GROSS ANATOMY OF SPLEEN

Shape of Spleen

The spleen is an ovoid, usually purplish, pulpy, soft, vascular (sinusoidal) mass about the size and shape of one's fist. The spleen is 1 inch thick, 3 inches wide, 5 inches long, and weighs 7 ounces.

HISTOLOGICAL FEATURES OF LYMPH NODE

Lymph Nodes

Lymph nodes are distributed throughout the body along the course of the lymphatic vessels. The nodes are found in the axilla and the groin, along the great vessels of the neck, and in large numbers in the thorax and abdomen, especially in mesenteries. Lymph nodes constitute a series of in-line filters that are important in the body's defense against microorganisms and the spread of tumor cells. All this lymph, derived from tissue fluid, is filtered by at least one node before returning to the circulation.

Gross Features of Lymph Nodes

Lymph nodes are elongated or kidney-shaped organs that have a convex surface that is the entrance site of lymphatic vessels and a concave depression, the hilum, through which arteries and nerves enter and veins and lymphatic vessels leave the organ (Figure- 1). A connective tissue capsule surrounds the lymph node, sending trabeculae into its interior.

LYMPHOID TISSUE: A BRIEF OUTLINE

The body has a system of cells—the immune system—has the ability to neutralize or inactivate foreign molecules (such as soluble molecules as well as molecules present in viruses, bacteria, and parasites) and to destroy microorganisms or other cells (such as virus-infected cells, cells of transplanted organs, and cancer cells).

The cells of the immune system have following general characteristics:

1.      They are distributed throughout the body in the blood, lymph, and epithelial and connective tissues;

2.      They are arranged in small spherical nodules called lymphoid nodules found in connective tissues and inside several organs and

3.      They are organized as differently sized organs called lymphoid organs— like the lymph nodes, the spleen, the thymus, and the bone marrow.

a.      Spleen and thymus are called primary or central lymphoid organs.

b.      Lymph nodes, spleen and other lymphoid tissues line tonsil are called secondary or peripheral lymphoid organs.

MUSCLES OF RESPIRATION

Respiration involves Inspiration and Expiration which are accompanied by the alternate increase and decrease of the volume of thoracic cavity. 

Inspiration is an active process and is achieved by increase in all diameters of thoracic cavity. (Thoracic cavity has three diameters – vertical, transverse and anteroposterior.)

The muscles involved in inspiration are:

Diaphragm:

Diaphragm is the primary muscle of inspiration.It increases all the three diameters of thorax.

GROSS ANATOMY AND HISTOLOGICAL FEATURES OF THYROID GLAND

The thyroid is a highly vascular ductless gland found deep in the neck region and overlapped by the anterior neck muscles.

Location of the thyroid gland:

It situated in front and at the sides of trachea opposite 5th, 6th, 7th cervical and 1st thoracic vertebrae in the neck region.

Intrinsic or Deep or Paraspinal Muslces of Back: Brief Outline

What are Paraspinal Muscles or Deep Muscles or Intrinsic Muscles of back?

These are deep or intrinsic back muscles. These muscles form a prominent mass on each side of the spinal column extending from base of the skull to the sacrum. These muscles consists of many separate, overlapping muscles of different lengths, attached to the spinous or transverse processes of different vertebrae. 

Cranial Dura Mater and Dural Venous Sinuses

Objectives:

Describe the features (and reflections/foldings) of cranial dura mater.

Describe the intracranial dural venous sinuses.

The brain is covered from outside inwards by three meningeal layers namely

                  

i)         Dura mater

ii)       Arachnoid mater and

iii)     Pia mater.

Dura Mater:

 It is tough and consists of

outer endosteal/periosteal layer which serves as inner periosteum (covering inside of the bones that form the calvaria of skull) and

inner meningeal layer which is a strong fibrous membrane that is continuous at the foramen magnum with the spinal dura mater covering the spinal cord.

Muscles of the Eye-lid: Actions and Innervations

Objective

Describe the muscles of eye lid, their actions and innervations.

