Neurological disease associated with Corpus Stariatum

 There are several neurological diseases that are associated with the corpus striatum, including:

1. Parkinson's disease: Parkinson's disease is a neurodegenerative disorder that affects movement control. It is characterized by the loss of dopamine-producing neurons in the substantia nigra, which leads to dysfunction in the nigrostriatal pathway that supplies dopamine to the striatum. This dysfunction in the striatum contributes to the motor symptoms of Parkinson's disease, including tremors, rigidity, and bradykinesia.

2. Huntington's disease: Huntington's disease is a genetic disorder that causes the progressive degeneration of the striatum, particularly the caudate nucleus. This results in a range of symptoms, including involuntary movements, cognitive decline, and behavioral changes.

3. Dystonia: Dystonia is a movement disorder that is characterized by involuntary muscle contractions that cause repetitive or twisting movements. It is often caused by dysfunction in the basal ganglia, including the striatum.

4. Tourette syndrome: Tourette syndrome is a neuropsychiatric disorder that is characterized by the presence of multiple motor and vocal tics. It is believed to be caused by dysfunction in the basal ganglia, including the striatum.

5. Obsessive-compulsive disorder (OCD): OCD is a mental disorder that is characterized by the presence of obsessive and/or compulsive behaviors. Dysfunction in the cortico-striatal-thalamo-cortical (CSTC) circuit, which involves the striatum, is believed to play a role in the development of OCD.

Corpus Striatum - connections and function

The corpus striatum, also known as the striatum, is a complex brain region that receives input from various brain regions and is involved in several functions, including movement control, reward processing, and decision-making.

The striatum receives input from the cortex, thalamus, and substantia nigra. The corticostriatal pathway is particularly important, as it carries information from the cortex to the striatum. The thalamostriatal pathway also plays a role in conveying sensory information to the striatum, while the nigrostriatal pathway supplies dopamine to the striatum, which is important for reward processing and motivation.

The striatum is involved in several important functions, including:

1. Movement control: The striatum plays a crucial role in controlling voluntary movements. It receives input from the cortex and thalamus, and its output is sent to the motor cortex, which initiates and coordinates movements. Dysfunction in the striatum is implicated in several movement disorders, including Parkinson's disease, Huntington's disease, and dystonia.

2. Reward processing: The striatum is involved in processing reward-related information and plays a critical role in motivation and decision-making. It receives dopamine from the substantia nigra, and dopamine release in the striatum is associated with feelings of pleasure and reward. Dysfunction in the striatum is implicated in several addictive and compulsive behaviors, such as drug addiction and gambling addiction.

3. Cognitive functions: The striatum is also involved in several cognitive functions, including learning, memory, and attention. It plays a role in learning and habit formation, as well as in regulating attention and inhibiting unwanted behaviors.

The striatum receives input from various brain regions and is involved in several important functions, including movement control, reward processing, and cognitive functions. Dysfunction in the striatum is implicated in several neurological and psychiatric disorders, and studying its connections and function is important for developing new treatments for these conditions.

An overview of Corpus Striatum Structure

Striatopallidodentatocalcification, also known as Neurodegeneration with Brain Iron Accumulation (NBIA), is a rare genetic disorder characterized by the abnormal accumulation of iron in certain areas of the brain.

The condition is caused by mutations in genes that regulate iron metabolism in the brain, which leads to excessive accumulation of iron in specific brain regions, including the basal ganglia, which includes the striatum, globus pallidus, and substantia nigra, and the dentate nucleus of the cerebellum.

The excess iron accumulation leads to the formation of abnormal structures, including neurofibrillary tangles and abnormal deposits of calcium, resulting in progressive damage to the affected brain regions. This damage can lead to a range of neurological symptoms and complications, including movement disorders, cognitive impairment, psychiatric symptoms, and seizures.

