transcript/DIY_zyl6eoU-3Rg.txt

[0.000 --> 9.000]  Few structures of the human anatomy are as unique as the hand.
[9.000 --> 13.560]  The hand needs to be mobile in order to position the fingers in thumb.
[13.560 --> 18.480]  The hand must have adequate strength to grip objects firmly, but must also be coordinated
[18.480 --> 22.200]  to perform fine motor tasks with precision.
[22.200 --> 26.800]  The important structures of the hand can be divided into several categories.
[26.800 --> 37.360]  These include bones, joints, ligaments, tendons, muscles, nerves, and blood vessels.
[37.360 --> 41.800]  Let's define some common anatomic terms as they relate to the hand.
[41.800 --> 46.160]  This will make it clearer as we talk about the structures of the hand later.
[46.160 --> 51.480]  The front or palm side of the hand is referred to as the palm or side.
[51.480 --> 55.520]  The back of the hand is called the dorsal side.
[55.520 --> 60.480]  The half of the hand from the middle finger to the thumb is called the radial side.
[60.480 --> 66.640]  The other half is called the ulnar side.
[66.640 --> 70.400]  There are 27 bones within the wrist and hand.
[70.400 --> 74.800]  The wrist itself contains 8 small bones called carpals.
[74.800 --> 81.640]  The carpals join with the two forearm bones, the radius and ulna, forming the wrist joint.
[81.640 --> 85.600]  After into the palm, the carpals connect to the metacarpals.
[85.600 --> 89.280]  There are 5 metacarpals forming the palm of the hand.
[89.280 --> 93.800]  One metacarpal connects to each finger and thumb.
[93.800 --> 99.520]  Small bone shafts call phalanges line up to form each finger and thumb.
[99.520 --> 104.920]  The main knuckle joints are formed by the connections of the phalanges to the metacarpals.
[104.920 --> 110.640]  These joints are called the metacarpal phalangial joints, or MCP joints.
[110.640 --> 116.720]  The MCP joints work like a hinge when you bend and straighten your fingers and thumb.
[116.720 --> 122.960]  The three phalanges at each finger are separated by two joints, called interphalangial joints
[122.960 --> 125.040]  or IP joints.
[125.040 --> 132.240]  The one closest to the MCP joint is called the proximal IP joint or the PIP joint.
[132.240 --> 138.200]  The joint near the end of the finger is called the distal IP joint or DIP joint.
[138.200 --> 143.360]  The thumb only has one IP joint between the two thumb phalanges.
[143.360 --> 148.480]  The IP joints of the digits also work like hinges when you bend and straighten your fingers
[148.480 --> 150.760]  and thumb.
[150.760 --> 157.120]  The joints of the hand, fingers and thumb are covered on the ends with Articular Cardlich.
[157.120 --> 160.720]  This white shiny material has a rubbery consistency.
[160.720 --> 165.920]  The function of Articular Cardlich is to absorb shock and provide an extremely smooth surface
[165.920 --> 168.320]  to facilitate motion.
[168.320 --> 173.120]  There is Articular Cardlich essentially everywhere that two bony surfaces move against
[173.120 --> 176.840]  one another or articulate.
[176.840 --> 181.000]  Ligaments are tough bands of tissue that connect bones together.
[181.000 --> 185.360]  Two important structures called collateral ligaments are found on either side of each
[185.360 --> 187.640]  finger and thumb joint.
[187.640 --> 192.200]  The function of the collateral ligaments is to prevent abnormal sideways bending of each
[192.200 --> 192.600]  joint.
[196.920 --> 203.720]  In the PIP joint, the middle joint between the main knuckle and the DIP joint, the strongest
[203.720 --> 206.360]  ligament is the boulder plate.
[206.360 --> 211.000]  This ligament connects the proximal phalanx to the middle phalanx on the palm or side
[211.000 --> 212.680]  of the joint.
[212.680 --> 217.480]  The ligament tightens as the joint is straightened and keeps the PIP joint from bending back too
[217.480 --> 220.440]  far or hyper extending.
[220.440 --> 227.840]  Here deformities can occur when the boulder plate loosens from disease or injury.
[227.840 --> 232.040]  Many of the muscles that control the hand start at the elbow or forearm.
