Chapter Text
“Pretty sure that I fucking hate this class. I’m not even a science major.” Sanji throws his bag onto the couch adducting his arm with the pectoantebrachialis. “Don’t tell me. It originates from the manubrium of the sternum and inserts at the proximal end of the ulna.”
“We don’t actually have this muscle though. It’s just in cats.”
“Where is the pectoralis major that flexes and extends the humerus?” Zoro hints at his collarbone.
“I know it inserts into the bicipital groove of the humerus and originates from the clavicular head.”
“Now we’re onto rib cage origins. This muscle stabilizes the scapula and raises the ribs during inspiration.”
“It’s the pectoralis minor that comes from the 3rd to 5th ribs and inserts into the coracoid process of the scapula. It’s the hook thing that is where the clavicle joins at.”
Sanji contralaterally rotates his torso using his external obliques which originated from the 5th to 12th ribs. “Where does the external obliques insert? There’s three points like those earrings you have.”
“The iliac crest, pubic tubercle, and lines alba.” Zoro replies smugly. “Where’s the clavotrapezius?”
“I know it originates from the lambdoidal ridge of the skull and inserts into the raphe of the clavicle. You know our professor doesn’t even really know where that is? He keeps pointing somewhere in the medial end of the clavicle.”
Zoro flexes his forearm, turns his head and extends his humerus forward to show the action.
“What originates from C2 to T1-4 and inserts into the metacromion and scapula spine?”
“The acromiotrapezius that will draw your scapula together medially. It’s like when you wake up in the morning and get that crick out of your back.”
“Maybe because you’re getting old there cook. Now what draws the scapula dorsally?
“Don’t tell me. It’s the spinotrapezius. T1-4 to T11-13? And it inserts into the scapular spine which is the dividing line between two muscles but we don’t ned to talk about that yet.”
Zoro pulls off the sweaty shirt to reveal his latissimus dorsi muscles which moved as he pulled his humerus caudodorsally. “Give me origin and insertion.”
“They’re in T4-5 to L6 and insert on the medial shaft of the humerus.” Sanji raises his eyes brows when Zoro rolls his eyes. “Ah, that reference.”
“What draws your scapula cranially and inserts into the metacromion of the scapula?”
“The levator scapulae ventralis originates from the transverse process of the atlas and the occipital bone.”
Sanji's getting really sick of these muscles and bones. He has two cooking practicals in the same week but they're not horrid. The next two muscles are practically the same and if he thinks of the name he can probably get them right.
"The acromiodeltoid and spinodeltoid both extend and rotate the humerus. They also insert into the deltoid ridge of the humerus. The only difference is that the aromiodeltoid inserts into the outer surface of the spinodeltoid and the branchialis anticus."
"Did you figure out how to remember their origins?"
"You've just gotta know that they originate from the scapula. And then from there you know that one is the acromion and the other is the spine."
"Do you ever wonder why one muscle can do so many things?"
"Are you talking about the clavodeltoid? That's because of it's location and how it originates from the raphe of the clavicle and inserts into the ulna under the semilunar notch. Please perform it's functions for me."
Zoro extends his humerus and flexes his forearm. He turns his head to Sanji slowly, so slowly that he can see the muscle twisting. "Your turn cook, where's the teres major and what does it do?"
"How do you go about being sexy while adducting your humerus? Forget I said anything, it comes from the inferior angle of the scapula and inserts into the intertubercular sulcus of the humerus. Pretty sure that I have no fucking idea what I just said."
"What's the muscle underneath the scapular in the subscapular fossa that medially rotates the humerus?"
"That would be the subscapularis. And it's in the lesser tubercle of the humerus."
"I'm gonna take a shower. I smell like the gym." Zoro had never put his shirt back on and just pulled his shorts off right there to chuck them at Sanji. "I'll let you feel my rectus abdominis later."
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It's Sanji's turn to be mildly excited for an anatomy review session because there's probably no one he knows with torso muscles as toned as Zoro's. They start with the xiphihumeralis that originates from the xiphoid process of the sternum and inserts into the humerus.
"Can you just sit on the table? I don't feel like squatting down to look at your abs. Don't you even start. I have abs."
Zoro laughs and hops on their kitchen counter. Sanji makes a note to lysol it later. "Okay, so internal obliques and the tansversus abdominis both compress the abdomen, but the internals also rotate the vertebral column. And they originate from the iliac crest. Do you remember where that is?"
