Anatomy Flashcards
What is the blood supply of the lungs
Bronchial arteries
Left - off decending aorta
Right - off right 3rd posterior intercostal artery
Innervation of diaphragm and intercostals
Diaphragm is the major inspiratory muscle - phrenic motor neurons that lie in the cervical spinal cord (C3–C5).
Intercostal and abdominal muscles - thoracolumbar spinal cord, from T1–T11 and T7–L2, respectively.
Innervation to the smooth muscle of the airways
The parasympathetic nervous system provides the most important innervation via the laryngeal and vagus nerves. Cholinergic and excitatory, reducing airway diameter (via mAChR).
Sympathetic innervation of smooth muscle is scant. Preganglionic sympathetic axons exit at T4 and post-ganglionic adrenergic fibers elicit bronchodilation, acting through B2-AR.
Thoracic inlet contents
Oesophagus Apex of lung Brachiocephalic artery Left subclavian Left common carotid Left and Right brachiocephalic vein Trachea Vagus and phrenic nerves
Superior mediastinum
○ Arch of Aorta § + origin of branches ○ Superior Vena Cava § +receiving vessels (L+R brachiocephalic veins) ○ Vagus and phrenic nerves ○ Sympathetic trunk ○ Thymus ○ Trachea ○ Oesophagus
Anterior mediastinum
• Anterior
Thymus
Middle mediastinum
○ Heart ○ Pericardium ○ Tracheal bifurcation + L+R Main bronchi ○ Ascending aorta ○ Pulmonary trunk ○ Superior vena cava ○ Phrenic nerves
Posterior mediastinum
○ Thoracic aorta § Posterior intercostals § Left Bronchial § Oesophageal § Superior phrenic ○ Oesophagus ○ Azygos system of veins ○ Sympathetic trunks
What are internodal pathways
Internodal pathways from SA to AV nodes - 3, made of purkinje fibres
Innervation of the heart
The heart is innervated byvagal and sympathetic fibers. The right vagus nerve primarily innervates theSA node, whereas the left vagus innervates theAV node; however, there can be significant overlap.
Sympathetic fibre from the sympathetic chain
Effects of autonomic nervous system on the heart
○ Vagal
§ Negative chronotropy - SA node - M2
§ Negative inotropy - at least in atria - M2
§ Negative dromotropy - AV node - M2
§ Possible vasoconstriction of the coronary arteries - M2
○ Sympathetic
§ Positive chronotropy - SA node - B1
§ Positive inotropy - Atria + Ventricles (increased intracellular Ca) - B1
§ Positive dromotropy - AV node - B1
§ Vasodilation of the coronary arteries - B2 adrenoceptors - circulating epinephrine (no direct innervation)
Innervation of blood vessels
Sympathetic adrenergic fibres run in the adventitia of arteries and veins
• Alpha 1 adrenoceptors cause arteriovenous smooth muscle contraction and therefore vasoconstriction
• Alpha 2 adrenoceptors cause arteriovenous smooth muscle contraction however the negative feedback on NA secretion means that Alpha 2 agonists cause vasodilation
• Beta 2 adrenoceptors in the coronary arteries reduce arteriovenous smooth muscle contraction causing vasodilation
Common congenital heart defects
- VSD
- ASD
- Tetralogy of Fallot
- Single ventricle defects
- Pulmonary valve stenosis
- Patent ductus arteriosus
- Dextro-Transposition of the great arteries
- Aortic valve stenosis
- Dextrocardia
- Ebstein´s abnormality
Congenital - Ventricular septal defect
20% of Congenital heart disease - surgery if heart failure
Congenital - Atrial septal defect
80% close spontaneously before adulthood, occasional treatment required
Tetralogy of Fallot
Overriding aorta, Pulmonary stenosis, VSD and Right ventricular hypertrophy. All get surgery either before or at 6 months
Single ventricle defects
Range of defects - all require a number of surgeries
Congenital - Pulmonary valve stenosis
if severe needs balloon valvuloplasty
Patent ductus arteriosus
if symptomatic, closure using drugs, surgery or catheter procedures
Dextro-Transposition of the great arteries
10% of CHD - surgery during first week of life
Dextrocardia
sometimes surgery
Ebstein´s abnormality
inferiorly displaced tricuspid valve. Causes WPW & HF -
treated with medications or surgery
Foetal circulation
Placenta - umbilical vein - ductus venosus - IVC - RA - foramen ovale + RV - LA + pulmonary artery - ductus arteriosus + LV - aorta … internal iliac arteries - umbilical arteries - placenta
Cells of the brain
neurons - responsible for sending and receiving nerve impulses glial cells (glia, neuroglia) - non-neuronal cells that provide support and nutrition, maintain homeostasis, form myelin and facilitate signal transmission - number of glia 50x that of neurons
Dura Mater
The outer layer is called the periosteal dura.
