Anatomy | Master Of Medicine

Category Archives: Anatomy

Layers of SCALP ,blood supply and nerve supply

SCALP has 5 layers and it can be memorized by a simple mnemonic SCALP

Layers of SCALP-Mnemonic

S -Skin

C-Connective tissue


L-Loose areolar tissue


Blood supply of scalp

The Internal carotid and External carotid artery which together give 5 branches to scalp.

Internal carotid artery

1.Supratrochlear artery- Supplies the midline of forehead.It is the branch of he ophthalmic branch of the internal carotid artery.

2Supraorbital artery- Supplies the lateral forehead and scalp as far up as the vertex. The supraorbital artery is a branch of the ophthalmic branch of the internal carotid artery.

External carotid artery

1.Superficial temporal artery- frontal and parietal branches of Superficial temporal artery supply much of the scalp

2.Occipital artery-supply  the posterior aspect of the scalp

3.Posterior auricular artery- It ascends behind the auricle to supply the scalp above and behind the auricle.

Nerve supply of scalp

1.Ophthalmic division of the Trigeminal nerve-via Supratrochlear nerve and the supraorbital nerve

2.Greater occipital nerve (C2)- Supplies the area posteriorly up to the vertex

3.Lesser occipital nerve (C2) -Supplies behind the ear

4. Maxillary division of the trigeminal nerve-Via zygomaticotemporal nerve supplies hairless temple

5.Mandibular division of the trigeminal nerve-Supplies via Auriculotemporal nerve

The mnemonic which can be used to learn the innervation of scalp is:


Zygomaticotemporal nerve

Greater occipital nerve

Lesser occipital nerve,

Auriculotemporal nerve

Supratrochlear nerve

Supraorbital nerve

Lymphatic drainage

Posterior half of the scalp drain to occipital and posterior auricular nodes. Anterior half drain to the parotid nodes,eventually draining into submandibular and deep cervical nodes.

Ventricles in the brain

What is a ventricle in the brain?

The ventricles of the brain are a communicating network of cavities filled with cerebrospinal fluid (CSF) and located within the brain parenchyma.

Which are the ventricles?

The ventricular system is composed of 2 lateral ventricles, the third ventricle, the cerebral aqueduct, and the fourth ventricle . The choroid plexuses located in the ventricles produce CSF, which fills the ventricles and subarachnoid space, following a cycle of constant production and reabsorption

 Where is the location of the ventricles?

  • 2 Lateral Ventricle- Lies in the cerebral cortex
  • 3rd ventricle-Lies between the two thalami
  • 4th Ventricle-Lies on the brain stem between medulla and cerebellum

Development of genital structures in males and females

Genital structures in males

  1. Genital tubercle -Glans penis
  2. Urogenital sinus  -Corpus spongiosum,Bulbourethral glands(Cowpers),Prostrate
  3. Urogenital folds -Ventral shaft of penis
  4. Labioscrotal swelling -Scrotum
  5. Gubernaculum -Gubernaculum testis
  6. Mesonephric/Wolffian duct -Epididymis,Ejaculatory duct,Ductus deferens
  7. Paramesonephric/Mullerian duct -Appendix of testis,prostatic utricle

Genital structures in females

  1. Genital tubercle – Glans clitoris
  2. Urogenital sinus -Greater vestibular glands of bartholin,Urethral and paraurethral glands of skene
  3. Urogenital folds -Labia minora
  4. Labioscrotal swelling -Labia majora
  5. Gubernaculum – Ovarian ligament and round ligament
  6. Wolffian duct – Duct of epoophoron
  7. Mullerian duct -Uterus,Fallopian tube,upper part of vagina


Derivatives of dorsal and ventral mesogastrium

The derivatives of dorsal and ventral mesogastrium are

Dorsal mesogastrium

  1. Greater omentum
  2. Gastrosplenic ligament
  3. Gastrophrenic ligament
  4. Lienorenal ligament

Ventral mesogastrium

  1. Lesser omentum
  2. Falciform ligament
  3. Coronary ligament
  4. Right and left triangular ligament

Diaphragm development

Septum transversum

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Diaphragm develops from the following components:

  1. Septum transversum
  2. Pleuroperitoneal membranes
  3. Ventral and dorsal mesenteries of esophagus
  4. Mesoderm of body wall
  5. Cervical myotomes

Septum transversum forms the central tendon of the diaphragm



Vertebral artery segments and branches

  1. Vertebral artery arises from the first part of Subclavian artery.
  2. Vertebral artery is the first and the largest part of Subclavian artery.

Divisions of vertebral artery

V1 segment - From origin to transverse process of C6 vertebra

V2 segment- Runs through foramen transversaria of upper six cervical vertebrae.

V3 Segment – Lies in the suboccipital triangle

V4 segment

  1. Extends from posterior atlanto occipital membrane to lower border of Pons.
  2. Traverses foramen magnum
  3. Pierces duramater, arachnoid mater and enters subarachnoid space.


Cervical branches- Spinal and muscular branches.

Intracranial branches

  1. PICA
  2. Medullary artery
  3. Anterior spinal artery
  4. Rarely Posterior spinal artery(Usually branch of PICA)


Intraperitoneal and retroperitoneal organs.

List of images in Gray's Anatomy: XII. Surface...

Image via Wikipedia

Intraperitoneal Organs

During development some organs grow inside the peritoneal cavity, these are called intra peritoneal organs

Retroperitoneal Organs

Some organs grow outside the peritoneal cavity, these are retroperitoneal organs


Secondary retroperitoneal organs

Some organs grow in the intraperitoneal space during fetal period but become extraperitoneal during later development.These organs are called Secondary retroperitoneal organs.

eg:Duodenum,pancreas,Ascending Colon,Descending colon.

Intraperitoneal organs

  1. Esophagus
  2. Stomach
  3. Jejunum
  4. Ileum
  5. Caecum
  6. Appendix
  7. Transverse colon
  8. Sigmoid colon

Extraperitoneal organs

  1. Duodenum
  2. Pancreas
  3. Ascending colon
  4. Descending colon
  5. Transverse colon

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