<span style="font-weight: 400;">OK OK OK Yes this is a tough one because technically we don't have ‘knee muscles’ do we?? Or do we???</span>

<span style="font-weight: 400;">Well when considering this very point it would probably be prudent to discuss the muscles that cross the knee, right?</span>
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<h1><b>Anterior Knee </b></h1>
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<h2><b>The ‘Quadricep Femoris’ Group</b></h2>
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<span style="font-weight: 400;">‘Quad’ meaning quadruple - </span><i><span style="font-weight: 400;">quattuor</span></i> <span style="font-weight: 400;">or 4 &amp;</span> <i><span style="font-weight: 400;">caput </span></i><span style="font-weight: 400;">meaning ‘head’</span>

<span style="font-weight: 400;">‘Femoris’ meaning relating to the femur or thigh bone. </span>
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<span style="font-weight: 400;">This group is made up of 4 muscles….or maybe 5….or 6…!?!? Read on...</span>
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<h2><b>Rectus Femoris</b><span style="font-weight: 400;"> </span></h2>
&nbsp;

<span style="font-weight: 400;">Meaning ‘</span><i><span style="font-weight: 400;">straight’</span></i><span style="font-weight: 400;"> &amp; femur related.</span>

<span style="font-weight: 400;">The only one in this group to cross 2 joints as opposed to 1. Reaching from the AIIS (anterior inferior iliac spine - feel your most pokey out front hip bone, then this prominence is just below it) to the patella (kneeling bone) ligament/ tibial (shin bone) tuberosity to both flex the hip AND extend the knee…..busy busy busy!!</span>
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<img class="aligncenter wp-image-26107" src="https://biomechanicseducation.com/wp-content/uploads/2021/02/shutterstock_309794156-scaled-1.jpg" alt="" width="273" height="364" />
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<h2><b>Vastus Lateralis (or Vastus Externus)</b></h2>
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<span style="font-weight: 400;">‘</span><i><span style="font-weight: 400;">Vastus</span></i><span style="font-weight: 400;">’ meaning vast or immense &amp; positioned laterally or externally. </span>

<span style="font-weight: 400;">Technically the only muscle of the lateral thigh, its back (posterior) edge lies next to </span><i><span style="font-weight: 400;">bicep femoris</span></i><span style="font-weight: 400;"> (one of the hamstrings - coming up) &amp; it lies deep to that ITB. </span>

<span style="font-weight: 400;">Tracking from linea aspera, gluteal tuberosity, greater trochanter to the tibial tuberosity to extend the knee…...go back to each one of these prominences &amp; press your finger onto each one while visualising the muscle’s placement...go on, try it….</span>
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<img class="aligncenter wp-image-26106" src="https://biomechanicseducation.com/wp-content/uploads/2021/02/shutterstock_1401205709-scaled-1.jpg" alt="" width="346" height="346" />
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<h2><b>Vastus Medialis (or Vastus Internus)</b></h2>
&nbsp;

<span style="font-weight: 400;">The word’s meaning, I am pretty confident you can work out now right!? ‘</span><i><span style="font-weight: 400;">Vastus Medialis’....</span></i><span style="font-weight: 400;">have you read everything up to this point?</span>

<span style="font-weight: 400;">It’s inside the thigh with a kind of tear drop shape this little beauty is also known as VMO or </span><i><span style="font-weight: 400;">vastus medialis oblique</span></i><span style="font-weight: 400;">. </span>

<span style="font-weight: 400;">Often I get asked “</span><i><span style="font-weight: 400;">how do I grow my VMO?”.....</span></i><span style="font-weight: 400;">well it attaches from the medial lip of linea aspera to that tibial tuberosity to also extend the knee….so do that….no its never that simple…..or is it? </span>
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<h2><b>Vastus Intermedius </b></h2>
&nbsp;

<span style="font-weight: 400;">Same as above……you know don’t you!?!?</span>

<span style="font-weight: 400;">Central on the thigh, in the middle &amp; deep to rectus femoris, attaching anterior/lateral shaft of the femur to reach…... GUESS…?????</span>
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<span style="font-weight: 400;">….that tibial tuberosity...yup…. to also extend the knee!</span>
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<img class="aligncenter wp-image-26108" src="https://biomechanicseducation.com/wp-content/uploads/2021/02/shutterstock_309793826-scaled-1.jpg" alt="" width="263" height="350" />

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<span style="font-weight: 400;">What a team eh! </span>
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<span style="font-weight: 400;">But wait! </span>
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<span style="font-weight: 400;">They have some cousins that can appear in some human legs….</span>
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<h2><b>The 5th &amp; 6th Quads!?!</b></h2>
&nbsp;