An inner layer, the dura, lines the inside of the entire skull and creates little folds or compartments in which parts of the brain are protected and secured. The two special folds of the dura in the brain are called the falx and the tentorium. The falx separates the right and left half of the brain and the tentorium separates the upper and lower parts of the brain.
Arachnoid
The second layer of the meninges is the arachnoid. This membrane is thin and delicate and covers the entire brain. There is a space between the dura and the arachnoid membranes that is called the subdural space. The arachnoid is made up of delicate, elastic tissue and blood vessels of varying sizes.
Pia Mater
The layer of meninges closest to the surface of the brain is called the pia mater. The pia mater has many blood vessels that reach deep into the surface of the brain. The pia, which covers the entire surface of the brain, follows the folds of the brain. The major arteries supplying the brain provide the pia with its blood vessels. The space that separates the arachnoid and the pia is called the subarachnoid space. It is within this area that cerebrospinal fluid flows.
CSF production and absorption
Production - The choroid plexus in the ventricles
Absorption - The arachnoid granulations
Ventricular system of the brain
- Lateral ventricles. Communicate with the third ventricle through a separate opening called the Foramen of Munro.
- The third ventricle is in the center of the brain, and its walls are made up of the thalamus and hypothalamus. The third ventricle connects with the fourth ventricle through a long tube called the Aqueduct of Sylvius.
- CSF flowing through the fourth ventricle flows around the brain and spinal cord by passing through foramina of Luschka and Magendie.
Brainstem
Midbrain - Important centre for ocular motion
Pons - Involved with coordinating eye and facial movements, facial sensation, hearing and balance.
Medulla oblongata - Controls breathing, blood pressure, heart rhythms and swallowing.
Reticular activating system is found in the midbrain, pons, medulla and part of the thalamus. Controls levels of wakefulness, enables people to pay attention to their environments and is involved in sleep patterns.
Cerebellum
- Separated from the cerebrum by the tentorium (fold of dura).
- The cerebellum fine tunes motor activity or movement
- Helps maintain posture, sense of balance or equilibrium, by controlling the tone of muscles and the position of limbs.
- Important in ability to perform rapid and repetitive actions such as playing a video game.
- In the cerebellum, abnormalities produce symptoms on the same side of the body.
Cerebrum
- The two hemispheres are joined at the bottom by the corpus callosum which delivers messages from one half of the brain to the other.
- The surface of the cerebrum contains billions of neurons and glia that together form the cerebral cortex “gray matter.”
- Beneath the cerebral cortex or surface of the brain, connecting fibers between neurons form “white matter.”
- Stimulating the left primary motor cortex would cause the right side of the body to move.
Cranial nerves
- Olfactory:Smell
- Optic:Visual fields and ability to see
- Occulomotor:Eye movements; eyelid opening
- Trochlear:Eye movements
- Trigeminal:Facial sensation
- Abducens:Eye movements
- Facial:Eyelid closing; facial expression; taste sensation
- Vestibular:Hearing; sense of balance
- Glossopharyngeal:Taste sensation; swallowing
- Vagus:Swallowing; taste sensation
- Accessory:Control of neck and shoulder muscles
- Hypoglossal:Tongue movement
Functions of the hypothalamus
releasing hormones regulating body temperature maintaining daily physiological cycles controlling appetite managing of sexual behavior regulating emotional responses
Functions of the frontal lobes
• The frontal lobes are the largest of the four lobes.
• Motor skills such as voluntary movement
○ The areas that produce movement in parts of the body are found in the primary motor cortex or precentral gyrus
• Speech functions
○ Broca’s area, important in language production, is found in the frontal lobe, usually on the left side.
• Intellectual functions
○ The prefrontal cortex plays an important part in memory, intelligence and concentration
• Behavioral functions
○ The prefrontal cortex plays an important part in temper and personality
Functions of the occipital lobes
• These lobes are located at the back of the brain
• Receive and process visual information
○ Influence how humans process colours and shapes.
○ The occipital lobe on the right interprets visual signals from the left visual space, while the left occipital lobe performs the same function for the right visual space.
