Episode Transcript
[00:00:00] Speaker A: Hey there and welcome back to the deep Dive.
[00:00:02] Speaker B: Great to be here.
[00:00:03] Speaker A: Today we're getting into some really fascinating stuff about your upper body.
[00:00:08] Speaker B: Yeah. The mechanics of it all.
[00:00:10] Speaker A: Head, neck, shoulders, arms, the whole system. So whether you're deep into fitness, maybe dealing with some aches and pains, or honestly just curious about how you tick.
[00:00:20] Speaker B: Then this is definitely for you.
[00:00:22] Speaker A: We've been digging into this great resource, the PAI ABC course muscles manual.
[00:00:28] Speaker B: It's packed really detailed.
[00:00:30] Speaker A: Yeah. And it's got some insights that might just change how you think about, you know, moving and staying stable.
[00:00:36] Speaker B: That's the goal today. Right? Go beyond just naming muscles.
[00:00:39] Speaker A: Exactly.
[00:00:40] Speaker B: We want to look at the layers, the deep stabilizers, the big movers on.
[00:00:44] Speaker A: Top, and how they all connect.
[00:00:45] Speaker B: Right. Those connections are often missed, but understanding them helps make sense of why things feel the way they do.
[00:00:52] Speaker A: Okay, let's jump in this manual. It's like a roadmap.
[00:00:56] Speaker B: It is.
[00:00:56] Speaker A: We're going to pull out the key bits, the real aha moments for you.
[00:01:00] Speaker B: Give you that shortcut to understanding these sometimes confusing upper body forces.
[00:01:07] Speaker A: Okay. Starting at the top, head and neck.
[00:01:09] Speaker B: Often overlooked until it hurts.
[00:01:11] Speaker A: Totally. And the manual points out straight away, the cervical spine, your neck. It's the most mobile part of the whole spine.
[00:01:17] Speaker B: Incredible range of motion.
[00:01:18] Speaker A: Yeah. Like 80, 90 degrees. Flexion forward, 70 degrees, extension back, lateral.
[00:01:24] Speaker B: Flexion side to side, maybe 20, 45 degrees.
[00:01:27] Speaker A: And rotation a full 90 degrees each way. Almost like an owl.
[00:01:31] Speaker B: Ah, well, almost.
But that hypermobility means.
Well, it needs really good support.
[00:01:37] Speaker A: Right. The surrounding muscles have to be strong and flexible. It's a balancing act.
[00:01:42] Speaker B: Absolutely. And the manual introduces these muscles from deep to superficial for a reason.
[00:01:47] Speaker A: Ah, okay. Why is that?
[00:01:49] Speaker B: The deeper ones, they're mainly about stability, holding things in place.
[00:01:53] Speaker A: Gotcha.
[00:01:53] Speaker B: The more superficial ones, closer to the surface, they're your big movers. They create the larger actions.
[00:01:58] Speaker A: Okay, that makes sense. And speaking of neck issues, the manual flags this common thing. Maybe you've heard it.
[00:02:04] Speaker B: Let's hear it.
[00:02:04] Speaker A: Someone gets neck pain doing crunches and the advice is just use your abs more.
[00:02:09] Speaker B: Ah, yes, that old chestnut.
[00:02:12] Speaker A: Right. But like, which ab muscle actually connects up to your neck or skull?
[00:02:16] Speaker B: That's the million dollar question, isn't it? And the answer is none of them.
[00:02:21] Speaker A: None really?
[00:02:21] Speaker B: Not directly. Your deep core muscles, they stabilize your spine. Sure, but they aren't built to hold the weight of your head in that position.
[00:02:30] Speaker A: So why does strengthening the core feel like it helps then? Is it just placebo?
[00:02:34] Speaker B: No, no, not placebo. It's Indirect.
Think about it. Strong, deep abs, like your transverse abdominis.
[00:02:42] Speaker A: Okay.
