Bones & its types By,M. Thiru murugan Define Bones & write its types Bones: Bone are specialized forms of strong connective tissue that forms the skeleton of the body. It is composed of calcium phosphate and calcium carbonate. It also serves as a storage area for calcium The smallest bone in the human body is called the stirrup or stapes bone, located deep inside the ear & The longest bone & strongest bone in the human is called the femur. Classification or types of bones: Bones are divided into 5 types. Long Bone Short Bone Flat Bone Irregular Bone Sesamoid Bone 1. Long Bone: A long bone is one that is cylindrical in shape, being longer than it is wide. Shape of a bone, not its size. Long bones are found in: Arms (humerus, ulna, radius) & fingers (metacarpals, phalanges) and also Legs (femur, tibia, fibula), and toes (metatarsals, phalanges). Long bones function as levers; they move when muscles contract. 2. Short bones: cube-like in shape, equal in length, width, and thickness. Example: Carpals of the wrists & Tarsals of the ankles. Short bones provide stability and support as well as some limited motion. 3. Flat Bones: The term “flat bone” is somewhat of a misnomer because, although a flat bone is typically thin, it is also often curved. Examples include the cranial bones, the scapulae, the sternum, and the ribs. Flat bones serve as points of attachment for muscles and often protect internal organs. 4. Irregular Bones: An irregular bone is one that does not have any easily characterized shape and therefore does not fit any other classification. These bones tend to have more complex shapes, like the vertebrae, Many facial bones, particularly the ones containing sinuses. 5. Sesamoid Bones: A sesamoid bone is a small, round bone that, as the name suggests, is shaped like a sesame seed. These bones form in tendons where a great deal of pressure is generated in a joint. The sesamoid bones protect tendons by helping them overcome compressive forces. Sesamoid bones vary in number and placement from person to person but are typically found in tendons associated with the feet, hands, and knees. The patellae (singular = patella) are the only sesamoid bones found in common with every person.

1. Major Joints

2. • Joint:
• A joint or articulation is the connection between
bones in the body which link the skeletal system.
• Most joints are mobile, allowing the bones to move
• Types: 3 types
1.Fibrous joint - immovable joint (synarthrosis),
2.Cartilaginous joint - slightly moveable joint
(amphiarthrosis)
3.Synovial joint - freely movable (diarthrosis )

3. 1. Fibrous joint:
• Immovable joints (synarthrosis)
• fixed & because they do not move.
• no joint cavity & via fibrous connective
tissue.
• Example: sutures of the skull
2. Cartilaginous joint:
• Slightly moveable joint
(amphiarthrosis)
• Entirely joined by cartilage (hyaline
or fibro)
• Example: intervertebral joints

4. 3. Synovial joint:
• Freely movable joints (diarthrosis)
• Bones separated by synovial cavity
• Presence of a fluid-filled joint cavity
• Most common type
The 3 main features:
i. Articular capsule,
ii. Articular cartilage,
iii.Synovial fluid.

5. i) Articular capsule: It surrounds the joint and is continuous
with the Periosteum
• It consists of 2 layers:
Fibrous layer (outer): It holds together the connecting
bones
Synovial layer (inner): It absorbs and secretes synovial
fluid, and is responsible for the nutrient exchange between
blood and joint. Also known as the synovium.
ii) Articular Cartilage:
• The articulating surfaces - hyaline cartilage.
• 2 main roles: minimizing friction & absorbing shock.

6. iii) Synovial Fluid:
• The synovial fluid is located
within the joint cavity of a
synovial joint.
• It has 3 primary functions:
1. Lubrication,
2. Nutrient distribution
3. Shock absorption.

7. Types of synovial joints:
a) Pivot joint
b)Hinge joints
c) Saddle joint
d)Plane joints
e) Condyloid joint
f) The ball & socket
joint

8. • A) Pivot joint:
• Pivot joint, also called rotary
joint, or trochoid joint, that
allows only rotary movement
around a single axis.
• Ex:
• Joint between the atlas and the
axis (first and second cervical
vertebrae),
• Movement of the bones of the
forearm (radius and ulna)
against the upper arm,

9. B) Hinge joints:
• It serves to allow motion
primarily in one plane.
• The hinge joints of the
body include the elbow,
knee, interphalangeal
(IP) joints of the hand
and foot and the
tibiotalar (ankle) joint of
the ankle.

