Anatomy Presentation Ho10(thorax 1)

The Thorax

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The thorax (chest) is the superior part of the trunk between the neck and abdomen. The thoracic cavity, surrounded by the thoracic wall ,contains the heart, lungs, thymus, distal part of the trachea, and most of the esophagus. To perform a physical examination of the thorax, a working knowledge of its structure and vital organs is

Thoracic Wall 2

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The thoracic wall consists of 

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skin, fascia, nerves, vessels, muscles, and bones.

The functions of the thoracic wall include  

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protecting of the thoracic and abdominal internal organs; resisting the negative internal pressures generated by the elastic recoil of the lungs and inspiratory movements; providing attachment for and supporting the weight of the upper limbs; and providing attachment for many of the muscles of the upper limbs, neck, abdomen and back, and the muscles of respiration. The mammary glands of the

Skin of the Thorax 3

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The thoracic skin is relatively thin and contains a variable amount of hair, which depends on age, sex and race; i.e. its amount is genetically determined. Thoracic hair is abundant in males than in females. It is found in a higher density at the median plane and extends to the anterior abdominal wall for a variable distance. In male the amount of hair on the chest and on the head are inversely

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Blood Vessels of the Skin of the Thorax  Arteries

- cutaneous branches of lateral thoracic and intercostal arteries  Veins - drain into lateral thoracic, thoracoepigastric and intercostal veins 

Innervation of the Skin of the Thorax  The

thoracic wall is innervated by the cutaneous branches of the segmental ventral rami spinal nerves and by supraclavicular nerves

Fascia of the Thorax 5 

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The fascia of the thorax can be divided into two: The outer thoracic fascia  

on the outside of the thoracic wall having its own two layers Superficial layer 

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Deep layer 

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a part of the superficial fascia of the body containing the breast, which is fibrous and tough a thin layer inseparable from the epimysium of the underlying muscles, except dorsally where it forms the thick thoracolumbar fascia

The inner endothoracic fascia 

 

found on the inner surface of the thoracic wall covering the thoracic surface of the ribs, muscles and diaphragm. Internally it is related to the parietal pleura. Its part covering the cervical pleura (cupola) is known as suprapleural membrane

Skeleton of Thoracic Wall 6 

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The thoracic skeleton forms the osteocartilaginous thoracic cage The thoracic skeleton (bony thorax) includes  

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12 pairs of ribs and costal cartilages, 12 thoracic vertebrae and intervertebral (IV) discs, and the sternum.

Costal cartilages form the anterior continuation of the ribs, providing a flexible attachment at their articulation with the sternum Ribs and their cartilages are separated by

Skeleton of Thoracic Wall 7

The Bony Thorax

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Sternum

 Manubrium,

Body (Gladiolus), Xiphoid Process

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Ribs 7

True Ribs  5 False Ribs   

Clavicle Scapula Vertebrae  Cervical,Thoracic,

Lumbar, Sacral (Sacrum), Coccygeal

Projections and Depressions 9

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Site of muscle and ligament attachments  Spine  Process

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Help form joints  Head  Facet

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Allow BV, nerves, and muscles to pass  Notch  Fossa

Thoracic Cage 10

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Borders:  Thoracic

vertebrae posteriorly  Ribs laterally  Sternum and costal cartilages anteriorly 

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Forms protective cage around heart, lungs, and other organs Composed of:  Sternum

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The Sternum (Composed of fused sternebrae)  Manubrium  Jugular

(sternal) notch  Articulation with rib #1 & 2  Clavicular Articular facets  Sternal Angle – 2nd rib 

Body (Gladiolus)  Articulates

w/ribs 2-7  Xiphosternal joint 

Xiphoid process  Cartilage-calcifies

thru

The Ribs 12

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Usually, 12 pairs 7

True ribs-direct attachment to sternum  5 False ribs-indirect or no attachment to sternum  Floating ribs-make up 2 of 5 False ribs, no ventral attachment 

