Anatomy Slides

Question 1

Answer 1

Mylohyoid

• origin = mylohyoid line
• insert = anterior fibres interdigitate to form the raphe, poserior fibres attach to hyoid bone
• function = raises floor of the mouth during swallowing, elevates hyoid bone, depresses mandible when hyoid bone is fixed by infra hyoid muscles
• nerve supply = nerve to mylohyoid (CNV₃)

Question 2

Answer 2

Anterior belly of digastric

• origin = digastric fossa
• insertion = digastric tendon
• function = action of digastric is depression of the mandible when hyoid bone is fixed or elevation of the hyoid bone
• nerve supply of ant. belly = nerve to mylohyoid (CNV₃)

Question 3

Answer 3

Clavicular head of sternocleidomastoid

• origin = medial one third of clavicle
• insertion = mastoid process
• consists of muscular fibres
• nerve supply = accessory nerve
• function = if both muscles acts then head is moved forwards, if one muscle acts then the head is tipped towards the shoulders on the same side or rotated to the opposite side

Question 4

Answer 4

Sternal head of sternocleidomastoid

• origin = manubrium
• insertion = mastoid process
• consists of muscular fibres
• nerve supply = accessory nerve
• function = if both muscles acts then head is moved forwards, if one muscle acts then the head is tipped towards the shoulders on the same side or rotated to the opposite side

Question 5

Answer 5

Sternohyoid

• origin = manubrium/clavicle
• insertion = hyoid bone
• function = depression of hyoid bone (after swallowing)
• nerve supply = ansa cervicalis

Question 6

Answer 6

Superior belly of omohyoid

• origin = central tendon
• insertion = hyoid bone
• function = depresses hyoid bone/larynx
• nerve supply = ansa cervicalis

Question 7

Answer 7

Sternothyroid

• origin = manubrium
• insertion = thyroid cartilage
• function = depressing larynx after it has been elevated during swallowing
• nerve supply = ansa cervicalis

Question 8

Answer 8

Thyrohyoid

• origin = thyroid cartilage
• insertion = hyoid bone
• function = depresses hyoid bone / raises larynx
• nerve supply = ansa cervicalis

Question 9

Answer 9

Internal Jugular Vein

• tributary seen in this slide is facial vein
• IJV exits the skull via the jugular foramen

Question 10

Answer 10

Submandibular salivary gland

• superficial part sits in the mandibular fossa
• deep part is wrapped around free edge of mylohyoid
• the duct comes from the deep part and opens at the sublingual papilla
• parasympathetic supply = submandibular ganglion (chorda tympani)
• sympathetic supply = superior cervical ganglion

Closely related structures

• lingual nerve is close to the duct
• hypoglossal nerve deep to it
• marginal mandibular is inferior to it

Question 11

Answer 11

Posterior belly of digastric

• origin = mastoid notch (behind mastoid process)
• insertion = central tendon
• function = depression of mandible when hyoid bone is fixed or elevation of hyoid bone/larynx
• nerve supply = digastric branch of the FACIAL NERVE (ant. belly is trigeminal)

Question 12

Answer 12

Laryngeal Prominence

• made up of the thyroid cartilage
• angle of fusion is 90 degrees in males and 120 in females
• grows forward during puberty - greater the length, deeper the pitch

Question 13

Answer 13

Cricothyroid membrane

• cut during emergency cricothyrotomy if the airway is blocked above this level