skeletal system
DESCRIPTION
SKELETAL SYSTEM. Prepared by Dr.Vindya Rajakaruna M.B.B.S. (COLOMBO) Done by Dr.Ishara Maduka M.B.B.S. (COLOMBO). Composed of the body’s bones and associated ligaments, tendons, and cartilages. There are 206 named bones in the human body. Functions:. Support - PowerPoint PPT PresentationTRANSCRIPT
SKELETAL SYSTEM
Prepared by
Dr.Vindya Rajakaruna M.B.B.S. (COLOMBO)
Done by
Dr.Ishara Maduka M.B.B.S.(COLOMBO)
• Composed of the body’s bones and associated ligaments, tendons, and cartilages.
• There are 206 named bones in the human body.
Functions:1. Support
• The bones of the legs, pelvic girdle, and vertebral column support the weight of the erect body.
• The mandible (jawbone) supports the teeth.
• Other bones support various organs and tissues.
2.Protection • The bones of the skull protect the brain.• Ribs and sternum (breastbone) protect
the lungs and heart.• Vertebrae protect the spinal cord
3. Movement • Skeletal muscles use the bones as levers
to move the body.
3. Reservoir for minerals and adipose tissue• 99% of the body’s calcium is stored in
bone.• 85% of the body’s phosphorous is stored
in bone.• Adipose tissue is found in the marrow of
certain bones4. Hematopoiesis
• Blood cell formation.• All blood cells are made in the marrow of
certain bones
Bone Classification
Axial skeleton• Forms long axis of the body.• Includes the bones of the skull,
vertebral column, and rib cage.• These bones are involved in
protection, support, and carrying other body parts.
Appendicular skeleton• Bones of upper & lower limbs and the
girdles (shoulder bones and hip bones) that attach them to the axial skeleton.
• Involved in locomotion and manipulation of the environment.
Bone Classification
1. Long Bones • Much longer than they are wide.• All bones of the limbs except for the
patella (kneecap), and the bones of the wrist and ankle.
• Consists of a shaft plus 2 expanded ends.• Your finger bones are long bones even
though they’re very short
2. Short Bones• Roughly cube shaped.• Bones of the wrist and the ankle.
3. Flat Bones• Thin, flattened, and usually a bit curved.• Scapulae, sternum, (shoulder blades),
ribs and most bones of the skull.
Sternum
4. Irregular Bones• Have weird shapes that fit none of the 3
previous classes.• Vertebrae, hip bones, 2 skull bones
( sphenoid and the ethmoid bones).
Sphenoid Bone
Bone Structure• Bones are organs. • Thus, they’re composed of multiple tissue
types. Bones are composed of:– Bone tissue – Fibrous connective tissue.– Cartilage.– Vascular tissue.– Lymphatic tissue.– Adipose tissue.– Nervous tissue
• All bones consist of a dense, solid outer layer known as compact bone and an inner layer of spongy bone – a honeycomb of flat, needle-like projections called trabeculae.
• The periosteum is a fibrous sheath that covers bones. It contains the blood vessels and nerves that provide nourishment and sensation to the bone.
• A thin layer of connective tissue that lines the walls of the bone marrow cavities and haversian canals of compact bone and covers the trabeculae of cancellous bone.
• Endosteum has both osteogenic and hematopoietic potencies and, like the periosteum, takes an active part in the healing of fractures.
Bone Structure• Bone tissue is a type of connective tissue, so it
must consist of cells plus a significant amount of extracellular matrix.
• Bone cells:1. Osteoblasts
• Bone-building cells.• Synthesize and secrete collagen fibers
and other organic components of bone matrix.
• Initiate the process of calcification.• Found in both the periosteum and the
endosteum
The blue arrows indicate the osteoblasts. The yellow arrows indicate the bone matrix they’ve just secreted.
2. Osteocytes• Mature bone cells.• Osteoblasts that have become trapped by
the secretion of matrix.• No longer secrete matrix.• Responsible for maintaining the bone
tissue.
The osteocyte is “trapped” within the pink matrix
3.Osteoclasts– Huge cells derived from the fusion of as many
as 50 monocytes (a type of white blood cell).– Cells that digest bone matrix – this process is
called bone resorption and is part of normal bone growth, development, maintenance, and repair.
