Anatomy 1 Test 2 - Back PDF

# Anatomy 1 test 2- Back ## The Back * The region: posterior aspect of the neck, to the area just superior to the gluteal region * Contents * Vertebral column * Range: 7 cervical, 12 thoracic, 5 lumbar, 5 fused segments of the sacrum, 1 coccyx * Function: protects the spinal cord...

# Anatomy 1 test 2- Back ## The Back * The region: posterior aspect of the neck, to the area just superior to the gluteal region * Contents * Vertebral column * Range: 7 cervical, 12 thoracic, 5 lumbar, 5 fused segments of the sacrum, 1 coccyx * Function: protects the spinal cord. It serves as an attachment for the ribs. It provides support and place of attachment for the pectoral and pelvic girdle. * Overall arrangement: usually consists of 33 vertebrae, placed in series and connected by ligaments and intervertebral discs * Series of cervical/lumbar lordosis and thoracic/sacral kyphosis: rotating helps us resist gravity * Osteoporosis: smokers, in elderly ladies osteoporosis may be a cause of excessive kyphosis * Scoliosis: vertebral column is off to the side laterally * Structure of individual vertebrae * Vertebral body * Disc (cartilaginous structure that sits between vertebra and alleviates bone on bone stress) * Arch * Foramen-opening * Vertebral foramen: houses spinal cord * Intervertebral foramen: made up of two vertebrae and has exit space for the spinal nerve * Notches * Spinous process: posteriorly * A series of levers both for muscles of posture and for muscles of active movement * Transverse processes: transverse laterally * Provide sites to which back muscles and ligaments attach * Zygapophyseal joint/facet joint: * Arches of vertebrae articulate here at the vertebral bottom * Superior/inferior articular process come together to form the zygapophysial joint * Articular processes: projections of the vertebra that serve the purpose of fitting with an adjacent vertebra * Superior articular processes face medially and posteriorly * Inferior articular processes face laterally and anteriorly ## Regional characteristics ### Cervical vertebrae- C1-C7 * Atlas C1/axis C2 complex: unique features and functions * C1-atlas: articulation point for the skull- no spinous process, transverse ligament, transverse process with a foramen transversarium. * C2-axis has dense, that supports the axis as it rotates with the skull and serves as a pivot point for the skull * Articulations and movements of the skull/ stabilization and pivot point of the skull- the Axis C2 acts as a pivot for the rotation of the atlas and skull) * C3-C6, and C1 (has no spinous process) * C3-C5: * Foramen transversarium: serves as a process point for the vertebral artery * Bifid spinous process-in cervical column * C6-C7: * Progressively lengthening (as you go down the cervical column they lengthen) * C7-has the longest one.- We can feel it (bifid above and not including C6 and C7) ### Thoracic vertebrae- 12 vertebrae * Characteristic for heart-shaped vertebral bodies * Costal facets: (function)- they link up with the ribs- are responsible for side bending/ torso flexion, thorax protection by stabilizing ribs/rib support, and transferring weight. * Spinous processes: long and strong transverse and spinous processes- they are angled inferiorly for continuous protection of the spinal cord. ### Lumbar vertebrae- 5 * Large vertebral bodies: kidney shaped, support function * Vertebral bodies get larger as they travel more inferiorly=more weight bearing. * Transverse process=smaller and slender (long)- can twist/rotate/flex * Spinous process=shorter and flatter (sturdy) ### Fused sacrum- 5 * Fused unit with coccyx * Base of the sacrum is at the TOP- it serves to help transmit the weight to the lower extremities. It is wedged in and articulates with the hip bones * Stabilization of the pelvis * Transmit body weight to the pelvic girdle via sacroiliac joints (point of articulation between the fused sacrum and the two pelvic bones) ### Coccyx- 1 * Fused evolutionary remnant (tail) ## Vertebral joints * Intervertebral joints * Essential at serving same purpose as another joint at any other point of articulation between bones- aka decrease friction between joints, allow movement with complete range of motion * Lateral portion= Annulus fibrosus * In the center= nucleus pulposus * In between end of the bone on either side= epiphyseal rims (seals when fully grown) * (Spina bifida- vertebral arch does not form completely) * Anterior longitudinal ligament: large, very wide, strong, thicker- serves