The specific pathophysiology of striatopallidodentatocalcification is not fully understood, but it is believed to involve disruption of the normal functioning of brain cells, particularly those involved in movement control, which leads to the characteristic symptoms of the condition. Additionally, the accumulation of iron and other abnormal structures can lead to inflammation and oxidative stress, which further exacerbates brain damage.

There is currently no cure for striatopallidodentatocalcification, and treatment options are primarily supportive and symptomatic. These may include medications to manage movement disorders, physical therapy to improve mobility and muscle strength, and supportive care to address any other complications or symptoms that arise.

Blood supply of internal capsule

Blood supply of internal capsule comes from 3 main arteries they are

Lateral striate branches of middle cerebral artery.
Medial striate branches of anterior cerebral artery.
Anterior choroidal branches of internal carotid artery.

Lateral striate branches of middle cerebral artery supply

1. Anterior limb.
2. Genu.
3. Posterior limb.
4. Basal ganglia.

Medial striate branches of anterior cerebral artery supply

1. Anterior limb.
2. Genu.
3. Basal ganglia.

Anterior choroidal branches of internal carotid supply

1. Posterior limb.
2. Retrolenticular part.

Anterior limb is supplied by the following arteries

1. Ant cerebral artery through medial striate branch.
2. Middle cerebral artery through lateralstriate and lenticulostriate branches.

Genu is supplied by

1. Anterior cerebral artery through medial striate branch.
2. Middle cerebral artery through lateral striate and lenticulostriate branch.
3. Branches of internal carotid artery.

Posterior limb is supplied by

1. Middle cerebral artery through lateral striate and lenticulostriate branch. It is called Charcot’s artery of cerebral haemorrhage.
2. Anterior choroidal artery, direct branch of internal carotid artery As it is long and slender it has tendency to get thrombosis.

Lacrimatory pathway

Following are the components of the lacrimatory pathway

• Lacrimatory nucleus  facial nerve.
• Greater superficial petrosal joins with deep petrosal nerve to form nerve of pterygoid canal  which pass through the pterygopalatine fossa where there is pterygopalatine ganglion.
• Zygomatic branch of maxillary nerve.
• Zygomaticotemporal nerve.
• Communicating branch to lacrimal nerve - lacrimal gland.The lacrimal nerve is  derived from the ophthalmic nerve and it innervate the sensory component of the lacrimal gland.

Physiology of Ocular Movement

There are 3 planes of movement of eyeball
Vertical plane 

• Adduction - Medial rectus 
• Abduction - Lateral rectus

Horizontal plane 

• Elevation - Superior Rectus and inf. oblique
• Depression - Inferior Rectus and Superior oblique

Diagonal plane 

• Intorsion - Superior rectus and Superior oblique
• Extorsion - Inferior rectus and Inferior oblique

Normal range of eye movement

• Abduction - 60°
• Adduction - 50°
• Depression - 50°
• Elevation - 30°

Types of  ocular movement

• Saccadic movement-jerky voluntary movement from an object to another
• Pursuit movement-smooth follow movement
• Fixation movement-move the head while the gaze is fixed
• Reflex movement-oculocephalic, oculovestibular movement.

Symptoms of ocular motor system
Diplopia, squint, ptosis, defective vision,dizziness (ocular vertigo).

Anatomical peculiarity of facialnerve

Facial nerve is a Sensorimotor nerve with the following functions

• Special visceral efferent (facial muscle)
• General visceral efferent (submandibular, sublingual and lacrimal glands)
• Special visceral afferent (taste from anterior two-thirds of tongue)
• General somatic afferent (sensation from external auditory meatus, mastoid and pinna)

The upper half of the face has a bilateral representation ,whereas the lower half of the face has unilateral representation.
Nuclei of facial nerve are 4 in number
Motor nucleus contains dorsal and ventral group of cells and is situated in ventral pons
Superior Salivatory nucleus control salivation
Nucleus of tractus solitaries carry taste sensation from anterior 2/3 rd of tongue and sensation from external auditory meatus
Lacrimal nucleus. for lacrimation

