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[Type text] Anatomy Practical and Lecture Structure List [Type text] Mastoid process- absent or rudimentary in neonate skull; forms postnatally as SCM pulls on it Superior nuchal line- SCM and trapezius attach to it Styloid Process- Stylohyoid lig., stylomandibular lig., stylohyoid m., and stylopharyngeous m. attach to it Hyoid bone- only distantly articulated to other bones by muscles or ligaments. Provides attachment to the muscles of the floor of the mouth and the tongue above, the larynx below, and the epiglottis and pharynx behind. o Hyoid is ossified from six centers: two for the body and one for each cornu. Commences in the greater cornua toward the end of fetal life, body shortly after, and lesser cornua during the first or second year after birth. Middle age before fibrous connection between the body and greater cornu ossifies. o Muscle attachments: Superior: middle pharyngeal constrictor muscle, hyoglossus, digastric, stylohyoid, geniohyoid, mylohyoid Inferior: thyrohyoid, omohyoid, sternohyoid o Body- second pharyngeal arch gives rise to superior part, while cartilage of third pharyngeal arch forms the lower portion o Greater Horn- projects backward from body; connect to the lateral hyothyroid lig.; hyoglossus, constrictor, and digastric and stylohyoid muscles Cartilage of the third pharyngeal arch o Lesser Horn- stylohyoid lig. Attaches Derived from 2nd pharyngeal arch Platysmao Insertion- base of mandible o Artery- branches of submental and suprascapular o Nerve- Cervical branch of CN VII o Actions- Draws mouth downward, and draws skin of neck up when teeth are clenched Sternocleidomastoid (SCM) o Origin- Medial portion of clavicle o Insertion- Mastoid process and superior nuchal line o Artery- Occipital and superior thyroid o Nerve- motor- accessory nerve; sensory- cervical plexus o Actions- rotationa and flexion unilaterally; forced inspiration assist bilaterally Stylohyoid o Origin- styloid process o Insertion- greater cornu of hyoid o Nerve- CN VII o Action- elevates the hyoid during swallowing Mylohyoid o Origin- mylohyoid line of mandible [Type text] Anatomy Practical and Lecture Structure List [Type text] o Insertion- body of hyoid bone and median raphe o Artery- mylohyoid branch of inferior alveolar o Nerve- mylohyoid nerve from inferior alveolar branch of V3 o Action- elevates hyoid and tongue; depresses mandible Digastric o Anterior belly Origin- digastric fossa (mandible) Insertion- intermediate tendon on hyoid Artery- submental branch of VII Nerve- V3 via mylohyoid nerve Action- Opens jaw when masseter and temporalis are relaxed o Posterior Belly Origin- mastoid process Insertion- intermediate tendon Artery- occipital artery Nerve- CN VII o Intermediate tendon- perforates the stylohyoid muscle and is held in position by a loop of fibrous tissue between body and greater horn of hyoid Sternohyoid o Origin- manubrium of sternum o Insertion- hyoid o Artery- superior thyroid o Nerve- C1-C3 by branch of ansa cervicalis o Action- depresses hyoid Omohyoid o Inferior Belly Originates at upper border of the scapula o Superior Belly Lower border of the body of the hyoid lateral to the insertion of sternohyoid o Nerve- ansa cervicalis (C1-C3) o Action- depresses the larynx and hyoid bone; also carries hyoid backward and to the side Sternothyroid o Origin- manubrium o Insertion- thyroid cartilage o Artery- superior thyroid o Nerve- ansa cervicalis o Action- depresses thyroid cartilage Thyrohyoid o Origin- thyroid cartilage of larynx o Insertion- hyoid bone o Artery- superior thyroid o Nerve- C1 via hypoglossal [Type text] Anatomy Practical and Lecture Structure List [Type text] o Actions- elevates thyroid, and depresses hyoid bone Common Carotid artery- lies within the carotid sheath; bifurcates at level of C4 into ICA and ECA o Lies within the carotid triangle- Border muscles are SCM, stylohyoid and posterior belly of digastric above, and superior belly of omohyoid below o It commonly gives off no branches prior to bifurcation External Carotid Artery o Superior thyroid- Originates at anterior border of SCM and runs upward in the carotid triangle If artery is severed