Anatomy - CVR Flashcards
What allows optimal positioning of the head?
-Cervical spine is flexible
-Neck is slender
Why is the neck prone to injury?
The flexibility of the cervical spine
Why is the neck an extremely vulnerable area for injury?
Many vital structures packed into the small region with little protection
What 6 things does the neck contain?
-Respiratory tract structures
-GI tract structures
-Glands
-Arteries and veins
-Nerves
-Several groups of muscles
What structures of the respiratory tract are in the neck?
-Pharynx
-Larynx
-Trachea
What structures of the GI tract are in the neck?
-Pharynx
-Oesophagus
What glands are in the neck?
-Thyroid
-Parathyroid
What do nerves in the neck innervate?
-Serve head and neck
-Upper limbs
-Thoraco-abdominal viscera (via vagus)
-Diaphragm (phrenic)
What muscle groups are in the neck?
-Move head and neck
-Move larynx in speech
-Swallowing that form floor of mouth
-Platysma - very thin subcutaneous muscle deep to the skin of the neck
What muscle does this show?
-Platysma
-Very thin subcutaneous muscle deep to skin of the neck
How many cervical vertebrae are there?
Describe them:
-7 cervical vertebrae
-Small
-Articulate with each other at facet joints that are oriented obliquely
Describe the types of joints between cervical vertebrae:
-Facet joints
-Oblique (at an angle)
-Good range of flexion and extension of the cervical spine - in comparison to thoracic
What bone is situated anteriorly in the upper neck, inferior to mandible?
-Hyoid bone
-Helps to keep pharynx open
-Provides attachment point for several muscles in neck and tongue
Label this diagram:
What is it?
Hyoid bone
What bones and cartilage are in the neck?
-7 cervical vertebrae
-Hyoid bone
-Larynx
What composes the larynx and what is its function?
-Skeleton of small cartilages connected by membranes and small joints
-Protects airway
-Muscles attach to laryngeal cartilages to move them and move vocal chords (phonation)
In what terms is the neck described?
Anterior and posterior triangles
What separates the anterior and posterior triangles of the neck?
Sternocleidomastoid muscles
What does the sternocleidomastoid connect?
How does it act?
-Attached to:
-Sternum
-Clavicle
-Mastoid process (part of temporal bone)
-Can act:
-Bilaterally
-Unilaterally
What nerve innervates the sternocleidomastoid muscle?
The accessory nerve (CN XI)
What are the 3 boundaries of the anterior triangle of the neck?
-Anteriorly: Midline of neck
-Posteriorly: Anterior border of sternocleidomastoid
-Superiorly: Lower border of mandible
What bones and cartilaginous structures are in the anterior triangle of the neck?
-Trachea
-Larynx
What glands are in the anterior triangle of the neck?
-Thyroid
-Parathyroid
-Submandibular thyroid gland
What is this?
Where is it?
-Submandibular salivary gland
-Anterior triangle of the neck
What muscles are in the anterior triangle of the neck?
-Suprahyoid muscles:
-Connect hyoid to skull
-Form floor of mouth
-Move hyoid and larynx in speech and swallowing
-Infrahyoid muscles:
-Strap muscles
-Connect hyoid to sternum and scapula
-Move hyoid and larynx in speech and swallowing
What blood vessels are in the anterior triangle of the neck?
-Common carotid artery and its terminal branches - external and internal carotid arteries
-External carotid artery to the head and neck
-Internal jugular vein
What nerves are in the anterior triangle of the neck?
-Branches of facial nerve (CN VII)
-Glossopharyngeal nerve (CN IX)
-Vagus nerve (CN X)
-Accessory nerve (CN XI)
-Hypoglossal nerve (CN XII)
-Ansa cervicalis - fibres from C1-C3 which innervate infrahyoid muscles
What are the boundaries of the posterior triangle of the neck?
-Anteriorly: Posterior border sternocleidomastoid
-Posteriorly: Anterior border of trapezius
-Inferiorly: Clavicle
-Superiorly, apex is formed by sternocleidomastoid and trapezius
What muscles and vessels are in the posterior neck of the triangle?
-Muscles that move the head
-Part of subclavian artery and subclavian vein
-External jugular vein which drains scalp and face
What nerves are in the posterior triangle of the neck?
-Accessory nerve (CN XI)
-Roots of brachial plexus (spinal nerves supplying upper limb)
-Cervical plexus (fibres from C1-4)
-Phrenic nerve
Describe the suprahyoid muscles:
-4 paired muscles:
-Mylohyoid
-Geniohyoid
-Stylohyoid
-Digastric
-Superior to hyoid bone and form floor of the mouth
-When they contract, raise hyoid bone and larynx during speech and swallowing
Describe the infrahyoid muscles:
-4 paired ‘strap’ muscles:
-Sternohyoid
-Omohyoid
-Sternothyroid
-Thryohoid
-Inferior to hyoid bone and just lateral to the anterior midline of the neck
-Draw hyoid bone and larynx inferiorly during speech and swallowing
What do the sternohyoid and omohyoid connect and where do they lie?
-Lie superficially
-Attach hyoid to sternum
-Attach hyoid to scapula
What do the sternothyroid and thyrohyoid connect and where do they lie?
-Lie deep
-Attach sternum to thyroid cartilage
-Attach thyroid cartilage to hyoid
Where does the thyroid gland lie and what is it composed of?
-Right and left lobes
-Lie just lateral to the lower larynx and upper trachea
-Each lobe deep to sternothyroid muscle
What joins the right and left lobes of the thyroid gland?
-The isthmus
-Lies anterior to the trachea
What is the function of the thyroid gland and what regulates its function?
-Produces hormones which play important role in regulation of metabolic processes
-Pituitary gland regulates hormone secretion from the thyroid gland
What supplies blood to the thyroid gland?
Thyroid ima artery is an additional artery present in some people
What veins drain the thyroid gland?
What are the parathyroid glands?
-Four glands
-Right and left superior and inferior
-Located in posterior of thyroid gland
-Produce parathyroid hormone which plays a role in calcium regulation
-Supplied by inferior thyroid arteries
Where does the internal carotid artery branch in the neck?
-It doesn’t give off any branches in the neck
-Enters cranium and supplies brain
Where do the common carotid arteries run?
-Ascend in the right and left sides of the neck
-Bifurcate into external and internal carotid arteries
Where does the external carotid artery branch?
-Several branches in that supply head and neck
-Including:
-Pharynx
-Scalp
-Thyroid gland
-Tongue
-Face
Label this diagram:
What is at the bifurcation of the common carotid artery?
What is its significance?
-Carotid sinus - small swelling
-Baroreceptors constantly monitor arterial blood pressure
-Visceral sensory info relayed to CNS via glossopharyngeal nerve
-Results in reflex response that regulate blood pressure
What does the subclavian artery give rise to and what does it supply?
-Supplies upper limb
-Large branch, thyrocervical trunk
-This gives rise to inferior thyroid artery
What major vessels form the superior vena cava?
-Internal jugular vein is major vein in neck which drains blood from brain and part of face
-This unites with subclavian vein which returns blood from upper limb
-This forms braciocephalic vein
-Right and left brachiocephalic unite to form SVC
What smaller vessel runs in the neck and joins the subclavian vein?
External jugular vein
What nerve supplies the platysma in the neck?
