Submandibular salivary gland Larynx Sub occipital region Para nasal sinuses
submandibular gland anatomy relations mylohyoid
Clinical photograph of a gross submandibular gland resection specimen, demonstrating its complex lobular anatomy. The specimen is displayed on a blue surgical drape and is annotated to show the division between the larger superficial lobe and the smaller deep lobe, separated by a dashed line representing the anatomical plane typically defined by the mylohyoid muscle. Extending anteriorly from the deep lobe is the uncinate process, highlighted within a dotted oval. This process appears as an elongated, thinner extension of parenchymal tissue that normally wraps around the posterior border of the mylohyoid muscle to enter the sublingual space. The glandular tissue exhibits a characteristic yellowish-orange, lobulated appearance. This image serves as an educational reference for head and neck surgery, specifically illustrating the 'uncinate process' which can be mistaken for sublingual gland tissue or involved in pathologies like ranulas. The specimen represents an extended resection that includes both the deep lobe and Wharton's duct.
This composite of three clinical photographs (a-c) displays the gross anatomical dissection of the human submental region and mandibular floor. Figure (a) provides a wide superior view showing the mylohyoid muscle (MM), the anterior belly of the digastric muscle (ABDM), the submandibular gland (SMG), and the submandibular lymphatic ganglion (SG). Figures (b) and (c) offer higher magnification views of the right and left sides, respectively, detailing the neurovascular bundle situated between the MM and SMG. The submental nerve (MN), highlighted with yellow arrowheads and dotted lines, is seen coursing alongside the submental artery (SMA, red arrowheads) and the submental vein (SMV, blue arrowheads). These microscopic views emphasize the spatial relationship of the MN as it provides motor innervation to the mylohyoid muscle. The images illustrate the clinical anatomy relevant to submandibular surgery and local anesthesia, specifically identifying fine nerve branches that pierce the mylohyoid muscle to potentially communicate with the lingual nerve.
larynx anatomy cartilages supraglottis glottis subglottis
This diagnostic endoscopic photograph displays the human larynx from a superior view, highlighting the anatomy of the glottis and vocal folds. The primary pathology is a sulcus vocalis, visible as a distinct, linear groove or indentation running longitudinally along the mucosal cover of the right vocal fold (anatomical left of the image), parallel to its free edge. This groove disrupts the normally smooth surface of the vocal fold mucosa. In contrast, the contralateral vocal fold appears more uniform. The surrounding structures include the arytenoid cartilages positioned posteriorly, appearing as rounded pinkish masses, and the epiglottis superiorly. The space between the vocal folds reveals the entrance to the subglottis and trachea. The clinical significance of this finding relates to dysphonia, as the sulcus increases mucosal stiffness and prevents complete glottic closure during phonation. This image serves as an educational reference for Otolaryngology (ENT) residents and medical students studying laryngeal disorders and voice pathology.
This diagnostic endoscopic image, labeled Figure 2(a) and 2(b), displays the laryngeal anatomy under nasopharyngolaryngoscopy. The visual shows significant pathology of the supraglottis, false vocal folds, and interarytenoid region. There is generalized erythema and intense inflammation across the mucosal surfaces. Key clinical findings include multiple scattered petechiae (small, red hemorrhagic spots) on the supraglottic surface and false vocal folds. Darker, focal areas of scabbing or crusting are prominent, particularly within the interarytenoid region and central glottic area. The glottis appears inflamed with associated mucosal edema. These findings are characteristic of laryngeal mucosal injury or hemorrhage. The images provide a clinical example of upper airway irritation or systemic bleeding manifestations within the larynx, relevant for Otolaryngology (ENT) training and diagnostic classification of vocal fold lesions and laryngeal trauma.
suboccipital triangle muscles vertebral artery
This clinical photograph displays a posterior anatomical dissection of the suboccipital region in a human cadaver, highlighting key neurovascular and muscular structures. Labels identify the occiput, vertebral arteries, inferior oblique muscle, semispinalis cervicis, and semispinalis capitis (reflected laterally). Crucially, the image demonstrates a comparative view of the suboccipital nerves (dorsal rami of C1). On the specimen's left side, a significantly enlarged and elongated dorsal ramus of C1 is visible, coursing medially to the vertebral artery as it crosses the posterior arch of the atlas. In contrast, the right-sided C1 nerve exhibits typical morphology. The dorsal rami of the C2 and C3 spinal nerves are also identified bilaterally, positioned inferior to the suboccipital triangle. The dissection illustrates the spatial relationship between the vertebral artery and the suboccipital muscles, specifically showing the artery's proximity to the inferior oblique muscle. This specimen serves as an educational example of anatomical variation in cervical spinal nerve morphology and suboccipital neuroanatomy.
