How to add specialist name on appointment email

what to add on below code

//message body $visitorip = isset($_SERVER['HTTP_X_FORWARDED_FOR']) ? $_SERVER['HTTP_X_FORWARDED_FOR'] : $_SERVER['REMOTE_ADDR'];

    // get site name 
    $site_name      = isset($_SERVER['SERVER_NAME']) ? $_SERVER['SERVER_NAME'] : '';
    $subject        = 'Cosmo View Client Appointment request ' . ' Phone: ' . $patient_phone;

    if ( $appointment_no = $appointments_model->insertAppointment($patient_name, $patient_phone, $patient_email, $appointment_date, $patient_note, $specialist_id, $department_id, $user_id, $visitorip, $choose_patient, $date_of_birth, $patient_gender, $patient_address_street, $patient_address_city, $patient_address_state, $patient_address_zip_code, $visiting_option) )
    {

        $msg  = 'Client requested appointment through Cosmoview Website<br>';
        $msg .= '<span>Appointment ID : ' . $appointment_no .'</span><br />';
        $msg .= '<span>Astrologer Name : ' . $specialist_id .'</span><br />';
        $msg .= '<span>Client Name : ' . $patient_name .'</span><br />';
        $msg .= '<span>Client Phone : ' . $patient_phone .'</span><br />';
        $msg .= '<span>Client City : ' . $patient_address_city .'</span><br />';
        $msg .= '<span>Client Gender : ' . $patient_gender .'</span><br />';
        $msg .= '<span>Client Email : ' . $patient_email .'</span><br />';
        if($date_of_birth) {
            $msg .= '<span>Date Of Birth : ' . $date_of_birth .'</span><br />';
        }