Plan of the neck Flashcards
What are the important surface landmarks of the neck?
- Upper limit
1) The inferior border of the mandible
2) The mastoid process of the temporal bone
3) The external occipital protuberance
- Inferiorly
1) The upper border of the manubri sterni
2) Clavicle
What is the hyoid bone?
- U-shaped bone, with a body, lesser and greater cornu (horns), it is the first resistant structure that can be felt in the midline inferior to the chin
- It is leveled with the C3 vertebrae
- It moves during swallowing
- Suspended from the styloid process via the stylohyoid ligaments
- Muscles (supra & infrahyoid) connects the hyoid bone to the tounge, mandible, sternum, larynx and pharynx
- A fracture to it will cause problems in breathing, swallowing, and speaking
Describe the laryngeal prominence
- Formed by the thyroid cartilage
- More prominent in males and it rises with swallowing
- It lies at the level of the C4 & C5 Vertebrae
- Below it is the cricoid cartilage located at C6
What is the vertebral relation of the hyoid bone?
C3
What is the vertebral relation of the thyroid cartilage?
C4 and C5
What is the vertebral relation of the cricoid cartilage?
C6
What is the cricoid cartilage?
- Prominence that is felt at the inferior of the laryngeal prominence
- At the level of C6
- At C6 the pharynx continues as the esophagus and the larynx as the trachea
- Posteriorly -> Broad Portion
- Anteriorly -> Narrow Arch
What is the origin of the sternocleidomastoid?
It has two heads:
1) The sternal head: From the upper part of the anterior surface of the manubrium sterni
2) The clavicular head: Upper surface of the medial 1/3 of the clavicle
What is the insertion of the sternocleidomastoid?
1) Mastoid process
2) The lateral 1/3 of the superiornuchal line
What is the nerve supply of the sternocleidomastoid?
- The spinal accessory nerve (motor & proprioceptive)
- C2 & C3 (cranial nerve 11)
What is the action of the sternocleidomastoid?
1) Elevates the ribs during forced inspiration when the neck is fixed
2) It tilts the head to the same side & turns the face to the opposite side
- Allows left ear to touch the shoulder & pointing chin upwards to the opposite side
- Pigeon/Chicken Movement of the head is also done by this muscle (Moving chin forward)
What are the attachments of the digastric muscle?
- 2 bellies that are joined by an intermediate tendon (anterior & posterior)
1) The anterior belly is attached to the mandible
2) The posterior belly is attached to the mastoid process
3) The intermediate tendon connects it to the hyoid bone via a fibrous sling
What are the attachments of the omohyoid bone?
- It consists of superior and inferior bellies
1) The superior belly is lateral to the sternohyoid and runs downwards and laterally, passing deep into the sternomastoid
2) The inferior belly passes in the posterior triangle to reach the superior scapular fossa
- The two bellies are joined by a flat tendon deep to the posterior surface of the sternomastoid
What are the attachments of the sternohyoid muscle?
- Extends from the hyoid to the sternum (bilateral)
What are the subdivisions of the neck?
- It is divided by the sternocleidomastoid muscle into two main triangles:
1) Anterior triangle
2) Posterior triangle
What are the boundaries of the anterior triangle?
1) Anteriorly: The median line
2) Posteriorly: The sternocleidomastoid
3) Base: Ramus of the mandible + the line from the angle to the mastoid
4) Apex: The suprasternal notch
What are the subdivisions of the anterior triangle?
1) Muscular triangle
2) Carotid Triangle
3) Digastric/submandibular triangle
4) Submental triangle
What are the boundaries of the muscular triangle?
1) Superiorly: Belly of the superior omohyoid
2) Anterior lower border of the sternomastoid
3) Mid-imaginary plane
What are the boundaries of the carotid triangle?
1) Posterior belly of the digastric
2) Upper posterior border of the sternomastoid
3) Posterior border of the superior belly of the omohyoid
- It contains the carotid sheath
What are the boundaries of the Digastric/submandibular triangle?
1) Posterior border of the anterior belly of the digastric
2) Lined below by the mandible
3) Posterior belly of the digastric
- Contains the submandibular gland
What are the boundaries of the submental triangle?
1) Anterior border of the anterior gastric
2) Base by the hyoid bone
3) Mid-imaginary line
- Contains the submental lymph nodes
What are the boundaries of the posterior triangle?
1) Anteriorly: Sternomastoid
2) Posteriorly: Trapezius
3) Apex: The meeting point between the trapezius & sternomastoid at the back of the skull
4) Base: The middle 1/3 of the clavicle between the attachments of the sternomastoid and the trapezius
What are the suprahyoid muscles?
- Don’t Sit More, Go Harder
1) Digastric muscle
2) Stylohyoid
- Above the posterior belly of the digastric muscle
- It extends between the styloid process & hyoid bone
3) Mylohyoid
-It extends between the mandible and hyoid bone
- It is attached to a midline raphe
4) Geniohyoid
- Extends between the mandible and hyoid bone
5) Hypoglossus
- Between the hyoid bone and the tongue
What are the infrahyoid muscles?
1) Sternohyoid
- Superficial to the sternothyroid and thyrohyoid
- It is between the manubrium and hyoid bone
2) Omohyoid
3) Sternothyroid
- It extends between the manubrium and the oblique line of the thyroid cartilage
4) Thyrohyoid
- From the oblique line of the thyroid cartilage to the hyoid bone
FYI: All of them are innervated by the Ansa cervicalis nerve (except the thyrohyoid innervated by C1 “Hypoglossal nerve”)