[232.040 --> 236.240]  They run down the forearm across the wrist and hand.
[236.240 --> 240.200]  Some control only the bending or straightening of the wrist.
[240.200 --> 243.480]  Others influence motion of the fingers or thumb.
[243.480 --> 247.980]  Many of these muscles help position and hold the wrist and hand while the thumb and
[248.060 --> 252.300]  fingers grip or perform fine motor actions.
[252.300 --> 257.980]  Most of the small muscles that work the thumb and little finger start on the carpal bones.
[257.980 --> 263.300]  The bulge of muscle at the base of the thumb in the palm is called the Thinar iminence.
[263.300 --> 269.380]  The bulge of muscle at the base of the little finger is called the hypo-thinar iminence.
[269.380 --> 272.180]  Four muscles make up the Thinar iminence.
[272.180 --> 275.100]  The abductor polisus brevis.
[275.100 --> 277.540]  Flexor polisus brevis.
[277.540 --> 282.220]  The abductor polisus and opponent's polisus.
[282.220 --> 285.140]  Polisus is the Latin term for thumb.
[285.140 --> 289.580]  Each of these muscles begins at the wrist and each has a tendon that attaches to a different
[289.580 --> 294.340]  location on the base of the proximal phalanx of the thumb.
[294.340 --> 301.700]  Their names give a suggestion of what they do when they contract.
[301.700 --> 307.500]  The abductor polisus brevis abducks or moves the thumb away from the midline of the hand.
[307.500 --> 312.980]  The flexor polisus brevis flexes or bends the thumb.
[312.980 --> 319.060]  The abductor polisus adducks or moves the thumb towards the midline of the hand.
[319.060 --> 322.340]  The opponent's polisus moves the thumb into opposition.
[322.340 --> 328.460]  It pulls the thumb out from the palm and turns the pulp of the thumb to face the palm.
[328.460 --> 332.580]  This is the motion that allows you to place the tip of your thumb against the tip of your
[332.580 --> 334.340]  little finger.
[334.380 --> 338.940]  The muscles of the hypotherenar eminence are arranged and function roughly the same in the
[338.940 --> 341.060]  little finger.
[341.060 --> 346.620]  The smallest muscles that originate in the wrist and hand are called the intrinsic muscles.
[346.620 --> 351.980]  The intrinsic muscles guide the fine motions of the fingers by getting the fingers positioned
[351.980 --> 358.060]  and holding them steady during hand activities.
[358.060 --> 363.340]  The tendons that allow each finger joint to straighten are called the extensor tendons.
[363.340 --> 367.660]  The extensor tendons of the fingers begin as muscles that arise from the backside of
[367.660 --> 369.620]  the forearm bones.
[369.620 --> 374.260]  These muscles travel towards the hand where they eventually connect to the extensor tendons
[374.260 --> 377.540]  before crossing over the back of the wrist joint.
[377.540 --> 382.780]  As they travel into the fingers, the extensor tendons become the extensor hood.
[382.780 --> 387.460]  The extensor hood flattens out to cover the top of the finger and sends out branches
[387.460 --> 393.140]  on each side that connect to the bones in the middle and end of the finger.
[393.140 --> 397.520]  The place where the extensor tendons attaches to the middle phalanx is called the central
[397.520 --> 399.120]  slip.
[399.120 --> 403.820]  When the extensor muscles contract, they tug on the extensor tendons and straighten
[403.820 --> 405.620]  the finger.
[405.620 --> 411.300]  Problems occur when the central slip is damaged as can happen with a tear.
[411.300 --> 416.020]  The flexor tendons allow the fingers and thumb to flex or bend to grip objects in the
[416.020 --> 417.900]  palm of the hand.
[417.900 --> 422.740]  The strong flexor muscles begin in the forearm, and just before they enter the wrist, the
[422.740 --> 426.460]  flexor muscles form the flexor tendons.
[426.460 --> 431.100]  The flexor tendons travel through the carpal tunnel, through the palm, and two tendons
[431.100 --> 435.660]  each travel into the bowler side of each finger.
[435.660 --> 441.160]  These two tendons, the flexor superficialis and flexor perfundis, travel through a special
[441.160 --> 446.180]  tunnel formed by a series of specialized ligaments that form police.
