anatomy made easy

MEDIASTINUM:
space between 2 pleural sacs
Boundaries:
Superior – Root of the neck, Thoracic inlet
Inferior – Diaphragm
Anterior – Sternum and Costal cartilages
Posterior – Bodies of the 12 Thoracic vertebra
Divisible into:
Superior:
-------------- imaginary plane passing from Sternal angle of Louie anteriorly to the lower border of the body of 4th Thoracic vertebra
Inferior:
Subdivided into:
Anterior
Middle
Posterior

CONTENTS:
Superior mediastinum: remains of Thymus gland, SVC, Brachiocephalic art/vein, Left CCA, Left Subclavian art, Arch of Aorta, Phrenic and Vagus N, Left Recurrent Laryngeal N, Trachea, Esophagus, Thoracic duct, Lymph nodes, Sympathetic trunk
Anterior mediastinum: remains of Thymus gland, Sternopericardial ligament, LN

Middle mediastinum: Heart, Pericardium, Roots of great blood vessels, LN, Phrenic N, Bifurcation of Trachea

Posterior mediastinum: Descending thoracic aorta, Esophagus, Thoracic duct, Azygous and Hemiazygous veins, Vagus N, Splanchnic N, LN, Sympathetic trunk

PERICARDIUM:
double walled fibro-serous sac that encloses the heart and the roots of great blood vessels; located Posteriorly to the body of sternum and 2nd to 6th costal cartilages and Anteriorly to T5 – T8 vertebrae
Fibrous Pericardium: tough fibrous tissue, limits unnecessary movements of the heart
Serous Pericardium:
Parietal layer – closely adherent to fibrous pericardium
Visceral layer – closely adherent to heart; equivalent to Epicardium in Histology
Pericardial cavity – potential space between Parietal and Visceral layers of Serous Pericardium containing a small amount of fluid (30 ml) to prevent friction
PERICARDITIS – inflammation of the pericardium; causes severe Substernal pain and produces Pericardial effusion – if the effusion is extensive, excess fluid may interfere with the action of the heart by compression – results to Cardiac tamponade; inflammation causes the surfaces to become rough and the resulting friction between the 2 layers maybe detected during auscultation – Friction Rub

HEART:
Normal weight – Males – 280 – 340 gms
Females – 230 – 280 gms
Base – formed by Left Atrium
Apex – Left Ventricle; Apex beat – 5th ICS LMCL (7 to 9cm from median plane)
Surfaces- Sternocostal / Anterior – Right Ventricle
Diaphragmatic / Inferior – Both Ventricles, mainly Left
Pulmonary / Left – Left Ventricle
Borders – Right border – Right Atrium
Inferior border – Both ventricles, mainly Right
Left border – Left Ventricle
Superior border – Right / Left Auricles
RIGHT ATRIUM:
Receives blood from: SVC
IVC
Coronary sinus
Anterior Cardiac vein
Vena cordis minimae
Internal wall – Musculi pectinati – rough anterior portion
Sinus venarum – posterior part; presence of oval
Depression – Fossa ovalis (site of Foramen
Ovale); if persists after birth – leads to ASD
RIGHT VENTRICLE:
- Thicker wall than the R atrium
- Internal surface with irregular muscular ridges called Trabeculae Carnae
where Papillary muscle originates; apices are connected to the valve by
fibrous strands called as Chordae tendinae
Moderator Band – modified Trabeculae carnae that crosses the
Interventricular septum
LEFT ATRIUM:
- Receives the Pulmonary veins
- Thicker wall compared with Right Atrium
LEFT VENTRICLE:
Thicker wall than R ventricle
Conical cavity longer than Right
Trabeculae carnae finer and more numerous than Right
Papillary muscles are larger than Right
AUSCULTATORY AREAS FOR HEART VALVES:
TRICUSPID – Lower end of the sternum
PULMONARY – 2nd Left ICS
MITRAL – 5th ICS Left MCL
AORTIC – 2nd Right ICS
HEART SOUNDS:
1st – produced by closure of Tricuspid and Mitral valves
2nd – produced by closure of Aortic and Pulmonary valves
BLOOD SUPPLY OF THE HEART:
from ascending aorta
Right Coronary
Marginal
Posterior interventricular
Left Coronary
Anterior interventricular
Circumplex
VENOUS DRAINAGE OF THE HEART:
mainly by Coronary Sinus which opens into the Right Atrium
Receives the: Great Cardiac vein
Small Cardiac vein
Middle Cardiac vein
Anterior cardiac vein and Vena cordis minimae – partly drains blood and directly into the Right atrium
Branches of Coronary arteries are END arteries – if there is sudden occlusion of a major branch, the region supplied by the occluded branched becomes INFARCTED and soon will undergo NECROSIS – leads to MYOCARDIAL INFARCTION
3 MOST COMMON SITES OF CORONARY OCCLUSION
Anterion Interventricular artery
Right Coronary
Circumplex artery
Most common cause of Ischemic heart disease is Coronary Insufficiency resulting from ATHEROSCLEROSIS of Coronary arteries.
