make a chart of pelvic floor muscles including muscle, origin, insertion, action, innervation and group
I'll look up the pelvic floor muscles from the medical library for accurate anatomical detail.
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Finding Sources
Excellent - found dedicated tables in Gray's Anatomy for Students and Berek & Novak's Gynecology. Let me read both simultaneously.
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I need more content from the THIEME Atlas table and the Berek & Novak table for the perineal/urogenital muscles. Let me read more.
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I also need to get the Iliococcygeus insertion which was cut off. Let me also grab Berek & Novak's table and the THIEME bulbospongiosus data.
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I now have comprehensive data from three authoritative textbooks. I also note the THIEME Atlas has the Coccygeus origin/insertion reversed from other sources (ischial spine = origin, sacrum = insertion is the correct anatomy). Let me compile the full chart now.
Pelvic Floor Muscles: Complete Anatomical Chart
Sources: Gray's Anatomy for Students (Table 5.2), THIEME Atlas of Anatomy: General Anatomy and Musculoskeletal System (Section 2.10), Berek & Novak's Gynecology (Table 5-2), Campbell-Walsh-Wein Urology
Group I - Pelvic Diaphragm
| Muscle | Origin | Insertion | Action | Innervation | Group |
|---|---|---|---|---|---|
| Levator ani (overall) | Tendinous arch (thickening of obturator internus fascia), posterior body of pubis to ischial spine | Perineal body, wall of anal canal, anococcygeal ligament, coccyx (varies by part) | Supports pelvic viscera; maintains anorectal angle; reinforces external anal sphincter; acts as vaginal sphincter in females | Branches from anterior ramus of S4; inferior rectal branch of pudendal nerve (S2-S4) | Pelvic Diaphragm |
| - Puborectalis | Superior pubic ramus, both sides of pubic symphysis | Loops around anorectal junction; interwoven with deep external anal sphincter (U-shaped sling) | Maintains anorectal angle; aids fecal continence | Pudendal nerve and direct branches of sacral plexus (S2-S4) | Pelvic Diaphragm (Levator ani) |
| - Pubococcygeus | Posterior portion of pubis and tendinous arch (lateral to puborectalis origin) | Anococcygeal ligament, coccyx; forms pubovaginal sling around vagina/urethra | Supports pelvic viscera; visceral control via pubovaginal sling around vagina and urethra | Pudendal nerve (S2-S4) | Pelvic Diaphragm (Levator ani) |
| - Iliococcygeus | Tendinous arch of obturator internus fascia (posterior part) and ischial spine | Iliococcygeal raphe, anococcygeal ligament, coccyx | Supports pelvic viscera; holds pelvic organs in place | Pudendal nerve (S2-S4) | Pelvic Diaphragm (Levator ani) |
| Coccygeus | Ischial spine and pelvic surface of the sacrospinous ligament | Lateral margin of coccyx and lower sacrum (S4-S5) | Supports pelvic floor; flexes/pulls coccyx anteriorly after defecation | Branches from anterior rami of S3-S5 (direct sacral plexus branches) | Pelvic Diaphragm |
Group II - Urogenital Diaphragm (Deep Perineal Pouch)
| Muscle | Origin | Insertion | Action | Innervation | Group |
|---|---|---|---|---|---|
| Deep transverse perineal | Medial aspect of ischiopubic rami / inferior pubic ramus | Lower vaginal wall; anterior fibers blend with external urethral sphincter; blends at perineal body | Stabilizes perineal body; supports urogenital structures; closes urethra | Pudendal nerve (S2-S4) | Urogenital Diaphragm |
| External urethral sphincter | Inferior pubic ramus (outer striated part = omega-shaped; inner ring = smooth muscle) | Encircles urethra | Closes and controls the urethra (voluntary) | Pudendal nerve (S2-S4) | Urogenital Diaphragm |
Group III - Superficial Perineal Muscles
| Muscle | Origin | Insertion | Action | Innervation | Group |
|---|---|---|---|---|---|
| Superficial transverse perineal | Ischial ramus (ischial tuberosity) | Perineal body (central perineal tendon) | Stabilizes perineal body; holds pelvic organs in place | Pudendal nerve (S2-S4) | Superficial Perineal |
| Bulbospongiosus | Perineal body (anteriorly to clitoris in females; to penile raphe in males) | Clitoris/dorsal surface (females); corpus spongiosum (males) | Narrows vaginal introitus (females); compresses corpus spongiosum (males); aids erection/ejaculation | Pudendal nerve (S2-S4) | Superficial Perineal |
| Ischiocavernosus | Ischial ramus | Crus of penis or clitoris | Compresses crura; maintains erection by impeding venous outflow | Pudendal nerve (S2-S4) | Superficial Perineal |
| External anal sphincter | Perineal body (anteriorly), encircles anal canal to anococcygeal ligament (posteriorly) | Circular around anal canal; divided into subcutaneous, superficial, and deep parts | Closes the anus (voluntary continence) | Pudendal nerve (S2-S4); inferior rectal nerve | Superficial Perineal |
Group IV - Lateral Pelvic Wall Muscles (contribute to pelvic support)
| Muscle | Origin | Insertion | Action | Innervation | Group |
|---|---|---|---|---|---|
| Obturator internus | Superior and inferior pubic rami; obturator membrane | Greater trochanter of the femur | Lateral rotation of thigh; assists in stabilizing femoral head; forms lateral pelvic wall | Obturator internus nerve (L5-S1) | Lateral Pelvic Wall |
| Piriformis | Anterior aspect of S2-S4 sacral segments; sacrotuberous ligament | Greater trochanter of the femur | Lateral rotation and abduction of thigh in flexion; holds femoral head in acetabulum; forms muscular bed for sacral plexus | S1-S2 (direct sacral plexus branches) | Lateral Pelvic Wall |
Key Points
- All pelvic diaphragm and perineal muscles are innervated by the pudendal nerve (S2-S4), with the coccygeus receiving additional direct sacral plexus input (S3-S5).