<span style="font-weight: 400;">Now the reports of a 5th &amp; 6th ‘quad’ seem nonsensical really since the name really indicates just 4 muscles so let’s look at them, what they ACTUALLY do &amp; if they can be described as extra quads…..?</span>
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&nbsp;
<h2><b>Tensa Vastus Intermedius</b></h2>
&nbsp;

<span style="font-weight: 400;">(Tenses, is vast &amp; is in the middle!)</span>

<span style="font-weight: 400;">Please do read these publications to understand Grob’s work better….</span>

<a href="https://pubmed.ncbi.nlm.nih.gov/26732825/" target="_blank" rel="noopener"><span style="font-weight: 400;">(Grob et al 2016) </span></a>

<span style="font-weight: 400;">Staring at the proximal femur at the anterior greater trochanter anterior to (or in front of) vastus intermedius &amp; deep to rectus femoris, it also joins the quadricep tendon, medial patella to medialise the action &amp; ‘tenses’ on the aponeurosis (sheet of pearly white fibrous tissue) of vastus medialis! </span>
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&nbsp;

<img class="aligncenter wp-image-26109" src="https://biomechanicseducation.com/wp-content/uploads/2021/02/TENSA-VASTUS-INTERMEDIUS-1.png" alt="" width="315" height="303" />

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<h2><b>Articularis Genus</b><span style="font-weight: 400;"> </span></h2>
&nbsp;

<i><span style="font-weight: 400;">Articularis</span></i><span style="font-weight: 400;"> means to join with a joint - </span><i><span style="font-weight: 400;">genus</span></i><span style="font-weight: 400;"> means relating a family line or genetic, borrowed from latin for </span><i><span style="font-weight: 400;">birth or origin</span></i><span style="font-weight: 400;">, but relates also to the knee as in this case.</span>

<span style="font-weight: 400;">Originating from the lower (distal) front (anterior) part of the femur to then reach down to the suprapatellar bursa to lift this bursa out of the way during knee extension - how clever!!</span>

&nbsp;

<a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6133144/#:~:text=The%20insertion%20of%20this%20muscle,%2C2%2C8%2D11." target="_blank" rel="noopener"><span style="font-weight: 400;">(Grob et al 2017)</span></a>
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<span style="font-weight: 400;">So technically they are collaborating with the 4 major quads &amp; while they don’t actually extend the knee, they do play a role in the knee extensor’s performance. </span>
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<img class="aligncenter wp-image-26110" src="https://biomechanicseducation.com/wp-content/uploads/2021/02/ARTICULARIS-GENUS-1.jpg" alt="" width="255" height="340" />
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<h1><b>Posterior knee </b></h1>
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<h2><b>The ‘Hamstring’ Group </b></h2>
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<span style="font-weight: 400;">This group is positioned between vastus lateralis (see above) &amp; adductor magnus (see Pelvis HERE)</span>

<i><span style="font-weight: 400;">18th centurion butchers would hang the pig from the tendons at the back of the knee - hence ‘ham-string’ (Andrew Biel, 2010)</span></i>
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<h2><b>Bicep Femoris </b></h2>
&nbsp;

<i><span style="font-weight: 400;">Bicep</span></i><span style="font-weight: 400;"> meaning 2 heads - </span><i><span style="font-weight: 400;">Femoris</span></i><span style="font-weight: 400;"> links it to the femur </span>

<span style="font-weight: 400;">This dude has both long &amp; short heads!  Both attaching to the fibula head &amp; then…..</span>

<span style="font-weight: 400;">The Long head attaches to the medial ischial tuberosity </span>

<span style="font-weight: 400;">While the short head - attaches to the femur.</span>

<span style="font-weight: 400;">This anatomy means it/they will flex the knee, laterally rotate the flexed knee AND assist hip extension! Phew! Its clear why these muscles need some attention in our clients strength programme with all this going on right!?</span>
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<img class="aligncenter wp-image-26111" src="https://biomechanicseducation.com/wp-content/uploads/2021/02/BICEP-FEM-LONG-shutterstock_303082511-scaled-1.jpg" alt="" width="254" height="339" /><img class="aligncenter wp-image-26112" src="https://biomechanicseducation.com/wp-content/uploads/2021/02/BICEP-FEM-SHORT-shutterstock_303082577-scaled-1.jpg" alt="" width="253" height="337" />
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<h2><b>Semimembranosus </b></h2>
&nbsp;

