9. skeletal system-1.pptx

Skeletal System
 Skeleton means dried up body
 Skeletal system is composed of bone, cartilage, joints and
ligaments.
 Each individual bone is an organ.
7/2/2023 skeletalsystem by:- Zufan T.(Msc) 1

Functions of Bone
 Support –provides hard framework that supports the weight of
the body.
 protection
 Movement
 Blood cell formation
 Storage of minerals- calcium and phosphate
 Serve as attachment for muscles

Skeletal System:
• has two main parts:
1. Axial skeleton
• consists of the bones of the :-
– head (cranium),
– vertebrae bones
– ribs and sternum
– Hyoid bone
2. Appendicular skeleton
• consists of the bones of the:-
– limbs, including those forming the pectoral (shoulder) and
pelvic girdles.

Region of Skeleton
Axial skeleton: Number of Bones
Appendicular skeleton:
Skull Shoulder girdles Pelvic girdle
Cranium 8 Clavicle 2 Hip bone 2
Face 14 Scapula 2
Auditory Ossicles 6 Upper extremities Lower extremities
Hyoid 1 Humerus 2 Femur 2
Vertebrae 26 Patella 2
Sternum 1 Radius 2 Tibia 2
Ribs 24 = 80 Ulna 2 Fibula 2
Carpals 16 Tarsals 14
Metacarpals 10 Metatarsals 10
Phalanges 28 Phalanges 28
64 62
206

Cartilage
• A resilient, semirigid, avascular form of connective
tissue.
• forms parts of the skeleton where more flexibility is
necessary.
– e.g., the costal cartilages that attach the ribs to the sternum.
• Periosteum :-
– Fibrous connective tissue covering that surrounds bone.
• Perichondrium :-
– The fibrous connective tissue covering that
surrounds cartilage; excluding articular cartilage.

Bones:
wo types:
Compact and
Spongy (trabecular or cancellous).
ey differ based on :-
The relative amount of solid matter and
The number and size of the spaces they contain.

Transeverse sections of Femur
• All bones have a :-
– Superficial thin layer of
compact bone around a
central mass of spongy
bone.
• The spongy bone is
replaced by a medullary
(marrow) cavity.
• Within this cavity of
adult bones, and between
the spicules of spongy
bone blood cells are
formed.

Classification of Bones
Bones are classified according to their length.
• Long bones :-
– Tubular structures.
• e.g., humerus in the arm; phalanges in the fingers.
• Short bones :-
– Cuboidal
– Found only in the ankle (tarsus) and wrist (carpus).

Classification of Bones
According to their shape
• Flat bones :-
– usually serve as protective functions
e.g., those of the cranium protect the brain.
• Irregular bones:-
– Bones of face, have various shapes other than long, short, or
flat.
• Sesamoid bones:-
– Develop in certain tendons.
– These bones protect the tendons from excessive wear and
– Often change the angle of the tendons as they pass to their
attachments.
• e.g., patella, or knee cap

The Axial skeleton
The skull
• Contain 22 bones.
• Rests on the
superior of vertebral
column.
• It is composed of
cranial bones
(neurocranium)
and facial bones
(viscerocranium).

Neurocranium
• In adults formed by series
of 8 bones
• 4 singular bones centered
on midline
– Frontal,
– Ethmoidal,
– Sphenoidal, And
– Occipital
• 2 bilateral pairs
– Temporal
– Parietal
• Roof, the Calvaria
(skullcap)- flat bones
• F P O, united by
Sutures
• Floor or Cranial Base
(basicranium)-
irregular bones
 Sphenoidal
 Temporal
 Ethmoid bone

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7/2/2023 skeletalsystem by:- Zufan T.(Msc)

Viscerocranium (Facial skeleton)
• Forms the anterior part of the cranium
• 14 irregular bones
• 2 single
– Mandible &
– vomer
• 6 bones, as bilateral pairs
– Maxillae;
– Inferior nasal conchae
– Zygomatic,
– Palatine,
– Nasal, and
– Lacrimal bones