but not ligated during a thyroidectomy, it will bleed profusely o Ascending pharyngeal- one of the arteries that supplies the pharynx (smallest branch of ECA) o Lingual- arises from ECA between the superior thyroid artery and the facial artery Runs toward greater cornu of hyoid, curves downward forming a loop and passes beneath the digastric and stylohyoid, runs beneath the hyoglossus, then to the tongue on its lower surface o Facial artery- Arises in carotid triangle and lies on middle pharyngeal constrictor o Occipital artery- arises opposite the facial a.; supplies blood to back of scalp and sterno-mastoid muscles o Posterior auricular a.- arises from ECA above digastric and stylohyoid; ascends beneath parotid gland and between the cartilage of the ear and mastoid process (supplies blood to scalp post. to the ear and ear) Carotid sinus- place where atherosclerotic plaques form very often; where numerous baroreceptors are located; baroreceptors are innervated by CN IX Carotid body- small cluster of chemoreceptors located at the bifurcation of the carotid artery; detects changes in PO2 and PCO2; also sensitive to temp. and pH Internal Carotid Artery- supplies the brain Subclavian a- arises from aortic arch on the left and brachocephalic artery on the right- supplies left and right arms respectively Subclavian vein- joins with internal jugular vein and drains into brachiocephalic vein- forming the venous angle External Jugular vein- receives greater part of the blood from the exterior of the head and deep parts of the face; used for venous access when no peripheral vein is available in hospital settings; drains into the subclavian vein lateral to the junction of the subclavian vein and the internal jugular vein Internal jugular vein- collecting blood from the brain, superficial parts of face, and neck; superficial and susceptible to damage which can lead to lots of blood loss and hypovolaemic shock and death if not treated. Cuts or [Type text] Anatomy Practical and Lecture Structure List [Type text] abrasions in the skin near the jugular vein will bleed longer and more profusely (shaving)- since 95% of the body’s blood passes through this vein, it takes on average about 30 minutes to fully stop a shaving abrasion on the face. Cervical Plexus- C1-C4: it anastomoses with the accessory and hypoglossal nerves and sympathetic; has cutaneous branches and muscular branchesansa cervicalis, phrenic, and segmental branches Ansa cervicalis- loop of nerves that are part of the cervical plexus and lies superficial to the internal jugular vein in the carotid triangle; branches innervate most of the infrahyoid muscles (sternothyroid, sternohyoid, and omohyoid) o Superior root- formed from C1 of the cervical plexus; goes around the occipital artery and descends on the carotid sheath; branches sent to superior belly of the omohyoid and upper parts of sterothyroid and sternohyoid o Inferior Root- formed from fibers of C2 and C3; branches to the inferior belly of omohyoid and lower parts of sternothyroid and sternohyoid Phrenic nerve- C3-C5 and passes down between lung and heart to reach the diaphragm; important for breathing (passes motor to diaphragm and receives sensory from it); in the thorax it supplies mediastinal pleura and pericardium Hypoglossal nerve- innervates muscles of the tongue; General somatic efferent (GSE); innervates genioglossus, hyoglossus, and styloglossus muscles; can be transected to help connect to the facial nerve when it is damaged so facial muscles work again but can cause some tongue weakness Vagus nerve- right gives rise to recurrent laryngeal nerve that hooks around the right subclavian artery- forms posterior vagal trunk at the lower part of the esophagus and enters the diaphragm through the esophageal hiatus; left vagus nerve enters the thorax between left common carotid artery and left subclavian artery and descends on the aortic arch- gives rise to left recurrent laryngeal nerve that hooks around the aortic arch to the left of the ligamentum arteriosum. Sympathetic chain- T1-L2; forms a plexus on the internal carotid artery Superior cervical ganglion- only ganglion in the sympathetic nervous system that innervates the