Episode Transcript
[00:00:00] Speaker A: Have you ever felt, like, a surprising hitch in your step or maybe a nagging ache that pops up in your neck and just wondered, how is my body actually doing this? What's really going on under the skin? Because it's way beyond just flexing or extending, isn't it? Our bodies are this symphony of incredibly complex movements. So today we're taking a real deep dive into the musculoskeletal system, bones and muscles.
Our mission really is to unpack that intricate dance between stabilization and mobilization.
We want to reveal the surprising connections, you know, and the essential roles of all the forces moving your body basically from head to toe. Think of it as a shortcut to truly understanding your own physical landscape.
[00:00:42] Speaker B: It's true the sheer amount of anatomical information can feel, well, overwhelming. But the good news is the core principles, how our bodies actually move, they're fundamental. They don't really change.
We're going to try and distill this down into clear, impactful insights so you'll get this foundational understanding that honestly underpins almost every physical activity you can think of.
[00:01:00] Speaker A: Yeah, and get ready for those aha moments, because I think by the end of this, you'll really start piecing together how parts of your body you thought were totally separate. Maybe your deep core and, like the muscles moving your big toe are actually all part of one incredible interconnected system.
[00:01:19] Speaker B: Okay, so let's unpack this. Before we dive into specific muscles, maybe we should establish some common ground, some basic language.
[00:01:26] Speaker A: Good idea. A shared vocabulary is key.
[00:01:28] Speaker B: Right. So when we talk about connections, ligaments, those are the sturdy bands connecting bone directly to bone.
[00:01:35] Speaker A: Yeah, exactly. Bone to bone. And then tendons are those tough fibrous cords attaching muscle to bone, muscle to bone.
[00:01:42] Speaker B: Okay. And that difference is actually super practical, isn't it? Like, a sprain is ligaments.
[00:01:47] Speaker A: Right. Damage to ligament. While a strain is usually the muscle or the tendon involved. Knowing that difference just helps you understand what's actually going on when something hurts.
[00:01:55] Speaker B: Totally. Then there's fascia, which is. Wow. This often overlooked fibrous connective tissue that basically packages everything. Muscles, nerves, blood vessels. It weaves it all together through your entire body. It's like the structural webbing, isn't it? Kind of holds the whole system together.
[00:02:09] Speaker A: Yeah, like internal cling film.
A joint, obviously, is just where two or more bones meet, allowing movement.
[00:02:17] Speaker B: Simple enough.
[00:02:18] Speaker A: And when we describe any movement, we always start from anatomical neutral, that standard upright standing position, palms forward. It's our universal baseline. Right.
[00:02:29] Speaker B: It is our starting point for everything.
And muscles well, they rarely work alone. The origin is typically the attachment point that stays more stationary, usually closer to the center of the body. The proximal part.
[00:02:42] Speaker A: Okay, proximal.
[00:02:43] Speaker B: While the insertion is the distal attachment, the part that usually moves. Think about your bicep origin up at the shoulder. Insertion down on the forearm.
[00:02:51] Speaker A: Right. So when you flex, the forearm moves towards the shoulder. Makes sense.
[00:02:54] Speaker B: Exactly. And in that movement, muscles take on different roles. The agonist, or the prime mover, is the main muscle doing the work. Your deltoid, for example, when you lift your arm out sideways.
[00:03:05] Speaker A: The main guy.
[00:03:06] Speaker B: Yeah. Then the antagonist works in opposition.
It controls or slows down that movement, like a tight latissimus dorsi. That big back muscle can actually stop your arm from going higher overhead. It opposes the deltoid's action.
[00:03:20] Speaker A: Ah, okay. So they work in pairs, agonist and antagonist. What about synergists?
[00:03:25] Speaker B: Synergists are helpers. They assist the agonist. And then you have stabilizers, which are absolutely crucial. These muscles lock down a joint, preventing unwanted movement, providing a solid base.
[00:03:36] Speaker A: Like your gluteus media is holding your hip steady when you walk.
[00:03:38] Speaker B: Perfect example. Stops your pelvis tilting side to side. And then the mobilizers are simply the muscles generating the actual movement. So, yeah, it's this constant ballet between stabilizing and mobilizing.