10. C) Saddle joint:
• The saddle joint gets its name
because the bone forming one part
of the joint is concave (turned
inward) at one end and looks like a
saddle.
• The other bone’s end is convex
(turned outward), and looks like a
rider in a saddle.
• These highly flexible joints are
found in various places in the body,
including the thumb and inner ear.

11. D) Plane joints:
Plane joint, also called gliding
joint or arthrodial joint,
• The surfaces of the bones are
flat or nearly flat, enabling the
bones to slide over each other.
• Examples - intercarpal &
intertarsal joint

12. E) Condyloid joint:
• Composed of an egg-shaped
bone known as a condyle
that fits into a similarly
shaped cavity.
• Only allow for forward-
backward and side to side
movement and do not allow
rotation.
• Example: wrist.

13. F) The ball-and-socket joint:
• One bone with a rounded head
that fits into the cup of another
bone.
• Since the rounded head can move
freely within the cup, or socket,
this allows for movement in all
directions.
• Common ball and socket joints
include the hips and shoulders.

14. • Major joints and structure:
• Shoulder joint (Glenohumeral joint)
• Ball and socket joint between the scapula and the humerus.
• Major joint connecting the upper limb to the trunk & most mobile
joints
• Articulating Surfaces
• Head of the humerus with the glenoid cavity (or fossa) of the
scapula.
• Covered with hyaline cartilage. The head of the humerus is much
larger than the glenoid fossa, giving the joint a wide range of
movement
• To reduce the disproportion in surfaces, the glenoid fossa is deepened
by a fibro cartilage rim, called the glenoid labrum.

16. • Joint Capsule and Bursae:
• The joint capsule is a encloses the structures of the joint.
It extends from the anatomical neck of the humerus to
‘rim’ of the glenoid fossa. The joint capsule permitting
greater mobility (particularly abduction).
• The synovial membrane produces synovial fluid to
reduce friction between the articular surfaces.
• Several synovial bursae are present. A bursa is a
synovial fluid filled sac, which acts as a cushion between
tendons and other joint structures.

17. • The bursae that are important clinically are:
• Subacromial bursa: located deep to the deltoid and
acromion, and superficial to the supraspinatus
tendon and joint capsule.
• Subscapular bursa: located between the
subscapularis tendon and the scapula.
• Subcoracoid bursa: It is located anterior to the
subscapularis muscle and inferior to the coracoid
process.

19. • Ligaments: key role in stabilizing the bony structures.
1. Glenohumeral ligaments (superior, middle and
inferior)
2. Coracohumeral ligament
3. Transverse humeral ligament
4. Coraco–clavicular ligament composed of trapezoid &
conoid ligaments
• The other major ligament is the (6) coracoacromial
ligament.

20. 1
2
3
4
5
6

21. • Muscles Acting on
Shoulder Joint:
• Above - Supraspinatus
• Below - Long head of
Triceps
• Front - Subscapularis
• Behind - Infraspinatus
and Teres Minor
• Deltoid muscle.

23. • Movements: As a ball and socket synovial joint - wide
range of movement permitted: Extension
• Flexion
• Abduction
• Adduction
• Blood Supply: Anterior circumflex humeral vessels,
Posterior circumflex humeral vessels, Suprascapular
vessels
• Nerve supply: Axillary nerve, Musculocutaneous
nerve, Suprascapular Nerve & Lateral pectoral nerve
•Internal rotation.
•External rotation
•Circumduction

24. • Hip joint:
• Largest weight-bearing joint
• Ball & socket joint
• The thighbone or femur and the
pelvis join to form the hip joint.
• The hip joint is made up of the
following:
1. Bones and joints
2. Ligaments of the joint capsule
3. Muscles and tendons
4. Nerves and blood vessels

25. 1. Bones and Joints of the Hip:
• It is comprised of 2 bones: the thighbone or
femur, and the pelvis (ilium, ischium & pubis)
• The ball of the hip joint - femoral head while the
socket is formed by the acetabulum
• fibrocartilaginous Labrum is attached to the
acetabulum and further increases the depth of the
socket.
• Synovial fluid

26. 2. Ligaments of the Hip Joint:
• Iliofemoral ligament
• Pubofemoral ligament
• Ischiofemoral ligament
• Ligamentum teres: femoral head to the
acetabulum.
• Acetabular labrum: lines the acetabular socket.

