 session on muscles of the upper limb. In this session, we will be learning about the axio-apendicular muscles. We will be learning specifically about the posterior axio-apendicular muscles. These are the muscles of the back which are included in the upper limb. So, there are two layers of muscles. There is a superficial layer and there is a deep layer of muscle. The superficial layer consists of two muscles. One is the trapezius and other is the latissimus dorsi. In the deep layer, there are three muscles, levator scapulae, rhomboidus minor and rhomboidus major. These five muscles will be covering in this session. Let us start with the trapezius muscle. As we all know, any muscle that we study, we have to study under these headings, the proximal attachment, its distal attachment, the nerve supply of the muscle and actions of the muscles. So, for trapezius proximal attachment, there are multiple points of proximal attachment. Here, we can see this region is the medial one-third of the superior-neutral line, medial one-third of the superior-neutral line and then here there is an elevation which is referred to as external occipital protrobrance and then there is ligamentum nuke, then there is spine of the seventh cervical vertebrae, then spine of all the thoracic vertebrae. And the fibres converge laterally and they are inserted onto the clavicle as well as on the scapula. On the clavicle, as you all know, the lateral one-thirds of the clavicle, it has got anterior border and posterior border. The posterior border gives attachment to the upper fibres of the trapezius. In general, the fibres of the trapezius are divided into upper fibres, middle fibres and lower fibres. The upper fibres gets attached onto the clavicle, the middle fibres gets attached onto the medial margin of the acromion and the lower fibres gets attached onto the spine of the scapula. So, this was about the proximal and distal attachment of the trapezius muscle. Now, supply of trapezius, trapezius is supplied by spinal part of the accessory nerve. Spinal accessory nerve is the now supply of trapezius. It also has certain proprioceptive fibres from C3 and C4 spinal segments. Then actions of the trapezius, since we know there are different fibres of the trapezius, the upper fibres of the trapezius are responsible for elevation of the scapula. The upper fibres of the trapezius acts along with levator scapulae to elevate the scapula. The middle fibres of the trapezius act along with the rhomboids muscle, the rhomboids minor and major. So, they together help in retraction of the scapula, okay? So, middle fibres of the trapezius along with rhomboids minor and major will retract the scapula. The lower fibres of the trapezius along with the upper fibres of trapezius and ceratis anterior muscle together they help in overhead abduction of the shoulder joint. Okay. So these are the various actions of the trapezius and clinical testing of the trapezius muscle is done by asking the patient to shrug the shoulder against resistance. The hand is kept here and the patient is asked to shrug the shoulder or elevate the shoulder then we can test for the trapezius muscle. Okay. So now let's cover the latissimus dorsi muscle. So here we can see this muscle is the latissimus dorsi. So latissimus dorsi muscle has also got extensive origin we will see what are the origins or we can see the proximal attachment of latissimus dorsi. The lower six thoracic vertebrae the spines of the lower six thoracic vertebrae that means T7 to T12 then the posterior lamina of the thoracolumbar fascia this fascia which we can see here white one this is the thoracolumbar fascia the posterior lamina of the thoracolumbar fascia then posterior part of the iliac crest okay and lower three or four ribs then inferior angle of the scapula. So all these are the origins of the latissimus dorsi muscle the muscle fibers go laterally to get inserted on to the floor of the bicepital groove bicepital groove as we know it has got three parts a lateral lip a medial lip and the floor lateral lip gives attachment to the pectoralis major muscle the medial lip gives attachment to the teris major muscle and floor gives attachment to the latissimus dorsi muscle okay so this was about the proximal and distal attachment of the latissimus dorsi muscle now supply of latissimus dorsi it is by the thoracodorsal nerve thoracodorsal nerve also referred to as nerve to latissimus dorsi it arises from the posterior cord of the brachial plexus root value is C6 C7 C8 okay C6 C7 and C8 is the root value for the nerve to latissimus dorsi then actions of latissimus dorsi actions we can remember by swimming action what do we do in swimming we do three actions one is adduction other is medial rotation and one more action is extension okay so adduction medial rotation and extension then repeatedly this action these three actions together we do while swimming okay so this muscle is also referred to as swimmers muscle this was all about the trapezius and the latissimus dorsi muscle now let's look at some dissected images of these muscles so this right-sided trapezius and latissimus dorsi viewed from the posterior aspect this muscle is trapezius this muscle is latissimus dorsi here also this is trapezius this is latissimus dorsi there is one clinical importance with respect to these muscles you can see a triangular region here this triangular region is referred to as triangle of auscultation okay boundaries of triangular of auscultation include this upper border of the latissimus dorsi muscle then interolateral border of this trapezius muscle and the medial border of the scapula okay this region is referred to as triangle of auscultation when a stethoscope is kept here it is lying over the six intercostal space and lung sounds can be clearly heard from this