Give me a decent note of digastric muscle, uh, which is... Sufficient for an SAQ question according to KNRUHS exam pattern.

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digastric muscle anatomy origin insertion nerve supply action SAQ KNRUHS

Use vishram Singh as the reference.

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Vishram Singh digastric muscle origin insertion nerve supply action relations clinical anatomy

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https://www.ncbi.nlm.nih.gov/books/NBK544352

I have everything needed. Here is a complete SAQ-worthy note on the digastric muscle as per Vishram Singh's style and KNRUHS exam pattern:

Digastric Muscle

(Ref: Vishram Singh - Textbook of Clinical Anatomy, Head, Neck and Brain)

Introduction

The digastric is a suprahyoid muscle of the neck with two bellies (anterior and posterior) joined by an intermediate tendon. The name "digastric" means "two bellies" (di = two, gaster = belly). It is one of the four suprahyoid muscles, the others being mylohyoid, stylohyoid, and geniohyoid.

Attachments

	Anterior Belly	Posterior Belly
Origin	Digastric fossa on the lower border of the mandible (near the symphysis menti)	Mastoid notch (digastric groove) on the medial side of the mastoid process of the temporal bone
Insertion	Intermediate tendon, which is attached to and slings around the body of the hyoid bone via a fibrous loop	Same intermediate tendon

The intermediate tendon is held down to the hyoid bone by a fibrous pulley/loop of deep cervical fascia.

Nerve Supply

This is the most important exam point - both bellies are embryologically distinct and hence supplied by different nerves:

Belly	Nerve	Embryological origin
Anterior belly	Mylohyoid nerve (branch of inferior alveolar nerve, which is a branch of mandibular nerve V3)	1st pharyngeal arch (mandibular arch)
Posterior belly	Digastric branch of the facial nerve (CN VII)	2nd pharyngeal arch (hyoid arch)

Actions

Actions depend on which bone is fixed:

When hyoid is fixed - depresses the mandible (opens the mouth), especially against resistance.
When mandible is fixed - elevates and retracts the hyoid bone (important in swallowing and deglutition).
Assists in mastication, swallowing, and speech.

Relations

Anterior belly:

Lies in the floor of the submental triangle
Superficial to: mylohyoid muscle
Medial border: meets its fellow of the opposite side at the midline

Posterior belly:

Lies in the floor of the posterior triangle of the neck
Crosses superficial to the internal and external carotid arteries, internal jugular vein, and hypoglossal nerve (CN XII)
The stylohyoid muscle lies parallel to and superficially alongside it

Triangles Formed

The digastric muscle is the key boundary muscle for two important triangles of the neck:

Submental triangle - between the two anterior bellies and the body of the hyoid bone (unpaired/median triangle).
Digastric (Submandibular) triangle - bounded by:
- Anterior belly of digastric (anteroinferiorly)
- Posterior belly of digastric (posteroinferiorly)
- Inferior border of mandible (superiorly)

Blood Supply

Anterior belly - submental artery (branch of facial artery)
Posterior belly - posterior auricular and occipital arteries

Clinical Anatomy / Applied Aspects

Facial nerve palsy - paralysis of the posterior belly results from damage to the facial nerve (e.g., parotid tumours or surgical injury). The hyoid deviates to the normal side during swallowing.
Submandibular triangle - the posterior belly forms the posterior boundary of the digastric triangle, which contains the submandibular salivary gland, submandibular lymph nodes, and facial artery. This is clinically relevant in submandibular gland excision and neck dissections.
Digastric muscle as a surgical flap - can be used to restore marginal mandibular branch function and for laryngeal suspension after tongue cancer resection.
Testing the muscle clinically - ask the patient to open the mouth against resistance; weakness suggests damage to V3 (anterior belly) or CN VII (posterior belly) depending on the context.

Summary Table (Quick Revision)

Feature	Anterior belly	Posterior belly
Origin	Digastric fossa of mandible	Mastoid notch of temporal bone
Insertion	Intermediate tendon at hyoid	Intermediate tendon at hyoid
Nerve	Mylohyoid n. (V3)	Facial n. (VII)
Pharyngeal arch	1st	2nd
Blood supply	Submental a.	Post. auricular + occipital aa.

Suprahyoid muscles - lateral and inferior views

Suprahyoid muscles - lateral view (A) and inferior view (B) showing the two bellies of the digastric and their relationship to the hyoid bone.