to stabilize the articulating vertebrae. Disks provide movement but the movement can be damaging and harmful if we don't have ‘hardware' to stabilize it. So it keeps the vertebral column from moving too much. It supports the vertebral column during movement. * Posterior longitudinal ligament: stabilizes vertebral column but not as much as the anterior longitudinal ligament (maybe because of shape/size) * (Herniated disk= usually ruptures/bulges posteriorly.) ## Spinal Cord * Arrangement is very similar to the brain- in regard to meninges- outer membrane of the spinal cord is similar to that of the brain (dura/arachnoid/pia.... CSF- subarachnoid) * anterior/ventral and posterior/dorsal segments of spinal nerves of spinal nerves- every vertebral segment is like another ‘floor’ * Spinal nerve is the cultivation of the dorsal (has ganglia) and vertebral routes * Dorsal root: afferent sensory fibers of spinal cord enter- ascend * Ventral root: efferent motor fibers descent and leave. * Applications regarding lumbar puncture * (Lumbar puncture- need to get needle between L2/L3 or sometimes L3/L4) * Epidural blocks: anesthetics can be administered in this function- pregnant woman -L3-L4 * Dermatomes: area of skin supplied by a single spinal root * Maps of the human body- c1, c2, c3,c4,c5- a reflection of the layout/ map of the spinal nerves responsible for sensation that is sent by different spinal nerves segments. * Definition- Area of skin supplied by a single spinal root- map of body * Application- shingles- reflection of a dermatome - aka it follows along a dermatome * The spinal cord itself- there are ascending and descending tracts (like an elevator) * Lateral horn: autonomic/sympathetic motor neurons that serve visceral organs (viscera=organs in chest, abdomen and pelvis) * Dorsal horn has NO cell bodies * Interneurons- another relay station/synapse * White matter: reflection of heavily myelinated nerve tracts * dorsal, ventral, and lateral funiculi or white columns * Ascending tracts=sensory * Dorsal column: * Precisely localized sensation of touch and vibration * Contralateral pathway- crosses over * Spinothalamic pathway: * Lateral and ventral divisions * Transmit impulses for pain and temperature. Not as precise localization (as the dorsal columns)- sometimes hard to localize pain due to this * Crosses over lower down * Spinocerebellar- dorsal and ventral divisions: * Convey information regarding muscle/tendon stretch to cerebellum * Generally ipsilateral * Descending tracts= motor * By nature divided into: * Upper motor neuron: link to brain. * Injury: spastic paralysis, positive babinski sign- reflex hammer on lateral side of foot, bit toe goes up (extension of big toe)- hypertonic, hyperflexia, flaccid fasciculations * Lower motor neuron: from spinal cord to effector (target)-hypotonic, negative babinski sign * Injury: flaccid paralysis * Corticospinal tract: * Lateral ventral side * Produce voluntary movement on the opposite side of the body from the cerebral hemisphere that it originates from * Tectospinal tract: * Turns neck to turn to follow moving objects * Vestibulospinal tract: * Activates ipsilateral trunk/head muscles maintaining balance * Reticulospinal tract: * Visceral muscle control ## Spinal Reflexes * Components of a reflex arc: * Receptor-Site of action (ex;pin going into skin) * Sensory neuron-Transmits afferent impulse to CNS (sensory neuron enters the spinal cord in the dorsal aspect and synapses in the interneuron integration center.) * Integration center-Interneuron- is the synapse between sensory/motor neurons- it is able to bypass the brain due to these interneurons. * Motor neuron- going to leave the ventral aspect of the spinal cord, going to act on an effector. * Effector- ie- a muscle pulling away from a hot stove * Example-Patellar knee jerk reflex- L2/L4 * effector= quadriceps femoris ## Spinal Cord Blood Supply * Much of the spinal cord blood supply branches off the aorta which comes off the heart and arches backward and travels down the thorax and abdomen... * Aorta-internal thoracic artery-intercostal artery-subgastric artery- heart- lungs- stomach (epigastric)- diaphragm (musculophrenic) * Spinal cord is supplied by branches of the vertebral, ascending cervical (more lateral), deep cervical, intercostal, lumbar, and lateral sacral arteries * Converge at: (1-single)Anterior spinal artery. and (2-single paired) posterior spinal artery formed by vertebral artery branches * Both run longitudinally length of the spinal cord- also contribute to blood supply * Ant/Post. Segmental medullary A.