- The levator ani nerve (from S3-S4-S5, traveling medial to the ischial spine) is now recognized as the primary innervation to the levator ani complex - distinct from the pudendal nerve which innervates it from below.
- The perineal body (central perineal tendon) is the keystone structure where bulbospongiosus, superficial/deep transverse perineal, and external anal sphincter converge.
- The tendinous arch of the levator ani (ATLA) is the fascial condensation over obturator internus from which puborectalis, pubococcygeus, and iliococcygeus originate.
Same for the shoulder muscles
Finding Sources
Finding Sources
Good - THIEME Atlas has dedicated sections for both shoulder girdle and shoulder joint muscles. Let me read all relevant sections in parallel.
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This is the table of contents - the detailed data must be in another block. Let me search for the actual muscle tables with origin/insertion data.
Finding Sources
Finding Sources
Excellent - found great tables in Gray's Anatomy for Students (block1 and block4) and Miller's Review of Orthopaedics. Let me read all three simultaneously.
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I have excellent data. Let me read more of the Gray's block4 table to get the rotator cuff and remaining shoulder muscles.
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I have all the core data I need. Let me also quickly get the rotator cuff + pectoralis/serratus details from Gray's block4 table which was partially cut off.
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I have all the data I need. Let me now compile the full comprehensive chart. The key table from Gray's block4 (Table 7.1) had the first group; I need to confirm that table also had the rotator cuff muscles. Let me check the block1 table which had more complete content.
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I now have all the information needed from multiple authoritative sources. Let me compile the complete chart.
Shoulder Muscles: Complete Anatomical Chart
Sources: Gray's Anatomy for Students (Tables 2.1 & 7.1), Miller's Review of Orthopaedics, Campbell's Operative Orthopaedics
Group I - Shoulder Girdle Muscles (Posterior / Superficial Back)
| Muscle | Origin | Insertion | Action | Innervation | Group |
|---|---|---|---|---|---|
| Trapezius | Superior nuchal line, external occipital protuberance, ligamentum nuchae, spinous processes of C7-T12 | Lateral 1/3 of clavicle (posterior border), acromion, spine of scapula | Upper fibers: elevate scapula; middle fibers: retract scapula; lower fibers: depress scapula; upper + lower together: rotate scapula for arm abduction above horizontal | Motor - Accessory nerve (CN XI); Proprioception - anterior rami C3, C4 | Shoulder Girdle (Superficial Back) |
| Levator scapulae | Transverse processes of C1-C4 (posterior tubercles of C3-C4) | Posterior surface of medial border of scapula, superior angle to root of spine | Elevates scapula; assists in rotating lateral scapula inferiorly | Dorsal scapular nerve (C5); direct branches from anterior rami C3, C4 | Shoulder Girdle (Superficial Back) |
| Rhomboid minor | Lower ligamentum nuchae; spinous processes of C7-T1 | Posterior surface of medial border of scapula at root of spine | Retracts and elevates scapula; rotates glenoid cavity inferiorly | Dorsal scapular nerve (C5) | Shoulder Girdle (Superficial Back) |
| Rhomboid major | Spinous processes of T2-T5 and supraspinous ligaments | Posterior surface of medial border of scapula from root of spine to inferior angle | Retracts and elevates scapula; rotates glenoid cavity inferiorly | Dorsal scapular nerve (C4, C5) | Shoulder Girdle (Superficial Back) |
| Latissimus dorsi | Spinous processes of T7-L5 and sacrum, iliac crest, ribs 10-12 | Floor of intertubercular sulcus (bicipital groove) of humerus | Extends, adducts, and medially rotates humerus; depresses shoulder | Thoracodorsal nerve (C6, C7, C8) | Shoulder Girdle (Superficial Back) |
Group II - Shoulder Girdle Muscles (Anterior / Chest)
| Muscle | Origin | Insertion | Action | Innervation | Group |
|---|---|---|---|---|---|
| Pectoralis major | Sternal half of clavicle; anterior sternum; costal cartilages of ribs 1-6; aponeurosis of external oblique | Lateral lip of intertubercular sulcus (bicipital groove) of humerus | Adducts and medially rotates humerus; clavicular head: flexes arm; sternocostal head: extends arm from flexed position | Medial pectoral nerve (C8, T1); lateral pectoral nerve (C5, C6, C7) | Shoulder Girdle (Anterior) |