Facial nerve (CN VII)
What does the glossopharyngeal nerve (CN IX) supply?
-Pharynx (sensory info)
-Carotid sinus (visceral sensory fibres that return to the CNS via CN IX)
What does the vagus nerve innervate in the neck?
-Vital for normal speech and swallowing
-Muscles of the pharynx (motor innervation)
-Larynx (motor and sensory info)
Where does the vagus nerve run in the neck?
-Between internal jugular vein and internal carotid artery (above bifurcation)
-Between internal jugular vein and common carotid artery (below its bifurcation)
-Three structures run together in fascial sleeve called carotid sheath
What does this show?
-Carotid sheath containing:
-Common carotid artery
-Internal jugular vein
-CN X - vagus
-Fascial sleeve
What does the accessory nerve (CN XI) innervate?
-Sternocleidomastoid
-Trapezius
What does the hypoglossal (CN XII) innervate?
-Motor to muscles of tongue
-Not supply any neck structures but travels through it
-Lateral to internal carotid artery and deep to external jugular vein
Where does the phrenic nerve form and what does it innervate?
-C3, 4, 5 nerve fibres
-Descends through neck to enter the thorax
-Innervates diaphragm
What is the head and neck richly innervated with?
-Sympathetic fibres nerves
-Sympathetic trunk extends as far as the base of the skull
What are the names of the associated sympathetic ganglia in the neck and what do they innervate?
-Superior cervical ganglia
-Middle cervical ganglia
-Inferior cervical ganglia
-Postganglionic fibres from these ganglia innervate the head and neck
What is the pharynx?
-Muscular tube which lies in the neck
-Forms part of the respiratory and GI systems
-One continuous passageway composed of 3 parts
What are the 3 parts of the pharynx and where are they located?
-Nasopharynx - posterior to nasal cavity
-Oropharynx - posterior to oral cavity
-Laryngopharynx - posterior to larynx
Label this diagram:
Describe the muscles of the pharynx:
-Outer layer of circular muscle
-Inner layer of longitudinal muscle
Label this diagram:
What does it show?
-External circular muscle layer is composed of three constrictor muscles
-Superior, middle and inferior constrictors that overlap each other
What is the action of the external circular muscles of the pharynx?
-Contract superior to inferior
-Swallowed food moves down the pharynx towards the oesophagus
Describe what happens during swallowing:
-Food in oral cavity pushed into oropharynx by tongue
-Soft palate rises and closes off nasopharynx from oropharynx
-Food enters laryngopharynx and constriction of pharyngeal wall move food into oesophagus
-Epiglottis closes off laryngeal inlet and prevents food or liquids from entering larynx
What is the innervation to the pharynx?
-Sensory fibres from glossopharyngeal nerve
-Motor fibres from vagus nerve
What nerves lie close to the posterior pharyngeal wall?
-Cervical part of sympathetic trunk and superior ganglion
-Superior laryngeal nerve
-Hypoglossal nerve - close to vagus
-Glossopharyngeal nerve - deep to carotid artery
Where does the superior laryngeal nerve run in proximity to the posterior pharyngeal wall?
-Branch of vagus
-Descends over posterior aspect of internal carotid artery
-Between inferior and middle constrictors of pharynx and larynx
What composes the larynx and what is its function?
-Several cartilages
-Membranes
-Small muscles
-Protects airway and contributes to phonation/speech
What are the 3 unpaired cartilages of the larynx?
-Epiglottis
-Thyroid
-Cricoid
Label the 3 unpaired cartilages of the larynx:
What are the 3 paired cartilages of the larynx?
-Arytenoid
-Cuneiform (very small)
-Corniculate (very small)
Label the 3 paired cartilages of the larynx:
How many cartilages compose the laryngeal skeleton:
-Nine
-Three unpaired
-Three pairs
Describe the structure of the thyroid cartilage:
-Composed of 2 flat cartilages (laminae) that meet in anterior midline
-This forms laryngeal prominence (Adam’s apple)
-Posterior laminae form superior and inferior projections called horns
What do the superior and inferior horns of the thyroid cartilage articulate with?
-Superior horns - attach to hyoid bone
-Inferior horns - articulate with cricoid below
Label this diagram:
What does it show?
Thyroid cartilage
What is this?
-Cricothyroid membrane
-Connects inferior border of thyroid and superior border of cricoid
-Pierced in an emergency airway
Describe the structure in green:
where is it attached?
-Epiglottis
-Attached to superior aspect of thyroid cartilage where two laminae meet
-During swallowing, epiglottis covers entrance to larynx (laryngeal inlet) and protects airway from entry of liquid or food
Describe the structures in blue:
-Arytenoid cartilages
-Sit on superior surface of cricoid cartilage
-Articulate with cricoid cartilage at small joint
-Small but vital for phonation
-Vocal cords attach to them and movements move the vocal cords
Label this diagram:
Label this diagram:
What two groups of muscles enact on the larynx?
Extrinsic and intrinsic
What are the extrinsic muscles of the larynx?
-Suprahyoid and infrahyoid muscles
-Do not move individual cartilages
-Move larynx as one (elevate and depress)
What are the intrinsic muscles of the larynx?
-Small muscles that move the individual cartilages of larynx relative to each other
-By moving cartilages, they move vocal cords
-This alters quality of speech
What are tonsils?
Collection of lymphoid tissue in the upper parts of the pharynx
What tonsils are found in the nasopharynx?
-Pharyngeal (adenoid) - lies in roof of nasopharynx
-Tubal - surrounds opening of audital tube)
Label this diagram:
What does it show?
Tonsils
What are the two tonsils not found in the nasopharynx?
-Palatine tonsil - lies next to pharyngeal wall in oropharynx
-Lingual tonsil - collection of lymphoid tissue on posterior aspect of tongue
How is the internal larynx modified for its function?
-Function is phonation
-Intrinsic muscles of larynx move laryngeal cartilages
-Laryngeal cartilages move vocal cords that lie inside larynx
What can injury to nerves innervating intrinsic laryngeal muscles cause?
Affect speech
What folds are within the larynx and project into the cavity?
-Two pairs
-Vestibular folds (superiorly) - false vocal cords
-Vocal folds (inferiorly) - true vocal cords
Label this diagram:
What does it show?
Folds within the larynx
What are the vestibular and vocal folds?
-Vestibular - folds of mucous membrane that lie superior to vocal folds
-Narrow space separates vestibular and vocal folds
-Vocal - folds of mucous membrane that cover and protect vocal ligaments
What forms the true vocal cords?
The vocal folds and vocal ligaments
Where is the vocal ligaments attached?
-Anteriorly - internal aspect of laryngeal prominence
-Posteriorly - arytenoid cartilages
What is this?
-Rima glottidis
-Space between the true vocal cords
Describe the changes of the rima glottidis:
-Adduction of true vocal cords closes rima glottidis
-Abduction of folds opens it
-Phonation requires adduction of the cords and closure of the rima glottidis
Describe the different abductions of the rima glottidis:
-Opens rima glottidis
-Small degree = whispering
-Partially = normal breathing
-Fully = forced breathing
What opens and closes the rima glottidis?
Instrinsic muscles of larynx move laryngeal skeleton which moves vocal cords and opens and closes the rima glottidis
What are the 3 intrinsic muscles of the larynx required to know?