28. 3. Muscles and Tendons of the Hip Joint: A long tendon called
the iliotibial band runs along the femur from the hip to the
knee
• Gluteal: (gluteus minimus, gluteus maximus, and gluteus
medius)
• Adductors: These muscles are in the thighs which help in
adduction
• Iliopsoas: * front of the hip joint and provides flexion.
• Rectus femoris: front of the thigh. They are also called hip
flexors.
• Hamstring muscles: bottom of the pelvis and run down the
back of the thigh. they help in extension

29. • Hip Movements:
• All the anatomical parts of the hip work together to enable
various movements.
• Hip movements include
• Flexion
• Extension
• Abduction
• Adduction
• Circumduction
• Hip rotation.

30. 4. Nerves and Arteries of the Hip Joint
• femoral nerve in the front of the femur and the
sciatic nerve at the back.
• The hip is also supplied by a smaller nerve known
as the obturator nerve.
• The femoral artery, one of the largest arteries in
the body, arises deep in the pelvis and can be felt
in front of the upper thigh.

31. • Knee joint: hinge type synovial joint, which mainly allows for
flexion and extension It is formed by patella, femur and tibia.

32. • Articulating Surfaces
• two articulations: tibiofemoral
& patellofemoral.
• lined with hyaline cartilage
• Tibiofemoral: medial & lateral
condyles of the femur articulate
with the tibial condyles.
• Patellofemoral: anterior aspect
of the distal femur articulates
with the patella..

33. • Menisci: A meniscus is a piece of cartilage found where two bones
meet (joint space). It protect and cushion the joint surface and bone
ends.
• The medial and lateral menisci are fibro cartilage, serve two
functions:
1. Increasing stability of the joint.
2. To act as shock absorbers
• They are C shaped and attached at both ends to the intercondylar area
of the tibia.
• In addition to the intercondylar attachment, the medial meniscus is
fixed to the tibial collateral ligament and the joint capsule. The lateral
meniscus is smaller and does not have any extra attachments,
rendering it fairly mobile

35. • Bursae: A bursa is synovial fluid filled sac, found between moving
structures in a joint – with the aim of reducing wear and tear on
those structures. There are 4 bursae found in the knee joint:
• Suprapatellar bursa: an extension of the synovial cavity of the
knee, located between the quadriceps femoris and the femur.
• Prepatellar bursa: found between the apex of the patella and the
skin.
• Infrapatellar bursa: split into deep and superficial. The deep bursa
lies between the tibia and the patella ligament. The superficial lies
between the patella ligament and the skin.
• Semimembranosus bursa: located Posteriorly in the knee joint,
between the semimembranosus muscle & the medial head of the
gastrocnemius

37. • Ligaments: The major ligaments in the knee joint are:
• Patellar ligament: a continuation of the quadriceps femoris tendon
distal to the patella. It attaches to the tibial tuberosity.
• Collateral ligaments: two strap-like ligaments. They act to stabilize the
hinge motion of the knee, preventing excessive medial or lateral
movement
1. Tibial (medial) collateral ligament: wide and flat ligament, found on
the medial side of the joint. Proximally, it attaches to the medial
epicondyle of the femur, distally it attaches to the medial condyle of the
tibia.
2. Fibular (lateral) collateral ligament: thinner and rounder than the
tibial collateral, this attaches proximally to the lateral epicondyle of the
femur, distally it attaches to a depression on the lateral surface of the
fibular head.

38. • Cruciates Ligaments: these two ligaments connect the femur
and the tibia. In doing so, they cross each other, hence the term
‘cruciate’ (Latin for like a cross)
1. Anterior cruciate ligament: attaches at the anterior
intercondylar region of the tibia where it blends with the
medial meniscus. It ascends posteriorly to attach to the femur
in the intercondylar fossa. It prevents anterior dislocation of
the tibia onto the femur.
2. Posterior cruciate ligament: attaches at the posterior
intercondylar region of the tibia and ascends anteriorly to
attach to the anteromedial femoral condyle. It prevents
posterior dislocation of the tibia onto the femur.

40. • Movements: There are four main movements that the knee joint
permits:
• Extension
• Flexion
• Lateral rotation
• Medial rotation
• Lateral and medial rotation can only occur when the knee is flexed
(if the knee is not flexed, the medial/lateral rotation occurs at the
hip joint).
• Neurovascular Supply: The blood supply: through the genicular
anastomoses around the knee, which are supplied by the genicular
branches of the femoral & popliteal arteries.
• The nerve supply: femoral, tibial and common fibular nerves.