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Mostración Cadavérica 2022 - Hombro y Brazo
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Mostración Cadavérica 2022 - Hombro y Brazo

New Section

The speaker introduces themselves as a teaching assistant in anatomy at the Faculty of Medicine and part of the cadaveric demonstration team for 2022. They outline the order of topics to be covered, starting with bones, moving on to the shoulder joint complex, shoulder muscles, and arm muscles.

Bones of the Shoulder Region

  • The bones in the shoulder region include the scapula, clavicle, and humerus.
  • Clarification is provided on the concept of the pectoral girdle or scapular girdle that connects the upper limb appendicular skeleton to the axial skeleton.
  • Description of the clavicle as a long bone with lateral and medial extremities, superior and inferior surfaces, anterior and posterior borders.

Clavicle Anatomy

  • Differentiation between lateral (flat) and medial (bulky) extremities of the clavicle.
  • Distinguishing features of superior (smooth) and inferior (with bony prominences like subclavian groove) surfaces.

Scapula Description

  • Explanation on how to determine if it's a right clavicle based on its convex/concave anterior/posterior edges.
  • Articulation points: acromion with acromial end; sternal end for articulation with sternum.

Shoulder Muscles Overview

The discussion transitions into detailing muscle attachments and landmarks on both clavicles and scapulas.

Clavicle Muscle Insertions

  • Identification of muscle insertion sites like pectoralis major, sternocleidomastoid, deltoid, trapezius on superior surface.

Scapula Muscle Attachments

  • Description of scapula as a flat bone emphasizing length over thickness for muscle attachment efficiency.

Scapula Landmarks

Anatomy of the Scapula and Humerus

The transcript delves into the anatomical features of the scapula and humerus, highlighting key structures and their functions.

Anatomical Features of the Scapula

  • The scapula has various insertions such as the deltoid muscle on its inferior aspect and roughness near the inferior angle for the latissimus dorsi muscle.
  • Notable structures include the acromion process, infraglenoid tubercle for triceps brachii, and coracoid process for biceps brachii.
  • The supraglenoid tubercle houses the long head of biceps brachii. Additionally, there is an apophysis for pectoralis minor insertion.

Ligaments and Muscles Attachment Points

  • Ligaments like transverse superior/inferior close off areas on the scapula. Muscles like levator scapulae and rhomboids attach to specific regions.
  • The ligamentum coracoacromiale forms a vault where supraspinatus muscle slides. Ligaments aid in vascular passage around scapular regions.

Proximal Humerus Anatomy

  • The humerus articulates with the scapula at glenohumeral joint and with ulna/radius at elbow joint. Its proximal end includes identifiable landmarks like greater/lesser tubercles.
  • Identifying right/left humerus involves analyzing transverse/sagittal/coronal planes to distinguish superior/inferior, medial/lateral, anterior/posterior aspects.

Detailed Epiphysis Proximal Description

  • The head of humerus articulates with glenoid cavity via glenohumeral joint. Tubercles provide attachment sites for muscles like subscapularis, supraspinatus, infraspinatus.
  • Distinctive features include a spherical head oriented medially/posteriorly/superiorly separated by an anatomical neck from proximal epiphysis body. Greater tubercle serves as an attachment site for rotator cuff muscles.

Anatomy of the Shoulder Joint

In this section, the anatomy of the shoulder joint is discussed, focusing on specific structures and their relationships within the joint.

Structures in the Shoulder Joint

  • The groove between the two tubercles is known as the intertubercular sulcus or bicipital groove. It houses the tendon of the long head of the biceps brachii and an arterial branch from the anterior circumflex humeral artery.
  • Muscular insertions around the intertubercular sulcus include pectoralis major on the lateral lip, latissimus dorsi at its base, and teres major on the medial lip.
  • The diaphysis of the humerus has three faces: anterolateral, anteromedial, and posterior, separated by prominent borders. The anterolateral face features a roughness called deltoid tuberosity for deltoid muscle insertion.
  • The posterior face includes structures like radial nerve groove where radial nerve passes and triceps brachii muscle insertions.

Articular Complex of the Shoulder

This part delves into defining an articular complex before detailing five key articulations forming the shoulder joint complex.