The vertebral column
• Together with the sternum & ribs constitutes the skeleton
of the trunk of the body.
• Adult : contains 26 vertebras.
• Prior to fusion of sacral & coccygeal vertebrae the total
number is 33.
• Function
– Encloses & protect spinal cord,
– supports the head
– Serves as a point of attachment for the ribs & muscles
of the back.
• Inter vertebral discs
– Joint Between adjacent vertebrae

The vertebral column…

Typical vertebra
• Consist of: body, vertebral arch and 7 processes.
1. The body (Centrum): thick, disc shaped, anterior part.
– Has superior and inferior roughened area for attachment
with IV discs.
2. The vertebral (neural) arch: extends posterior from the body
of the vertebrae.
- With the body it surrounds the spinal cord

Typical vertebra…
20

Typical vertebra …
Vertebral (spinal) canal
• Formed by foramina of all vertebras together.
Intervertebral foramen
• Formed by notch of pedicles superiorly & inferiorly
• Serves as passage of nerves that come out of spinal cord
Processes
1. Transverse processes : on both side extends laterally.
2. Spinous processes : extends posteriorly & inferiorly from the
junction of the laminae.
– Both the transverse & spinous processes are muscle attachments.
3. four articular processes form joints with other vertebra

Ribs
• Curved, flat bones that form most of the thoracic cage,
• They are remarkably light in weight yet highly resilient.
• Three types of ribs:
1. True (vertebrocostal) ribs (1st- 7th ribs)
• attach directly to the sternum through their own costal cartilages.
2. False (vertebrochondral) ribs (8th -10th ) ribs)
• have cartilages that are joined to the rib just superior to them.
3. Floating (free) ribs (11th- 12th ribs)
• have rudimentary cartilages that do not connect even indirectly with
the sternum.

Ribs…
.

Ribs…

Sternum
• The flat, vertically elongated
bone.
• Forms the middle of the
anterior part of the thoracic
cage.
• The sternum consists of three
parts: manubrium, body,
and xiphoid process

Sternum

The Appendicular skeleton
pectoral girdle
• Consists of the scapulae (left and right) and the clavicles (left
and right) bones
THE CLAVICLE (COLLAR BONE)
• It connects the upper limb to the trunk.
• Medial end: enlarged and triangular.
• Articulates with the manubrium at sternoclavicular (SC)
joint.
• It transmits forces from the upper limb to the axial skeleton.
• Lateral end:
– is flat and articulates with the acromion of scapula at the
Acromioclavicular (AC) joint.

THE CLAVICLE…

Scapula (Shoulder Blade)
• It has 3 borders
Medial (vertebral) border,
Lateral (axillary) border &
Superior border.
• Acromion: lateral end of spine
– flat expanded part that articulate with the clavicle.

Scapula
30

7/2/2023 31
skeletalsystem by:- Zufan T.(Msc)

Scapula….
• Glenoid cavity or fossa –
receives and articulates
with the head of the
humerus at the
glenohumeral jont.
• A shallow, concave, oval
fossa

BONE OF THE ARM
HUMERUS
Provide skeletal
support for the arm.
Articulate with
scapula above
Parts
- Head
- Surgical & anatomical
necks,
- Greater and lesser
tubercles.

7/2/2023 34
skeletalsystem by:- Zufan T.(Msc)

Arm bones..
 Anatomical neck of the humerus
 separating head from the greater and lesser tubercles.
 Surgical neck of the humerus,
 a common site of fracture,
 The narrow part distal to the head and tubercles.
 Greater tubercle
 At the lateral margin of the humerus,
 The lesser tubercle projects anteriorly from the bone.
 Bicipital groove - groove between tubercle