– Concentrated in the endosteum.
Bone Matrix:– Consists of organic and inorganic
components.• Organic component consists of several
materials that are secreted by the osteoblasts:
–Collagen fibers and other organic materials
»These (particularly the collagen) provide the bone with resilience and the ability to resist stretching and twisting
• Inorganic component of bone matrix– Consists mainly of 2 salts: calcium phosphate
and calcium hydroxide.– Bone also contains smaller amounts of
magnesium, fluoride, and sodium.– These minerals give bone its characteristic
hardness and the ability to resist compression.
Long Bone Structure• Shaft plus 2 expanded ends.• Shaft is known as the
diaphysis.– Consists of a thick collar of
compact bone surrounding a central marrow cavity• In adults, the marrow
cavity contains fat - yellow bone marrow
• Expanded ends are epiphyses– Thin layer of compact bone covering an
interior of spongy bone.– Joint surface of each epiphysis is covered
with a type of hyaline cartilage known as articular cartilage. It cushions the bone ends and reduces friction during movement.
• The external surface of the entire bone except for the joint surfaces of the epiphyses is covered by a double-layered membrane known as the periosteum
• Periosteum is richly supplied with nerve fibers, lymphatic vessels and blood vessels.
• These enter the bone of the shaft via a nutrient foramen.
• Periosteum is connected to the bone matrix via strong strands of collagen
• Internal bone surfaces are covered with a delicate connective tissue membrane known as the endosteum.
• Covers the trabeculae of spongy bone in the marrow cavities and lines the canals that pass through compact bone.
• Contains both osteoblasts and osteoclasts.
Bone Marrow
• soft tissue occupying the medullary cavity of a long bone, the spaces amid the trabeculae of spongy bone, and the larger haversian canals.
• There are 2 main types: red & yellow.• Red bone marrow = blood cell forming
tissue = hematopoietic tissue
• Red bone marrow looks like blood but with a thicker consistency.
• It consists of a delicate mesh of reticular tissue saturated with immature red blood cells and scattered adipocytes
• Yellow marrow do not produce blood, although in the event of severe or chronic anemia, it can transform into red marrow
Microscopic Structure of Compact Bone• Consists of multiple cylindrical structural
units known as osteons or haversian systems
• Haversian systems are arranged parallel to one another along the long axis of a compact bone.
Osteons/ Haversian systems
• Each osteon consists of a single central canal, known as a haversian canal, surrounded by concentric layers of calcified bone matrix.
• Haversian canals allow the passage of blood vessels, lymphatic vessels, and nerve fibers.
• Each of the concentric matrix “tubes” that surrounds a haversian canal is known as a lamella.
• All the collagen fibers in a particular lamella run in a single direction, while collagen fibers in adjacent lamellae will run in the opposite direction. This allows bone to better withstand twisting forces
• Running perpendicular to the haversian canals are Volkmann’s canals.
• They connect the blood and nerve supply in the periosteum to those in the haversian canals and the medullary cavity.
• Spider-shaped osteocytes occupy small cavities known as lacunae at the junctions of the lamellae.
• Hairlike canals called canaliculi connect the lacunae to each other and to the central canal.
• Canaliculi allow the osteocytes to exchange nutrients, wastes, and chemical signals to each other via intercellular connections
Microscopic Structure of Spongy Bone
• Appears poorly organized compared to compact bone.
