skeletal system lecture

7/27/2019 SKELETAL SYSTEM LECTURE

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Chapter 7Anatomy of Bones

and Joints

Bone Trabeculae


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General Considerations of Bones

Average adult skeleton has 206 bones (Figure 7.1)

Bones are paired or unpaired

Most anatomical terms used to describe the featuresof bones are based on the relationship between thebones and associated ligaments, muscles, joints,nerves, and blood vessels (Table 7.1) Processes

Surfaces

Holes The skeleton is divided into the axial and

appendicularskeletons


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Fig 7.1


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Tab. 7.1


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Axial Skeleton

The axial skeleton forms the upright axis of thebody

Consists of

Skull Auditory ossicles

Hyoid bone

Vertebral column

Thoracic cage (rib cage)

Protects the brain, the spinal cord, and the vital

organs housed within the thorax


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Axial Skeleton

Skull Composed of 22 bones

The braincase protects the brain Paired parietal and temporal bones, and the unpaired

frontal, occipital, sphenoid, and ethmoid bones The facial bones protect the sensory organs of the

head and serve as muscle attachment sites The 14 facial bones are the maxilla (2), zygomatic (2),

palatine (2), lacrimal (2), nasal (2), inferior nasal concha

(2), mandible (1), and vomer (1) bones The mandible and maxillae hold the teeth, and the

auditory ossicles that function in hearing, arelocated inside the temporal bones


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Axial Skeleton

Skull (External view) Parietal bones

Joined at the midline by the sagittal suture

Joined to the frontal bone by the coronal suture

Joined to the occipital bone by the lambdoid suture

Joined to the temporal bone by the squamoussuture

The external occipital protuberance is an

attachment site for an elastic ligament

Nuchal lines are the points of attachment forneck muscles


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Fig 7.2


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Fig 7.3


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Axial Skeleton

Skull (Lateral view) The external acoustic meatus transmits sound

waves toward the eardrum

Neck muscles attach to the mastoid process,which contains mastoid air cells

The temporal lines are attachment points ofthe temporalis muscle

The zygomatic arch, from the temporal andzygomatic bones forms a bridge across theside of the skull

The mandible articulates with the temporal

bone


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Fig 7.4


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Fig 7.5


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Axial Skeleton

Skull (Anterior view) The orbits contain the eyes

The nasal cavity is divided by the nasalseptum

Sinuses within bone are air-filled cavities The paranasal sinuses, which connect to the nasal

cavity, are the Frontal sinus

Sphenoidal sinus

Maxillary sinuses

Ethmoidal labyrinth


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Fig 7.6


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Fig 7.7


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Fig 7.8


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Fig 7.9


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Fig 7.10


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Axial Skeleton

Skull (Inferior surface) Spinal cord and brain are connected through

the foramen magnum

Occipital condyles are points of articulationbetween the skull and the vertebral column

Blood reaches the brain through the internal

carotid arteries, which pass through the

carotid canals, and the vertebral arteries,which pass through the foramen magnum


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Axial Skeleton

Skull (Inferior surface) Most blood leaves the brain through the

internal jugular veins, which exit through the

jugular foramina Styloid processes provide attachment points

for three muscles involved in movement of the

tongue, hyoid bone, and pharynx

The hard palate separates the oral cavity fromthe nasal cavity


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Fig 7.11


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Axial Skeleton

Skull (Superior view inside the cranialcavity)

The crista galli is a point of attachment for one

of the meninges The olfactory nerves extend into the roof of

the nasal cavity through the olfactory foramina

of the cribriform plate

The sella turcica is occupied by the pituitary

gland


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Tab. 7.2


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Tab. 7.3


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Fig 7.12


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Axial Skeleton

The hyoid bone,which floats in

the neck, is the

attachment sitefor throat and

tongue muscles

Fig 7.13


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Axial Skeleton

Vertebral Column Provides flexible support and protects the spinal

cord

The vertebral column has four major curvatures: Cervical

Thoracic

Lumbar

Sacral/CoccygealAbnormal curvatures are

lordosis (lumbar)

kyphosis (thoracic)

scoliosis (lateral)


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Fig 7.14


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Fig 7.15


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Axial Skeleton

Vertebral Column (Vertebra) Consists of a body, a vertebral arch, and various

processes Part of the body and vertebral arch (pedicle and lamina) form

the vertebral foramen, which contains and protects the spinal

cord The transverse and spinous processes are points of muscle

and ligament attachment

Vertebrae articulate with one another through the superiorand inferior articular processes

Spinal nerves exit through the intervertebral foramina Adjacent bodies are separated by intervertebral disks

Fibrous outer covering (annulus fibrosus)

Gelatinous interior (nucleus pulposus)


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Fig 7.16


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Tab. 7.4


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Axial Skeleton

Vertebral Column Components All seven cervical vertebrae have transverse

foramina, and most have bifid spinous processes

The 12 thoracic vertebrae have attachment sites forribs and are characterized by long, downward-pointing spinous processes

The five lumbar vertebrae have thick, heavy bodiesand processes. Their superior articular facets facemedially and their inferior articular facets face laterally

The sacrum consists of five fused vertebrae andattaches to the coxal bones to form the pelvis

The coccyx consists of four fused vertebrae attachedto the sacrum


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Fig 7.17


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Fig 7.18


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Tab.

7.4(Contd.)


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Tab. 7.5


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Page

160.a


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Page

160.b


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Axial Skeleton

Thoracic Cage The thoracic cage (consisting of the ribs, their

associated costal cartilages, and the sternum)protects the thoracic organs and changes volumeduring respiration

Twelve pairs of ribs attach to the thoracic vertebrae Seven pairs oftrue ribs

Five pairs offalse ribs

Two pairs of false ribs are floating

The sternum is composed of the Manubrium

Body

Xiphoid process


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Fig 7.19


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Fig 7.20


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Appendicular Skeleton

Consists of the bones of the upperandlower limbs and the girdles by which they

are attached to the body

Pectoral girdle: upper limbs Pelvic girdle: lower limbs


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Pectoral Girdle Consists of the scapulae and clavicles

Scapula Articulates with the humerus (at the glenoid cavity)

and the clavicle (at the acromion) Attachment site for shoulder, back and arm

muscles

Clavicle

Holds the shoulder away from the body and allowsmovement of the scapula, resulting in freemovement of the arm


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Fig 7.21


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Fig 7.22


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Fig 7.23


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Upper Limb The arm bone is the humerus

Articulates with the scapula (head), the radius(capitulum), and the ulna (trochlea)

Sites of muscle attachment are the greater andlesser tubercles, the deltoid tuberosity, and theepicondyles

The forearm contains the ulna and radius

The ulna and radius articulate with each other andwith the humerus and wrist bones

The wrist ligaments attach to the styloid processesof the radius and ulna


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Fig 7.24


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Fig 7 25

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