Summary of sympathetic nervous system

Sympathetic nervous system is the part of autonomic nervous system .

Functionally Nervous system can be divided into two part
somatic nervous system and autonomic nervous system .
Sympathetic system is the part of autonomic nervous system

•Like somatic nervous system autonomic nervous system has two parts •Motor part of autonomic system innervate smooth muscle, cardiac muscles  and most of the glands of the body
•Sensory part of autonomic system carry sensory impulse from viscera to the brain . Sensory parts of autonomic system usually ran along the sensory system of somatic system so we often perceive visceral pain in the body wall .

short description of sympathetic nervous system

Topics	Sympathetic nervous system
Out flow	it is also known as thoraco lumbar outflow T1 to L 2
Pre ganglionic fibres	Short
Post ganglionic fibres	Longer
Ganglia	Para vertebral sympathetic ganglia  is away from the target organ
Location of pre-ganglionic neuron	•       Lateral horn cells of all thoracic segments and upper two or three lumbar segments of spinal cord
Location of post-ganglionic neuron	•       Lateral: sympathetic trunk •       Collateral : coeliac, superior mesenteric ganglia •       Terminal ganglia: supra-renal medulla
	This system activate during emergency and works during stress and strain for fight or flight
	Liberates non adrenaline at postganglionic ending except eccrine type of sweat glands and most of the blood vessels of skeletal muscle
	This system is not essential for to life
Urinary bladder	It is the nerve of filling It contract (close) urethral sphincter and relax detrusor muscles
Heart	Cardiac muscles cells : increase force of contraction Coronary vessels :  vasodilator ( so supply of nutrition and oxygen increase in cardiac muscle cells  )
Lung:	Bronchodilator / Trachealis muscles relax so diameter of trachea increase Decrease secretion of tracheal glands
Stomach	Gastric musculature (smooth muscle cells ) is relax  but smooth muscle cells at the pyloric sphincter is contract (closer of pyloric sphincter )
Small gut	Inhibit peristalsis Vasoconstriction (vaso motor)
Summary : effect	•       Produce mass reaction •       Cutaneous blood vessels undergo vasoconstriction but, skeletal and coronary vessels are dilated thus supplying more blood to the muscles, heart, brain. Heart rate is increased, blood pressure and blood sugar are elevated , pupil and bronchi are dilated. Intestinal peristalsis is suppressed and the sphincters of gut are closed.
Eye	Pupil dilates
*Uterus	Uterine contraction Vasoconstriction
Salivary glands	_
Pancreas	_
Gastric glands	_
Adrenal glands	secretomotor
Vessels of Skeletal muscle	Vasodilatation
Sweat gland	secretomotor
Afferents	Convey most of the visceral pain except pelvic organ
Cells of origin of afferents fibres	Dorsal root ganglia of T 1 to L1/L2
Central control	Posterior part of hypothalamus

Summary of parasympathetic ganglion of head and neck region

Para-sympathic ganglion of head and neck

Topics	Ciliary	Pterygopalatine
Nucleus of origin	Edinger-westphal nucleus in midbrain	Superior salivary nucleus in pons
Site of ganglion	Posterior lateral to optic nerve in orbit	Pterygopalatine fossa inferior to maxillary nerve
Preganglionic pathway	3rd nerve via branch to inferior oblique muscle	Facial nerve via greater superficial petrosal nerve & nerve of pterygoid canal
Post-ganglionic pathway	Short ciliary nerves	Greater & lesser palatine nerves &  sphenopalatine nerves Lacrimal nerves
Organ of destination	Ciliary body Sphincter pupillae	Palate Nose Lacrimal gland

Topics	Sub-mandibular	Otic
Nucleus of origin	Superior salivatory nucleus in pons	Inferior salivatory nucleus in medulla
Site of ganglion	On hyoglossus muscle inferior to lingual nerve	Inferior to foramen ovale outside skull
Preganglionic pathway	Facial nerve via chorda tympani & lingual nerve	Glossopharyngeal nerve via tympanic & lesser petrosal branches
Post-ganglionic pathway	Lingual nerve	Auriculotemporal nerve
Organ of destination	Sublingual & submandibular glands	Parotid glands

Ossification : easy and brief description

Ossification: it is the process of bone formation

Classification of ossification centre:

1. A primary ossification center is the first area of a bone to start ossifying.

 It usually appears during intra-uterine life in the central part of each developing bone.

