SKELETAL SYSTEM n COMPOSED OF Bones Cartilage Joints

SKELETAL SYSTEM n COMPOSED OF: -Bones -Cartilage -Joints -Ligaments

Functions of Skeletal System n SUPPORT: Hard framework that supports and anchors the soft organs of the body. n PROTECTION: Surrounds organs such as the brain and spinal cord. n MOVEMENT: Allows for muscle attachment therefore the bones are used as levers. n STORAGE: Minerals and lipids are stored within bone material. n BLOOD CELL FORMATION: The bone marrow is responsible for blood cell production.

Bone Markings · Bone Surface is not smooth, but shows markings which reveal where: -muscles, tendons, and ligaments are attached -nerves and blood vessels pass *bone marking may be: 1 -projections or processes or 2 -depressions or cavities Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 5. 9

Classification of bones 1 -According to structure n n Compact bone n Outer layer of bone, very hard and dense. n Organized in structural units called Haversian systems. n Matrix is composed of Ca salts (Ca carbonate and Ca phosphate) n Osteocytes – living bone cells that live in matrix. Porous (Spongy) bone n Located in the ends of long bones. n Many spaces that are filled with red bone marrow which produces bone cells.

2 -According to the shape · Long bones · Typically longer than wide · Have a shaft with heads at both ends · Contain mostly compact bone • Examples: Femur, humerus · Short bones · Generally cube-shape · Contain mostly spongy bone · Examples: Carpals, tarsals Slide 5. 4 a

· Flat bones · Thin and flattened · Usually curved · Thin layers of compact bone around a layer of spongy bone · Examples: Skull, ribs, sternum · Irregular bones · Irregular shape · Do not fit into other bone classification categories Slide 5. 5 a

Macroscopic natomy of a Long Bone · Diaphysis · Shaft · Composed of compact bone · Epiphysis · Ends of the bone · Composed mostly of spongy bone Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Figure 5. 2 a Slide 5. 6

Classification of Bones on the Basis of Shape Figure 5. 1 Slide 5. 4 c

· Periosteum · Outside covering of the diaphysis · Fibrous connective tissue membrane · Sharpey’s fibers · Secure periosteum to underlying bone · Arteries · Supply bone cells with nutrients Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Figure 5. 2 c Slide 5. 7

· Articular cartilage · Covers the external surface of the epiphyses · Made of hyaline cartilage · Decreases friction at joint surfaces Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Figure 5. 2 a Slide 5. 8 a

· Medullary cavity · Cavity of the shaft · Contains yellow marrow (mostly fat) in adults · Contains red marrow (for blood cell formation) in infants Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Figure 5. 2 a Slide 5. 8 b

Microscopic anatomy of Bone · Osteon (Haversian System) is the unit of bone structure which consists of: - Central (Haversian) canal · Opening in the center of an osteon · Carries blood vessels and nerves - Perforating (Volkman’s) canal · Perpendicular to the central canal · Carries blood vessels and nerves Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 5. 10 a

Figure 5. 3 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 5. 10 b

· Lacunae · Cavities containing bone cells (osteocytes) · Arranged in concentric rings called lamellae · Lamellae · concentric rings around the central canal Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Figure 5. 3 Slide 5. 11 a

· Canaliculi · Tiny canals · Radiate from the central canal to the lacunae · Form a transport system Figure 5. 3 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 5. 11 b

Changes in the Human Skeleton · In embryos, the skeleton is primarily hyaline cartilage · During development, much of this cartilage is replaced by bone · Cartilage remains in isolated areas · Bridge of the nose · Parts of ribs · Joints Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 5. 12

Bone Growth · Epiphyseal plates allow for growth of long bones during childhood · New cartilage is continuously formed · Older cartilage becomes ossified · Bones are remodeled and lengthened until growth stops · Bones change shape by gravity &muscle pull · Bones grow in width through periosteum Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 5. 13 a

Long Bone Formation and Growth Figure 5. 4 a Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 5. 14 a

Types of Bone Cells · Osteocytes · Mature bone cells · Osteoblasts · Bone-forming cells · Osteoclasts · Bone-destroying cells · Break down bone matrix for remodeling and release of calcium · Bone remodeling is a process by both osteoblasts and osteoclasts Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 5. 15