Articular Complex Definition

  • An articular complex comprises joints that work together to facilitate specific movements.
  • The shoulder's articular complex consists of five main joints: glenohumeral joint, subacromial joint, scapulothoracic joint, acromioclavicular joint, and sternoclavicular joint.

Classification of Joints

  • Glenohumeral and subacromial joints are classified under lateral group with extensive movement capabilities.
  • Scapulothoracic, acromioclavicular, and sternoclavicular joints belong to a medial group with crucial roles in shoulder movements.

Joint Characteristics

  • Subacromial joint is a simple synovial joint involving only humerus and scapula with liquid-filled synovial tissue but lacks compartmentalization.
  • Scapulothoracic joint is functionally significant for muscle sliding without being a true anatomical joint; it aids in smooth movement between muscles like deltoid and rotator cuff muscles.

Detailed Articulation Joint Analysis

In this section, the speaker delves into the intricate details of various articulation joints in the human body, focusing on structures and movements within these joints.

Understanding Muscle Sliding in Articulation Joints

  • The sliding plane between muscles reveals a bursa present in the scapula joint.
  • Emphasizes two key spaces for observation: erratic space and conservative space.

Muscle Interaction in Specific Articulation Joints

  • Describes sliding occurring between subscapularis muscle and serratus anterior muscle.
  • Details insertion of subscapularis muscle into the subscapular fossa on the anterior side of the scapula.

Analysis of Acromioclavicular Joint

  • Defines acromioclavicular joint as a simple joint involving only the acromion of scapula and acromial end of clavicle.
  • Classifies it as a synovial joint due to its flat nature with synovial fluid, facilitating limited sliding movements.

Examination of Sternoclavicular Joint

  • Identifies sternoclavicular joint as a compound joint involving first costal cartilage, sternum, and clavicle.
  • Categorizes it as a synovial type with reciprocal disc structure for complete compartmentalization.

Anatomy of the Shoulder Region

In this section, the detailed anatomy of the shoulder region is discussed, focusing on specific muscles and their attachments.

Muscles in the Shoulder Region

  • The subscapular muscle extends across the anterior aspect of the glenohumeral joint towards the lesser tubercle of the humerus.
  • The supraspinatus muscle is located in the supraspinous fossa of the scapula, passing superiorly to insert into the superior facet of the greater tubercle of the humerus.
  • The infraspinatus muscle travels through the posterior aspect of the glenohumeral joint to attach to the middle facet of the greater tubercle of humerus.
  • The teres minor muscle extends from the posterior aspect of glenohumeral joint towards inferior facet of greater tubercle of humerus.

Muscle Insertions and Observations

  • Detailed observations are made on various muscular insertions in a prepared specimen, highlighting structures like pectoralis major, long head biceps brachii, latissimus dorsi, and teres major.
  • Fibers and tendons reaching apophysis coracoid are associated with biceps brachii and coracobrachialis muscles.

Articulations and Ligaments

  • The acromioclavicular joint is described as a synovial plane joint connecting acromion process with clavicle's lateral end via ligaments like superior and inferior acromioclavicular ligaments.
  • Ligaments such as coracoclavicular ligaments and trapezoid ligament play crucial roles in maintaining clavicle-scapula connection.

Clavicular Articulation Details

  • An overview is provided on external costoclavicular articulation involving ligaments like anterior/posterior/superior clavicular ligaments along with interclavicular and costoclavicular ligaments.

Anatomy of the Chest Muscles

In this section, the anatomy of the chest muscles is discussed, focusing on the pectoral major and minor muscles, their insertions, innervation, and functions.

Pectoral Major Muscle

  • The pectoral major muscle is located in the anterior plane of the chest.
  • It inserts its clavicular fascicles into the medial third of the anterior border of the clavicle.
  • Innervated by pectoral lateral and medial nerves from the brachial plexus.
  • Responsible for flexion, adduction, and medial rotation of the arm.

Pectoral Minor Muscle

  • Positioned beneath the pectoral major muscle.
  • Inserts into the third to fifth ribs.
  • Functions as an inspiratory muscle when fixed at coracoid process or as a depressor when fixed at ribs.

Subclavius Muscle

  • Inserts at inferior aspect of clavicle and first rib.
  • Innervated by subclavian nerve from brachial plexus.