"I can visualize it but it's the part of your hip that you can feel right? Both insert into the linea alba but the transversus also inserts into the xiphoid process of the sternum." Sanji presses on the lowest part of Zoro's sternum.
"This is the part where you get to feel my godly rectus abdominis."
"Oh, shut up. Do you fucking have 8 abs?"
"It originates from the crest of the pubic bone and inserts into the 5th and 7th ribs and the xiphoid process. It flexes the lumbar spine. So your lower back if you have trouble remembering it."
"Come over here you bag of bones. And shirt off."
"Why... oh the erectorae spinae. That goes fromspinous processes of T9-12 and inserts into T1 and 2." Sanji straightens out his back for Zoro to see just how long his torso is.
"Wait, can you stand up straight again? We'll do the scalenus and external intercostals. The scalenus elevates your fist and second ribs which inserts where as well. It originates from the cervical vertebrae."
"If I breathe in, you can see my ribcage, right? And that's where the external intercostals are. They come from the lower border of the ribs and insert into the upper boarder of the posterior rib."
"You can put your shirt back on."
"You didn't need to tell me." Sanji pokes his head through the hole of the thin black shirt.
"Time for the rhomboideus major and minor that draws the vertebral border of the scapula medially and dorsally."
"It originates from the spines of T1-4. The minor inserts into the vertebral border of the scapula and the major is at the inferior angle."
"What about the capitis which draws the dorsal border of the scapula forward?"
Sanji feels around on his back. "I think it originates from the lamboidal ridge of the skull and inserts into the vertebral border of the scapula where the minor does as well."
Zoro extends his arm again and then flexes it to show the action of the supraspinatus and infraspinatus. "They originate from their respective fossa of the scapula. You get to name the insertions."
"They're both on the greater tuberosity of the humerus but the infra is on the lateral part."
"We've got one last one and we're done with the trunk. What muscle is underneath of the clavotrapezius and originates from the spinous processes of the cervical vertebrae?"
"That would be the splenius that inserts into the mastoid process of the temporal and occipital bones. It extends, rotates and laterally flexes the head."
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“I’m not sure if I’m going to have to punch you in the neck or something in order to learn these muscles.”
“Let’s just use the person with the longer neck. Which so happens to be me.” Sanji straightens out his neck for easy viewing.
“First one up is the sternomastoid that turns the head, and depresses the head and neck. Whatever the fuck that means.”
“It starts at the manubrium of the sternum and goes into the mastoid process and lambdoidal ridge. Those are places in the skull that we have yet to learn.”
“Now if you go more to the center of the neck you’ll see the sternohyoid which draws the hyoid caudally.”
Sanji pokes around at the middle of his neck. “It originates from the first costal cartilage and inserts into the body of the hyoid.”
Zoro leans forward, takes two fingers, and pushes Sanji’s chin upwards to show the digastrics that depress the mandible. “Origin and insertion?”
“Ummm, the jugular process of the occipital and the mastoid process of temporal and it inserts into the ventral border of the mandible. Can you let go?”
“Only if you tell me what inserts into the median raphe and originates from the medial surface of the mandible.”
“It’s the myohyloid and it raises the floor of the mouth to draw the hyoid back. Are we almost done yet? I still have to make dinner.”
“These two muscles elevate your mandible.”
“The masseter and the temporalis! But that’s pretty much the only thing that’s similar about them. Oh, wait, they do both insert into the mandible. The masseter is in the ventral border and the carotid fossa, and the other is in the coronoid process.”
“We’re getting there. The ventral border of the zygomatic arch is where the masseter originates and the temporal fossa of the parietal, squamosal, and frontal is where the temporalis originates.”
“Where exactly is the raphe of the clavicle? Is it that part that sticks out and where the cleidomastoid also inserts into?”
“Pretty much. It originates from the mastoid process of the temporal and rotates your head. And now we’ve got the sternothyroid that depresses the thyroid.”
“I know that comes from the manubrium of the sternum and I think inserts into the thyroid cartilage.”
“If that one depresses your thyroid, then what elevates it?”
“The thyrohyoid! It starts from the thyroid cartilage and inserts into the hyoid bone. Done! We are finally done.”