head and neck (largest and most rostral of the three cervical ganglia) Gray ramus communicans- from the adjacent paravertebral ganglion of the sympathetic trunk and contains both preganglionic and postganglionic nerve fibers of the sympathetic nervous system Other things to know o Investing deep fascia- encloses SCM and Trapezius o Prevertebral fascia- encloses vertebral region of neck o Pretracheal fascia- encloses visceral region of neck o Carotid sheath- encloses the vascular region of the neck [Type text] Anatomy Practical and Lecture Structure List [Type text] o Thyroid cartilage- from 4th and 6th branchial arch Lamina- 2 of them that fuse on the anterior side of the cartilage to form a peak called the laryngeal prominence o Submandibular gland-develops later than the parotid gland; superficial and deep lobes are separated by the mylohyoid muscle; receives blood supply from facial and lingual arteries Naris- nostril Nasal septum- composed of perpendicular plate of ethmoid bone, vomer bone, cartilage of the septum, crest of the maxillary bone, and crest of the palatine bone; o Artery- anterior ethmoidal, posterior ethmoidal, sphenopalatine, greater palatine, and branch of superior labia o Nerve- anterior ethmoidal nasopalatine nerves Hard palate o Artery- greater palatine artery o Nerve- greater palatine nerve and nasopalatine nerve o Incisive canal- descending palatine artery and nasopalatine nerve go through this Sphenoethmoidal recess- small space in the nasal cavity that lies posterior and superior to the superior concha into which the sphenoidal sinus opens o Ostium of the sphenoidal sinus Superior concha- part of the ethmoid bone; connected to the middle turbinates by nerve-endings and serve to protect the olfactory bulb o Superior meatus- lies between the superior concha and middle concha; the sphenopalatine foramen opens into it behind and the posterior ethmoidal cells in front Ostia of the ethmoidal air cells Middle concha- project downward over the openings of the maxillary and anterior and middle ethmoid sinuses, and act as buffers to protect the sinuses from coming into contact with direct air o Middle meatus- nasal opening or canal situated between the middle and inferior conchae Ethmoidal bulla- caused by a bulging of the ethmoidal cells which open on or immediately above it o Ostia of ethmoidal air cells Hiatus semilunaris- crescent- shaped groove in the lateral wall of the nasal cavity just inferior to the ethmoidal bulla Ostium of frontal sinus Ostia of ethmoidal air cells Ostium of nasolacrimal duct Inferior concha- largest of the turbinates; responsible for the majority of airflow direction, humidification, heating, and filtering of air inhaled through the nose o Inferior meatus- largest of the 3 meatuses; space between the inferior concha and the floor of the nasal cavity [Type text] Anatomy Practical and Lecture Structure List [Type text] Ostium of the nasolacrimal duct Concha are made of pseudostratified columnar, ciliated respiratory epithelium with a thick, vascular, and erectile glandular tissue layer Frontal sinus- situated behind the brow ridges; opens into the anterior part of the corresponding middle nasal meatus through the frontonasal duct ; absent at birth o Artery- supra-orbital and anterior ethmoidal o Nerve- supraorbital nerve Maxillary sinus- largest of the paranasal sinuses and drains into the middle meatus of the nose; sinusitis; present at birth as air cells and develops through childhood o Artery- infraorbital artery and posterior superior alveolar artery o Nerve- posterior superior alveolar nerve, middle superior alveolar nerve, anterior superior alveolar nerve and infraorbital nerve Sphenoidal sinus- present as very small cavities at birth, but main development takes place after puberty; potential complication is cavernous sinus thrombosis o Nerve- posterior ethmoidal nerves, postganglionic parasympathetic fibers of the facial nerve Ethmoidal air cells- numerous thin-walled cavities situated in the ethmoidal labyrinth o Nerve- anterior and posterior ethmoidal nerves and orbital branches of pterygopalatine ganglion Mucoperiosteum (all sinuses)- compound structures consisting of mucous