-Cricothyroid muscle
-Posterior cricoarytenoids
-Transverse arytenoids
What is this and its function?
-Cricothyroid muscle
-Anterior
-Muscle tips thyroid cartilage anteriorly and inferiorly
-Places tension on vocal cords
What is this and its function?
-Posterior cricoarytenoid muscles
-Posterior surface of cricoid
-Attach to arytenoids
-Abduct vocal cords and open rima glottidis
What is this and its function?
-Transverse arytenoid muscles
-Posterior aspect of larynx
-Connect two arytenoids
-Adduct vocal folds and close rima glottidis
Label:
What nerve innervates the cricothyroid muscle?
-Superior laryngeal nerve
-From vagus
-Sensory to the larynx above the vocal folds
What does the recurrent laryngeal nerve innervate?
-All intrinsic muscles except cricothyroid muscle
-Sensory to larynx below vocal folds
Label:
How many salivary glands are there and their names?
-3 pairs of salivary glands secrete saliva into the oral cavity
-Parotid
-Submandibular
-Sublingual
Label the pink:
What is glandular secretion stimulated by?
Parasympathetic fibres
Describe the parotid gland:
-Largest of 3 paired salivary glands
-Overlies posterior part of mandible
-Saliva empties into mouth via parotid duct - opens adjacent to upper second molar tooth
What is the structure in yellow?
Parotid gland
What is the parotid gland closely associated to?
-Facial nerve
-After exiting skull, nerve enters deep surface of parotid gland
-Within gland, facial nerve divides into 5 branches
-They emerge to innervate muscles of facial expression
-Also closely related to external carotid artery
What nerve stimulates secretion from the parotid gland?
Parasympathetic fibres from glossopharyngeal nerve
Describe the submandibular glands:
-Smaller than parotid
-Part lies within mouth, part lies outside
-Submandibular duct opens into floor of mouth under tongue
What nerve stimulates secretion from the submandibular gland?
Parasympathetic fibres from facial nerve
Describe sublingual glands:
-Small
-Lie on floor of mouth
-Open via several ducts into floor
What nerve stimulates secretion from sublingual glands?
Parasympathetic fibres in the facial nerve
Where doe the right and left coronary arteries arise from and what do they give rise to?
-Ascending aorta
-Several branches
-Each artery and their branches typically supply specific heart regions but variation exists
What does this show?
Coronary arteries arising from ascending aorta
What do cardiac veins return venous blood to?
Coronary sinus which enters right atrium
What is this?
What does the right coronary artery and its branches supply (5)?
-Parts of conducting system
-Right atrium
-Right ventricle
-Part of left ventricle
-Part of interventricular septum
What are the major branches of the right coronary artery?
-Branches to SAN and AVN - supply major components of conducting system
-Right marginal artery - inferior heart border
-Posterior Interventricular Artery - continuation of RCA on inferior heart surface, runs in posterior interventricular sulcus and supplies both ventricles
Where does the posterior interventricular artery run?
Posterior interventricular sulcus
Label this diagram:
What does it show?
RCA and its branches
What does the left coronary artery and its branches supply?
-Parts of conducting system
-Left atrium
-Most of left ventricle
-Part of right ventricle
-Part of interventricular septum
What happens to the LCA after running a short distance?
-Divides into two large terminal brannches
-Short segment is called the left main stem
What are the two terminal branches of the left main stem?
-Circumflex (Cx)
-Anterior interventricular artery
What are the main branches of the left coronary artery and what do they supply?
-Anterior interventricular artery (LAD) - runs in anterior interventricular sulcus towards apex and supplies both ventricles
-1 or 2 diagonal branches
-Circumflex artery - runs around heart to inferior/diaphragmatic surface - supplies left atrium, part of right ventricle and left ventricle
-Left marginal artery - arises from circumflex and supplies left ventricle
Label this diagram:
What does it show?
Left coronary artery and its branches
Where does the posterior interventricular artery arise from and what does it supply?
-May arise from right or left coronary artery
-Origin of posterior interventricular artery determines if someone is left or right dominant
Describe right-dominant circulation:
-Most people
-PIA arises from right coronary artery
-Both right and left coronary arteries supply left ventricle
Describe left-dominant circulation:
-PIV arises from circumflex artery
-Left coronary artery supplies entire left ventricle
Why is the dominance of circulation of the heart important in clinical practice?
-In right-dominant circulation, left stem occlusion would impair blood flow to part of left ventricle
-In left-dominant, blockage of left main stem would occlude blood flow to entire left ventricle
Are all the chambers of the heart anatomically the same?
Why?
-No
-Anatomical differences exist because of different function of different chambers
-Arise from different tissues/ structures during embryonic development
What inside the heart ensures uniderectional flow of blood through the chambers?
Valves
What does the right atrium receive blood from?
-Superior vena cava
-Inferior vena cava
-Coronary sinus
What are the 3 main features of the right atrium?
-Interatrial septum
-Fossa ovalis
-Crista terminalis
Label this diagram:
What is this?
Describe it:
-Fossa ovalis
-Depression in interatrial septum
-Remnant of foetal foramen ovale
-Shunted oxygenated blood from right to left atrium to bypass lungs
What does this show?
Describe it:
-Crista terminalis
-Muscular ridge
-Separates smooth-walled posterior part of atrium from anterior ridged, muscular wall
-Parts on either side of crista have different embryological origins
What are the ridges?
-Pectinate muscles
-Extend into right auricle
Where does the right ventricle pump blood into and what does this bifurcate into?
-Pumps deoxygenated blood into pulmonary trunk
-Bifurcates into right and left pulmonary artery
What prevents the back flow of blood into the right ventricle?
Pulmonary valve
What is the wall of the right ventricle thicker than?
Wall of right atrium
What are the 5 main features of the right ventricle?
-Interventricular septum
-Trabeculae carnae
-Papillary muscles
-Chordae tendinae
-Moderator band
What are these?
Describe them:
-Trabeculae carnae
-Muscular ridges on internal wall of right ventricle
What are these?
Describe them:
-Trabeculae carnae
-Muscular ridges on internal wall of right ventricle
What are these?
Describe them:
-Papillary muscles
-Modified regions of trabeculae carnae
-Project into lumen on ventricle
What are these?
Describe them:
-Chordae tendinae
-Fibrous cords
-Connect tips of papillary muscles to tricuspid valve
What does this show?
Describe it:
-Moderator band
-Modified region of trabeculae carnae
-Connects interventricular septum to one of the papillary muscles
What does the left atrium receive blood from?
-Pulmonary veins
-Two from each lung
Describe the interior wall of the left atrium:
-Smooth-walled posterior
-Anterior part bearing pectinate muscles
-Reflects development from two different embryological structures
What does blood flow through from left atrium to left ventricle?
-Left atrioventicular valve
-Called mitral valve
-Mostly passive but left atrium contracts to further force blood into the ventricle
What are the first branches of the aorta?
Coronary arteries
What prevents the backflow of blood from the aorta into the left ventricle?
Aortic valve
Describe the wall of the left ventricle:
-Thicker than the right ventricle
-Propels blood into the systemic circulation
What are 3 features of the left ventricle?
-Trabeculae carnae
-Papillary muscles
-Chordae tendinae
What valves close during ventricular contraction and what is their function?