[00:03:49] Speaker A: It's also fascinating how the muscles shape its form, really dictates its function. You mentioned convergent muscles, right?
[00:03:56] Speaker B: Like your pec major or gluteus maximus. Wide origin, narrowing to an insertion. They're built for generating maximum force, max.
[00:04:03] Speaker A: Force, and parallel muscles.
[00:04:05] Speaker B: Think hamstrings. Fibers run side by side. These are designed for longer, larger ranges of motion. And then you have pennate muscles, like in your quads or deltoids. Their fibers are arranged like a feather, super strong, packed with fibers for immense power.
And here's something really interesting. A common misconception, actually. When muscles get bigger from exercise, that's hypertrophy.
[00:04:27] Speaker A: Hypertrophy. Okay.
[00:04:28] Speaker B: Crucially, this isn't getting more muscle fibers. That's hyperplasia. And it's, well, pretty rare in humans. Afterward, developed hypertrophy is an increase in the size of your existing individual muscle fibers.
[00:04:39] Speaker A: So the cells themselves get bigger.
[00:04:41] Speaker B: Exactly. Your body responds to the challenge by making those specific cells larger and stronger, not by adding new ones.
[00:04:48] Speaker A: Fascinating. Okay, let's shift gears. How about we move up to the neck, the most mobile part of the spine?
[00:04:53] Speaker B: Absolutely. The cervical spine's range of motion is incredible. Flexion, like 80, 90 degrees forward extension. 70 back rotation, a full 90 degrees.
[00:05:02] Speaker A: Side to side, which is amazing. But that hypermobility also means that the balance between strength and flexibility in all those neck muscles is just paramount.
[00:05:11] Speaker B: It really is. It's a delicate balance up there.
[00:05:13] Speaker A: And speaking of neck issues, here's a pet peeve alert. You know when you're doing crunches or some ab exercise and you feel that strain in your neck and someone just says, use your abs more.
[00:05:24] Speaker B: Oh, yeah, I hear that one a lot.
[00:05:26] Speaker A: Well, here's the thing.
No abdominal muscle directly connects to your neck bones or your skull. None.
So the fix isn't just squeeze your abs harder. It's about strengthening your core. Yes, but so your abs can actually lift your shoulders and head without your neck muscles jumping in to desperately compensate.
[00:05:46] Speaker B: That's a perfect example of compensation, isn't it? The body just finds a way, even if it's not efficient or comfortable. And talking neck muscles, we generally have deep stabilizers and more superficial mobilizers.
[00:05:57] Speaker A: Okay, deep versus superficial.
[00:05:59] Speaker B: Yeah. Think of the suboccipital muscles. Tiny little guys deep under the base of your skull. They're primarily stabilizers, but they're also packed with proprioceptors.
[00:06:07] Speaker A: Proprioceptors? Sensory input.
[00:06:09] Speaker B: Exactly. They give your brain constant feedback about where your head is in space. They're tightly linked to your eye movements, too, Coordinating that writing reflex that keeps your head level and balanced. So super important for coordination.
[00:06:22] Speaker A: Wow. Tiny muscles, big job. So while those deep ones are stabilizing and sensing, the superficial ones are doing the bigger movement.
[00:06:31] Speaker B: Precisely. Take the sternocleidomastoid, the scm.
Big muscle on the side of your neck. It's a multitasker. Flexes your neck forward, extends your head back, bends your head sideways, and rotates your head to the opposite side.
[00:06:44] Speaker A: Opposite side rotation. Okay. Complex.
No wonder it's involved in things like whiplash.
[00:06:49] Speaker B: Definitely. Its complexity makes it vulnerable. Now, building on that idea of stability, let's talk about the core. People usually think abs, but it's much more than that. It's really like a dynamic canister.
[00:06:59] Speaker A: A canister. Okay, explain that.
[00:07:01] Speaker B: Well, think of the diaphragm as the top lid. When you inhale, it contracts downwards powerfully, increasing pressure inside your abdomen from above.
[00:07:08] Speaker A: Right. Like pushing down.
[00:07:09] Speaker B: Then the pelvic floor muscles form the bottom. They act like a strong, supportive hammock, creating upward pressure, supporting your organs and really boosting overall core strength. From below.