This composite of three anatomical photographs (A-C) illustrates deep neurosurgical triangles of the suboccipital and condylar regions, essential for approaching the jugular foramen (JF). Panel A shows the suboccipital triangle (green), condylar triangle (red), and jugular triangle (yellow), bounded by the superior oblique, inferior oblique, and rectus capitis lateralis (RCL) muscles. Notable vascular structures include the external and internal carotid arteries (ECA, ICA). Panel B highlights the deep condylar and trans-condylar triangles (purple), bounded by the condylar emissary vein (CEV), RCL, and the transverse process of the atlas (TP-C1). The occipital condyle and atlanto-occipital joint (OCJ) are visible after mobilizing the vertebral artery (VA). Panel C demonstrates the supra-hypoglossal (yellow) and infra-hypoglossal (green) triangles after condyle drilling. These triangles serve as surgical corridors to the infrajugular area and OCJ. Key neural landmarks include the facial nerve (CN-7) and hypoglossal nerve (CN-12) near the jugular foramen and the artery of the stylomastoid foramen (aSMF).
paranasal sinuses anatomy diagram frontal maxillary ethmoid sphenoid
This medical anatomical diagram displays the human skull in two views, focusing on the paranasal sinuses and internal cranial structures. View (a) is an anterior (frontal) perspective of the skull with semi-transparent overlays illustrating the paranasal sinuses. Labeled structures include the frontal sinuses located superior to the orbits, the ethmoid sinus situated medially between the eyes, the orbital plate of the ethmoid bone forming the medial orbital wall, the ocular cavity (orbit), and the large maxillary sinuses within the maxilla. View (b) provides a mid-sagittal section of the facial and mid-cranial region. It highlights the spatial relationship between the nasal cavity and surrounding structures, including the frontal sinus, the perpendicular plate of the ethmoid bone (part of the nasal septum), and the maxilla. Posteriorly, it shows the sphenoid bone containing the sella turcica, where the pituitary gland is seated. This illustration is designed for medical education regarding craniofacial anatomy, specifically for procedures such as Functional Endoscopic Sinus Surgery (FESS) and maxillofacial osteotomies.
This historical anatomical diagram by Emil Zuckerkandl (1882) illustrates the paranasal sinuses and nasal anatomy in two planes. Image (a) is a sagittal section of the nasal cavity, detailing the complex arrangement of the superior, middle, and inferior turbinates (conchae) along the lateral wall. It visualizes the frontal sinus superiorly, the sphenoid sinus posteriorly, and the relationship between the nasal cavity and the hard palate. Image (b) presents a frontal (coronal) section, showcasing the bilateral symmetry of the mid-facial anatomy. Key features include the central nasal septum, the convoluted turbinates projecting into the nasal passages, and the expansive maxillary sinuses situated laterally within the maxilla bones. Small ethmoid air cells are visible medially to the orbits and superior to the maxillary sinuses. This anatomical illustration serves as a foundational reference for otorhinolaryngology and neurosurgical approaches, particularly regarding the development of transsphenoidal surgery for pituitary lesions.
1. Submandibular Salivary Gland
Overview
- Size: approximately that of a walnut
- Type: mixed gland, but predominantly serous
- Structure: a larger superficial part and a smaller deep part, continuous around the posterior border of the mylohyoid muscle
- Enclosed within a well-defined capsule derived from the deep cervical fascia (splits to enclose it)
Location
- The superficial part lies in the digastric triangle (submandibular triangle)
- Extends medial to the body of the mandible above; below, it overlaps the intermediate tendon of the digastric muscle and the insertion of the stylohyoid muscle
Relations
| Surface | Relation |
|---|---|
| Inferior surface | Skin, platysma, deep fascia; crossed by the facial vein and cervical branch of facial nerve |
| Lateral surface | Submandibular fossa on medial surface of mandible; medial pterygoid muscle attachment |
| Medial (deep) surface - anterior | Mylohyoid muscle |
| Medial surface - intermediate | Hyoglossus muscle (separated by styloglossus, lingual nerve, submandibular ganglion, hypoglossal nerve, deep lingual vein) |
| Medial surface - posterior | Styloglossus muscle |
| Deep part | Lies between mylohyoid (inferolateral) and hyoglossus/styloglossus (medial); extends forward to posterior end of sublingual gland |
Wharton's Duct (Submandibular Duct)
- Length: approximately 5 cm
- Emerges from the medial surface of the superficial part, behind the posterior border of mylohyoid
- Passes through the deep part of the gland
- Runs between the sublingual gland and genioglossus muscle
- Opens on the summit of the sublingual papilla at the side of the frenulum of the tongue
- On the hyoglossus muscle, it is crossed laterally by the lingual nerve (the lingual nerve winds under the duct)
Blood Supply
- Facial artery: enters deep to the posterior belly of digastric and stylohyoid muscles, passes through or superficial to the gland, then grooves the mandible at its lower border. Glandular branches must be ligated when removing the gland.