[00:02:42] Speaker B: They create a solid base, a stable platform that lets your upper body and shoulders lift more easily, which means your head can balance better with less strain on those small neck muscles.
[00:02:53] Speaker A: Ah, so it's about better leverage, not direct support.
[00:02:56] Speaker B: Exactly. Better mechanics, Less work for the neck flexors trying to fight gravity all by themselves.
[00:03:01] Speaker A: Okay, so if it's not the abs directly, what are the key neck muscles doing the work? Let's start deep, like you said.
[00:03:07] Speaker B: Okay. Deep ones. You got the deep neck flexors, the longus colli and longus capitis.
[00:03:12] Speaker A: Long longcopitis. Okay.
[00:03:14] Speaker B: They run right along the front of your cervical vertebrae.
Deepest flexors and stabilizers.
[00:03:19] Speaker A: What do they actually do?
[00:03:20] Speaker B: They flex the head and neck forward.
They also help a little with side bending and rotation to the same side, but that's a weaker action for them.
[00:03:28] Speaker A: And the longus colli is even deeper.
[00:03:30] Speaker B: Yeah. Its fibers overlap the longus capitis a bit. These guys are crucial. They're fighting gravity constantly to keep your head up.
[00:03:37] Speaker A: Especially with phones and computers.
[00:03:39] Speaker B: Precisely. They get weak, and then other more superficial muscles jump in and overwork, causing that tight feeling.
[00:03:45] Speaker A: Okay, what else is deep back there?
[00:03:47] Speaker B: Then you have the suboccipitals, tiny muscles right at the base of your skull.
[00:03:51] Speaker A: Suboccipitals. Heard of those? Causing headaches sometimes?
[00:03:54] Speaker B: Very often, yeah. Because the manual says they're less about big movements and more about stability and sensory input.
[00:04:01] Speaker A: Sensory input?
[00:04:02] Speaker B: How so? They are absolutely loaded with proprioceptors.
[00:04:05] Speaker A: Those body awareness sensors.
[00:04:07] Speaker B: Exactly. Your internal gps.
They constantly tell your brain where your head is in space.
Crucial for balance and coordinating movement everywhere else.
[00:04:17] Speaker A: Wow. Tiny muscles doing all that?
[00:04:19] Speaker B: It's incredible. They're like the fine tuning knobs for a head position.
[00:04:22] Speaker A: And they're linked to eye movements, too. And something called the writing reflex.
[00:04:26] Speaker B: Yes, Very closely linked to coordinating eye movements. And the writing reflex. That your body's automatic adjustment to keep your head level and eyes on the horizon.
[00:04:34] Speaker A: Like a cat landing on its feet.
[00:04:36] Speaker B: Kind of. Yeah. It's that subconscious stabilization. So tension here doesn't just feel stiff. It can mess with balance, cause headaches, eye strain, all sorts of things.
[00:04:47] Speaker A: Because they're sending wonky signals.
[00:04:50] Speaker B: Potentially, yes. They're really important little muscles.
[00:04:52] Speaker A: Okay, so those deep stabilizers are vital, but they can get strained by the bigger movers, especially with bad posture. Right. And if you've ever had that nagging knot, like right where your neck meets your shoulder, pulling upwards.
[00:05:05] Speaker B: Oh, yes.
[00:05:06] Speaker A: Chances are, you know Our next muscle, the levator scapula.
[00:05:10] Speaker B: The shoulder blade lifter. A very common troublemaker.
[00:05:13] Speaker A: Tell us about it. Where does it run?
[00:05:14] Speaker B: It starts high up on the side of your neck vertebrae C1 to C4, and runs down to attach to the top inner corner of your scapula, your shoulder blade.
[00:05:23] Speaker A: And the manual mentions something unique about its path.
[00:05:25] Speaker B: Yeah, it actually twists on itself. The fibers that start highest on the neck attach lowest on the scapula and vice versa.