membrane and periosteum; includes epithelium and lamina propria Nasopalatine nerve- branch of pterygopalatine ganglion (V2) Sphenopalatine artery- branch of the maxillary artery; artery responsible for most serious posterior nosebleeds (epistaxis) Nasal mucosa- produces the mucus in the nose Mental symphysis- faint ridge on median line of mandible; origin for the geniohyoid and genioglossus muscles Genial tubercles- inferior and superior mental spines o Inferior- origin of geniohyoid and suprahyoid muscles o Superior- origin of genioglossus muscle Mylohyoid line- line on the inside of the mandible ; mylohyoid muscle originates from the anterior part of the line Lingual frenulum- small fold of mucous membrane extending from the floor of the mouth to the midline of the underside of the tongue Sublingual foldLingual tonsil- rounded masses of lymphatic tissue that cover the posterior region of the tongue Palatoglossus muscle o Origin- palatine aponeurosis o Insertion- tongue o Nerve- vagus (via pharyngeal branch to pharyngeal plexus [Type text] Anatomy Practical and Lecture Structure List [Type text] o Action- raising the back part of the tongue Styloglossus muscle- shortest and smallest of the 2 styloid muscles o Origin- styloid process o Insertion- tip and sides of tongue o Nerve- hypoglossal nerve o Action- retraction and elevation of the tongue Hyoglossus muscleo Origin- hyoid o Insertion- side of the tongue o Nerve- hypoglossal nerve o Action- depresses and retracts the tongue Genioglossus muscle- relaxation of this muscle can be implicated in obstructive sleep apnea o origin- superior part of the mental spine of the mandible o insertion- dorsum of the tongue and body of the hyoid o artery- lingual artery o nerve- hypoglossal o action- inferior protrude the tongue, middle depress, superior draw the tip back and down Geniohyoid o Origin- inferior mental spine o Insertion- hyoid o Nerve- C1 via the hypoglossal nerve o Action- carry hyoid bone and tongue upward during deglutition Orbicularis oris o Origin- maxilla and mandible o Insertion- skin around the lips o Artery- inferior labial artery and superior labial artery o Nerve- CN VII- buccal branch o Action- puckers the lips Buccinator o Origin- alveolar processes of the maxillary bone, mandible and TMJ o Insertion- fibers of the orbicularis oris o Artery- buccal artery o Nerve- buccal branch of CN VII o Actions- chewing, sucking, and holding food in Hypoglossal nerve- CN XII Lingual nerve- branch of V3 which supplies sensory innervation to the tongue and also carries fibers from the facial nerve that return taste info from the anterior two thirds of the tongue Submandibular ganglion- one of the 4 parasympathetic ganglia of the head and neck; innervates submandibular and sublingual glands Lingual vein- begins at underside of tongue and drains to the internal jugular vein Parotid duct- route that the saliva takes from the parotid gland [Type text] Anatomy Practical and Lecture Structure List [Type text] Sublingual glando Artery- sublingual artery (branch of lingual artery of ECA) o Nerve- submandibular ganglion Submandibular duct- drains submandibular and sublingual glands o Where spray of salivary fluid comes from preparing to take first bite “gleeking” Gingiva- gums (soft tissue lining the mouth) Oral mucosa- mucous membrane lining the inside of the mouth Longus collio Origin- transverse processes of C5-T3 o Insertion- anterior arch or the atlas o Artery- ascending pharyngeal and vertebral arteries o Nerve- C2-C6 o Action- flexes the neck and head Longus capitis o Origin- anterior tubercles of the transverse processes of 3, 4, 5, and 6 cervical vertebra o Insertion- basilar part of the occipital bone o Nerve- C1-C3/C4 o Action- flexion of the neck at the atlanto-occipital joint Rectus Capitis anterior muscleo Origin- atlas o Insertion- basilar part of the occipital bone o Artery- ascending artery o Nerve- ventral primary rami of spinal nerves C1-2 o Action- flexion of the neck at the atlanto-occipital joint Rectus capitis lateralis o Origin- upper surface of the transverse process of the atlas o Insertion- under surface of the jugular process of the occipital bone o Nerve- C1, C2 o