- come off of the anterior/posterior spinal artery- supplement blood supply to cervical/lumbar enlarged areas (increased O2 demand- maybe because it is more metabolically active) * Great anterior segmental medullary A. (Adamkiewicz)- supplements lumbosacral enlargement as well. Arises on left side at lower Thoracic/Upper Lumbar levels * Radicular A. branch off intercostal A.- * Supply roots of spinal nerves * Veins * Three anterior and three posterior spinal veins, ant/post medullary veins, radicular veins ## External (on outside-near bones/vertebra)/Internal (deep) vertebral plexus distributed at length- run the entire length of the spinal cord (just like the veins) ## Parasympathetic/Sympathetic Division of the Spinal Cord ### Parasympathetic: * basal metabolic activity “Rest and digest” provided to viscera by CN III (ciliary ganglion), VII (pterygopalatine ganglion), X and IX (otic ganglion, submandibular ganglion) * Also S2-S4 * Called "Craniosacral division"- because it involves these cranial nerves 3,7,9,10 * Long pre ganglionic fibers (especially CN X) ### Sympathetic: * Heightened metabolic activity, organism under duress,“Fight or flight" response * Thoracic, upper lumbar segments * Longer post ganglionic fibers * Cervical ascending division-trunk on either side of spinal cord ## Muscles of the Back ### From superficial to deep muscles: #### Superficial extrinsic back M.M.- * Trapezius * Innervation: Cranial nerve XI * Action: Elevates, depresses, and retraction of scapula * Origin: Occipital bone, the ligamentum nuchae, and the spinous processes of T1-T12. * Insertion: Lateral third of the clavicle, as well as acromion and scapular spine of the scapula * Latissimus dorsi * Innervation: branch of the posterior cord of the brachial plexus (C6 to C8 with C7 predominant * Action: adduct, medially rotate, and extend the arm at the glenohumeral joint * Origin: Spinous processes of thoracic T7-T12, thoracic lumbar fascia, iliac crest and inferior 3 or 4 ribs, inferior angle of scapula. * Insertion: on floor of intertubercular groove of the tubercle * Levator scapulae * Innervation: cervical nerve (C3-C4) and dorsal scapular * Action: elevate the scapula and tilt the glenoid cavity inferiorly by rotating the scapula downward * Origin:transverse processes of the first four cervical vertebrae * insertion: superior angle and medial border of scapula, between the superior angle and base of the spine of scapula. * Rhomboid's maj/min (a little deeper but still superficial) * Innervation: Scapular rhomboids- both Rhomboids innervated from dorsal scapular nerves.. * Action: scapular retraction around the scapulothoracic joint. * Origin: spinous processes of the T2-T5 vertebra * Insertion: scapula's medial border near the base of the spine of the scapula. #### Intermediate extrinsic back M.Μ- * Serratus posterior inferior/superior- innervated by anterior rami * Proprioceptive and respiratory in function; innerv/act/O/I #### Superficial layer of intrinsic back M.M.- * Splenius capitis * Origin: arises from ligamentum nuchae and the spinous processes of te C7-T6 vertebrae * Insertion: into the mastoid process of the temporal bone and the lateral third of the superior nuchal line of the occipital bone. * Action: Extend the head and neck. Laterally bend the head and neck to te side of the contraction. * Innervation: Dorsal Rami of the middle cervical spinal nerves. * Cervicis- innervated by posterior rami, act/O/I * Origin: * Insertion:arises from ligamentum nuchae and the spinous processes of te C7-T6 vertebrae * Action: Extend the head and neck, they laterally bend the head and neck to the side of contraction. * Innervation: Dorsal rami of the lower cervical spinal nerves. ***MOST BACK MUSCLES ARE INNERVATED BY POSTERIOR RAMI BESIDES SERRATUS.*** #### Intermediate layer of intrinsic back M.