NERVE SUPPLY OF THE HEART:
innervated by sympathetic and parasympathetic fibers of the autonomic nervous system via the cardiac plexuses
SKELETAL SYSTEM:
Total number of Bones: 206 AXIAL = 80
APPENDICULAR = 126 (64 upper; 62 lower)
AXIAL SKELETON:
SKULL – 22
PAIRED UNPAIRED
CRANIAL - Parietal Frontal
Temporal Occipital
Sphenoid
Ethmoid
FACIAL Palatine Vomer
Lacrimal Mandible
Maxilla
Nasal
Inferior Nasal Concha
Zygomatic
OSSICLES – 6
Malleus = Hammer
Incus = Anvil
Stapes = Stirrups
HYOID – 1
VERTEBRAL COLUMN – 26
Cervical = 7
Thoracic = 12
Lumbar = 5
Sacrum = 1
Coccyx = 1
Primary Curvature – CONCAVE VENTRALLY; Thoracic and Sacral
Secondary Curvature – CONVEX VENTRALLY; Cervical and Lumbar
STERNUM – 1
Manubrium , Body and Xiphoid process
Sternal angle of Louie = at level T4
= costal cartilage of 2nd rib is attached
RIBS – 24
TRUE / VERTEBROSTERNAL – 1st to 7th
FALSE / VERTEBROCHONDRAL – 8th to 12th
False rib proper – 8th to 10th
Floating rib – 11th and 12th
APPENDICULAR SKELETON:
Upper extremity – 64
Shoulder girdle – Clavicle -2
Scapula -2
Humerus -2
Radius -2
Ulna -2
Carpals – 16
PROXIMAL row – Scaphoid / Navicular
Lunate
Triquetral
Pisiform
DISTAL row - Trapezium
Trapezoid
Capitate
Hamate
Metacarpals – 10
Phalanges – 28
Lower extremity – 62
Hip bone – 2 (Ilium, Ischium, Pubis)
Femur – 2
Patella -2
Tibia – 2
Fibula – 2
Tarsals – 14
Calcaneus
Talus
Navicular / Scaphoid
Cuboid
Cuneiform - 3
Metatarsals – 10
Phalanges – 28
JOINTS:
Basis of classification:
Mobility
Medium that connects it
Types of Joints:
SYNARTHROSIS – united by a Fibrous tissue
Suture – Coronal and Sagittal sutures in skull
Syndesmosis – Interosseous membranes
Gomphosis – articulation between a tooth and alveolar socket of maxilla or mandible
AMPHIARTHROSIS – united by a Cartilage
Synchondrosis / Primary Cartilagenous joint – Hyaline cartilage
Symphysis / Secondary Cartilagenous joint – Fibrocartilage
DIARTHROSIS – Synovial
characterized by the presence of a joint cavity covered with an articular capsule; synovial membranes lining the capsule secrete fluid to lubricate the joint
TYPES
Plane – flat for gliding / sliding movements ex. Sternoclavicular and Acromioclavicular joints
Ball and Socket / Enarthrosis – Multiaxial joint ex. Shoulder and Hip joints
Hinge / Ginglymus – for Flexion and Extension movements ex. Knee, Elbow and Ankle joints
Pivot / Trochoid – for Rotation ex. Atlantoaxial joint
Condyloid – for Flexion / Extension; Adduction / Abduction ex. Metacarpophalangeal / Knuckle joint
Saddle – for Flexion / Extension; Adduction / Abduction ex. Carpometacarpal joint
MUSCLES OF THE GLUTEAL REGION
ACTION
NERVE SUPPLY
Gluteus Maximus
Extension of Thigh
Inferior Gluteal
Gluteus Medius *
Gluteus Minimus
Abduction of Thigh
Medial Rotation
Superior Gluteal
Piriformis
Obturator internus
Sup / Inf Gemellus
Quadratus femoris
Lateral Rotation
Waddling gait – as a result of Superior Gluteal nerve injury; weakened abduction of the thigh by Gluteus medius muscle – (+) Trendelenberg sign
MUSCLES OF THE THIGH
ACTION
NERVE SUPPLY
ANTERIOR GROUP
Iliopsoas
Tensor Fascia Lata
Sartorius
Quadriceps femoris *
Flexion of Thigh
Extension of Leg
Femoral
MEDIAL GROUP
Pectineus *
Adductor Longus
Adductor Brevis
Adductor Magnus *
Gracilis
Adduction of Thigh
Obturator
POSTERIOR GROUP
( Hamstring muscles)
Semitendinosus
Semimembranosus
Biceps femoris
Flexion of Leg
Extension of Thigh
Sciatic
Quadriceps femoris – Rectus femoris, Vastus lateralis, Vastus intermedius and Vastus medialis
Pectineus – Adducts and Flexes Thigh, supplied by Femoral nerve
Adductor magnus – 2 parts : Adductor and Hamstring
FEMORAL TRIANGLE:
- Boundaries: Superiorly – Inguinal ligament
Medially – Adductor longus