There is two types of movements voluntary and reflexmovements
Volitional movement
There is supranuclear connection for volitional movement
It is unique for facial nerve
For Volitional movement the fibers start from  lower part of precentral gyrus , corticonuclear fibers descend to pons and cross to opposite facial nucleus. Nucleus  for the superior half of facial muscles receiving ipsilateral and contralateral supranuclear fibers. Nucleus  for the inferior half of facial muscles mainly receive contralateral supranuclear fibers .This explains why the upperhalf is spared in UMN lesion and only lower half is affected.
Variation
Occasionally lower half of face also has ipsilateral supranuclear innervation but it is less than contralateral innervation. This will result in only paresis of lower half in UMN lesion, if ipsilateral supranuclear innervation is also equal to contralateral  innervation both upper half and lower half may escape in UMN lesion.
Rarely upper half will have innervation predominantly from contralateral fibers. Thus in UMN lesion there is extension of weakness to upper half of face also.
For reflex movement 
Fibers from premotor area, extrapyramidal center, basal ganglia, through separate pathway, innervate the Nucleus from both sides but predominantly from Right cortex.
Lesion of this pathway produce Mimic facial palsy.
Nervus intermedius
It is the  Sensory counter part of facial nerve,it carry fibers of Superior Salivatory nucleus, lacrimal nucleus, and Nucleus of tractus solitarius.
It subserves the following
Somatic sensation of mastoid region ,part of pinnae, external auditory canal
Secretomotor fibers to lacrimal gland, salivary glands - sublingual and submandibular and
Visceral sensation – taste sensation from ant. 2/3rd of tongue.

Branches facial nerve

Branches at the Geniculate ganglion 

• Greater superficial Petrosal nerve -supplies secretomotor fibers to lacrimal gland

Braches of Vertical mastoid segment

• Nerve to stapedius
• Chorda tympani -arise 5 mm above the stylomastoid foramen, carry taste sensation from anterior 2/3rd of tongue. It supplies secretomotor fibers to submandibular and sublingual gland

Branches at the level of Stylomastoid foramen

• Posterior auricular braches-supplies occipitalis and auricular muscles
• Digastric – Posterior belly of digastric
• Stylohyoid supplies stylohyoid muscle

Branches in the Parotid region 
Temporofacial  branch

• Temporal
• Zygomatic
• Upper buccal

Cervicofacial branch

• Lower buccal
• Mandibular
• Cervical.

They supply muscles of face, scalp, and platysma.

Course of the facial nerve -the 7th cranial nerve

Key anatomical area you should remember in relation to anatomy of the facial nerve are the following

• Pons
• CerebelloPontine angle
• Internal auditory meatus
• Middle ear 
• Stylomastoid foramen

Intrapontine segment 
Pons
Facial nuclei is situated in the pons
Sensory and parasympathetic fibers are carried by nervus intermedius
It curves around the 6th nerve nucleus to form facial collicullus and form the first genu around the 6th Cranial nucleus
Cerebellopontine  Angle
Nerve emerges at the ventrolateral portion of pontomedullary junction with Nervus intermedius and 8th nerve and lies in the cp angle
Meatal segment
Enters the internal auditory meatus with the 8th nerve with the nervus intermiedius in between
Labyrinthine segment
It  dip into the facial canal in the floor of meatal canal, reaches the medial part of tympanic cavity form the 2nd genu - geniculate ganglion – receives the Nervus intermedius.
It curves posteriorly at the genu giving the Greater superfical petrosal nerve at the genu
Then it travels backwards in the horizontal direction (tympanic segment is above the middle ear)
Mastoid segment
It turns back vertically downwards to emerge through stylomastoid foramen, then turns vertically in the vertical (mastoid) segment
It gives nerve to stapedius and chorda tympani nerve in the vertical part
Parotid region
The facial nerve emerge through the Stylomastoid Foramen and enters the parotid region
It emerges at the stylomastoid foramen
Leaves  the parotid gland by dividing to temperofacial and cervicofacial branches
finally divides into five terminal motor branches

Anatomical peculiarities of 3,4,6th cranial nerve

The 3rd cranial nerve-oculomotornerve
The oculomotor nuclear complex is located in the the middbrain at the level of superior colliculus. This has one unpaired and four paired nuclear columns.
The unpaired column constitute

• Edinger-Westphal nucleus
• Subnucleus for levator palpebrae superioris. 