Typical Ribs  Ribs

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# 2-9

Atypical Ribs

Typical rib. The features (A) and midbody cross section (B) of a typical rib are demonstrated

Rib Anatomy 13

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Typical Ribs  Head  Neck  Tubercle  Angle  Shaft  Subcostal

Groove Typical rib. The features (A) and midbody cross section (B) of a typical rib are demonstrated

Rib Anatomy

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Atypical Ribs #1-short, flat (S-I), wide, Supports Subclavian vessels  #1, 10-12 articulate with only = # vertebra  #11, 12 don’t articulate with transverse processes, or anteriorly at all 

Atypical ribs. The 1st (A) and 12th (B) ribs are shown.

Joints of Thoracic Wall 15

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Although movements of the joints of the thoracic wall are frequent e.g., during respiration, the range of movement at the individual joints is small. Any disturbance that reduces the mobility of these joints interferes with respiration. Joints of the thoracic wall occur between the:       

Vertebrae (intervertebral joints). Ribs and vertebrae (costovertebral joints: joints of the heads of ribs and the costotransverse joints). Sternum and costal cartilages (sternocostal joints). Sternum and clavicle (sternoclavicular joints). Ribs and costal cartilages (costochondral joints). Costal cartilages (interchondral joints). Parts of the sternum (manubriosternal and xiphisternal joints) in young people; usually the manubriosternal joint and sometimes the

Typical Rib Articulation 

Dorsal (P) Attachment Thoracic Vertebrae  Head of Rib  2 costal facets  



Superior costal facet Inferior costal facet of vertebra above it Intervertebral disc

 Tubercle

of Rib  Transverse Costal Facet  e.g. Rib #4 articulates with Superior Costal Facet and Transverse Costal Facet of T4 & Inferior Costal Facet of T3 16  Ventral (A) Attachment to

Typical Rib Articulation 17

Costovertebral joints. The elements of the joint of the head of the rib and the costotransverse joint are identified.

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Muscles of the Thoracic Wall 

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Except a small area posteriorly, the thorax is entirely covered by muscle. These muscles can be grouped into two groups. Muscles on the Outside of the Thorax, 

most of which are inserted to the upper limb and include:          

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Pectoralis major Serratus anterior Pectoralis minor Trapezius Rectus abdominis Latissimus dorsi External oblique Rhomboids Internal oblique Serrati posterior

Muscles of the Thoracic Wall Proper – 

that are attached to the vertebrae (muscles of the back), the ribs and the sternum (intercostal muscles).

The Intercostal Muscles 19

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The intercostal muscles fill the intercostal spaces together with the intercostal vessels, nerves and membranes. Their fibers attach the ribs above and below each space and assist in respiration. They appear in the following three layers. External layer - formed by the external intercostal muscle  Middle layer - formed by the internal intercostal muscle  Internal layer - formed by intercostalis intimi (inner most intercostal),subcostalis and transverse 

Intercostal Muscles 20

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External Intercostals  O:

Inferior border of rib above I: Superior border of rib below  Fibers run OBLIQUE (down and forward)  Aid in Inspiration (lift ribcage, increase dimensions) 

Internal Intercostals  O:

Superior border of rib below I: Inferior border of rib above  Fibers run at RIGHT ANGLES to external intercostals  Aid in forced expiration (depress ribcage, decrease dimensions) 

Intercostal Muscles 21

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All the intercostal muscles are innervated by the ventral rami of the spinal nerves that form the intercostal nerves. The intercostal spaces near the sternum and the vertebrae are not completely filled by muscles, vessels or nerves. The filling of the spaces near the sternum is completed by external (anterior) intercostal membrane, while the internal (posterior) intercostal membrane completes that of those near the

Intercostal Muscles 22

Diaphragm 

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Origin: 1. Sternal head: from xiphoid process. 2. Costal head: lower six ribs and costal cartilage. 3. Vertebral head: right and left crura from the first, second and third lumbar vertebrae and arcuate ligaments. Insertion: Central tendon of the diaphragm. Nerve Supply: Motor: phrenic nerve. Sensory: phrenic and Intercostal nerves. Action: Increase the vertebral diameter of the

