Sternocleidomastoid (SCM)
Innervation
CN XI (SA nv.) + C2-3
SCM
Primary Open Chain Action
Both working together: flexion of the cervical spine
Individual muscle working alone: rotation of head to opposite side
PRIMARY NECK FLEXOR**
SCM
Secondary Open Chain Action
Ipsilateral lateral flexion (side bending)
Scalenes (ant., middle, post.)
Innervation
Cervical nerves VPR C1-8
Scalenes (ant., middle, post.)
Primary Open Chain Action
Ipsilateral flexion and rotation of the neck to opposite side
Scalenes (ant., middle, post.)
Secondary Open Chain Action
Neck flexion
Trapezius
Innervation
CN XI (SA nv.) + C3,4
Trapezius
Primary Open Chain Action
Upper fibers:
Middle fibers:
Lower fibers:
Trapezius
Secondary Open Chain Action
Unilateral:
Bilateral: head and neck extension
Levator Scapulae
Innervation
C3,4 + Dorsal Scapular (C5) to lower fibers
Levator Scapulae
Primary Open Chain Action
Elevation, adduction, and downward rotation of scapula
Serratus Anterior
Innervation
Long Thoracic n. (C5-7)
Serratus Anterior
Primary Open Chain Action
- Holds the medial border of the scapula firmly against the thorax
Serratus Anterior
Secondary Open Chain Action
- Scapular depression
Pectoralis Major
Innervation
Medial + Lateral Pectoral n. (C5-8T1)
Pectoralis Major
Primary Open Chain Action
Clavicular fibers:
-IR, flexion, horizontal adduction
Stern all fibers:
Pectoralis Major
Secondary Open Chain Action
- Depression of the shoulder girdle via the arm
Pectoralis Minor
Innervation
Medial Pectoral n. (C8T1)
Pectoralis Minor
Primary Open Chain Action
- Scapular downward rotation
Pectoralis Minor
Secondary Open Chain Action
Deltoideus
Innervation
Axillary n. (C5,6)
Deltoideus
Primary Open Chain Action
All actions of the arm (shoulder)
Anterior fibers:
-flexion (PRIMARY***)
Middle fibers:
-abduction (PRIMARY***)
Posterior fibers:
Deltoideus
Secondary Open Chain Action
Anterior + middle fibers:
-shoulder “scpation” (arm elevation in the plane of the scapula)
Anterior fibers:
Posterior fibers:
Coracobrachialis
Innervation
Musculocutaneous n. (C6-7)