• Lacks osteons.• Trabeculae align along positions of stress
and exhibit extensive cross-bracing.• Trabeculae are a few cell layers thick and
contain irregularly arranged lamellae and osteocytes interconnected by canaliculi
SKELETON
Axial skeleton• skull (cranium and facial bones)• hyoid bone (anchors tongue and muscles
associated with swallowing)• vertebral column (vertebrae and disks)• thoracic cage (ribs and sternum)
Appendicular skeleton• pectoral girdle (clavicles and scapulae)• upper limbs (arms)• pelvic girdle (sacrum, coccyx)• lower limbs (legs)
22 bones in skull6 in middle ears1 hyoid bone26 in vertebral column25 in thoracic cage
4 in pectoral girdle60 in upper limbs60 in lower limbs2 in pelvic girdle
206 bones in all
Bone Surface Markings• Foramen = opening (arteries, nerves)• Fossa = shallow depression• Sulcus = shallow groove (artery or nerve)• Canal = longer, tubelike opening• Fissure = narrow, cleftlike opening• Notch = indentation at the end of a bone• Meatus = type of canal• Condyle = large, round protuberance, attachment of muscles• Epicondyle = above or upon a condyle• Facet = smooth flat articular surface• Trochanter = very large projection• Tuberosity = large, rounded, roughened projection• Tubercle = rounded eminence/elevation• Crest = roughened border or ridge• Spine = sharply pointed projection
Axial skeleton
The skull
• 8 sutured bones in cranium• Facial bones: 13 sutured bones, 1
mandible
• Cranium - encases brain - attachments for muscles - sinuses
Cranial Bones
• Parietal (2) • Temporal (2) • Frontal (1) • Occipital (1) • Sphenoid (1)• Ethmoid (1)
Sutures• Sutures are the tight connections between
skull bones• In the adult skull , the skull bones are
unable to move or separate due to this tight connections
• In infant skull this sutures are not well formed and the skull bones are mobile which facilitates the delivery of the baby
• Coronal suture – this separates the frontal from the parietal bones
• Sagittal suture - this separates the two parietal bones in the mid line
• Lambdoid suture - this separates the occipital bone the two parietal bones and the temporal bone
• Squamosal suture - this separates the temporal from the parietal bones
Fontanelles
• These are seen in new borns• At birth the junction between skull bones
covered with a membrane • This allows the expansion and growth of
the brain• Later they become ossified ( bone
formation)
Lateral view
Anterior view
Inferior view
• Warm and moisten air• Lighten the skull• Enhance voice resonance
Frontal Sinus
Ethmoid SinusSphenoid Sinus
Maxillary Sinus
Sinuses
Frontal bone– Forms the forehead– Roof of the orbit– articulates with parietal, sphenoid, lacrimal,
nasal, ethmoid, zygomatic and maxilla– Contain 2 air filled cavities. ( frontal sinuses
Parietal bones– Part of the superior and lateral surfaces of the
cranium– -articulate with each other – sagittal suture– -articulate with occipital, frontal,– temporal and sphenoid bones
Temporal bone– Forms wall of jugular foramen– Associated with ear canal– Anterior portion, fan-shaped - zygomatic process -forms cranial portion of the TMJ joint -inferior to zygo. process – mandibular
fossa (mandibular condyle)- inferior aspect – mastoid process- inferior and medial to the MP – styloid
process
Occipital bone• Part of the base of the skull• articulates with parietal, temporal and
sphenoid• Surrounds the foramen magnum• Occipital condyles articulate with Atlas
Sphenoid bone
– Contributes to floor of cranium– articulates with the frontal, ethmoid, temporal zygomatic, parietal maxillary, palatine, vomer
& occipital bones– Bridges cranial and facial bones– Optic canal allows passage of optic nerve
Ethmoid bone
– Irregularly shaped bone– Forms part of orbital wall– Forms roof of nasal cavity– articulates with: frontal, sphenoid, lacrimal
and maxillary bones– connects with the vomer
Facial Bones
Nasal (2) Maxillae (2) Zygomatic (2)Mandible (1) Lacrimal (2) Palatine (2)
Inferior nasal conchae (2) Vomer (1)
Maxillae
– Paired bone– Largest of facial bones– Form upper jaw– contains the maxillary sinuses– zygomatic process: articulates with
zygomatic bone– Teeth are fixed to this
Zygomatic Bones - Lateral wall of orbit form along with
sphenoid - Part of zygomatic arch form along with part
of temporal