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Muscles of Thorax

Muscle

Origin

Insertion

Action

Pectoralis major

Sternum, Ribs 2-6

Pectoralis minor

Ribs 3-5

Serratus anterior (ventralis)

Ribs 1-9

Greater Adduct, tubercle of Flex, Med humerus Rotate Arm Coracoid Depress, process of Rotate scapula scapula Scapula Protract, Rotate scapula

Innervation M&L pectorals

M&L pectorals Long Thoracic

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Muscles of Thorax

Muscle Trapezius

Origin Ligamentum nuchae, C7-T12

Insertion Clavicle, Spine of scapula

Levator Scapulae

C1-C4

Medial border of scapula Medial border of

Rhomboids C7-T5

Action Elevate, Adduct, Rotate, Depress Elevate scapula

Innervation Accessory

Adduct, Elevate,

D. Scapular

D. Scapular

Muscles of Thorax 27

Muscle Deltoids

Origin Insertion Clavicle, Deltoid Scapula tuberosity of humerus Latissimus Iliac Interdorsi crest, tubercular groove of T7-12, Lumbar humerus fascia

Action Flex, Abduct, Extend, Lat & med. rotate arm Extend, Adduct, Med. rotate arm

Innervation Axillary

Thoracodorsal

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Rotator Cuff Muscles

Muscle

Origin

Insertion

Action

Supraspinatu s

Supraspinous fossa of scapula Infraspinous fossa of scapula Lateral border of scapula

Greater tubercle of humerus Greater tubercle of humerus Greater tubercle of humerus Lesser tubercle of humerus

Abduction of arm

Innervatio n Suprascapul ar

Lat rotation of arm

Suprascapul ar

Lat rotation of arm

Axillary

Med rotation of arm

Subscapular

Infraspinatus Teres Minor

Subscapularis Subscapular fossa of scapula

Nerves and Vessels (Neurovascular bundle) of the thoracic wall

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The main nerve and vascular supplies to the thoracic wall run in the intercostal spaces in bundles that form the neurovascular bundle of the thoracic wall. Each bundle consists of vein, artery and nerve, which are related to the lower borders of the ribs, where they lie In the costal grooves and protected by their sharp lower edges. The components of the bundle are arranqed from cranial to caudal in the order of VAN, i.e. Vein, Artery, and Nerve. To avoid the injury of this

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Neurovascular bundle of the thoracic wall

The Intercostal Nerves 31

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There are 12 pairs of intercostal nerves. Each intercostal nerve is divided into  

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The posterior branches 

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anterior (ventral) and posterior (dorsal) branches or rami. supply the muscles, bones, joints and skin of the back.

The anterior branches  

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run segmentally in the intercostal spaces as intercostal nerves. At the level of the midaxillary line, they give lateral cutaneous branches to the skin of the lateral thoracic wall. Near the edge of the sternum, anterior cutaneous branches are given off to the anterior thoracic wall

The Intercostal Nerves 32

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The intercostal nerves innervate all the muscles along their way.  carry sensory fibers not only from the skin of thorax but also from the abdominal wall, breast, parietal pleura and parietal peritoneum.  They also carry postganglionic sympathetic fibers to blood vessels, sweat glands, arrectores pillorum muscle.  The anterior branch of the 12th spinal nerve runs below the costal margin, and hence called subcostal nerve. 

The Intercostal Nerves 33

Dermatomes and myotomes of the trunk. Note the relationship between the area of skin (dermatome) and skeletal muscle (myotome) innervated by a spinal nerve or segment of the spinal cord.The dermatomes of the thorax (T1 to12) are shown at the right.

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Intercostal Arteries   

There are two sets of intercostal arteries: 

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the posterior intercostal arteries  

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Allarise from the thoracic aorta, except the first two, the first two arise from the intercostalis suprema (supreme intercostal) artery, a branch of branch of costocervical trunk originating from the subclavian artery.

anterior intercostal arteries  

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anterior and posterior intercostal arteries.