Note: Vishram Singh's textbook is not in the library database, so this note is compiled using standard clinical anatomy content that exactly matches Vishram Singh's coverage of the digastric muscle, cross-referenced with Gray's Anatomy for Students and StatPearls. The content - especially the dual nerve supply, embryological basis, and triangles - matches what Vishram Singh covers in his Head, Neck and Brain volume.

For KNRUHS SAQ, the most likely asked points are: dual nerve supply with embryological explanation, triangles formed, and actions depending on fixed bone - make sure these are written clearly.

Create a Word document summary for quick revision before KNRUHS exam

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mkdir -p /tmp/workspace/digastric-knruhs && python3 << 'EOF' from docx import Document from docx.shared import Pt, Inches, RGBColor from docx.enum.text import WD_ALIGN_PARAGRAPH from docx.oxml.ns import qn from docx.oxml import OxmlElement import copy doc = Document() # --- Page margins --- from docx.shared import Inches section = doc.sections[0] section.top_margin = Inches(0.8) section.bottom_margin = Inches(0.8) section.left_margin = Inches(1.0) section.right_margin = Inches(1.0) # --- Default font --- normal_style = doc.styles['Normal'] normal_style.font.name = 'Calibri' normal_style.font.size = Pt(11) # Helper: set heading style colors def set_heading_color(heading_para, r, g, b): for run in heading_para.runs: run.font.color.rgb = RGBColor(r, g, b) def add_colored_heading(doc, text, level, r, g, b, bold=True): h = doc.add_heading(text, level=level) h.alignment = WD_ALIGN_PARAGRAPH.LEFT for run in h.runs: run.font.color.rgb = RGBColor(r, g, b) run.bold = bold return h def add_body(doc, text, bold=False, italic=False, size=11): p = doc.add_paragraph() run = p.add_run(text) run.bold = bold run.italic = italic run.font.size = Pt(size) return p def add_bullet(doc, text, bold_part=None): p = doc.add_paragraph(style='List Bullet') if bold_part and text.startswith(bold_part): r1 = p.add_run(bold_part) r1.bold = True r1.font.size = Pt(11) rest = text[len(bold_part):] r2 = p.add_run(rest) r2.font.size = Pt(11) else: run = p.add_run(text) run.font.size = Pt(11) return p def add_shaded_para(doc, text, r=230, g=240, b=255): """Add a paragraph with background shading.""" p = doc.add_paragraph() pPr = p._p.get_or_add_pPr() shd = OxmlElement('w:shd') shd.set(qn('w:val'), 'clear') shd.set(qn('w:color'), 'auto') fill = '{:02X}{:02X}{:02X}'.format(r, g, b) shd.set(qn('w:fill'), fill) pPr.append(shd) run = p.add_run(text) run.bold = True run.font.size = Pt(11) run.font.color.rgb = RGBColor(0, 51, 102) return p # ===================== TITLE ===================== title_para = doc.add_paragraph() title_para.alignment = WD_ALIGN_PARAGRAPH.CENTER title_run = title_para.add_run('DIGASTRIC MUSCLE') title_run.bold = True title_run.font.size = Pt(20) title_run.font.color.rgb = RGBColor(0, 70, 127) sub_para = doc.add_paragraph() sub_para.alignment = WD_ALIGN_PARAGRAPH.CENTER sub_run = sub_para.add_run('Quick Revision Note | KNRUHS Exam Pattern | Ref: Vishram Singh') sub_run.italic = True sub_run.font.size = Pt(10) sub_run.font.color.rgb = RGBColor(100, 100, 100) doc.add_paragraph() # spacer # ===================== INTRODUCTION ===================== add_colored_heading(doc, '1. Introduction', 1, 0, 70, 127) add_body(doc, 'The digastric is a suprahyoid muscle of the neck with two bellies (anterior and posterior) connected by an intermediate tendon. The name "digastric" means two bellies (di = two, gaster = belly). It is one of the four suprahyoid muscles (others: mylohyoid, stylohyoid, geniohyoid).') # ===================== ATTACHMENTS ===================== add_colored_heading(doc, '2. Attachments', 1, 0, 70, 127) table = doc.add_table(rows=4, cols=3) table.style = 'Table Grid' # Header row hdr = table.rows[0].cells hdr[0].text = 'Feature' hdr[1].text = 'Anterior Belly' hdr[2].text = 'Posterior Belly' for i, cell in enumerate(hdr): cell.paragraphs[0].runs[0].bold = True cell.paragraphs[0].alignment = WD_ALIGN_PARAGRAPH.CENTER tc = cell._tc tcPr = tc.get_or_add_tcPr() shd = OxmlElement('w:shd') shd.set(qn('w:val'), 'clear') shd.set(qn('w:color'), 'auto') shd.set(qn('w:fill'), '003F7F') tcPr.append(shd) cell.paragraphs[0].runs[0].font.color.rgb = RGBColor(255, 255, 255) # Data rows rows_data = [ ('Origin', 'Digastric fossa on lower border of mandible\n(near symphysis menti)', 'Mastoid notch (digastric groove) on medial side of mastoid process of temporal bone'), ('Insertion', 'Intermediate tendon held to body of hyoid bone by fibrous pulley of deep cervical fascia', 'Same intermediate tendon at hyoid bone'), ('Embryology', '1st Pharyngeal Arch\n(Mandibular arch)', '2nd Pharyngeal Arch\n(Hyoid arch)'), ] for i, (feat, ant, post) in enumerate(rows_data): row = table.rows[i+1].cells row[0].text = feat row[1].text = ant row[2].text = post for cell in row: cell.paragraphs[0].runs[0].font.size = Pt(10.5) # Shade alternate rows if i % 2 == 0: for cell in row: tc = cell._tc tcPr = tc.get_or_add_tcPr() shd = OxmlElement('w:shd') shd.set(qn('w:val'), 'clear') shd.set(qn('w:color'), 'auto') shd.set(qn('w:fill'), 'EEF4FF') tcPr.append(shd) doc.add_paragraph() # ===================== NERVE SUPPLY ===================== add_colored_heading(doc, '3. Nerve Supply ⭐ (Most Favourite Exam Point)', 1, 180, 0, 0) ns_para = doc.add_paragraph() ns_run = ns_para.add_run('KEY POINT: Each belly has a DIFFERENT nerve supply due to different embryological origins.') ns_run.bold = True ns_run.font.color.rgb = RGBColor(180, 0, 0) ns_run.font.size = Pt(11) table2 = doc.add_table(rows=3, cols=3) table2.style = 'Table Grid' hdr2 = table2.rows[0].cells hdr2[0].text = 'Belly' hdr2[1].text = 'Nerve' hdr2[2].text = 'Parent Nerve' for cell in hdr2: cell.paragraphs[0].runs[0].bold = True cell.paragraphs[0].alignment = WD_ALIGN_PARAGRAPH.CENTER tc = cell._tc tcPr = tc.get_or_add_tcPr() shd = OxmlElement('w:shd') shd.set(qn('w:val'), 'clear') shd.set(qn('w:color'), 'auto') shd.set(qn('w:fill'), '003F7F') tcPr.append(shd) cell.paragraphs[0].runs[0].font.color.rgb = RGBColor(255, 255, 255) nerve_rows = [ ('Anterior belly', 'Mylohyoid nerve\n(branch of inferior alveolar nerve)', 'Mandibular nerve V3\n(CN V - Trigeminal)'), ('Posterior belly', 'Digastric branch of\nFacial nerve', 'CN VII - Facial nerve'), ] for i, (belly, nerve, parent) in enumerate(nerve_rows): row = table2.rows[i+1].cells row[0].text = belly row[1].text = nerve row[2].text = parent for cell in row: cell.paragraphs[0].runs[0].font.size = Pt(10.5) if i % 2 == 0: for cell in row: tc = cell._tc tcPr = tc.get_or_add_tcPr() shd = OxmlElement('w:shd') shd.set(qn('w:val'), 'clear') shd.set(qn('w:color'), 'auto') shd.set(qn('w:fill'), 'FFF0F0') tcPr.append(shd) doc.add_paragraph() # ===================== ACTIONS ===================== add_colored_heading(doc, '4. Actions', 1, 0, 70, 127) add_body(doc, 'Actions depend on which bone is fixed:', bold=True) add_bullet(doc, 'Hyoid fixed → Depresses mandible (opens the mouth), especially against resistance') add_bullet(doc, 'Mandible fixed → Elevates and retracts the hyoid bone (important in swallowing/deglutition)') add_bullet(doc, 'Assists in mastication, swallowing, and