Anatomy and Cell Biology 3319 Lecture 23: Dec 1 – Muscles of Thorax and Back Cont
1 Dec 2016
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Dec 1 muscles of thorax and back cont. All of the intrinsic muscles of the back are involved with extending vertebral column- keeping erect. Flexion = bowing, rotation or side to side bowing. When they contract together, they extend neck and skull. If splenius capitis contracts flex to same side of working muscle and also rotates skull to same side because of mastoid process. Sternocleidomastoid muscle has two heads one head originates from sternum one head originates from clavicle both travel to insert at the back of skull in mastoid process involved with movements of head. When these muscles work together you flex the neck (attached at front) Erector spinae muscle is 3 columns of muscle that run down spine. Illiocostalis (most lateral) longissimus spinalis (medial) Muscles work together to extend vertebral column. Unilateral bend to same side (lateral flexion) These muscles are filled with slow muscle fibers slow to fatigue. Postural muscles usually contracted to keep erect.
