The palmar cutaneous branch of the median nerve branches off before the carpal tunnel. It innervates the middle of the palm. Ulnar nerve: The ulnar nerve comes from under the tendon of the flexor carpi ulnaris and runs through the ulnar tunnel (or tunnel of Guyon), which is between the pisiform and the hook of the hamate. The ulnar nerve and its dorsal cutaneous, palmar cutaneous, and superficial branches innervate the medial portion of the wrist and hand and the medial one and a half digits. Radial nerve: The radial nerve has two branches in the forearm: The deep branch runs through the posterior part of the forearm, supplying motor innervation to the extensor muscles. The superficial branch is a cutaneous nerve that runs under the brachioradialis muscle and passes through the anatomical snuff box, which is a visible depression formed near the base of the thumb by the tendons of the extensor pollicis longus and extensor pollicis brevis muscles. . The arteries and veins The ulnar and radial arteries carry blood down through the forearm into the wrist, where they anastomose (join together) to form arches. These arches, along with several branches, supply blood to the hand and digits.[9] Here are the arteries that enter the wrist: Anterior interosseous artery: This artery runs from the ulnar artery anterior to the interosseous membrane. It pierces the membrane distally to join the dorsal carpal arch. Palmar carpal branch: This branch runs from the ulnar artery over the anterior part of the wrist under the flexor digitorum profundus tendons. Dorsal carpal branch: This branch runs from the ulnar artery across the back of the wrist under the extensor tendons. Palmar carpal branch: This branch runs from the radial artery across the anterior wrist underneath the flexor tendons. Dorsal carpal branch: This branch runs from the radial artery across the wrist beneath the pollicis and extensor radialis tendons.
The function of CPU in PIC is same as a normal microcontroller CPU. A PIC CPU consists of several sub units such as instruction decoder, ALU, accumulator, control unit, etc. The CPU in PIC normally supports Reduced Instruction Set Computer (RISC) architecture (Reduced Instruction Set Computer (RISC), a type of microprocessor that focuses on rapid and efficient processing of a relatively small set of instructions. RISC design is based on the premise that most of the instructions a computer decodes and executes are simple. As a result, RISC architecture limits the number of instructions that are built into the microcontroller but optimizes each so it can be carried out very rapidly (usually within a single clock cycle.) . These RISC structure gives the following advantages. • The RISC structure only has 35 simple instructions as compared to others • The execution time is same for most of the instructions (except very few numbers). • The execution time required is very less (5 million instructions/second (approximately). Memory The memory in a PIC chip used to store the data and programs temporary or permanently. As like normal microcontrollers, the PIC chip also has certain amount of RAM,ROM,EEPROM,other flash memory, etc.[18] 4.9.1.4 Electrically Erasable Programmable ROM (EEPROM) The EEPROM is a special type of memory not contained in all microcontrollers. Its contents may be changed during program execution (similar to RAM ), but remains permanently saved even after the loss of power (similar to ROM). It is often used to store values, created and used during operation (such as calibration values, codes, values to count up to etc.), which must be saved after turning the power supply off. A disadvantage of this memory is that the process of programming is relatively slow. It is measured in miliseconds. ROM memory is used for permanent storage. The ROM memory also called as n program memory. A PI chip has certain amount of ROM memory. EEPROM memory is another category of ROM memory.. RAM memory is the one of the complex memory module in a PIC chip. This memory associated with various type of registers (special function registers and general purpose