[00:05:32] Speaker A: Huh.
Why the twist?
[00:05:34] Speaker B: That twist allows it to do multiple things.
Working on one side, it lifts the shoulder blade levator.
[00:05:41] Speaker A: Makes sense.
[00:05:42] Speaker B: And it also rotates the scapula downwards. Plus it bends and rotates your head, neck, to the same side.
[00:05:47] Speaker A: So it does a lot. Neck and shoulder.
[00:05:50] Speaker B: Exactly. And if both sides work together, they help extend your neck backwards.
[00:05:55] Speaker A: So it's a bridge muscle.
[00:05:56] Speaker B: Absolutely. And that dual roll makes it super prone to tension, especially if your deep neck muscles are weak. Or if you habitually shrug your shoulders under stress.
[00:06:04] Speaker A: Haha. Stress, shrug. I know that one.
[00:06:06] Speaker B: We all do.
And trying to fix levator scapula pain by only looking at the neck or only the shoulder often misses the point because it connects both.
[00:06:15] Speaker A: Okay. This interconnectedness is becoming really clear moving down into the shoulder now, which is.
[00:06:20] Speaker B: Crucial because so many shoulder muscles influence the neck. They cross over, attach to the skull or neck bones.
[00:06:26] Speaker A: You really can't separate them.
[00:06:28] Speaker B: Not effectively, no. And the shoulder joint itself, the glenohumeral.
[00:06:31] Speaker A: Joint, the ball and socket.
[00:06:33] Speaker B: Right. It's built for amazing mobility. Super shallow socket, which means it lacks inherent bony stability. It really relies on muscles, tendons, ligaments to hold it together.
[00:06:43] Speaker A: Okay, so let's talk muscles. The famous rotator cuff.
[00:06:46] Speaker B: Ah, yes, the sits muscles.
[00:06:49] Speaker A: Supraspinatus, infraspinatus, teres minor, subscapularis. What's their main job? Are they big movers?
[00:06:56] Speaker B: Not primarily movers, no. They're the deep dynamic stabilizers. Their main job as a team is to keep the head of the humerus, the ball of your arm bone, centered perfectly in that shallow socket.
[00:07:07] Speaker A: Like guiding it.
[00:07:08] Speaker B: Exactly. Without them, your big deltoid muscle would just yank the arm bone upwards and jam it.
[00:07:12] Speaker A: Ouch.
Impingement.
[00:07:15] Speaker B: Precisely. So let's break down the team.
[00:07:17] Speaker A: Go for it.
[00:07:17] Speaker B: Supraspinatus.
[00:07:18] Speaker A: Yeah.
[00:07:18] Speaker B: Sits on top of the scapula, runs into the bony arch, attaches to the top of the humerus. Key stabilizer.
And it initiates the first bit of lifting your arm out to the side, maybe the first 30 degrees, and it gets injured.
[00:07:31] Speaker A: A lot.
[00:07:31] Speaker B: Very common, probably because it's always working against gravity and starting that movement. It's under constant load.
[00:07:36] Speaker A: Makes sense. Who's next?
[00:07:38] Speaker B: Infospinatus anteriors minor. They're on the back of the scapula, also attached to the humerus.
[00:07:43] Speaker A: What do they do?
[00:07:44] Speaker B: Also stabilize. But their main movement job is lateral rotation, turning your palm outwards.
[00:07:50] Speaker A: Kick. And the last one, the other?
[00:07:52] Speaker B: S. Subscapularis. This one's on the front side of the scapula, between the scapula and the ribs.
[00:07:56] Speaker A: Ah, hidden away.
[00:07:58] Speaker B: Yeah. It also attaches to the humerus, stabilizes, and its movement is medial rotation, turning your palm inwards.
[00:08:06] Speaker A: So they all work together to keep that ball centered. While bigger muscles move the arm.
