The human body is a complex machine that functions through the harmonious, collaborative working of different systems within. Medical professionals across the globe are taught about the location, importance, and function of these systems.
With advanced medical care facilities, there are many more professionals (besides doctors, nurses and other medical staff) performing crucial duties. The IT professionals of a hospital; analysts from the radiology department, and those undergoing PACS (Picture Archiving and Communication System) training ought to know about the structure and function of the human body.
In this course module, we shall briefly discuss the medical anatomy of the body for an audience of IT and other non-medical professionals in a healthcare setting.
The average human body is divided into different organ systems that have specified anatomical identities and roles. The major anatomical divisions of systems are discussed below:
The skeletal system is the basic structure of the body. It provides support and allows movement (locomotion). The skeletal system allows for the erect standing posture and also aids in protecting the soft vital organs.
As the skeletal system comprises 20% of the body weight, it is important to know about the important landmarks while diagnosing abnormalities.
The different structures that make up this system include:
To better understand the skeletal system it is broken down into two divisions namely axial and appendicular skeleton.
The axial skeleton has a total of 80 bones. The skeleton makes up the vertical axis of the body. The skull is composed of a fusion between cranial and facial bones.
The vertebral column has 24 vertebrae divided into three different regional segments i.e. cervical (7) in the head/neck, thoracic (12), lumbar (5) and then we have sacrum and the tail bone (cocyx).
Attached to the upper part of the spine is the thoracic cage formed by 12 pairs of ribs and a thick, dense breastbone i.e. sternum.
Small auditory ossicles (6 bones) and a U-shaped hyoid bone are also part of the axial skeleton. The auditory bones are miniature structures aimed at sound transmission while the hyoid serves as an attachment point for soft tissues in the neck.
The 126 bones of the appendicular skeleton attach to the axial skeleton forming the arms and legs (limbs).
The collarbone (clavicle) and the shoulder blade (scapula) join together to form the pectoral girdle on both sides to which the bones of the upper limb are attached.
Upper limb bones include the humerus (long bone in the upper arm), radius and ulna(long bones of the forearm). 8 small wrist bones known as carpals to which 5 metacarpals are attached. The metacarpals form the middle portion of the hand to which the fingers are attached (14 bones known as phalanges).
Just like the pectoral girdle, there is a pelvic girdle that forms the hip region. Ilium, ischium (curved bone), and pubis join to form the pelvic girdle which serves as an attachment point for the lower limbs.
The lower limb has a large bone femur (in the upper leg) which is attached tibia and fibula (bones of the lower leg). The patella or knee cap covers the converging bones of the upper and lower leg.
7 tarsal bones constitute the ankle to which 5 metatarsals are attached (forming the middle area of the foot). Just like the hand, you get 14 bones (phalanges) that comprise the toes.
The muscular system is as crucial as the skeletal system because without these soft tissues structures the body is useless. Based on their composition and anatomy the muscular system is divided into 3 main types:
These muscles attach to the skeleton (forming the musculoskeletal system) and bring about voluntary movements. These striated muscles are made up of numerous bundles of muscle fibers that are mainly protein in nature.
Muscles present in different areas are specialized to perform specific roles. Based on the region we get muscles of the head/neck (muscles of mastication, pharynx, etc.), trunk and back muscles, abdominal muscles, limb muscles.
These muscles line up the walls of the blood vessels. These elastic are also present in the hollow organs. Smooth muscles are flexible in nature and not under voluntary control.
The muscles of the heart are distinct from the other two. This is the most efficient muscle of the whole body. It is under the control of the autonomic nervous system (involuntary control).
The integumentary system comprises several organs including skin (the largest gland of the body), and associated structures i.e. hair, nails, appendages, and glands.
The lymphatic system is a dense network of lymph vessels with nodes and ducts that run throughout the body. The lymphatic system has specialized structures called lacteals present in the walls of the small intestine.
The lymph channels are present in the whole body. Special structures called lymph nodes are present in different locations including the mandible, neck, armpits, and groin. You can find lymph nodes in the chest and abdominal region too.
Structures associated with the lymphatic system are tonsils (in the oral region), spleen (in the abdomen), and thymus gland (present behind the sternum i.e. chest bone).
The lymphatic system builds plasma cells, lymphocytes and monocytes which provides immunity to the body. The lymph nodes filter fluid that passes through where immune cells fight against disease and infection. The nodes also drain excess fluids from the body.
The nervous system is the CPU of the body and controls all voluntary and involuntary actions done in one’s life. The main organ of this system is the brain that sits in the cranium (skull). The brain is connected to another important processor i.e. the spinal cord via a network of live wires called nerves or neurons.
The brain and the spinal cord are collectively known as the central nervous system (CNS) which is the command and control center of the body. The conduit between the CNS and the rest of the body is known as the peripheral nervous system which is further divided into autonomic (ANS) and somatic (SNS) nervous systems.
A nerve cell consists of cell body, axons (extensions that transmit impulses), and dendrites or dendrons that receive nerve impulses. The human body is replete with nerves that innervate everything from muscles, to glands and bones, however, there are differences in the direction of nerve impulse conduction.
Afferent neurons carry impulses from peripheral tissues towards the CNS while the efferent neurons carry messages from the CNS to the body.