-Tricuspid
-Mitral
-Prevent regurgitation of blood back into atria, ensuring the blood can only flow out the ventricles via the great vessels (pulmonary trunk and aorta)
What 2 structures are essential for function of the atrioventricular valves and how do they work?
-Chordae tendinae
-Papillary muscles
-Do NOT close valves
-Allow closed valves to resist pressure generated inside ventricles during contraction and prevent them being forced open
Describe how atrioventricular valves work:
-As ventricular pressure rises, valve cusps projecting into ventricle start to close passively
-When ventricles contract, papillary muscles also contract
-Papillary muscles tense chordae tendinae
-Pull on valve and prevent them inverting into atria
What are the aortic and pulmonary valves called and their function?
-Semi-lunar valves
-Cusps are semi-circular (half-moon)
-Prevent backflow of blood from aorta and pulmonary trunk into the ventricles at the end of ventricular contraction
Describe the semi-lunar valves:
-Each valve has 3 cusps
-Each cusp is attached to inner wall of vessel with a free edge projecting into vessel lumen
-Each cusp forms a pocket called a sinus between its free edge and vessel wall
Label this diagram:
Label this diagram:
Describe the action of the semi-lunar valves:
-During ventricular systole, blood is forcefully propelled from ventricles
-Valves cusps flattened onto vessel walls so blood flows through the vessel unimpended
-End of systole so ventricular pressure drops
-When ventricular pressure is lower than vessel, blood flows back and is caught in the valve cusps
-Sinuses fill with blood and cusps balloon into lumen
-Free edges of cusps contact in lumen and close orifice
When do the coronary arteries fill and why?
-Left and right coronary arteries from 2 of 3 aortic sinuses
-Fill during ventricular relaxation (diastole)
What is the sound you hear when auscultating heart sounds with a stethoscope?
-Closing of valve
-As blood flows through each valve, sounds of valve closing is transmitted in the direction of the blood flow
What different heart sounds can you hear?
-Healthy heart valves have a ‘lub-dub’
-Abnormal or dysfunctional valves produce abnormal sounds called murmers
Where do we listen for heart sounds (general)?
-Listen to heart sounds where sound is transmitted
-Not directly over the valve
-These areas are called auscultatory areas
What are the auscultatory areas for each valve?
-Aortic valve = 2nd intercostal space, just to right of sternum
-Pulmonary valve = 2nd intercostal space, just to left of sternum
-Tricuspid valve = 5th intercostal space, just to right of sternum
-Mitral valve = left 5th intercostal space, midclavicular line
What stimulates myocardial contraction?
Specialised cells in the heart generate and conduct the electrical impulses that stimulate myocardial contraction
What cells generate electrical impulses in the heart?
Location?
-Cells in sinoatrial node (SAN) spontaneously generate electrical impulses
-‘pacemaker’ of the heart
-Located at superior end of crista terminalis
At what rate does the SA node generate impulses?
70 per minute
What do impulses from the SA node stimulate?
Contraction of atria
Where are impulses from the SAN conducted to?
-Location?
-Atrioventricular node (AVN)
-Inferior end of interatrial septum
Where do impulses flow from the AVN?
-Conducting fibres from atrioventricular bundle (Bundle of His)
-Bundle divides into two groups of fibres - right and left bundle branch
Where do impulses flow from bundle branches?
-Left and right bundle branches give rise to purkinje fibres
-Enter myocardium of left and right ventricles and stimulate contraction
What is the SA node supplied by?
BLOOD
-RCA - 60% of people
-LCA - 40% of people
What is the AV node supplied by?
-Usually by posterior interventricular artery
-In most people this arises from RCA
What is the bundle of His supplied by?
Most people - LCA
What can result in conduction abnormalities?
Occlusion of either coronary artery
What external conduction acts on the SA node?
-Heart innervated by parasympathetic and sympathetic fibres
-Act upon the SA node
-Change force and rate of myocardial contraction
-ALSO innervated by visceral afferent fibres
Describe sympathetic innervation to the heart:
-Increases heart rate
-Increases force of contraction
Describe parasympathetic innervation to the heart:
-Slows heart rate
-Slows force of contraction
What do visceral afferent fibres do in terms of the heart?
-Convey sensory information from heart back to CNS
-Usually, sensory info doesn’t reach conscious perception
-If myocardium is ischaemic, visceral sensory info is relayed back to conscious perception
-Can be perceived as pain, burning, tightness or pressure in chest
-Typically not pinpointed, felt generally in chest - referred pain
What are the space in between ribs and what do they contain?
-Intercostal spaces
-Three layers of intercostal muscle and their associated membrane
-Intercostal neurovascular bundle comprising:
-Intercostal nerve
-Intercostal artery
-Intercostal vein
Label this diagram:
What does it show?
Intercostal space and its structures
What are the three intercostal muscles and what do they connect to?
-External
-Internal
-Innermost
-Rib above and belox
-Fibres run in different directions to each other and act on ribs differently
Describe the external intercostal muscles:
-Most superficial
-Antero-inferiorly running fibres
-Contraction pulls ribs superiorly
-In anterior part of intercostal space, muscle becomes membranous and forms external intercostal membrane
Describe internal intercostal muscles:
What does it form posteriorly?
-Deep to external
-Perpendicular to external - postero-inferior
-Contraction pulls ribs inferiorly
-Becomes membranous in posterior part of intercostal space and forms internal intercostal membrane
Describe innermost intercostal muscle:
What are deep to them?
-Posterior part of intercostal space deep to internal
-Fibres orientated in same direction as internal
-Endothoracic fascia deep to innermost intercostal muscle and superficial to parietal pleura
Label this diagram:
Label the diagram:
Where does the intercostal neurovascular bundle lie (plane) and what does it supply?
-In plane between internal and innermost intercostal muscles
-Supplies intercostal muscles, overlying skin and underlying parietal pleura
Where does the neurovascular bundle run? (ribs)
-Along inferior border of the rib superior to the space
-Lies in a shallow costal groove on the deep surface of rib
-In procedures, incision is made to middle/lower part to avoid vessels and nerve
-Smaller collaterla branches run in same tissue plane but in lower
What supplies blood to the anterior and posterior parts of the intercostal space?
Anterior and posterior intercostal arteries
Label this diagram:
What are anterior and posterior intercostal arteries branches of?
-Anterior - branches of internal thoracic artery which is branch of subclavian
-Posterior - branches of descending aorta in posterior thorax
Label this diagram:
What do anterior and posterior intercostal veins drain into?
-Anterior - internal thoracic vein
-Posterior - azygos system of veins
Describe the intercostal nerves:
-Somatic
-Contain motor and sensory fibres
-Innervate intercostal muscles, skin of chest wall and parietal pleura
-Also carry sympathetic fibres
What two layers of membranes cover the lungs and structures passing in and out of them?
-Pleurae
-Parietal - lies inside thorax
-Visceral - covers surface of lungs and extends into fissures
-Thin pleural cavity lies in between parietal and visceral pleura
Label this diagram:
What does it show?
Different surface of pleura
What do the pleural cells produce?
-Small amount of pleural fluid which fills pleural cavity
-Pleura and pleural fluid integral to mechanics of breathing
-Two layers continuous with each other
Label this diagram:
What are the recesses of the pleurae?
