Surface anatomy of heart : with points for drawing on living body

 

Heart:

 

1Apex of the   Heart

It is situated in the left 5^th intercostal space just medial to midclavicalar   line.

Related questions:  How it is formed?

Ans: It is formed by only left ventricle of the heart.

2.     Right   border of the Heart

1^st point: On   the upper border   of the right 3^rd costal cartilage about 2.5 cm from the median   plane.

2^nd point: on   the right 6^th costal cartilage about 2.5 cm from the median plane

Join these two points by a convex line towards the right.

SN: (The maximum convexity of which lies at a distance of 3.25am from the median plane in the 4^th intercostal space.)

Related questions:

How it is formed?  Ans: it is formed by right atrium

3. Left Border of Heart

1) 1^st    Point – On the lower border of the left 2^nd costal cartilage about 2.5 cm from the median plane.

2) 2^nd   point- At the apex beat left 5^th intercostal space just medial to mid-clavicular line Join   these two points by line with convexity directed upwards and to the left.

Related questions:

How it is formed? Ans: it is formed by left ventricle of the heart

4. Lower border of the Heart

1^st point: on   the right 6th costal cartilage about 2.5 cm from the median plane

2^nd   point-At the apex beat left 5^th intercostal space just medial to mid-clavicular line

Join these two points with slight notch to the right of the apex of the heart.

Inferior border passes through the xiphisternal junction

 Related questions: How it is formed? Ans: it is formed by mostly by right ventricle and partly by left ventricle

5. Upper border of the Heart

1^st point: On   the upper border   of the right 3^rd costal cartilage about 2.5 cm from the median   plane.

2^nd point: On the lower border of the left 2^nd costal cartilage about 2.5 cm from the median plane.

Join these points.

Related questions: How it is formed? Ans: 1/3 of right atrium and 2/3 of left atrium are formed this border

6. Arch of the Aorta

1) 1^st point –On the right end of the   sternal angle.

2) 2^nd point –On the   centre of the manubrium   sterni

3)3^rd point- sternal end of left 2^nd costal cartilage 

Join the points by a curved line which represents the outer border of the arch of aorta; then the inner   border is drawn   below  &  paralled to it about 2.5 cm apart  .

Importance points :  It is the continuation of ascending aorta and It is continued as descending thoracic aorta

Related questions : What are the branches of arch of aorta?

1.       brachiocephalic artery/ trunk : right common carotid and right subclavian artery

2.       left common carotid artery

3.       left subclavian artery

What is the type of these arteries?  Ans : elastic artery.

Why they known as elastic artery? They contain large numbers of elastic lamina within the tunica media. 

Basal nuclei : lecture notes

 

Basal nuclei

Terminology related to basal nuclei

Nerurological structure	Basal nuclei
Corpus striatum	Caudate nucleus + lentiform nucleus
Amygdala	Amygdaloid nucleus
Claustrum	Claustrum
Neostriatum	Caudate nucleus +putamen
Paleostriatum	Globus pallidus
Caudate nucleus	Caudate nucleus
Lentiform nucleus	Globus pallibus +putamen

 

Basal nuclei

•        They are the large masses of grey matter situated within the white core of each cerebral hemisphere

•        They form essential part of extra pyramidal system

•        Parts :

1. Corpus striatum : it has two parts

•        caudate nucleus:  neostriatum : relatively new

•        Lentiform nucleus : it has two part i) globus pallidus (paleostriatum: relatively ancient) ii) putamen: neostriatum : relatively new ) 

2. Claustrum

3. Amygdaloid body

Corpus striatum

•        It is situated lateral to the thalamus

•        It is formed by caudate nucleus and lentiform nucleus

•        Internal capsule, a band of nerve fibres divide the lentiform nucleus and caudate nucleus

Caudate nucleus

•        It is a comma shaped grey matter surround thalamus

•        Parts : head, body and tail

•        Amygdaloid body attached with terminal end of tail of caudate nucleus

Lentiform nucleus

•        It is a lens shaped grey matter

•        It forms lateral boundary of internal capsule

•        It has two part :

    i) globus pallidus (paleostriatum: relatively ancient)

     ii) putamen: neostriatum : relatively new )

Claustrum

•        It is a thin saucer shaped mass of grey matter

•        It is situated between putamen and insula 

Amygdaloid body

•        It is an almond shaped mass of grey matter in the temporal lobe

•        It is situated deep to uncus

•        Developmentally it is related to basal nuclei but functionally it is included in the limbic system

Connection of corpus striatum

•        Afferent fibres come from cortex, thalamus , substantia nigra

•        Efferent fibres goes to mainly in globus pallibus

•        Fibres of globus pallidus goes to thalamus

Function of basal nuclei

1. Regulate muscle tone
2. smoothening the voluntary motor activities of the body
3. Control automatic associated movements like swinging of arms during walking

Disorders of the basal ganglia

•        Disturbance of muscles tone

•        Unwanted involuntary movement

•        Name of disease: parkinsonism :

•        Resting tremors ( pill rolling tremor)  : diminished during movement

•        Loss of facial expression

•        Shuffling gait

•        Cogwheel type of muscular rigidity

Development of female urethra

Development of female urethra

The development of male and female urethra is different .

