Ukindia Introductory medical topics

Anatomy

The body consists of head , neck , chest (thorax) , abdomen (belly) , shoulders , hips , upper and lower limbs , wrists and ankles , hands and feet .

Bones

The skull ends at the level of the ears and houses the brain . A long narrow tube called the vertebral column extends from the skull to the hips and contains an extension of the brain called the spinal cord.In the chest , ribs extend round from the vertebral column at the back and meet at the front to join the sternal bone to form a bony cage for the heart and lungs . A shoulder girdle of bones on each side connects the thorax to the upper arms , The upper arm bone is called the humerus and is linked to the lower arm bones called ulna and radius which are in turn linked to the wrist bones - 10 in each wrist . Distal(further from the center of the body ) to the wrist bones are the palm bones - metacarpals , five of them and each metacarpal is linked to the proximal finger bone . Distal to the proximal finger bone is the middle finger bone and distal to that is the distal finger bone .

The rib cage is linked to the upper arm by the shoulder girdle consisting of the collar bone in front and the flat scapula on the back .

Brain and nerves

The skull and vertebral column house the brain and its downward extension the spinal cord . The front of the brain forward of the ears and above the eyes is called the frontal lobe and is the thinking part of the brain. (Fig 1) Damage to this causes the patient to behave in an unsocial manner .Behind this is the part which deals with movement. A stroke in this area paralyses one side of the body . Behind that is the one which recieves sensation from all parts of the body and is called the parietal lobe . The part of the brain at the back of the skull is called the occiptal lobe and deals with sight . If hit by force at the back of the head damage to this part of the brain can cause permanent blindness even though the eyes are working .At the level of the ears are the temporal(ie at the temples) lobes which deal with hearing and memory . Behind it is the midbrain which wakes the rest of the brain up in the mornings and behind that is the cerebellum ( little brain) which deals with balance .

The brain and the spinal cord are linked to all organs in the body eg heart , lungs , eyes etc. by nerves . The brain has twelve pairs of these nerves called cranial nerves . Nerve 1 is sensory (takes messages from the sense organ to the brain) called the olfactory goes from the nose to the underside of the frontal lobe . It can be tested by making people sniff coffee or orange .Nerve 2 - the sensory optic nerve is a long one which goes from the eye to the back of the brain . The reason we see with the back of the brain is that originally in the sea the flat fish had eyes on top . When we came out of the sea and had to look forwards to see where we were going , the eyes had to migrate to the front to see and the nerve connecting to the back had to get longer. This nerve is tested by a chart on the wall

The 3rd 4th and 6th motor (taking messages from the brain to the muscles ) nerves called opthalmic , trochlear and abducens go to the muscles of the eye from the motor area of the brain . The opthalmic causes the eye to turn inwards , the trochlear twists it clockwise and the abducens turns it outwards . Holding a finger in front of the patients eye and asking him to hold the still and move the eyes with the movements of the finger test this nerve.

The 5th sensory nerve is a biggie and links the face to the sensory part of the brain behind the ears. It is tested by cotton wool swabs on the forehead , cheek and jaw with the eyes closed . The 7th nerve is motor and comes from the brains motor area to the face muscles . It splits into one part- the opthalmic to supply the forehead muscles so we can frown when we are not pleased , another called the maxillary to supply the cheeks and make us smile and a lower one called the mandibular for the jaw muscles to be clenched in anger . The patient is asked to move these areas of the face on command .

The 8th nerve in two parts - acoustic is from the ear and goes to the temporal lobe , one part is from the balance organs in the ear and is called the cochlear and the other is from the hearing organs in the ear .The auditory part is tested by whispering and the cochlear by putting cold water in the ears.The 9th nerve sensory is the glossopharyngeal for the throat . The tenth is sensory and brings messages from the heart , lungs and other parts. The 11th is motor and helps to shrug the neck . The last 12th is motor to the tongue and tested by asking the patient to stick his tongue out . It deviates to the damaged side.

Joints

Where one bone meets another eg the elbow- the arm bone and the forearm bone there has to be a small gap between them so that one can bend against the other . This gap is the joint . You can check out the major joints on the body by moving them yourself - the head and neck joint (atlanto-occipital) by nodding the head forwards and back , the neck and chest joint by twisting the neck left and right , the upper arm and lower arm joint ( humerus- ulna, radius) by bending (flexing) and straightening (extending) the elbow, the upper arm -wrist joint by flexing and extending the wrist , the wrist -palm joint by , the palm-finger joints by flexing and extending the fingers , the proximal finger -middle finger joint by flexing and extending the middle bone of the finger , the middle finger -distal finger joint .

On the abdomen the vertebral column - pelvis joint by twisting the hip , the pelvis- hip joint by flexing and extending the thigh , the thigh -lower leg (knee joint) by bending (flexing ) and straightening the joint , the lower leg -ankle joint , the ankle-foot joint , the foot - proximal toe joint and the middle toe joints .