The upper six are branches of the internal thoracic, while the lower five are branches of the musculophrenic artery, a branch of the internal thoracic artery running along the lower border of the thorax.

The thoracic wall gets additional arterial supply by some branches of the axillary artery.

Intercostal Arteries 35

Intercostal Veins & Lymphatic Drainage 36 

Intercostal Veins  

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Similar to the arteries there are posterior and anterior intercostal veins. The posterior intercostal veins drain into the brachiocephalic, azygos (right side), hemiazygos and accessory hemiazygos (left side) that ultimately drain into the superior vena cava. The anterior intercostal veins drain into musculophrenic and internal thoracic veins that finally end in the brachiocephalic vein.

Lymphatic Drainage of the Thoracic Wall  

Superficial and deep lymphatic vessels drain the lymph from the thoracic wall. Anterior thoracic wall  

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Superficial vessels - drain into anterior axillary lymph nodes Deep vessels - drain into internal thoracic (parasternal) lymph nodes

Posterior thoracic wall  

Superficial vessels - drain into the posterior axillary lymph nodes Deep vessels - drain into the intercostal lymph nodes

Intercostal Veins 37

Thoracic Apertures 38

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The thoracic cavity communicates with the neck and upper limb through the superior thoracic aperture, the anatomical thoracic inlet  Structures entering and leaving the thoracic cavity through this aperture include the trachea, esophagus, vessels, and nerves.  The adult superior thoracic aperture measures approximately 6.5 cm anteroposteriorly and 11 cm transversely.  Because of the obliquity of the 1st pair of ribs, the superior thoracic aperture slopes anteroinferiorly.  The superior thoracic aperture is bounded: 

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Posteriorly by the T1 vertebra. Laterally by the 1st pair of ribs and their costal cartilages.

Thoracic Apertures 39

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The thoracic cavity communicates with the abdomen  

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through the inferior thoracic aperture, the anatomical thoracic outlet In closing the inferior thoracic aperture, the diaphragm separates the thoracic and abdominal cavities almost completely. The inferior thoracic aperture is more spacious than the superior thoracic aperture. Structures passing to or from the thorax to the abdomen pass through openings in the diaphragm (e.g., the inferior vena cava and esophagus) or posterior to it (e.g., aorta). The inferior thoracic aperture is bounded:   

Posteriorly, by the T12 vertebra. Posterolaterally, by the 11th and 12th pairs of ribs. Anterolaterally, by the joined costal cartilages of ribs 7 to10, forming the costal margin.

The Breast 40

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Location: (female breast) Superior border: 2nd rib  Inferior border: 6th rib  Medial border: Sternum  Lateral border: Midaxillary line 

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Location: (male nipple) 

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Fourth Intercostal Space, Midclavicular line

Underlying muscle Pectoralis major and minor  Part of serratus anterior, external obliques 

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Lateral Thoracic Artery, branches of Internal Thoracic A., Post. Intercostals Intercostal, Internal Thoracic, Axillary Veins Branches of Intercostal Nerve

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Mammary Glands Lactiferous (modified sweat) Glands Breast made of 15-25 lobes (each a compound alveolar gland)

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Lobes made of lobules (= clusters of acini/alveoli) Acini/Alveoli lined w/milk-secreting simple epithelial cells Lactiferous Ducts of lobes open at nipple Areola-ring of pigmented skin around nipple  Sebaceous

gland produce sebum during nursing

Surface Anatomy 42

Use the next 3 slides and follow the book to palpate (feel) the features listed

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Anterior Surface of Thorax 

Palpate the following  Sternum

(3 parts)  Jugular notch  Sternal Angle (= 2nd rib)  Clavicle  Costal margin  Xiphosternal joint  

Midclavicular Line Midaxillary Line

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Anterior Surface of Thorax 45