region okay so now let's move on to the next muscles so these three muscles have grouped together levator scapulae rhomboids minor and rhomboids major let's start with the levator scapulae first proximal attachment of levator scapulae is from the transverse process of the first four cervical vertebrae okay C1, C2, C3 and C4 transverse process of the first four cervical vertebrae is the proximal attachment for levator scapulae and distal attachment is along the medial border of the scapulae above the root of the spine okay this part is referred to as the root of the spine because this is the spinous process of the scapulae this region is referred to as the root of the spine okay above the root of the spine the muscle is levator scapulae it extends up to this superior angle of the scapulae okay proximal attachment is from the upper four cervical vertebrae distal attachment is on the medial border of the scapulae above the root of the spine nerve supply of levator scapulae it is supplied directly by the C3 and the C4 spinal nerves okay it also receives some branches from the C5 C5 this is the root value for dorsal scapulae now dorsal scapulae now also referred to as nerve to rhomboids okay so levator scapulae has now supplied from this directly from the C3 and C4 spinal segments as well as from the dorsal scapulae now that is C5 spinal segment action of levator scapulae it is elevation of the shoulder okay it elevates the scapula because the shoulder is elevated based on the action this muscle is named as levator scapulae because it elevates the scapulae okay so this was about the levator scapulae muscle now let's see this other two muscles rhomboids minor is seen opposite the spine of the scapulae its proximal attachment is from the C7 and T1 C7 is also called as vertebra prominence the seventh cervical vertebrae it also arises from the first thoracic vertebrae okay this T2 T3 T4 T5 this is for rhomboids major so proximal attachment of both rhomboids and major we can learn from this image C7 and T1 is for rhomboids minor T2 T3 T4 and T5 is for rhomboids major distal attachment for rhomboids minor is medial border of the scapula opposite the root of the spine and distal attachment for rhomboids major is medial border of the scapula below the root of the spine okay below the root of the spine is rhomboids major actions of rhomboids minor and major are they help in retraction of the scapula okay when they contract they will pull the medial border behind okay that is referred to as retraction of the scapula protraction of the scapula is done by serratus anterior muscle retraction of the scapula is done by rhomboids minor and major muscle now let's look at some of the dissected images of these muscles so here there is a dissected image of the posterior aspect of the back this muscle is levator scapulae this muscle is rhomboids minor and this muscle is rhomboids major okay so all these three muscles are along the medial border of the scapula easily we can remember with respect to the root of the spine above the root of the spine is levator scapulae opposite the root of the spine is rhomboids minor below the root of the spine is rhomboids major so this was all about the five muscles which we learned now let's quickly summarize what we have learned in this session so initially we started with the superficial layer of the muscles so those were trapezius and latissimus dorsi proximal attachment of trapezius was from the superior nuclear line the ligament and uk the seventh cervical vertebrae spines of all all 12 thoracic vertebrae okay all this was the proximal attachment for trapezius distal attachment was upper fibers were attached on to the clavicle middle fibers were attached on to the medial margin of the acromion and lower fibers are attached on to the spine of the scapula okay then nerve supply of trapezius was the spinal accessory nerve it also resist some proprioceptive fibers from C3 and C4 spinal segments actions of trapezius depending upon the fibers upper fibers of the trapezius along with levator scapulae way elevate the scapula middle fibers of the trapezius along with rhomboids minor and major they retract the scapula and lower fibers of the trapezius acting along with upper fibers and serratus anterior they help in overhead abduction of the shoulder joint okay then latissimus dorsi muscle this also has got extensive origin it arises from the spines of the lower six thoracic vertebrae then posterior lamina of the thoracolumbar paesia then posterior aspect of the iliac crest then inferior angle of the scapula all these are proximal attachment for latissimus dorsi distal attachment is in the floor of the bicepital groove now supplier of latissimus dorsi is C6 C7 C8 from the posterior cord of the brachial plexus the nerve is nerve to latissimus dorsi is also called as thoracodorsal nerve okay then deep layer of muscles from levator scapulae rhomboids minor and rhomboids major levator scapulae it arises from the transverse process of the upper upper for cervical vertebrae distal attachment is along the medial border of the scapula above the root of the spine now supplier of levator scapulae C3 and C4 spinal segments also C5 from dorsal scapulae now also referred to as nerve to rhomboids then rhomboids minor and major rhomboids minor arises from C7 and T1 spinous process and T2 T3 T4 and T5 is for rhomboids major distal attachment is along the medial border of the scapula opposite the root of the spine is rhomboids minor below the root of the spine is rhomboids major okay and actions of rhomboids minor and major include retraction of the scapulae okay action of levator scapulae is elevation of the scapulae okay so this was all about the session if you all have any doubts then you all can ask in the comment section below okay thank you