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Health Sciences 2300A/B Lecture Notes - Medial Pectoral Nerve, Lateral Pectoral Nerve, External Intercostal Muscles

Health Sciences
Course Code
HS 2300A/B
Jeremy Roth

of 7
The Muscular System (Muscles of the Trunk)11/6/2012 11:34:00 AM
Deep Back Muscles
Origin of illiocostalis is iliac crest
Insertion is the ribs
Runs by the spinous process.
The true back muscles, keep you upright. Extend the trunk. Maintain
Missing a whole chunk
Intercostals (between the ribs) :
Between the ribs is the External intercostal muscles. Involved in inspiration
If the external ICs are peeled away, then the internal Intercostals are
revealed. These are involed in expiration.
There is a third layer that is called the innermost intercostal layer.
Nerves that innervate are called intercostal nerves and vessels. Also
inervate the abdominal muscles. (rectus abdominus, external oblique, etc)
They run in the intervertebral foramen.
External inercostal:
Origin: inferior border of rib
Insertion: superior portion of the rib below
Any muscles with attachments to the ribs will influence in forced breathing.
Innervation comes from the phrenic nerve.
Innervation comes from the phrenic nerve.
C 3,4,5 keep the diaphragm alive.
Is at the bottom of the ribcage.
If there is a injury to spinal accord above or below c3 then there is damage
to the phrenic nerve and breathing needs to be assisted.
Is at the bottom of the ribcage.
If there is a injury to spinal accord above or below c3 then there is damage
to the phrenic nerve and breathing needs to be assisted.
Attachements: xiphoid process, ribs and costal cartilages, lumbar vertebral
There is a central tendon in the middle of the muscle.
Vena hiatus: hole that lets the inferior vena cava pass through
Esophagial hiatus: allows the esophagus to run through the diaphragm
Perineum and the Pelvic Diaphragm:
2 layers in each gener
Muscles of Pectoral Girdle and Upper Limb11/6/2012 11:34:00 AM
know muscular attachments
common nerve supply
muscular function
***Brachial Plexus*** (know for exam):
runs from C4 to T2. Different levels of the spinal chord contribute to
Purpose of plexus is Redundancies in inervation in regards to a particular
If there is damage to a level of the spinal chord, there can still be partial
inervation due to the multiple levels of spinal chord that are contributing to
Muscles of the Pectoral Girdle:
Separated into 2 groups:
1. Muscles that move the shoulder (directly move the scapula and clavicle)
a. anterior
Originates off of the first rib and inserts on the underside of clavicle
Braces the clavicle to withstand forces generated it
o Innervated by the subclavian nerve (nerve to subclavian
Pectoralis Minor:
Minor muscle of the pectoral muscles
Originates rib 3 to rib 5 (varies in individuals) and inserts in the corcoid
process of the corcoid process of the scapula
Causes abduction.
Pulls the scapula down (causes downwards roation) also abduction
Innervated by medial pectoral nerve (both medial and lateral pectoral nerve
innervate the pectoralis major).
Serratus Anterior:
Originates from rib 1 to rib 9
Insertion point is medial border of the scapula (wraps underneath)