New Section

In this section, the anatomy of the shoulder muscles is discussed, focusing on the subscapularis muscle and its functions.

Subscapularis Muscle Anatomy

  • The subscapularis muscle inserts into the subscapular fossa on the anterior surface of the scapula. Its fibers pass laterally through the anterior aspect of the glenohumeral joint and insert into the lesser tubercle of the humerus.
  • It is innervated by lateral branches of the brachial plexus.
  • The subscapular artery supplies blood to this muscle.

New Section

This part delves into a posterior view of the shoulder region, highlighting muscles like supraspinatus, infraspinatus, teres minor, and latissimus dorsi.

Posterior Shoulder Muscles Description

  • The supraspinatus muscle inserts into the supraspinous fossa on the posterior surface of the scapula. It abducts the arm and is innervated by the suprascapular nerve.
  • Infraspinatus muscle inserts into infraspinous fossa on scapula's posterior surface. It laterally rotates the shoulder and is innervated by suprascapular nerve.
  • Teres minor muscle aids in lateral rotation of shoulder; it inserts at greater tubercle of humerus.
  • Latissimus dorsi muscle has broad attachments including spine's lower vertebrae & iliac crest; it adducts & medially rotates arm.

New Section

Transitioning to arm muscles from shoulder region discussion, focusing on triceps brachii as a posterior group and biceps brachii as an anterior group.

Arm Muscles Overview

  • Triceps brachii forms a posterior group with three heads: long head (innervated by radial nerve), lateral head (radial nerve), medial head (radial nerve).
  • Biceps brachii comprises two heads: short head attaches to coracoid process via common tendon with coracobrachialis; long head goes intra-articularly to glenohumeral joint before inserting at supraglenoid tubercle.

Anatomy of the Arm Muscles

In this section, the anatomy of the arm muscles is discussed, focusing on the biceps brachii muscle and its functions.

Biceps Brachii Muscle

  • The biceps brachii muscle traverses through the coracobrachialis muscle and is irrigated by branches of the brachial artery.
  • It functions as a flexor of the forearm, flexing it over the arm. When the forearm is in pronation, it becomes an opinator.
  • Receives arteries directly from branches of the brachial artery and functions to flex the arm at the shoulder joint.

Muscles of the Arm: Brachialis Muscle

This part delves into describing the brachialis muscle, its location, insertion points, innervation, and function.

Brachialis Muscle

  • Located beneath the biceps brachii muscle and inserts proximally on the anteromedial surface of the humerus.
  • Innervated by both musculocutaneous nerve and a branch of radial nerve for double innervation. Functions to flex the forearm overarm primarily.

Triceps Brachii Muscle Anatomy

The triceps brachii muscle anatomy is explored in detail regarding its heads, insertions, innervation, and function.

Triceps Brachii Muscle

  • Inserted proximally via three heads: long head (infraglenoid tubercle), lateral head (superior and lateral to radial nerve groove), medial head (inferior and medial to radial nerve groove). Distally inserts into olecranon process of ulna.
  • Innervated by musculocutaneous nerve and receives blood supply from deep brachial artery. Functions as an extensor of forearm primarily.

Axilla Anatomy

This segment focuses on describing axilla anatomy including boundaries, contents like nerves, vessels, lymph nodes.

Axilla Anatomy

  • Axilla shaped like a superiorly open pyramid with boundaries: anterior (clavicle), posterior (upper border scapula), lateral (coracoid ligament), medial (first rib). Base consists of skin, subcutaneous tissue & axillary fascia suspensory ligament.

Contents within Axilla

Details about structures within axilla including muscles forming anterior/posterior walls & neurovascular structures are discussed.

Contents within Axilla

  • Anterior wall formed by pectoralis major/minor muscles & subclavius; posterior wall by subscapularis/teres major/latissimus dorsi; medial wall by serratus anterior digitations.

Arterial Content and Relationships

In this section, the speaker discusses the arterial content related to the axillary artery, its origin from the subclavian artery, and its continuation as the brachial artery. The relationships of the axillary artery with surrounding structures such as veins, nerves of the brachial plexus, and muscles are also highlighted.

