Mandible Muscle attach Nerve supply of muscle Ossification Condyle a ki lage-joint Facial musscle with nerve supply Tonsil microscopic feature arterial supply Laryngx r part.. Epithelium Nerver supply Kno recurrent nerve bole. Koi theke ata back kore Axis vertebra as usal ja ja dhore Tongue r nerve suppply extrinsic muscle ~Prohelika mam(aro onek ace individual sobai dia dis)
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📚 Anatomy Revision Notes - Prohelika Mam's Topics
1. MANDIBLE
Parts
- Body - divided into base (lower) and alveolar part (upper, bears teeth)
- Ramus - two, quadrangular shaped, one on each side
- Angle of mandible - where body meets ramus
Important Landmarks
- Mental foramen - on body, midway between alveolar and lower borders; transmits mental nerve & vessels
- Mental protuberance + mental tubercles - midline swelling anteriorly
- Mandibular foramen - on medial surface of ramus; transmits inferior alveolar nerve & vessels
- Mylohyoid line - runs posterosuperiorly on inner surface of body
- Lingula - small bony spine guarding mandibular foramen
- Superior & Inferior mental spines (genial spines) - behind mandibular symphysis on inner surface; attachment for genioglossus (upper) and geniohyoid (lower)
- Oblique line - external surface; attachment for depressors of lower lip
- Retromolar triangle - just behind last molar tooth
- Pterygomandibular raphe - attaches to retromolar triangle
Muscle Attachments on Mandible
| Attachment Site | Muscle(s) |
|---|---|
| Superior genial spine | Genioglossus |
| Inferior genial spine | Geniohyoid |
| Mylohyoid line | Mylohyoid |
| Sublingual fossa (above mylohyoid line - anterior 1/3) | Sublingual gland lies here |
| Submandibular fossa (below mylohyoid line - posterior 2/3) | Submandibular gland lies here |
| Alveolar part of body + pterygomandibular raphe | Buccinator |
| Oblique line | Depressor labii inferioris, Depressor anguli oris |
| Coronoid process | Temporalis |
| Medial surface of ramus | Medial pterygoid |
| External surface of ramus + angle | Masseter |
| Mandibular foramen area | Inferior alveolar nerve & vessels enter here |
Nerve Supply of Mandibular Muscles (Muscles of Mastication)
All muscles of mastication (Masseter, Temporalis, Medial and Lateral Pterygoid) are supplied by CN V3 - Mandibular division of Trigeminal nerve
- Masseter - Masseteric nerve (V3)
- Temporalis - Deep temporal nerves (V3)
- Medial pterygoid - Medial pterygoid nerve (V3)
- Lateral pterygoid - Lateral pterygoid nerve (V3)
- Mylohyoid + Anterior belly of digastric - Mylohyoid nerve (branch of inferior alveolar, from V3)
Ossification of Mandible
- Membrane bone - ossifies in intramembranous (desmal) ossification
- 1 primary centre of ossification on each side (near mental foramen, in membrane lateral to Meckel's cartilage)
- Appears at 6th week IU (intra-uterine)
- Meckel's cartilage disappears but its posterior part forms:
- Malleus (head + neck)
- Incus (short process + body)
- Anterior malleolar ligament
- Sphenomandibular ligament
- Condylar cartilage - secondary cartilage - contributes to condyle (forms endochondrally); appears around 10th week IU
- Coronoid cartilage - secondary, appears and disappears
- Mandibular symphysis - fuses by end of 1st year of life
- (Source: Gray's Anatomy for Students)
Mandible Condyle - Cartilage & Joint
Condylar cartilage:
- The condyle of the mandible is covered by fibrocartilage (NOT hyaline cartilage - this is a key distinction from other synovial joints)
Temporomandibular Joint (TMJ):
- Type: Synovial, condyloid (modified hinge)