[00:07:20] Speaker A: Top and bottom sealed. What about the sides?
[00:07:22] Speaker B: Good question.
Wrapping around the front like a natural corset, is your Transversus abdominis. This muscle compresses everything inward, creating anterior pressure. But importantly, it's a stabilizer, not immobilizer. Its job is to brace and draw in, not flex or twist you.
[00:07:39] Speaker A: So it cinches you in.
[00:07:41] Speaker B: And the back of the canister, that's largely the multifidus. Deep muscles running along the spine, creating pressure from the back. Think of them like a sheath of a sword encasing your spine segment by segment, usually spanning 2, 4 vertebrae, essential for local deep spinal stability.
[00:07:55] Speaker A: Wow. Okay. Diaphragm top, pelvic floor, bottom. Transverse is front. Multifit is back. That's a solid image.
[00:08:01] Speaker B: And we absolutely cannot forget the thoracolumbar fascia, this huge, wide sheet of highly innervated connective tissue in your lower back.
So many crucial muscles attach into it. Lats, erector, spinae, quadratus, lumborum, multifidus. Even the deepest abdominals, highly innervated.
[00:08:16] Speaker A: So it sends a lot of signals.
[00:08:17] Speaker B: Tons of sensory information, and it's incredible. Early anatomists used to sometimes just cut it away, thinking it was just packing material.
They didn't realize its profound role in structure, support, and transmitting forces across the entire trunk. It's a central hub.
[00:08:33] Speaker A: Mind blowing. Okay, so if those muscles create the stable canister, which. Which ones actually move the spine? Let's talk mobilizers. Abdominals first.
[00:08:41] Speaker B: Sure. Working from deep to superficial. After that, transverses. You hit your obliques, internal and external. These are your torso's twisting and side bending engines.
[00:08:51] Speaker A: Right. How do they work?
[00:08:52] Speaker B: The internal obliques, Their fibers run diagonally upwards. If one side contracts, it laterally flexes and rotates your spine to the same side. If both contract, they help flex your spine forward.
[00:09:03] Speaker A: Okay, Internals, same side rotation.
[00:09:06] Speaker B: Then the external obliques. Their fibers run diagonally downwards, like putting your hands in your pockets. One side contracting laterally. Flexes to the same side, but rotates your spine to the opposite side.
[00:09:16] Speaker A: Ah, opposite side rotation for the externals, that's key for powerful twists. Right. Like throwing a ball.
[00:09:21] Speaker B: Exactly. That opposing action is crucial. And then, most superficially, you have the rectus abdominis, the six pack muscle. Its fibers run vertically, and its main job is flexing the spine, like in a crunch.
[00:09:35] Speaker A: Got it. What about the back muscles that move the spine?
[00:09:38] Speaker B: The main mobilizers there are the powerful erector spinae group. These long muscles run all along your spine. They're your primary extensors, pulling you upright against gravity. But they also help with side bending and a bit of rotation.
[00:09:52] Speaker A: Erectors keep you erect. Makes sense. Any others?
[00:09:56] Speaker B: Definitely the quadratus lumborum or ql. It's in your low back, kind of between your ribs and pelvis. It extends and laterally flexes the spine, but it's also known as the hip hiker. If your ribs are stable, it can actually lift your pelvis up on one side.
[00:10:09] Speaker A: Hip hiker. Interesting.
[00:10:10] Speaker B: And then we absolutely have to talk about the iliopsoas. This is a real bridge connecting your trunk to your legs, made of the psoas major and the iliacus.
[00:10:18] Speaker A: Okay. Iliopsoas. I hear a lot about the psoas.
[00:10:20] Speaker B: You do? Especially the psoas major. It originates way up high from T12 down to L5 on your spine, then crosses the hip to attach to your femur. It's a powerful hip flexor. Yes. But because of that spinal attachment, it can also pull your lumbar spine forward into extension, or lordosis. This is a massive contributor to low back pain, especially for people who sit a lot.
[00:10:44] Speaker A: Because it gets tight from sitting.
[00:10:46] Speaker B: Exactly. Chronically shortened. And what's truly fascinating, the lumbar plexus, this bundle of major nerves heading down your leg actually passes through the fibers of the psoas to the muscle.
[00:10:58] Speaker A: Seriously?
