Exam 3 Thorax Flashcards
Boundaries of the thorax
anterior: sternum, costal cartilage
posterior: 12 thoracic vertebrae, posterior part of 12 ribs, intercostal muscles
laterally: ribs, intercostal muscles
superior: first rib
inferior: diaphragm
level of the plane passing through sternal angle
T4-5 disc
superior thoracic aperture
- bordered by 1st rib
- opening for structures that enter/leave thoracic cavity that run to head, neck, UE
inferior thoracic aperture
- covered by diaphragm
- holes for structures entering the abdomen from the thorax
manubrium
- upper part of sternum
- clavicular notch: medial end of clavicle
- costal notch: costal cartilage of 1st rib
sternal angle
- between manubrium and superior body of sternum
- same level as disc T4-5
- costal notch for cartilage of 2nd rib
body of sternum
-costal notches for cartilage of ribs 3-6
xiphisternal joint
- between inferior body of sternum and xiphoid process
- costal notch for cartilage of rib 7
True ribs
- ribs 1-7
- attach directly to sternum
false ribs
- ribs 8-12 (lower 5)
- costal cartilage of ribs 8,9,10 attach to rib above
- floating ribs = ribs 11, 12 (no costal cartilage, do not attach to sternum)
Ribs 3-10
- anterior costal notch (costal cartilage)
- head: interarticular crest (disc), two demifacets (superior/inferior vertebrae)
- rib 10 only has one facet, no interarticular crest
- neck: between costal tubercle and head
- body: costal tubercle to anterior costal notch
- rounded superiorly, sharp inferiorly - angle: sharp curvature beyond tubercle
- external surface: rough for iliocostalis attachment
- internal surface: COSTAL GROOVE (intercostal nerves, vessels)
- costal tubercle: attaches to TP
1st rib
- very short/curved
- head: one articular facet for T1
- scalene tubercle: superior surface, attachment for anterior scalene
- groove for subclavian v: medial to scalene tubercle
- groove for subclavian A: lateral to scalene tubercle
- inferior trunk of brachial plexus: passes posterior to scalene tubercle
- subclavian A,V, inferior trunk cross SUPERIOR THORACIC APERTURE to reach 1st rib*
Thoracic outlet syndrome
- tight scalene ant/med elevate 1st rib–>compress subclavian A,V, inferior trunk
- weakness in hypothenar, interosseous muscles
- tingling in ulnar side of hand
- pain in anterior chest, shoulder
- diminished pulse in involved limb
2nd rib
- longer, more rounded, less curved than 1st rib
- one articular facet for T2 vertebra
- scalene posterior: attached to tuberosity on superior surface, mid body
Ribs 11, 12
- shorter, less curved than other ribs
- one articular surface for vertebrae T11, 12
- no prominent costal tubercle
- ends covered in hyaline cartilage, no costal notch
Extrinsic muscles of thorax (attach to rib cage and other structures)
- iliocostalis
- longissimus
- pec major
- pec minor
- serratus anterior
- subclavius
- external oblique
- internal oblique
- transverse abdominis
- rectus abdominis
- levator costarum
scalenus anterior
nerve: C5-8 O:ant tubercle of TP C3-6 I: scalene tubercle, ridge of 1st rib -attaches anterior to subclavian A. A: elevate 1st rib, cervical flex (bilateral), rotation to opposite side (unilateral)
scalenus medius
N: C3-8
O: posterior tubercle of TP (C2), C3-7
I: superior 1st rib (posterior to groove for subclavian A)
-attaches posterior to subclavian A.
A: elevate 1st rib, cervical flex (bilateral), rotation to opposite side
Scalenus posterior
N: (C5),(C6),7,8
O:posterior tubercle of TP C4-6
I: outer posterior border of 2nd rib
A: elevate 2nd rib, cerv flex (bilateral), lateral flex (unilateral)
Intrinsic muscles of the thorax (attach only to rib cage)
- serratus posterior superior
- serratus posterior inferior
- external intercostals
- internal intercostals
- transversus thoracic
- innermost intercostal
- subcostal
external intercostals
N: intercostal nerve of that intercostal space
O: inferior body of rib above
-from costal tubercle to costal cartilage
-from cartilage junction to sternum (replaced by external intercostal membrane
I: superior body and costal cartilage of rib below
A: elevates rib below to expand A/P diameter of thorax during normal/forced inspiration; stabilizes bony thorax
internal intercostals
N: intercostal nerve of that intercostal space
O: inferior body of rib above
-from angle of rib to sternum (along costal groove)
-at angle of rib, muscle is replaced by internal intercostal membrane
I: superior body of rib below
-from angle of rib to sternum
-at angle of rib posteriorly, muscle replaced by internal intercostal membrane
-inferior attachment lies internal to external intercostal muscle
A: depresses rib above to reduce thoracic volume during forced expiration; may be active in forced inspiration; stabilizes bony thorax
transversus thoracis
N: intercostal nerve of that intercostal space
O: inferior body of sternum, xiphoid process; internal surface of costal cartilages 2-6
I: 4 to 5 slips of muscle attaching to inner surface of costal cartilages 2-6
A:depresses ribs during expiration
innermost intercostal
N: intercostal nerve of that intercostal space
O: internal surface of rib above (from angle of rib to costal cartilage)
I: internal surface of rib below (from angle of rib to costal cartilage)
A:depression of rib above–>decrease size of thoracic cavity during forced expiration; may be active in forced inspiration; stabilizes bony thorax
