anatomy presentation ho10(thorax 1)
TRANSCRIPT
The Thorax 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 required.
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Thoracic Wall
The thoracic wall consists of skin, fascia, nerves, vessels, muscles,
and bones. The functions of the thoracic wall
include 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 breasts are in the subcutaneous tissue overlying the pectoral muscles covering the anterolateral thoracic wall.
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Skin of the Thorax
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 related.
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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
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Fascia of the Thorax
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
a part of the superficial fascia of the body containing the breast, which is fibrous and tough
Deep layer 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 (Sibson's fascia) and the part related to the diaphragmatic pleura is called phrenicopleural fascia.
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Skeleton of Thoracic Wall
The thoracic skeleton forms the osteocartilaginous thoracic cage
The thoracic skeleton (bony thorax) includes 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 intercostal spaces, which are occupied by intercostal muscles, vessels, and nerves.
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Skeleton of Thoracic Wall
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The Bony Thorax
Sternum Manubrium, Body
(Gladiolus), Xiphoid Process
Ribs 7 True Ribs 5 False Ribs
Clavicle Scapula Vertebrae
Cervical,Thoracic, Lumbar, Sacral (Sacrum), Coccygeal (Coccyx)
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Projections and Depressions
Site of muscle and ligament attachments Spine Process
Help form joints Head Facet
Allow BV, nerves, and muscles to pass Notch Fossa
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Thoracic Cage Borders:
Thoracic vertebrae posteriorly
Ribs laterally Sternum and
costal cartilages anteriorly
Forms protective cage around heart, lungs, and other organs
Composed of: Sternum Ribs Vertebrae
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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
time Partial attachment of
many muscles
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The Ribs 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 # 2-9
Atypical Ribs Ribs #1, 10, 11, 12
Reinforce thoracic cage
Typical rib. The features (A) and midbody cross section (B) of a typical rib are demonstrated
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Rib Anatomy
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
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Rib Anatomy
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.
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Joints of Thoracic Wall
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 xiphisternal joint are fused in the elderly.
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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
Ventral (A) Attachment to Sternum Via costal cartilage
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Typical Rib Articulation
Costovertebral joints. The elements of the joint of the headof the rib and the costotransverse joint are identified.
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Muscles of the Thoracic Wall 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: 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).
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The Intercostal Muscles
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 thoracis muscles.
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Intercostal Muscles
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) Innermost Intercostals, Subcostals, Transversus
thoracis Attachments similar to Internal Intercostals, Attach ribs Small, variable, function unclear
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Intercostal Muscles
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 vertebrae
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Intercostal Muscles22
DiaphragmDiaphragm 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
thoracic cavity (muscle of inspiration).
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
thoracic cavity (muscle of inspiration).
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Muscles of ThoraxMuscle Origin Insertion Action Innervation
Pectoralis major
Sternum, Ribs 2-6
Greater tubercle of humerus
Adduct, Flex, Med Rotate Arm
M & L pectorals
Pectoralis minor
Ribs 3-5 Coracoid process of scapula
Depress, Rotate scapula
M & L pectorals
Serratus anterior (ventralis)
Ribs 1-9 Scapula Protract, Rotate scapula
Long Thoracic
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Muscle Origin Insertion Action Innervation
Trapezius Ligamentum nuchae, C7-T12
Clavicle, Spine of scapula
Elevate, Adduct, Rotate, Depress
Accessory
Levator Scapulae
C1-C4 Medial border of scapula
Elevate scapula
D. Scapular
Rhomboids C7-T5 Medial border of scapula
Adduct, Elevate, Rotate
D. Scapular
Muscles of Thorax26
Muscles of Thorax
Muscle Origin Insertion Action Innervation
Deltoids Clavicle, Scapula
Deltoid tuberosity of humerus
Flex, Abduct, Extend, Lat & med. rotate arm
Axillary
Latissimus dorsi
Iliac crest,
T7-12, Lumbar fascia
Inter-tubercular groove of humerus
Extend, Adduct, Med. rotate arm
Thoraco-dorsal
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Rotator Cuff Muscles
Muscle Origin Insertion Action Innervation
Supraspinatus
Supraspinous fossa of scapula
Greater tubercle of humerus
Abduction of arm
Suprascapular
Infraspinatus Infraspinous fossa of scapula
Greater tubercle of humerus
Lat rotation of arm
Suprascapular
Teres Minor Lateral border of scapula
Greater tubercle of humerus
Lat rotation of arm
Axillary
Subscapularis Subscapular fossa of scapula
Lesser tubercle of humerus
Med rotation of arm
Subscapular
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Nerves and Vessels (Neurovascular bundle) of the thoracic wall
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 neurovascular bundle during thoracic tap (thoracentesis), needle must be inserted near the upper border of a rib (not near the lower border).