Action- lateral flexion Pharyngeal venous plexus- plexus of veins on the outer surface of the pharynx that ends in the internal jugular vein Superior thyroid artery- arises from the ECA just below the level of the greater cornu of the hyoid bone and ends in the thyroid gland Superior laryngeal artery- source is the superior thyroid artery and pierces the hyothyroid membrane and supplies larynx Vertebral artery- arises from the subclavian arteries and enter deep to the transverse process of C6 Pharyngeal muscles o Superior constrictor Origin- medial pterygoid plate, pterygomandibular raphe, alveolar Insertion- pharyngeal raphe, pharyngeal tubercle [Type text] Anatomy Practical and Lecture Structure List Artery- ascending pharyngeal artery and tonsillar branch of facial artery Nerve- pharyngeal plexus of vagus nerve Action- swallowing o Middle constrictor Origin- hyoid bone Insertion- pharyngeal raphe Ascending pharyngeal artery Pharyngeal plexus of vagus nerve Action- swallowing o Inferior constrictor Origin- cricoid and thyroid cartilage Insertion- pharyngeal raphe Nerve- pharyngeal plexus of vagus nerve o Stylopharyngeus 3rd pharyngeal arch Origin- styloid process Insertion- thyroid cartilage Nerve- glossopharyngeal nerve Action- elevate the larynx and pharynx and swallowing o Palatopharyngeus Origin- palatine aponeurosis and hard palate Insertion- upper border of thyroid cartilage Artery- facial artery Nerve- pharyngeal branch of vagus nerve Action- pulls pharynx and larynx upward o Salpingopharyngeus Origin- lower part of the cartilage of the auditory tube Insertion- fibers pass down and blend with the palatopharyngeus muscle to the upper border of the thyroid cartilage Nerve- vagus Action- assists in elevating the pharynx and pulls on the torus tubarius to pressure equalize the middle ear Superior laryngeal nerve- branch of the vagus nerve and receives a branch from the superior cervical ganglion of the sympathetic; palsy of this nerve causes change in pitch of the voice and inability to make explosive sounds due to paralysis of the cricothyroid muscle; bilateral palsy- tiring and hoarse voice (injured during thyrectomy); 4th pharyngeal arch Recurrent laryngeal nerve- branch of the vagus nerve and supplies all the intrinsic muscles of the larynx with exception of the cricothyroid muscles; also innervates the posterior cricoarytenoid muscles; 6th pharyngeal arch; injury to the nerve can result in hoarseness or loss of voice (especially during thyroid and parathyroid surgery) Glossopharyngeal nerve- innervates the stylopharyngeus; general sensory fibers from tonsils, pharynx, and posterior 1/3 of tongue; special sensory [Type text] [Type text] Anatomy Practical and Lecture Structure List [Type text] (taste) from posterior 1/3 of tongue; visceral sensory fibers from carotid bodies and sinus; supplies parasympathetic to parotid gland; if severed, will cause loss of bitter and sour taste and impaired swallowing Cricoid cartilage- only complete ring of cartilage around the trachea; when intubating during general anesthesia, the cricoid cartilage is compressed to compress the esophagus to prevent gastric reflux; cartilage used to locate placement of emergent endotracheal intubation o Lamina o arch Epiglottis- flap made of elastic cartilage tissue covered with a mucous membrane and attached to the entrance of the larynx; 4th pharyngeal arch; functions to protect the glottis during eating and drinking o Epiglottic cartilageArytenoid cartilage- aid in vocal cord movement: tensed, relaxed, or approximated; 4th and 6th branchial arches Cricothyroid joint- joints connecting the cricoid and thyroid cartilages; aids in changing of pitch of voice Cricoarytenoid joint- joint connecting the cricoid and arytenoid cartilages Cricothyroid muscle o Origin- anterior and lateral cricoid cartilage o Insertion- inferior cornu and lamina of the thyroid cartilage o Nerve- external laryngeal branch of vagus o Action- tension and elongation of the vocal folds Posterior cricoarytenoid muscle o Origin- posterior part of the cricoid o Insertion- muscular process of the arytenoid cartilage o Nerve- recurrent laryngeal branch of the vagus o Action- abducts and