subcostal muscle
N: intercostal nerve of intercostal space
O: inner surface of angle of rib above
I: inner surface of angle of rib below or second rib below
A: elevate ribs–>inspiration
costovertebral joints
Head of rib w/ costal facets of vertebral bodies
- ribs 3-9 articulate w/ two vertebral bodies
- ribs 1 & 2 articulate w/ one vertebra each
- ribs 10-12 articulate w/ one vertebra each
Cover intervertebral disc
Synovial
ligaments of costovertebral joints
- radiate ligaments
2. intra-articular ligaments
costotransverse joint
- Tubercle of rib w/ TP
- synovial joint
ligaments of costotransverse joint
- superior costotransverse lig
- superior neck of rib below to inferior aspect TP above - lateral costotransverse lig
- tip of TP to adjacent costal tubercle - inferior costotransverse lig
- between posterior aspect of neck of rib –>anterior surface of TP
- between costovertebral/costotransverse joints
serratus posterior inferior
N: intercostal N of intercostal space (T9-11)
O: SP of T11-L2 or L3
I: lateral inferior margin of ribs 9-12
A: depresses lower ribs during ventilation; stabilizes costovertebral joints of ribs 9-12
*Intrinsic thoracic muscle
serratus posterior superior
N: intercostal N of intercostal space (T2-T4)
O:caudal part of ligamentum nuchae; SP C7-T3
I: ribs 2-4 or 5
A: elevates ribs during ventilation, stabilizes upper costovertebral joints of ribs 2-4
levator costarum
*extrinsic thoracic muscle
N:dorsal ramus of thoracic spinal nerve (intercostal) crossed by muscle
O: TP C7-T11
I: angle of rib below
-longus (skip one rib)
-brevi (attach to rib directly below)
A: ELEVATES RIBS (inspiration); thoracic extension (both sides), lateral flex (same side); thoracic rotation (opposite side)
intrinsic thoracic muscles that perform expiration (3)
- internal intercostals
- innermost intercostals
- transversus thoracic
intrinsic thoracic muscles that perform inspiration (3)
- external intercostals
- subcostal
- levator costarum EXTRINSIC THORACIC MUSCLE
muscles of inspiration (6)
- SCM
- scalenes
- external intercostals
- diaphragm
- subcostalis
- levator costarum
muscles of expiration (5)
- internal intercostals
- innermost intercostals
- transverse thoracis
- rectus abdominis
- transverse abdominis
location of intercostal N., A., V. relative to rib muscles
- subcostal groove
- between innermost/internal intercostals
intercostal N
- ventral rami T1-11
- runs w/ A. & V. along each rib
- motor to intercostal muscles
- sensory to skin of thoracic region
- Lateral Cutaneous N (lies external to external intercostals)
- sensory to skin
- divides into Ant/Post branches
- Intercostal N terminates near sternum as Anterior Cutaneous N
- Ant Cutaneous N divides into med/lat branches
Intercostal A branches from?
Intercostal V drains to?
Thoracic Aorta –> intercostal Arteries
intercostal V –>Azygos V (runs along anterior right side of vertebral column
Diaphragm innervation and action
Phrenic N (C3,4,5)–>keeps diaphragm ALIVE
O:
-sternal:xiphoid process
-costal: internal surface of lower six ribs, costal cartilages
-vertebral: upper 2-3 lumbar vertebrae (muscular crus, med/lat arcuate lig on each side); arcuate lig = extensions of T/L fascia
I:central tendon
A:
-lowers central tendon
-increases volume of thoracic cavity during inspiration
-decreases pressure on lungs–>allows inward movement of air
subcostal nerve
intercostal nerve of ventral ramus T12 (emerges below 12th rib)
anterior/posterior thoracic cavity expansion
true ribs (1-7)
medial/lateral thoracic cavity expansion
false ribs (8-12)
superior/inferior thoracic cavity expansion
diaphragm
4 openings of the diaphragm
- vena caval foramen (Between T8/9)
- inferior vena cava - esophageal hiatus (T10 vertebra)
- esophagus
- R/L vagal trunks - aortic hiatus (sides: R/L crus, ant: median arcuate lig, post: T12)
- aorta
- azygos V.
- thoracic duct - psoas gap (@ level of aortic hiatus, lateral to crura)
- psoas major, ilioinguinal N, genitofemoral N, sympathetic chain
costotransverse lig strained/torn during pregnancy
superior costotransverse lig
Anterior intercostal A.
- supplies anterior intercostal region
- Highest Thoracic A (1st part of Axillary A)–>1st,2nd intercostal space
- Internal Thoracic A (lateral edge of sternum, deep to transverse thoracis)–>2nd through 6th intercostal spaces
- Musculophrenic A (branch of Internal Thoracic)–> 7th-9th intercostal space & diaphragm
*Do not supply 10th/11th intercostal spaces
superior epigastric A
- branches off Internal Thoracic A @ 6th-7th intercostal space
- supplies diaphragm, upper rectus abdominals
posterior intercostal A
- supply 10th-11th intercostal spaces (no anterior intercostal A)
- Subclavian A–>costocervical trunk–>supreme intercostal A –> posterior intercostal A to 1st/2nd intercostal spaces
- Thoracic Aorta–>posterior intercostal A from 3rd-11th intercostal spaces
Anterior Intercostal V
- accompany corresponding arteries
- drain into musculophrenic V. & Internal Thoracic V.
posterior intercostal V
- Right: drain into azygos V.
- Left: drain into hemiazygos V., accessory hemiazygos V
- upper thorax: Hemiazygos V & Accessory Hemiazygos V drain into Azygos V
- Azygos V –> superior vena cava
Hiatal Hernia
- part of stomach slips through esophageal hiatus
- indigestion when supine–>need to be placed in inclined position