[00:10:59] Speaker B: Which raises a really important point. If your psoas is chronically tight, think about the potential impact not just on your posture and hip movement, but maybe even on nerve function down into your leg.
[00:11:09] Speaker A: Wow, that really drives home how interconnected everything is.
A tight muscle isn't just tight. It can affect nerves, posture, everything. Okay, let's shift focus again. How about the arms and shoulders? A marvel of mobility and power, right?
[00:11:23] Speaker B: Absolutely. The shoulder joint, the glenohumeral joint, has this incredible range of motion, mainly because the socket is quite shallow compared to the ball.
[00:11:31] Speaker A: More like a golf ball on a tee than a deep socket, pretty much.
[00:11:34] Speaker B: Which allows for amazing freedom. But it means we rely heavily on the surrounding muscles, layered precisely for control, stability, and generating power.
[00:11:44] Speaker A: So stability has to come first.
[00:11:45] Speaker B: You got it. And for that, we look to the deep stabilizers, the famous rotator cuff. Remember the mnemonic? Sits.
[00:11:52] Speaker A: Sits. Supraspinatus, infraspinatus, teres minor, and subscapularis.
[00:11:56] Speaker B: Perfect.
Now, they each have individual actions. Supraspinatus, for instance, is key for initiating abduction, lifting your arm out to the side, especially those first 30 degrees or so. Infraspinatus and tyrus minor are lateral rotators. Subscapularis is a medial rotator.
[00:12:11] Speaker A: Okay. They do move the arm.
[00:12:13] Speaker B: They do. But Their primary collective role is deep stabilization. They work together constantly to keep the head of the humerus, the ball, snugly centered in that shallow glenoid socket. During all those big arm movements, there are the fine tuners and stabilizers.
[00:12:27] Speaker A: Got it. Deep stability first.
So beyond the cuffs, stabilizing the joint itself, what about the muscles controlling the platform? It sits on the scapula, the shoulder blade. That has to be stable too, right?
[00:12:38] Speaker B: Critically important, the scapula needs to move correctly to allow full arm motion.
Think about your serratus anterior. It's deep under your lats, and it basically holds the scapula flat against your ribs, preventing that winging look, vital for reaching overhead smoothly.
[00:12:54] Speaker A: Okay, serratus holds it down. What else moves the scapula?
[00:12:57] Speaker B: Well, there's the pectoralis minor. It sits underneath your main pec major muscle. It helps pull the scapula forward and down. But here's a really crucial anatomical detail.
[00:13:06] Speaker A: Oh, another connection.
[00:13:07] Speaker B: Yep. The brachial plexus, the big bundle of nerves for your arm, the subclavian artery and the vein all run directly underneath the pectoralis minor muscle.
[00:13:16] Speaker A: Under the muscle. Wow.
[00:13:18] Speaker B: So if that pec minor gets super tight, maybe from posture or overuse, it can potentially compress those vital nerves and blood vessels. It's a direct link, showing how muscle tension can cause issues like tingling or numbness down the arm.
[00:13:31] Speaker A: That's incredible. Okay, pec minor serratus.
What about pulling the shoulder blades back?
[00:13:37] Speaker B: That's primarily your rhomboids, major and minor, and the middle fibers of your trapezius, they retract the scapulae, squeezing them together. And the levator scapula, which we mentioned with the neck, elevates the scapula, but also helps rotate it downward. And the trap, well, it's huge. Upper fibers elevate and retract, middle fibers retract, lower fibers retract and depress. It does a bit of everything for the scapula, plus moving the head and neck.
[00:14:01] Speaker A: Okay, so we've stabilized the joint with the cuff, stabilize the platform with the scapular muscles.
Now for the big movers, the power muscles of the shoulder.
[00:14:09] Speaker B: Now we get to the prime movers. The deltoid, that cap of muscle over your shoulder. It has three distinct anterior, middle, posterior. They work together or individually to flex, abduct, extend, and rotate your arm in pretty much any direction.
[00:14:24] Speaker A: The all rounder, definitely.
[00:14:25] Speaker B: Then you have the latissimus dorsi, that huge wing like muscle on your back. It's a powerhouse for extending, adducting, pulling, the arm down and in and medially rotating the shoulder.