The paired nuclei constitutes

• Subnuclei for superior, inferior and medial recti and inferior oblique.

4th cranial nerve-Trochlear nerve

• Trochlear nerve passes posteriorly and the fibres from the right and left trochlear nuclei decussate on the dorsum of mid brain. 
• This is the only cranial nerve that emerges dorsally from the brainstem. 
• The left trochlear nucleus sends fibres to the right superior oblique muscle and vice versa.

6th cranial nerve-Abducent nerve 

• Abducent nerve has a very long intracranial course and supplies the lateral rectus muscle..
• Because of its long intracranial course, this  nerve  is affected in conditions producing raised intracranial tension, hence producing a false localizing sign.

Regions of abdomen and its contents

For purposes of description abdomen is conveniently divided into 9 regions by the intersection of imaginary planes there are 2 horizontal and 2 sagittal planes.
The horizontal planes
The upper horizontal plane[transpyloric] lies at a level midway between the suprasternal notch and the symphysis pubis,that is at the level of L1 vertebra (transpyloric plane)
The lower plane passed through the upper borders of the iliac crests at the level of tubercles of the iliac crest.
The sagittal planes or vertical planes
The sagittal planes are indicated on the surface by lines drawn vertically midway between the pubis and anterior superior iliac planes. You have to drop two vertical lines from the mid point of clavicle on either sides.
The regions of abdomen  are:

• Right hypochondrium
• Left hypochondrium
• Epigastrium
• Right lumbar region
• Left lumbar region
• Umbilical region
• Right iliac fossa
• Left iliac fossa
• Hypogastrium.

Contents of different regions of abdomen

• Right hypochondrium - Right lobe of liver, gallbladder, hepatic flexure of colon
• Epigastrium - Left lobe of liver, stomach, transverse colon, lower end of oesophagus and oesophagogastric junction
• Left hypochondrium - Fundus of stomach, spleen, tail of pancreas, splenic flexure of colon
• Right lumbar region - Right kidney and its suprarenal gland, right ureter, ascending colon
• Umbilical region - Aorta, IVC, portions of stomach, head and body of the pancreas, duodenal loop, mesentery, small intestinal loops, lymph nodes
• Left lumbar region - Left kidney and its suprarenal gland, left ureter and descending colon, spleen if it enlarges grossly
• Right iliac fossa - Caecum, appendix, part of ascending colon, lymph nodes, right ovary and fallopian tube
• Hypogastrium - Urinary bladder, uterus in females, sigmoid colon and rectum
• Left iliac fossa - Part of the descending colon, part of sigmoid colon, left ovary and fallopian tube, lymph nodes.

Surface marking of Kidney

Surface marking of kidney is done by drawing the Morris parallelogram .
Two parallel horizontal lines are drawn on the back at the levels of 11 th thoracic and 3rd lumbar spines.
These two horizontal lines are intercepted by 2 vertical lines drawn 3.75 and 8.75 cm respectively from midline.

Surface marking of Liver

Surface marking of upper border of liver
Upper border of right lobe corresponds to the level of 5th rib, 2.5 cm medial to the right midclavicular line.

• 5th Right intercostal space - Midclavicular line
• 7th Right intercostal space – Midaxillary line
• 9th Right intercostal space - scapular line -Inferior angle of scapula

Upper border of left lobe is at the level of 6th rib in left mid clavicular line.
In men, it corresponds to a line joining a point about 1 cm below the right nipple to a point about 2 cm below the left nipple.
Surface marking of lower border of liver 
Lower border  follows the right costal margin, in the epigastrium, it is from the tip of the 9th Right costal cartilage to the tip of the 8th costal cartilage on the left by an oblique line midway between the xiphisternum and umbilicus.
The left lobe extends to the left of the sternum about 5cm.