The female urethra is short and its development is very simple but male urethra is long and its development is complicated

The development of male urethra is intimately related to the development of external genital organs

The epithelium of entire female urethra and most of the male urethra is derived from urogenital sinus

Uregenital sinus is developed from cloaca

What is cloaca ?

Cloaca : part of hindgut (derived from endoderm) caudal to attachment of allantois, which is common chamber for hindgut & urinary system

It is divided into two parts ventral and dorsal by urorectal septum
ventral part is called primitive urogenital sinus
dorsal part is called primitive rectum

What are the parts of primitive urogenital sinus ?

Vesico-urethral canal and definitive urogenital sinus

From above down ward different parts of primitive urogenital sinus

1.      Upper part of vesico-urethral canal

2.      Lower part of vesico-urethral canal

3.      Pelvic part of definitive urogenital sinus

4.      Phallic part of definitive urogenital sinus 

Development of female urethra 

Parts of primitive urogenital sinus	Female urethra
1.      Lower part of vesico-urethral canal	Most of the part of female urethra (upper part)
2.      Pelvic part of definitive urogenital sinus	Small part of female urethra (lower part)
3.      Phallic part of definitive urogenital sinus	Vestibule of female external genitalia into which the urethra is opened  (external opening )

SN: only the lining epithelium of the urethra is derived from endoderm of urogenital sinus

Epiphysis : definition, types epiphyseal cartilage, growing end

 Epiphysis: it is the parts of a growing long bone which ossify from secondary ossification center.

Types of epiphysis:

Pressure epiphysis: it transmits body weight. Ex:  head of femur

Traction epiphysis: it is produce by pull of muscles EX:  trochanter of femur 

Atavistic epiphysis: coracoid process of scapula. Coracoids process is independent bone unit with scapula for nutrition.

Aberrant epiphyses: This Epiphysis is not always present. For example: the epiphyses at the head of the first metacarpal bone

Epiphyseal cartilage: it is the plate of hyaline cartilage situated between the epiphysis and diaphysis. The plate is found in children and adolescents; In adults, who have stopped growing, the plate is replaced by an epiphyseal line.

One of the steps of Intracartilaginous ossification occurs in epiphyseal cartilage of growing long bone:

Histologically, there are some zone present in epiphyseal cartilage. These zone explain how a bone grow in length.

Zone of reserve No proliferation of chondrocytes

Zone of proliferation Chondrocytes undergo rapid mitosis under influence of growth hormone

Zone of  hypertrophy Chondrocytes stop mitosis, and begin to hypertrophy by accumulating glycogen, lipids, and alkaline phosphatase

Zone of cellular death Cartilagenous matrix begins to calcify- so chondrocytes do not get nutrition-- death of chondrocytes leaving empty spaces.--  Periosteal bud with Blood vessels begin to grow through the empty spaces

Zone of ossification Periosteal buds contain osteoblast which calcify the bone matrix and blood vessel form red bone marrow. This newly form zone of ossification add as metaphysis of growing long bone and bone increase in length

When grow of bone complete the zone of reserve begin to proliferate so whole epiphyseal cartilage converted into bone

Growing end of the long bone: the epiphysis which appear first and unit last with the diaphysis

The growing end is situated against the direction of the nutrient foramen

 Upper end of humerus and lower end of Radius and ulna is the growing end

Lower end of femus and upper end of tibia and fibula is the growing end

Clinical importance: injury or infection of this end makes the bone stunted in growth

Metaphysis : definition , clinical importance

 

Metaphysis: it is part of diaphysis near the epiphyseal cartilage found in growing long bone

Blood supply : it is supply by metaphyseal artery and internally by loop arteries branch of nutrient artery

Clinical importance of metaphysis

·       It is the most actively growing area of long bone

·       Profuse blood supply, contain hair pin loops like vessels so it is the common sites of infection  because hair pin loop like vessels make blood flow slow .

·       Muscle, ligament and capsule of joint are attached close to it

·       Metaphysis is common site of osteomyelitis in children

Periosteum : summary

 

Periosteum

It is a thick fibro-vasculo-cellular layer that covers the outer surface of bone except the articular surfaces which are covered by articular cartilage (hyaline cartilage). 

It consists of two layers:

Outer fibro vascular layer –is composed of collagen fibres and fibroblast  and blood vessels

Inner osteogenic layer – Inner cellular layer or osteogenic layer (containing osteoprogenitor cells which form osteoblasts).

It is united to the underlying bone by Sharpey’s fibers (collagen fibers).

It has very rich nerve supply and therefore it is the most pain sensitive part of bone.

Normally this layer responsible for increasing width of bone. By intramembranous ossification, it increase the width of bone  

 

Functions of periosteum

1.     It receives the  attachments of muscles

2.    Gives nutrition to the outer part of the compact bone by the periosteal vessels

3.    It is important in the repair of fractures

4.    During fetal development, this is responsible for appositional growth of bone

 Sharpey's fibers (bone fibers, or perforating fibres):  are a matrix of connective tissue consisting of bundles of strong collagenous fibres connecting periosteum to bone. They are part of the outer fibrous layer of periosteum, entering into the outer circumferential and interstitial lamellae of bone tissue