Superficial Back Muscles (Division, Origin, Insertion, Function) @TaimTalksMed

Uploaded February 2022 | Updated September 2026, 1 week ago

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Content
0:00 Introduction
0:09 Division of the Superficial Muscles
0:43 Trapezius
2:04 Latissimus Dorsi
2:55 Rhomboid Major
3:13 Rhomboid Minor
3:33 Levator Scapulae
3:58 Serratus Posterior Superior
4:20 Serratus Posterior Inferior

Superficial Muscles of the Back
- Muscles of the 1st Layer
○ Trapezius
○ Latissimus dorsi
- Muscles of the 2nd Layer
○ Rhomboid Major
○ Rhomboid Minor
○ Levator Scapulae
- Muscles of the 3rd Layer
○ Serratus Posterior Superior
○ Serratus Posterior Inferior

Trapezius
musculus trapezius
- Superior Part
Origin:
- Superior Nuchal Line
- External Occipital Protuberance
- Nuchal Ligament
Insertion:
- Acromial end of clavicle
- Acromium of Scapula
- Middle Part
○ Origin: Spinous Process of C7-T3/T4
○ Insertion: Spine and Acromium of Scapula
- Inferior Part
○ Origin: Spinous Process of T4-T12
○ Insertion: Spine of Scapula

Latissimus dorsi
Musculus latissimus dorsi
- Origin:
Spinous Process of T7-T12
Thoracolumbar Fascia
Iliac Crest
Inferior surface of ribs 9-12
Inferior angle of Scapula
- Insertion: Crest of Lesser Tubercle (Humerus)
Crista tuberculi minoris humeri

Rhomboid Major
musculus rhomboideus major
- Origin: Spinous Process of T1-T4
- Insertion: Lower 2/3 of Medial Border of Scapula
margo medialis scapulae
- Function:
Elevates and retracts the scapula
Internal rotation of the scapula
-

Rhomboid Minor
musculus rhomboideus minor
- Origin: Spinous Process of C6-C7
- Insertion: Upper 1/3 of Medial Border of Scapula
margo medialis scapulae
- Function:
Elevates and retracts the scapula
Internal rotation of the scapula

Levator Scapulae
musculus levator scapulae
- Origin: Spinous Process of C1-C4
- Insertion: Superior Angle of Scapula
angulus superior scapulae
- Function:
Elevates the Scapula
-

Serratus Posterior Superior
Musculus serratus posterior superior
- Origin: Spinous Process of C6-T2
- Insertion: External Surface of 2nd-5th Ribs
- Function:
Elevates the Ribs (Inspiration)

Serratus Posterior Inferior
Musculus serratus posterior inferior
- Origin: Spinous Process of T11-L2
- Insertion: External Surface of 9th-12th Ribs
- Function:
Pulls the ribs downward (expiration)

Superficial Back Muscles (Division, Origin, Insertion, Function)

