| Structure/Space | Description/Boundaries | Significance |
|---|---|---|
| carotid triangle | boundaries: anterior - superior belly of the omohyoid m.; posterior - sternocleidomastoid m.; superior - posterior belly of the digastric m.; | the carotid artery branches here |
| cervical triangle, anterior | boundaries: medial - midline; lateral - anterior border of the sternocleidomastoid m.; superior - lower border of the mandible | anterior cervical triangle may be subdivided into the carotid triangle and the muscular triangle |
| cervical triangle, posterior | boundaries: anterior - sternocleidomastoid m.; posterior - trapezius m.; inferior - middle 1/3 of the clavicle | posterior cervical triangle may be subdivided by the inferior belly of the omohyoid m. to form an omoclavicular triangle; the external jugular vein crosses the posterior cervical triangle |
| cranial fossa, anterior | boundaries: anterior - inner surface of the frontal bone; posterior - posterior edge of the lesser wing of the sphenoid bone | frontal lobes of the brain are located within the anterior cranial fossa; cranial nerve I exits the cranial cavity here |
| cranial fossa, middle | boundaries: anterior - posterior edge of the lesser wing of the sphenoid bone; posterior - petrous ridge of the temporal bone | temporal lobes of the brain and pituitary gland are located within the middle cranial fossa; cranial nerves II, III, IV, V and VI exit the cranial cavity here |
| cranial fossa, posterior | boundaries: anterior - petrous ridge of the temporal bone; posterior - inner surface of the occipital bone | cerebellum and brainstem are located within the posterior cranial fossa; cranial nerves VII, VIII, IX, X, XI and XII exit the cranial cavity here |
| infratemporal fossa | area medial to the angle of the mandible bounded above by the infratemporal surface of the greater wing of the sphenoid bone, anteriorly by the alveolar border of the maxilla, laterally by the ramus of the mandible and deeply by the lateral pterygoid plate of the sphenoid bone | infratemporal fossa has the foramen rotundum and foramen spinosum in its roof; maxillary a. and its branches are located here; branches of the mandibular division of the trigeminal nerve (V3) are located here |
| muscular triangle | boundaries: medial - midline; superior - body of the hyoid bone; superolateral - superior belly of the omohyoid m.; inferolateral - sternocleidomastoid m. | muscular triangle contains the strap muscles of the neck; larynx and thyroid gland lie deep to the strap muscles |
| omoclavicular triangle | boundaries: superior - inferior belly of the omohyoid m.; anterior - sternocleidomastoid m.; inferior - middle 1/3 of the clavicle | the external jugular vein courses deeply through the omoclavicular triangle |
| submandibular triangle | boundaries: anterior - anterior belly of the digastric m.; posterior - posterior belly of the digastric m.; superior - lower border of mandible | submandibular triangle contains the submandibular gland |
| submental triangle | boundaries: lateral - anterior belly of the digastric m.; medial - midline; inferior - body of the hyoid bone | submental triangle contains the submental a. and v. |
| temporal fossa | area on the lateral surface of the skull bounded above by the temporal lines, anteriorly by the frontal and zygomatic bones and inferiorly by the zygomatic arch; it is bounded deeply by the frontal, parietal and temporal bones and the greater wing of the sphenoid bone | the temporalis m. nearly fills the temporal fossa |