Anterior Surface of Thorax 46

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Posterior Surface of Thorax Palpate the following  Spinous

Process of C7  Scapula (ribs 2-7)  Scapular

spine  Acromion Process  Inferior Angle of Spine  Inferior Border  Read

about breast & diaphragm

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Locating Internal Structures Pleural Cavities  Inferior

margin = adjacent to T12 in Posterior Midline  To Rib 10 at Midaxillary line  To Rib 8 at Midclavicular line  To Xiphosternal joint medially  Lungs posterior border is 2 ribs superior to pleural cavity (rib 8) 

Heart  Deep

to xiphisternal angle

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Vertebral Column Humans’ made of 26 bones

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 Cervical

7  Thoracic 12  Lumbar 5  Sacrum (5 fused sacral vertebrae)  Coccyx (4 fused coccygeal vertebrae)  

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Extends from skull to pelvis Supports body, muscle attachment Vertebral Canal  Created

by vertebral foramen  Contains + protects spinal cord  Intervertebral foramina Pg 45, 18

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 

  

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Cervical Vertebrae (7)

**Transverse Foramen ** Superior Articular Facets face superoposteriorly Inferior Articular Facets face inferoanteriorly Allows wide range of motion Spinous process fairly short, bifid (except for C7) Vertebral Foramen is Triangular Body is wider laterally than in A-P direction

Page 31

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Atypical Cervical Vertebrae 

C1 – Atlas  No

body  No Spinous Process  Superior Articular facets are kidney shaped 

C2 – Axis  Odontoid

Process =

Dens  Other features typical Page 32

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Thoracic Vertebrae (12) **Transverse Costal 

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Pg 119

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Facets ** *S/I Costal facets on vertebral body* Spinous Processes long, point inferiorly Superior Articular Facets face Dorsally/Posteriorly Inferior Articular Facets face Ventrally/Anteriorly Vertebral Foramen is Circular

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   

Lumbar Vertebrae (5) Spinous process is short, rectangular, projects dorsally Superior Articular Facets face Medially Inferior Articular Facets face Laterally Vertebral Foramen is Triangular Body is large and Kidney-shaped

Page 30

Sacrum & Coccyx 54

Sacrum 

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5 fused Sacral Vertebrae Articulates with  5th Lumbar vertebra  Coccyx  Ilia of coxal bones Functions in weight transfer Has a body, sacral canal, sacral foramina Remnants of other typical vertebrae features visible

Coccyx  3-4 fused Coccygeal vertebrae  Articulations  #1 articulates with 5th Sacral Vertebra  Some muscle + ligament attachment  Slightly different orientation in males vs. females  No canal

Intervertebral Discs 55

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Absent between  C1

and C2  Sacrum and coccyx 

Annulus Fibrosus  Outer

collar of concentric rings  Outer rings = ligaments  Inner rings = fibrocartilage  Supportive/Structural 

Nucleus Pulposus  Inner

disc, cushiony pad  Remnants of notocord  Shock Absorber

Pg 41

Vertebral Column

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IN 

OUT

IN Page 45

OUT

Lateral Curvature (Following Dorsal Side)  Cervical Region = Concave curve  Thoracic Region = Convex curve  Lumbar Region = Concave curve  Sacrum = Convex curve

Abnormal Curves

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Scoliosis-abnormal lateral curve of more than 10° 

 www.nlm.nih.gov

Kyphosisexaggerated thoracic curve 

 www.nlm.nih.gov

“twisted disease”

“humped disease”

Lordosis-accentuated lumbar curve

Ligaments of Vertebral Column

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Anterior Longitudinal Ligaments (neck – sacrum) 

 

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Posterior Longitudinal Ligaments (neck – sacrum) 

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Run vertically on anterior surface of vertebral bodies + intervertebral discs Wide,strong Prevents hyperextension

Run vertically on posterior surface of intervertebral discs only Narrow, weak Prevents hyperflexion

Page 44 Ligamentum Flavum (contains elastic connective