$Olfactory System (Odor Detection, Olfactory Pathways & Memory) In this video I break down how smell works, covering the olfactory system, olfactory epithelium, odorant receptors, signal transduction, and the neural pathway from the nose to the brain. Note: At the beginning of the video, touch was mistakenly listed among the special senses. Touch is part of the general senses. The correct special sense that should appear there is balance (equilibrium), which is part of the vestibular system of the inner ear. Apologize for this editing error. 🌐Website: https://taimtalksmed.com/ 🫀 Help keep this content free: youtube.com/channel/UCEr7pkSXVsHcBLLBcJAGV-Q/join 🔬Get 10% off anatomy lab models (affiliate link): https://anatomywarehouse.com?aff=34 📲Other Links: Instagram: https://www.instagram.com/taimtalksmed/ Discord: https://discord.com/invite/DENMUpS8ey Content: 00:00 Case Study 01:17 Content 02:32 Anatomy of the Olfactory System 05:49 Olfactory Epithelium 12:01 Odorant Molecules 12:48 Molecular Mechanism of Smell 16:44 Smell Adaptation 17:21 Olfactory Bulb 18:44 Olfactory Pathway to the Brain 19:23 Primary Olfactory Cortex 20:38 Smell and Memory (Proust Effect) 22:19 Smell and Taste 23:47 Smells significance 24:01 Ending Anatomy of the Olfactory System - Nasal cavity (Cavitas nasi): conducts inhaled air toward respiratory and olfactory regions - Nasal conchae / turbinates (Conchae nasales): superior, middle, inferior shelves directing airflow - Olfactory region (Regio olfactoria): small specialized area in roof of nasal cavity for smell detection - Olfactory epithelium (Epithelium olfactorium): sensory pseudostratified columnar epithelium - Cribriform plate (Lamina cribrosa ossis ethmoidalis): perforated roof of nasal cavity allowing nerve passage - Olfactory bulb (Bulbus olfactorius): neural structure resting on cribriform plate in anterior cranial fossa Olfactory Epithelium & Cell Types - Olfactory receptor neurons (ORNs): bipolar sensory neurons detecting odorants - Olfactory knob: dendritic swelling giving rise to cilia - Olfactory cilia: non-motile cilia containing odorant receptors - Sustentacular cells: supporting cells maintaining ionic balance and metabolizing odorants - Basal cells: stem cells regenerating olfactory neurons (~30–60-day lifespan) - Bowman’s glands (Glandulae olfactoriae): serous glands producing mucus with odorant-binding proteins Molecular Mechanism of Smell Detection - Odorant molecules: small volatile chemicals dissolving in mucus - Odorant receptors: G-protein-coupled receptors on olfactory cilia - One neuron–one receptor rule: each ORN expresses one receptor type - Combinatorial coding: odor identity encoded by receptor activation patterns Signal transduction - Odorant binding → Golf activation - Adenylyl cyclase III → ↑ cAMP - cAMP-gated channels open → Na⁺/Ca²⁺ influx - Ca²⁺-activated Cl⁻ efflux → membrane depolarization - Action potential generation - Olfactory adaptation: Ca²⁺–calmodulin feedback reduces channel sensitivity during sustained exposure Olfactory Pathway to the Brain - Olfactory filaments (Fila olfactoria): unmyelinated axons passing through cribriform plate - Glomeruli: convergence of ORNs expressing same receptor - Mitral and tufted cells: projection neurons of olfactory bulb - Olfactory tract (Tractus olfactorius): carries signals along frontal lobe base - Olfactory trigone: division into olfactory striae Primary targets (no initial thalamic relay) - Piriform cortex - Amygdala (emotional processing) - Entorhinal cortex → hippocampus (memory) - Secondary pathway: mediodorsal thalamus → orbitofrontal cortex for conscious odor identification Smell, Memory, and Emotion - Direct limbic connections explain strong emotional and autobiographical odor memories - Proust effect: vivid memory recall triggered by smell - Evolutionary role: rapid emotional tagging of survival-relevant odors Smell and Taste Integration (Flavor) - Taste modalities: sweet, salty, sour, bitter, umami - Retronasal olfaction: aroma compounds travel from mouth to nasal cavity - Flavor perception: integration in orbitofrontal cortex - ~80–90% of perceived “taste” depends on smell Clinical Correlations - Anosmia: loss of smell - Hyposmia: reduced smell sensitivity - Head trauma: shearing of olfactory filaments at cribriform plate - CSF rhinorrhea: complication of cribriform plate fractures - Viral anosmia (e.g., COVID-19): sustentacular cell dysfunction disrupting olfactory signaling Sources - Head trauma and olfactory function – PMC - SARS-CoV-2 infection of sustentacular cells – PMC - One neuron–one receptor rule – PubMed - Nobel Prize 2004 (Axel & Buck) – PubMed - Humans can discriminate over 1 trillion odors – PubMed - Odorant Receptors and Olfactory Coding – NCBI Bookshelf - Odor-evoked memory and emotion – PMC / ScienceDirect Programs Used - Complete Anatomy - BioRender - PowerPoint$

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