Fractures Closed fracture (simple): skin is intact n Open fracture (compound): skin is open n Fracture reduction : 1 -closed reduction , no surgery is needed 2 -open reduction , surgery is needed n

Repair of fracture n n n Healing time for simple fracture is 6 -8 weeks (longer in elderly people) It occurs in FOUR major events 1 -hematoma formation 2 -fibrocartilage callus formation 3 -bony callus formation 4 -bone remodeling

Division of the Skeletal system n Axial skeleton n Skull and associated bones n Auditory ossicles n Hyoid bones n Vertebral column n Thoracic cage(Ribs+ sternum) § Appendicular skeleton -Pectoral girdle +upper limb -Pelvic girdle +lower limb

The Axial Skeleton n Skull and associated bones: n n Auditory ossicles Hyoid bones Vertebral column Thoracic cage n Ribs + sternum

The Skull and Associated Bones

Sutures n Most skull bones are flat bones. Except for the mandible, which is connected to the rest of the skull by a freely movable joint, all bones of the adult skull are firmly united by interlocking joints called sutures (soo′cherz). The suture lines have a sawtoothed or serrated appearance. The major skull sutures are: n Coronal – between parietal and frontal n Sagittal– between parietal bones n Lambdoid – between the parietal and occipital n Squamous – between the parietal and temporal

Fontanels: From each center of ossification, bone growth radiates outward as calcium salts are deposited in the collagen of the model of the bone. This process is not complete at birth; a baby has areas of fibrous connective tissue remaining between the bones of the skull. These are called fontanels , which permit: -compression of the baby’s head during birth without breaking the still thin cranial bones. -the growth of the brain after birth. *By the age of 2 years, all the fontanels have become ossified, and the skull becomes a more effective protective covering for the brain.

The Adult Skull • skull = 22 bones • cranium = 8 bones: frontal, occipital, 2 temporals, 2 parietals, sphenoid and ethmoid • facial bones = 14 bones: nasals, maxillae, zygomatics, mandible, lacrimals, palatines, inferior nasal conchae, vomer. • skull forms a larger cranial cavity -also has the nasal cavity, the orbits and paranasal sinuses • Mandible and auditory ossicles are the only movable skull bones • outer surface provides large areas for muscle attachment that move the head or provide facial expressions. • Attached to its inner surfaces are membranes called

Figure 6. 4 Sectional Anatomy of the Skull, Part I

14 Facial Bones Nasal (2) Mandible (1) Palatine (2) Maxillae (2) Zygomatic (2) Lacrimal (2) Inferior nasal conchae (2) Vomer (1)

Bones of the Face n Maxillae Paired bone n Largest of facial bones n Form upper jaw n body = orbital, nasal, infratemporal and facial surfaces n body contains the maxillary sinuses n

n Palatine bones Form posterior portion of hard palate - The anterior portion of the hard palate is made by the palatine process of the maxillae n

n n n Mandible lower jaw only freely movable bone of the skull articulations with temporal bone in temperomandibular joint.

The Hyoid Bone n n n Suspended by stylohyoid ligaments Consists of a body, greater horns and lesser horns Base for muscles of the tongue and larynx

Paranasal Sinuses -Lined with mucous membranes and open into nasal cavity though openings called ostia -Resonating chambers for voice, lighten the skull - Four sinuses: n frontal sinus: n sphenoid sinus: n ethmoid sinus: n maxillary sinus which is: n The largest of the sinuses n close to the upper alveolar margin -Sinusitis is inflammation of the sinuses. It can easily spread from the nose to any sinus and from one sinus to the other as mucous membrane is continuous.