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Neurovascular bundle of the thoracic wall
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The Intercostal Nerves
There are 12 pairs of intercostal nerves. Each intercostal nerve is divided into
anterior (ventral) and posterior (dorsal) branches or rami.
The posterior branches supply the muscles, bones, joints and skin of the
back. The anterior branches
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
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The Intercostal Nerves
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.
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The Intercostal Nerves
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: anterior and posterior intercostal arteries.
the posterior intercostal arteries 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 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.
In addition to the thorax, the intercostal arteries supply the spinal cord, the breast and abdominal wall
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Intercostal Arteries35
Intercostal Veins & Lymphatic Drainage
Intercostal Veins 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
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
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Intercostal Veins37
Thoracic Apertures
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: Posteriorly by the T1 vertebra. Laterally by the 1st pair of ribs and their costal
cartilages. Anteriorly by the superior border of manubrium.
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Thoracic Apertures
The thoracic cavity communicates with the abdomen 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. Anteriorly, by the xiphisternal joint.
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The Breast
Location: (female breast) Superior border: 2nd rib Inferior border: 6th rib Medial border: Sternum Lateral border: Midaxillary line
Location: (male nipple) Fourth Intercostal Space, Midclavicular line
Underlying muscle Pectoralis major and minor Part of serratus anterior, external obliques
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) 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 Lobes separated by adipose tissue and suspended by
connective tissue = Suspensory Ligaments of the Breasts
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Surface Anatomy
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 Thorax45
Anterior Surface of Thorax46
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 Cervical 7 Thoracic 12 Lumbar 5 Sacrum (5 fused sacral vertebrae) Coccyx (4 fused coccygeal
vertebrae) Extends from skull to pelvis Supports body, muscle
attachment Vertebral Canal
Created by vertebral foramen Contains + protects spinal cord
Intervertebral foraminaPg 45, 18
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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
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Thoracic Vertebrae (12) **Transverse Costal
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 Body is Heart-shaped
Pg 119
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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
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Sacrum & Coccyx
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 Lateral & median sacral
crest
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
Sacrum Coccyx
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Intervertebral Discs 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
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Vertebral Column
Lateral Curvature (Following Dorsal Side) Cervical Region = Concave curve Thoracic Region = Convex curve Lumbar Region = Concave curve Sacrum = Convex curve
IN
IN
OUT
OUTPage 45
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Abnormal Curves
Scoliosis-abnormal lateral curve of more than 10° “twisted disease”
Kyphosis-exaggerated thoracic curve “humped disease”
Lordosis-accentuated lumbar curve “bent-backward disease”
www.nlm.nih.gov
www.nlm.nih.gov
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Ligaments of Vertebral Column
Anterior Longitudinal Ligaments (neck – sacrum) Run vertically on anterior surface of vertebral bodies +
intervertebral discs Wide,strong Prevents hyperextension
Posterior Longitudinal Ligaments (neck – sacrum) Run vertically on posterior surface of intervertebral discs only Narrow, weak Prevents hyperflexion
Ligamentum Flavum (contains elastic connective tissue) Attaches lamina of vertebrae (one on right, one on left) Very strong Page 44
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