Palatine bones– Small, L-shaped– link between maxilla and sphenoid– Form posterior portion of hard palate– Contribute to floor of orbit
Lacrimal bones
– Smallest bones in skull– Forms nasolacrimal groove leading to
nasolacrimal canal– Delivers tears to nasal cavity
Vomer
– Forms posterior part of nasal septum– Forms inferior portion of nasal septum– Articulates with maxillae and palatines
Nasal bones– Paired bones – forms the bridge– Articulate with frontal bone
Mandible• lower jaw carries teeth• only freely movable bone of the skull• moving articulations with temporal bone
Orbital complex– Bony recess that holds the eye– Seven bones
• Frontal bone• Lacrimal bones• Palatine bones• Zygomatic bones• Ethmoid• Sphenoid• Maxillae
Bones forming the walls of the orbit
• Roof - frontal lesser wing of sphenoid• Medial wall – maxilla lacrimal ethmoid sphenoid• Floor – maxilla zygomatic palatine
• Lateral wall - greater wing of sphenoid zygomatic
Cranial Fossae
• Depressions in cranial floor• Anterior cranial fossa
– Frontal bone, ethmoid, lesser wings of sphenoid
• Middle cranial fossa– Sphenoid, temporal bones, parietal bones
• Posterior cranial fossa– Occipital bone, temporal bones, parietal
bones
Vertebral column
• Cervical vertebrae (7) • Thoracic vertebrae (12) • Lumbar vertebrae (5) • Sacrum (5 pieces) • Coccyx (4 pieces) • Total number is 33
Typical Vertebrae• Body
– weight bearing• Vertebral arch
– pedicles– laminae
• Vertebral foramen• Seven processes
– 2 transverse– 1 spinous – 4 articular
• Vertebral notches
• Vertebral body lies anteriorly• Vertebral foramen lies posterior to
vertebral body , which allows spinal cord to pass
• Vertebral arch a curved bony structure which surrounds the foramen
• Spinous process lies posteriorly• Transverse processes lie lateraly
Atlas (C1)• ring of bone, superior facets for occipital
condyles– nodding movement at atlanto-occipital joint
signifies “yes”
Axis(C2)• dens or odontoid process is body of
atlas– movement at atlanto-axial joint signifies “no”
Cervical Vertebrae (C3-C7)
• Smaller bodies• Larger spinal canal• Transverse processes
– shorter– transverse foramen for vertebral artery
• Spinous processes of C2 to C6 often bifid
Thoracic Vertebrae(T1-T12)
• Larger and stronger bodies which carry the shape of the heart
• Longer transverse & spinous processes• Facets on body for head of rib• Facets on transverse processes (T1-T10)
for tubercle of rib
Lumbar Vertebrae
• Strongest & largest for weight baring• Body takes the shape of kidney• Short thick spinous & transverse
processes– back musculature
Sacrum and Coccyx
• Sacrum – Triangular shaped bone formed by united 5 sacral bodies
• Coccyx – Most inferior part of the vertebral column and it is made up of 4 united vertebral bodies
Spinal Canal
• Spinal canal is all vertebral foramen together
• Carries the spinal cord
Intervertebral Foramen
• These are small fenestrations on the lateral sides of the vertebral column
• These lie in between two vertebrae• The nerves which arises from the spinal
cord exit from there
The intervertebral disc
• The intervertebral disc lies between two vertebrae
• Made up of fibrous cartilage and a jelly like substance
• Function is to reduce friction between the vertebral bodies and neutralize mechanical shock
Thoracic cage
• The thoracic cage is formed by;Anteriorly – Sternum and the costal
cartilagesPosteriorly - Thoracic vertebraeSuperiorly – Thoracic inlet Inferiorly – DiaphragmLaterally – Ribs ( Rib cage)
Sternum
• A flat bone which forms the anterior part of the thoracic cage
• Consist of 3 parts - Manubrium - Body of the sternum - Xiphoid process
• Between the manubrium and the body of the sternum lies the sternal angle ( Angle of Louis)
• The second rib is attached to the sternum at the Angle of Louis
Ribs
• Thoracic cage is formed by twelve pairs of ribs
• All ribs posteriorly attached to the vertebrae
• Anteriorly upper 7 ribs directly attached to the sternum via costal cartilages
• 8th, 9th and 10th ribs are attached to the cartilage of the rib above ( False ribs)
• 11th and 12th are not attached to the sternum ( Floating ribs)
Costal Groove• Each rib has a costal groove in it’s lower
inner surface • The intercostal vein, artery and the nerve
lies in this groove
Intercostal space
• This space carries the intercostal vessels and nerves and is filled by the inercostal muscles
