PAS 407 Axilla (armpit) UPDATED ACTUAL Questions and CORRECT Answers
bony boundary formed by clavicle, 1st rib, and scapula
Superior (apex) boundary of axilla
passage for structures passing between neck and axilla
continuous with upper arm and is in part reinforced by the
Base boundary of axilla
axillary nerve
wall formed by the pectoral (minor and major) region of
the shoulder
border ends inferiorly at the anterior axillary fold
Anterior boundary of axilla - formed by the lateral border of pectoralis major muscle
wall formed by the body of the scapula, associated scapu-
lohumeral muscles (subscapularis muscles), and latis-
simus dorsi muscle
border ends inferiorly with posterior axillary fold
- composed of both latissimus dorsi and teres major mus-
Posterior boundary of axilla
cles
formed by lateral border of rib cage and overlying mus-
Medial boundary of axilla
culature (serratus anterior)
, Small boundary on proximal humerus between the inser-
tions of pectoralis major, latissimus dorsi
image: lateral boundary would be the dent on the
humerus head (btw latissimus dorsi and pec muscle)
Lateral boundary of axilla
most superficial portion of medial wall of axilla
broad origin off of ribs through 1 to 8
- named for serrated appearance of muscle origin
origin of serratus anterior muscle
wraps posteriorly (around lateral thoracic wall) to insert on
the medial border of scapula
[note when lateral border of scapula is reflected poste-
insertion of serratus anterior muscle
riorly, medial border of scapula define the bottom of a
V formed by serratus anterior anteriorly and subscapu-
laris posteriorly (wedge-shaped btw posterior and medial
wall)]
, contracts to protract the scapula (pull arm forward)
- important muscle in quadrupeds to elevate thorax while
walking
Notes:
slide scapula anterolaterally along wall of thoracic =
scapular protraction...this serve to max project arm ante-
riorly when reaching forward
action of serratus anterior - bc of radiating pattern of muscle fibers, selective con-
traction of superior/inferior portions of muscle can cause
upward/downward rotation of scapula respectively
another role of scapula is to work synergy with trapezius to
co-contract, pulling medial border of scapula flat against
posterior thoracic wall - important to quadrupeds
- assist in keeping scapula flat against thoracic wall, pre-
vent drooping of thoracic wall when standing or walking
long thoracic nerve
innervation of serratus anterior
- lateral thoracic artery
during axillary surgeries, trauma (object gets jammed in
axilla), resulting in paralysis of serratus anterior;
results in scapular winging** in pushup position (unable
when can long thoracic nerve be injured?
to hold scapula flat against body wall)
image: scapular winging
bony boundary formed by clavicle, 1st rib, and scapula
Superior (apex) boundary of axilla
passage for structures passing between neck and axilla
continuous with upper arm and is in part reinforced by the
Base boundary of axilla
axillary nerve
wall formed by the pectoral (minor and major) region of
the shoulder
border ends inferiorly at the anterior axillary fold
Anterior boundary of axilla - formed by the lateral border of pectoralis major muscle
wall formed by the body of the scapula, associated scapu-
lohumeral muscles (subscapularis muscles), and latis-
simus dorsi muscle
border ends inferiorly with posterior axillary fold
- composed of both latissimus dorsi and teres major mus-
Posterior boundary of axilla
cles
formed by lateral border of rib cage and overlying mus-
Medial boundary of axilla
culature (serratus anterior)
, Small boundary on proximal humerus between the inser-
tions of pectoralis major, latissimus dorsi
image: lateral boundary would be the dent on the
humerus head (btw latissimus dorsi and pec muscle)
Lateral boundary of axilla
most superficial portion of medial wall of axilla
broad origin off of ribs through 1 to 8
- named for serrated appearance of muscle origin
origin of serratus anterior muscle
wraps posteriorly (around lateral thoracic wall) to insert on
the medial border of scapula
[note when lateral border of scapula is reflected poste-
insertion of serratus anterior muscle
riorly, medial border of scapula define the bottom of a
V formed by serratus anterior anteriorly and subscapu-
laris posteriorly (wedge-shaped btw posterior and medial
wall)]
, contracts to protract the scapula (pull arm forward)
- important muscle in quadrupeds to elevate thorax while
walking
Notes:
slide scapula anterolaterally along wall of thoracic =
scapular protraction...this serve to max project arm ante-
riorly when reaching forward
action of serratus anterior - bc of radiating pattern of muscle fibers, selective con-
traction of superior/inferior portions of muscle can cause
upward/downward rotation of scapula respectively
another role of scapula is to work synergy with trapezius to
co-contract, pulling medial border of scapula flat against
posterior thoracic wall - important to quadrupeds
- assist in keeping scapula flat against thoracic wall, pre-
vent drooping of thoracic wall when standing or walking
long thoracic nerve
innervation of serratus anterior
- lateral thoracic artery
during axillary surgeries, trauma (object gets jammed in
axilla), resulting in paralysis of serratus anterior;
results in scapular winging** in pushup position (unable
when can long thoracic nerve be injured?
to hold scapula flat against body wall)
image: scapular winging