- Facial vein: lies superficial to the gland
Nerve Supply
- Secretomotor (parasympathetic):
- Preganglionic fibres travel via the facial nerve → chorda tympani → joins lingual nerve → submandibular ganglion (a small fusiform body on the upper part of hyoglossus, suspended from the lingual nerve)
- Postganglionic fibres from the ganglion are distributed to the submandibular and sublingual glands
- Sympathetic: vasomotor fibres via the plexus on the facial artery
- Marginal mandibular branch of facial nerve: lies in the superficial fascia, traverses over the facial vessels (important in surgery - Martin's technique uses ligation and flipping of these vessels superiorly to protect this nerve during neck dissection)
Calculus (Salivary Stone / Sialolithiasis)
- More common in the submandibular gland than in the parotid (secretion is more viscous/alkaline; duct is longer, tortuous, and ascends against gravity)
- Composition: calcium and magnesium phosphates (similar to dental tartar)
- May form within the gland or its duct
- Pathognomonic feature: swelling of the gland during meals (salivary colic), often preceded by a colicky pain
- Diagnosis: lemon juice test (triggers swelling and reveals absence of salivation from affected duct); bimanual palpation of duct; plain X-ray (80-90% radiopaque); ultrasound
Tumours
- Tumours are uncommon compared to parotid tumours; enlargement is more often due to calculus
- Most common tumour: pleomorphic adenoma (mixed tumour) - slow growing, moderately sized, hard but not stony hard
- Carcinoma: extremely rare
- Mikulicz's disease: symmetrical enlargement of all salivary + lacrimal glands (lymphocytic replacement); dry mouth (xerostomia)
Clinical Note
- Swelling in the submandibular region is more often due to lymph node enlargement than salivary gland tumour
- The hypoglossal nerve must be identified and preserved during gland excision
2. Larynx
Overview
- Location: anterior to the hypopharynx; extends from the tip of the epiglottis (level of lower border of C3) to the lower border of the cricoid cartilage (level of C6)
- Functions: airway protection, phonation, respiration
Cartilaginous Skeleton
Hyaline Cartilages (begin to ossify ~20 years of age - radiopaque)
- Thyroid cartilage: largest; two laminae fused anteriorly forming the laryngeal prominence; vocal cords attach at the "figure-of-eight" on lateral X-ray
- Cricoid cartilage: only complete ring in the airway; narrowest point of the paediatric airway
- Arytenoid cartilages (most of each): paired; sit on the superior surface of the cricoid posteriorly; vocal processes for vocal cord attachment
Elastic Cartilages (do NOT ossify - radiolucent)
- Epiglottis: leaf-shaped; attached to posterior thyroid at its inferior end
- Corniculate cartilages (of Santorini): tips of arytenoids
- Cuneiform cartilages (of Wrisberg): in aryepiglottic folds
- Vocal process and apex of arytenoids
Anatomical Subdivisions
| Region | Boundaries | Structures |
|---|---|---|
| Supraglottis | From tip of epiglottis to lateral wall of ventricle | Suprahyoid + infrahyoid epiglottis, aryepiglottic folds, arytenoids, false vocal cords (ventricular folds), ventricle (of Morgagni) |
| Glottis | True vocal cords + anterior and posterior commissures; lower boundary = 5 mm below free margin of cords (or 1 cm below apex of ventricle) | True vocal cords; anterior commissure (approaches within 1 cm of skin) |
| Subglottis | From lower boundary of glottis to inferior margin of cricoid | Air column; begins transition to trachea |
Key Spaces
- Preepiglottic space: fat-filled space anterior to epiglottis; easily identified on CT/MRI
- Paraglottic (paralaryngeal) space: fat-filled; surrounds the ventricle; important for assessing deep invasion by tumour
- Reinke's space: superficial lamina propria of vocal cord - site of Reinke's oedema (polypoidal degeneration)
Muscles of the Larynx
- Only abductor of vocal cords: Posterior cricoarytenoid (PCA) - opens the airway
- Adductors: Lateral cricoarytenoid, interarytenoid (transverse + oblique)
- Tensors: Cricothyroid (lengthens/tenses cord - extrinsic; supplied by external branch of superior laryngeal nerve)
- Relaxer: Thyroarytenoid (vocalis)
Nerve Supply
- Recurrent laryngeal nerve (RLN) (branch of vagus): supplies all intrinsic muscles EXCEPT cricothyroid; also sensory below vocal cords
