Muscles of the Trunk and Neck Flashcards
also called axial muscles and are classified morphologically into hypaxial and epaxial groups:
MUSCLES OF THE
TRUNK AND NECK
lie dorsal to transverse process of the vertebrae; function mainly as extensors of the vertebral column
EPAXIAL
include the muscles of the abdominal and thoracic walls
HYPAXIAL
*Muscles of the Neck
arises from transverse processes of cervical vertebrae and inserts on the ventral surface of basioccipital bone of the skull
longus capitis
*Muscles of the Neck
covers the ventral surfaces of the vertebral bodies from the sixth thoracic vertebrae to the atlas; can be felt when you insert your finger into the thoracic inlet because of its location
longus colli
*Muscles of the Thoracic Wall
a muscle of inspiration which attaches to the first few ribs and the transverse processes of the cervical vertebrae; divided into several slips
scalenus
*Muscles of the Thoracic Wall
large, fan-shaped muscle with extensive origin on the neck and trunk; inserts on the serrated face of the scapula
serratus ventralis
*Muscles of the Thoracic Wall
*Serratus dorsalis
arises from thoracolumbar fascia and inserts on the
craniolateral surfaces of the ribs. It lifts ribs during inspiration.
serratus dorsalis cranialis
*Muscles of the Thoracic Wall
*Serratus dorsalis
arises from the thoracodorsal fascia and inserts on caudal borders of the last 3 ribs; draws the last 3 ribs caudally during expiration
serratus dorsalis caudalis
*Muscles of the Thoracic Wall
fibers run caudoventrally from the caudal border of one rib to the cranial border of the rib behind. They draw the ribs together during respiration.
external intercostal muscles
*Muscles of the Thoracic Wall
can be differentiated from external intercostal muscles because their fibers run cranioventrally from the cranial border of one rib to the caudal border of the rib in front of it; draw the ribs together
internal intercostal muscles
*Muscles of the Thoracic Wall
thin triangular muscles deep the transversus abdominis; crosses the space between the 1st few lumbar transverse processes and the last rib; arises from thoracolumbar fascia
retractor costae
*Muscles of the Thoracic Wall
lies on inner surface of sternum and the sternal costal
cartilages (2nd to last segment); fibers came from sternum and insert into costal cartilages; aids expiration
transversus thoracis
*Muscles of the Thoracic Wall
flat to rectangular muscle that runs caudoventral from 1st rib and inserts by a fascia at distal end of 3rd and 4th rib; moves forward during inspiration
rectus thoracis
*Muscles of the Thoracic Wall
spindle-shaped muscles; arise from transverse processes of first 12 thoracic vertebrae and run caudolaterally to insert on adjacent rib
levatores costarum
*Muscles of the Thoracic Wall
a tendinous central sheet; fibers attach along costal arch;
diaphragm
*Muscles of the Abdominal Wall
covers the ventral half of the lateral thoracic
wall and the lateral part of the abdominal wall; fibers run caudoventrally; in the ventral abdominal wall it forms a wide aponeurosis that inserts on the linea alba
external abdominal oblique
is the midventral aponeurosis of the abdominal muscles from xiphoid cartilage to prepubic tendon
linea alba
a slit between the abdominal muscles from the deep to the superficial inguinal ring
Inguinal canal
- vaginal tunic – a thin membrane beneath the abdominal muscles which is an extension of the peritoneum
- testes and spermatic cord – enclosed by the vaginal tunic
- external pudendal artery and vein
- genitofemoral nerve
Structures that enter the inguinal canal
In the male animal:
- vaginal process
- round ligament of the uterus – enveloped by the vaginal process
- external pudendal artery and vein
- genitofemoral nerve
Structures that enter the inguinal canal In the female animal:
*Muscles of the Abdominal Wall
fibers run cranioventrally; fibers from caudal border of this muscle form the cremaster muscle which accompanies the vaginal tunic
internal abdominal oblique
*Muscles of the Abdominal Wall
fibers run transversely; lies medial to the internal
abdominal oblique and rectus abdominis
transversus abdominis
*Muscles of the Abdominal Wall
extends from the pubis to the sternum; has distinct
transverse tendinuos intersections; right and left muscles are separated by linea alba
rectus abdominis
Actions of Abdominal Muscles (2)
a. contract to increase abdominal pressure in defecation, urination, expiration and parturition
b. flex vertebral column
Nerve Supply: ventral branches of spinal nerves
Epaxial Muscles 3 divisions
- iliocostalis system
- transversospinalis system
- longissimus system
*ILIOCOSTALIS SYSTEM
arises from wing of ilium and inserts on the transverse
processes of the lumbar vertebrae and the last 4 or 5 ribs; fused with longissimus lumborum at the lumbar region.
iliocostalis lumborum
*ILIOCOSTALIS SYSTEM
arises from the 12th rib to the transverse processes of C7
iliocostalis thoracis
- most medial and deep epaxial muscle mass
- extends from the sacrum to the head; includes spinalis, semispinalis, multifudus, rotators, interspinalis, intertransversarii
TRANSVERSOSPINALIS SYSTEM
*TRANSVERSOSPINALIS SYSTEM
dorsolateral surface of the neck under rhomboideus capitis and serratus dorsalis cranialis; extends from spines of first three thoracic vertebrae and inserts on nuchal crest and mastoid part of the temporal bone
splenius
*TRANSVERSOSPINALIS SYSTEM
cervical portion of the transversospinalis group; lies deep to the splenius and extends from the thoracic vertebrae; consists of:
◦ biventer cervicis – from thoracic vertebra and inserts on the caudal surface of the skull; has tendinous intersection
◦ complexus – ventral to the biventer and arises from cervical vertebra and inserts on the nuchal crest
semispinalis capitis