• The function of inercostal muscles are to facilitate inspiration and expiration
Function of the thoracic cage
• Provide protection for the internal organs – heart, lungs
• Facilitates the expansion of the lung during inspiration
Shoulder Girdle
• Formed by the Clavicle and the Scapula
The scapula• Is a triangular shaped bone which lies on
the posterior surface of the rib cage• The Acromion process projects lateraly and
attached with the clavicle to form acromio-clavicular joint
• The Glenoid cavity is a shallow cavity which attached with the head of the humerus forming shoulder joint (bowel and socket joint)
The Clavicle
• A ‘S’ shaped bone attached medially to the sternum by sterno-clavicular joint
• Laterally attached to the scapular by acromio-clavicular joint
• Commonly get fractures
Upper limb
• Arm – Humerus• Forearm – Ulnar , Radius• Wrist – 8 Carpal bones• Hand – Metacarpal bones• Fingers – Phalanges
The bones of the upper limb
Humerus
• Longest bone in the upper limb• Head of the humerus lies in the proximal
end and articulates with the glenoid cavity to form shoulder joint
• Distal end articulates with ulnar and radius forming the elbow joint
Ulnar
• Longest bone in the forearm• Lies medially• Proximally form elbow joint with the
humerus• Distally form wrist joint with carpal bones
Radius
• Shorter than ulnar• Lies lateral to ulnar• Proximally form elbow joint with humerus• Distally form wrist joint with carpal bones
Carpal bones
• Lie in 2 rows at wrist• Proximal row – Scaphoid, Lunate,
Triquatral, Pisiform• Distal row – Trapezium, Trapezoid,
Capitate, Hamate
Metacarpal bones
• 5 Metacarpal bones form the palm of the hand
Phalanges• Thumb – 2 Phalanges (Proximal, Distal)• Other 4 fingers – 3 Phalanges ( Proximal,
Middle, Distal)
Pelvic Girdle
• The pelvic girdle is formed by the bony pelvis
• The bony pelvis is made from the right and left pelvic bones which form the lateral wall, the pubic symphysis which is the junction between the two pelvic bones anteriorly and the sacrum which lie posteriorly
Pelvic bones
• Consist of 3 irregular flat bones in each which have fused completely
• Iliac bone – A large fan shaped bone. Upper edge is the iliac crest which extend from anterior superior iliac spine to posterior superior iliac spine
• Ischial bone – Irregular bone, has an ischial spine which project inward.
Ischial tuberosity lies at the most inferior edge
• Pubic bone – Consist of the body of the pubis, superior and inferior pubic rami.
The two bodies of the pubis of each pubic bone join anteriorly at the pubic symphasis
The differences between the male and the female pelvis
Female• Light and thin• Oval shape• Large pelvic outlet• Wide pubic angle• Wide sacrum
Male• Thick and heavy• Heart shape• Small pelvic outlet• Narrow pubic angle• Narrow sacrum
Lower Limb• Thigh – Femur• Leg – Tibia , Fibula• Knee – Patella• Ankle – 7 Small bones• Foot – 5 Metatarsals• Toes – Phalanges
Femur
• Largest and the strongest bone• Head of the femur joints with the
acetabulum of the pelvic bone and forms Hip joint
• Other important parts include the neck of the femur, shaft and the medial and lateral condyle which form knee joint with the combination of tibia
Patella• Small triangular bone which form the knee
cap
Tibia• Lie in the medial side of the leg• Upper end articulate with the femur to form
knee joint• Lower end of the shaft has the medial
malleolus on its medial side
Fibula
• Smaller than tibia• Lies laterally• Lower end has the lateral malleolus on its
lateral side
Ankle Bones
• The 7 ankle bones are the talus, calcaneus (heel bone), navicular, cuboid, internal cuneiform, middle cuneiform, and external cuneiform
• Talus joins with tibia and fibula forming the ankle joint
Questions
1. What is Fracture neck of femur?2. What is osteomyelitis?3. What is osteoporosis?4. What is infective arthritis?
Types of movement and examples flexion- move lower leg toward upperextension- straightening the leg
abduction- moving leg away from bodyadduction- movong leg toward the body
rotation- around its axissupination- rotation of arm to palm-up positionpronation- palm down
circumduction- swinging arms in circles
inversion- turning foot so sole is inwardeversion- sole is out
Elevation and depression- raising body part upor down