deep muscles of the back 9

deep muscles of the back

 

IHOMDOID MAJOR AND RHOMDOID IINOR MUSCLES [G

II; N 170; R 212;C 407]

1. Clean the surface and borders of the ihomboid

(rhomboileus) minor muscle and the ihomboid

major muscle (Gr. rbornbos, shaped like a kite). The

plane of separation between the rhomboid muscles

may not be obvious.

2. The  attachments of the rhomboid minor

muscle are the nuchal ligament and the spinous

processes ofvertehrrae C7 and Tl. The distal attach-

ment of the rhomboid minor muscle is the medial bor-

der of the scapula near the spine.

3. The  attachments of the rhomboid major

muscle are the spinous processes of vertebrae T2 to

T5. The distal attachment of the rhomboid major

muscle is the medial border of the scapula inferior to

the spine.

4. The rhomboid muscles retract the scapula, rotate the

scapula to depress the glenoid cavity, and hold the

stapula close to the thoracic wall.

5. Reflect the rhomboid muscles. Beginning at the infe-

rior angle of the scapula, insert your fingers deep to

the rhomboid major muscle and separate it fi'om deep-

5' muscles.

6. Use scissors no detach the rhomboid major muscle

fiom its  attachments. Continue the cut supe-

riorly and detach the rhomboid minor muscle fiom its

proximal attachments. Reflect these two muscles later-

ally.

7. Examine the deep surface of the rhomboid muscles.

Use blunt disection to find the dorsal scapular

nerve and dorsal scapular vessels. Remove the dor-

sal scapular vein to clear the dissection field. The dor-

sal scapular nerve and artery course parallel to the

medial border of the scapula. The dorsal scapular

artery may branch directly from the subclavian artery,

a' it may arise from the transverse cervical artery in

which case it is also called the deqa branch of the

transverse cervical artery.

LEVATOR SCAPULAE MUSCLE [G 308: N ‘I67; R Z14; C 407]

1. Identify the levamr scapulae muscle (L. levers, to

raise).

2. Note that the proximal attachments of the levator

rapulae muscle are the transverse proceses of the

upper four cervical vertebrae. Do not disect its prox-

inal attachments.

3. The distal attachment of the levator smpulae muscle is

the superior angle of the scapula. The levator scapulae

muscle can be seen only near its distal attachment.

4. The dorsal scapular nerve and artery supply the leva-

D!‘ scapulae muscle. The levator scapulae muscle ele-

vates the scapula and rotates the scapula to depr the

glenoid cavity.

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movements that occur between the scapula and the thoracicwall. Use an illustration to observe the origin of the transverse
cervical artery and the dorsal scapular artery. Observe two trian-
gles mmiamd with the latiwimus dorsi muscle: The triangle of
auscultation and the lumbar triangle (of Petit) (Fig. 1.09).
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INTERMEDIATE MUSCLES OE Tl-IE
BACK [6 soa; N 167; R 219; c 408]
Dissection Instructions
The intermediate muscles of the Incl: are the serratus
posterior superior muscle and the sa-ratus posterior
inferior muscle. These are very thin muscles, which may
be accidentally reflected with the rhomboid muscles or the
latisdmus dorsi muscle. If you do not see the serratus pos-
terior muscles, look for them on the deep surface of the
rhomboid muscles or the latisimus dorsi muscle.
1. The proximal attachments of the sa-ratus posterior
superior muscle are the nuchal ligament and the
spinous processes of vertebrae C7 to T3. Its distal
attachments are the superior borders of ribs 2 to 4, lat-
a‘al to their angles.
2. The proximal attachments of the sa-ratus posterior
inferior muscle are the spinous processes of vertebrae
T11 to L2. Its distal attachments are the inferior bor-
ders ofribs 8 to 12, lateral to their angles.
3. The serratus posterior muscles are respiratory mus-
des, and they are innervated by interoostal nerves.
4. Detach both serratus posterior muscles from the spin-
ous processes. Reflect the muscles laterally, leaving
them attached to the ribs.
DEEP MUSCLES OE Tl-IE BACK
Before you dissect. . .
The (hep muscles of the back act on d'1e vertebral column.
There are many deep muscles of d'1e back (Fig. 1.10) and only a
few will be dissected: splenius muscle, semispinalis capitis
muscle, and sector spinae muscle.All of d'1e deep muscles of
d'1e back are innervated by dorsal primary rami of spinal nerves.