Laterally – Sartorius
Base – Inguinal ligament
Apex – Sartorius and Adductor longus
Floor – Adductor longus, Pectineus, Iliopsoas
Roof – Fascia Lata
- Contents: 1. Femoral vein
2. Femoral artery
3. Femoral nerve – L2,L3,L4
4. Femoral sheath
5. Lymph nodes
MUSCLES OF THE LEG
ACTION
NERVE SUPPLY
ANTERIOR GROUP
Tibialis anterior *
Extensor hallucis longus
Ext. digitorum longus
Peroneus tertius *
Dorsiflexion of Foot
Deep Peroneal *
LATERAL GROUP
Peroneus longus
Peroneus brevis
Plantarflexion and
Eversion of Foot
Superficial Peroneal *
POSTERIOR GROUP
Gastrocnemius
Soleus
Plantaris
Popliteus
Flexor hallucis longus
Flexor digitorum longus
Tibialis posterior *
Plantarflexion of Foot
Tibial *
SCIATIC NERVE – L4 to S3 ; 2 terminal branches – TIBIAL
COMMON PERONEAL
FOOT DROP – due to injury to Common Peroneal nerve
Peroneus muscles ( tertius, longus & brevis ) – Eversion of Foot
Tibialis anterior and posterior – Inversion of Foot
INTRINSIC MUSCLES OF THE SHOULDER
ACTION
NERVE SUPPLY
Supraspinatus*
Abduction of arm
Suprascapular
Infraspinatus*
Lateral rotation of arm
Suprascapular
Teres minor*
Lateral rotation of arm
Axillary
Subscapularis*
Medial rotation of arm
Upper Subscapular
Deltoid
Abduction
Axillary
ROTATOR CUFF MUSCLES – stabilizes the shoulder joint on it’s anterior, posterior and superior parts. WEAKEST on the inferior portion – common dislocation of shoulder joint
MUSCLES OF THE ARM
ACTION
NERVE SUPPLY
Biceps Brachii
Flexor of Elbow joint
Supinator of Forearm
Musculocutaneous
Coracobrachialis
Flexion and Adduction of arm
Musculocutaneous
Brachialis
Main Flexor of Elbow joint
Musculocutaneous
Triceps Brachii
Main Extensor of Elbow joint
Radial
MUSCLES OF THE FOREARM
ACTION
NERVE SUPPLY
ANTERIOR GROUP *
Pronator teres
Flexor carpi radialis
Palmaris longus
Flexor carpi ulnaris *
Flexor digitorum superficialis
Flexor digitorum profundus *
Flexor pollicis longus
Pronator quadratus
FLEXION
Median
POSTERIOR GROUP *
Brachioradialis *
Ext. carpi radialis longus
Ext. carpi radialis brevis
Ext. digitorum
Ext. digiti minimi
Ext. carpi ulnaris
Anconeus
Supinator
Abductor pollicis longus
Ext. pollicis brevis
Ext. pollicis longus
Ext. indicis
EXTENSION
Radial
All muscles of Anterior aspect of Forearm supplied by Median nerve EXCEPT Flexor carpi ulnaris and medial half of Flexor digitorum profundus – supplied by Ulnar nerve
All muscles of Posterior aspect of Forearm are Extensors EXCEPT Brachioradialis which is a Flexor
LATERAL EPICONDYLITIS / ELBOW TENDONITIS – inflammation of the lateral epicondyle ( common origin of extensor muscles ); repetitive forceful Pronation - Supination of the forearm leads to “TENNIS ELBOW”
ANATOMICAL SNUFF BOX:
Boundaries – Anteriorly: tendons of APL and EPB
Posteriorly: tendon of EPL
Floor: Scaphoid and Trapezium
BRACHIAL PLEXUS – formed by union of ventral rami of C5 to T1
Branches from roots
Dorsal scapular – Rhomboids
Long thoracic – Serratus anterior
Branches from upper trunk
Suprascapular – Supraspinatus and Infraspinatus
Nerve to Subclavius
Branches from lateral cord
Lateral pectoral – Pectoralis major
Musculocutaneous – Coracobrachialis, Brachialis, Biceps brachii
Lateral half of Median – Flexor muscles of forearm
Branches from medial cord
Medial pectoral – Pectoralis minor
Medial brachial cutaneous nerve
Medial antebrachial cutaneous nerve
Ulnar – Intrinsic muscles of hand
Medial half of Median – Flexor muscles of forearm
Branches from posterior cord
Upper subscapular – Subscapularis
Thoracodorsal – Latissimus dorsi
Lower subscapular – Teres major
Axillary – Deltoid and Teres minor
Radial – Extensor muscles of upper limb
UPPER BRACHIAL PLEXUS INJURY:
due to excessive separation of neck and shoulder or may result from violent stretching of an infant’s neck during a difficult delivery
ERB – DUCHENES PARALYSIS
Characteristic position – WAITER”S TIP ; limb hangs by the side in medial position and forearm is pronated
LOWER BRACHIAL PLEXUS INJURY:
due to traction injury as in excessive abduction of arm; ex. Forceful pull of the infants upper limb during delivery
ULNAR NERVE INJURY
Impairment of wrist flexion and movements of intrinsic muscles of the hand – CLAW HAND DEFORMITY
LONG THORACIC NERVE INJURY:
caused by blows or surgical injury to the nerve in axilla; ex. Weight lifting or carrying a heavy object on the shoulder for a long time
paralysis of Serratus anterior muscle
medial border and inferior angle of scapula to become unusually prominent – WINGED SCAPULA
AXILLARY NERVE INJURY:
due to inferior dislocation of the shoulder joint or fracture of the surgical neck of the humerus
wasting and atrophy of Deltoid muscle; results to weakened abduction of the shoulder
RADIAL NERVE INJURY:
due to fracture of the midshaft of the humerus
inability to extend wrist and fingers
WRIST – DROP
MEDIAN NERVE INJURY:
due to supracondylar fracture of the humerus
compression of median nerve at Carpal tunnel
Muscles of the Thenar eminence are paralyzed and wasted; thumb is laterally rotated
APE – LIKE HAND
ULNAR NERVE INJURY:
due to fracture of the medial epicondyle of the humerus
inability to adduct and abduct the fingers
CLAW – HAND
LATERAL EPICONDYLITIS / TENNIS ELBOW:
inflammation of the common extensor tendon – lateral epicondyle
MEDIAL EPICONDYLITIS / GOLFER’S ELBOW:
inflammation of the common flexor tendon – medial epicondyle
PLEURA: 2 parts:
PARIETAL LAYER – lines the thoracic wall
VISCERAL LAYER – covers the outer surfaces of the lungs
2 layers are separated from one another by a slit-like space called as Pleural cavity which normally contains a small amount of fluid
Nerve supply:
Parietal layer is sensitive to Pain, Temperature, Pressure and Touch
Costal part – Intercostal nerve
Mediastinal part – Phrenic nerve
Diaphragmatic part – Phrenic and Lower intercostals nerve
Visceral layer is sensitive to Stretch; from pulmonary plexus
COSTAL LINE of Pleural reflection passes obliquely across the:
8th rib in MCL
10th rib in MAL
12th rib in sides of vertebral column
LOWER MARGIN of Lungs cross the:
6th rib in MCL
8th rib in MAL
10th rib in sides of vertebral column
PLEURISY /PLEURITIS:
inflammation of pleura secondary to inflammation of lung ex. Pneumonia
results in the pleural surfaces becoming coated with exudates causing the surface to be rough – produces friction – PLEURAL RUB
LUNGS:
RIGHT
LEFT
Larger,heavier,shorter,wider
Smaller,lightier,longer,narrower
Lobes
Superior,Middle & Inferior
Superior & Inferior
Fissures
Horizontal and Oblique
Oblique
BRONCHOPULMONARY SEGMENTS:
anatomical, functional and surgical unit of lung
subdivision of lung lobe
pyramidal in shaped; apex directed towards the lung root
surrounded by connective tissue
supplied by it’s own bronchus, receives an artery, vein, lymph vessels
RIGHT LUNG
LEFT LUNG
Superior lobe
Apical
Posterior
Anterior
Apical
Posterior
Anterior
Superior Lingular
Inferior Lingular
Middle lobe
Lateral
Medial
Inferior lobe
Superior / Apical
Anterior Basal
Medial Basal
Lateral Basal
Posterior Basal
Superior / Apical
Anterior Basal
Medial Basal
Lateral Basal
Posterior Basal
Blood supply of Lungs:
Bronchial artery – from descending aorta
Pulmonary artery
Venous drainage:
Bronchial vein – drains into Azygous and Hemiazygous veins
Pulmonary vein
Nerve Supply:
From pulmonary plexus which is formed from branches of the sympathetic trunk and receives parasympathetic fibers from Vagus nerve.