-Costodiaphragmatic recess
-Costomedial recess
-‘gutter’ around periphery of diaphragm where pleurae meet each other
-Potential spaces for lungs to expand into during deep inspiration
What innervates the parietal pleura?
-Intercostal nerves that innervate overlying skin of chest wall
-Somatic sensory fibres in these nerves carry sensation to consciousness
-Injury is very painful
What innervates the visceral pleura?
-Autonomic sensory nerves (visceral afferents)
-Usually do not reach conscious perception
What is the apex and base of the lung?
-Apex - most superior part of lung, projects into root of the neck, above clavicle
-Base - sits on the diaphragm
How many lobes does the right lung have?
-3 lobes
-Superior (upper)
-Middle
-Inferior (lower)
How many lobes does the left lung have?
-2 lobes
-Superior
-Inferior
-Anterior extension of superior lobe - lingula extends over heart
Describe the fissures of the lungs:
-Both have an oblique fissure:
-Left lung - separates superior and inferior lobes
-Right lung - separates superior and middle lobes from inferior lobe
-Right lung has horizontal fissure - separates superior lobe from middle lobe
Label this diagram:
What are the surfaces of the lung?
-Costal - adjacent to ribs
-Mediastinal - adjacent to heart
-Diaphragmatic - inferior surface
Label and describe the borders of the lungs:
-Anterior - sharp and tapered
-Posterior - thick and rounded
-Inferior - sharp and tapered
What are seen on the lung surfaces?
-Indentations created by adjacent structures
-Costal - rib markings
-Mediastinal of left - descending aorta and left ventricle
-Mediastinal of right - superior vena cava and azygous vein
What lies in between the heart and lung?
-Root of each lung
-Comprises:
-Pulmonary artery
-Pulmonary veins
-Main bronchus
-Pleura encloses root of lung like a sleeve
What is the hilum?
-Region on mediastinal surface of lung where pulmonary artery, pulmonary veins and main bronchus enter and exit lung
-Positions of pulmonary artery and main bronchus relative to each other different between lungs
What is the difference in positions of structures in the hilums of right and left lungs?
-Right lung - main bronchus is posterior to pulmonary artery
-Left lung - main bronchus lies inferior to pulmonary artery
-Two pulmonary veins usually most anterior and inferior vessels
Where does the trachea bifurcate and what into?
-Level of sternal angle
-Left and right main bronchus
-Right is more vertical, wider and shorter than left so foreign body is more likely to enter right main bronchus than left
What does each main bronchus divide into and how many?
-Lobar bronchi
-3 in right lung
-2 in left lung
What does each lobar bronchi give rise to and how many?
-Segmental bronchi
-10 in each lung
What does each segmental bronchus supply and how many?
-Functionally independent region of lung called bronchopulmonary segment
-10 segments in each lung
-Supplies by own segmental bronchus and blood vessels
-Segement may be resected without affecting rest of lung
What do segmental bronchi divide into?
-Within each bronchopulmonary segment, divide into bronchioles
-Become smaller with each division
-Very smallest conduct air to alveoli
What do the walls of the trachea, bronchi and bronchioles contain?
Under what control are they?
-Trachea and bronchi contain smooth muscle and cartilage
-Bronchioles only contain smooth muscle
-Contraction and relaxation of smooth muscle is under autonomic control
What is the blood supply to lung tissue?
-Bronchial arteries from descending aorta
-Bronchial veins return blood to azygos system of veins
What nerves innervate the lungs?
-Autonomic nerves:
-Parasympathetic fibres:
-Stimulate constriction of bronchial smooth muscle
-Stimulate secretion from glands of the bronchial tree
-Sympathetic fibres:
-Stimulate relaxation of bronchial smooth muscle
-Inhibit secretion of glands
What accompany the sympathetic and parasympathetic nerve fibres of the lungs?
-Visceral afferents (visceral sensory fibres)
-Relay sensory information from lungs and visceral pleura to CNS
-Do not usually reach conscious perception
-
What does lymph from the lungs drain into?
Venous system via thoracic duct or right lymphatic duct
What two things are different in terms of surface markings of the inferior lung?
-Inferior borders of the lungs
-Inferior extent of parietal pleura
-Pleura extends more inferiorly
-Space is costodiaphragmatic recess
Where does the apex of the lung project?
-Lower neck
-Just superior to the medial end of the clavicle
Where does the inferior border of the lungs lie?
-Anteriorly: - 6th rib (midclavicular line)
-Laterally - 8th rib (midaxillary line)
-Posteriorly - 10th rib (vertebral column)
Where does the parietal pleura extend to?
-Anteriorly: - 8th rib (midclavicular line)
-Laterally: - 10th rib (midaxillary line)
-Posteriorly: - 12th rib (vertebral column)
What is the surface anatomy of the oblique fissure?
-Extends from 4th rib posteriorly to 6th costal cartilage anteriorly
-Runs deep to 5th rib
What is the surface anatomy of the horizontal fissure?
Extends anteriorly from 4th intercostal cartilage and intersects with oblique fissure
What is the diaphragm?
Broad, thin, domed sheet of skeletal muscle
Describe diaphragm (4):
-Separates thoracic and abdominal cavities
-Superior (thoracic) surface is adjacent to parietal pleural
-Openings (aperatures) allow passage of structures between thorax and abdomen (aorta, IVC and oesophagus)
-Function integral to mechanics of breathing
What 3 things is the diaphragm attached to?
-Xiphoid process
-Costal margin (and tips of 11th and 12th ribs)
-Lumbar vertebrae
What is the central part of the diaphragm?
-Not muscular - fibrous
-Central tendon
What happens to the diaphragm during inspiration?
-Contracts
-Muscle fibres of right and left domes are pulled towards peripheral attachments
-Domes flatten
-Increases intrathoracic volume for lungs to expand
What happens to the diaphragm during expiration?
-Relaxes and domes superiorly
-Decrease in intrathoracic volume
-Drives air from lungs
What innervates the diaphragm?
-Right and left phrenic nerves
-Innervate right and left sides of diaphragm
-Somatic nerves
-Formed in neck from fibres of C3, C4, C5 spinal nerves
-Contain motor and sensory fibres
In what planes does the dimensions of the thoracic cavity change during ventilation?
-Vertically - diaphragm contraction and relaxation
-Laterally - contraction of intercostal muscles
-Antero-posteriorly - movement of sternum secondary to rib movement
What membranes are essential to ventilation?
-Pleurae and pleural fluid
-Pleural fluid creates surface tension between parietal pleura lining thoracic cavity and visceral pleura on surface of lung
-Keeps lung and thoracic wall together so when thoracic cavity changes volume, lung also changes volume
-Keeps them in contact and prevents lung from collapsing away from thoracic wall
-If surface tension is broken, ventilation may become dysfunctional
What muscles are involved in normal quiet breathing?
-Inspiration is active
-Mainly driven by diaphragm movement
-Expiration is passive
What muscles are involved in vigorous breathing?
-Intercostal muscles become important
-Active expiration uses internal intercostal muscles
What muscles are involved in very vigorous or forced breathing?
-Accessory muscles of breathing contribute to movement of ribs and aid ventilation
-Accessory muscles:
-Sternocleidomastoid
-Pectoralis major
-Pectoralis minor
-Serratus anterior
Label this diagram:
What separates the superior and inferior mediastinum?