Fun fact. Its fibers actually twist before they insert on the humerus, giving it extra leverage for powerful pulling motions.
[00:14:43] Speaker A: A twist for power. Cool. What works with the lat, often called.
[00:14:48] Speaker B: The lat's little helper, is the teres major. It performs very similar actionsextension, adduction, medial rotation, but it's not part of the rotator cuff. That's a key distinction.
[00:14:57] Speaker A: Got it. Teres major helps the lat. Teres minor is cuff and the chest. The pectoralis major, that large, powerful chest muscle, primarily adducts and medially rotates the shoulder, but its upper fibers help with flexion. Lifting forward and lower fibers can help with extension from a flexed position. A real powerhouse. And don't forget, even the biceps and triceps cross the shoulder joint, so they assist in shoulder flexion and extension, respectively, on top of their elbow action.
[00:15:24] Speaker B: Right.
[00:15:24] Speaker A: Multi joint muscles. Okay, this is great. Let's ground ourselves. Now move down to the lower body. The engine room. Right. Power stability, shock absorption.
[00:15:32] Speaker B: Exactly. First, quick terminology check. Anatomically, the hip refers to the joint itself. The thigh is the region of the femur between hip and knee. And the leg is technically the part below the knee, tibia and fibula region.
[00:15:47] Speaker A: Hip, thigh, leg. Got it. So this whole lower extremity is about massive power, but also stability and handling those forces coming up from the ground.
[00:15:55] Speaker B: Every step you take immense forces. And unlike the shoulder, shallow socket, the hip socket, the acetabulum is much deeper. That gives it inherently more bony stability, which is good because the forces are huge down there.
[00:16:08] Speaker A: Makes sense. Where do we start? Deep muscles first, skin.
[00:16:11] Speaker B: Let's do that. The deep lateral rotators of the hip. There are several small ones, but let's focus on the piriformis. It's the largest of this group.
[00:16:18] Speaker A: Piriformis. I've heard of piriformis syndrome.
[00:16:20] Speaker B: Exactly. And here's why it's clinically relevant. Normally, it laterally rotates your hip when your leg is straight or slightly extended. But. And this is the kicker, when your hip is flexed past 90 degrees, like when sitting or squatting deep, its line of pull actually changes, and it becomes an internal rotator of the hip.
[00:16:37] Speaker A: Wait, what? It switches jobs depending on the angle.
[00:16:40] Speaker B: Precisely. It also helps stabilize the femoral head in the socket.
But the big thing is the sciatic nerve. The largest nerve in your body, typically runs right underneath the piriformis muscle as it exits the pelvis.
[00:16:53] Speaker A: Ah, so the piriformis gets tight or.
[00:16:54] Speaker B: Spasmed it can compress or irritate the sciatic nerve, causing pain down the leg that mimics true sciatica. Hence piriformis syndrome. Understanding its anatomy and action is key. There.
[00:17:05] Speaker A: That is a classic aha moment. Okay, deep rotators done. What about the major hip movers? Flexors first?
[00:17:11] Speaker B: Sure. We already met the primary hip flexor, the iliopsoas, psoas, major and iliacus, linking the spine and pelvis to the femur. Powerful flexor also helps a bit with lateral rotation.
[00:17:22] Speaker A: Right. The potential back pain culprit.
[00:17:24] Speaker B: Then you have the adductor group on your inner thigh. Pectineus, adductor brevis, longus magnus. Their main job is adduction, pulling your leg towards the midline. They also assist in medial rotation.
[00:17:38] Speaker A: Groin muscles often gets strained, right?
[00:17:41] Speaker B: Very common, especially the pectineus. But the adductor magnus, the biggest and deepest one, is particularly interesting. It's so large, its posterior fibers actually help extend the hip. Some people even call it the fourth hamstring because of that extension roll.
[00:17:55] Speaker A: Fourth hamstring, okay. Versatile muscle. Now, hip extension and abduction. Gotta be the glutes, right?
[00:18:00] Speaker B: Absolutely. The star is the gluteus maximus. Largest muscle in the body. Most powerful hip extensor. Also abducts and laterally rotates the hip. Crucial for getting up from a chair, climbing stairs, running, jumping. It also ties into that thoracolumbar fascia we talked about.