| Pectoralis minor | Outer surfaces of ribs 3-5 (near costal cartilages) | Coracoid process of scapula | Protracts (tilts anteriorly) and depresses scapula; elevates ribs in forced inspiration | Medial pectoral nerve (C8, T1) | Shoulder Girdle (Anterior) |
| Serratus anterior | Outer surfaces of ribs 1-9 (digitations) | Costal (anterior/deep) surface of medial border of scapula | Protracts scapula; holds scapula against thoracic wall; rotates glenoid cavity superiorly; prevents winging | Long thoracic nerve (C5, C6, C7) | Shoulder Girdle (Anterior) |
| Subclavius | Rib 1 (junction of rib and costal cartilage) | Inferior surface of middle third of clavicle | Depresses and stabilizes clavicle; protects sternoclavicular joint | Nerve to subclavius (C5, C6) - upper trunk | Shoulder Girdle (Anterior) |
Group III - Rotator Cuff Muscles (SITS)
| Muscle | Origin | Insertion | Action | Innervation | Group |
|---|---|---|---|---|---|
| Supraspinatus | Supraspinous fossa of scapula | Superior facet of greater tubercle of humerus | Initiates and assists deltoid in arm abduction (0-15°); stabilizes glenohumeral joint | Suprascapular nerve (C4, C5, C6) | Rotator Cuff |
| Infraspinatus | Infraspinous fossa of scapula | Middle facet of greater tubercle of humerus | Laterally (externally) rotates humerus; stabilizes glenohumeral joint | Suprascapular nerve (C5, C6) | Rotator Cuff |
| Teres minor | Lateral border / upper two-thirds of posterior surface of scapula (below infraglenoid tubercle) | Inferior facet of greater tubercle of humerus | Laterally (externally) rotates humerus; weakly adducts arm; stabilizes glenohumeral joint | Axillary nerve (C5, C6) | Rotator Cuff |
| Subscapularis | Subscapular fossa (costal/anterior surface of scapula) | Lesser tubercle of humerus | Medially (internally) rotates humerus; adducts arm; provides anterior stability to glenohumeral joint | Upper and lower subscapular nerves (C5, C6, C7) | Rotator Cuff |
Group IV - Deltoid Region / Shoulder Joint Muscles (Non-Cuff)
| Muscle | Origin | Insertion | Action | Innervation | Group |
|---|---|---|---|---|---|
| Deltoid | Inferior edge of spine of scapula, lateral acromion, anterior border of lateral 1/3 of clavicle | Deltoid tuberosity of humerus (lateral shaft) | Major abductor of arm (middle fibers); anterior fibers: flex and medially rotate; posterior fibers: extend and laterally rotate | Axillary nerve (C5, C6) | Shoulder Joint |
| Teres major | Oval area on posterior surface of inferior angle of scapula | Medial lip of intertubercular sulcus of humerus | Extends, adducts, and medially rotates humerus ("lat's little helper") | Lower subscapular nerve (C5, C6, C7) | Shoulder Joint |
| Coracobrachialis | Tip of coracoid process of scapula | Middle of medial surface of humeral shaft | Flexes and adducts arm at shoulder | Musculocutaneous nerve (C5, C6, C7) | Shoulder Joint |
Key Points
- The rotator cuff (SITS) - Supraspinatus, Infraspinatus, Teres minor, Subscapularis - forms a musculotendinous sleeve around the glenohumeral joint, providing dynamic stability. The cuff compresses the humeral head into the glenoid during all shoulder movements.
- Axillary nerve (C5-C6) innervates both the deltoid and teres minor. It wraps around the surgical neck of the humerus and is vulnerable in proximal humeral fractures and anterior shoulder dislocations.
- The "winging" test: Loss of the long thoracic nerve (C5-C7) paralyzes serratus anterior and causes medial winging of the scapula. Loss of the spinal accessory nerve (CN XI) paralyzes trapezius and causes lateral winging.
- Suprascapular nerve (C4-C6) passes through the suprascapular notch (below the superior transverse scapular ligament) to supply supraspinatus, then curves around the spinoglenoid notch to supply infraspinatus.
- Teres major is NOT part of the rotator cuff despite its proximity - it inserts on the medial lip (not greater/lesser tubercle) and does not blend into the joint capsule.
- Dorsal scapular nerve (C5) supplies both rhomboids and contributes to levator scapulae, running alongside the medial border of the scapula.
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