribs 1 to 7,
called true ribs,
attach to the
sternum by a
strip of hyaline
cartilage called
costal cartilage.
Ribs 8, 9, and 10
attach to the cartilage
of rib 7; these ribs, as
well as ribs 11 and 12,
are called false ribs.
Ribs 11 and 12, called
floating ribs, do not
attach to any part of the
The lower edges of the thoracic cage are called anterior thoracic cage.
the costal margins.
Pectoral Girdle
Also called the shoulder girdle, the pectoral girdle supports the arm. The two
pectoral girdles—one on each side of the body—consist of a clavicle (collarbone) and
a scapula (shoulder blade).
Upper Limb
The upper limb, or arm, consists of the humerus (upper arm bone), the radius and the
ulna (the bones of the lower arm), and the carpals (the bones of the hand).
the scapula lies over ribs 2 to 7.
The lateral portion of this triangleshaped
bone has three main features.
• The acromion process: This
extension of the scapula
articulates with the clavicle; it is
the only point where the arm and
the scapula attach to the rest of
the skeleton.
• The coracoid process: This
finger-like process provides a
point
of attachment for some of the
muscles of the arm.
• The glenoid cavity: This
shallow socket articulates with the
head of the humerus (upper arm
bone).
A slightly S-shaped
bone, the clavicle
articulates with the
sternum and the
scapula and helps
support the shoulder.
the radius, is located on
the same side as the
thumb.
• The proximal head of
the radius is a distinctive
disc that rotates on the
humerus when the palm
is turned forward and
back.
• The radial tuberosity
is where the biceps
muscle attaches to
the bone
The ulna is the other bone of the
lower arm; it is longer than the
radius
The styloid processes of the
radius and ulna are the bony
bumps that can be felt at the
wrist.
The humerus is the
long bone of the upper
arm. It contains
• Head:
; it articulates with the
glenoid cavity of the
scapula.
• Olecranon fossa:
This is a depression on
the posterior side of the
humerus.
• Olecranon process:
it slides in the olecranon
fossa when the arm is
extended.
Hand
The hand consists of the wrist, palm, and fingers.
Pelvic Girdle
Each of the two large bones of the hip is called an os coxae; it may also be called a
coxal bone or innominate bone. Together they form what’s known as the pelvic
girdle: the foundation of the pelvis. The os coxae is not a single bone; rather, it
consists of three bones fused together.
The combination of the os coxae and the sacrum is known as the pelvis. The pelvis
supports the trunk, provides an attachment point for the legs, and also protects the
organs of the pelvis (including the lower colon, reproductive organs, and urinary
bladder).
The fingers are formed
by bones called
phalanges.
(The singular form of
phalanges is phalanx.)
The thumb contains two
phalanges; the rest of
the fingers contain three.
Five metacarpal bones
form the palm of the hand.
The proximal end is called
the base, the shaft is
called the body, and the
distal end is called the
head.
Eight carpal bones—
arranged in two rows
of four bones—form
the wrist. These bones
allow the wrist to move
back and forth as well
as side to side.
The male and female pelvises have a number of differences, mainly because the
female pelvis is adapted for pregnancy and childbirth.
Lower Limb
The bones of the lower limb—which consist of the femur (thigh bone), patella
(kneecap), tibia and fibula (bones of the lower leg), and foot—join with the pelvis to
give the body a stable base. More importantly, the bones of the lower limb are
articulated in such a way as to allow the body to move.
Femur
The longest and strongest bone in the body, the femur articulates with the acetabulum
of the pelvis to form a ball-and-socket joint.
The head of the femur fits
into the rounded contour of
the acetabulum.
These two bony projections
provide attachment points
for hip muscles.
The medial and lateral
epicondyle are the widest
points of the femur at the
knee.
The neck of the femur is a
frequent site for fractures in
elderly persons.
Commonly known as the kneecap, the
patella is a triangular sesamoid bone
embedded in the tendon of the knee.
At birth, the patella is composed of
cartilage. It ossifies between the ages
of three and six years.
Foot and Ankle
The bones of the foot and ankle are arranged similarly to those of the hand. However,
because the foot and ankle bear the weight of the body, the size of the bones, as well
as how they’re arranged, differs.
Fibula
The long and slender fibula resides
alongside the tibia and helps stabilize
the ankle.
It does not bear any weight.
Tibia
Of the two bones in the lower
leg, the tibia is the only one
that bears weight.
Commonly called the
shinbone, the tibia articulates
with the femur.
The phalanges form the toes.
The great toe, called the
hallux, contains only two
bones: a proximal and distal
phalanx. The remaining toes
contain a proximal, middle,
and distal phalanx.
The metatarsals—which are
numbered I through V,
beginning medially—form
the middle portion of the foot.
The tarsal bones comprise
the ankle.
The distal row of tarsal
bones consists of three
cuneiforms and the large
cuboid.
The second-largest tarsal
bone is the talus.
The talus articulates with
three bones: the calcaneus
on its inferior surface, the
tibia on its superior surface,
and another tarsal bone
(called the navicular) on its
anterior surface.
The largest tarsal bone is
the calcaneus.
This bone, which forms the
heel, bears much of the
body’s weight
Navicular
Arches of the Foot
Strong ligaments hold the foot bones together in a way that forms arches in the foot. Just as arches add supporting strength to a building, foot arches give the foot more strength to support the weight of the body.