-Line that connects sternal angle anteriorly with T4/T5 junction posteriorly
-Point where trachea bifurcates and start and end of aortic arch
What is the inferior mediastinum divided into?
-Anterior
-Middle
-Posterior
Where does the posterior mediastinum lie and what does it contain?
-Behind the heart and pericardium
-Descending aorta
-Azygos vein
-Oesophagus
-Thoracic duct
-Sympathetic trunk and splanchnic nerves
-Posterior intercostal vessels and nerves
What branches from the aorta in the posterior mediastinum?
-Posterior intercostal arteries
-Bronchial arteries
-Oesophageal branches
-Periciardial branches
-Phrenic branches
At what level does the aorta pass through the diaphragm?
T12
Where do the azygos system of veins arise and where do they enter?
-L1/L2
-Traverses diaphragm to enter posterior mediastinum
-Lie on the bodies of the thoracic vertebrae
What does the azygos system of veins drain?
-Drains blood from posterior thoracic wall
-Returns it into the superior vena cava
What is the typical composition of the azygous system of veins?
-Azygos vein on right side of vertebral column
-Small (shorter) hemiazygos vein of left side of vertebral bodies
-One or more veins connecting the two
Label this diagram:
Where does the oesophagus lie in the posterior mediastinum?
To the right of the aorta
What is the blood supply of the oesophagus in the posterior mediastinum?
-Supplied by oesophageal arteries from descending aorta
-Oesophageal veins return venous blood to the azygos system
Under what nervous control is the oesophagus under?
Autonomic control
How does the oesophagus pass from the posterior mediastinum to the abdomen?
-Passes through oesophageal hiatus
-Level of T10
-Most distal part of oesophagus lies inferior to diaphragm
What does the thoracic duct do and where is it?
-Returns most of the body’s lymph to venous system
-Lies between azygos vein and aorta
Label this diagram:
What are these?
What do they do?
-Cisterna chyli
-Lymph from lower limbs, pelvis and abdomen flows towards them
-Sac-like swelling that gives rise to the thoracic duct which ascends into the thorax
What is this?
What does it do?
-Thoracic duct
-In thorax, receives lymph from intercostal spaces and lymph nodes
-Ascends into neck and receives lymph from left side of head and neck and upper limb
-Terminates by opening into venous system at junction between left internal jugular vein and left subclavian vein
Label this diagram:
What does it show?
Termination on thoracic duct
What drains lymph from the right side of the head and neck?
Drained by lymphatic ducts that enter venous system at junction of right internal jugular and subclavian veins
Where does the sympathetic trunk lie?
-Posterior to thoracic wall
-Either side of vertebral column
-Posterior to parietal pleura
What are the sympathetic trunks?
-Thin, longitudinal fibre tracts
-Regularly interspersed with ganglia (collection of cell bodies within the CNS)
What are the ganglia of the sympathetic trunk also known as?
-Paravertebral ganglia
-Lie alongside the vertebral column
Where does the sympathetic trunk run to and from?
From the skull base to the coccyx
Where do cell bodies of preganglionic sympathetic neurons lie?
-Thoracic and upper lumbar spinal cord segments
-T1-L2/L3
What type of fibres are sympathetic fibres and what does this mean?
-Visceral motor fibres
-Leave spinal cord from its ventral aspect and enter spinal nerves T1-L2/L3 along with somatic motor nerves whose bodies lie in ventral grey horn
How do sympathetic fibres reach all of the body?
Sympathetic trunk allows the sympathetic fibres arising from T1-L2/L3 to be distributed to all parts of the body
What is the path of preganglionic sympathetic fibres?
-Exit spinal cord in spinal nerves T1 -L2/L3
-Immediately separate from spinal nerves and enter sympathetic trunk via short communicating/connecting branch (white ramus communicans)
-Once in sympathetic trunk, does one of three things
What do preganglionic sympathetic fibres do once in the sympathetic trunk (3)?
-Synapse in the ganglion at its level of entry
-Ascend or descend in the trunk before synapsing in a ganglion
-Travel through a ganglion (and trunk) without synapsing
What does this show?
What does this show?
What does this show?
In scenarios 1 and 2, what happens next?
-Enter spinal nerves via a communicating branch (grey ramus communicans) (sympathetic fibres enter all 31 pairs of spinal nerves)
-Form visceral nerves that convey sympathetic fibres to head
-Form visceral nerves that convey sympathetic fibres to the thoracic viscera (cardiopulmonary splanchnic nerves)
What are the 4 abdominopelvic splanchnic nerves?
-Greater splanchnic nerve (sympathetic preganglionic fibres from T5-T9)
-Lesser splanchnic nerve (from T10-T11)
-Least splanchnic nerve (from T12)
-Lumbar splanchnic nerves (from L1-L2)
Where do the greater, lesser and least splanchnic nerves form and traverse?
-Formed in posterior mediastinum
-Traverse diaphragm to enter abdomen
-Preganglionic sympathetic fibres ultimately synapse with second neurons in prevertebral ganglia that lie close to blood vessels in abdomen
-After synapsing, postganglionic fibres innervate abdominal viscera
What can you see in the posterior intercostal spaces?
-Intercostal muscles
-Posterior intercostal artery (branch of thoracic aorta)
-Posterior intercostal vein (drains into azygos)
-Posterior intercostal nerve
What are thoracic viscera innervated by?
Both sympathetic and parasympathetic fibres that have coordinated, but generally opposing actions
What main nerves innervate the thoracic viscera?
-Cardiopulmonary splanchnic nerves - convey postganglionic sympathetic fibres
-Vagus nerves convey parasympathetic fibres
What do sympathetic and parasympathetic fibres form around thoracic viscera?
-Autonomic plexuses
-Braid/plait = plexus
-Look like delicate, fine meshes or webs
What nerve plexuses do you find in the thorax?
-Cardiac plexus
-Pulmonary plexus
-Oesophageal plexus
What does the cardiac plexus do?
-Innervates SAN of heart
-Sympathetic fibres increase heart rate and force of contraction
-Parasympathetic fibres decrease heart rate and force of contraction
What does the pulmonary plexus do?
-Innervates bronchi
-Sympathetic relaxes bronchi
-Parasympathetic constricts them
What does the oesophageal plexus do?
-Overlies anterior surface of oesophagus
-Sympathetic fibers inhibit peristalsis
-Parasympathetic stimulate peristalsis
What relay sensory info from thoracic viscera back to CNS?
-Visceral afferents
-Along paths of vagus and thoracic splanchnic nerves
Where do patients with myocardial infarction or angina usually feel pain and why?
-Central chest
-Left side of neck and arm
-Referred pain
What innervates the heart?
-Cardiac plexus
-Composed of sympathetic and parasympathetic fibres
-Sympathetic fibres travel to cardiac plexus and heart from spinal cord segments T1-T5 via cardiopulmonary splanchnic nerves
What other nerves also innervate the heart?
-Visceral sensory nerves
-Travel back to CNS alongside sympathetic fibres innervating heart and enters T1-T5
-Convey sensory info from heart back to CNS
-normally not reach conscious perception
-If myocardium is ischaemic, can be interpreted as pain, tightness and crushing in conscious perception
Explain cardiac referred pain:
-Somatic sensory info from skin of chest wall, neck and arm also return to T1-T5
-Same segments as visceral sensory nerves of heart
-Brain interprets cardiac pain as coming from chest, neck and arm
What is another example (other than cardiac) of referred pain?