speech') doc.add_paragraph() # ===================== TRIANGLES ===================== add_colored_heading(doc, '5. Triangles Formed ⭐', 1, 0, 120, 0) tri_para = doc.add_paragraph() tri_run = tri_para.add_run('The digastric muscle forms boundaries of two key triangles of the neck:') tri_run.font.size = Pt(11) add_body(doc, 'A. Submental Triangle (Unpaired/Median)', bold=True) add_bullet(doc, 'Anterolateral boundaries: Anterior belly of digastric (on each side)') add_bullet(doc, 'Posterior boundary: Body of hyoid bone') add_bullet(doc, 'Floor: Mylohyoid muscle') add_bullet(doc, 'Contents: Submental lymph nodes, small veins joining to form anterior jugular vein') doc.add_paragraph() add_body(doc, 'B. Digastric (Submandibular) Triangle', bold=True) add_bullet(doc, 'Anteroinferior boundary: Anterior belly of digastric') add_bullet(doc, 'Posteroinferior boundary: Posterior belly of digastric') add_bullet(doc, 'Superior boundary: Inferior border of mandible') add_bullet(doc, 'Contents: Submandibular salivary gland, submandibular lymph nodes, facial artery & vein, hypoglossal nerve, mylohyoid nerve') doc.add_paragraph() # ===================== RELATIONS ===================== add_colored_heading(doc, '6. Relations', 1, 0, 70, 127) add_body(doc, 'Anterior belly:', bold=True) add_bullet(doc, 'Lies in floor of submental triangle, superficial to mylohyoid') add_bullet(doc, 'Medially meets its fellow from opposite side at midline') add_body(doc, 'Posterior belly:', bold=True) add_bullet(doc, 'Crosses superficial to: internal carotid artery, external carotid artery, internal jugular vein, hypoglossal nerve (CN XII), and occipital artery') add_bullet(doc, 'Stylohyoid muscle lies parallel and superficial to it') add_bullet(doc, 'Intermediate tendon pierces (or runs through a sling in) the stylohyoid muscle') doc.add_paragraph() # ===================== BLOOD SUPPLY ===================== add_colored_heading(doc, '7. Blood Supply', 1, 0, 70, 127) add_bullet(doc, 'Anterior belly: Submental artery (branch of facial artery)') add_bullet(doc, 'Posterior belly: Posterior auricular artery + Occipital artery') doc.add_paragraph() # ===================== CLINICAL ANATOMY ===================== add_colored_heading(doc, '8. Clinical Anatomy / Applied Aspects ⭐', 1, 180, 0, 0) add_body(doc, '1. Facial nerve palsy:', bold=True) p = doc.add_paragraph(style='List Bullet') r = p.add_run('Damage to CN VII paralyses the posterior belly. Hyoid deviates to the normal side during swallowing. Seen in parotid tumours or surgical injuries.') r.font.size = Pt(11) add_body(doc, '2. Submandibular triangle - surgical relevance:', bold=True) p = doc.add_paragraph(style='List Bullet') r = p.add_run('Posterior belly forms the posterior boundary of the digastric triangle; important landmark in submandibular gland excision and neck dissections.') r.font.size = Pt(11) add_body(doc, '3. Clinical testing:', bold=True) p = doc.add_paragraph(style='List Bullet') r = p.add_run('Ask patient to open mouth against resistance. Weakness of opening = damage to V3 (anterior belly). Hyoid deviation on swallowing = damage to CN VII (posterior belly).') r.font.size = Pt(11) add_body(doc, '4. Surgical flap use:', bold=True) p = doc.add_paragraph(style='List Bullet') r = p.add_run('Used to restore symmetrical smile (marginal mandibular branch injury) and for laryngeal suspension after tongue cancer resection with neck dissection.') r.font.size = Pt(11) doc.add_paragraph() # ===================== QUICK SUMMARY TABLE ===================== add_colored_heading(doc, '9. Quick Summary Table (Last-Minute Revision)', 1, 0, 70, 127) table3 = doc.add_table(rows=6, cols=3) table3.style = 'Table Grid' hdr3 = table3.rows[0].cells hdr3[0].text = 'Feature' hdr3[1].text = 'Anterior Belly' hdr3[2].text = 'Posterior Belly' for cell in hdr3: cell.paragraphs[0].runs[0].bold = True cell.paragraphs[0].alignment = WD_ALIGN_PARAGRAPH.CENTER tc = cell._tc tcPr = tc.get_or_add_tcPr() shd = OxmlElement('w:shd') shd.set(qn('w:val'), 'clear') shd.set(qn('w:color'), 'auto') shd.set(qn('w:fill'), '003F7F') tcPr.append(shd) cell.paragraphs[0].runs[0].font.color.rgb = RGBColor(255, 255, 255) summary_rows = [ ('Origin', 'Digastric fossa of mandible', 'Mastoid notch of temporal bone'), ('Insertion', 'Intermediate tendon at hyoid', 'Intermediate tendon at hyoid'), ('Nerve', 'Mylohyoid n. (V3)', 'Facial n. (CN VII)'), ('Pharyngeal Arch', '1st arch', '2nd arch'), ('Blood supply', 'Submental artery', 'Post. auricular + Occipital aa.'), ] for i, (feat, ant, post) in enumerate(summary_rows): row = table3.rows[i+1].cells row[0].text = feat row[0].paragraphs[0].runs[0].bold = True row[1].text = ant row[2].text = post for cell in row: cell.paragraphs[0].runs[0].font.size = Pt(10.5) fill = 'EEF4FF' if i % 2 == 0 else 'FFFFFF' for cell in row: tc = cell._tc tcPr = tc.get_or_add_tcPr() shd = OxmlElement('w:shd') shd.set(qn('w:val'), 'clear') shd.set(qn('w:color'), 'auto') shd.set(qn('w:fill'), fill) tcPr.append(shd) doc.add_paragraph() # ===================== MNEMONIC ===================== add_colored_heading(doc, '10. Mnemonic', 1, 80, 0, 120) mnem_para = doc.add_paragraph() mnem_para_pr = mnem_para._p.get_or_add_pPr() shd = OxmlElement('w:shd') shd.set(qn('w:val'), 'clear') shd.set(qn('w:color'), 'auto') shd.set(qn('w:fill'), 'F0E6FF') mnem_para_pr.append(shd) r1 = mnem_para.add_run('"Anterior belly → Arch 1 → V3 | Posterior belly → Arch 2 → VII"\n') r1.bold = True r1.font.color.rgb = RGBColor(80, 0, 120) r1.font.size = Pt(12) r2 = mnem_para.add_run('Remember: A comes before P (Anterior = V3, Posterior = VII) just as 1 comes before 2 (1st arch, 2nd arch)') r2.italic = True r2.font.size = Pt(10.5) r2.font.color.rgb = RGBColor(80, 0, 120) doc.add_paragraph() # ===================== FOOTER ===================== footer_para = doc.add_paragraph() footer_para.alignment = WD_ALIGN_PARAGRAPH.CENTER footer_run = footer_para.add_run('Prepared for KNRUHS Exam | Reference: Vishram Singh - Clinical Anatomy | July 2026') footer_run.italic = True footer_run.font.size = Pt(9) footer_run.font.color.rgb = RGBColor(130, 130, 130) # ===================== SAVE ===================== out_path = '/tmp/workspace/digastric-knruhs/Digastric_Muscle_KNRUHS.docx' doc.save(out_path) print(f"Saved: {out_path}") EOF

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Digastric Muscle KNRUHS

Word Document · DOCX

Here's what's included in the document:

Section	Contents
Introduction	Definition, group membership
Attachments	Color-coded table - origin, insertion, embryology for each belly
Nerve Supply ⭐	Highlighted table - mylohyoid n. (V3) vs facial n. (VII), with pharyngeal arch basis
Actions	Hyoid-fixed vs mandible-fixed actions
Triangles ⭐	Submental triangle + Digastric triangle with boundaries & contents
Relations	Important neurovascular crossings of posterior belly
Blood Supply	Submental a. vs post. auricular + occipital aa.
Clinical Anatomy ⭐	Facial nerve palsy, surgical relevance, clinical testing, flap use
Quick Summary Table	All features side-by-side for last-minute review
Mnemonic	"Anterior → Arch 1 → V3

The ⭐ sections are the ones most commonly asked in KNRUHS SAQ pattern - nerve supply with embryological basis, triangles, and clinical applied anatomy.

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