Humerus…
Inferior end
– widens as the sharp medial and lateral supraepicondylar ridges
form.
– End distally in medial epicondyle and the lateral epicondyle.
Articular surface
– Trochlea
Articular surface for ulna
– Capitulum -
Articulate with radius
- Olecranon fossa :
– The largest of the fossa,
– Superior to the trochlea on the posterior surface.
– Accommodates the olecranon of the ulna during full extension of the
elbow

Bones of Forearm
1. ULNA
• The medial and longer of the two forearm bones.
• Articulate with the humerus proximally and the head of the
radius laterally.
• Has two prominent projections:
(1) The olecranon: projects proximally from its posterior aspect.
(2) The coronoid process : which projects anteriorly.
• Both form the walls of the trochlear notch
• The ulna does not reach and therefore does not participate in
the wrist (radiocarpal) joint.

Bones of Forearm…

RADIUS
• The lateral and shorter of the two forearm bones.
• proximal end has
– short head,
– neck,
– medially directed tuberosity.
• Head
– Discoid and concave.
– Articulate with the capitulum of the humerus.
– It also articulates peripherally with the radial notch of the ulna.
• The neck :
– A constriction distal to the head.

RADIUS…
The shaft
• In contrast to the ulna, gradually enlarges as it passes distally.
• Its lateral aspect becomes increasingly ridge-like, terminating
distally in the radial styloid process.
• Radial styloid process:
– larger than the ulnar styloid process
– extends farther distally.

Bones of Hand
Carpal bones
 Are eight in number
 arranged in two rows.
1. Proximal row:
• From the radial to the ulnar side are :
– Scaphoid,
– Lunate,
– Triquetrum,
– Pisiform;
2. Distal row: in the same order are :
– Trapezium
– Trapezoid,
– Capitate,
– Hamate.

Bones of Hand…

Metacarpus
– Forms the skeleton of the palm of the hand between the
carpus and the phalanges.
– composed of five metacarpal bones (metacarpals).
– Each consists of a :
• Base,: articulate with the carpal bones,
• Shaft,
• Head : articulate with the proximal phalanges .
• Phalanges
– Each digit has three except for the first (the thumb), which
has only two.
– Each has a base proximally, a shaft (body), and a head
distally.

BONES OF LOWER LIMB
• Divided into two functional components:
– Pelvic girdle and
– Bones of the free lower limb.
• The pelvic girdle (bony pelvis) :
– A bony ring composed of:
– Sacrum and right and left hip bones joined anteriorly at the
pubic symphysis.
– Attaches the free lower limb to the axial skeleton.

The pelvic girdle…

HIP BONE
• Each mature hip bone is formed by the fusion of three primary
bones:
• Ilium,
• Ischium, and
• Pubis.
• At puberty, these bones are still separated by a triradiate
cartilage centered in the acetabulum.
• The cartilage disappears and the bones begin to fuse at 17
years of age
Ilium
• Forms the largest part of the hip bone
• Contributes the superior part of the acetabulum.

Fig. 2: Parts of hip bone of 13 years old showing the triradiate cartilage.

HIP BONE…

HIP BONE…
• Iliac tubercle : a prominence on the external lip of the crest.
– lies 5-6 cm posterior to the ASIS.
• Iliac fossa
– On medial aspect of each ala.
– Is a large, smooth depression.
– provides proximal attachment for the iliacus muscle.

ISCHIUM
• Forms the posteroinferior part of the hip bone.
• Ischiopubic ramus
– formed by union of ramus of ischium with the inferior ramus of
the pubis.
• Constitutes the inferomedial boundary of the obturator foramen.
• Body's weight rests on it when sitting.
PUBIS
• Forms the anteromedial part of the hip bone.
• Contribute to the anterior part of the acetabulum,

ACETABULUM
• The large cup shaped cavity or socket on the lateral aspect of the hip
bone.
• Articulates with the head of the femur to form the hip joint.