Surface marking of Spleen

Spleen is situated behind 9th, 10th and 11th ribs with its long axis along the line of 10th rib; anteriorly it extends to mid axillary line while posteriorly its superior angle is 4 cm  lateral to 10th thoracic spine. It is separated from 9th, 10th and 11th ribs by the diaphragm.
Surface marking of spleen can be done by joining 3 points

• 9th Left intercostal space – midclavicular line.
• 1.5" to the left of 10th spine
• 3.5" to the left of 1st lumbar spine

Surface marking of Gallbladder

Gall bladder is situated at the junction of 9th costal cartilage and outer border of right rectus abdominis muscle
Grey-Turner’s Method
Draw a line from left anterior superior iliac spine through umbilicus. At the junction of this and the costal margin, is the gallbladder, provided the shape of abdomen is normal. Gallbladder is better seen than felt when enlarged.

Characteristics of coronary circulation -explained

Key characteristics of  coronary circulation

• Coronary circulation is very short , rapid, and  phasic .
• Blood flow mainly occur during cardiac diastole
• No efficient anastomoses between the coronary vessels.
• It is a rich circulation (5% of the CO ,as heart wt is 300gm)
• Regulation of coronary circulation is mainly by metabolites and not neural
• Capillary permeability is high (the cardiac lymph is rich in protein)
• Vessels are susceptible to degeneration and atherosclerosis.
• Evident regional distribution of blood flow is noticed (subendocardial layer in LV receives < blood, due to compression (but normally compensated during diastoles by V.D).Hence it more prone to IHD+MI.
• Eddy current keep the valves away from the orifices of arteries it keeps the orifices patent throughout the cardiac cycle.
• As having highest O2 uptake achieved by a dense network of capillaries, all is perfused at rest (no capillary reserve)

The Coronary artery

• Coronary artery represent the enlarged vasavasorum of larger vessels in the heart.
• They are about the width of a drinking straw tht is 1/8 inch (4mm) .
• The term Coronary comes from the latin word ”Coronarius= “Crown”. 
• Coronary artery arises from the coronary sinuses just superior to the aortic valve behind the cusps

It has 3 cusps

• Left coronary (LC), 
• Right coronary (RC)
• Posterior non-coronary(NC) cusps.  

The left coronary artery

Left coronary artery is about 10-15mm long
It arises from left coronary cusps
Left coronary artery almost immediately bifurcate into
1. left anterior descending

• Diagonal Branch supply most of Anterior Left ventricular wall, A small part of  rightventricle
• Septal perforating Branch supply anterior 2/3rd to interventricular septum
• A part of the left branch of the AV bundle
• Terminal branch supply the cardiac apex

2. Left circumflex artery.
The right coronary artery

Origin R anterior coronary sinus origin of Valsalva
It courses through the right AV groove
Branches ;
1. Conus branch
1st branch supplies the RVOT• Sinus node artery
2nd branch - SA node.(in 40% they originate from LCA)        
2.Acute marginal arteries-Arise at acute angle and runs along the margin of RV above the diaphragm. 3, Whole of the conducting system of the heart, except part of the left br of AV node
4. Posterior descending artery : Supply lower part of the ventricular septum & adjacent ventricular walls. Arises from RCA in 85% of case.
Branches of first and second segment of RCA
Branches of 1st Segment: 

• Anterior Atrial Branch
• Artery to SA node
• Anterior Ventricular Brs
• Right Marginal Artery

Branches of 2nd Segment

• Posterior Ventricular branch
• Posterior Interventricular branch
• Posterior Interventricular (descending) Artery
• Septal branch
• AV nodal Artery

