Muscles of the Back, Trunk and Pelvic floor

Question 1

Trapezius

Answer 1

O; Descending part: Medial
third of superior nuchal
line, External occipital
protuberance, Spinous
processes of cervical
vertebrae/Nuchal
ligament
Transverse part: Broad
aponeurosis at spinous
processes of vertebrae
T1-T4 (or C7-T3)
Ascending part: Spinous
processes of vertebrae
T5-T12 (or T2-T12)

I; Descending part: Lateral
third of clavicle
Transverse part: Medial
aspect of acromion,
Superior crest of spine of
scapula
Ascending part: Medial
end of spine of scapula

N; Motor:
Accessory nerve (CN XI)
Sensory:
Anterior rami of spinal
nerves C3-C4 (via cervical
plexus)

A; Draws scapula
superomedially, Extension of head and neck,
Lateral flexion of head and
neck (ipsilateral), Rotation
of head (contralateral), Draws scapula medially, Draws scapula
inferomedially
(All parts support scapula)

Question 2

Levator

scapulae

Answer 2

O; Transverse processes of
vertebrae C1-C4

I; Medial border of scapula
(from superior angle to
root of spine of scapula)

N; Anterior rami of spinal
nerves C3-C4, Dorsal
scapular nerve (C5)

A; Scapulothoracic joint:
Draws scapula
superomedially, Rotates
glenoid cavity inferiorly;
Cervical joints: Lateral
flexion of neck (ipsilateral)

Question 3

Rhomboid

major

Answer 3

O; Spinous process of
vertebrae T2-T5

I; Medial border of scapula
(from inferior angle to
root of spine of scapula)

N; Dorsal scapular nerve
(C5)

A; Scapulothoracic joint:
Draws scapula
superomedially, Rotates
glenoid cavity inferiorly;
Supports position of scapula

Question 4

Rhomboid

minor

Answer 4

O; Nuchal ligament, Spinous
processes of vertebrae
C7-T1

I; Root (medial end) of spine
of scapula

N; Dorsal scapular nerve
(C5)

A; Scapulothoracic joint:
Draws scapula
superomedially, Rotates
glenoid cavity inferiorly;
Supports position of scapula

Question 5

Latissimus dorsi

Answer 5

O; Vertebral part: Spinous
processes of vertebrae
T7-T12, Thoracolumbar
fascia
Iliac part: Posterior third
of crest of ilium
Costal part: Ribs 9-12
Scapular part: Inferior
angle of scapula

I; Intertubercular sulcus of
humerus

N; Thoracodorsal nerve (C6-
C8)

A; Shoulder joint: Arm internal
rotation, Arm adduction,
Arm extension; Assists in
respiration

Question 6

Pectoralis

major

Answer 6

O; Clavicular head: anterior
surface of clavicle
(medial half)
Sternocostal head:
Anterior surface of
sternum, Costal
cartilages of ribs 1-6
Abdominal (Rectus) head:
Anterior layer of rectus
sheath

I;Crest of greater tubercle
of humerus (all heads)

N; Lateral and medial
pectoral nerves (C5-T1)

A; Shoulder joint: Arm
adduction, Arm internal
rotation, Arm flexion
(clavicular head), arm
extension (sternocostal
head);
Scapulothoracic joint:
Draws scapula
anteroinferiorly

Question 7

Pectoralis

minor

Answer 7

O; Anterior surface, Costal
cartilages of ribs 3-5

I; Medial border and
coracoid process of
scapula

N;Medial pectoral nerve
(C8-T1)

A; Scapulothoracic joint:
Draws scapula
anteroinferiorly, stabilizes
scapula on thoracic wall

Question 8

Serratus

anterior

Answer 8

O; Superior part: Ribs 1-2,
Intercostal fascia
Middle part: Ribs-3-6
Inferior part: Ribs
7-8/9/10 (+ external
oblique muscle)

I; Superior part: Anterior
and posterior surface of
superior angle of scapula
Middle part: Anterior
surface of entire medial
border of scapula
Inferior part:Anterior and
posterior surface of
inferior angle of scapula

N; Long thoracic nerve
(C5-C7)

A; Scapulothoracic joint:
Draws scapula
anterolaterally, Suspends
scapula on thoracic wall,
Rotates scapula (draws
inferiorly angle laterally)

Question 9

Subclavius

Answer 9

O; Costal cartilage, Sternal
end of rib 1

I; Anteroinferior surface of
middle third of clavicle

N; Nerve to subclavius
(C5-C6)

A; Nerve to subclavius
(C5-C6)

Question 10

Piriformis

Answer 10

O; Anterior surface of S2-S4
segments of sacrum,
Superior margin of
greater sciatic notch,
Sacrotuberous ligament

I; Greatertrochanter of
femur

N; Nerve to piriformis
(S1, S2)

A;Hip joint: Thigh external
rotation, Thigh abduction
(from flexed hip);
Stabilises head of femur
in acetabulum