The Femur
• The longest and heaviest bone in the body.
• It transmits body weight from the hip bone to the tibia when a
person is standing
• Its length is approximately ¼ the person's height.
• Consists of :
– A shaft (body) and
– two ends, superior or proximal and inferior or distal

The Femur…
Head of the Femur
• Smooth and forms about two-thirds of a sphere.
• Directed superomedially, slightly anteriorly to fit into the
acetabulum of the hipbone.
The Neck of the Femur
 It connects the head to body.
 It runs obliquely in an inferolateral direction.
 Limited laterally by the greater trochanter and is narrowest in
diameter at its middle

The Femur…
Trochanters
• Are blunt elevations where the neck joins the femoral
shaft.
Greater Trochanter
• A large, laterally placed.
• Projects superiorly and posteriorly.
• Can be easily palpated on the lateral side of the thigh.
• Provide attachment for abductors and rotators of the
thigh.

The Femur…
• The Body (shaft) of the Femur
• It is slightly bowed (convex) anteriorly and is
narrowest at its midpoint.
The Condyles of the Femur
 Make up nearly the entire distal end.
 Articulate with menisci (crescentic plates of
cartilage) and tibial condyles to form the knee
joint

Tibia and Fibula
TIBIA
• Articulates with the condyles of the femur superiorly and the
talus inferiorly.
• Located on the anteromedial side of the leg, nearly parallel to
the fibula
• The second largest bone in the body
• Superior (proximal) end :
– widens to form medial and lateral condyles
• Shaft : is truly vertical within the leg
– having three surfaces and borders: medial, lateral/
interosseous, and posterior.

Tibia...
• Tibial tuberosity
– At the superior end of the anterior border,
– a broad provides distal attachment for the patellar ligament.
FIBULA
• Lies posterolateral to the tibia and is firmly attached to it by
the tibiofibular syndesmosis.
• Has no function in weight-bearing. It serves mainly for muscle
attachment

Tibia and Fibula

FOOT
• Skeleton of the foot consists of :
– 7 tarsals, 5 metatarsals, and 14 phalanges .
• The hindfoot: talus and calcaneus.
• The midfoot: navicular, cuboid, and cuneiforms.
• The forefoot: metatarsals and phalanges.
• TARSUS
• Consists of seven bones :
– Talus, calcaneus, cuboid, navicular, and three cuneiforms.
– Only one bone, the talus, articulates with the leg bones.

METATARSUS
• Consists of five metatarsals
• Numbered from the medial side of the foot.
• Each has a base proximally, a shaft, and a head distally.
• 1st metatarsal : is shorter and stouter than the others.
– on it’s base has large tuberosity.
– On it’s plantar surface of the head are prominent medial
and lateral sesamoid bones
• 2nd metatarsal : is the longest.
• 5th metatarsal
– It’s tuberosity projects laterally over the cuboid.

Joints:
• A joint is an articulation, or the place of union or junction
between two or more rigid components.
• Classification of Joints:
• Three types of joints :-
– Classified according to the manner or type of material by
which the articulating bones are united.
• Fibrous,
• Cartilaginous, and
• Synovial)

Joints…
• Fibrous joints:
• United by fibrous tissue (sutures of the vault of the skull).
• A gomphosis (dentoalveolar syndesmosis) :-
– A type of fibrous joint in which a peg-like fibrous process
stabilizes a tooth.

Joints…
• Cartilaginous joints:
• United by hyaline cartilage or fibrocartilage.
• Primary cartilaginous joints (synchondroses) :-
– United by hyaline cartilage.
– Permit growth of the length of the bone and
– Allow slight bending during early life, until the epiphysial plate
converts to bone and the epiphyses fuse with the diaphysis.
• Secondary cartilaginous joints (symphyses):-
– Strong, slightly mobile joints, united by fibrocartilage.
Ex- Intervertebral disc.