Venous drainage of heart

There are 2 systems:
There is superficial and deep venous system
Superficial system: which drains the left ventricle. It is formed of coronary sinus and anterior cardiac veins  which opens into the right atrium.
Deep system: It drains the rest of the heart. It is formed of the basian veins and arterio-sinusoidal vessels that open directly into the heart chamber.
Anastomotic channels

Between coronary arteries & extracardiac arteries there is intercoronary anastomosis
IN NORMAL HEART THERE ARE NO COMMUNICATIONS BETWEEN THE LARGE CORONARIES.
ANASTOMOSES DO EXIST AMONG THE SMALLER ARTERIES SIZED 20 TO 250 µ m.
There is three common areas of anastomoses.
    1. Between branches of LAD & PIV OF RCA in iv groove
    2. Between LCX & RCA IN AV groove.
    3. Septal branches of 2 coronary arteries in the IVS
What is the Lifesaving value of collaterals in heart?
It there is occlusion in one of the larger coronary within seconds;
Dilatation n of small anastomoses( blood flow < ½)-normal or almost normal coronary (within 1 month).
Small branches of the LAD (left anterior descending/anterior interventricular) branch of the left coronary join with branches of the posterior interventricular branch of the right coronary in the interventricular groove. More superiorly, there is an anastomosis between the circumflex artery (a branch of the left coronary artery) and the right coronary artery in the atrioventricular groove. There is also an anastomosis between the septal branches of the two coronary arteries in the interventricular septum. The photograph shows area of heart supplied by the right and the left coronary arteries.

Derivatives of the pharyngeal pouches

The pharyngeal pouches are balloonlike diverticula that formed on the endodermal side between the pharyngeal arches.The pairs of pouches develop in a craniocaudal sequence between the arches

During the embryonic development pharyngeal pouches develop between the branchial arches .The first pharyngeal pouches pouch is situated between the first and second branchial arches. There are 4 pairs, the 5th pouch is absent or very small.The pharyngeal pouches form on the endodermal side between the pharyngeal arches and the pharyngeal grooves or clefts form the lateral ectodermal surface of the neck region to separate the arches.The endoderm of the pharyngeal pouches and the ectoderm of the branchial grooves contact each other to form the branchial membranes and this will seperate  the pharyngeal pouches and the branchial grooves.

The primordial pharynx , derived from the foregut it widens cranially where it joins the primordial mouth or stomodeum.It narrows caudally where it joins the esophagus
Derivatives of the 1st pharyngeal pouch 
1st pharyngeal pouch expands into a tubotympanic recess
The expanded distal portion of the recess contacts the 1st branchial groove .It is the only branchial membrane to persist in the adult.This will be contributing to the formation of the tympanic membrane or eardrum.
Only the 1st branchial groove persists in the adult as the external acoustic meatus .
The tubotympanic recess gives rise to the tympanic cavity and the mastoid antrum.
Connection between the tubotympanic recess and the pharynx elongates to form the auditory tube.
Mandibular nerve supply derivatives of first pharyngeal pouch
Derivatives of first pharyngeal pouch

• Middle ear
• Mastoid antrum
• Inner layer of the tympanic membrane
• The endoderm lines the future auditory tube

Derivatives of the 2nd pharyngeal pouch
2nd pharyngeal pouch contributes to the formation of the following Palatine tonsil  and epithelial lining of the fauces.The endoderm of the pouch proliferates and grows into the underlying mesenchyme,the central parts of these buds form crypts .The endoderm of the pouch forms the surface epithelium and the lining of the tonsillar crypts. At about 20 weeks the mesenchyme around the crypts differentiates into lymphoid tissue.These tissues soon organize into the lymphatic nodules of the palatine tonsil
2nd pouch derivatives are supplied by the facial nerve.