[00:08:10] Speaker B: That's the essence of it. And if one gets weak or injured, the others have to compensate, and the whole system can get thrown off.
[00:08:17] Speaker A: We. Which is why just strengthening, say, your deltoid isn't enough for shoulder health.
[00:08:21] Speaker B: Not at all. But it's not just the cuff. We also need muscles controlling the scapula itself, where the socket actually sits.
[00:08:28] Speaker A: Like the serratus anterior.
[00:08:30] Speaker B: Exactly. Serratus anterior runs from your upper ribs around the side to the front edge of your scapula.
[00:08:36] Speaker A: What's its job? It sounds important.
[00:08:38] Speaker B: Hugely important. It basically holds the scapula flat against your rib cage, stops it from winging out.
[00:08:43] Speaker A: Scapular winging. Okay.
[00:08:45] Speaker B: It protracts the scapula, pulls it forward around the ribs, and crucially, it upwardly rotates the scapula.
[00:08:51] Speaker A: Upward rotation. Why is that crucial?
[00:08:53] Speaker B: That upward rotation is essential for getting your arm overhead smoothly and safely. If serratus is weak, overhead movement gets compromised.
[00:09:01] Speaker A: And it sits under some big back muscles.
[00:09:03] Speaker B: Yeah, deep to the lats and pec major, but on top of the subscapularis. Right in that space between ribs and scapula.
[00:09:09] Speaker A: Okay. Another key player for scapular control.
[00:09:12] Speaker B: Pectoralis minor. Smaller chest muscle under the pec major.
[00:09:15] Speaker A: Where does that one go?
[00:09:16] Speaker B: Runs from ribs 3, 4, and 5 up to a little bony hook on the front of the scapula called the coracoid process.
[00:09:22] Speaker A: And it moves the scapula, too?
[00:09:24] Speaker B: Yeah, it pulls it forward, down, and rotates it downward. Kind of the opposite action to serratus in some ways.
[00:09:30] Speaker A: Okay, but why is this one particularly interesting? The manual highlights it.
[00:09:35] Speaker B: Location, location, location. Right underneath pec minor runs the brachial plexus.
[00:09:39] Speaker A: The main nerves for the whole arm.
[00:09:42] Speaker B: Yep. And the main artery and vein, the subclavian vessels, they all pass underneath this muscle.
[00:09:47] Speaker A: Whoa. So if pec minor gets tight.
[00:09:49] Speaker B: If it gets tight, say from rounded shoulders or just tension, it can potentially compress those nerves and blood vessels.
[00:09:56] Speaker A: Causing tingling numbness.
[00:09:58] Speaker B: Exactly. Things like thoracic outlet syndrome are often linked to pec minor tightness. It shows how muscle tension can have far reaching effects beyond just movement.
[00:10:08] Speaker A: Incredible. That's a really powerful connection.
And let's quickly loop back to the trapezius, specifically the upper traps.
[00:10:14] Speaker B: Right. The big diamond shaped muscle on the upper back and neck. Three parts to the upper part.
[00:10:20] Speaker A: Where does that attach?
[00:10:21] Speaker B: Base of the skull ligament down the back of the neck and across the top of the shoulder blade and collarbone.
[00:10:25] Speaker A: It does.
[00:10:25] Speaker B: Lifts the scapula, pulls it back slightly, helps extend and side bend the neck and rotates the head to the opposite side.
[00:10:32] Speaker A: Another one linking head, neck and shoulder.
[00:10:35] Speaker B: Absolutely, yeah. And is notorious for getting tight with stress or compensating for weak deeper muscles. That classic neck and shoulder tension often involves the upper traps working overtime.
[00:10:45] Speaker A: Okay, so much interconnectedness. Let's move down the arm now. Big shoulder movers.
[00:10:49] Speaker B: Right. Acting on the shoulder joint itself and then crossing the elbow. Your main shoulder muscle is the deltoid.