Joints…
• Synovial joints:
• The articular cavity of synovial joints is a potential space that
contains a small amount of synovial fluid.
• Synovial fluid serves the dual function of nourishing the
articular cartilage and lubricating the joint surfaces.
• Usually reinforced by accessory ligaments.
NB - ligament is connective tissue that connects bone with
bone

Types of synovial joints
1, Plane joints: permit gliding or sliding movements
ex:- acromioclavicular joint
2, Hinge joints:- permit flexion and extension Ex:- elbow joint
3, Saddle joints:- permit abduction and adduction as well as flexion
and extension. ex:- carpometacarpal joint
4, Condyloid joints:- similar with saddle is but axis more free to
move.
Ex:- metacarpophalangail joints
5, Ball and socket joints:- allow flexion and extension, abduction
and adduction, medial and lateral rotation
Ex:- shoulder joint
6, Pivot joints:- permit rotation around a central axis
ex:- atlantoaxial joint
69

70

Common joints in our body
Joints of the Upper Limb
THE SHOULDER JOINT
• a ball and socket joint of the
synovial variety.
• most frequently dislocated
because of
 most mobile of all joints;
 shallow glenoid cavity
 cavity accepts about one-third
of large convex head of
humerus
 A lax capsule; lax capsular
ligament.
 Inferior or antero-inferiorly
deficient:-most common site
of dislocation:
77

Shoulder dislocation
• Is commonly dislocated by direct or indirect injury due to its
freedom of movement.
• 45% of all major joint dislocation in the body.
• Anterior/inferior dislocation: 95% to 97%
• Posterior/superior dislocation: 2 to 5%

Cont…

Elbow Joint:
• Consists of lower end of humerus & upper ends of
radius & ulna.
• Trochlear notch of ulna grasp the trochlea.
• Head of radius moves on capitulum.
• Movements at this joint are solely flexion & extension
(hinge like).
• Capsule surrounding elbow joint & superior radio-ulnar
joint is strengthened by medial & lateral ligaments of
Elbow J.
80

Movement of elbow joint and superior radioulnar joints

82

Nursemaid's elbow or pulled elbow
• Subluxation and
dislocation of the head
of the radius
• Caused by sudden lift
of child (jerked) by the
upper limb while the
forearm is pronated
(e.g., lifting a child into
a bus)

Wrist Joint, or Radio-Carpal Joint:
 B/n radius & a disc of fibrocartilage (which excludes
ulna from wrist joint) on one side & 3 carpal bones on the
other side (scaphoid, lunate & triquetrum).
 Collateral ligaments( ulnar and radial) strengthen this
joint.
 Movements at the wrist joint include: flexion &
extension, as well as adduction & abduction (ulnar &
radial deviation).
84

85

87
Hip joint
• The largest joint in the body
• Ball-and-socket synovial joint
• Forms connection between lower limb and pelvic girdle
• Articular surfaces
– head of femur
– Acetabulum of hip bone
Movements of the hip joint
– Flexion, Extension
– Abduction, Adduction
– Medial and lateral rotation

88

89
• The hip is usually
dislocated backwards
• posterior dislocation is
produced by a force
applied along the
femoral shaft with the
hip in the flexed and
adducted position,
• If the hip is abducted,
dislocation must be
accompanied by a
fracture of the
posterior acetabular
lip
Dislocation of the hip joint

90
Knee joint
• Articulations
– 2 femorotibial articulations (lateral and medial)
• Between femoral and tibial condyles
– 1 intermediate femoropatellar articulation
• Between patella and the patellar surface of the femur
• Movements of the knee
– flexion and extension

91
Ligaments that
support knee joint
• Collateral ligaments
- Tibial (medial) collateral
ligament:
- Fibular (lateral) collateral
ligament
• Cruciate ligament
- anterior cruciate ligament:
- posterior cruciate
ligament:
• Patellar ligament
• oblique popliteal
ligament

93
Ankle (talocrural) joint
• Articular surfaces
– lower end of the tibia and fibula forms malleolar socket
– trochlea of talus
• The weight of the body is transmitted to the talus by the
tibia
Movements of the ankle
– Plantar and dorsiflexion

94

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