Adult Vertebral Column n 26 vertebrae 24 individual vertebrae n Sacrum n Coccyx n Seven cervical vertebrae n Twelve thoracic vertebrae n Five lumbar vertebrae n Sacrum and coccyx are Fused together. n

Typical Vertebrae n Body n n weight bearing Vertebral arch pedicles n laminae n n n Vertebral foramen Seven processes 2 transverse n 1 spinous n 4 articular n

Typical Cervical Vert. (C 3 -C 7) n n n Smaller bodies Larger spinal canal Transverse processes n n shorter transverse foramen for vertebral artery Spinous processes of C 2 to C 6 often bifid 1 st and 2 nd cervical vertebrae are unique n atlas & axis

Atlas & Axis (C 1 -C 2)

The Atlas n n n C 1 is termed the atlas Lacks a body and spinous process Supports the skull n n Superior articular facets receive the occipital condyles Allows flexion and extension of neck n Nodding the head “yes”

The Atlas Figure 7. 16 a

The Axis n n Has a body and spinous process Dens (odontoid process) projects superiorly Acts as a pivot for rotation of the atlas and skull n Participates in rotating the head from side to side n

The Axis

Sacrum (S 1 – S 5) n n n Forms the posterior wall of pelvis Formed from 5 fused vertebrae Superior surface articulates with L 5 Inferiorly articulates with coccyx Sacral promontory n Where the first sacral vertebrae bulges into pelvic cavity Center of gravity is 1 cm posterior to sacral promontory Coccyx Is the “tailbone” n Formed from 3 – 5 fused vertebrae n Offers only slight support to pelvic organs n

Sacrum Figure 7. 18 a, b

Bony Thorax n n Forms the framework of the chest Components of the bony thorax Thoracic vertebrae – posteriorly n Ribs – laterally n Sternum and costal cartilage – anteriorly n n Protects thoracic organs Supports shoulder girdle and upper limbs Provides attachment sites for muscles

The Bony Thorax Figure 7. 19 a

The Bony Thorax Figure 7. 19 b

Sternum n n Formed from three parts : n Manubrium – superior part n Articulates with medial end of clavicles n Body – bulk of sternum n Sides are notched as articulations for costal cartilage of ribs 2– 7 n Xiphoid process – inferior end of sternum n Ossifies around age 40 Anatomical landmarks n Jugular notch n Central indentation at superior border of the manubrium n Sternal angle n A horizontal ridge where the manubrium joins the body, it is at the level of the second rib.

Ribs n All ribs attach to vertebral column posteriorly n True ribs - superior seven pairs of ribs n n Attach to sternum by costal cartilage False ribs – inferior five pairs of ribs , attatch indirectly to the sternum nfloating ribs 11– 12 are short and free anteriuorly.

Ribs Figure 7. 20 a

Ribs Figure 7. 20 b

Disorders of the Axial Skeleton n Abnormal spinal curvatures Scoliosis – an abnormal lateral curvature n Kyphosis – an exaggerated thoracic curvature n Lordosis – an accentuated lumbar curvature – “swayback” n n Stenosis of the lumbar spine n A narrowing of the vertebral canal

The Appendicular Skeleton Allows us to move and manipulate objects n Includes all bones other than axial skeleton, it includes: n n n the supportive girdles (pectoral &pelvic girdles) the limbs (upper & lower limbs)

th Figure 8– 1

The Pectoral Girdle (Shoulder girdle) Consists of: 2 clavicles 2 scapulae Connects with the axial skeleton only at the manubrium (claviculosternal joint) Figure 8– 2 a

The Clavicles Figure 8– 2 b, c

The Clavicles n n Also called collarbones Long, S-shaped bones Originate at the manubrium (sternal end) Articulate with the scapulae (acromial end) The Scapulae n n n Also called shoulder blades Broad, flat and triangular Articulate with arms and collarbone

Anatomy of The scapula Figure 8– 3 a

Bones of the upper limb -The Humerus -Also called the arm -The long, upper armbone -Articulates with the pectoral girdle Figure 8– 4

The Forearm -Also called the antebrachium -Consists of 2 long bones: ulna (medial) radius (lateral) Figure 8– 5

The Wrist Figure 8– 6

The Wrist n n n - 8 carpal bones: n 4 proximal carpal bones n 4 distal carpal bones n allow wrist to bend and twist -5 Metacarpal Bones The 5 long bones of the hand Numbered I–V from lateral (thumb) to medial Articulate with proximal phalanges -14 Phalanges Pollex (thumb): 2 phalanges (proximal, distal phalanx) Fingers: 3 phalanges (proximal, middle, distal phalanx)

Pelvic girdle: two ossa coxae, sacrum and coccyx

The OSSA COXAE n n n Also called hipbones Strong to bear body weight &stress of movement Each is made up of 3 fused bones: n ilium n n n (articulates with sacrum) n ischium n Pubis The Acetabulum (vinegar cup) Also called the hip socket Is the meeting point of the ilium, ischium, and pubis Articulates with head of the femur (Hip joint).