- Articular surfaces: Head (condyle) of mandible + Mandibular fossa + articular tubercle of temporal bone
- Articular disc (meniscus) divides the joint into upper and lower compartments
- Upper: Gliding movement (translation)
- Lower: Hinge movement (rotation)
- Articular surfaces are covered by fibrocartilage (exception - most synovial joints use hyaline)
- Capsule reinforced by lateral (temporomandibular) ligament
- Accessory ligaments: Sphenomandibular, Stylomandibular
Movements & Muscles:
- Depression: Lateral pterygoid + gravity (digastric, mylohyoid, geniohyoid assist)
- Elevation: Masseter + Medial pterygoid + Temporalis
- Protraction: Lateral pterygoid + Medial pterygoid
- Retraction: Posterior temporalis + deep masseter
- Side-to-side: Pterygoids of opposite side
2. FACIAL MUSCLES WITH NERVE SUPPLY
All muscles of facial expression are supplied by CN VII (Facial Nerve)
| Muscle | Action |
|---|---|
| Frontalis | Raises eyebrows (surprise), wrinkles forehead |
| Orbicularis oculi | Closes eye (blinking, winking, forced closure) |
| Corrugator supercilii | Draws eyebrows medially - frowning |
| Procerus | Draws medial brow down, wrinkles nose bridge |
| Nasalis | Compresses/dilates nostril |
| Orbicularis oris | Closes/purses lips |
| Buccinator | Compresses cheek (blowing, sucking, chewing) - nerve: Buccal branch CN VII |
| Zygomaticus major | Pulls angle of mouth up & laterally - smiling |
| Zygomaticus minor | Elevates upper lip |
| Levator labii superioris | Elevates upper lip |
| Levator labii superioris alaeque nasi | Elevates lip & ala nasi |
| Depressor labii inferioris | Depresses lower lip |
| Depressor anguli oris | Depresses angle of mouth |
| Mentalis | Everts lower lip |
| Risorius | Pulls angle of mouth laterally |
| Platysma | Depresses mandible + lower lip |
| Auricularis (anterior, superior, posterior) | Moves auricle |
Nerve supply branches of CN VII at parotid:
- Temporal
- Zygomatic
- Buccal
- Marginal mandibular
- Cervical
Memory: "To Zanzibar By Motor Car"
3. TONSIL - MICROSCOPIC FEATURES & ARTERIAL SUPPLY
Waldeyer's Ring (Lymphoid ring at pharyngeal entrance)
- Palatine tonsils (paired, lateral)
- Pharyngeal tonsil / Adenoids (posterior, superior)
- Lingual tonsil (base of tongue)
- Tubal tonsils (around eustachian tube openings)
Microscopic Features (Palatine Tonsil - Histology)
(From: Histology - A Text and Atlas, Ross & Pawlina)
- Epithelium: Stratified squamous epithelium covers the free (medial) surface
- Tonsillar crypts (10-15 in number): Epithelium dips deep into connective tissue forming blind-ending, branching crypts extending through whole thickness of tonsil
- Lymphatic nodules: Numerous nodules in the mucosa; nodules have germinal centers (GCs) - appear eosinophilic on H&E
- Lymphocytic infiltration: Lymphocytes infiltrate the crypt epithelium to such an extent that the epithelial-connective tissue border is obliterated
- Hemicapsule (fibrous capsule): Covers deep (lateral) aspect; separates from superior constrictor muscle
- Submucosa: Dense connective tissue beneath nodules
- NO afferent lymphatics (like all lymphoid tissue - except lymph nodes); only efferent lymphatics are present
- Mucous glands (MG) at base of crypts
Key H&E staining pattern:
- Dark (basophilic) areas = lymphoid tissue (lymphocytes)
- Germinal centers = lighter (eosinophilic) areas within nodules
Arterial Supply of Palatine Tonsil
5 arteries supply the tonsil (mnemonic: "Don't Forget Lightly Pressing Areas"):
- Dorsal lingual artery (branch of lingual artery) - lower pole
- Facial artery (tonsillar branch) - main supply, upper pole