Exception: carpal bones of hand

 In long bones the primary ossification centers appear in the diaphysis/shaft and in irregular bones the primary centers appear usually in the body of the bone.

All long bones have only one primary center but some irregular bones such as the hip bone and vertebrae have multiple primary centers.

2. Secondary ossification centre: A secondary ossification center is the area of ossification that appears after the primary ossification center has already appeared - most of which appear during the postnatal and adolescent years. Most bones have more than one secondary ossification center. In long bones, the secondary centers appear in the epiphyses (upper and lower end).

Classification of mechanism of ossification

Membranous ossification:

Ex: head and neck: parietal bone, frontal bone, maxilla, zygomatic,

Sup extre: clavicle

Cartilaginous ossification: all vertebrae, all ribs, sternum, scapula, all bones of upper limb except clavicle, all bones of lower limb

Membrano-cartilaginous ossification:

Occipital: membranous ossification area above the highest nuchal line, rest of the parts arises from cartilaginous ossification  

Sphenoid: membranous ossification above the lateral part of greater wing and pterygoid process except the hamulus, rest of the part arises from cartilage,

Temporal: membranous ossification – squamous part and tympanic part, rest of the parts arises from cartilage,

 Mandible: cartilaginous ossification anterior part of body and part of ramus above mandibular foramen, rest of the body arises from membranous ossification

Name of bone	Primary ossification center	Secondary ossification center
Clavicle	Two	One for sternal end
Humerus	One for shaft	Three for upper end – head , greater & lesser tubercle Four for lower end – lateral & medial epicondyle, capitulum, trochlear
Radius	One primary ossification center for shaft	One for upper end One for lower end
Ulna	One primary ossification center for shaft	One for upper end One for lower end
Carpal bone	One primary ossification center which appear after birth	No secondary ossification centre
Metacarpal bone	One primary ossification center for shaft	One 2nd ossification centre :  base of  1st metacarpal bones is ossified from 2nd ossification center Heads of  2-5 metacarpal bone are ossified from 2nd ossification center
Phalanges	One primary ossification center for shaft and head	One 2nd ossification center for base  of each phalanx

Lower limb

Name of bone	Primary ossification center	Secondary ossification center
Hip bone	Three – ilium, ischium, pubis	5 secondary ossification center
Femur	One for shaft	Three for upper end – head , greater & lesser trochanter One for lower end
Tibia	One primary ossification center for shaft	One for upper end One for lower end
Fibula	One primary ossification center for shaft	One for upper end One for lower end
Tarsal bone (except calcaneus)	One primary ossification center	No secondary ossification centre
Calcaneus	One primary ossification center	One secondary ossification centre
Metatarsal bone	One primary ossification center for shaft	One 2nd ossification centre :  base of  1st metatarsal bones is ossified from 2nd ossification center Heads of  2-5 metatarsal bone are ossified from 2nd ossification center
Phalanges	One primary ossification center for shaft and head	One 2nd ossification center for base  of each phalanx

Handout on occipital bone : helpful for viva examination

Occipital

1.       Anatomical  points:

·         Occipital condyles are directed  downwards

·         Basilar part is directed forwards and upwards

·         External surface of squamous part is convex and directed backward

2.       Morphological type : Flat bone

3.       Structure of bone : inner and outer compact and middle diploe

4.       Ossification :  area of occipital bone above the highest nuchal line  is arisen from membranous ossification and rest of the parts of occipital bone is arisen from cartilaginous ossification

5.       Development : paraxial mesoderm

6.       Parts : Squamous part , basilar part and condylar part

Squamous part :

1.       Two surfaces : external and internal

External surface of squamous part

·         External occipital protuberance : gives attachment to the highest point of the ligamentum nuchae

·         Highest nuchal line : gives attachment to epicranial aponeurosis :

·         Superior nuchal line:  its

·          medial part attached with origin of trapezius muscle and

·          lateral part from before backwards attached with origin of occipital belly of occipito frontalis muscle and insertion of sternocleidomastoid and splenius capitis

·         Inferior nuchal line: medially:  rectus capitis posterior minor and

                                     Laterally rectus capitis posterior major  

·         External occipital crest : gives attachment of ligamentum nuchae

·         Area between superior and inferior nuchal line :