Derivatives of second pharyngeal pouch

• Palatine tonsil
• Epithelial lining of the fauces
• Middle ear

Derivatives of the 3rd pharyngeal pouch
3rd pharyngeal pouch has dorsal and ventral wings and contributes to the formation of the inferior parathyroid glands (week 5- bulbar portion and the thymus (elongate portion). which migrate inferiorly past the superior parathyroid glands of the 4th pouch.
Derivatives of this pouch is supplied by glossopharyngeal nerve .
Derivatives of 3rd pharyngeal pouch

• Derivatives of the dorsal wings include the inferior parathyroid glands,
• Ventral wings fuse to form the cytoreticular cells of the thymus

Derivatives of the 4th pharyngeal pouch
4th pharyngeal pouch contributes to the formation of the superior parathyroid gland (bulbar portion) and the parafollicular cells or calcitonin cells of the thyroid gland (elongate portion form ultimobranchial body).
Superior laryngeal nerve supply the derivatives of this pouch
Derivatives of 4th pharyngeal pouch

• Superior parathyroid glands 
• Ultimobranchial body which forms the parafollicular C-Cells of the thyroid gland
• Musculature and cartilage of larynx (along with the sixth pharyngeal arch).

Derivatives of the 5th pharyngeal pouch
It is a rudimentary structure and becomes part of the fourth pouch contributing to formation of thyroid C-cells.
Derivatives of the 6th pharyngeal pouch 
The sixth pharyngeal pouch does not exist. The fourth and sixth arches contribute to the formation of the musculature and cartilage of the larynx. These structurs are supplied by Recurrent laryngeal nerve.

What are the derivatives of the branchial arch muscles ?

1st branchial arch give rise to the following structures

• Muscles of mastication
• Mylohyoid and anterior belly of the digastric
• Tensor tympani
• Tensor veli palatini

2nd branchial arch give rise to the following structures

• Muscles of facial expression
• Stapedius
• Stylohoid
• Posterior belly of the digastric

3rd branchial arch give rise to the following structures

• Stylopharyngeus

4th and 6th branchial arches give rise to the following structures

• Cricothyroid
• Levator veli palatini
• Constrictors of the pharynx
• Intrinsic muscles of the larynx
• Striated muscles of the esophagus

The serratus anterior and winging of scapula

This muscle is not strictly a muscle of the pectoral region. 

Origin of Serratus anterior

This muscle arises by eight digitations from the upper eight ribs, and from the fascia covering the intervening intercostal muscles.

Insertion of Serratus anterior

The muscle is inserted into the costal surface of the scapula along its medial border

The first digitation is inserted from the superior angle to the root of the spine. 

The next two or three digitations are inserted lower down on the medial border. 

The lower four or five digitations are inserted into a large triangular area over the inferior angle.

Nerve Supply of Serratus anterior

The nerve to the serratus anterior is Long thoracic nerve a branch of the brachial plexus.It arises from roots C5. C6 and C7.

Actions of Serratus anterior

• Serratus anterior helps in pushing and punching movements.Along with the pectoralis minor it pulls the scapula forwards around the chest wall to protract the upper limb 
• The fibres inserted into the inferior angle of the scapula pull it forwards and rotate the scapula so that the glenoid cavity is turned upwards. This action of the serratus anterior is helped by the trapezius muscle which pulls the acromion upwards and backwards.
• When the serratus anterior is paralysed the medial margin of the scapula gets raised specially when pushing movements are attempted. The patient is unable to do any pushing action, nor can he raise his arm above the head. Any attempt to do these movements makes the inferior angle of the scapula still more prominent.It is called winging of the scapula.
• The muscle_steadies the scapula during weight carrying.
• It helps in forced inspiration. Serratus anterior is an accessory muscle of respiration

Clinical testing of  Serratus anterior

Forward pressure with the hands against a wall, or against resistance offered by the examiner makes the inferior angle of the scapula prominent (winging scapula) if the serratus anterior is paralyzed.

Development of human heart

Separation of the Atria from the Venticles in the embryo
Ventricular septum development and defect
Development of interatrial septum
Development of interatrial septum and its defect (ASD)
Atrial septal defect types and clinical features
Development of human Arterial System