-Diaphragm referred pain
-C3-C5 contribute spinal nerve fibres to phrenic nerve
-These segments also contribute to nerves that innervate skin of neck and shoulder
-Brain interprets diaphragm pain as coming from shoulder region
Where is the mediastinum?
-Part of thoracic cavity
-Lies between the lungs
-Contains all thoracic viscera apart from lungs
-Extends from:
-Superior thoracic aperature superiorly to diaphragm inferiorly
-Sternum anteriorly to thoracic vertebrae posteriorly
What viscera does the mediastinum contain?
-Heart and pericardium
-Great vessels that enter and leave heart
-Veins that drain chest wall
-Trachea and main bronchi
-Oesophagus
-Nerves
-Lymphatics
-Thymus gland
What line separates the superior and inferior mediastinum?
Sternal angle to T4/T5 junction
What does the inferior mediastnum separate into?
-Anterior
-Middle
-Posterior
Where does the anterior mediastinum lie and what does it contain?
-Between posterior aspect of sternum and anterior aspect of pericardial sac
-Narrow space
-Contains thymus gland in children and its remnant in adults
What does the middle mediastinum contain?
-Heart inside pericardial sac
-Pulmonary trunk and ascending aorta
Where does the posterior mediastinum lie?
Posterior aspect of pericardial sac and the vertebrae
What are the main contents of the superior mediastinum?
-Arch of aorta and its three branches
-Superior vena cava and its tributaries (brachiocephalic veins)
-Trachea
-Oesophagus
-Phrenic nerves and vagus nerves
-Thoracic duct
-Thymus gland
Label this diagram:
What does it show?
Contents of superior mediastinum
What are the 3 parts of the aorta in the thorax?
-Ascending aorta - short, first part:
-Gives rise to coronary arteries
-Arch of aorta:
-Curves posteriorly
-Lies in superior mediastinum
-Descending (thoracic) aorta:
-Descends through posterior mediastinum
-Into abdomen posterior to diaphragm
What 3 main branches does the arch of the aorta give in the superior mediastinum?
-Brachiocephalic trunk:
-Bifurcates into right common carotid - supplies right side of head and neck and right subclavian - supplies right upper limb
-Left common carotid - supplies left side of head and neck
-Left subclavian - supplies left upper limb
Label this diagram:
Where are aortic bodies and what do they do?
-Arch of the aorta
-Chemoreceptor location
-Constantly monitor arterial oxygen and carbon dioxide
How is info from aortic bodies carried?
-Visceral sensory information
-Travels back to CNS along path of vagus nerve
-Results in reflex responses that regulate ventilation
What is this?
Describe:
-Ligamentum arteriosum
-Fibrous cord-like connection between pulmonary trunk and arch of aorta
-Remnant of ductus arteriosus - foetal circulatory shunt
What is the ductus arteriosus?
Describe what happens to it:
-In foetus, gas exchange occurs at placenta not lung
-Diverts most blood entering pulmonary trunk directly into aortic arch
-When a baby starts to use thier lungs at birth, ductus arteriosus closes and blood into pulmonary trunk enters lungs
What two veins return blood to the right atrium?
-Superior vena cava
-Inferior vena cava
What does the SVC return blood from?
-Head
-Neck
-Upper limbs
LIES IN SUPERIOR MEDIASTINUM
What forms the SVC?
Union of left and right brachiocephalic veins
What forms each brachiocephalic vein?
Union of internal jugular vein and subclavian vein
Label this diagram:
What does it show?
Formation of left and right brachiocephalic veins
Where does the IVC return blood to the heart from?
-All regions inferior to the diaphragm
-Thoracic part is very short - as soon as it enters thorax through diaphragm, it enters heart
Where does the trachea start and end?
-Extends from larynx in midline of neck to superior mediastinum - palpable just superior to suprasternal notch
-Terminates at level of sternal angle (junction of T4/T5) by bifurcating into left and right main bronchi
Where does the oesophagus run in the mediastinum?
-Midline of the thorax
-Posterior to trachea
-Descends into posterior mediastinum
Where do the left and right phrenic nerves form and what do they innervate?
-Formed from fibres from C3,4 and 5 spinal nerves
-Innervate diaphragm
What is the path of the phrenic nerves?
-Descend through neck
-Into thorax through superior thoracic aperture
-Course over the pericardium and pierce the diaphragm
What nerves are these?
Where do the left and right vagus nerves arise?
What fibres do they contain?
What do they innervate?
-CNX
-Arise from brainstem
-Contain somatic sensory, somatic motor and parasympathetic fibres
-Innervate structures of the thorax, abdomen and head and neck
Describe the path of the vagus nerve in the neck:
-Descends alongside the internal carotid artery and internal jugular vein
-Enter thorax via superior thoracic aperture
What do each of the vagus nerves give rise to in the superior mediastinum?
-Recurrent laryngeal nerves
-Ascends back up into the neck to innervate muscles of larynx
Label the diagram:
What do the right and left recurrent laryngeal nerves loop around?
-Left :
-Under arch of aorta
-Ascends back up to left side of neck
-Along trachea
-Right:
-Descends to anterior to right subclavian artery
-Loops under inferior border of right subclavian artery
-Ascends up right side of neck
-Between trachea and oesophagus
Where do the vagus nerves descend and what do they contribute?
-Descend into thorax posterior to root of lung
-Contribute parasympathetic fibres to heart, lungs and oesophagus
-Traverse diaphragm and convey parasympathetic fibres to most of abdominal viscera
Where does the thoracic duct run in the mediastinum?
-Ascends through posterior mediastinum and into superior mediastinum
-Empties into venous system at union of internal jugular vein and subclavian vein
What is the thymus and where does it lie?
-Lymphoid organ
-Lies anteriorly in the superior mediastinum
-Important in children but atrophies with age becoming fatty
What is the pericardium?
-Tough, fibrous sac
-Encloses the heart like a loose-fitting bag to allow movement of the heart
What two layers is the pericardium composed of and what do they connect to?
-Tough outer fibrous layer:
-Attached superiorly to the great vessels
-Attached inferiorly to central tendon of diaphragm
-Thin inner serous layer:
-Has 2 part (parietal and pleural)
Describe the two layers of the serous pericardium:
-Parietal layer - lines inner aspect of fibrous pericardium
-Visceral layer - covers surface of heart
CONTINUOUS
Label this diagram:
What is the narrow space in between the two layers of serous pericardium?
-Pericardial cavity
-Small amount of pericardial fluid
-Lubricates serous membranes and allows them to slide over each other with movements of the heart
What innervates the fibrous pericardium?
-Phrenic nerves
-Sensory branches
What is the point of the heart called?
Apex
What are the surfaces of the heart?
-Base - faces posteriorly so is called the posterior surface
-Inferior surface - lies on central tendon of the diaphragm, also called diaphragmatic surface
-Anterior surface - faces sternum and ribs so is called sternocostal surface
-Left and right sides face lungs so called pulmonary surfaces
Label this diagram:
What does it show?
Surfaces of heart
What parts of the heart do each surface correspond to?