Muscles of eyelid: Their Actions and Innervations

            The muscles of the eyelids are:

Levatorpalpebræsuperioris (LPS)

Orbicularis oculi

Corrugator

 

Extra-ocular Muscles of Eye: their attachment, actions and nerve supply

Objectives:

Describe the attachment of extra-ocular muscles.

Describe the action and nerve supply of extra-ocular muscles.

Extra-ocular muscles of eye

The muscle acting on the eye ball to produce various movements of eye are called extr-aocular muscles which consists of

Four recti	Two oblique muscles
Superior rectus	Superior oblique
Inferior rectus	Inferior oblique
Medial rectus
Lateral rectus

Perineum: Boundaries, divisions, perineal fascia and perineal pouches

Perineum

The perineum refers to the areas both externally on the surface and internally as a shallow compartment of the body. The compartmental area of perineum lies inferior to the pelvic outlet and is separated from the main pelvic cavity by the pelvic diaphragm. In other words the pelvis is divided into main pelvic cavity above and perineum below by the pelvic diaphragm.

Joints of Pectoral Girdle: Anatomy of Shoulder Joint, Acromioclavicular Joint and Sternoclavicular Joint

Pectoral Girdle

Pectoral Girdle or Shoulder Girdle connects the free part of the upper limb with the trunk. It consists of scapula and clavicle on each side. A series of anatomical organization makes the girdle extremely mobile. The mobility of scapula is essential for free movement of upper limb. The clavicle acts as a strut which holds the scapula laterally allowing the upper limb to swing freely from the side of the trunk. 

Gross anatomy and histological features of Pituitary Gland

What is pituitary gland?

Also known as hypophysis cerebri, pituitary is an ovoid neuroglandular organ.

It is suspended from the floor of the third ventricle by a stalk known as infundibulum.

It is located in a depression called hypophyseal fossa of sella turcica of body of sphenoid. The fossa is roofed by the diaphragm sellae which is a fold derived from the meningeal layer of dura mater. The diaphragm sellae is pierced by the pituitary stalk or infuldibulum.

Gross Anatomy of Urethra

This note briefly describes about the gross anatomy of male and female  urethra along with its blood supply, lymphatic drainage and innervation.

General Consideration

Urethra is the terminal part of the urinary tract and conducts urine from bladder to exterior.

Male urethra and female urethra are considered separately below.

MALE URETHRA

•         Muscular tube

•         18-20 cm long

•         Extends from internal urethral orifice of the urinary bladder to the external urethral orifice at the tip of the glans penis

•         also acts as the part of genital tract by providing a passageway for semen during ejaculation.

PORTAL VEIN ANATOMY : FORMATION, TRIBUTARIES and PORTOCAVAL ANASTOMOSIS

This note describes the formation, tributaries and major site for the portocaval anastomosis (also called portosystemic anastomosis or portal-systemic anastomosis).

Portal Vein

The portal vein is the vein of the gut that drains blood from the abdominal part of the gastrointestinal tract from the lower third of esophagus to halfway down the anal canal including spleen, pancreas and gall bladder.

Formation

It is about 2 inches long and formed by the union of superior mesenteric vein and splenic vein behind the neck of the pancreas. It ascends to the right behind the first part of the duodenum and enters the free margin of the lesser omentum. Entering through the porta hepatis, it divides into right and left terminal branches which further break up into sinusoids. The blood from the sinusoids is collected by hepatic veins that join the inferior vena cava.

Hepatobiliary Apparatus: Gross Anatomy of Liver and Gallbladder

Hepatobiliary System

Liver

The liver is the largest of the abdominal viscera and occupies a substantial portion of the upper abdominal cavity. It is an essential organ that performs a wide range of metabolic activities required for homeostasis, nutrition and immunity. It is mainly composed of epithelial cells (hepatocytes) originating from the endoderm of primitive foregut. These cells are bathed in blood derived from the hepatic portal veins and hepatic arteries, thereby facilitating continuous chemical exchange between the cells and the blood. Hepatocytes are also associated with an extensive system of minute canals, which form the biliary system into which products are secreted.