<span style="font-weight: 400;">The most medial hammie, flatter, wider &amp; most ‘</span><i><span style="font-weight: 400;">membranous’</span></i><span style="font-weight: 400;"> looking when you study its anatomy.</span>

<span style="font-weight: 400;">Travelling from that ischial tuberosity to the back (posterior) of the medial nobly bit (condyle) of the tibia (shin bone). </span>

<span style="font-weight: 400;">This also allows it to flex the knee, medially rotate when the knee is flexed AND…...yep…. assist hip extension….pheweeee!</span>
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<img class="aligncenter wp-image-26113" src="https://biomechanicseducation.com/wp-content/uploads/2021/02/SEMIMEM-shutterstock_303066836-scaled-1.jpg" alt="" width="234" height="312" />
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<h2><b>Semitendinosus </b></h2>
&nbsp;

<span style="font-weight: 400;">The thicker but narrower hammie hence named as more ‘</span><i><span style="font-weight: 400;">tendinous</span></i><span style="font-weight: 400;">’...</span>

<span style="font-weight: 400;">Attached from that sit bone (ischial tuberosity) to the upper (proximal) inner (medial) shaft of the tibia (shin bone) to …..yup you guessed it….flex the knee, extend the hip &amp; help lateral rotation when the knee is flexed.</span>
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<img class="aligncenter wp-image-26114" src="https://biomechanicseducation.com/wp-content/uploads/2021/02/SEMITEN-shutterstock_293552699-scaled-1.jpg" alt="" width="234" height="312" />
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<h2><strong>Popliteus</strong></h2>
&nbsp;

<span style="font-weight: 400;">An actual ‘knee’ muscle!</span><span style="font-weight: 400;"> S</span>

<span style="font-weight: 400;">A small muscle ‘popped’ into the back of the knee under gastroc it starts</span><span style="font-weight: 400;"> at the lateral (outer edge) condyle (bony bit) of the femur then</span><span style="font-weight: 400;"> grabs onto the back of the tibia.</span>

<span style="font-weight: 400;">While small, thin, flat, triangular it is a deep muscle &amp; could kinda help the iliotibial band in a way.....have a look &amp; see what you think..!? </span>

<span style="font-weight: 400;">Positioned at the back &amp; lateral it helps medial rotation of the flexed knee</span>

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<span style="font-weight: 400;">BUT</span>

&nbsp;

<span style="font-weight: 400;">Popliteus decides its role in movement depending upon the position of the lower extremity (leg)....although a weak flexor of the knee it’s really important for ‘unlocking’ the knee joint from an extended position. </span><span style="font-weight: 400;">Also occasionally (rarely in fact) an additional muscle called the popliteus minor is seen arising from the femur into the posterior ligament!!</span>

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<span style="font-weight: 400;">Wonder if that would alter anything in terms of movement?</span>
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<img class="aligncenter wp-image-26882" src="https://biomechanicseducation.com/wp-content/uploads/2021/02/shutterstock_440565091_635713970809-scaled-1.jpg" alt="" width="386" height="514" />
<h2><b>Pes Anserinus Tendon</b></h2>
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<span style="font-weight: 400;">This structure requires a mention as you will see...</span>
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<b>Pes (means foot) anserinus</b><span style="font-weight: 400;"> (relating to goose) so this ‘</span><i><span style="font-weight: 400;">goosefoot</span></i><span style="font-weight: 400;">’ is the description of where </span><b>tendons</b><span style="font-weight: 400;"> of three muscles that insert onto the proximal tibia. Namely sartorius, gracilis &amp; semitendinosus.</span>

<span style="font-weight: 400;">They are often described as ‘guy ropes’.</span>
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&nbsp;
<h1><b>Medial Knee</b></h1>
<h2><b>Adductors - see Pelvis </b></h2>
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<h1><b>Lateral knee</b></h1>
<h2><b>Abductors - see Pelvis</b></h2>
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&nbsp;
<h1><b>Knee Joint Actions </b></h1>
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<span style="font-weight: 400;">Flexion </span>

<span style="font-weight: 400;">Extension </span>

<span style="font-weight: 400;">Note: In knee flexion the tibia can rotate medially &amp; laterally </span>

<span style="font-weight: 400;">Also if you read </span><i><span style="font-weight: 400;">Bruunstromm’s</span></i><span style="font-weight: 400;"> knee kinematics (</span><i><span style="font-weight: 400;">Clinical Kinesiology</span></i><span style="font-weight: 400;">) - flexion at the knee involves a slide, roll, hinge combination! </span>
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