[00:18:16] Speaker A: The powerhouse. What's underneath it?
[00:18:17] Speaker B: Directly underneath lies the gluteus medius. And this one is absolutely critical for pelvic stability. When you're on one leg, like during walking or running, it prevents the opposite side of your pelvis from dropping down.
[00:18:28] Speaker A: So if glute medius is weak, you get that hip drop. Kind of wobbly gait.
[00:18:32] Speaker B: Exactly. Leads to all sorts of compensation patterns and potential pain down the chain. Knee, ankle, even back. And deepest is the gluteus minim, which also helps abduct and medially rotate the hip glute.
[00:18:44] Speaker A: Max med min power, stability and assisting. Got it.
Now, what about those two joint muscles crossing the hip?
[00:18:53] Speaker B: Ah, yes, they make things interesting. For two joint hip flexors, the main one is the rectus femoris. It's the only one of your four quadriceps muscles that crosses the hip joint, rectus femoris.
[00:19:03] Speaker A: So it flexes the hip and extends the knee.
[00:19:05] Speaker B: Correct. Dual action, vital for things like kicking a ball or sprinting. You also have the tensor fascia latae tfl up on the side of your hip it flexes medially, rotates and abducts the hip. And it inserts into that famous, often tight iliotibial IT band.
[00:19:21] Speaker A: TFL and the it band often talked.
[00:19:23] Speaker B: About together very often. Then there's the sartorius. The longest muscle in the body runs diagonally across the thigh, called the tailor's muscle because it helps you cross your legs. Flexes laterally, rotates and abducts the hip. Plus it flexes the knee longest muscle.
[00:19:36] Speaker A: Wow. Any others?
[00:19:37] Speaker B: The gracilis part of the adductor group, also crosses the knee and assists in knee flexion.
[00:19:42] Speaker A: Okay, now for the two joint hip extensors, the hamstrings.
[00:19:45] Speaker B: The hamstrings. Three main ones. Semitendinosus, semimembranosus. These are the medial ones and biceps femoris, the lateral one. All of them extend the hip and flex the knee. They also contribute to posterior pelvic tilt, like when you tuck your tailbone under medial hams.
[00:20:00] Speaker A: Lateral hamster.
Any key differences?
[00:20:03] Speaker B: The medial ones weakly assist medial hip rotation. The semitendinosus is one of three muscles, along with sartorius and gracilis, that insert together at a spot on the tibia called the pes inserinus or goose's foot. Important spot for knee stability.
[00:20:17] Speaker A: PEs and serenis. Okay.
[00:20:19] Speaker B: And the biceps femoris, the lateral one is the only hamstring to attach to the fibula head on the outside of the knee. It also laterally rotates the hip and has a direct fibrous connection to the sacrotuberous ligament in the pelvis and linking leg action to pelvic stability.
[00:20:34] Speaker A: Fascinating connections everywhere. Okay, let's move right down to the knee and ankle. Now, knee extensors. That's the quadriceps group, right?
[00:20:41] Speaker B: Yep. The quads. We mentioned rectus femoris crossing the hip. The other three are the vasti muscles. Vastus lateralis outside, vastus medialis inside, and vastus intermedius deepest under rectus femoris. All four converge into the patellar tendon ligament to insert on the tibial tuberosity, that bump below your kneecap. And their main job, extending the knee.
[00:21:05] Speaker A: And there's always talk about the vmo, right? Vastus medialis obliquus, that inner part.
[00:21:10] Speaker B: There is lots of debate about whether you can specifically isolate and strengthen just that oblique part for knee tracking, but the general consensus now is that you need strong, balanced function of all the vasti. And achieving full knee extension in exercises is key for strengthening the entire medialis portion effectively.
[00:21:26] Speaker A: So focus on Balance strength and full extension.
[00:21:29] Speaker B: Got it. Knee flexors. Then we know the hamstrings.
[00:21:31] Speaker A: Hamstrings are the main ones, but also the gastrocnemius, that big calf muscle. Because it crosses the knee joint, it assists in knee flexion, especially when the foot is free.
