Figure 2. Muscle of the ventral surface of the upper arm
from Gray, 1858.
Muscles
of the Upper Limb
The
upper limb (or arm) consists or three distinct regions:
the shoulder, the upper arm (brachium) and the
forearm (antibrachium).
1.
Shoulder
There
are six primary muscles of the shoulder:
a.
deltoid
- What would this muscle look like?
- originates on the scapula and clavicle; inserts on the
humerus
- elevates the arm (abducts) at the shoulder
b.
supraspinatus (supra, L: "above",
"over", or "beyond"; spina,
L: "spine")
c.
infraspinatus (infra, L: "below";
spina, L: "spine")
d.
subscapularis (sub, L: "below";
scapul, L: "shoulder blade")
e.
teres minor (teres, L: "round";
minor, L: "small")
f.
teres major (teres, L: "round";
major, L: "larger")
The
supraspinatus, infraspinatus, subscapularis,
and teres minor are the muscles of the rotator
cuff. These muscles are involved in throwing and help
to stabilize the humerus (upper arm) in the socket of
the shoulder. It is the supraspinatus that is
most often damaged in baseball players.