·          medially insertion of semispinalis capitis and

·          laterally obliquus capitis superior  

·         Area between inferior nuchal line and foramen magnum

·         Medially attachment of rectus capitis posterior minor and

·         laterally attachment of rectus capitis posterior major

Internal surface of squamous part of occipital bone

Internal occipital protuberance : an irregular elevation opposite the external occipital protuberance

Sagittal sulcus : lodges superior sagittal sinus and its margin of sulcus attached with falx cerebri

Transverse sulcus  (right and left)  : lodges  transverse sinuses  and its margin of sulcus attached with tentorium cerebella

Right transverse sinus is the continuous of superior sagittal sinus and

left transverse sinus is the continuous of straight sinus

Internal occipital crest lodges occipital sinus and its margin attached with falx cerebelli.

Fossae :

Two upper triangular fossae : lodge occipital lobes of the cerebrum with meninges

Two lower quadrilateral fossae : lodge cerebellar hemispheres

Vermian fossa: a small depression which lodge vermis of the cerebellum

Angles:

Superior angle :  is meeting points of occipital bone and two parietal bone

Lateral angle : is the meeting points of occipital bone, parietal bone and mastoid part of temporal bone

Two lambdoid borders: they are articulates with posterior border of occipital bone

Two mastoid borders: they are articulates with mastoid part of temporal bone

Basilar part of occipital bones

Parts

2.        Three surfaces and three borders

3.       Anterior surface: articulate with body of sphenoid , forming primary cartilaginous joint , ossifies by the end of the 25^th years

4.       Smooth Superior surface (also known as clivus) it is related with meninges , ligament , lower part of pons and medulla oblongata , near the foramen magnum it is related with following structures above downward

·         Membrana tectoria

1.       Upper band of crucial ligament

2.       Apical ligament

3.       Anterior atlanto –occipital membrane

Inferior surface of basilar part of occipital bone :

Pharyngeal tubercle: a small middle bony elevation attached with fibrous raphe of pharynx and superior constrictor muscle

Lateral to pharyngeal tubercle : insertion of longus capitis muscles

Behind the attachement of longus capitis or in front of occipital condyles : insertion of rectus capitis anterior

Borders of basilar part of occipital bones

Posterior border is formed the anterior margin of foramen magnum

Two Lateral borders : articulate with petrous part of temporal bone

Condylar part of occipital bone

Parts

Superior surface : contain jugular tubercle an oval eminence overlying the hypoglossal canal

Inferior surface:

Two Occipital condyles : articulate with superior articular processes of atlas forming atlanto –occipital joint

Hypoglossal canals : they are  situated anterior part of each condyle

 transmits :

1.       Hypoglossal nerve

2.       Meningeal branch of ascending pharyngeal artery 

3.       Emissary vein connecting basilar venous plexus with pterygoid venous plexus

Condylar fossa : a depression behind the condyle

Condylar canal occationally a foramen present within the condylar fossa which transmit emissary vein connect sigmoid sinus with veins of suboccipital triangle

Jugular process : it is situated just lateral to occipital condyles

Anterior surface of jugular process bears jugular notch which form jugular foramen by articulating with petrous part of temporal bone

Jugular foramen : transmitted

1.       Anterior compartment  :  inferior petrosal sinus

2.       Middle compartment : glossopharyngeal

Vagus nerve , accessory nerve 

Meningeal branch of ascending pharyngeal artery

Emissary vein

3.       Posterior compartment :

Sigmoid sinus continued as internal jugular vein

Foramen magnum:

Smaller anterior compartment transmits

1.       Apical ligament

2.       Upper band of cruciate ligament

3.       Membrane tectoria

Larger posterior compartment transmits

1.       Lower end of medulla oblongata

2.       Right and left vertebral artery

3.       Anterior and posterior spinal artery

4.       Spinal root of accessory nerve

5.       Sympathelic plexus of nerves

6.       Veins joining the venous plexus of medulla oblongata

7.       Lower part of tonsil of cerebellum

Jugular foramen:

1. glossopharyngeal nerve : mixed nerve : sensory supply motor supply
2. vagus nerve : mixed nerve : sensory supply  motor supply
3. Cranial root of accessory nerves: motor nerve. supply
4. Internal jugular vein