laterally rotates the cartilage pulling the vocal ligaments away from the midline, opening the rima glottidis Lateral cricoarytenoid muscle o Origin- lateral part of the arch of the cricoid o Insertion- muscular process of the arytenoid cartilage o Nerve- recurrent laryngeal branch of the vagus o Action- adduct and medially rotate the cartilage pulling the vocal ligaments towards the midline and backwards, closing the rima glottidis Arytenoid muscle o Origin- arytenoid cartilage on one side o Insertion- arytenoid cartilage on the other side o Artery- superior laryngeal artery o Nerve- recurrent laryngeal branch of the vagus o Action- approximate the arytenoid cartilages (close the rima glottis) Thyroarytenoid muscle o Origin- inner surface of thyroid cartilage (anterior aspect) o Insertion- anterior surface of arytenoid cartilage [Type text] Anatomy Practical and Lecture Structure List [Type text] o Nerve- recurrent laryngeal branch of the vagus o Action- helps reduce tension on the vocal folds during speech to decrease pitch Vocalis muscle o SAME AS THYROARYTENOID? Median cricothyroid ligament- anterior part of the cricothyroid ligament; connects thyroid and cricoid cartilages Aryepiglottic fold- triangular opening at the entrance of the larynx that is bound by the epiglottis and arytenoid cartilages and mucous membrane; used in phonation for a growling sound Vestibular fold- “false vocal cord”; play a large role in keeping food and drink out of the airway, breathing, and phonation; used to produce a deep sonorous tone in phonation; formed by the vestibular ligament extending from lateral walls of epiglottis to arytenoid cartilage covered with mucous membrane Vestibule- portion of the cavity of the larynx above the vocal folds; Vocal fold- upper free margin of conus elasticus which is covered by mucous mucous membrane o Vocal ligament- enclosed within the vocal folds; composed of intermediate and deep layer of lamina propria Glottis-“rima glottides”; vocal folds and the opening between them; Piriform recess- bounded medially by the aryepiglottic fold, laterally by the thyroid cartilage and thyrohyoid membrane; common place for food to be trapped; recurrent laryngeal nerve as well as internal laryngeal nerve are deep to this recess Inferior laryngeal nerve- terminal branch of the recurrent laryngeal nerve Superior thyroid artery- arises from ECA just below the level of the greater cornu of the hyoid and ends in the thyroid gland; must be ligated at the thyroid when conducting a thyroidectomy Superior laryngeal artery- branches from the superior thyroid artery near its bifurcation from the ECA and pierces the hythyroid membrane, and supplies the muscles, mucous membrane, and glands of the larynx, anastomosing with the branch from the opposite side Inferior thyroid artery- arises from the thyrocervical trunk and passes upward, in front of the vertebral artery and longus colli muscle and turns medially behind the carotid sheath and its contents and also behind the sympathetic trunk, the middle cervical ganglion resting upon the vessel; as it reaches the lower border of the thyroid gland it divides into two branches, which supply the postero-inferior parts of the gland, and anastomose with the superior thyroid artery; relationship with RLN is highly variable so it can be damaged during surgery Inferior laryngeal artery- ascends on the trachea to the back part of the larynx under cover of the inferior constrictor in company with the RLN and supplies the muscles and mucous membrane of this part Lung fissures [Type text] Anatomy Practical and Lecture Structure List [Type text] o Oblique o Horizontal (right only) Lung Lobes o Superior o Lingula (left only)- part of the superior lobe o Inferior o Middle (Right only) Primary bronchus- left and right branch from the trachea; *right is larger, so things tend to get stuck there more often Secondary bronchus- “lobar bronchi” arise from the primary bronchi with each one serving as the airway to a specific lobe of the lung; 3 in right lung and 2 in left lung Tertiary bronchus- “segmental bronchi” arise from the secondary bronchi; each of these serves a specific bronchopulmonary segment o Bronchopulmonary