[446.180 --> 450.420]  The flexor superficialis connects to the base of the middle phalanx.
[450.420 --> 455.660]  The flexor perfundis tendon connects to the base of the distal phalanx.
[455.660 --> 459.780]  The thumb is a bit different since it only has two phalanxes.
[459.780 --> 464.340]  The flexor polisus longest begins in the forearm, and its tendon connects to the base
[464.340 --> 467.300]  of the distal phalanx of the thumb.
[467.300 --> 472.220]  The flexor polisus bravest muscle begins in the wrist, and its tendon connects to the
[472.220 --> 479.300]  base of the proximal phalanx of the thumb.
[479.300 --> 484.420]  All of the nerves that travel to the hand and fingers begin together at the shoulder.
[484.420 --> 495.300]  The radial nerve, the median nerve, and the ulnar nerve.
[495.300 --> 500.380]  These nerves carry signals from the brain to the muscles that move the arm, hand, fingers,
[500.380 --> 501.980]  and thumb.
[501.980 --> 507.820]  The nerves also carry signals back to the brain about sensations such as touch, pain,
[507.820 --> 510.500]  and temperature.
[510.500 --> 514.340]  The radial nerve runs along the thumb side edge of the forearm.
[514.340 --> 518.940]  It wraps around the end of the radius bone toward the back of the hand.
[518.940 --> 523.660]  It gives sensation to the back of the hand from the thumb to the third finger.
[523.660 --> 528.100]  It also supplies the back of the thumb, and just beyond the main knuckle of the back
[528.100 --> 531.780]  surface of the ring and middle fingers.
[531.780 --> 536.180]  The median nerve travels through a tunnel within the wrist called the carpal tunnel.
[536.180 --> 541.580]  This nerve gives sensation to the thumb, index finger, long finger, and half of the ring
[541.580 --> 542.580]  finger.
[542.580 --> 546.980]  It also sends a nerve branch to control the thinar muscles of the thumb.
[546.980 --> 551.220]  The thinar muscles help move the thumb, and let you touch the pad of your thumb to the
[551.220 --> 556.740]  tips of each finger on the same hand, a motion called opposition.
[556.740 --> 561.740]  The ulnar nerve travels through a separate tunnel called Gion's canal.
[561.740 --> 566.700]  This tunnel is formed by two carpal bones, the pisa form and hamate, and the ligament
[566.700 --> 568.460]  that connects them.
[568.460 --> 572.660]  After passing through the canal, the ulnar nerve branches out to supply feeling to the little
[572.660 --> 576.380]  finger and half the ring finger.
[576.380 --> 581.140]  Branches of this nerve also supply the small muscles in the palm and the muscle that pulls
[581.140 --> 583.820]  the thumb toward the palm.
[583.820 --> 589.020]  Each finger has a pair of sensory nerves, one on each side, that runs to the tip of the
[589.020 --> 590.020]  finger.
[590.100 --> 597.180]  These nerves are called the digital nerves and supply sensation to the fingers.
[597.180 --> 601.860]  Traveling along with the nerves are the large vessels that supply the hand with blood.
[601.860 --> 606.540]  The largest artery is the radiolartery that travels across the front of the wrist closest
[606.540 --> 608.060]  to the thumb.
[608.060 --> 612.100]  The radiolartery is where the pulse is taken in the wrist.
[612.100 --> 617.020]  The ulnar artery runs next to the ulnar nerve through Gion's canal, which has been mentioned
[617.020 --> 618.500]  earlier.
[618.500 --> 623.380]  The ulnar and radiolarteries arch together within the palm of the hand, supplying the
[623.380 --> 626.580]  front of the hand, fingers, and thumb.
[626.580 --> 631.300]  Other arteries travel across the back of the wrist to supply the back of the hand, fingers,
[631.300 --> 634.540]  and thumb.
[634.540 --> 639.020]  When our hands are free of problems, it's easy to take the complex anatomy of the hand
[639.020 --> 640.820]  for granted.
[640.820 --> 642.860]  The hand is formed by numerous structures.
[642.860 --> 646.820]  Each has an important role in the normal hand function.
[646.820 --> 651.500]  These conditions that change the way these structures work can greatly impact whether
[651.500 --> 653.020]  the hand functions normally.