Superficial muscles of the back

Question 1

Trapezius muscle

Answer 1

Triangular shaped
Innervation from spinal accessory nerve called cranial nerve XI
3 parts:
- Superior part (descending)
- Middle part (transverse)
- Inferior part (ascending)

Superior part
-Originates from medial third of the superior nuchal line (back of skull), the external occipital protuberance and the nuchal ligament.
-Nuchal ligament runs along spinous processes of the cervical neck.
-These muscle fibers travel inferiorly and laterally to insert at clavicle.

Transverse part
-Originates from spinous processes T1 to T4
-Travel transversely to insert on medial aspect of acromion and superior crest of spine of scapula.

Inferior part
-Originates from spinous processes T5 to T12.
-Ascend superiorly to insert on medial end of the spine of the scapula.

Question 2

Levator scapulae muscle

Answer 2

Under trapezius
-Originates from C1 to C4 transverse processes.
- Inserts on the superior part of the medial border of the scapula.
-Innervated by the anterior rami of C3 and C4 spinal nerves and dorsal scapular nerve.

Functions:
-Elevates scapula
-Rotates scapula to depress glenoid cavity.
-if only one of these muscles contracts, causes lateral flexion of neck to one side.

Question 3

Rhomboid muscle

Answer 3

Diamond shaped muscles

Rhomboid minor
-Superior to the major one and also the smaller muscle.
-Originates from spinous processes C7 and T1.
-Travels inferiorly and laterally to insert on medial border of scapula at the level of the scapular spine.
-Innervated by dorsal scapulae nerve arising from spinal nerve C5.

Rhomboid major
-Bigger and holds an inferior position.
-Originates from spinous processes T2 to T5.
-Innervated by dorsal scapulae nerve arising from spinal nerve C5.
- Travels inferiorly and laterally to insert on medial border of scapula between spine and inferior angle of scapula.

Functions:
-work together
- move scapula superomedially.
-can rotate scapula leading to depression of the glenoid cavity.

Question 4

Serratus posterior muscles.

Answer 4

serratus posterior superior
-Originates from nuchal ligament and spinous processes of C7 to T3.
-Travels laterally and a bit inferiorly to insert on ribs 2 to 5.
-Innervated by intercostal nerves 2 to 5.

Function:
-Accessory muscles of inspiration (breathing) by elevating the ribs.

Serratus posterior inferior:
-Originates spinous process T11 to C2 and thoracolumbar fascia.
-Travels superiorly and laterally to insert on ribs nine to twelve.
-Innervated by intercostal nerves 9 -11 and the subcostal nerve (travels through 12th rib).

Function:
- An accessory muscle of expiration - depresses the ribs.