-Base/posterior = left atrium, part of right atrium
-Inferior/diaphragmatic = left ventricle, part of right ventricle
-Anterior/sternocostal = right ventricle
-Left pulmonary = left ventricle
-Right pulmonary = right atrium
What forms the apex of the heart and where does it lie?
-Formed by left ventricle
-Left 5th intercostal space
-In midclavicular line
-Apex beat palpable here
In what way do we describe the heart which is important in x-rays?
-Edges (borders)
-Correspond to specific parts of the heart
Which borders of the heart correspond to specific parts of the heart?
-Right border = right atrium
-Left border = left ventricle
-Inferior border = right ventricle and part of left ventricle
What is the position of the right border of the heart relative to?
-Lateral to sternal edge
-From right 3rd costal cartilage to right 6th costal cartilage
What is the position of the left border of the heart relative to?
Extends from left 2nd intercostal space to left 5th intercostal space in midclavicular line (apex)
What is the position of the superior border of the heart relative to?
-Lies along line connecting superior extents of right and left borders
-Right 3rd costal cartilage to the left 2nd intercostal space
What is the position of the inferior border of the heart relative to?
-Lies along line connecting inferior end of right border with apex
-Mostly formed by right ventricle
What are these?
Describe them:
-Auricles (auricular appendiges)
-Ear-like appearance
-Outpouchings from walls of left and right atria
Where is the sternum?
Anteriorly in the midline of the thoracic cage
Label this diagram:
Describe the manubrium:
-Superior part of sternum
-Superior border has suprasternal (jugular) notch
-Laterally articulates with clavicle (sternoclavicular joint) and with first rib
-Inferiorly articulates with body of sternum (manubriosternal joint) also known as sternal angle or angle of louis
Describe the body of the sternum:
-Articulates ribs 2-7
-Second rib articulates with sternum at sternal angle
-Inferiorly articulates with xiphoid process
Describe the xiphoid process:
-Small and variable in shape
-Seventh rib articulates with inferior part of sternal body and superior part of xiphoid process
What does the red line show?
What is it composed of?
-Costal margin
-Costal cartilages of ribs 7-10
-Palpable
How many pairs of ribs are there and what do they form?
-12 pairs
-Anterior, lateral and posterior walls of thoracic cage
What are the anterior parts of the ribs composed of?
Costal cartilage
Label this diagram:
What are these?
-Costochondral joints
-Where ribs articulate with their costal cartilages
Label this diagram:
What does it show about the ribs?
-Ribs 1-7 = true (costal cartilages articulate directly with sternum)
-Ribs 8-10 = false (unite and join the seventh costal cartilage)
-Ribs 11-12 = floating (short and do not articulate with sternum)
Where do the ribs articulate posteriorly?
-Articulate with thoracic vertebrae
-Costovertebral joints
What are adjacent ribs joined by?
Intercostal muscle which lie in intercostal spaces
What is the classification of ribs?
-Typical - look similar and share common anatomical features
-Atypical - look different to typical ribs / or lack some of the features of typical ribs
Which ribs are typical and atypical?
-Typical = ribs 3-9 (head, neck, tubercle and body)
-Atypical = 1-2, 10-12 (1,11,12 much shorter)
Label this diagram:
What lies posterior to the midline of the thoracic cage?
-12 thoracic vertebrae (T1-T12)
-Spinous processes palpable in midline of back
-Articulate with posterior parts of ribs at costovertebral joints
-Head of rib articulates with vertebral body and tubercle of rib articulate with transverse process
What does this show?
Superior thoracic aperture
What is the superior thoracic aperture and what forms it?
-Passageway through which structures pass between neck and the thorax
-Manubrium, first ribs and first thoracic vertebrae form boundary
What can be articulated at the sternal angle?
Second rib
Label this diagram:
What innervates the skin of the thoracic wall?
-Spinal nerves T1-T12
-Sensation from skin of thoracic wall (touch, pain, temperature) reaches conscious perception via somatic sensory fibres in spinal nerves
Describe innervation of skeletal muscles, sweat glands and smooth muscle in thoracic wall:
-Somatic motor fibres in spinal nerves T1-T12 innervate skeletal muscles of thoracic wall
-Sympathetic fibres innervate sweat glands and smooth muscle of blood vessels and hair follicles in skin
What are each of these segments?
-Dermatomes
-Area of skin innervated by a single spinal nerve
-Each pair of thoracic spinal nerves supply a strip around the chest wall
What are the breasts?
-Mammary glands
-Superficial to muscles of chest wall
-Well developed in females
-Grow during puberty and pregnancy
-Breast tissue extends towards anterior axilla (armpit) - called axillary tail
What happens to the breasts after menopause?
-Atrophy
-Difficult to study in female cadavers
What 5 things do the breasts contain?
-Fat
-Glandular/secretory tissue
-Ducts which converge at nipple (areola is pigmented region of skin)
-Connective tissue and ligaments
-Blood vessels and lymphatics
What is the main blood supply to the breast?
-Internal thoracic artery (arises from subclavian artery):
-Course deep to edge of sternum
-Gives rise to anterior intercostal arteries that supply breast and intercostal spaces
-Axillary artery
-Axillary vein
-Internal thoracic veins
What innervates the breasts?
-Somatic nerves and sympathetic fibres via the intercostal nerves
-Somatic sensory fibres innervate the skin of the breast
-Sympathetic fibres inner ate smooth muscle in the blood vessel wall and nipple
Where does most lymph from the breast drain from?
-Drains to lymph nodes in the axilla
-Patterns are complex as axillary nodes communicate with other groups of lymph nodes in the thorax
Describe the lymph nodes of the axilla:
-5 groups
-Central, pectoral, humeral, subscapular, apical
-Drain breast, upper limb, chest wall, scapular region and abdominal wall
-Apical nodes receive lymph from all other types of lymph nodes in the axilla
-As they drain most of the lymph from the breast, they are most involved in the spread of breast cancer
Label the 5 groups of axilla lymph nodes:
Where do the intercostal muscles lie?
What are the 3 layers of muscle in the intercostal spaces?
-External intercostal - most superficial
-Internal intercostal - deep to external
-Innermost intercostal - deep to internal
Label this diagram:
What do the intercostal muscles do?
-Collectively move the ribs and alter the dimensions of thoracic cavity
-During inspiration and expiration
What are the three upper limb muscles of the thorax?
-Pectoralis major - most superior
-Pectoralis minor - smaller muscle deep to pectoralis major
-Serratus anterior
What are the three upper limb muscles of the thorax?
-Pectoralis major - most superior
-Pectoralis minor - smaller muscle deep to pectoralis major
-Serratus anterior
Where does the pectorals major connect?
-Upper humerus
-Clavicle
-Upper six ribs
Where does the pectoralis minor connect?
-Scapula
-Ribs 3-5
Where does serratus anterior connect?
-Sweeps around lateral aspect of thoracic cage
-Attaches scapula and upper 8 ribs
What are the prime functions of the pectoralis muscles?
-Move upper limb
-Pectoralis major - adducts humerus
-Pectoralis minor + serratus anterior - protract scapula
What are the other functions of the pectoralis muscles?
-Accessory muscles of breathing
-Attach to ribs and hence move ribs if humerus and scapula are fixed
-Sign of respiratory distress