Μ.: * Iliocostalis thoracis * Longissimus thoracis * Spinalis thoracis #### Deep intrinsic back muscles- * Semispinalis-Thoracis/Cervicis/Capitis. * Multifidus * Rotatores- brevis, longus #### Minor deep layer of intrinsic back M.M. * Interspinales-sit between spinous processes * Intertransversarii- in between the disk * Levatores costarum- elevate the ribs * Proprioception- the deeper you go the more they are involved ### Muscles of the Thorax #### Muscles of the pectoral region | Muscle | Origin | Insertion | Innervation | Function | |---|---|---|---|---| | Pectoralis major | Medial half of clavicle and anterior surface of the sternum, first seven costal cartilages, aponeurosis of external oblique | Lateral lip of intertubercular sulcus of humerus | Medial and lateral pectoral nerves | Adduction, medial rotation, and flexion of the humerus at the shoulder joint | | Pectoralis minor | Anterior surface of the third, fourth, and fifth ribs, and deep fascia overlying the related intercostal spaces | Coracoid process of the scapula | Medial pectoral nerves | Depresses tip of the shoulder; protracts the scapula | | Subclavius | Rib I at junction between rib and costal cartilage | Groove on inferior surface of middle third of clavicle | Nerve to subclavius | Pulls clavicle medially to stabilize sternoclavicular joint; depresses tip of the shoulder | * Muscles of the thorax: * Pectoralis major (runs deep to pec major), pectoralis minor, subclavius (sliver under the clavicle) * External and internal (deep) intercostals (they have different direction/grains), they run between the ribs, transversus thoracis, subcostal * Serratus posterior sup/inf * Movement of the thorax during respiration * The diaphragm and ventilation, thoracic movements * Inspiration-increase intrathoracic diameter/vol. * Press change draws air into lungs-inhalation * Passive expiration- * Diaphragm (floor of the thorax), intercostal, and other muscles relax, decrease intrathoracic volume, and increase intrathoracic pressure * Lung recoils and expels most of the air * Intra abdominal pressure decreases and it decompress the abdominal viscera * Passive Inspiration- * volume increases, pressure decreases * Forced inspiration/expiration- * Expiration * The vertical dimension of the central portion of diaphragm increases during forced inspiration * Diaphragm descends as it contracts compressing abdominal viscera * Vertical dimension returns to neutral during forced expiration, thorax also narrows, abdominal viscera decompressed * Opposite occurs during inspiration * Thorax also widens during forced inspiration * Rib movements during these processes: * Anterior/post view illustrate "bucket handle” movements * Lateral view illustrate “pendulum” movements * Anterior ramus: * turns into intercostal nerve as it travels * Nerves of the thoracic wall- 12 thoracic spinal nerves * Anterior rami T1-11 form intercostal nerves * Anterior rami of T12- Form subcostal nerves * Posterior rami: * Travel posteriorly to supply skin, Muscle of the back, and bone of the back * Thoracic region: * Typical intercostal nerves T3-6, their travels, branches and functions along the way- run along posterior aspects of the intercostal spaces between the parietal pleura and the internal intercostal membrane * Atypical intercostal nerves- T1-2, T7-11-inferior margins of the costal grooves * Dermatomes: * Map of the body in corresponding to what spinal cord segment is providing sensation to that particular area * Some overlapping of these, evolutionary significance- so if damage to one segment, may still have some sensing in that area (pain will tell important info- need to lift hand from hot surface) * Motor fibers produce muscular equivalent- Myotome * Rami communicantes: * Sympathetic chain- right and left ganglia- rami communications contribute to this ganglia * White- branch off the anterior ramus and travel to sympathetic ganglia "Preganglionic” fiber, then it synapses and >>> * Gray- Leaves sympathetic ganglion, rejoins anterior ramus and then travels to (target around the body) blood vessels, glandular tissue, sweat glands, smooth muscle of body wall/limbs “Postganglionic” * Vasculature of thoracic wall * Arteries derived from the thoracic aorta: * Posterior intercostal arteries and subcostal artery= (last one) * Brachiocephalic trunk off the ascending aorta(RIGHT SIDE): gives rise to the: Subclavian artery (laterally)- (then turns into axillary artery) * This gives rise: * Internal thoracic artery- inferiorly * Costocervical trunk-superiorly. * aorta-right : brachiocephalic trunk-subclavian artery- axillary artery- internal thoracic (inferiorly) costocervical trunk (superiorly). The internal thoracic- anterior intercostal artery-superior epigastric- musculophrenic artery * Internal thoracic artery: * gives rise to anterior intercostal artery * continues to run inferiorly and becomes the superior epigastric artery (near diaphragm) * Before it does this, it gives rise to a musculophrenic artery- from the junction of the internal thoracic artery and the last anterior intercostal artery * Last