- Right RLN: loops around right subclavian artery
- Left RLN: loops around aortic arch (longer course; more vulnerable)
- Superior laryngeal nerve (SLN) (branch of vagus):
- Internal branch: sensory above vocal cords and to epiglottis
- External branch: motor to cricothyroid muscle
Blood Supply
- Superior laryngeal artery (from superior thyroid artery)
- Inferior laryngeal artery (from inferior thyroid artery)
Lymphatic Drainage
- Supraglottic: rich bilateral lymphatics → upper deep cervical nodes (Level II, III)
- Glottic: sparse lymphatics (true cords have almost none - explains low nodal spread in early glottic cancer)
- Subglottic: drains to Level IV and Level VI (pretracheal/paratracheal)
Laryngocele
- Internal type: air sac stays within paralaryngeal fat (supraglottic region)
- External (mixed) type: pierces the thyrohyoid membrane → neck mass
- Cause: increased intraglottic pressure (horn players, glass blowers) or obstruction of laryngeal ventricle
Important Clinical Points
- Epiglottitis (supraglottitis): thickens epiglottis and aryepiglottic folds; "thumbprint sign" on lateral X-ray; life-threatening airway compromise
- Laryngeal fracture on CT: linear lucency in ossified cartilage; best seen on bone windows
- Imaging: CECT and MRI are relatively insensitive to superficial mucosal lesions; fat planes in preepiglottic and paraglottic spaces are key landmarks
3. Suboccipital Region
Overview
- A deep region at the base of the occipital bone in the upper cervical area
- Contains the suboccipital muscles (4 pairs) that move the head at the atlantooccipital and atlantoaxial joints
- All innervated by the suboccipital nerve = posterior ramus of C1 (purely motor)
The Four Suboccipital Muscles
| Muscle | Origin | Insertion | Function |
|---|---|---|---|
| Rectus capitis posterior major | Spinous process of axis (C2) | Lateral part of occipital bone (below inferior nuchal line) | Extension of head; rotation of face to same side |
| Rectus capitis posterior minor | Posterior tubercle of atlas (C1) | Medial part of occipital bone (below inferior nuchal line) | Extension of head |
| Obliquus capitis superior | Transverse process of atlas (C1) | Occipital bone (between superior and inferior nuchal lines) | Extension of head; bends head to same side |
| Obliquus capitis inferior | Spinous process of axis (C2) | Transverse process of atlas (C1) | Rotation of face to same side (largest of the four) |
Suboccipital Triangle
| Border | Muscle |
|---|---|
| Medial | Rectus capitis posterior major |
| Lateral (superior) | Obliquus capitis superior |
| Inferior | Obliquus capitis inferior |
- Posterior ramus of C1 (suboccipital nerve) - emerges above the posterior arch of the atlas between the vertebral artery and the arch
- Vertebral artery - runs through its groove on the superior surface of the posterior arch of the atlas (third part of vertebral artery, V3 segment)
- Suboccipital venous plexus
- Greater occipital nerve (C2) - winds posteriorly as it passes the lower margin of the obliquus capitis inferior → sensory to posterior scalp
- Third occipital nerve (C3) - also passes at this level
Vascular Supply
- Branches of the vertebral artery and occipital artery
- The deep cervical artery (branch of costocervical trunk) runs between semispinalis capitis and cervicis muscles nearby
Overlying Muscles (superficial to suboccipital region, removed during dissection)
- Trapezius
- Sternocleidomastoid
- Splenius capitis
- Semispinalis capitis
Key Landmark
- The spinous process of the axis (C2) is the most important landmark in the deep nuchal region (the largest palpable spinous process in this area)
Clinical Significance
- Suboccipital nerve block / greater occipital nerve block: used in management of cervicogenic headache and occipital neuralgia
- Vertebral artery injury: the V3 segment in the suboccipital triangle is vulnerable during posterior cervical surgery and atlantoaxial surgery
- Suboccipital approach: a neurosurgical/otological approach used to access the posterior cranial fossa and cerebellopontine angle (e.g., for acoustic neuroma)
4. Paranasal Sinuses
Overview
Individual Sinuses
Maxillary Sinus (Antrum of Highmore)
- Largest paranasal sinus
- Located in the body of the maxilla