[00:21:39] Speaker B: The calf helps bend the knee. Interesting. Yep. And there's a small, deep muscle called the popliteus right behind the knee. Its main job is to unlock the knee from full extension, initiating flexion. It's like the key turning the lock. And the tiny plantaris, sometimes called the freshman's nerve, because it looks like one is a very weak knee flexor and ankle plantar flexor. And some. Some people don't even have it.
[00:22:01] Speaker A: Okay. Poplius unlocks, gastrocnemius, assists. Now ankle movements.
[00:22:06] Speaker B: Pointing toes is plantar flexion, like pressing a gas pedal. Lifting toes up is dorsiflexion.
[00:22:11] Speaker A: Okay. And turning the sole of the foot.
[00:22:13] Speaker B: Inwards, that's inversion or supination. Turning the sole outwards is easion or pronation.
[00:22:19] Speaker A: Inversion, supination, evension, pronation. Got it. So who does the pushing off the plantar flexion?
[00:22:24] Speaker B: Primarily, your two big calf muscles, the superficial gastrocnemius and the deeper soleus. The soleus is particularly important for stabilizing your ankle when standing. But several deeper muscles running behind the ankle bone also assist plantar flexion and crucially, help support the arch of your foot. These include tibialis posterior flexor digitorum longus. Flexes toes and flexor hallucis longus flexes big toe.
[00:22:47] Speaker A: So arch support comes from muscles, too, not just ligaments.
[00:22:50] Speaker B: Absolutely. And on the outside of the ankle, you have the fibularis or peroneus longus and brevis. They are the primary everters of the foot. Turning the sole outwards. They're often injured in common lateral ankle sprains.
[00:23:02] Speaker A: Everters on the outside.
Makes sense.
[00:23:04] Speaker B: Yeah.
[00:23:05] Speaker A: Endorsiflexion, lifting the foot up.
[00:23:06] Speaker B: The main player there is tibialis anterior running down the shin. Strongest dorsiflexor. And it also inverts the foot. It's the muscle that often gets sore and tired when you walk uphill for a long time, constantly working to lift your foot.
[00:23:19] Speaker A: Clear shin splints. Territory sometimes can be involved.
[00:23:23] Speaker B: Yeah. Assisting it are the extensor digitorum longus and extensor hallucis longus.
And sometimes a small fibularis tertius muscle helps, too. It's amazing how many muscles contribute to seemingly simple actions like inversion or inversion, isn't it? Shows the layers of control.
[00:23:41] Speaker A: It really does.
So, okay, stepping back. What does this all really mean? We've gone on this incredible journey from tiny neck stabilizers to huge leg movers. The thing that just keeps jumping out at me is the sheer profound interconnectedness of it all.
[00:23:58] Speaker B: Absolutely.
[00:23:58] Speaker A: Like we talked about how a tight psoas doesn't just affect the hip. It can pull your spine into extension, maybe causing back pain. Or the piriformis doing that weird rotation switch and potentially bugging the sciatic nerve. And that fascia weaving through everything.
[00:24:11] Speaker B: It really paints a picture, doesn't it? This deep dive shows that understanding your body isn't just about memorizing muscle names from a chart. It's about appreciating this incredible image, intricate ballet of stabilization enabling mobilization, and vice versa.
[00:24:25] Speaker A: Yeah.
[00:24:26] Speaker B: And having this knowledge empowers you. You can start to understand maybe why you feel certain discomforts or how to move more efficiently, or just grasp the true mechanics behind every single physical action makes you a much more informed owner, operator of your own body.
[00:24:41] Speaker A: Definitely. You really do walk away with a, well, a deep dive level of understanding of how these amazing structures work together. It's truly a marvel when you think about it.
[00:24:49] Speaker B: It is. And maybe here's a final thought for you, the learner, to ponder. We talked about muscles enlarging through hypertrophy, right? That cellular increase in size in response to demand.
[00:24:59] Speaker A: Yeah. Bigger cells, not more cells.
[00:25:01] Speaker B: Exactly.
So consider this.
How might a similar understanding of our nervous system's capacity for adaptation and growth, its own kind of hypertrophy or plasticity, change how we approach learning new skills, maybe recovering from injury or even just forming new habits?
What other seemingly invisible systems in your body, like the nervous system or the fascial network, might hold similar profound, interconnected roles, just waiting for us to explore them more deeply?