- Lesser palatine artery (from maxillary via descending palatine) - upper pole
- Paratonsillar/Ascending palatine artery (branch of facial)
- Ascending pharyngeal artery (from external carotid) - posterior
External palatine (paratonsillar) vein - descends from soft palate lateral to hemicapsule - important surgical landmark; bleeding from this vein complicates tonsillectomy
(Source: Scott-Brown's Otorhinolaryngology; Histology Atlas - Ross & Pawlina)
4. LARYNX
Parts / Cartilages
(Source: Gray's Anatomy for Students)
3 Unpaired cartilages:
- Cricoid - most inferior, signet ring shaped (broad lamina posteriorly, narrow arch anteriorly); only cartilage forming complete ring around airway
- Thyroid - largest, formed by two laminae; angle 90° in males, 120° in females; Adam's apple = laryngeal prominence
- Epiglottis - leaf-shaped, posterior to tongue
3 Paired cartilages:
4. Arytenoid (paired) - pyramid-shaped, sit on superior lamina of cricoid; has vocal process and muscular process
5. Corniculate (paired) - small, sit atop arytenoids
6. Cuneiform (paired) - small, in aryepiglottic fold
Laryngeal Cavity - 3 Regions
| Region | Location | Folds |
|---|---|---|
| Vestibule (supraglottic) | Above vestibular folds | - |
| Middle chamber (glottis) | Between vestibular & vocal folds | Laryngeal ventricles on each side |
| Infraglottic cavity | Below vocal folds to trachea | - |
- Rima glottidis = opening between vocal folds
- Rima vestibuli = opening between vestibular folds
- Laryngeal ventricle = lateral recess between vestibular and vocal folds
- Laryngeal saccule = anterosuperior extension of ventricle; mucous glands here lubricate vocal folds
Epithelium of Larynx
- Epiglottis (anterior surface & upper half posterior): Stratified squamous epithelium
- True vocal cords (vocal folds): Stratified squamous epithelium (non-keratinized)
- Rest of larynx (vestibule, infraglottis, ventricles): Pseudostratified ciliated columnar (respiratory epithelium)
- The junction between stratified squamous and respiratory epithelium occurs at the vocal folds
Nerve Supply of Larynx
All from Vagus nerve (CN X) via two branches:
| Nerve | Type | Area Supplied |
|---|---|---|
| Internal laryngeal nerve (branch of superior laryngeal nerve) | Sensory only | Mucosa above vocal folds (supraglottic) |
| External laryngeal nerve (branch of superior laryngeal nerve) | Motor only | Cricothyroid muscle |
| Recurrent laryngeal nerve (RLN) | Motor + Sensory | All intrinsic muscles EXCEPT cricothyroid; Sensory below vocal folds |
Intrinsic Muscles & Their Actions
| Muscle | Action | Nerve |
|---|---|---|
| Posterior crico-arytenoid (PCA) | Abducts vocal folds (opens rima) - ONLY abductor | RLN |
| Lateral crico-arytenoid (LCA) | Adducts vocal folds | RLN |
| Transverse arytenoid | Adducts arytenoids | RLN |
| Oblique arytenoid | Narrows laryngeal inlet | RLN |
| Vocalis | Tenses vocal fold | RLN |
| Cricothyroid | Tenses/elongates vocal folds (raises pitch) | External laryngeal nerve |
Recurrent Laryngeal Nerve (RLN) - Course
Origin: Branch of Vagus nerve (CN X)
Right RLN:
- Branches from right vagus at the root of neck
- Loops under the right subclavian artery
- Ascends in the tracheo-oesophageal groove
- Enters larynx posterior to cricothyroid joint
Left RLN:
- Branches from left vagus in the thorax (lower path)
- Loops under the arch of aorta (specifically under the ligamentum arteriosum, lateral to ligamentum)
- Ascends in the tracheo-oesophageal groove on the left
- Enters larynx posterior to cricothyroid joint
Clinical: Why is the left RLN more vulnerable?