- Drainage: into the middle meatus via the maxillary ostium → infundibulum (worst drainage - ostium is on the superomedial wall, not the floor)
- Relations: floor = alveolar process (roots of upper molar teeth may project into it); roof = orbital floor; medial wall = lateral nasal wall; posterior wall = infratemporal fossa
- Nerve supply: superior alveolar nerves (branches of maxillary V2)
- First sinus to develop; present at birth as small pouches; adult size by puberty
Frontal Sinus
- Located in the frontal bone, above the orbits
- Drainage: into the middle meatus via the frontonasal duct / nasofrontal recess
- Absent at birth; begins to develop at age 2; reaches adult size by late teens
- Often asymmetric; may be absent unilaterally in 5% of people
- Anterior wall is the thicker; posterior wall is thin (separates from anterior cranial fossa)
Ethmoid Sinuses (Labyrinth)
- Multiple small air cells within the ethmoid bone
- Divided into: anterior ethmoid cells (drain into middle meatus) and posterior ethmoid cells (drain into superior meatus)
- Medial wall: lateral wall of nasal cavity; lateral wall: lamina papyracea (paper-thin - orbital wall; easily breached in trauma or disease)
- Key structure: ethmoid bulla (largest anterior ethmoid cell; landmark for middle meatus)
- Important: most commonly involved in sinusitis, and most commonly implicated in orbital complications of sinusitis
Sphenoid Sinus
- Located in the body of the sphenoid bone
- Drainage: into the sphenoethmoidal recess (above superior turbinate)
- Important relations:
- Superior: pituitary gland in sella turcica, optic chiasm
- Lateral: cavernous sinus (internal carotid artery, oculomotor, trochlear, ophthalmic, abducens nerves)
- Posterior: pons/brainstem
- Inferior floor: nasopharynx
- Surgical importance: transsphenoidal approach to pituitary tumours
The Ostiomeatal Complex (OMC)
- The functional unit of sinus drainage in the middle meatus
- Components: maxillary sinus ostium, infundibulum, uncinate process, ethmoid bulla, hiatus semilunaris, middle turbinate
- Uncinate process forms the medial wall of the infundibulum; ethmoid bulla forms the lateral wall
- Haller cells (infraorbital ethmoid cells): anatomic variant that can narrow the infundibulum → predisposes to sinusitis
- Obstruction of the OMC → impaired mucociliary clearance → sinusitis
Drainage Summary
| Sinus | Drains Into |
|---|---|
| Maxillary | Middle meatus (via hiatus semilunaris) |
| Frontal | Middle meatus (via frontonasal duct) |
| Anterior ethmoid | Middle meatus |
| Posterior ethmoid | Superior meatus |
| Sphenoid | Sphenoethmoidal recess |
Imaging
- CT (NCCT): investigation of choice for sinuses; essential for pre-operative planning before FESS (Functional Endoscopic Sinus Surgery)
- Coronal plane: best for OMC anatomy and preoperative planning
- CT distinguishes: aerated sinus (normal), mucosal thickening (chronic sinusitis), air-fluid level (acute sinusitis), complete opacification (mucocele, tumour)
- MRI: superior for distinguishing tumour from obstructed secretions; sinusonasal tumours show low-to-intermediate signal on T2WI; obstructed inspissated mucus shows high T1 and variable T2
Pathological Conditions
- Sinusitis: Acute (air-fluid level), Chronic (mucosal thickening + bony sclerosis), Invasive (mucormycosis - destroys bone rapidly; in immunocompromised)
- Mucocele: complete obstruction → slow expansion; remodels bone (not destroys it); most common in frontal sinus
- Nasal polyps: eosinophilic; "cascading" enhancement pattern on CECT; arise from ethmoid mucosa
- Malignancy: bone destruction on CT; low-to-intermediate T2 signal on MRI; adenoid cystic carcinoma and squamous cell carcinoma are most common
Quick Reference Summary
| Topic | Key Numbers/Facts |
|---|---|
| Submandibular gland | Wharton's duct = 5 cm; opens at sublingual papilla; lingual nerve crosses over duct |
| Larynx | C3 (epiglottis tip) to C6 (cricoid lower border); only abductor = PCA; only intrinsic muscle with SLN = cricothyroid |
| Suboccipital triangle | Medial = rectus capitis major; lateral = obliquus superior; inferior = obliquus inferior; contents = C1 ramus, vertebral artery, veins |
| Paranasal sinuses | Posterior ethmoid + sphenoid DO NOT drain into middle meatus; OMC = key functional unit; lamina papyracea = orbital wall of ethmoid |