[00:10:54] Speaker A: The cap over the shoulder.
[00:10:55] Speaker B: That's the one. Three parts, front, middle, back, and they.
[00:10:58] Speaker A: All lift the arm.
[00:10:59] Speaker B: The middle part is the prime mover for abduction. Lifting straight out to the side.
But the front part helps flex and internally rotate. The back part helps extend and externally rotate. Very versatile.
[00:11:10] Speaker A: Then the big back muscle, the latissimus dorsi or lats.
[00:11:14] Speaker B: Huge fan shaped muscle. Starts all the way down on your lower back. Fascia, pelvis, lower ribs.
[00:11:19] Speaker A: Wow. Broad origin.
[00:11:21] Speaker B: Yeah. Then the fibers run up and actually twist before they insert on the front of the humerus.
[00:11:25] Speaker A: That twist again. What does it do?
[00:11:28] Speaker B: That twist helps make it a powerful internal rotator.
Along with extending the arm back and pulling it in towards the body.
[00:11:35] Speaker A: Like in pull ups?
[00:11:36] Speaker B: Exactly, pull ups. Rowing, swimming, the lats are major players.
[00:11:40] Speaker A: And on the front, the pectoralis major.
[00:11:42] Speaker B: The main chest muscle also attaches to the humerus.
[00:11:45] Speaker A: Doing what?
[00:11:46] Speaker B: Pulling the arm across the body, rotating it inwards. Medial rotation and flexing it forward. Think push ups. Bench press, hugging.
[00:11:55] Speaker A: Okay. Now muscles that cross both shoulder and elbow.
[00:11:59] Speaker B: Right. The bridge muscles there most famous are biceps brachii and triceps. Brachii.
[00:12:04] Speaker A: Biceps, front of the arm, triceps, back of the arm.
[00:12:06] Speaker B: Pretty much biceps has two heads. Both start on the scapula.
[00:12:10] Speaker A: Both. So it acts on the shoulder too?
[00:12:12] Speaker B: Yep. It helps flex the shoulder slightly, but its main jobs are flexing the Elbow and supitating the forearm, turning the palm up.
[00:12:19] Speaker A: Okay. And triceps.
[00:12:20] Speaker B: Three heads. The long head also starts on the scapula.
[00:12:23] Speaker A: So triceps acts on the shoulder too.
[00:12:25] Speaker B: The long head does. Yes. It helps extend the shoulder and pull the arm adduct. But the main job for all three heads is powerfully extending the elbow, straightening the arm.
[00:12:37] Speaker A: Got it. Are there other important elbow muscles?
[00:12:40] Speaker B: Definitely deeper than the biceps. You have the brachialis.
[00:12:44] Speaker A: Brachialis.
[00:12:45] Speaker B: It sits underneath the biceps, runs from the humerus to the ulna.
[00:12:48] Speaker A: What's special about it?
[00:12:49] Speaker B: It's considered the workhorse of elbow flexion. It purely flexes the elbow regardless of whether your palm is up or down. Biceps is strongest when the palm is up because it also supinates. Brachialis just flexes.
[00:13:02] Speaker A: Ah, interesting distinction.
[00:13:03] Speaker B: And then there's the brachioradialis. This one's fascinating. Functionally.
[00:13:07] Speaker A: Okay, tell me more.
[00:13:08] Speaker B: Runs from the humerus down to the radius bone near the wrist. It flexes the elbow, especially when your forearm is in a neutral thumbs up position.
[00:13:16] Speaker A: Like a hammer curl.
[00:13:17] Speaker B: Exactly. It helps bring the forearm back to neutral from either full pronation or supination.
But here's the kicker from the manual. It says the brachioradialis is essentially turned off or much less active when your forearm is fully pronated. Palm facing away.
[00:13:32] Speaker A: Turned off. So like doing an overhand grip pull up.