branch-terminal end of the internal thoracic of the artery- musculophrenic artery * Veins run a similar path * Subclavian vein passes first rib, axillary vein, 2 brachiocephalic veins (not called a trunk), posterior intercostal veins are coming off of- the azygous vein- right side of thoracic wall (NOT INFERIOR VENA CAVA), anterior intercostal vein coming off the internal thoracic vein * Superior vena cava- Azygos (right side) and hemi-azygos veins (left side) LAB- then to inferior vena cava ### Viscera of thoracic cavity * 3 compartments of thoracic cavity * Lungs within the pulmonary cavity * Each lung is enclosed by a pleural sac * Each sac is made of two membranes: * Visceral pleura- covers the lungs (green in pic) * Parietal pleura- lines the thoracic wall, mediastinum and diaphragm (purple/blue) * The potential space between these two: * Pleural cavity- not that big (if it was there would be a problem. )contains a capillary layer of serous fluid. The fluid lubricates the pleural surfaces and it allows the layers to slide smoothly over each other during respiration. It allows the lung tissue to move Surface tension from this layer- surface tension between the two layers- it is very important as it keeps the lung surface in contact with the thoracic wall. It reduces friction caused by movement. * issue with premature babies- don't have enough lung surfactant/protein- don't have proper amount of surface tension.. Cant breath well on their own because of this- give them steroids to help their lungs * Lungs- respiratory Organs,move air and exchange of CO2/O2 exchange * Light, spongy, elastic, capable of recoiling to 1/3 of their size * Right lung- horizontal and oblique fissure- divides the lung into 3 lobes- superior, middle, and inferior lobes. Left lung oblique only * Right lung larger but shorter/wider than left lung * It is shorter because the large visceral organ= liver sits in the right upper quadrant, pushes up against it- compresses it. * Left lung- has cardiac notch to accommodate for heart orientation * Has a lingua- tip of cardiac notch, * Apex- on top by the superior thoracic aperture, base- down by diaphragm * Hilum-opening area in each lung where vessels/bronchi enter * (Also lymphatics/nerves going through it) * Root- composed of the structures entering lung at the hilum: * Structures entering: Pulmonary A., sup/inf pulmonary veins, R/L main bronchus- entering the hilum * Trachea- origin and course * C shaped ring of hyaline cart * When you look at it anteriorly you see the cartilage/smooth muscle posteriorly- very close to the esophagus located posteriorly to the trachea * Trachea is lined with ciliated respiratory epithelium and goblet cells interspersed- designed to catch particulate matter and encapsulate with mucus- prevent matter from coming deep into the airway. * Goblet- secrete mucus * Cillia- catch particulate matter * Smooth M.M. arrangement on posterior border * Point of branching of trachea into right and left primary bronchi- carina * Right bronchi- shorter, wider, runs more vertically * Left bronchi- longer, more narrow, runs more horizontal * Important in PEDS: children like to put small objects in their nose- aspirate them. - most likely to hear decreased breath sounds on the lower left side- it is more likely for it to get stuck there. * Known as the bronchial tree * Inferiorly- bronchial tree breaks into segments: * Each primary bronchi will branch into secondary (lobar) bronchi * Lobar bronchi will branch into tertiary (segmental) bronchi, 3 on right, 2 on left * Segmental bronchi supply a bronchopulmonary segment * They feed the different lung segments * before antibiotics, this was how they isolated/encapsulate lung infections and keep the remaining lung intact... * Beyond segmental bronchi- 20-25 branches that end in terminal bronchioles * Terminal bronchioles give rise to several generations of respiratory bronchioles * Respiratory bronchioles provide 2-11 alveolar ducts * Alveolar ducts drain into alveolar sacs (5-6)- look like grapes- * Alveolar sacs are the end of the airway and the basic units of gaseous exchange in the lung * The payload of blood is brought to the sacs by the vasculature system- alveolar tracts are very thin surface membranes. * Arterial and venous capillaries are incontact with alveolar tracts- * Co2 out and O2 in * Lung vasculature- * Venous blood brought back to the heart- right atria- right ventricle- pulmonary trunk- right and left pulmonary arteries-lobar arteries- segmental