- Longer course (through thorax, loops under aortic arch)
- Susceptible to: aortic aneurysm, mediastinal masses, lung (left upper lobe) tumors, left-sided thyroid/parathyroid surgery
Injury to RLN:
- Unilateral: Hoarseness (weak/breathy voice)
- Bilateral: Airway obstruction (both vocal folds may adduct - emergency)
5. AXIS VERTEBRA (C2) - Important Features
(Source: Gray's Anatomy for Students)
Key Features
- Dens (odontoid process) - tooth-like projection extending superiorly from vertebral body; the key feature distinguishing axis from other vertebrae
- Anterior facet on dens - articulates with posterior surface of anterior arch of atlas (C1)
- Circular impressions (superolateral surfaces of dens) - attachment of alar ligaments (connect dens to occipital condyles; check excessive rotation)
- Transverse ligament of atlas - holds dens posteriorly against anterior arch of atlas
- Superior articular facets - on superolateral surfaces; articulate with inferior facets of atlas
- Inferior articular facets - on body/arch; articulate with C3
- Vertebral foramen - triangular/large
- Bifid spinous process (like other C vertebrae)
- Transverse foramina - for vertebral artery (C1-C6)
Joints of Axis
- Atlanto-axial joint (C1-C2): Pivot joint; dens acts as pivot; allows rotation of head side-to-side (~50% of rotation occurs here)
- Median atlanto-axial joint (dens + anterior arch of atlas)
- Lateral atlanto-axial joints (bilateral)
Ossification of Axis
- Body: 1 primary centre
- Dens: 2 primary centres (fuse with each other first, then fuse with body by age 3-6 years)
- Neural arches: 1 centre each side
- Apical ossification centre of dens (summit ossicle) - appears at 3-5 years, fuses by 12 years
6. TONGUE - NERVE SUPPLY & EXTRINSIC MUSCLES
Extrinsic Muscles of Tongue (4 pairs)
| Muscle | Origin | Insertion | Action | Nerve |
|---|---|---|---|---|
| Genioglossus | Superior/inferior mental spines of mandible | Lateral & inferior tongue + hyoid | Depresses & protrudes tongue (main muscle) | Hypoglossal (CN XII) |
| Hyoglossus | Body & greater horn of hyoid | Lateral & inferior tongue | Depresses & retracts tongue | Hypoglossal (CN XII) |
| Styloglossus | Styloid process (temporal bone) | Side of tongue blending with hyoglossus | Retracts & elevates tongue | Hypoglossal (CN XII) |
| Palatoglossus | Palatine aponeurosis | Side of tongue | Elevates tongue + narrows oropharyngeal isthmus | Pharyngeal plexus (CN X + CN XI) |
Important exam point: Palatoglossus is the ONLY tongue muscle NOT supplied by hypoglossal nerve - supplied by pharyngeal plexus (vagus + accessory).
Intrinsic Muscles (all CN XII)
| Muscle | Action |
|---|---|
| Superior longitudinal | Elevates tip; shortens tongue |
| Inferior longitudinal | Curls tip inferiorly; shortens tongue |
| Transverse | Narrows & lengthens tongue |
| Vertical | Flattens & broadens tongue |
Nerve Supply - Complete Summary
| Nerve | Area | Function |
|---|---|---|
| Lingual nerve (V3 branch) | Anterior 2/3 | General sensation (touch, pain, temp) |
| Chorda tympani (via lingual nerve, from VII) | Anterior 2/3 | Taste |
| Glossopharyngeal (CN IX) | Posterior 1/3 | General sensation + Taste |
| Internal laryngeal nerve (CN X) | Posterior most (epiglottis area, valleculae) | Sensation |
| Hypoglossal (CN XII) | ALL tongue muscles (except palatoglossus) | Motor |
Prepared from: Gray's Anatomy for Students; Scott-Brown's Otorhinolaryngology Head & Neck Surgery; Histology - A Text and Atlas (Ross & Pawlina); Cummings Otolaryngology Head & Neck Surgery
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