Sympathetic efferent fibers produce Bronchodilatation and Vasoconstriction
Parasympathetic efferent fibers produce Bronchoconstriction and Vasodilatation; and increase glandular secretion.
AORTA:
Ascending Aorta
R / L Coronary
Arch of Aorta
Brachiocephalic
Left CommonCarotid
Left Subclavian
Descending / Thoracic Aorta
Posterior intercostals
Subcostal
Pericardial
Esophageal
Bronchial
Mediastinal
Abdominal Aorta
Descending / Thoracic Aorta enters the Aortic Hiatus at level T-12 to become Abdominal aorta
COMMON CAROTID: Right from Brachiocephalic; Left from Arch of Aorta
External Carotid
Superior Thyroid
Ascending Pharyngeal
Lingual
Facial
Occipital
Posterior Auricular
Superficial Temporal
Maxillary
Internal Carotid
Opthalmic
Posterior communicating
Anterior cerebral
Middle cerebral
SUBCLAVIAN ARTERY: Right from Brachiocephalic; Left from Arch of Aorta
divided into three / 3 parts by Scalenous anterior muscle
1. First part – Vertebral
Thyrocervical
Internal thoracic
2. Second part – Costocervical trunk
3. Third part
AXILLARY ARTERY:
begins at the lateral border of 1st rib as a continuation of the subclavian artery; and at the lower border of Teres major muscle it becomes the Brachial artery
divided into three / 3 parts by Pectoralis Minor muscle
1. First part – Highest Thoracic
2. Second part – Thoraco-acromial
Lateral thoracic
3. Third part – Subscapular
Anterior Circumplex humeral
Posterior Circumplex humeral
ABDOMINAL AORTA:
Branches:
1. Anterior Visceral ( Unpaired) – Celiac
Superior mesenteric
Inferior mesenteric
2. Lateral Visceral ( Paired) – Suprarenal
Renal
Testicular / Ovarian
3. Lateral Parietal ( Paired) – Inferior Phrenic
Lumbar
4. Terminal branches – R / L Common Iliac
Median Sacral
INTERNAL JUGULAR VEIN:
drains blood from brain, face and neck regions
continuation of Sigmoid sinus
Receives the – Facial
Pharyngeal
Lingual
Superior Thyroid
Middle Thyroid
BRACHIOCEPHALIC / INNOMINATE VEIN:
union of Internal jugular and Subclavian veins
at the level of the inferior border of the 1st Right costal cartilage, the 2 Brachiocephalic veins unite to form the Superior vena cava
Receives the – Internal thoracic
Vertebral
Inferior thyroid
Superior intercostals
SUPERIOR VENA CAVA:
union of R and L Brachiocephalic veins
ends at the level of the 3rd costal cartilage to enter the Right Atrium
AZYGOUS VEIN:
connects SVC from IVC
Receives the – Lower intercostals veins
Mediastinal
Esophageal
Bronchial
Hemiazygous
Accessory Hemiazygous
Azygous, Hemiazygous and Accessory Hemiazygous system offers an alternate means of venous drainage from the thoracic, abdominal and back regions when there is obstruction to IVC