Landmarks of the Pubis n Pubic symphysis: n gap between pubic tubercles n padded with fibrocartilage Landmarks of the Ischium • Ischial tuberosity: posterior projection you sit on • Ischeal spine, superior to the tuberosity , important during labour

Divisions of the Pelvis Figure 8– 9

Comparing the Male and Female Pelvis n Female pelvis is: n smoother n lighter n less prominent muscle and ligament attachments Pelvis Modifications for Childbearing n n n Enlarged pelvic outlet Broad pubic angle (> 100°) Less curvature of sacrum and coccyx Wide, circular pelvic inlet Ilia project laterally.

Comparing the Male and Female Pelvis Figure 8– 10

Bones of the Lower Limbs n Femur (thigh) n Patella (kneecap) n Tibia and fibula (leg) n Tarsals (ankle) n Metatarsals (foot) n Phalanges (toes)

The Femur(longest, heaviest bone in the body ) Figure 8– 11

The Tibia and Fibula Figure 8– 13

The Tibia n n Also called the shinbone Supports body weight Larger than fibula Medial to fibula The Fibula • Attaches muscles of feet and toes • Smaller than tibia • Lateral to tibia

The Ankle n n n Also called the tarsus: consists of 7 tarsal bones. Calcaneus (heel bone): transfers weight to ground n attaches Achilles tendon n Figure 8– 14 a

n n n Metatarsal Bones 5 long bones of foot Numbered I–V, medial to lateral Articulate with toes Phalanges : bones of the toes Hallux: n big toe, 2 phalanges (distal, proximal) Other 4 toes: n 3 phalanges (distal, medial, proximal)

Arches of the foot : Bones are arranged to form -THREE strong arches, 2 longitudinal (medial & lateral & 1 transverse -Ligaments & tendons help to hold the bones firmly in the arched position but still allow a certain amount of spriginess. Week arches are referred to as flat foot Figure 8– 14 b

Articulations (Joints) -Functions Holds bones together n Allows bones to move n All bones articulate with at least one other bone except the hyoid. -Synovial Joints – Structure 1. Articular cartilage: hyaline 2. Joint Cavity: space filled with lubricating fluid 3. Fibrous Capsule: fibrous CT lined with a smooth synovial membrane 4. Reinforcing Ligament: can be inside or outside the joint capsule n

Ball-and-socket joints n n n A spherical head of one bone fits into a round socket in another These Multiaxial joints allow movements in all axes including rotation Shoulder and Hip are examples

Developmental aspects n n n Long bones are formed on top of Hyaline cartilage Flat bones of skull are formed on top of fibrous membranes At birth, some fontanels still remain By end of adolescence, the epiphysial plates are fully ossified Adult skull is 1/8 & infant skull is 1/4 of the total body length

n n n At birth, cranium is huge relative to face, it is related to rapid growth of brain By 2 years skull is 3/4 adult size By 9 years, skull become nearly of adult size At birth, the spine is arched (primary) and convex posteriorly Secondary curvature are convex anteriorly, cervical with raising the head & lumber with start of walking S-shaped spine in adult

At birth the UL ratio is 1. 7 to 1 n At 10, UL is 1 to 1 n Bones become stronger with pull of gravity &muscle contractions n Osteoporosis (thin and fragile bones) occurs in totally inactive persons. It occurs in half women after 65 and in 20% of men after 70(estrogen maintain healthy bones) n Causes of Osteoporosis: - estrogen deficiency - diet poor in calcium & protein - lack of vitamin D - smoking - lack of exercise * pathologic fracture is the result END of Sk. system n