Arterial Content Description

  • The axillary artery originates from the subclavian artery at the lower border of the clavicle and continues as the brachial artery after passing below the pectoralis major muscle.
  • As it descends through the axilla, it interacts with structures like the axillary vein anteromedially and various nerves of the brachial plexus.
  • Specific nerves like median nerve lie anteriorly to it while musculocutaneous nerve is lateral to it.
  • The axillary artery's relationships include crossing under the pectoralis minor muscle which divides it into suprapectoral, retropectoral, and infrapectoral portions.
  • It gives off six collateral branches in the axilla including superior thoracic, thoracoacromial, lateral thoracic, subscapular arteries along with two circumflex humeral arteries.

Branches of Axillary Artery

This part focuses on detailing specific branches originating from the axillary artery in a sequential manner as they emerge in relation to anatomical landmarks within or around the shoulder region.

Branches Description

  • The superior thoracic artery extends from clavicle to upper edge of pectoralis minor.
  • Thoracoacromial artery bifurcates into pectoral branch for chest muscles and deltoid branch for shoulder joint regions.
  • Lateral thoracic artery runs along ribs towards serratus anterior muscle.
  • Subscapular artery divides into thoracodorsal supplying latissimus dorsi muscle and circumflex scapular heading posteriorly towards scapula.
  • Circumflex humeral arteries consist of anterior and posterior branches contributing to shoulder regions' vascular supply.

Axillary Artery Termination

This segment delves into how the axillary artery concludes its course by giving rise to terminal branches that navigate distinct paths around critical anatomical structures within arm regions.

Termination Details

  • Axillary artery culminates by branching into circumflex posterior humeral & anterior humeral arteries which encircle surgical neck of humerus before diving deep into deltoid muscle.
  • Circumflex humeral anterior travels laterally beneath biceps brachii tendon towards glenohumeral joint providing vital blood supply routes.

Understanding the Anatomy of the Brachial Plexus

In this section, the speaker delves into the anatomy of the brachial plexus, detailing the different branches and their relationships within the body.

Branches and Formation of Fascicles

  • The brachial plexus consists of anterior and posterior branches. The posterior branches form the more posterior aspects.
  • The lateral fascicle is lateral to the axillary artery, while the posterior fascicle is posterior to it. The medial fascicle lies medially to the artery.

Pathways and Terminations

  • The median nerve descends through muscles in the arm before branching into lateral and medial roots that unite anteriorly to form a nerve near the axillary artery.
  • Nerves from different fascicles converge in regions like the lateral forearm, where lateral and medial roots merge before innervating specific areas.

Nerve Distribution in Arm Regions

This part focuses on how nerves from various fascicles distribute across different regions of the arm.

Nerve Pathways in Arm Regions

  • Nerves from lateral and medial roots combine in front of arteries like axillary, forming nerve trunks that descend through specific arm regions.
  • The median nerve becomes a significant nervous axis in areas like axilla, descending through muscles to innervate various forearm compartments.

Detailed Innervation Patterns

Exploring detailed innervation patterns within specific muscle groups along with nerve pathways.

Muscle Innervation Details

  • Significant collateral nerves branch off to innervate forearm muscles except for certain exceptions like flexor cubital del carpo.
  • Specific nerves descend through distinct anatomical spaces within arms, reaching deep muscle layers for precise innervation purposes.

Role of Radial Nerve & Collateral Nerves

Discussing how radial nerves play a crucial role alongside collateral nerves in arm functionality.

Radial Nerve Functionality

  • The radial nerve descends posteriorly through defined anatomical landmarks before branching into superficial and deep terminal nerves for muscle innervation.

Elaborate Nerve Pathways in the Upper Limb

In this section, detailed descriptions of nerve pathways in the upper limb are provided, focusing on specific muscles and their innervation.

Elaboration of Nerve Pathways

  • The injured person's lips are a superior class that will enervate the muscle of their lips. This area extends to the scapular region, involving nerves directed posteriorly through various structures.
  • Nerves from the scapula extend to the supraspinous fossa to innervate the supraspinatus muscle before reaching the infraspinous fossa for innervating the infraspinatus muscle.
  • Detailed description of nerve pathways continuing from the scapula towards muscles such as serratus anterior and other branches of the brachial plexus.