[00:13:35] Speaker B: Precisely. And that directly explains why overhand grip pull ups feel harder for many people than underhand grip pull ups.
[00:13:42] Speaker A: Because you lose the help of the.
[00:13:44] Speaker B: Brachioradialis, you lose a significant contribution from it. Yes. Your biceps is also in a less advantageous position for flexing when pronated. So you're relying more heavily on just the brachialis and other muscles.
[00:13:55] Speaker A: That's a fantastic practical insight. I can totally feel that difference.
[00:13:59] Speaker B: It really connects the anatomy to the actual experience of movement.
[00:14:02] Speaker A: And the elbow itself isn't just one joint, right?
[00:14:05] Speaker B: Correct. It's actually three joints working together within one capsule. The the humeral, nar, humerus and ulna. Humeradial humerus and radius. And proximal radial nar, radius and ulna near the elbow.
[00:14:16] Speaker A: Allowing all that complex movement. Bending, straightening, twisting.
[00:14:20] Speaker B: Exactly. Flexion, extension, pronation, supination. It's sophisticated.
[00:14:24] Speaker A: Okay. Bringing it all together. There's one more concept mentioned often in the manual fascia.
[00:14:30] Speaker B: Ah, yes. Connective tissue. Hugely important.
[00:14:33] Speaker A: The manual talks about the thoracolumbar fascia specifically.
[00:14:36] Speaker B: Right. That big diamond sheet of fascia in the lower back.
But it emphasizes its continuity. Continuity Meaning it's not isolated. It connects upwards, blending with fascia all the way up to the neck and even the cranium and downwards towards the sacrum and pelvis. It's part of a body wide web.
[00:14:54] Speaker A: Like a full body stocking under the skin.
[00:14:56] Speaker B: That's a common analogy. Yeah. It surrounds and connects muscles, bones, organs, everything.
[00:15:02] Speaker A: So what's the implication of that continuity?
[00:15:04] Speaker B: It means everything is mechanically linked. Tightness or restriction in one spot like that thoracolumbar fascia can potentially transmit tension and affect movement or sensation in a completely different area.
Neck pain could have a link to lower back stiffness through this fascial chain.
[00:15:21] Speaker A: Wow. So you can't just look at the sore spot in isolation?
[00:15:24] Speaker B: Ideally, no. You need to consider the whole interconnected system. Fascia really drives home that holistic view.
[00:15:30] Speaker A: So wrapping this all up, we what's the big takeaway?
[00:15:33] Speaker B: For someone listening, I think it's understanding the incredible complexity, but also the beautiful interconnectedness of your upper body.
[00:15:40] Speaker A: Yeah. From those deep little stabilizers like longus.
[00:15:42] Speaker B: Cauli and the suboccipital, to the sensory input they provide.
The common culprits like levator scapula, the functional insights like with the brachioradialis and.
[00:15:52] Speaker A: That underlying fascial web tying it all together.
[00:15:55] Speaker B: Exactly. Knowing these layers and links helps you understand why your body moves the way it does, or why you might feel discomfort.
[00:16:03] Speaker A: It's empowering knowledge.
[00:16:04] Speaker B: Absolutely. Understanding stabilizer versus mobilizer roles, how nerves run through muscles, how fascia connects distant parts. It changes how you think about exercise, posture, everything.
[00:16:16] Speaker A: So next time you feel something, a twinge in the neck, shoulder stiffness, don't.
[00:16:20] Speaker B: Just focus right there. Think bigger picture.
[00:16:22] Speaker A: Could it be related to deep stabilizers? Is a global mover compensating?
How's my grip affecting my elbow and shoulder? Is my posture influencing my pec minor?
[00:16:32] Speaker B: Asking those questions, looking for those connections that can lead to real breakthroughs in how you feel and move.
[00:16:38] Speaker A: It really encourages a deeper curiosity about your own body.
[00:16:42] Speaker B: That's the hope. Explore how all these parts work together for you.
