Download MBBS (Bachelor of Medicine, Bachelor of Surgery) Human Anatomy ppt lectures Topic 6 Pectoral Region Notes. - anatomy ppt free download human anatomy ppt lectures, medicine notes ppt, anatomy handwritten notes pdf, mbbs 1st year anatomy notes pdf download, best anatomy notes pdf, human anatomy notes pdf, anatomy easy notes pdf, anatomy notes online, anatomy short notes, Anatomy ppt, Powerpoint Presentations and lecture notes.
OBJECTIVES
? By the end of the lecture the students should be able
to :
? Identify and describe the muscles of the pectoral region.
? Pectoralis major.
? Pectoralis minor.
? Subclavius.
? Serratus anterior.
? Action of these muscles
? Clavipectoral Fascia
? Blood & Nerve Supply
? Clinical Relevance
Pectoral region
1. Bony landmark :
Sternum:
Jugular notch (body of T2)
Sternal angle of Louise (T4-5)
Xiphosternal joint (T9)
Ribs & costal cartilage
Scapular: acromian,
coracoid process
Clavicle:
Humerus:
?supraclavicular fossa
head
?infraclavicular fossa
.2Superficial structure
- skin & derivative of skin (breast)
Breast : nipple, areolar, mammary
gland (F)
1. Surface Anatomy (position) :
Nipple ? 4-5" from the midline,
intercostal space 4
Breast ? between rib 2-7
2. Components :
- subcutaneous fat, mammary gland
- Lactiferous duct
- Cooper's ligament (suspensory
ligament)
- Retinaculum cutis fascia
The majority of the breast is in the superficial fascia, except the tail part
(Tail of Spence) extends upward laterally into deep fascia at the lower border of
pectoralis major.
2/3 of the gland lies on pectoralis major
1/3 of the gland lies on serratus anterior
Deltopectoral Triangle
-deep fascia separating deltoid and pectoralis muscles
- Platysma = superficial muscle, thin plate, extends from the mandible to the
clavicle
3. Muscles of pectoral
region
a. Pectoralis Major
b. Pectoralis Minor
c. Serratus Anterior
d. Subclavious
Pectoralis major
Origin
Anterior sternal half of the
clavicle;
Manubrium and Sternum upto
sixth costal cartilages
Cartilages of al the true ribs,
Aponeurosis of the abdominal
external oblique
Insertion
By a bilaminar tendon into the
lateral lip of the bicipital
groove of the humerus
Innervation
Medial and lateral pectoral
nerves
Flexion of the
Actions
humerus,
Adduction of the
humerus and
Medial rotation of
the humerus.
Clavicular part : flexion,
adduction, and medial
rotation of the
humerus.
Sternocostal part
extension of the flexed
arm as in climbing.
It aids in deep
inspiration.
Origin
It
Pectoralis minor
arises from the upper margins and outer
surfaces of the third, fourth, and fifth ribs,
Inserted into the medial border and upper
surface of the coracoid process of the scapula.
Innervation
Medial and lateral pectoral nerves
Actions
Protracts the scapula with serratus anterior
Depresses the shoulder with the rhomboids
and levator scapulae
Important
The pectoralis minor muscle is covered by
the clavipectoral fascia.
The medial pectoral nerve pierces the
pectoralis minor .
Axil ary artery is divided into three parts by
pectoralis minor.
Clavipectoral fascia
Encloses subclavius and Pectoralis
Minor.
It is pierced by :
Lateral pectoral nerve.
Thoraco- acromial artery
Cephalic vein.
Lymph nodes from pectoral
region to apical group of axil ary
lymph nodes
PectoralGirdle : clavicle,
scapular, ribs
Clavipectoral fascia /
Costocoracoid
membrane
- deep fascia separating the
pectoralis and the subclavious
Serratus anterior Origin
Arises from ribs 1 to 8, to be inserted into
the medial border of the scapula.
Insertion
? Medial border of the scapula between
the superior and inferior angles.
? 1st and 2nd digitations to upper angle of
scapula.(C5)
? 3rd and 4th digitations to medial border on
costal surface upto the inferior angle.
? Lower 4 digitations to inferior angle of
scapula.
Action
Protraction of the scapula along with
pectoralis minor.
? The fibres inserted on inferior angle
rotate scapula laterally and upwards in
overhead abduction with trapezius.
Assists in respiration.
Innervation
long thoracic nerve(Nerve of Bell)
-Blood supply to the pectoral region
1. Axillary artery
2. Perforating branches of the internal thoracic a.
1. Axillary artery :
divided into 3 parts
First part :
Supreme thoracic a.
Second part :
1.Thoraco-acromial trunk
Acromial branch
Pectoral branch
Clavicular branch
Deltoid branch
2. Lateral thoracic a.
Third part :
give branches to supply head of humerus and
scapular regions
Venous drainage at the pectoral region
.1Deep veins - axillary v. <= from the muscles
.2Superficial veins
- cephalic v. (from upper limb) at the
deltopectoral triangle, it pierces the
clavipectoral fascia (or infraclavicular fossa)
into the axillary v.
-from mammary gland, it drains into deep veins
=> internal thoracic v. and lateral thoracic v.
Nerve Supply of the pectoral region
.1- medial & lateral pectoral nerve (terminal
branches from the cords of the Brachial plexus (C5-
8 & T1)
- nerve to subclavius (a branch from upper trunk of
the Brachial plexus)
- long thoracic nerve (nerve roots from C5-6-7 of
the Brachial plexus)
Brachial plexus (C5-8 & T1)
.2Spinal n. / Sensory (cutaneous) n
- Supraclavicular nerve (C3-4, medial, intermediate & lateral branches)
- Intercostal nerve T3-7 (anterior & lateral cutaneous branches)
*Dermatome at the pectoral region: C3-4, T3-7
Applied aspect
? Serratus anterior is called the
Boxer's muscle since it is
responsible for pushing and
punching movements.
? Paralysis of this muscle results
in a "winged scapula" ,results
in protrusion of the scapula on
the af ected side when the
patient is asked to push
against the wall with both
arms extended.
? Winged scapula occurs in
lateral thoracic nerve
paralysis
Paralysis of Serratus anterior
muscle.
Clinical Relevance
.1Chest wall ? heart /lung sound
.2Clavipectoral fascia
- protection of the vessels and nerves underneath
-limit spreading of the abscess from upper limb to the
neck
.3Fracture of clavicle
-common site is at 1/3 from the lateral
-Poland Anomaly
-Cardiac Catheterisation- Basilic vein
1. Which one of the fol owing muscles performs adduction of the arm ?
a. Pectoralis minor.
b. Pectoralis major.
c. Subclavius.
d. Serratus anterior.
2. Serratus anterior is innervated by :
a. Thoracodorsal nerve.
b. Long thoracic nerve.
c. Axil ary nerve.
d. Radial nerve.
3. Which one of the fol owing muscles contributes in rotation of the scapula above the head?
a. Pectoralis major.
b. Pectoralis minor.
c. Serratus anterior.
d. Teres major.
4. Which one of the fol owing do not pierces clavipectoral fascia?
a. Lateral Pectoral Nerve.
b. Lymph Nodes.
c. Cephalic Vein.
d. Lateral thoracic artery.
5. Nerve to subclavius is a branch from which part of brachial plexus?
a. Roots.
b. Divisions.
c. Cords.
D. Trunks.
This post was last modified on 05 April 2022