Plexus Braquial Components

  • The content of nerves within this region is primarily composed of brachial plexus fascicles, terminal branches, and collateral branches. Trunks of the brachial plexus are located above the clavicle between specific muscles.
  • Identification and discussion of different fascicles within the brachial plexus including lateral, posterior, and medial fascicles along with their respective roles in innervation.

Specific Nerve Functions

  • Exploration of nerves such as musculocutaneous nerve originating from lateral fascicle and its pathway through muscles like coracobrachialis before exiting into arm region.
  • Description of median nerve origins from lateral fascicle leading to its path alongside axillary artery forming a vascular-nervous axis in axilla before entering arm region.

Anatomy of the Brachial Plexus: Terminal Branches

In this section, the speaker discusses the terminal branches of the brachial plexus, focusing on the axillary nerve and radial nerve.

Axillary Nerve and Radial Nerve

  • The axillary nerve, also known as the circumflex nerve, originates from the posterior fascicle. It travels posteriorly and laterally through the axillary space.
  • It passes through the lateral axillary space or quadrangular space along with the posterior humeral circumflex artery.
  • The radial nerve always lies posterior to the axillary artery, descending behind the neurovascular axis of the armpit before entering the arm region.
  • Upon reaching the arm region, it is accompanied by the deep brachial artery and passes through the inferior axillary space.

Course of Radial Nerve

  • As it reaches the distal arm region, it is joined by the deep brachial artery and traverses a groove known as "radial nerve groove" on the posterior aspect of humerus.
  • The radial nerve then moves obliquely downward and laterally in an anterior muscular compartment before dividing into its superficial and deep terminal branches.

Collateral Branches

  • Pectoral Lateral Nerve: Fibers reaching deep pectoralis major muscle correspond to this branch originating from lateral fascicle but are broken in this specimen.
  • Uncertain if these fibers indeed belong to pectoral lateral nerve due to damage.
  • Thoracodorsal Nerve: Descends with thoracodorsal artery to innervate latissimus dorsi muscle.
  • Originates from C5-C6 rami directly.

Topographic Spaces in Shoulder Region

This part explores various topographic spaces within shoulder anatomy, including pectoralis grooves and triangles.

Pectoralis Groove

  • The pectoral groove lies anteriorly in shoulder region between deltoid and pectoralis major muscles.
  • It houses cephalic vein (part of upper limb's superficial venous drainage) alongside thoracoacromial trunk branch.

Triangles in Shoulder Region

  • Triangle of Deltoid: Bounded by deltoid superiorly, humerus laterally; contains long head of triceps brachii dividing it into two parts – medial (quadrangular space) & lateral (triangular).
  • Medially limited by teres minor & inferiorly by teres major; houses circumflex scapular artery & veins.
  • Triangular Space: Superiorly bordered by teres minor; inferiorly by teres major nearing its insertion; laterally by long head of triceps brachii & medially by long head of triceps brachii.
  • Contains circumflex scapular artery accompanied by circumflex scapular veins.

Axillary Spaces

  • Lateral Axillary Space: Also known as quadrilateral space #3; bounded superiorly by teres minor & inferiorly almost at its insertion point; laterally by long head of triceps brachii & medially by long head of triceps brachii.

Anatomy of the Arm: Arteries and Nerves

In this section, the anatomy of the arm focusing on arteries and nerves is discussed in detail.

Posterior Shoulder and Arm Space

  • The inferior axillary space belongs to the triangle of the round if it is inferior to said triangle. It is limited medially by the long head of the triceps, laterally by the humerus, and superiorly by other structures.

Structures in Inferior Axillary Space

  • The inferior axillary space contains various structures such as the radial nerve running through its groove accompanied by the deep brachial artery.

Arteria Braquial Origin and Pathway

  • The brachial artery originates from the lower border of the pectoralis major muscle as a continuation of the axillary artery. It extends up to the elbow joint line where it divides into two terminal branches.

Course of Brachial Artery

  • The brachial artery descends along the anteromedial aspect of the arm within a conduit called brachial canal, bordered laterally by biceps brachii and posteriorly by medial head of triceps brachii.

Branches of Brachial Artery

  • The brachial artery gives off muscular branches for all arm muscles with a constant deltoid branch. Additionally, it forms deep brachial artery which descends posteriorly towards húmero's back.