arteries * Begins with pulmonary trunk branching off the right ventricle * This shortly branches into right and left pulmonary arteries * These branch into lobar arteries * Right lobar A. branches before it enters hilum (he's not sure if this is impt lol) * Lobar a goes to each lobe * These branch further into the segmental arteries * These ultimately in part form the alveolar capillary plexus where gaseous exchange occurs: * Co2 from metabolic waste is dissipated, here is the only place you can find oxygenous rich blood in venous system * Pulmonary venous system then begins as the capillaries drain into the intersegmental veins * These will drain into sup/inf pulmonary veins- on both R and L sided * Both sides all converge and return blood to the left atrium of the heart * Bronchial arteries- Supply blood to supporting lung tissue * Lung tissue itself need oxygen rich blood- bronchial arteries is what delivers it * Left branches off the thoracic aorta * right varies in origin: * May come off of: * Superior posterior intercostal A. * Left superior(inferior) bronchial A. * Common trunk with thoracic aorta with right 3rd posterior intercostal A. * Lung innervation- The anatomic and functional relationship of parasym/sym innervation * Parasympathetic and sympathetic innervations serving different functions * CN X- vagus N. coming off base of the the brain and has long preganglionic fiber and short postganglionic fiber- it contributes to the formation of the pulmonary plexus * Hoarseness- can be cancerous * Parasympathetic: serve Bronchoconstriction and vasodilation * Sympathetic- short pregang, long post from symp gang to lung serve to brochodilate and vasoconstrict * Sympathetic: short preganglionic, long post ganglionic fibers * Convergence point between sympathetic (vasodilate and dilate) and parasympathetic * Saga of sympathetic and parasympathetic relationship in regard to the lungs Pressure relationships in thoracic cavity-vasoconstrict * Atm-a constant measured as a stp- 760mm Hg (mercury) * Intrapulmonary pressure- air pressure in the lungs within the alveoli * Rises/falls with respiration but always equalizes with atmospheric pressure * Intrapleural pressure- air pressure in pleural cavity * Also fluctuates but always stays some 4mm Hg LESS than intrapulmonary pressure * If this intrapleural pressure equalizes or gets greater pressure that intrapulmonary: * Atelectasis-lung collapse, plugged bronchiole, alveoli filled with air then collapse and can't hold or expel the air. * Pneumothorax air entering lung can also collapsed lung, stab wounds, gun wounds ### Muscles of the thoracic wall | Muscle | Origin | Insertion | Innervatio n | Function | |---|---|---|---|---| | External intercostal | Inferior margin of the rib above | Superior margin of the rib below | Intercostal nerves; T1-T11 | Most active during inspiration; supports intercostal space; moves ribs superiorly | | Internal intercostal | Lateral edge of the costal groove of rib above | Superior margin of rib below deep to the attachment of the related external intercostal | Intercostal nerves; T1-T11 | Most active during expiration; supports intercostal space; moves ribs inferiorly | | Innermost intercostal | Medial edge of costal groove of rib above | Internal surface (near angle) of lower ribs | Intercostal nerves; T1-T11 | Acts with internal intercostal muscle | | Subcostales | Internal surface of lower ribs | Internal surface of second or third rib below | Related intercostal nerves | May depress ribs | | Transversus thoracis | Inferior margins and internal surfaces of costal cartilages of second to sixth ribs | Inferior aspect of surface of body of sternum, xiphoid process, and costal cartilages of ribs IV-VII | Related intercostal nerves | Depresses costal cartilages | ### Intrinsic back muscles (involved in proprioception and respiration) | Muscle | Origin | Insertion | Innervation | Function | |---|---|---|---|---| | Serratus posterior superior | Lower portion of ligamentum nuchae, spinous processes of CVII to TII, and supraspinous ligaments | Upper border of ribs II to V just lateral to their angles | Anterior rami of upper thoracic nerves (T2 to T5) | Elevates ribs II to V | | Serratus posterior inferior | Spinous processes of TXI to LII and supraspinous ligaments | Lower border of ribs IX to XII just lateral to their angles | Anterior rami of lower thoracic nerves (T9 to T12) | Depresses ribs IX to XII and may prevent lower ribs from being elevated when the diaphragm contracts |