segment- 10 in right lung and 8 in left lung; each have their own artery, thus each bronchopulmonary segment is supplied by a segmental bronchus and two arteries, a pulmonary artery and a bronchial artery which run together through the center of the segment; veins and lymphatic drain along the edges; each segment is a discrete anatomical and functional unit and so each can be surgically removed without affecting the function of the other segments Pulmonary artery- carries deoxygenated blood from the heart to the lungs; begins at the base of the right ventricle and branches into two pulmonary arteries (right and left); pulmonary hypertension and pulmonary embolism are relevant clinically to this artery; embryology precursor is the truncus arteriosus o Secondary branch o Tertiary branch Pulmonary Vein- large blood vessel that receives oxygenated blood from the lungs and drains into the left atrium of the heart; 4 in total (2 from each lung); drains to the left atrium; sometimes the pulmonary veins drain into the systemic circulation in whole or in part; this is clinically a problem o Superior pulmonary vein o Inferior pulmonary veinBronchial artery- supplies nutrition and oxygenated blood to the lungs; usually there are 2 that run to the left lung and one to the right lung; left bronchial arteries usually arise directly from the thoracic aorta; right can arise from a few different locations; clinical relevance- typically enlarged and tortuous in chronic pulmonary thromboembolic hypertension, usually not reconnected following lung transplantation; aneurysms of the bronchial artery may mimic aortic aneurysms Cartilage rings of trachea- vary from 16-20 in number; each forming a semicircular ring of hyaline cartilage which occupies the anterior two-thirds or so of the circumference of the trachea [Type text] Anatomy Practical and Lecture Structure List [Type text] Trachealis muscle- smooth muscle that bridges the gap between the free ends of the c-shaped cartilages at the posterior border of the trachea ad o Nerve- vagus and upper thoracic spinal nerves o Action- constricts the trachea Carina- in line with the angle of Louis; lies to the left of midline and is responsible for the bifurcation of trachea to right and left primary bronchi Pleura o Parietal pleura- innervated by intercostal nerves and phrenic Costal pleura- portion that lines the inner surfaces of the ribs and intercostals Diaphragmatic pleura- lines the convex surface of the diaphragm Mediastinal pleura- applied to the other thoracic viscera Cervical pleura- “pleural cupola” rises into the neck over the apex of the lung o Visceral pleura- attached directly to the lungs; derived from mesoderm; nerve- pulmonary plexus Pleural cavity- space between parietal and visceral pleura o Costomediastinal recess- potential space at the border of the mediastinal pleura and the costal pleura; helps lungs to expand during deep inspiration o Costodiaphragmatic recess- potential space in the pleural cavity at junction of costal and diaphragmatic pleura; lungs expand into this space during forced inspiration; *pleural effusions collect here when standing; thoracocentesis is performed here Hilus of the lung- structures from root of lung enter and leave Bronchopulmonary lymph node Pulmonary ligament- the parietal pleura surrounding the root of the lung extends downward beyond the root of the lung as a fold called the pulmonary ligament; retains the inferior part of the lung in position Thoraco-abdominal diaphragm- (thoracic diaphragm) o Artery- pericardiacophrenic artery; musculophrenic artery; inferior phrenic arteries o Vein- superior phrenic vein, inferior phrenic vein o Nerve- phrenic and lower intercostal nerves o Embryological precursor- septum transversum, pleuroperitoneal folds o Central tendon- thin but strong aponeurosis situated near the center of the vault formed by the muscle, but somewhat closer to the front than to the back of the thorax so that the posterior muscular fibers are longer o Caval opening- T8 (IVC and right phrenic nerve) o Esophageal hiatus- T10 (esophagus and ant. And post. vagal trunks) o Aortic hiatus- T12 (aorta, azygos vein, hemiazygos vein, and thoracic duct